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Laser scanning of a recirculation zone on the Bolund escarpment
NASA Astrophysics Data System (ADS)
Mann, J.; Angelou, N.; Sj—holm, M.; Mikkelsen, T.; Hansen, K. H.; Cavar, D.; Berg, J.
Rapid variations in the height of the recirculation zone are measured with a scanning wind lidar over a small escarpment on the Bolund Peninsula. The lidar is essentially a continuous-wave laser Doppler anemometer with the capability of rapidly changing the focus distance and the beam direction. The instrument measures the line-of-sight velocity 390 times per second and scans ten wind profiles from the ground up to seven meters per second. We observe a sharp interface between slow and fast moving fluid after the escarpment, and the interface is moving rapidly up and down. This implies that the position of the maximum velocity standard deviation is elevated a few meters above the surface. Close to the ground the mean wind is reversed relative to the general flow. The results are used to test computational fluid dynamics models for flow over terrain, and has relevance for wind energy. The preliminary comparison shows that the models are incapable of reproducing the reversed flow close to the surface, but more works needs to be done.
Vortex formation and recirculation zones in left anterior descending artery stenoses: computational fluid dynamics analysis
NASA Astrophysics Data System (ADS)
Katritsis, D. G.; Theodorakakos, A.; Pantos, I.; Andriotis, A.; Efstathopoulos, E. P.; Siontis, G.; Karcanias, N.; Redwood, S.; Gavaises, M.
Flow patterns may affect the potential of thrombus formation following plaque rupture. Computational fluid dynamics (CFD) were employed to assess hemodynamic conditions, and particularly flow recirculation and vortex formation in reconstructed arterial models associated with ST-elevation myocardial infraction (STEMI) or stable coronary stenosis (SCS) in the left anterior descending coronary artery (LAD). Results indicate that in the arterial models associated with STEMI, a 50% diameter stenosis immediately before or after a bifurcation creates a recirculation zone and vortex formation at the orifice of the bifurcation branch, for most of the cardiac cycle, thus allowing the creation of stagnating flow. These flow patterns are not seen in the SCS model with an identical stenosis. Post-stenotic recirculation in the presence of a 90% stenosis was evident at both the STEMI and SCS models. The presence of 90% diameter stenosis resulted in flow reduction in the LAD of 51.5% and 35.9% in the STEMI models and 37.6% in the SCS model, for a 10 mmHg pressure drop. CFD simulations in a reconstructed model of stenotic LAD segments indicate that specific anatomic characteristics create zones of vortices and flow recirculation that promote thrombus formation and potentially myocardial infarction.
Mixer assembly for a gas turbine engine having a pilot mixer with a corner flame stabilizing recirculation zone
NASA Technical Reports Server (NTRS)
Dai, Zhongtao (Inventor); Cohen, Jeffrey M. (Inventor); Fotache, Catalin G. (Inventor)
A mixer assembly for a gas turbine engine is provided, including a main mixer, and a pilot mixer having an annular housing in which a corner is formed between an aft portion of the housing and a bulkhead wall in which a corner recirculation zone is located to stabilize and anchor the flame of the pilot mixer. The pilot mixer can further include features to cool the annular housing, including in the area of the corner recirculation zone.
Capture Zone Analyses of Two Airlift Recirculation Wells in the Southern Sector of A/M Area
Aleman, S.E.
This report documents a series of capture zone analyses performed to access the expected overall performance of two (of the twelve) vertical airlift recirculation wells (ARWs) (specifically, SSR-011 and SRR-012) located in the Southern Sector of A/M Area.
The STREON Recirculation Chamber: An Advanced Tool to Quantify Stream Ecosystem Metabolism in the Benthic Zone
NASA Astrophysics Data System (ADS)
Brock, J. T.; Utz, R.; McLaughlin, B.
The STReam Experimental Observatory Network is a large-scale experimental effort that will investigate the effects of eutrophication and loss of large consumers in stream ecosystems. STREON represents the first experimental effort undertaken and supported by the National Ecological Observatory Network (NEON).Two treatments will be applied at 10 NEON sites and maintained for 10 years in the STREON program: the addition of nitrate and phosphate to enrich concentrations by five times ambient levels and electrical fields that exclude top consumers (i.e., fish or invertebrates) of the food web from the surface of buried sediment baskets. Following a 3-5 week period, the sediment baskets will be extracted and incubated in closed, recirculating metabolic chambers to measure rates of respiration, photosynthesis, and nutrient uptake. All STREON-generated data will be open access and available on the NEON web portal. The recirculation chamber represents a critical infrastructural component of STREON. Although researchers have applied such chambers for metabolic and nutrient uptake measurements in the past, the scope of STREON demands a novel design that addresses multiple processes often neglected by earlier models. The STREON recirculation chamber must be capable of: 1) incorporating hyporheic exchange into the flow field to ensure measurements of respiration include the activity of subsurface biota, 2) operating consistently with heterogeneous sediments from sand to cobble, 3) minimizing heat exchange from the motor and external environment, 4) delivering a reproducible uniform flow field over the surface of the sediment basket, and 5) efficient assembly/disassembly with minimal use of tools. The chamber also required a means of accommodating an optical dissolved oxygen probe and a means to inject/extract water. A prototype STREON chamber has been designed and thoroughly tested. The flow field within the chamber has been mapped using particle imaging velocimetry (PIV) under various velocity settings. The extent of exchange with the sediment was assessed by means of a saline tracer injection and adjustment using flow-regulating components was explored. Performance under a broad range of temperatures (1 to 30 ¯C) was assessed. Finally, a novel heat-exchange mechanism meant to minimize warming during operations was evaluated. All prototype assessments demonstrate the applicability of the STREON chamber under a broad range of conditions. Though the STREON recirculation chamber has been designed to satisfy the specific needs of the STREON program, the open-access nature of the NEON network should facilitate scope expansion in the coming decades. The STREON recirculation chamber design and all prototype testing data will be accessible to facilitate chamber use elsewhere. The large number of chamber assemblies required for STREON operations should facilitate the acquisition of units by researchers working outside of the NEON network. Furthermore, the current scope of STREON includes the use of the chambers only once annually, thus a valuable tool for stream ecosystem measurements will be readily available at STREON sites for potential use by researchers interested in such measurements.
Central recirculation zone analysis in an unconfined tangential swirl burner with varying degrees of premixing
NASA Astrophysics Data System (ADS)
Valera-Medina, A.; Syred, N.; Kay, P.; Griffiths, A.
Swirl-stabilised combustion is one of the most widely used techniques for flame stabilisation, uses ranging from gas turbine combustors to pulverised coal-fired power stations. In gas turbines, lean premixed systems are of especial importance, giving the ability to produce low NOx systems coupled with wide stability limits. The common element is the swirl burner, which depends on the generation of an aerodynamically formed central recirculation zone (CRZ) and which serves to recycle heat and active chemical species to the root of the flame as well as providing low-velocity regions where the flame speed can match the local flow velocity. Enhanced mixing in and around the CRZ is another beneficial feature. The structure of the CRZ and hence that of the associated flames, stabilisation and mixing processes have shown to be extremely complex, three-dimensional and time dependent. The characteristics of the CRZ depend very strongly on the level of swirl (swirl number), burner configuration, type of flow expansion, Reynolds number (i.e. flowrate) and equivalence ratio. Although numerical methods have had some success when compared to experimental results, the models still have difficulties at medium to high swirl levels, with complex geometries and varied equivalence ratios. This study thus focuses on experimental results obtained to characterise the CRZ formed under varied combustion conditions with different geometries and some variation of swirl number in a generic swirl burner. CRZ behaviour has similarities to the equivalent isothermal state, but is strongly dependent on equivalence ratio, with interesting effects occurring with a high-velocity fuel injector. Partial premixing and combustion cause more substantive changes to the CRZ than pure diffusive combustion.
Recirculating rotary gas compressor
Weinbrecht, John F. (601 Oakwood Loop, NE., Albuquerque, NM 87123)
A positive displacement, recirculating Roots-type rotary gas compressor which operates on the basis of flow work compression. The compressor includes a pair of large diameter recirculation conduits (24 and 26) which return compressed discharge gas to the compressor housing (14), where it is mixed with low pressure inlet gas, thereby minimizing adiabatic heating of the gas. The compressor includes a pair of involutely lobed impellers (10 and 12) and an associated port configuration which together result in uninterrupted flow of recirculation gas. The large diameter recirculation conduits equalize gas flow velocities within the compressor and minimize gas flow losses. The compressor is particularly suited to applications requiring sustained operation at higher gas compression ratios than have previously been feasible with rotary pumps, and is particularly applicable to refrigeration or other applications requiring condensation of a vapor.
Modelling turbulent recirculating flows in complex geometries
G. D. Tong
The essential features of modeling turbulent flows containing zones of recirculation are discussed. First, the requirement to adequately represent momentum transfer through a shear layer from a main-stream inducing flow to a recirculating (closed streamline) zone. The k-epsilon model is introduced as a minimum global length scale model for this complex flow type in which there is flow separation, a
Rupture Zones of Large South American Earthquakes and Some Predictions
John A. Kelleher
This study attempts to forecast likely locations for large shallow South American earthquakes in the near future by examining the past space-time pattern of occurrence of large (M _ 7.7) earthquakes, the lateral extent of their rupture zones, and, where possible, the direction of rupture propagation. Rupture zones of large shallow earthquakes generally abut and do not overlap. Patterns of
Wind tunnel investigation on the retention of air pollutants in three-dimensional recirculation zones in urban areas
NASA Astrophysics Data System (ADS)
Gomes, Marcos SebastiÐo de Paula; Isnard, AndrÕ Augusto; Pinto, JosÕ MaurÚcio do Carmo
The article discusses an experimental investigation of turbulent dispersion processes in a typical three-dimensional urban geometry, in reduced scale, in neutrally stable conditions. Wind tunnel experiments were carried out for characterizing the flow and the dispersion of a pollutant around a scaled model (1:400) of a group of eight 10-floor buildings surrounding a square. The situation corresponded to the dispersion of fine inertialess particles released from a line source positioned upstream of the urban geometry. After the sudden interruption of the source generation, the particles persisted in the recirculation cavity between the buildings, with the concentration decaying exponentially with time. This is in accordance with previous works on the dispersion process around bluff bodies of different shapes [e.g., Humphries and Vincent, 1976. An experimental investigation of the detention of airborne smoke in the wake bubble behind a disk. Journal of Fluid Mechanics 73, 453-464; Vincent, 1977. Model experiments on the nature of air pollution transport near buildings. Atmospheric Environment 11, 765-774; Fackrell, 1984. Parameters characterizing dispersion in the near wake of buildings. Journal of Wind Engineering and Industrial Aerodynamics 16, 97-118]. The main parameter in the investigation was the characteristic time constant for the concentration decay. The measurements of the variation in the concentration of the fine particles were performed by means of a photo-detection technique based on the attenuation of light. The velocity fields were evaluated with the particle image velocimetry (PIV) technique. The dimensionless residence time H for the particles ( H= ?U/ L, where ? is the time constant for the concentration decay, U the free-stream velocity, and L is a characteristic dimension for the urban geometry, as defined by Humphries and Vincent [1976. An experimental investigation of the detention of airborne smoke in the wake bubble behind a disk. Journal of Fluid Mechanics 73, 453-464] was determined for various locations in the scaled model, in the range of Reynolds numbers ( Re) between 8000 and 64,000. H was found to be 6.5Ý1.0.
Large-eddy simulation of molecular mixing in a recirculating shear flow
NASA Astrophysics Data System (ADS)
Matheou, Georgios
The flow field and mixing in an expansion-ramp geometry is studied using large-eddy simulation (LES) with subgrid scale (SGS) modeling based on the stretched-vortex model. The expansionramp geometry was developed to provide enhanced mixing and flameholding characteristics while maintaining low total-pressure losses, elements that are important in the design and performance of combustors for hypersonic air-breathing propulsion applications. The mixing was studied by tracking a passive scalar without taking into account the effects of chemical reactions and heat release. In order to verify the solver and the boundary closure implementation, a method utilizing results from linear stability analysis (LSA) theory is developed. LSA can be used to compute unstable perturbations to a flow, subject to certain approximations. The perturbations computed from LSA are used as an inflow condition to the flow computed by the solver been assessed. A projection based metric is constructed that only assumes the shape of the solution and not the growth rate of the perturbations, thus also allowing the latter to be determined as part of the verification. The growth rate of the perturbations for an unbounded (effectively) incompressible shear layer and a confined compressible shear layer is found to be in agreement with the prediction of the LSA. The flow and mixing predictions of the LES are in good agreement with experimental measurements. Total (resolved and subgrid) probability density functions (PDFs) of the passive scalar are estimated using an assumed beta-distribution model for the subgrid scalar field. The improved mixing characteristics of the expansion-ramp geometry compared to free shear layers are illustrated by the shapes of the PDFs. Moreover, the temperature rise and the probability of mixed fluid profiles are in good agreement with the experimental measurements, indicating that the mixing on a molecular scale is correctly predicted by the LES-SGS model. Finally, the predictions of the LES are shown to be resolution-independent. The mean fields and passive scalar PDFs have essentially converged at the two finer grid-resolutions used.
Effluent Treatment and Residuals Management Using Land Application to Recycle Nutrients from a Large-Scale Recirculating Aquaculture Facility
Scott Lindell; Roscoe E. Perham
AquaFuture operates a 1.8 million gallon recirculating aquaculture facility capable of filtering the waste products from over three quarters of a million fish that are fed over one million pounds of feed per year. This paper describes a compact system for effluent treatment and residuals management that has proven effective at maintaining water quality within compliance limitations. Solids are removed
Gas turbine combustor stabilization by heat recirculation
NASA Technical Reports Server (NTRS)
Ganji, A.; Short, J.; Branch, M. C.; Oppenheim, A. K.
The feasibility of heat recirculation for stabilization of lean mixtures and emission reduction has been studied in detail for a typical aircraft gas turbine combustor. Thermodynamic calculations have indicated temperature and heat recirculation rates for operation of the combustor over a range of combustion zone equivalence ratios and for varying modes of desired engine operation. Calculations indicate the feasibility of stabilizing the combustion zone at equivalence ratios as low as 0.2 with achievable heat recirculation rates. Detailed chemical kinetic calculations suggest that combustor heat release is maintained with reaction completion substantially before the NO forming reactions, even though CO is rapidly oxidized in this same region.
Confined turbulent swirling recirculating flow predictions. Ph.D. Thesis. Final Report
NASA Technical Reports Server (NTRS)
Abujelala, M. T.; Lilley, D. G.
The capability and the accuracy of the STARPIC computer code in predicting confined turbulent swirling recirculating flows is presented. Inlet flow boundary conditions were demonstrated to be extremely important in simulating a flowfield via numerical calculations. The degree of swirl strength and expansion ratio have strong effects on the characteristics of swirling flow. In a nonswirling flow, a large corner recirculation zone exists in the flowfield with an expansion ratio greater than one. However, as the degree of inlet swirl increases, the size of this zone decreases and a central recirculation zone appears near the inlet. Generally, the size of the central zone increased with swirl strength and expansion ratio. Neither the standard k-epsilon turbulence mode nor its previous extensions show effective capability for predicting confined turbulent swirling recirculating flows. However, either reduced optimum values of three parameters in the mode or the empirical C sub mu formulation obtained via careful analysis of available turbulence measurements, can provide more acceptable accuracy in the prediction of these swirling flows.
Lattice Design for the LHEC Recirculating Linac
Sun, Yipeng; /CERN; Eide, Anders; /CERN; Zimmermann, Frank; /CERN; Adolphsen, Chris; /SLAC
In this paper, we present a lattice design for the Large Hadron Electron Collider (LHeC) recirculating linac. The recirculating linac consists of one roughly 3-km long linac hosting superconducting RF (SRF) accelerating cavities, two arcs and one transfer line for the recirculation. In two passes through a pulsed SRF linac the electron beam can get a maximum energy of 140 GeV. Alternatively, in the Energy Recovery Linac (ERL) option the beam passes through a CW linac four times (two passes for acceleration and two for deceleration) for a maximum energy of 60 GeV.
Chapman, Clark R.
to be an effective approach to reduce NOx emissions in order to meet US2007 and US2010 emissions regulations environmental regulations for diesel engine emissions are becoming increas- ingly stringent, and are driving) and oxides of nitrogen (NOx). The use of exhaust gas recirculation (EGR) coolers is considered
Mechanisms of recirculating liquid flow on distillation sieve plates
Biddulph, M.W. (Univ. of Nottingham (United Kingdom). Dept. of Chemical Engineering); Burton, A.C. (BOC Group, Murray Hill, NJ (United States))
This paper describes an experimental investigation into the phenomenon of flow recirculation on distillation sieve trays. A novel dye injection technique has been applied to a 1.81 m air-water simulation column and has yielded new information concerning the nature of the boundary layer of gas-liquid biphase as it detaches from the column wall. The study has shown that recirculation is strongly influenced by inlet conditions. A critical factor is the underflow clearance between the inlet downcomer apron and the tray floor. As this clearance is increased, the size of the recirculating zones passes through a minimum, indicating the existence of two different mechanisms responsible for the nonuniform flow patterns. A significant implication of this work is that tray designers may minimize the impact of recirculating on mass transfer efficiency by appropriate choice of underflow clearance.
Monitoring of Leachate Recirculation in a Bioreactor Using Electrical Resistivity
NASA Astrophysics Data System (ADS)
Grellier, S.; Bureau, N.; Robain, H.; Tabbagh, A.; Camerlynck, C.; Guerin, R.
The bioreactor is a concept of waste landfill management consisting in speeding up the biodegradation by optimizing the moisture content through leachate recirculation. Electrical resistivity tomography (ERT) is carried out with fast resistivity-meter (Syscal Pro, IRIS Instruments, developed in the framework of the research project CERBERE 01V0665-69, funded by the French Research Ministry) to monitor leachate recirculation. During a recirculation period waste moisture increases, so that electrical resistivity may decrease, but at the same time temperature and mineralization of both waste and leachate become intermixed. If waste temperature is much higher than leachate temperature electrical resistivity will not decrease as much as if the temperature difference was smaller. If leachate mineralization (i.e. leachate conductivity) is higher than that of wet waste in the landfill, electrical resistivity will tend to decrease. Otherwise for example after an addition of rain water into the leachate storage or in case of very wet waste, the resistivities of each medium (leachate and wet waste) can be almost the same, so that leachate mineralization will not have a great influence on waste resistivity. Resistivity measurements were performed during 85 minutes injection trials (with a discharge of 20 m3 h-1) where leachate was injected through a vertical borehole perforated between 1.85 and 4.15 m. Three first measurements are made during the injection (3, 30 and 60 minutes from the beginning of the injection) and the two other after the injection period (8 and 72 minutes after the end of the injection). Apparent and interpreted resistivity variations that occurred during injection trials, expressed as the relative differences (in %) between apparent, respectively interpreted, resistivity during injection and apparent, respectively interpreted, resistivity before injection (reference measurement) show the formation of a plume (a negative anomaly: resistivity decreases with increasing moisture content). The positive anomaly could be explained by an increasing of biogas proportion in waste porosity. For this experiment, leachate temperature is relatively cold (between 5 and 10¯ C, as the injection trials take place at the end of October), leachate conductivity is about 9200 ? S cm-1 (i.e. a resistivity of 1.1 ? m) and waste resistivity in the borehole region is about 80 ? m. This is a situation where the temperature difference between waste and leachate is large and the resistivity difference between waste and leachate is high. The resistivity variation is essentially due to waste moisture increase. ERT method allows leachate diffusion to be seen through the waste mass and the influence zone of the leachate recirculation system to be determined.
High ratio recirculating gas compressor
Weinbrecht, John F. (601 Oakwood Pl., NE., Albuquerque, NM 87123)
A high ratio positive displacement recirculating rotary compressor is disclosed. The compressor includes an integral heat exchanger and recirculation conduits for returning cooled, high pressure discharge gas to the compressor housing to reducing heating of the compressor and enable higher pressure ratios to be sustained. The compressor features a recirculation system which results in continuous and uninterrupted flow of recirculation gas to the compressor with no direct leakage to either the discharge port or the intake port of the compressor, resulting in a capability of higher sustained pressure ratios without overheating of the compressor.
High ratio recirculating gas compressor
Weinbrecht, J.F.
A high ratio positive displacement recirculating rotary compressor is disclosed. The compressor includes an integral heat exchanger and recirculation conduits for returning cooled, high pressure discharge gas to the compressor housing to reducing heating of the compressor and enable higher pressure ratios to be sustained. The compressor features a recirculation system which results in continuous and uninterrupted flow of recirculation gas to the compressor with no direct leakage to either the discharge port or the intake port of the compressor, resulting in a capability of higher sustained pressure ratios without overheating of the compressor. 10 figs.
Exhaust gas recirculation system
Rachedi, S.H.
An engine exhaust gas recirculation (EGR) system is provided in which a sonic flow EGR valve is moved to open positions to establish a different constant rate of flow at each open position of the EGR valve in response to air pressure acting on a servo means secured to the valve, the air pressure force being controlled by changes in a control vacuum opposing the air pressure force and modified by an air bleed device as a function of changes in engine exhaust gas backpressure levels, to provide an EGR valve movement that varies essentially in proportion to changes in engine air flow.
Cooling Along Hyporheic Pathlines in a Large River Riparian Zone
Floodplains can contribute to hyporheic cooling and moderation of temperature for rivers, but extent and magnitude are dependent on ground water hydrology. Here we illustrate the controls and dynamics of hyporheic cooling in the ground water of a large river floodplain with field...
Recirculation in venovenous extracorporeal membrane oxygenation.
Abrams, Darryl; Bacchetta, Matthew; Brodie, Daniel
Recirculation, a phenomenon in which reinfused oxygenated blood is withdrawn by the drainage cannula without passing through the systemic circulation, decreases the efficiency with which venovenous extracorporeal membrane oxygenation (ECMO) provides oxygenation. The precise amount of recirculation may be difficult to quantify. However, interventions should be attempted to reduce recirculation when oxygen delivery is suboptimal and recirculation is suspected. Several techniques, including the use of dual-lumen cannulae, have been successful in minimizing recirculation in venovenous ECMO. This article will provide an overview of the factors that affect recirculation, methods that may be used to quantify recirculation, and interventions that may reduce recirculation, thereby increasing ECMO efficiency. PMID:25423117
Quiet zone within a seismic gap near western Nicaragua: Possible location of a future large earthquake
Harlow, D.H.; White, R.A.; Cifuentes, I.L.; Aburto, Q.A.
A 5700-square-kilometer quiet zone occurs in the midst of the locations of more than 4000 earthquakes off the Pacific coast of Nicaragua. The region is indicated by the seismic gap technique to be a likely location for an earthquake of magnitude larger than 7. The quiet zone has existed since at least 1950; the last large earthquake originating from this area occurred in 1898 and was of magnitude 7.5. A rough estimate indicates that the magnitude of an earthquake rupturing the entire quiet zone could be as large as that of the 1898 event. It is not yet possible to forecast a time frame for the occurrence of such an earthquake in the quiet zone. Copyright ?? 1981 AAAS.
The Evolution and Natural State of Large-Scale Vapor-Dominated Zones
Ingebritsen, S.E.
Numerical simulation is used to define the rather special conditions under which large-scale vapor-dominated zones can evolve. Given an adequate supply of heat, a vapor-dominated zone can evolve within low-permeability barriers without changes in rock properties or boundary conditions. However, the evolution of the system is accelerated in cases involving an initially high fluid throughflow rate that decreases with time. Near-steady-state pressures within the vapor-dominated zone are shown to vary with depth to the caprock.
Combustion-gas recirculation system
Baldwin, Darryl Dean (Lacon, IL)
A combustion-gas recirculation system has a mixing chamber with a mixing-chamber inlet and a mixing-chamber outlet. The combustion-gas recirculation system may further include a duct connected to the mixing-chamber inlet. Additionally, the combustion-gas recirculation system may include an open inlet channel with a solid outer wall. The open inlet channel may extend into the mixing chamber such that an end of the open inlet channel is disposed between the mixing-chamber inlet and the mixing-chamber outlet. Furthermore, air within the open inlet channel may be at a pressure near or below atmospheric pressure.
Modeling of leachate recirculation using vertical wells in bioreactor landfills.
Feng, Shi-Jin; Cao, Ben-Yi; Zhang, Xu; Xie, Hai-Jian
Leachate recirculation (LR) in municipal solid waste (MSW) landfills operated as bioreactors offers significant economic and environmental benefits. The subsurface application method of vertical wells is one of the most common LR techniques. The objective of this study was to develop a novel two-dimensional model of leachate recirculation using vertical wells. This novel method can describe leachate flow considering the effects of MSW settlement while also accounting separately for leachate flow in saturated and unsaturated zones. In this paper, a settlement model for MSW when considering the effects of compression and biodegradation on the MSW porosity was adopted. A numerical model was proposed using new governing equations for the saturated and unsaturated zones of a landfill. The following design parameters were evaluated by simulating the recirculated leachate volume and the influence zones of waste under steady-state flow conditions: (1) the effect of MSW settlement, (2) the effect of the initial void ratio, (3) the effect of the injected head, (4) the effect of the unit weight, (5) the effect of the biodegradation rate, and (6) the effect of the compression coefficient. The influence zones of LR when considering the effect of MSW settlement are smaller than those when neglecting the effect. The influence zones and LR volume increased with an increase in the injection pressure head and initial void ratio of MSW. The proposed method and the calculation results can provide important insight into the hydrological behavior of bioreactor landfills. PMID:25874416
Bounds on strain in large Tertiary shear zones of SE Asia from boudinage restoration
NASA Astrophysics Data System (ADS)
Lacassin, R.; Leloup, P. H.; Tapponnier, P.
We have used surface-balanced restoration of stretched, boudinaged layers to estimate minimum amounts of finite strain in the mylonitic gneisses of the Oligo-Miocene Red River-Ailao Shan shear zone (Yunnan, China) and of the Wang Chao shear zone (Thailand). The layer-parallel extension values thus obtained range between 250 and 870%. We discuss how to use such extension values to place bounds on amounts of finite shear strain in these large crustal shear zones. Assuming simple shear, these values imply minimum total and late shear strains of, respectively, 33 Ý 6 and 7 Ý 3 at several sites along the Red River-Ailao Shan shear zone. For the Wang Chao shear zone a minimum shear strain of 7 Ý 4 is deduced. Assuming homogeneous shear would imply that minimum strike-slip displacements along these two left-lateral shear zones, which have been interpreted to result from the India-Asia collision, have been of the order of 330 Ý 60 km (Red River-Ailao Shan) and 35 Ý 20 km (Wang Chao).
Large-scale folding in the upper part of the Ivrea-Verbano zone, NW Italy
NASA Astrophysics Data System (ADS)
Rutter, Ernest; Brodie, Katharine; James, Tony; Burlini, Luigi
New geological mapping has led to a new interpretation of the large-scale superimposed folding in the upper part of the Ivrea-Verbano zone, Italian Alps. The region is widely held to represent an upended section through lower continental crust of northern Italy. The dominant fold structure, extending some 40 km along strike, is the Massone tight to isoclinal antiform, with a hinge line strongly curved through 115¯. This folds pre-existing large-scale folds that formed during regional migmatization, probably during the Hercynian orogeny, to form a type-2 interference geometry. The region then suffered post-orogenic mafic magmatic underplating and other magmatism, accompanied by crustal stretching, with contact metamorphism and migmatization causing the imposition of the final pattern of metamorphic isograds. The Ivrea-Verbano zone was brought into contact with the overlying metamorphic rocks of the Serie dei Laghi on a major shear zone. Sub-solidus stretching continued though displacements on low-angle, high-temperature shear zones. Most of the Ivrea-Verbano zone was finally tilted to the vertical and emplaced into its present position after the Mesozoic era and probably during Alpine orogenesis, forming the vertical limb of a crustal-scale double kink.
Seismic gaps and source zones of recent large earthquakes in coastal Peru
Dewey, J.W.; Spence, W.
The earthquakes of central coastal Peru occur principally in two distinct zones of shallow earthquake activity that are inland of and parallel to the axis of the Peru Trench. The interface-thrust (IT) zone includes the great thrust-fault earthquakes of 17 October 1966 and 3 October 1974. The coastal-plate interior (CPI) zone includes the great earthquake of 31 May 1970, and is located about 50 km inland of and 30 km deeper than the interface thrust zone. The occurrence of a large earthquake in one zone may not relieve elastic strain in the adjoining zone, thus complicating the application of the seismic gap concept to central coastal Peru. However, recognition of two seismic zones may facilitate detection of seismicity precursory to a large earthquake in a given zone; removal of probable CPI-zone earthquakes from plots of seismicity prior to the 1974 main shock dramatically emphasizes the high seismic activity near the rupture zone of that earthquake in the five years preceding the main shock. Other conclusions on the seismicity of coastal Peru that affect the application of the seismic gap concept to this region are: (1) Aftershocks of the great earthquakes of 1966, 1970, and 1974 occurred in spatially separated clusters. Some clusters may represent distinct small source regions triggered by the main shock rather than delimiting the total extent of main-shock rupture. The uncertainty in the interpretation of aftershock clusters results in corresponding uncertainties in estimates of stress drop and estimates of the dimensions of the seismic gap that has been filled by a major earthquake. (2) Aftershocks of the great thrust-fault earthquakes of 1966 and 1974 generally did not extend seaward as far as the Peru Trench. (3) None of the three great earthquakes produced significant teleseismic activity in the following month in the source regions of the other two earthquakes. The earthquake hypocenters that form the basis of this study were relocated using station adjustments computed by the method of joint hypocenter determination. ?? 1979 Birkha??user Verlag.
An autostereoscopic display with high resolution and large number of view zones
NASA Astrophysics Data System (ADS)
Chen, Wu-Li; Hsu, Wei-Liang; Tsai, Chao-Hsu; Wang, Chy-Lin; Wu, Chang-Shuo; Yang, Jinn-Cherng; Cheng, Shu-Chuan
For a spatial-multiplexed 3D display, trade-off between resolution and number of view-zones are usually unavoidable due to the limited number of pixels on the screen. In this paper, we present a new autostereoscopic system, named as "integrated-screen system," to substantially increase the total number of pixels on the screen, which in turn increase both the resolution and number of view-zones. In the integrated-screen system, a large number of mini-projectors are arrayed and the images are tiled together without seams in between. For displaying 3D images, the lenticular screen with predesigned tilted angle is used for distributing different viewing zones. In order to achieve good performance, we design a brand-new projector with special lens set to meet the low-distortion requirement because the distortion of the image will induce serious crosstalk between view-zones. The proposed system has two advantages. One is the extensibility of the screen size. The size of the display can be chosen based on the applications we deal with, including the size of the projected pixel and the number of viewing zones. The other advantage is that the integrated-screen system provides projected pixels in great density to solve the major problem of the poor resolution that a lenticular-type 3D display has.
Large-scale folding in the upper part of the Ivrea-Verbano zone, NW Italy
Ernest Rutter; Katharine Brodie; Tony James; Luigi Burlini
New geological mapping has led to a new interpretation of the large-scale superimposed folding in the upper part of the Ivrea-Verbano zone, Italian Alps. The region is widely held to represent an upended section through lower continental crust of northern Italy. The dominant fold structure, extending some 40km along strike, is the Massone tight to isoclinal antiform, with a hinge
Integrated Dynamic Aquaculture and Wastewater Treatment Modelling for Recirculating Aquaculture Systems
Torsten E. I. Wika; Bjorn T. Lind
Recirculating aquaculture systems (RAS) in land based sh tanks, where the sh tank euen t is biologically treated and then recirculated back to the sh tanks, of- fers a possibility for large scale ecologically sustainable sh production. In order to fully exploit the advantages of RAS, however, the water exchange should be as small as possible. This implies strong demands
Integrated dynamic aquaculture and wastewater treatment modelling for recirculating aquaculture systems
Torsten E. I. Wik; Bj—rn T. LindÕn; Per I. Wramner
Recirculating aquaculture systems (RAS) in land based fish tanks, where the fish tank effluent is biologically treated and then recirculated back to the fish tanks, offers a possibility for large scale ecologically sustainable fish production. In order to fully exploit the advantages of RAS, however, the water exchange should be as small as possible. This implies strong demands on the
Geometrical and material properties of large transform fault zone structures (Invited)
NASA Astrophysics Data System (ADS)
Ben-Zion, Y.
The degree of strain localization in the brittle crust depends on rheology, boundary conditions, pre-existing heterogeneities and inherited large-scale-structures (e.g. lithological contrasts). For cases with weakening rheology, stress boundary conditions and moderate initial heterogeneities, the results depend on the ratio Q of loading rate over damage healing rate. Relatively high Q values lead to progressive development with increasing slip of geometrically regular structures, while relatively low Q values produce persisting disordered fault zones (Ben-Zion et al. 1999; Lyakhovsky et al. 2001). The fault zone damage follows generally a flower structure with significant damage only in the top few km of the crust (Ben-Zion and Shi 2005; Ma 2008; Finzi et al. 2009). Large-scale heterogeneities (e.g. changes of Moho depth and large stepovers) can produce distributed structures with significant damage at depth (Finzi et al. 2009; Lyakhovsky and Ben-Zion 2009). Systematic analyses of seismic fault zone trapped waves indicate that the trapping structures are associated typically with ~100 m wide layers that extend generally only to ~3.5 km depth and are characterized by 30-50% velocity reduction and strong attenuation (e.g., Ben-Zion et al. 2003; Peng et al. 2003; Lewis and Ben-Zion this meeting). The trapping structures are surrounded by broader anisotropic and scattering zones limited primarily also to the shallow crust (e.g., Boness and Zoback 2004; Peng and Ben-Zion 2004, 2006). Contrasts of elastic properties across faults tend to suppress branching and produce strong along-strike asymmetry of rupture properties, with larger slip-velocity and slip in the direction of particle motion in the compliant solid (e.g., Ben-Zion 2001; Ampuero and Ben-Zion 2008; Brietzke et al. 2009). This leads to strongly asymmetric damage across the fault, with more damage on the stiffer side (Ben-Zion and Shi 2005). Systematic analyses of head waves along several sections of the San Andreas, Calaveras and Hayward faults reveal bimaterial interfaces that extend to the bottom of the seismogenic zone, with velocity contrasts of 20% or more in the top ~3 km and lower contrasts of 5-15% in the deeper section (e.g., Ben-Zion et al. 1992; McGuire and Ben-Zion 2005; Lewis et al. 2007; Zhao and Peng 2008). In several places, analyses of seismic fault zone waves and geological data indicate that the shallow damaged layers are asymmetric across the fault, as expected for ruptures along a bimaterial interface (Lewis et al. 2005, 2007; Dor et al. 2006, 2008; Wechsler et al. 2009).
ROSSBY WAVES ON A SHEAR FLOW WITH RECIRCULATION CORES Oleg G. Derzho1 and Roger Grimshaw2 1 Large amplitude Rossby waves riding on a background flow with a weak shear can be calculated up Introduction Rossby waves are a fundamental component of planetary scale atmospheric and oceanic flows
Solar Sail - Fresnel Zone Plate Lens for a Large Space Based Telescope
Early, J T
A Fresnel zone plate lens made with solar sail material could be used as the primary optic for a very large aperture telescope on deep space probes propelled by solar sails. The large aperture telescope capability could enable significant science on fly-by missions to the asteroids, Pluto, Kuiper belt or the tort cloud and could also enable meaningful interstellar fly-by missions for laser propelled sails. This type of lens may also have some potential for laser communications and as a solar concentrator. The techniques for fabrication of meter size and larger Fresnel phase plate optics are under development at LLNL, and we are extending this technology to amplitude zone plates made from sail materials. Corrector optics to greatly extend the bandwidth of these Fresnel optics will be demonstrated in the future. This novel telescope concept will require new understanding of the fabrication, deployment and control of gossamer space structures. It will also require new materials technology for fabricating these optics and understanding their long term stability in a space environment.
Transition and acoustic response of recirculation structures in an unconfined co-axial isothermal swirling flow
NASA Astrophysics Data System (ADS)
Santhosh, R.; Miglani, Ankur; Basu, Saptarshi
This paper reports the first observations of transition from a pre-vortex breakdown (Pre-VB) flow reversal to a fully developed central toroidal recirculation zone in a non-reacting, double-concentric swirling jet configuration and its response to longitudinal acoustic excitation. This transition proceeds with the formation of two intermediate, critical flow regimes. First, a partially penetrated vortex breakdown bubble (VBB) is formed that indicates the first occurrence of an enclosed structure as the centre jet penetration is suppressed by the growing outer roll-up eddy; resulting in an opposed flow stagnation region. Second, a metastable transition structure is formed that marks the collapse of inner mixing vortices. In this study, the time-averaged topological changes in the coherent recirculation structures are discussed based on the non-dimensional modified Rossby number (Rom) which appears to describe the spreading of the zone of swirl influence in different flow regimes. Further, the time-mean global acoustic response of pre-VB and VBB is measured as a function of pulsing frequency using the relative aerodynamic blockage factor (i.e., maximum radial width of the inner recirculation zone). It is observed that all flow modes except VBB are structurally unstable as they exhibit severe transverse radial shrinkage (20%) at the burner Helmholtz resonant modes (100-110 Hz). In contrast, all flow regimes show positional instability as seen by the large-scale, asymmetric spatial shifting of the vortex core centres. Finally, the mixing transfer function M (f) and magnitude squared coherence ?2(f) analysis is presented to determine the natural coupling modes of the system dynamic parameters (u', p'), i.e., local acoustic response. It is seen that the pre-VB flow mode exhibits a narrow-band, low pass filter behavior with a linear response window of 100-105 Hz. However, in the VBB structure, presence of critical regions such as the opposed flow stagnation region alters the linearity range with the structure showing a response even at higher pulsing frequencies (100-300 Hz).
Ozonation followed by ultraviolet irradiation provides effective bacteria inactivation in a freshwater recirculating system
Technology Transfer Automated Retrieval System (TEKTRAN)
Recirculating aquaculture systems may require an internal disinfection process to control population growth of pathogens and heterotrophic bacteria. Ozonation and ultraviolet (UV) irradiation are two technologies that have been used to treat relatively large aquaculture flows, including flows withi...
Desert - A Multi-scale Study of A Large Active Shear Zone, The Dead Sea Transform
NASA Astrophysics Data System (ADS)
Weber, M.; Ben-Avraham, Z.; Abu-Ayyyash, K.; El-Kelani, R.; Desert Group
How do shear zones work and what controls them ? To be able to address this central question of plate tectonics, the DEad SEa Rift Transect (DESERT) group performed an interdisciplinary and multi-scale study of the Dead Sea Rift. DESERT consists of several coincident seismic, magnetotelluric and seismological sub-projects performed by partners from Germany, Israel, Jordan and Palestine. The Dead Sea Rift / Dead Sea Transform acts as the hinge between the Alpine- Himalayan mountain belt and the Afro-Arabian rift system and has a left-lateral mo- tion of about 105 km as of today. The nearly linear structure of this world geological site provides a natural laboratory to study large active faults. The key to understand- ing the geodynamics and plate tectonics in this region, is a detailed knowledge of the crustal and upper mantle structure on scales from plate tectonics to meters. This presentation will give an overview of the results of the seismic/seismological and magnetotelluric sub-projects of DESERT: (a) Wide-angle reflection/refraction; (b) Near-vertical reflection; (c) Controlled source array; (d) Passive seismological array; (e) Magnetotelluric pilot-study. One result on the plate tectonic scale is that the Moho depth gradually increases from 28 to 38 km along the profile, but that no Moho updoming is observed under the "rift". Therefore it seems that the mantle only played a minor role in the extension process associated with the rift. On the meter scale it was possible to excite fault guided waves which indicate that the low-velocity zone associated with the fault zone shows a velocity reduction of 10 to 25 %, but only a width of 10 to 20 meters.
DESERT - A multi-scale study of a large active shear zone, the Dead Sea Transform
NASA Astrophysics Data System (ADS)
Weber, M.; Ben-Avraham, Z.; Abu-Ayyash, K.; El-Kelani, R.
How do shear zones work and what controls them ? To be able to address this central question of plate tectonics, the DEad SEa Rift Transect (DESERT) group performed an interdisciplinary and multi-scale study of the Dead Sea Rift. DESERT consists of several coincident seismic, magnetotelluric and seismological sub-projects performed by partners from Germany, Israel, Jordan and Palestine. The Dead Sea Rift / Dead Sea Transform acts as the hinge between the Alpine-Himalayan mountain belt and the Afro-Arabian rift system and has a left-lateral motion of about 105 km as of today. The nearly linear structure of this world geological site provides a natural laboratory to study large active faults. The key to understanding the geodynamics and plate tectonics in this region, is a detailed knowledge of the crustal and upper mantle structure on scales from plate tectonics to meters. This presentation will give an overview of the results of the seismic/seismological and magnetotelluric sub-projects of DESERT: (a) Wide-angle reflection/refraction; (b) Near-vertical reflection; (c) Controlled source array; (d) Passive seismological array; (e) Magnetotelluric pilot-study. One result on the plate tectonic scale is that the Moho depth gradually increases from 28 to 38 km along the profile, but that no Moho updoming is observed under the "rift". Therefore it seems that the mantle only played a minor role in the extension process associated with the rift. On the meter scale it was possible to excite fault guided waves which indicate that the low-velocity zone associated with the fault zone shows a velocity reduction of 10 to 25 %, but only a width of 10 to 20 meters.
Modelling stream flow for use in ecological studies in a large, arid zone river, central Australia
NASA Astrophysics Data System (ADS)
Costelloe, Justin F.; Grayson, Rodger B.; McMahon, Thomas A.
Australian arid zone ephemeral rivers are typically unregulated and maintain a high level of biodiversity and ecological health. Understanding the ecosystem functions of these rivers requires an understanding of their hydrology. These rivers are typified by highly variable hydrological regimes and a paucity, often a complete absence, of hydrological data to describe these flow regimes. A daily time-step, grid-based, conceptual rainfall-runoff model was developed for the previously uninstrumented Neales River in the arid zone of northern South Australia. Hourly, logged stage data provided a record of stream-flow events in the river system. In conjunction with opportunistic gaugings of stream-flow events, these data were used in the calibration of the model. The poorly constrained spatial variability of rainfall distribution and catchment characteristics (e.g. storage depths) limited the accuracy of the model in replicating the absolute magnitudes and volumes of stream-flow events. In particular, small but ecologically important flow events were poorly modelled. Model performance was improved by the application of catchment-wide processes replicating quick runoff from high intensity rainfall and improving the area inundated versus discharge relationship in the channel sections of the model. Representing areas of high and low soil moisture storage depths in the hillslope areas of the catchment also improved the model performance. The need for some explicit representation of the spatial variability of catchment characteristics (e.g. channel/floodplain, low storage hillslope and high storage hillslope) to effectively model the range of stream-flow events makes the development of relatively complex rainfall-runoff models necessary for multisite ecological studies in large, ungauged arid zone catchments. Grid-based conceptual models provide a good balance between providing the capacity to easily define land types with differing rainfall-runoff responses, flexibility in defining data output points and a parsimonious water-balance-routing model.
Chronology of historical tsunamis in Mexico and its relation to large earthquakes along the subduction zone
NASA Astrophysics Data System (ADS)
Suarez, G.; Mortera, C.
The chronology of historical earthquakes along the subduction zone in Mexico spans a time period of approximately 400 years. Although the population density along the coast of Mexico has always been low, relative to that of central Mexico, several of the large subduction earthquakes reports include references to the presence of tsunamis invading the southern coast of Mexico. Here we present a chronology of historical tsunamis affecting the Pacific coast of Mexico and compare this with the historical record of subduction events and to the existing Mexican and worldwide catalogs of tsunamis in the Pacific basin. Due to the geographical orientation of the Pacific coat of Mexico, tsunamis generated on the other subduction zones of the Pacific have not had damaging effects in the country. Among the tsunamis generated by local earthquakes, the largest one by far is the one produced by the earthquake of 28 March 1787. The reported tsunami has an inundation area that reaches for over 6 km inland. The length of the coast where the tsunami was reported extends for over 450 km. In the last 100 years two large tsunamis have been reported along the Pacific coast of Mexico. On 22 June 1932 a tsunami with reported wave heights of up to 11 m hit the coast of Jalisco and Colima. The town of Cuyutlan was heavily damaged and approximately 50 people lost their lives do to the impact of the tsunami. This unusual tsunami was generated by an aftershock (M 6.9) of the large 3 June 1932 event (M 8.1). The main shock of 3 June did not produce a perceptible tsunami. It has been proposed that the 22 June event is a tsunami earthquake generated on the shallow part of the subduction zone. On 16 November 1925 an unusual tsunami was reported in the town of Zihuatanejo in the state of Guerrero, Mexico. No earthquake on the Pacific rim occurs at the same time as this tsunami and the historical record of hurricanes and tropical storms do not list the presence of a meteorological disturbance that could explain a surge wave of the height reported. Here we investigate the morphology of the trench in this region to analyze whether a local landslide on the trench slope or in the continental shelf could be the cause of this tsunami.
Groundwater in the Earth's critical zone: Relevance to large-scale patterns and processes
NASA Astrophysics Data System (ADS)
Fan, Ying
Although we have an intuitive understanding of the behavior and functions of groundwater in the Earth's critical zone at the scales of a column (atmosphere-plant-soil-bedrock), along a toposequence (ridge to valley), and across a small catchment (up to third-order streams), this paper attempts to assess the relevance of groundwater to understanding large-scale patterns and processes such as represented in global climate and Earth system models. Through observation syntheses and conceptual models, evidence are presented that groundwater influence is globally prevalent, it forms an environmental gradient not fully captured by the climate, and it can profoundly shape critical zone evolution at continental to global scales. Four examples are used to illustrate these ideas: (1) groundwater as a water source for plants in rainless periods, (2) water table depth as a driver of plant rooting depth, (3) the accessibility of groundwater as an ecological niche separator, and (4) groundwater as the lower boundary of land drainage and a global driver of wetlands. The implications to understanding past and future global environmental change are briefly discussed, as well as critical discipline, scale, and data gaps that must be bridged in order for us to translate what we learn in the field at column, hillslope and catchment scales, to what we must predict at regional, continental, and global scales.
Contamination of port zone sediments by metals from Large Marine Ecosystems of Brazil.
Buruaem, Lucas M; Hortellani, Marcos A; Sarkis, Jorge E; Costa-Lotufo, Leticia V; Abessa, Denis M S
Sediment contamination by metals poses risks to coastal ecosystems and is considered to be problematic to dredging operations. In Brazil, there are differences in sedimentology along the Large Marine Ecosystems in relation to the metal distributions. We aimed to assess the extent of Al, Fe, Hg, Cd, Cr, Cu, Ni, Pb and Zn contamination in sediments from port zones in northeast (Mucuripe and PecÕm) and southeast (Santos) Brazil through geochemical analyses and sediment quality ratings. The metal concentrations found in these port zones were higher than those observed in the continental shelf or the background values in both regions. In the northeast, metals were associated with carbonate, while in Santos, they were associated with mud. Geochemical analyses showed enrichments in Hg, Cd, Cu, Ni and Zn, and a simple application of international sediment quality guidelines failed to predict their impacts, whereas the use of site-specific values that were derived by geochemical and ecotoxicological approaches seemed to be more appropriate in the management of the dredged sediments. PMID:22306311
Recirculation in multiple wave conversions
Kaufman, A. N.; Brizard, A.J.; Kaufman, A.N.; Tracy, E.R.
A one-dimensional multiple wave-conversion model is constructed that allows energy recirculation in ray phase space. Using a modular eikonal approach, the connection coefficients for this model are calculated by ray phase-space methods. Analytical results (confirmed numerically) show that all connection coefficients exhibit interference effects that depend on an interference phase, calculated from the coupling constants and the area enclosed by the intersecting rays. This conceptual model, which focuses on the topology of intersecting rays in phase space, is used to investigate how mode conversion between primary and secondary waves is modified by the presence of a tertiary wave.
21 CFR 880.5045 - Medical recirculating air cleaner.
Code of Federal Regulations, 2011 CFR
...2011-04-01 false Medical recirculating air cleaner. 880.5045 Section 880.5045 ...880.5045 Medical recirculating air cleaner. (a) Identification. A medical recirculating air cleaner is a device used to remove...
Denitrification in recirculating systems: Theory and applications
Jaap van Rijn; Yossi Tal; Harold J. Schreier
Profitability of recirculating systems depends in part on the ability to manage nutrient wastes. Nitrogenous wastes in these systems can be eliminated through nitrifying and denitrifying biofilters. While nitrifying filters are incorporated in most recirculating systems according to well-established protocols, denitrifying filters are still under development. By means of denitrification, oxidized inorganic nitrogen compounds, such as nitrite and nitrate are
Isotopic variation of fishes in freshwater and estuarine zones of a large subtropical coastal lagoon
NASA Astrophysics Data System (ADS)
Garcia, A. M.; Hoeinghaus, D. J.; Vieira, J. P.; Winemiller, K. O.
We used stable C and N isotope ratios of tissues from 29 fish species from a large subtropical lagoon in southern Brazil to examine spatial variability in isotopic composition and vertical trophic structure across freshwater and estuarine habitats. Nitrogen isotope ratios indicated a smooth gradation in trophic positions among species, with most fishes occupying the secondary and tertiary consumer level. Fish assemblages showed a significant shift in their carbon isotopic signatures between freshwater and estuarine sites. Depleted carbon signatures (from -24.7 to -17.8) were found in freshwater, whereas more enriched signatures (from -19.1 to -12.3) were obtained within the estuarine zone downstream. Based on our survey of the C 3 and C 4 plants and isotopic values for phytoplankton and benthic microalgae reported for ecosystems elsewhere, we hypothesized that the observed ?13C differences in the fish assemblage between freshwater and estuarine sites is due to a shift from assimilating organic matter ultimately derived from C 3 freshwater marsh vegetation and phytoplankton at the freshwater site ( ?13C ranging from -25 to -19), to C 4 salt-marsh (e.g. Spartina) and widgeon grass ( Ruppia maritima), benthic microalgae and marine phytoplankton at the estuarine sites (from -18 to -12). Our results suggested that fish assemblages are generally supported by autochthonous primary production. Freshwater fishes that likely were displaced downstream into the estuary during periods of high freshwater discharge had depleted ?13C values that were characteristic of the upper lagoon. These results suggest that spatial foodweb subsidies can occur within the lagoon.
Initial water budget: the key to detaching large volumes of eclogitized oceanic crust in subduction zones?
NASA Astrophysics Data System (ADS)
Angiboust, Samuel; Agard, Philippe
The Mesozoic, Neotethyan ophiolites and eclogites from the Zermatt-Saas area (ZS, Western Alps) represent a complete sequence of subducted lithosphere and the largest and deepest known piece of exhumed oceanic lithosphere so far (Bucher et al., 2005; Angiboust et al., 2009). Pervasive hydrothermal processes and seafloor alteration, which led to the incorporation of large amounts of fluid bound in the hydrated, upper layers of the oceanic crust, enabled the development of moderately (lawsonite eclogites) or strongly hydrated parageneses (glaucophanites, chloritoschists). Although their exhumation may have been facilitated by the highly buoyant continental units underlying the ZS ophiolite (e.g., Monte Rosa) and/or the mechanically weak (and light) surrounding serpentinites, none of the other major ophiolite bodies from the same subduction zone (eg, Monviso, Voltri) show the same characteristics (ie, continuous mafic slices and abundant lawsonite). We therefore investigated the extent to which the hydration of the oceanic lithosphere may be a major parameter controlling exhumation, a process largely overlooked up to now. Internally, the ZS ophiolite is made up of a series of tectonics slices of oceanic crust (150-300m thick) which are systematically separated by a 5 to 100-m thick serpentinite slivers. This stack of slices is separated from the underlying eclogitized continental crust (e.g., Monte Rosa) by a thick (~500m) serpentinite sole. Field observations, textural relationships and pseudosection modelling reveal that lawsonite (now pseudomorphed by clinozoisite) was abundant and widespread in mafic eclogites when the ophiolite detached from the slab at c. 550¯C and 24 kbar. Comparison between fresh eclogitic samples and thermodynamic modelling suggests that (i) water remained in excess from burial to eclogitic peak conditions, (ii) the lightest eclogitized metabasalts correspond to the portions of oceanic crust where metasomatism was most intense, (iii) crystallization of widespread hydrated parageneses (such as lawsonite, glaucophane and phengite), instead of garnet and omphacite, decreased rock density by 5 to 10 % and subsequently enhanced its flottability. We propose that this density decrease acted as an efficient force to prevent these slices from irreversibly sinking into the mantle. Penetrative serpentinization of the slab mantle harzburgites during ridge-processes (Li et al., 2004) likely facilitated the detachment of theses slices from the downgoing slab and their stacking in the serpentinized subduction channel at pressures between 15-20 kbar. Exhumation of the underlying positively buoyant continental crust later dragged this "frozen" nappe-stack towards the surface.
Recovery of coastal ecosystems after large tsunamis in various climatic zones - review of cases from tropical, temperate and polar zones (Invited)
NASA Astrophysics Data System (ADS)
Szczucinski, W.
Large tsunamis cause significant changes in coastal ecosystems. They include modifications in shoreline position, sediment erosion and deposition, new initial soil formation, salination of soils and waters, removal of vegetation, as well as direct impact on humans and infrastructure. The processes and rate of coastal zone recovery from large tsunamis has been little studied but during the last decade a noteworthy progress has been made. This study focus on comparison of recovery processes in various climatic zones, namely in monsoonal-tropical, temperate and polar zone. It is based on own observation and monitoring in areas affected by 2004 Indian Ocean Tsunami in Thailand, 2011 Tohoku-oki tsunami in Japan and 2000 Paatuut landslide-generated tsunami in Vaigat Strait (west Greenland), as well as on review of published studies from those areas. The particular focus is on physical and biological recoveries of beaches, recovery of coastal vegetation, new soil formation in eroded areas and those covered by tsunami deposits, marine salt removal from soils, surface- and groundwater, as well as landscape adjustment after the tsunamis. The beach zone - typically the most tsunami-eroded zone, has been recovered already within weeks to months and has been observed to be in the pre-tsunami equilibrium stage within one year in all the climate zones, except for sediment-starved environments. The existing data on beach ecosystems point also to relatively fast recovery of meio- and macrofauna (within weeks to several months). The recovery of coastal vegetation depends on the rate of salt removal from soils or on the rate of soil formation in case of its erosion or burial by tsunami deposits. The salt removal have been observed to depend mainly on precipitation and effective water drainage. In tropical climate with seasonal rainfall of more 3000 mm the salt removal was fast, however, in temperate climate with lower precipitation and flat topography the salinities still exceeded the recommended concentrations for freshwater plants after one year. The new soil formation and vegetation recovery depends mainly on the rate of biological production. In tropical climate the vegetation largely recovered already after the first rainy season and supported the new soil formation. In temperate climate this process was much slower, in particular in flat lying areas and on coastal dunes with poor sandy soils. In polar climate only limited vegetation recovery (mainly of Salix species) has been observed after 12 years and vegetation withered due to salt stress still marked the tsunami inundation limit and the new soil formation was very slow and focused on low lying, wet areas buried with thin tsunami deposits cover. The post-tsunami recovery processes may be grouped into climate-related (vegetation recovery, removal of salts from soils) and non climate-related (e.g. beach recovery) or modified by climatic and local factors (for instance, the rate of tsunami deposits reworking and thus new soil formation). The rate of recovery varies from days / weeks as in case of beach recovery to several decades as in case of new soil formation on tsunami deposits. The study was partly funded by Polish National Science Centre grant No. 2011/01/B/ST10/01553. The review results from studies in collaboration with number of researchers from Australia, Japan, Poland, Thailand, United Kingdom and United States to whom I express sincere thanks.
Determining fault zone structure and examining earthquake early warning signals using large datasets of seismograms
NASA Astrophysics Data System (ADS)
Lewis, Michael Antony
Seismic signals associated with near-fault waveforms are examined to determine fault zone structure and scaling of earthquake properties with event magnitude. The subsurface structure of faults is explored using fault zone head and/or trapped waves, while various signals from the early parts of seismograms are investigated to find out the extent to which they scale with magnitude. Fault zone trapped waves are observed in three arrays of instruments across segments of the San Jacinto fault. Similarly to previous fault zone trapped wave studies, the low velocity damage zones are found to be 100-200m wide and extend to a depth of 3-5km. Observation and modeling indicate that the damage zone was asymmetric around the fault trace. A similar sense of damage asymmetry was observed using detailed geological mapping by Dor et al. (2006) nearby on the San Jacinto fault at Anza. Travel time analysis and arrival time inversions of fault zone head waves were used to produce high resolution images of the fault structure of the San Andreas fault south of Hollister. The contrast of P wave velocities across the fault was found to be 50% in the shallow section, lowering to 10-20% below 3 km, with the southwest side having faster velocities. Inversions making use of different subsets of stations suggest that a low velocity damage zone also exists in this area and that it is more prominent on the faster velocity side of the fault. The patterns of damage from these studies of fault zone head waves and trapped waves are consistent (Ben-Zion and Shi, 2005) with the theoretical prediction that earthquake ruptures on these fault sections have statistically-preferred propagation directions. The early parts of P waveforms are examined for signals that have previously been proposed to scale with the final event magnitude. Data from Turkey and a deep South African gold mine show that scaling is present in signals related to the maximum displacement amplitude and frequency content. The high sampling rate of the instruments in the gold mine enables the reduction of the time window in which measurements are made to below the estimated rupture duration of the largest events. Using increasingly small time windows has only a minimal effect on the scaling of the signals with event magnitude, implying that the size of earthquakes is affected statistically by some property of the early part of the rupture.
Demand Shifting with Thermal Mass in Large Commercial Buildings in a California Hot Climate Zone
Xu, Peng; Yin, Rongxin; Brown, Carrie; Kim, DongEun
The potential for using building thermal mass for load shifting and peak energy demand reduction has been demonstrated in a number of simulation, laboratory, and field studies. Previous Lawrence Berkeley National Laboratory research has demonstrated that the approach is very effective in cool and moderately warm climate conditions (California Climate Zones 2-4). However, this method had not been tested in hotter climate zones. This project studied the potential of pre-cooling the building early in the morning and increasing temperature setpoints during peak hours to reduce cooling-related demand in two typical office buildings in hotter California climates ? one in Visalia (CEC Climate Zone 13) and the other in San Bernardino (CEC Climate Zone 10). The conclusion of the work to date is that pre-cooling in hotter climates has similar potential to that seen previously in cool and moderate climates. All other factors being equal, results to date indicate that pre-cooling increases the depth (kW) and duration (kWh) of the possible demand shed of a given building. The effectiveness of night pre-cooling in typical office building under hot weather conditions is very limited. However, night pre-cooling is helpful for office buildings with an undersized HVAC system. Further work is required to duplicate the tests in other typical buildings and in other hot climate zones and prove that pre-cooling is truly effective.
Large-scale metal zoning in a late-Precambrian skarn-type mineralization, Wadi Kid, SE Sinai, Egypt
NASA Astrophysics Data System (ADS)
Helmy, H. M.; Shalaby, I. M.; Abdel Rahman, H. B.
A Precambrian skarn-type mineralization is recently discovered in the Wadi Kid area in southeast Sinai, Egypt. Two sulfide ore types define large scale metal zoning; Cu-Zn-Co in calc-silicate rocks and Zn-Pb-As-Ag in metapelites. The sulfides and host rocks underwent amphibolite facies metamorphism (2.1-4.2 kbar and 500-620 ¯C). Dating by the chemical Th-U-total Pb isochrone method yields an Th-Pb isochrone age of 660 Ý 25 Ma for metamorphic monazite from metapelites. Overall structural and textural relationships of silicate and sulfide minerals favor syn-tectonic formation during granitoids emplacement in a continental margin setting. Large-scale metal zoning reflects variable distances from the causative pluton(s). The Wadi Kid area is highly prospective for Cu, Zn, Pb and Ag mineralization.
Monitor the Temporal Evolution of Fault Zone with Large Volume Airgun Array
NASA Astrophysics Data System (ADS)
Wang, B.; Yang, W.; Wang, W.; Wang, B.; Wu, G.; Su, Y.; Wang, H.; Wei, B.; Zheng, L.
Monitoring the subsurface change has long been a goal of seismological studies. Great efforts have been made by utilizing natural and artificial repeating seismic sources. To monitor the temporal variations of the crust, we recently established two on-land repeatable seismic sources with large volume airgun arrays. Those sources are located in Binchuan county, Yunnan province and Hutubi county, Xinjiang province, China, respectively. The Binchuan source sits at the center of the West Yunnan Earthquake Prediction Study Area. The Hutubi source is located at the north edge of North Tienshan and around 80 km away from Urumqi. Both locations are important seismic zones with intense strong earthquakes historically. The airgun source generates seismic energy by releasing high pressure air under water and the capacity of the airgun array is indicated by its volume. The volumes of Binchuan and Hutubi sources are 8000 in3 and 12000 in3, respectively, and both are operated with air pressure of 15 MPa. By measuring the ground shaking, those two sources are estimated equivalent to earthquakes with magnitude 0.7 and 0.9, respectively. The seismic signal radiated from the Binchuan source can be registered by seismic station 240 km away from the source, while the Hutubi source can be identified at seismic stations with epicentral distances up to 378 km. Both sources show excellent repeatability indicated by cross-correlations higher than 0.99 for near source seismic recordings. The high repeatability of source favors subsurface monitoring. To calibrate the measuring precision, a continuous experiment was conducted utilizing the Binchuan source form Nov. 2 to Nov. 9, 2012. Seismic velocity variations were measured every one hour for seismic stations with high signal-to-noise ratio (SNR). Clear daily cycles can be observed for most seismic stations with high SNR. Also the Binchuan source was regularly operated once a week during the time period from Nov. 2012 to May 2013. Long term velocity changes were also measured for seismic stations within 100 km from the source. Different patterns were observed for direct and later phases, the results may indicate local velocity changes in the deep part. More comprehensive results may shed some lights on spatial distribution of local anomalies.
DESERT - A multi-scale study of a large active shear zone, the Dead Sea Transform
M. Weber; Z. Ben-Avraham; K. Abu-Ayyash; R. El-Kelani
How do shear zones work and what controls them ? To be able to address this central question of plate tectonics, the DEad SEa Rift Transect (DESERT) group performed an interdisciplinary and multi-scale study of the Dead Sea Rift. DESERT consists of several coincident seismic, magnetotelluric and seismological sub-projects performed by partners from Germany, Israel, Jordan and Palestine. The Dead
Desert - A Multi-scale Study of A Large Active Shear Zone, The Dead Sea Transform
M. Weber; Z. Ben-Avraham; K. Abu-Ayyyash; R. El-Kelani
How do shear zones work and what controls them ? To be able to address this central question of plate tectonics, the DEad SEa Rift Transect (DESERT) group performed an interdisciplinary and multi-scale study of the Dead Sea Rift. DESERT consists of several coincident seismic, magnetotelluric and seismological sub-projects performed by partners from Germany, Israel, Jordan and Palestine. The Dead
Modelling stream flow for use in ecological studies in a large, arid zone river, central Australia
Justin F. Costelloe; Rodger B. Grayson; Thomas A. McMahon
Australian arid zone ephemeral rivers are typically unregulated and maintain a high level of biodiversity and ecological health. Understanding the ecosystem functions of these rivers requires an understanding of their hydrology. These rivers are typified by highly variable hydrological regimes and a paucity, often a complete absence, of hydrological data to describe these flow regimes. A daily time-step, grid-based, conceptual
The Generation of Continents through Subduction Zone Processing of Large Igneous Provinces: A Case Study from the Central American Subduction Zone
NASA Astrophysics Data System (ADS)
Harmon, N.; Rychert, C.
Billions of years ago primary mantle magmas evolved to form the continental crust, although no simple magmatic differentiation process explains the progression to average andesitic crustal compositions observed today. A multiple stage process is often invoked, involving subduction and or oceanic plumes, to explain the strong depletion observed in Archean xenoliths and as well as pervasive tonalite-trondhjemite-granodiorite and komatiite protoliths in the greenstone belts in the crust in the cratons. Studying modern day analogues of oceanic plateaus that are currently interacting with subductions zones can provide insights into continental crust formation. Here we use surface waves to image crustal isotropic and radially anisotropic shear velocity structure above the central American subduction system in Nicaragua and Costa Rica, which juxtaposes thickened ocean island plateau crust in Costa Rica with continental/normal oceanic crust in Nicaragua. We find low velocities beneath the active arc regions (3-6% slower than the surrounding region) and up to 6% radially anisotropic structures within the oceanic crust of the Caribbean Large Igneous Province beneath Costa Rica. The low velocities and radial anisotropy suggest the anomalies are due to pervasive deep crustal magma sills. The inferred sill structures correlate spatially with increased silicic outputs in northern Costa Rica, indicating that deep differentiation of primary magmas is more efficient beneath Costa Rica relative to Nicaragua. Subduction zone alteration of large igneous provinces promotes efficient, deep processing of primary basalts to continental crust. This scenario can explain the formation of continental lithosphere and crust, by both providing strongly depleted mantle lithosphere and a means for rapidly generating a silicic crustal composition.
Regional and Large-Scale Climate Influences on Tree-Ring Reconstructed Null Zone Position in San Francisco Bay
NASA Astrophysics Data System (ADS)
Stahle, D.; Griffin, D.; Cleaveland, M.; Fye, F.; Meko, D.; Cayan, D.; Dettinger, M.; Redmond, K.
A new network of 36 moisture sensitive tree-ring chronologies has been developed in and near the drainage basins of the Sacramento and San Joaquin Rivers. The network is based entirely on blue oak (Quercus douglasii), which is a California endemic found from the lower forest border up into the mixed conifer zone in the Coast Ranges, Sierra Nevada, and Cascades. These blue oak tree-ring chronologies are highly correlated with winter-spring precipitation totals, Sacramento and San Joaquin streamflow, and with seasonal variations in salinity and null zone position in San Francisco Bay. Null zone is the non-tidal bottom water location where density-driven salinity and river-driven freshwater currents balance (zero flow). It is the area of highest turbidity, water residence time, sediment accumulation, and net primary productivity in the estuary. Null zone position is measured by the distance from the Golden Gate of the 2 per mil bottom water isohaline and is primarily controlled by discharge from the Sacramento and San Joaquin Rivers (and ultimately by winter-spring precipitation). The location of the null zone is an estuarine habitat indicator, a policy variable used for ecosystem management, and can have a major impact on biological resources in the San Francisco estuary. Precipitation-sensitive blue oak chronologies can be used to estimate null zone position based on the strong biogeophysical interaction among terrestrial, aquatic, and estuarine ecosystems, orchestrated by precipitation. The null zone reconstruction is 626-years long and provides a unique long term perspective on the interannual to decadal variability of this important estuarine habitat indicator. Consecutive two-year droughts (or longer) allow the null zone to shrink into the confined upper reaches of Suisun Bay, causing a dramatic reduction in phytoplankton production and favoring colonization of the estuary by marine biota. The reconstruction indicates an approximate 10 year recurrence interval between these consecutive two-year droughts and null zone maxima. Composite analyses of the Palmer drought index over North America indicate that the drought and wetness regimes associated with maxima and minima in reconstructed null zone position are largely restricted to the California sector. Composite analyses of the 20th century global sea surface temperature (SST) field indicate that wet years over central California with good oak growth, high flows, and a seaward position for the null zone (minima) are associated with warm El Nino conditions and a "Pineapple Express" SST pattern. The composite SST pattern is not as strong during dry years with poor growth, low flows, and a landward position of the null zone (maxima), but the composite warm SST anomaly in the eastern North Pacific during maxima would be consistent with a persistent ridge and drought over western North America.
Turbocharged engine exhaust gas recirculation system
Stachowicz, R.W.
Improved exhaust gas recirculation systems for turbocharged gas engines that include an exhaust pipe, a turbocharger connected thereto, and a carburetor connected with a source of gas for the engine. The recirculation system includes an air conduit extending from the turbocharger compressor discharge to a venturi, an exhaust gas conduit that extends from a connection with the exhaust pipe between the engine and the turbocharger to the venturi, a second air conduit that extends from the exhaust pipe to a connection with the first air conduit, and control valves located in the exhaust gas conduit and in the second air conduit. The valves are closed when the engine is being started or idling at no load and open when a load is imposed or when engine rpm's are increased. No pumps, blowers, etc. are needed because the system operates on a differential in pressure created within the system to cause the exhaust gas recirculation.
Weak compliance undermines the success of no-take zones in a large government-controlled marine protected area.
Campbell, Stuart J; Hoey, Andrew S; Maynard, Jeffrey; Kartawijaya, Tasrif; Cinner, Joshua; Graham, Nicholas A J; Baird, Andrew H
The effectiveness of marine protected areas depends largely on whether people comply with the rules. We quantified temporal changes in benthic composition, reef fish biomass, and fishing effort among marine park zones (including no-take areas) to assess levels of compliance following the 2005 rezoning of the government-controlled Karimunjawa National Park (KNP), Indonesia. Four years after the rezoning awareness of fishing regulations was high amongst local fishers, ranging from 79.5Ý7.9 (SE) % for spatial restrictions to 97.7Ý1.2% for bans on the use of poisons. Despite this high awareness and strong compliance with gear restrictions, compliance with spatial restrictions was weak. In the four years following the rezoning reef fish biomass declined across all zones within KNP, with >50% reduction within the no-take Core and Protection Zones. These declines were primarily driven by decreases in the biomass of groups targeted by local fishers; planktivores, herbivores, piscivores, and invertivores. These declines in fish biomass were not driven by changes in habitat quality; coral cover increased in all zones, possibly as a result of a shift in fishing gears from those which can damage reefs (i.e., nets) to those which cause little direct damage (i.e., handlines and spears). Direct observations of fishing activities in 2009 revealed there was limited variation in fishing effort between zones in which fishing was allowed or prohibited. The apparent willingness of the KNP communities to comply with gear restrictions, but not spatial restrictions is difficult to explain and highlights the complexities of the social and economic dynamics that influence the ecological success of marine protected areas. Clearly the increased and high awareness of fishery restrictions following the rezoning is a positive step. The challenge now is to understand and foster the conditions that may facilitate compliance with spatial restrictions within KNP and marine parks worldwide. PMID:23226237
Inverse modeling of large-scale spatially distributed vadose zone properties using global optimization
NASA Astrophysics Data System (ADS)
Vrugt, Jasper A.; Schoups, Gerrit; Hopmans, Jan W.; Young, Chuck; Wallender, Wesley W.; Harter, Thomas; Bouten, Willem
Computational capabilities have evolved to a point where it is possible to use multidimensional physically based hydrologic models to study spatial and temporal patterns of water flow in the vadose zone. However, models based on multidimensional governing equations have only received limited attention, in particular because of their computational, distributed input, and parameter estimation requirements. The aim of the present paper is to explore the usefulness and applicability of the inverse method to estimate vadose zone properties using the solution of a physically based, distributed three-dimensional model combined with spatially distributed measured tile drainage data from the 3880-ha Broadview Water District (BWD) in the San Joaquin Valley of California. The inverse problem is posed within a single-criterion Bayesian framework and solved by means of the computerized Shuffled Complex Evolution Metropolis global optimization algorithm. To study the benefits of using a spatially distributed three-dimensional vadose zone model, the results of the 3-D model were compared with those obtained using a simple storage-based bucket model and a spatially averaged one-dimensional unsaturated water flow model for a 2-year period. District-wide results demonstrate that measured spatially distributed patterns of drainage data contain only limited information for the identification of vadose zone model parameters and are particularly inadequate to identify the soil hydraulic properties. In contrast, the drain conductance and a soil matrix bypass coefficient were well determined, indicating that the dominant hydrology of the BWD was determined by drain system properties and preferential flow. Despite the significant CPU time needed for model calibration, results suggest that there are advantages in using physically based hydrologic models to study spatial and temporal patterns of water flow at the scale of a watershed. These models not only generate consistent forecasts of spatially distributed drainage data during the calibration and validation period but also possess unbiased predictive capabilities with respect to measured groundwater table depths not included in the calibration.
Peach bottom recirculation piping replacement ALARA program
Englesson, G.A.; Hilsmeier, A.E.; Mann, B.J.
In late 1983, Philadelphia Electric Company (PECo) began detailed planning to replace the recirculation, residual heat removal, and part of the reactor water cleanup piping of the Peach Bottom Unit 2 reactor. Included in this work was an estimate of the collective exposure expected during piping replacement. That initial estimate, 1945 man-rem, is compared with the actual collective dose incurred during the piping replacement program. Also included are the exposures incurred during two additional tasks (safe end replacement and recirculation pump disassembly and decontamination) not considered in the initial estimate.
Performance of a closed recirculating system with foam separation, nitrification and denitrification units for intensive culture of eel: towards zero emission
Yoshihiro Suzuki; Toshiroh Maruyama; Hiroyuki Numata; Hajime Sato; Makio Asakawa
The development of a closed recirculating aquaculture system that does not discharge effluents would reduce a large amount of pollutant load on aquatic bodies. In this study, eel were reared in a closed recirculating system, which consisted of a rearing tank, a foam separation unit, a nitrification unit and a denitrification unit. The foam separation unit has an inhalation-type aerator
Generation and maintenance of recirculations by Gulf Stream instabilities
Beliakova, Natalia Yurievna, 1967-
This thesis studies the problems of generation and maintenance of recirculations by Gulf Stream instabilities. Observations show that the horizontal structure of the jet and its recirculations suffer significant changes ...
40 CFR 1065.127 - Exhaust gas recirculation.
Code of Federal Regulations, 2010 CFR
...Exhaust gas recirculation. Use the exhaust gas recirculation (EGR) system installed with the engine or one that represents a typical in-use configuration. This includes any applicable EGR cooling...
Procedures requiring extended periods of electrophoresis frequently require recirculation of the get buffer in order to reduce gel artifacts. ere we describe a recirculation device which can be built inexpensively and will fit many different model get boxes....
Separating People and Wildlife: Zoning as a Conservation Strategy for Large Carnivores
Courtney L. Larson
Large carnivores are some of the worlds most difficult species to conserve because of their large spatial requirements, low population density, and high potential for conflict with humans. However, large carnivores are valuable for ecological, cultural, and ethical reasons. Carnivore management can take a wide variety of forms, including translocation, sterilization, livestock compensation programs, regulated hunting, improved livestock husbandry practices,
Interface shape, heat transfer and fluid flow in the floating zone growth of large silicon crystals with the needle-eye technique
Alfred M■hlbauer; Andris Muiznieks; Janis Virbulis; Anke L■dge; Helge Riemann
A computer simulation is carried out to study the interface shape, heat transfer and fluid flow in the floating zone (FZ) growth of large (> 100 mm) Si crystals with the needle-eye technique and with feed\\/crystal rotation. Natural convection, thermocapillary convection, electromagnetic (EM) forces and rotation in the melt are considered. The unknown shape of the molten zone is calculated
Structure of the Lesser Antilles subduction zone backstop and its role in a large accretionary system
NASA Astrophysics Data System (ADS)
Bangs, Nathan L.; Christeson, Gail L.; Shipley, Thomas H.
The role of a backstop in subduction zones has been the subject of numerous laboratory and numerical modeling studies; however, few field observations exist revealing how backstops control deformation in subduction zones and accretionary wedge construction. A seismic reflection and refraction survey acquired in 1998 with the R/V Maurice Ewing reveals the geometry of the forearc igneous crust, accretionary wedge, and forearc basin structure of the northern Guadeloupe area of the Lesser Antilles forearc. An accreted block of buoyant crust, accreted in the late Miocene, forms the toe of the overriding arc crust and forms the backstop. We imaged the top of this surface, beneath the forearc basin, to its seaward edge where it meets the subducting oceanic crust. The toe of the backstop was thrust upward and forms a steep buttress in contact with the lower half of the accretionary wedge. The steep buttress produces a narrow inner deformation zone with minimal backthrusting of the accretionary complex landward over the backstop, and a narrow <10 km transition between accreted and forearc basin sediment. Seismic reflections from the subducting crust and the decollement appear beneath the entire accretionary wedge and below the backstop toe. Separating the decollement and the subducting crust is an interval, usually between 500 and 750 m, of underthrust sediment carried underneath the accretionary wedge and subducted 15 km landward and beneath the toe of the backstop. We speculate that the upturned geometry of the toe of the backstop and a weak fluid-rich decollement may facilitate sediment subduction beneath the backstop and potentially into the mantle.
Particle sieve analysis for determining solids removal efficiency of water treatment components in a recirculating aquaculture system
Timothy J. Pfeiffer; Andrew Osborn; Megan Davis
Recirculating aquaculture systems offer potential finfish production units for small-scale entities as well as large-scale operations. However, the water treatment components of such systems require efficient and proper operation to assure successful production. This study evaluated the solids removal ability of three water treatment components in a two-tank recirculating aquaculture system (28m3) utilized for the warmwater production of tilapia. The
The influence of productivity and width of littoral zone on the trophic position of a large-bodied omnivore.
Stenroth, Patrik; Holmqvist, Niklas; Nystr—m, Per; Berglund, Olof; Larsson, Per; GranÕli, Wilhelm
Omnivory is common in many food webs. Omnivores in different habitats can potentially change their feeding behaviour and alter their trophic position and role according to habitat conditions. Here we examine the trophic level and diet of the omnivorous signal crayfish (Pacifastacus leniusculus) in gradients of trophic status and lake size, both of which have been previously suggested to affect trophic position of predators separately or combined as productive space. We found the trophic position of omnivorous crayfish to be positively correlated with lake trophic status, but found no evidence for any influence of lake size or productive space on crayfish trophic position. The higher trophic position of crayfish in eutrophic lakes was largely caused by a shift in crayfish diet and not by an increase in trophic links in basal parts of the food web. Hence, our results support the "productivity hypothesis," suggesting that food chains can be longer in more productive systems. Furthermore, stable isotope data indicated that larger crayfish are more predatory than smaller crayfish in lakes with wider littoral zones. Wider littoral zones promoted the development of intrapopulation differences in trophic position whereas narrow littoral zones did not. Hence, differences in habitat quality between and within lakes seem to influence the trophic positions of omnivorous crayfish. PMID:18368427
A model for large-scale plastic yield of the Gorda deformation zone
Denlinger, R.P. (Hawaii Volcano Observatory, Hawaii Volcanoes National Park (United States))
A solution satisfying both continuity and force balance for an elastoplastic Gorda plate in planar coordinates is presented. Continuity on a plane is used to approximate continuity on a spherical surface due to the small area under consideration. The zone of plastic yield vs the seismicity does not change much with fault strength along the Mendocino. Due to the nature of the deformation, the direction of maximum shear stress near the Mendocino triple junction is between 40 and 50 deg to the Mendocino transform in both cases, but curves sharply in the neighborhood of the transform if the fault is strong. It is concluded that the strength of the Mendocino relative to the lithosphere varied over time. Five million years ago a change in pole position increased convergence of the Blanco fracture zone and Mendocino transform, exponentially increasing brittle shear stresses across the fault. Between 2.47 Ma and 1.8 Ma the convergence stabilized, and the resistance to sliding along the transform decayed back to residual levels. The relative slip along the fault during this time was about 1 km. As a result of this history, previous models either for flexural-slip or for right-lateral shear will fit the deformation at different times. 35 refs.
Evidence for large prehistoric earthquakes in the northern New Madrid Seismic Zone, central United States
Li, Y.; Schweig, E.S.; Tuttle, M.P.; Ellis, M.A.
We surveyed the area north of New Madris, Missouri, for prehistoric liquefaction deposits and uncovered two new sites with evidence of pre-1811 earthquakes. At one site, located about 20 km northeast of New Madrid, Missouri, radiocarbon dating indicates that an upper sand blow was probably deposited after A.D. 1510 and a lower sand blow was deposited prior to A.D. 1040. A sand blow at another site about 45 km northeast of New Madrid, Missouri, is dated as likely being deposited between A.D.55 and A.D. 1620 and represents the northernmost recognized expression of prehistoric liquefaction likely related to the New Madrid seismic zone. This study, taken together with other data, supports the occurrence of at least two earthquakes strong enough to indcue liquefaction or faulting before A.D. 1811, and after A.D. 400. One earthquake probably occurred around AD 900 and a second earthquake occurred around A.D. 1350. The data are not yet sufficient to estimate the magnitudes of the causative earthquakes for these liquefaction deposits although we conclude that all of the earthquakes are at least moment magnitude M ~6.8, the size of the 1895 Charleston, Missouri, earthquake. A more rigorous estimate of the number and sizes of prehistoric earthquakes in the New Madrid sesmic zone awaits evaluation of additional sites.
Recirculation as a Form of Conservation.
ERIC Educational Resources Information Center
Gordon, Jeffrey J.
Discusses nine forms of conservation practices: sustained yield, repair, careful use, greater efficiency, lower consumption, doing without, substitution, new resources, and recycling. Suggests recirculation (saving goods from discard and from being broken down in a new manufacturing stage) as a 10th form of conservation practice. (Author/JN)
Recirculating natural convection solar energy collector
Soleau; B. S. Jr
Recirculating natural convection solar energy collectors are disclosed. In one species of the invention, the collector comprises an insulated housing, a cover of glass or other suitable transparent material, a transparent plate of glass or other suitable material mounted inside said housing and spaced apart from the cover, a heat absorber mounted inside the housing and spaced apart from the
Large-scale high-resolution seismic study in the western end of the Nankai seismogenic zone
NASA Astrophysics Data System (ADS)
Nakanishi, A.; Kodaira, S.; Fujie, G.; Obana, K.; Takizawa, K.; Kashiwase, K.; Kaneda, Y.
In the Nankai Trough subduction seismogenic zone, M8-class great earthquake area can be divided into three segments; they are source regions of the Nankai, Tonankai and presumed Tokai earthquakes. The Nankai and Tonankai earthquakes had often occurred simultaneously, and caused a great event. Possibility of a megathrust earthquake along the Nankai Trough from Tokai to the Hyuga-nada, east off the Kyushu Island, Japan, is recently pointed out. To understand rupture synchronization and segmentation of the Nankai megathrust earthquake, it is important to know the deep seismic image and activity in the Hyuga-nada, the western end of the Nankai seismogenic zone. To obtain the deep structure related to the rupture synchronization and segmentation in this region, the large-scale high-resolution wide-angle seismic study was conducted in Dec. 2008. In this study, 160 ocean bottom seismographs are deployed with a spacing of 5km along four seismic profiles, 830km in a total length. A tuned airgun system (7800 cu. in.) was shot every 200m along these profiles (Fig. 1). This research is part of Research concerning Interaction Between the Tokai, Tonankai and Nankai Earthquakes funded by Ministry of Education, Culture, Sports, Science and Technology, Japan. The subducting plate interface beneath coseismic slip zone of the 1968 event (Mw7.5) is the top of the oceanic crust contacting with the old accreted sediments. The young accretionary sediments (Vp<5km/s) above the subducting Philippine Sea plate reaches a maximum thickness of ~10km, and is widely distributed landward. In the northwestern half of the slip zone of the 1968 event, the young Accretionary sediments become thin abruptly. Figure 1: Location map of seismic survey
Relaxation/sparse matrix solvers for three-dimensional recirculating flows
NASA Astrophysics Data System (ADS)
Himansu, A.; Khosla, P. K.; Rubin, S. G.
Numerical techniques for recirculating-flow problems are developed and demonstrated. The flux-split global relaxation procedure developed by Cohen and Khosla (1988) is used to solve the reduced nondimensional Navier-Stokes equations for steady three-dimensional reversing compressible flows in trough, wing, and boat-tail geometries. The governing equations, discretization, and solution procedure (involving the use of a direct sparse-matrix solver for the cross-plane matrix inversion) are discussed in detail, and the results are presented graphically. Laminar-flow solutions with large three-dimensional recirculation bubbles are obtained for all three geometries.
Large eddy simulation of soot evolution in an aircraft combustor
NASA Astrophysics Data System (ADS)
Mueller, Michael E.; Pitsch, Heinz
An integrated kinetics-based Large Eddy Simulation (LES) approach for soot evolution in turbulent reacting flows is applied to the simulation of a Pratt & Whitney aircraft gas turbine combustor, and the results are analyzed to provide insights into the complex interactions of the hydrodynamics, mixing, chemistry, and soot. The integrated approach includes detailed models for soot, combustion, and the unresolved interactions between soot, chemistry, and turbulence. The soot model is based on the Hybrid Method of Moments and detailed descriptions of soot aggregates and the various physical and chemical processes governing their evolution. The detailed kinetics of jet fuel oxidation and soot precursor formation is described with the Radiation Flamelet/Progress Variable model, which has been modified to account for the removal of soot precursors from the gas-phase. The unclosed filtered quantities in the soot and combustion models, such as source terms, are closed with a novel presumed subfilter PDF approach that accounts for the high subfilter spatial intermittency of soot. For the combustor simulation, the integrated approach is combined with a Lagrangian parcel method for the liquid spray and state-of-the-art unstructured LES technology for complex geometries. Two overall fuel-to-air ratios are simulated to evaluate the ability of the model to make not only absolute predictions but also quantitative predictions of trends. The Pratt & Whitney combustor is a Rich-Quench-Lean combustor in which combustion first occurs in a fuel-rich primary zone characterized by a large recirculation zone. Dilution air is then added downstream of the recirculation zone, and combustion continues in a fuel-lean secondary zone. The simulations show that large quantities of soot are formed in the fuel-rich recirculation zone, and, furthermore, the overall fuel-to-air ratio dictates both the dominant soot growth process and the location of maximum soot volume fraction. At the higher fuel-to-air ratio, the maximum soot volume fraction is found inside the recirculation zone; at the lower fuel-to-air ratio, turbulent fluctuations in the mixture fraction promote the oxidation of soot inside the recirculation zone and suppress the accumulation of a large soot volume fraction. Downstream, soot exits the combustor in intermittent fuel-rich pockets that are not mixed during the injection of dilution air and subsequent secondary fuel-lean combustion. At the higher fuel-to-air ratio, the frequency of these fuel-rich pockets is increased, leading to higher soot emissions from the combustor. Quantitatively, the soot emissions from the combustor are overpredicted by about 50%, which is a substantial improvement over previous works utilizing RANS to predict such emissions. In addition, the ratio between the two fuel-to-air ratios predicted by LES compares very favorably with the experimental measurements. Furthermore, soot growth is dominated by an acetylene-based pathway rather than an aromatic-based pathway, which is usually the dominant mechanism in nonpremixed flames. This finding is the result of the interactions between the hydrodynamics, mixing, chemistry, and soot in the recirculation zone and the resulting residence times of soot at various mixture fractions (compositions), which are not the same in this complex recirculating flow as in nonpremixed jet flames.
Stress evolution following the 18111812 large earthquakes in the New Madrid Seismic Zone
Liu, Mian
, in the NMSZ comparable to the large 1811Ù1812 earthquakes [Tuttle and Schweig, 1995; Tuttle et al., 2002 two thousand years [Tuttle et al., 2002]. However, the GPS data show insignificant strain rates around
A River's Liver Microbial Processes within the Hyporheic Zone of a Large Lowland River
Helmut Fischer; Frank Kloep; Sabine Wilzcek; Martin T Pusch
Little is known on microbial activities in the sediments of large lowland rivers despite of their potentially high influence\\u000a on biogeochemical budgets. Based on field measurements in a variety of sedimentary habitats typical for a large lowland river\\u000a (Elbe, Germany), we present results on the abundance and production of sedimentary bacteria, the potential activity of a set\\u000a of extracellular enzymes,
Experimental characterization of the initial zone of an annular jet with a very large diameter ratio
NASA Astrophysics Data System (ADS)
Danlos, AmÕlie; Lalizel, Gildas; Patte-Rouland, BÕatrice
This article presents an experimental investigation of a large diameter ratio annular air jet by particle image velocimetry, Laser Doppler Anemometry, hot-wire anemometry and time-resolved tomography. Annular jets consist of a round nozzle with an obstacle placed in its center. These jets are thus defined by an external and an internal diameter corresponding to the round nozzle lips and the diameter of the obstacle, respectively. The ratio between these two diameters defines the behavior of the flow across a characteristic diameter called diameter ratio. In most industrial applications these jets have large diameter ratios, superior to 0.7.
Possible Morphologic Indicators for the Location of Large Slow Earthquakes in Subduction Zones
W. R. McCann
Global observations of convergent margin morphology may identify regions more likely to produce tsunami earthquakes. Earthquake observations and laboratory modeling show that subduction of seafloor relief influences the accretionary prism (AP), interplate coupling and the occurrence of large interplate earthquakes. The amplitude, wavelength, and direction of convergence of seafloor roughness appear to relate to the scale of the disruption of
Inverse modeling of large-scale spatially distributed vadose zone properties using global optimization
Vrugt, Jasper A.
, this is time consuming and requires a large amount of computer storage when applied to a small dimension numerically from the Fourier transform of the wake potential which is obtained from the computer code MAFIA-T3 an analytical method for the hole-coupling problem valid for a wide range of frequencies. iii #12;Contents 1
Large multicellular filamentous bacteria under the oxygen minimum zone of the eastern South Pacific: a forgotten biosphere
NASA Astrophysics Data System (ADS)
Gallardo, Victor Ariel; Espinoza, Carola
In the soft reduced sediments of the continental shelf, below the oxygen minimum zone (OMZ) of the eastern South Pacific (ESP), peculiar microbial communities have been disclosed which include a variety of large prokaryotes, protists and small metazoans. Dominant among the prokaryotes are large multi-cellular filamentous bacteria which, according to their size range, are roughly divided into megabacteria and macrobacteria. The former group is made up of a few species of Gamma Proteobacteria of the genera Thioploca and Beggiatoa and the second group includes a diversity of phenotypes. Protists include ciliates, flagellates, and foraminifers and the metazoans are mostly nematodes and small polychaetes. A significant similarity has been found in the exploitation of the area/volume relationship among these large bacteria and their fossil analog forms as described from pre-Cambrian rocks. For the same reason, the latter have mostly been referred to as algae or cyanobacteria in the literature. The presence of these seemingly ancient bacteria in the sediments of the oxygen minimum zones of the ESP, one of the most productive but also ecologically most inefficient marine ecosystems of the world, suggests that such setting must have prevailed throughout the geological history of the planet allowing for their survival and further that it might be considered an analog of Proterozoic ocean conditions. These non-cyanobacterial communities offer an alternative hypothesis to students of the evolution of life on Earth and may be of special interest to astrobiologists looking for life or traces of life in terrestrial or extraterrestrial environments since these do not necessarily imply a photosynthesis-based metabolism.
Methylation profiling of mediastinal gray zone lymphoma reveals a distinctive signature with elements shared by classical Hodgkins lymphoma and primary mediastinal large B-cell lymphoma
Eberle, Franziska C.; Rodriguez-Canales, Jaime; Wei, Lai; Hanson, Jeffrey C.; Killian, J. Keith; Sun, Hong-Wei; Adams, Lisa G.; Hewitt, Stephen M.; Wilson, Wyndham H.; Pittaluga, Stefania; Meltzer, Paul S.; Staudt, Louis M.; Emmert-Buck, Michael R.; Jaffe, Elaine S.
Background Mediastinal gray zone lymphoma is a newly recognized entity with transitional morphological and immunophenotypic features between the nodular sclerosis subtype of Hodgkins lymphoma and primary mediastinal large B-cell lymphoma. Diagnostic criteria for mediastinal gray zone lymphoma are still challenging, and the optimal therapy is as yet undetermined. Epigenetic changes have been implicated in the loss of the B-cell program in classical Hodgkins lymphoma, and might provide a basis for the immunophenotypic alterations seen in mediastinal gray zone lymphoma. Design and Methods We performed a large-scale DNA methylation analysis of microdissected tumor cells to investigate the biological underpinnings of mediastinal gray zone lymphoma and its association with the related entities classical Hodgkins lymphoma and primary mediastinal large B-cell lymphoma, making comparisons with the presumptively less related diffuse large B-cell lymphoma. Results Principal component analysis demonstrated that mediastinal gray zone lymphoma has a distinct epigenetic profile intermediate between classical Hodgkins lymphoma and primary mediastinal large B-cell lymphoma but remarkably different from that of diffuse large B-cell lymphoma. Analysis of common hypo- and hypermethylated CpG targets in mediastinal gray zone lymphoma, classical Hodgkins lymphoma, primary mediastinal large B-cell lymphoma and diffuse large B-cell lymphoma was performed and confirmed the findings of the principal component analysis. Based on the epigenetic profiles we were able to establish class prediction models utilizing genes such as HOXA5, MMP9, EPHA7 and DAPK1 which could distinguish between mediastinal gray zone lymphoma, classical Hodgkins lymphoma and primary mediastinal large B-cell lymphoma with a final combined prediction of 100%. Conclusions Our data confirm a close relationship between mediastinal gray zone lymphoma and both classical Hodgkins lymphoma and primary mediastinal large B-cell lymphoma. However, important differences were observed as well, allowing a clear distinction from both parent entities. Thus, mediastinal gray zone lymphoma cannot be assigned to either classical Hodgkins lymphoma or primary mediastinal large B-cell lymphoma, validating the decision to create an intermediate category in the World Health Organization classification. PMID:21454882
High Power Picosecond Laser Pulse Recirculation
Shverdin, M Y; Jovanovic, I; Semenov, V A; Betts, S M; Brown, C; Gibson, D J; Shuttlesworth, R M; Hartemann, F V; Siders, C W; Barty, C P
We demonstrate a nonlinear crystal-based short pulse recirculation cavity for trapping the second harmonic of an incident high power laser pulse. This scheme aims to increase the efficiency and flux of Compton-scattering based light sources. We demonstrate up to 36x average power enhancement of frequency doubled sub-millijoule picosecond pulses, and 17x average power enhancement of 177 mJ, 10 ps, 10 Hz pulses.
The large normal-faulting Mariana earthquake of April 5, 1990 in uncoupled subduction zone
Yasuhiro Yoshida; Katsuyuki Abe; Kenji Satake
A large, Ms=7.5, shallow earthquake occurred beneath the Mariana trench on April 5, 1990. From the relocated aftershock distribution, the fault area is estimated to be 70æ40 km2. A tsunami observed on the Japanese islands verifies that the depth of the main shock is shallow. For waveform analysis, we use long-period surface waves and body waves recorded at global networks
Fuel cell cooling and recirculation system
Dighe, S.V.
Method and apparatus for cooling and recirculating oxidant to the cathode of a fuel cell stack. Heat energy is removed from the fuel cell stack through utilization of excess air or other oxidant relative to the stoichiometric amount for reaction with a hydrogen-containing fuel. Reaction products, including excess air and water, flow to a nozzle upstream of a flow constricting venturi. A coolant, such as liquid water in a fine spray form, is injected through the venturi and draws the reaction products through the venturi. The mixing of the coolant and the reaction products results in a condensation of the high temperature reaction product water vapor and further dehumidification of the reaction products takes place in a passive separator such as a demister. Coolant is injected into the venturi in sufficient quantity to develop the pressure head necessary to recirculate the cooled and dehumidified air through a conduit system and back to the fuel cell stack. A supply of makeup air is also provided. Coolant and water collected in the passive separator can also be recirculated for injection through the venturi.
Fabrication and evaluation of a weak zone plate for monitoring performance of large orbiting telescopes
NASA Technical Reports Server (NTRS)
Erickson, K. E.
An experimental study of the feasibility of monitoring the optical performance of a large telescope by means of a very faint phase hologram imprinted upon the primary mirror is reported. Tests have been made using an f/5 telescope with a 0.3 m aperture. The results indicate that a usable hologram can be so faint and so restricted in area that it will probably not interfere significantly with normal operation of a 3.0 m telescope at wavelengths longer than 100 nm for stars brighter than magnitude 29.
Structure of the Koyna-Warna Seismic Zone, Maharashtra, India: A possible model for large induced earthquakes elsewhere
NASA Astrophysics Data System (ADS)
Catchings, R. D.; Dixit, M. M.; Goldman, M. R.; Kumar, S.
The Koyna-Warna area of India is one of the best worldwide examples of reservoir-induced seismicity, with the distinction of having generated the largest known induced earthquake (M6.3 on 10 December 1967) and persistent moderate-magnitude (>M5) events for nearly 50 years. Yet, the fault structure and tectonic setting that has accommodated the induced seismicity is poorly known, in part because the seismic events occur beneath a thick sequence of basalt layers. On the basis of the alignment of earthquake epicenters over an ~50 year period, lateral variations in focal mechanisms, upper-crustal tomographic velocity images, geophysical data (aeromagnetic, gravity, and magnetotelluric), geomorphic data, and correlation with similar structures elsewhere, we suggest that the Koyna-Warna area lies within a right step between northwest trending, right-lateral faults. The sub-basalt basement may form a local structural depression (pull-apart basin) caused by extension within the step-over zone between the right-lateral faults. Our postulated model accounts for the observed pattern of normal faulting in a region that is dominated by north-south directed compression. The right-lateral faults extend well beyond the immediate Koyna-Warna area, possibly suggesting a more extensive zone of seismic hazards for the central India area. Induced seismic events have been observed many places worldwide, but relatively large-magnitude induced events are less common because critically stressed, preexisting structures are a necessary component. We suggest that releasing bends and fault step-overs like those we postulate for the Koyna-Warna area may serve as an ideal tectonic environment for generating moderate- to large- magnitude induced (reservoir, injection, etc.) earthquakes.
Method and apparatus for advanced staged combustion utilizing forced internal recirculation
Rabovitser, Iosif K.; Knight, Richard A.; Cygan, David F.; Nester, Serguei; Abbasi, Hamid A.
A method and apparatus for combustion of a fuel in which a first-stage fuel and a first-stage oxidant are introduced into a combustion chamber and ignited, forming a primary combustion zone. At least about 5% of the total heat output produced by combustion of the first-stage fuel and the first-stage oxidant is removed from the primary combustion zone, forming cooled first-stage combustion products. A portion of the cooled first-stage combustion products from a downstream region of the primary combustion zone is recirculated to an upstream region of primary combustion zone. A second-stage fuel is introduced into the combustion chamber downstream of the primary combustion zone and ignited, forming a secondary combustion zone. At least about 5% of the heat from the secondary combustion zone is removed. In accordance with one embodiment, a third-stage oxidant is introduced into the combustion chamber downstream of the secondary combustion zone, forming a tertiary combustion zone.
Global Omori law decay of triggered earthquakes: Large aftershocks outside the classical aftershock zone
Parsons, T.
Triggered earthquakes can be large, damaging, and lethal as evidenced by the 1999 shocks in Turkey and the 2001 earthquakes in El Salvador. In this study, earthquakes with Ms ??? 7.0 from the Harvard centroid moment tensor (CMT) catalog are modeled as dislocations to calculate shear stress changes on subsequent earthquake rupture planes near enough to be affected. About 61% of earthquakes that occured near (defined as having shear stress change ???????? ??? 0.01 MPa) the Ms ??? 7.0 shocks are associated with calculated shear stress increases, while ???39% are associated with shear stress decreases. If earthquakes associated with calculated shear stress increases are interpreted as triggered, then such events make up at least 8% of the CMT catalog. Globally, these triggered earthquakes obey an Omori law rate decay that lasts between ???7-11 years after the main shock. Earthquakes associated with calculated shear stress increases occur at higher rates than background up to 240 km away from the main shock centroid. Omori's law is one of the few time-predictable patterns evident in the global occurrence of earthquakes. If large triggered earthquakes habitually obey Omori's law, then their hazard can be more readily assessed. The characteristics rate change with time and spatial distribution can be used to rapidly assess the likelihood of triggered earthquakes following events of Ms ??? 7.0. I show an example application to the M = 7.7 13 January 2001 El Salvador earthquake where use of global statistics appears to provide a better rapid hazard estimate than Coulomb stress change calculations.
Global Omori law decay of triggered earthquakes: large aftershocks outside the classical aftershock zone
Parsons, Tom
Triggered earthquakes can be large, damaging, and lethal as evidenced by the 1999 shocks in Turkey and the 2001 earthquakes in El Salvador. In this study, earthquakes with Ms ? 7.0 from the Harvard centroid moment tensor (CMT) catalog are modeled as dislocations to calculate shear stress changes on subsequent earthquake rupture planes near enough to be affected. About 61% of earthquakes that occurred near (defined as having shear stress change ???? ? 0.01 MPa) the Ms ? 7.0 shocks are associated with calculated shear stress increases, while ?39% are associated with shear stress decreases. If earthquakes associated with calculated shear stress increases are interpreted as triggered, then such events make up at least 8% of the CMT catalog. Globally, these triggered earthquakes obey an Omori law rate decay that lasts between ?711 years after the main shock. Earthquakes associated with calculated shear stress increases occur at higher rates than background up to 240 km away from the main shock centroid. Omori's law is one of the few time-predictable patterns evident in the global occurrence of earthquakes. If large triggered earthquakes habitually obey Omori's law, then their hazard can be more readily assessed. The characteristic rate change with time and spatial distribution can be used to rapidly assess the likelihood of triggered earthquakes following events of Ms ? 7.0. I show an example application to the M = 7.7 13 January 2001 El Salvador earthquake where use of global statistics appears to provide a better rapid hazard estimate than Coulomb stress change calculations.
Global Omori law decay of triggered earthquakes: Large aftershocks outside the classical aftershock zone
NASA Astrophysics Data System (ADS)
Parsons, Tom
Triggered earthquakes can be large, damaging, and lethal as evidenced by the1999 shocks in Turkey and the 2001 earthquakes in El Salvador. In this study, earthquakes with Ms ? 7.0 from the Harvard centroid moment tensor (CMT) catalog are modeled as dislocations to calculate shear stress changes on subsequent earthquake rupture planes near enough to be affected. About 61% of earthquakes that occurred near (defined as having shear stress change ???? ? 0.01 MPa) the Ms ? 7.0 shocks are associated with calculated shear stress increases, while 39% are associated with shear stress decreases. If earthquakes associated with calculated shear stress increases are interpreted as triggered, then such events make up at least 8% of the CMT catalog. Globally, these triggered earthquakes obey an Omori law rate decay that lasts between 7-11 years after the main shock. Earthquakes associated with calculated shear stress increases occur at higher rates than background up to 240 km away from the main shock centroid. Omori's law is one of the few time-predictable patterns evident in the global occurrence of earthquakes. If large triggered earthquakes habitually obey Omori's law, then their hazard can be more readily assessed. The characteristic rate change with time and spatial distribution can be used to rapidly assess the likelihood of triggered earthquakes following events of Ms ? 7.0. I show an example application to the M = 7.7 13 January 2001 El Salvador earthquake where use of global statistics appears to provide a better rapid hazard estimate than Coulomb stress change calculations.
Exhaust gas recirculation system for an internal combustion engine
Wu, Ko-Jen
An exhaust gas recirculation system for an internal combustion engine comprises an exhaust driven turbocharger having a low pressure turbine outlet in fluid communication with an exhaust gas conduit. The turbocharger also includes a low pressure compressor intake and a high pressure compressor outlet in communication with an intake air conduit. An exhaust gas recirculation conduit fluidly communicates with the exhaust gas conduit to divert a portion of exhaust gas to a low pressure exhaust gas recirculation branch extending between the exhaust gas recirculation conduit and an engine intake system for delivery of exhaust gas thereto. A high pressure exhaust gas recirculation branch extends between the exhaust gas recirculation conduit and the compressor intake and delivers exhaust gas to the compressor for mixing with a compressed intake charge for delivery to the intake system.
Phosphorus removal in a marine prototype, recirculating aquaculture system
Yoram Barak; Eddie Cytryn; Iliya Gelfand; Michael Krom; Jaap van Rijn
Phosphorus dynamics were examined in a prototype, zero-discharge, marine-recirculating system. Operation of the system without discharge of water and sludge was enabled by recirculation of effluent water through two separate treatment loops. Surface water from the fish basin was pumped over a trickling filter in one loop, while bottom-water was recirculated through a sedimentation basin followed by a fluidized bed
Monitoring of Leachate Recirculation in a Bioreactor Using Electrical Resistivity
S. Grellier; N. Bureau; H. Robain; A. Tabbagh; C. Camerlynck; R. Guerin
The bioreactor is a concept of waste landfill management consisting in speeding up the biodegradation by optimizing the moisture content through leachate recirculation. Electrical resistivity tomography (ERT) is carried out with fast resistivity-meter (Syscal Pro, IRIS Instruments, developed in the framework of the research project CERBERE 01V0665-69, funded by the French Research Ministry) to monitor leachate recirculation. During a recirculation
Development of large-field high-resolution hard x-ray imaging microscopy and microtomography with Fresnel zone plate objective
NASA Astrophysics Data System (ADS)
Suzuki, Yoshio; Takeuchi, Akihisa; Terada, Yasuko; Uesugi, Kentaro; Tamura, Shigeharu
A hard x-ray imaging microscope system of high spatial resolution and large field of view (FOV) has been developed at the beamline 37 XU of SPring-8. By utilizing the 30 m-long experimental station, large magnification can be attained with a large diameter Fresnel zone plate (FZP) objective. Some configurations of microscope systems were tested. In a typical condition, a magnification of 133 and a FOV of 123 ?m are attained using a FZP with a diameter of 310 ?m and an outermost zone width of 100 nm, and the spatial resolution evaluated by observing resolution test chart is 160 nm in full pitch of periodic object with an exposure time of 1 s. When a FZP with an outermost zone width of 50 nm is used, a spatial resolution better than 100 nm is achieved. Phase-contrast imaging by Zernike's method was also tested, and three dimensional measurement by computer tomography (CT) method was also carried out.
Estuarine habitat quality reflects urbanization at large spatial scales in South Carolina's coastal zone.
Van Dolah, Robert F; Riekerk, George H M; Bergquist, Derk C; Felber, Jordan; Chestnut, David E; Holland, A Fredrick
Land cover patterns were evaluated in 29 estuarine watersheds of South Carolina to determine relationships between urban/suburban development and estuarine habitat quality. Principal components analysis and Pearson product moment correlation analyses were used to examine the relationships between ten land cover categories and selected measures of nutrient or bacterial enrichment in the water column and contaminant enrichment in sediments. These analyses indicated strong relationships between land cover categories representing upland development and a composite measure of 24 inorganic and organic contaminants using the Effect Range Median-Quotient (ERM-Q). Similar relationships also were observed for the summed concentrations of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), pesticides, and metals. Data obtained from tidal creeks generally showed stronger correlations between urban/suburban land use and pesticides and metals compared to data obtained from larger open water habitats. Correlations between PAH concentrations and the urban/suburban land cover categories were similar between creek and open water habitats. PCB concentrations generally showed very little relationship to any of the land cover categories. Measures of nutrient enrichment, which included total Kjeldahl nitrogen (TKN), nitrate-nitrite, phosphorus, chlorophyll-a, and total organic carbon, were generally not significantly correlated with any land cover categories, whereas fecal coliform bacteria were significantly and positively correlated with the urban/suburban land cover categories and negatively correlated with the non-urban land cover categories. Fecal coliform correlations were stronger using data from the open water sites than from the tidal creek sites. Both ERM-Q and fecal coliform concentrations were much greater and more pervasive in watersheds with relatively high (>50%) urban/suburban cover compared to watersheds with low (<30%) urban/suburban cover. These analyses support the hypotheses that estuarine habitat quality reflects upland development patterns at large spatial scales, and that upland urbanization can result in increased risk of biological degradation and reduced safe human use of South Carolina's coastal resources. PMID:17997472
Estimation of Recurrence Interval of Large Earthquakes on the Central Longmen Shan Fault Zone Based on Seismic Moment Accumulation/Release Model
Zhang, Shimin
Recurrence interval of large earthquake on an active fault zone is an important parameter in assessing seismic hazard. The 2008 Wenchuan earthquake (Mw 7.9) occurred on the central Longmen Shan fault zone and ruptured the Yingxiu-Beichuan fault (YBF) and the Guanxian-Jiangyou fault (GJF). However, there is a considerable discrepancy among recurrence intervals of large earthquake in preseismic and postseismic estimates based on slip rate and paleoseismologic results. Post-seismic trenches showed that the central Longmen Shan fault zone probably undertakes an event similar to the 2008 quake, suggesting a characteristic earthquake model. In this paper, we use the published seismogenic model of the 2008 earthquake based on Global Positioning System (GPS) and Interferometric Synthetic Aperture Radar (InSAR) data and construct a characteristic seismic moment accumulation/release model to estimate recurrence interval of large earthquakes on the central Longmen Shan fault zone. Our results show that the seismogenic zone accommodates a moment rate of (2.7?Ý?0.3)?æ?1017?N?m/yr, and a recurrence interval of 3900?Ý?400?yrs is necessary for accumulation of strain energy equivalent to the 2008 earthquake. This study provides a preferred interval estimation of large earthquakes for seismic hazard analysis in the Longmen Shan region. PMID:23878524
Exhaust gas recirculation in a homogeneous charge compression ignition engine
Duffy, Kevin P. (Metamora, IL); Kieser, Andrew J. (Morton, IL); Rodman, Anthony (Chillicothe, IL); Liechty, Michael P. (Chillicothe, IL); Hergart, Carl-Anders (Peoria, IL); Hardy, William L. (Peoria, IL)
A homogeneous charge compression ignition engine operates by injecting liquid fuel directly in a combustion chamber, and mixing the fuel with recirculated exhaust and fresh air through an auto ignition condition of the fuel. The engine includes at least one turbocharger for extracting energy from the engine exhaust and using that energy to boost intake pressure of recirculated exhaust gas and fresh air. Elevated proportions of exhaust gas recirculated to the engine are attained by throttling the fresh air inlet supply. These elevated exhaust gas recirculation rates allow the HCCI engine to be operated at higher speeds and loads rendering the HCCI engine a more viable alternative to a conventional diesel engine.
BWR recirculation pump isolation valve disk stellite repair
Alexakos, N.P.
A major repair program was developed for the unit 2 recirculation pump isolation valves at the Peach Bottom atomic power station after an initial inspection revealed disk seat cracking. The access for inspection of these valves was made possible due to the recirculation system piping replacement during the sixth refueling outage. This was the first opportunity to disassemble the valves completely for inspection since the construction phase. These valves are the only blocking point between the reactor and the recirculation pumps. Preparation for the disassembly and inspection was planned prior to the recirculation piping replacement. A description of the maintenance procedure, problem areas, and results are presented.
3D Modeling of Strong Ground Motion in the Pacific Northwest From Large Earthquakes in the Cascadia Subduction Zone
NASA Astrophysics Data System (ADS)
Olsen, K. B.; Geisselmeyer, A.; Stephenson, W. J.; Mai, P. M.
The Cascadia subduction zone in the Pacific Northwest, USA, generates Great (megathrust) earthquakes with a recurrence period of about 500 years, most recently the M~9 event on January 26, 1700. Since no earthquake of such magnitude has occurred in the Pacific Northwest since the deployment of strong ground motion instruments, a large uncertainty is associated with the ground motions expected from such event. To decrease this uncertainty, we have carried out the first 3D simulations of megathrust earthquakes (Mw8.5 and Mw9.0) rupturing along the Cascadia subduction zone. The simulations were carried out in a recently developed 3D velocity model of the region of dimensions 1050 km by 550 km, discretized into 2 billion 250 m3 cubes with a minimum S-wave velocity of 625 m/s. The model includes the subduction slab, accretionary sediments, local sedimentary basins, and the ocean layer. About 6 minutes of wave propagation for each scenario consumed about 24 Wall-clock hours using a parallel fourth-order finite-difference method with 1600 processors on the San Diego Supercomputer Center Datastar supercomputer. The source descriptions for the Mw9.0 scenarios were designed by mapping the inversion results for the December 26, 2004 M9+ Sumatra-Andaman Islands earthquake (Ji, 2006) onto a 950 km by 150 km large rupture for the Pacific Northwest model. Simulations were carried out for hypocenters located toward the northern and southern ends of the subduction zone. In addition, we simulated two M8.5 events with a source area of 275 km by 150 km located in the northern and central parts of the model area. The sources for the M8.5 events were generated using the pseudo-dynamic model by Guatteri et al. (2004). All sources used spatially-variable slip, rise time and rupture velocity. Three major metropolitan areas are located in the model region, namely Seattle (3 million+ people), Vancouver (2 million+ people), and Portland (2 million+ people), all located above sedimentary basins amplifying the waves incident from the subduction zone. The estimated peak ground velocities (PGVs) for frequencies less than 0.5 Hz vary significantly with the assumed rise time. Using a mean rise of 32 s, as estimated from source inversion of the 2004 M9+ Sumatra-Andeman event (Ji, 2006), PGVs reached 40 cm/s in Seattle and 10 cm/s in Vancouver and Portland. However, if the mean rise time is decreased to about 14 s, as suggested by the empirical regression by Somerville et al. (1999), PGVs are increased by 2-3 times at these locations. For the Mw8.5 events, PGVs would reach about 10 cm/s in Seattle, and about 5 cm/s in Vancouver and Portland. Combined with extended duration of the shaking exceeding 1 minute for the Mw8.5 events and 2 minutes for the Mw9 events, these long-period ground motions may inflict significant damage on the built environment, in particular on the highrises in downtown Seattle. However, the strongest shaking arrives 1-2 minutes after the earthquake nucleates, indicating that an early warning system in place may help mitigate loss of life in case of a megathrust earthquake in the Pacific Northwest. Additional efforts should analyse the simulated displacements on the ocean bottom for tsunami generation potential.
Chemical Transformation of Market Waste Anaerobic Degradation in Recirculation and Non-recirculation System
Cheevanuch Tubtong; Sirintornthep Towprayoon; Pawinee Chaiprasert; Annop Nopharatana; Pantip Kayee
The batch studies of 30 kg. market waste (Cabbage 40%, Chinese cabbage 20%, other vegetable 20% and fruit 20%) anaerobic degradation was conducted in the lab scale units. These studies investigated the chemical transformation of organic degradation under anaerobic condition with and without the application of leachate recirculation. The chemical transformation focused on chemical oxygen demand (COD) and total volatile
Pressure transducer for exhaust gas recirculation system
Bradshaw, C.E.
A pressure transducer for use in internal combustion engine exhaust gas recirculation systems is disclosed having low inertia moving components for improved response time and a low cost diaphragm mounting arrangement. Upper and lower housing shells define in cooperation with a diaphragm and an upperand lower reaction plates fabricated from light weight plastic, a vacuum chamber, control chamber and a vent chamber. The single diaphragm is connected to the inner wall of the housing by a clamping ring, thereby dividing the diaphragm into individually pressure responsive upper and lower portions.
Removal of naphthalene from recirculated wash oil
Burcaw, K.R.; Watkins, R.E.
A bleed stream from the recirculating wash oil in a final cooling system for coke oven gas is centrifugally separated into a waste water stream, a sludge stream and a clean, dry oil stream which is substantially free of solids and has a water content less than 0.5% (Wt.). The clean, dry oil stream is heated to less than about 160/sup 0/C., preferably 125/sup 0/-135/sup 0/C, before entering a naphthalene stripper-wash oil still.
Preoperational test report, recirculation ventilation systems
Clifton, F.T.
This represents a preoperational test report for Recirculation Ventilation Systems, Project W-030. Project W-030 provides a ventilation upgrade for the four Aging Waste Facility tanks. The system provides vapor space cooling of tanks AY1O1, AY102, AZ1O1, AZ102 and supports the ability to exhaust air from each tank. Each system consists of a valved piping loop, a fan, condenser, and moisture separator; equipment is located inside each respective tank farm in its own hardened building. The tests verify correct system operation and correct indications displayed by the central Monitor and Control System.
Recirculating Linear Accelerators for Future Muon Facilities
S.A. Bogacz, K.B.Beard, R.P. Johnson
Neutrino Factories (NF) and Muon Colliders (MC) require rapid acceleration of short-lived muons to multi-GeV and TeV energies. A Recirculating Linear Accelerator (RLA) that uses superconducting RF structures can provide exceptionally fast and economical acceleration to the extent that the focusing range of the RLA quadrupoles allows each muon to pass several times through each high-gradient cavity. A new concept of rapidly changing the strength of the RLA focusing quadrupoles as the muons gain energy is being developed to increase the number of passes that each muon will make in the RF cavities, leading to greater cost effectiveness.
On the internal structure and mechanics of large strike-slip fault zones: field observations of the Carboneras fault in southeastern Spain
NASA Astrophysics Data System (ADS)
Faulkner, D. R.; Lewis, A. C.; Rutter, E. H.
Deciphering the internal structure of large fault zones is fundamental if a proper understanding is to be gained of their mechanical, hydrological and seismological properties. To this end, new detailed mapping and microstructural observations of the excellently exposed Carboneras fault zone in southeastern Spain have been used to elucidate both the internal arrangement of fault products and their likely mechanical properties. The fault is a 40 km offset strike-slip fault, which constitutes part of the Africa-Iberia plate boundary. The zone of faulting is 1 km in width not including the associated damage zone surrounding the fault. It is composed of continuous strands of phyllosilicate-rich fault gouge that bound lenses of variably broken-up protolith. This arrangement provides a number of fluid flow and fluid sealing possibilities within the fault zone. The gouge strands exhibit distributed deformation and are inferred to have strain hardening and/or velocity hardening characteristics. Also included in the fault zone are blocks of dolomite that contain thin (<1 cm thick) fault planes inferred to have been produced by strain weakening/velocity weakening behaviour. These fault planes have a predominantly R 1 Riedel shear orientation and are arranged in an en echelon pattern. A conceptual model of this type of wide fault zone is proposed which contrasts with previous narrow fault zone models. The observed structural and inferred mechanical characteristics of the Carboneras fault zone are compared to seismological observations of the San Andreas fault around Parkfield, CA. Similarities suggest that the Carboneras fault structure may be a useful analogue for this portion of the San Andreas fault at depth.
On the Internal Structure and Mechanics of Large Strike-Slip Fault Zones: Field Observations of the Carboneras Fault in Southeastern Spain
NASA Astrophysics Data System (ADS)
Faulkner, D. R.; Lewis, A. C.; Rutter, E. H.
Deciphering the internal structure of large fault zones is fundamental if a proper understanding is to be gained of their mechanical, hydrological and seismological properties. To this end, new detailed mapping and microstructural observations of the excellently exposed Carboneras fault zone in southeastern Spain has been used to elucidate both the internal arrangement of fault products and their likely mechanical properties. The fault is a 40 km offset strike-slip fault, which constitutes part of the Africa - Iberia plate boundary. The fault zone is ~1 km in width not including the associated damage zone surrounding the fault. It is composed of continuous strands of phyllosilicate-rich fault gouge which exhibit distributed deformation and are inferred to have strain hardening and velocity hardening characteristics. Included within the gouge bands are lenses of variably broken-up protolith. This arrangement provides a number of fluid flow and fluid sealing possibilities within the fault zone. Also included in the fault zone are blocks of dolomite, which contain thin (<1 cm thick) fault planes, inferred to have been produced by strain weakening/velocity weakening behavior. These fault planes have a R1 Riedel shear orientation and are arranged in an en-echelon pattern. A conceptual model of this type of wide fault zone is proposed which contrasts with previous narrow fault zone models. The observed structural and inferred mechanical characteristics of the Carboneras fault zone are compared to seismological observations of the San Andreas fault around Parkfield, California. Similarities suggest that the Carboneras fault structure may be a useful analogue for this portion of the San Andreas fault.
Full-scale demonstration of in situ cometabolic biodegradation of trichloroethylene in groundwater 1. Dynamics of a recirculating well system
NASA Astrophysics Data System (ADS)
Gandhi, Rahul K.; Hopkins, Gary D.; Goltz, Mark N.; Gorelick, Steven M.; McCarty, Perry L.
Recirculating well systems provide an engine for the in situ treatment of subsurface contaminants. Although numerous recirculating wells have been installed in the field, for such systems, there is a paucity of comprehensive monitoring data and models constrained to data appearing in the research literature. Here we present an extensive data set combined with detailed inverse and simulation analyses for a two-well groundwater recirculation system used for in situ bioremediation at Edwards Air Force Base in southern California. The ``conveyor belt'' flow system, which was established for in situ treatment of trichloroethylene (TCE) in two bioactive zones, was created by pumping water upward in one well and downward in another well, each well being screened in both the upper and lower aquifers. A bromide tracer test was conducted and extensively monitored for 60 days. Combined inverse analysis was conducted on hydraulic heads from 38 monitoring wells, 32 bromide concentration histories, and a constraint on the degree of recirculation that was based on TCE concentration data. Four different formulations involving alternative weighting schemes used in a nonlinear weighted least squares simulation-regression analysis were explored. The best formulation provided parameter estimates with tight bounds on estimated covariances, suggesting that the model provides a reasonable description of the hydrogeologic system. Our investigation indicates the geometry of the recirculation zone and the degree of recirculation under two different sets of operating conditions. Surprisingly, our analysis suggests that the effects of aquifer heterogeneity are not significant at this site under the conditions of forced recirculation. Furthermore, anomalous flow through an open monitoring well created significant vertical short-circuiting between the generally insulated aquifers. Flow through this small open conduit was equivalent to as much as 33% of the flow through the pumping wells. Using the model as a guide, we treated the aquifer system and bioactive zones as an equivalent mixed reactor to develop simple expressions relating effluent concentrations to influent concentrations. We demonstrate how these expressions are useful in predicting the removal of TCE that had undergone in situ bioremediation in the recirculatory treatment well system. The finite element model developed in this work serves as the foundation for a reactive transport simulator that we developed to analyze bioremediation which occurred during a 444 day experiment [Gandhi et al., 2002].
Johnson, Rolland PAUL
Since the muon has a short lifetime, fast acceleration is essential for high-energy applications such as muon colliders, Higgs factories, or neutrino factories. The best one can do is to make a linear accelerator with the highest possible accelerating gradient to make the accelerating time as short as possible. However, the cost of such a single linear accelerator is prohibitively large due to expensive power sources, cavities, tunnels, and related infrastructure. As was demonstrated in the Thomas Jefferson Accelerator Facility (Jefferson Lab) Continuous Electron Beam Accelerator Facility (CEBAF), an elegant solution to reduce cost is to use magnetic return arcs to recirculate the beam through the accelerating RF cavities many times, where they gain energy on each pass. In such a Recirculating Linear Accelerator (RLA), the magnetic focusing strength diminishes as the beam energy increases in a conventional linac that has constant strength quadrupoles. After some number of passes the focusing strength is insufficient to keep the beam from going unstable and being lost. In this project, the use of fast pulsed quadrupoles in the linac sections was considered for stronger focusing as a function of time to allow more successive passes of a muon beam in a recirculating linear accelerator. In one simulation, it was shown that the number of passes could be increased from 8 to 12 using pulsed magnet designs that have been developed and tested. This could reduce the cost of linac sections of a muon RLA by 8/12, where more improvement is still possible. The expense of a greater number of passes and corresponding number of return arcs was also addressed in this project by exploring the use of ramped or FFAG-style magnets in the return arcs. A better solution, invented in this project, is to use combined-function dipole-quadrupole magnets to simultaneously transport two beams of different energies through one magnet string to reduce costs of return arcs by almost a factor of two. A patent application was filed for this invention and a detailed report published in Physical Review Special Topics. A scaled model using an electron beam was developed and proposed to test the concept of a dog bone RLA with combined-function return arcs. The efforts supported by this grant were reported in a series of contributions to particle accelerator conferences that are reproduced in the appendices and summarized in the body of this report.
Swirling flow in model of large two-stroke diesel engine
NASA Astrophysics Data System (ADS)
Meyer, K. E.; Ingvorsen, K. M.; Mayer, S.; Walther, J. H.
In large two-stroke uniflow scavenged marine diesel engines fresh air is blown in through angled ports in the bottom of the cylinder liner forcing the burned gas out through an exhaust valve in the cylinder head. The scavenging flow is a transient (opening/closing ports) confined port-generated turbulent swirling flow, with complex phenomena such as central recirculation zones, vortex breakdown and vortex precession. A scale model of a simplified cylinder is created with a transparent cylinder five diameters long. The flow in the experiment has a Reynolds number of 50,000 based on the cylinder diameter and bulk velocity. Stereoscopic Particle Image Velocimetry (PIV) is used to investigate the flow for cases with both static and moving piston. Port angles of 0, 10, 20 and 30 degrees are considered. Although the flow has a relatively low swirl number of around 0.4, a central recirculation zone is observed indicating a vortex breakdown. The steady flow is analyzed with proper orthogonal decomposition revealing systematic variations in the shape and location of the vortex core. Transient measurements using phase-locked PIV are carried out with moving piston. The transient measurements reveal a sudden rapid change in flow topology as a central recirculation zone is formed. Also at: Computational Science and Engineering Laboratory, ETH Zurich, Universitatsstrasse 6, CH-8092 Zurich, Switzerland.
Determining the extent and characteristics of overrepresentation of large truck crashes in daytime and nighttime work zones
Mokkapati, Naveen
, extra work, and distractions for supervisors and coworkers that injuries cause. Traffic delay costs including value of time lost in traffic jams caused by crashes. Property damage costs including costs to repair or replace damaged vehicles... percent in passenger vehicles. TECHNOLOGIES USED TO IMPROVE WORK ZONE SAFETY In this sub-section, the researcher looked into previous research examining various technologies to improve work zone safety of both trucks and automobiles. Work Zone...
Recirculating Planar Magnetron Modeling and Experiments
NASA Astrophysics Data System (ADS)
Franzi, Matthew; Gilgenbach, Ronald; Hoff, Brad; French, Dave; Lau, Y. Y.
We present simulations and initial experimental results of a new class of crossed field device: Recirculating Planar Magnetrons (RPM). Two geometries of RPM are being explored: 1) Dual planar-magnetrons connected by a recirculating section with axial magnetic field and transverse electric field, and 2) Planar cathode and anode-cavity rings with radial magnetic field and axial electric field. These RPMs have numerous advantages for high power microwave generation by virtue of larger area cathodes and anodes. The axial B-field RPM can be configured in either the conventional or inverted (faster startup) configuration. Two and three-dimensional EM PIC simulations show rapid electron spoke formation and microwave oscillation in pi-mode. Smoothbore prototype axial-B RPM experiments are underway using the MELBA accelerator at parameters of -300 kV, 1-20 kA and pulselengths of 0.5-1 microsecond. Implementation and operation of the first RPM slow wave structure, operating at 1GHz, will be discussed. Research supported by AFOSR, AFRL, L-3 Communications, and Northrop Grumman. Done...processed 1830 records...17:52:57 Beginning APS data extraction...17:52:57
High speed exhaust gas recirculation valve
Fensom, Rod (Peterborough, GB); Kidder, David J. (Peterborough, GB)
In order to minimize pollutants such as Nox, internal combustion engines typically include an exhaust gas recirculation (EGR) valve that can be used to redirect a portion of exhaust gases to an intake conduit, such as an intake manifold, so that the redirected exhaust gases will be recycled. It is desirable to have an EGR valve with fast-acting capabilities, and it is also desirable to have the EGR valve take up as little space as possible. An exhaust gas recirculation valve is provided that includes an exhaust passage tube, a valve element pivotally mounted within the exhaust passage tube, a linear actuator; and a gear train. The gear train includes a rack gear operatively connected to the linear actuator, and at least one rotatable gear meshing with the rack gear and operatively connected to the valve element to cause rotation of the valve element upon actuation of the linear actuator. The apparatus provides a highly compact package having a high-speed valve actuation capability.
A nitrogen budget for a closed, recirculating mariculture system
Eric S. Thoman; Ellery D. Ingall; D. Allen Davis; Connie R. Arnold
Nitrogen dynamics were evaluated in a closed, recirculating mariculture system by constructing a mass and isotopic balance of all major nitrogen pools. The experimental system consisted of 12?238-l, closed, independent, recirculating systems, each containing red drum (Sciaenopsocellatus), a biological filter, water pump and subsurface aeration. The standard system used in our laboratory was compared to two treatments in order to
Water quality trials in four recirculating aquacultural system configurations
Sahdev Singh; James Ebeling; Fredrick Wheaton
Four circular, 2000-l, fiberglass tanks in four independent, indoor recirculating aquacultural systems were stocked with hybrid striped bass fingerlings (60-g average weight) at similar densities (320 fish\\/tank at the start of the study). The four systems represented four different recirculating system configurations as obtained by the combination of two types of biofilters (trickling and bead) and two types of solids
General noise analysis of recirculating delay line structures
Eric C. Heyde
Recirculating delay lines have value notably as sensors and optical signal processors. One of their main limitations is that phase noise from the source is converted to amplitude noise at the detector and that intensity noise is also filtered by the system. An expression is derived for the filtering effect that a recirculating delay line topology has on both the
Control strategies for domestic hot water recirculation systems
Goldner, F.S.
The purpose of a domestic hot water (DHW) recirculation system is to decrease the time spent waiting for the water to be delivered at acceptable temperatures when called for and also decrease the subsequent water consumption. The research detailed in this paper considered whether it is necessary to continuously run these recirculation pumps, as is general practice, or whether it is possible to reduce DHW system energy consumption by operating these pumps with some type of control strategy. Three different control strategies were evaluated by employing detailed monitoring. The different operating modes were: (1) base case (continuous operation), (2) shutdown during the overnight period, (3) shutdown during the peak morning and evening periods, and (4) cycling by a return line aquastat set at 110 F (61 C). In order to accomplish the research, six sites each had an aquastat installed onto the DHW return line and a programmable timeclock wired into the pump. The analysis identifies the relative energy use for each of the strategies during four round-robin rounds of two weeks each during the spring, summer, fall, and winter periods. When compared to the base case, (pump running 24 hours per day), Strategy B saves an average of 6%, Strategy C saves 6%, and Strategy D saves 11% of the DHW portion of a building's DHW energy requirements annually. This is significant in that for Strategy D, this translates into a savings of 4% of the building's total annual fuel bill. All of the control strategies evaluated were simple and employed low-cost devices (under $250 installed), which should help in achieving an extremely large implementation rate for the control strategy recommended. Tenant water quality survey questionnaires show that there was always an acceptable level of satisfaction, regardless of system control strategy.
The impact of predation by burbot ( Lota lota L.) on the macroinvertebrate community in the littoral zone of a large lake
Daniel Baumgðrtner; Karl-Otto Rothhaupt
We studied the effects of predation by juvenile burbot (Lota lota) on the macroinvertebrate community in mesocosm experiments in the stony littoral zone of Lake Constance, a large prealpine lake in Central Europe. Although the growth data of the burbot suggest that the benthivorous fish exerts strong predation pressure on the invertebrate community, the predicted level of consumption is only
Growth and Culture of Larval and Juvenile Tautogs in a Closed Recirculating-Seawater System
Dean M. Perry; Renee Mercaldo-Allen; Stacy Burgh
Field-captured and laboratory-held adult tautogs Tautoga onitis were allowed to spawn naturally under laboratory conditions. Embryos were cultured to hatching and raised successfully through the larval stage to 490-d-old posthatch juveniles. A large (8,500-L), closed, recirculating-seawater system, designed with a biological filter containing air diffusers that passed a strong air?water mixture through a high-surface-area substrate, was used to culture the
Late Pleistocene and Holocene paleoseismology of an intraplate seismic zone in a large alluvial valley, the New Madrid seismic zone, Central USA
NASA Astrophysics Data System (ADS)
Guccione, Margaret J.
The New Madrid seismic zone (NMSZ) is an intraplate right-lateral strike-slip and thrust fault system contained mostly within the Mississippi Alluvial Valley. The most recent earthquake sequence in the zone occurred in 1811 1812 and had estimated moment magnitudes of 7 8 (e.g., [Johnston, A.C., 1996. Seismic moment assessment of stable continental earthquakes, Part 3: 1811 1812 New Madrid, 1886 Charleston, and 1755 Lisbon. Geophysical Journal International 126, 314 344; Johnston, A.C., Schweig III, E.S, 1996. The enigma of the New Madrid earthquakes of 1811 1812. Annual Reviews of Earth and Planetary Sciences 24, 339 384; Hough, S.E., Armbruster, J.G., Seeber, L., Hough, J.F., 2000. On the modified Mercalli intensities and magnitudes of the New Madrid earthquakes. Journal of Geophysical Research 105 (B10), 23,839 23,864; Tuttle, M.P., 2001. The use of liquefaction features in paleoseismology: Lessons learned in the New Madrid seismic zone, central United States. Journal of Seismology 5, 361 380]). Four earlier prehistoric earthquakes or earthquake sequences have been dated A.D. 1450 Ý 150, 900 Ý 100, 300 Ý 200, and 2350 B.C. Ý 200 years using paleoliquefaction features, particularly those associated with native American artifacts, and in some cases surface deformation ([Craven, J. A. 1995. Paleoseismology study in the New Madrid seismic zone using geological and archeological features to constrain ages of liquefaction deposits. M.S thesis, University of Memphis, Memphis, TN, U.S.A.; Tuttle, M.P., Lafferty III, R.H., Guccione, M.J., Schweig III, E.S., Lopinot, N., Cande, R., Dyer-Williams, K., Haynes, M., 1996. Use of archaeology to date liquefaction features and seismic events in the New Madrid seismic zone, central United States. Geoarchaeology 11, 451 480; Guccione, M.J., Mueller, K., Champion, J., Shepherd, S., Odhiambo, B., 2002b. Stream response to repeated co-seismic folding, Tiptonville dome, western Tennessee. Geomorphology 43(2002), 313 349; Tuttle, M.P., Schweig, E.S., Sims, J.D., Lafferty, R.H., Wolf, L.W., Haynes, M.L., 2002. The earthquake potential of the New Madrid seismic zone, Bulletin of the Seismological Society of America, v 92, n. 6, p. 2080 2089; Tuttle, M.P., Schweig III, E.S., Campbell, J., Thomas, P.M., Sims, J.D., Lafferty III, R.H., 2005. Evidence for New Madrid earthquakes in A.D. 300 and 2350 B.C. Seismological Research Letters 76, 489 501]). The two most recent prehistoric and the 2350 B.C. events were probably also earthquake sequences with approximately the same magnitude as the historic sequence. Surface deformation (faulting and folding) in an alluvial setting provides many examples of stream response to gradient changes that can also be used to date past earthquake events. Stream responses include changes in channel morphology, deviations in the channel path from the regional gradient, changes in the direction of flow, anomalous longitudinal profiles, and aggradation or incision of the channel ([Merritts, D., Hesterberg, T, 1994. Stream networks and long-term surface uplift in the New Madrid seismic zone. Science 265, 1081 1084.; Guccione, M.J., Mueller, K., Champion, J., Shepherd, S., Odhiambo, B., 2002b. Stream response to repeated co-seismic folding, Tiptonville dome, western Tennessee. Geomorphology 43 (2002), 313 349]). Uplift or depression of the floodplain affects the frequency of flooding and thus the thickness and style of vertical accretion or drowning of a meander scar to form a lake. Vegetation may experience trauma, mortality, and in some cases growth enhancement due to ground failure during the earthquake and hydrologic changes after the earthquake ([VanArdale, R.B., Stahle, D.W., Cleaveland, M.K., Guccione, M.J., 1998. Earthquake signals in tree-ring data from the New Madrid seismic zone and implications for paleoseismicity. Geology 26, 515 518]). Identification and dating these physical and biologic responses allows source areas to be identified and seismic events to be dated. Seven fault segments are recognized by microseismicity and geomorphology. Surface faulting
Recirculating Molten Metal Supply System And Method
Kinosz, Michael J. (Apollo, PA); Meyer, Thomas N. (Murrysville, PA)
The melter furnace includes a heating chamber (16), a pump chamber (18), a degassing chamber (20), and a filter chamber (22). The pump chamber (18) is located adjacent the heating chamber (16) and houses a molten metal pump (30). The degassing chamber (20) is located adjacent and in fluid communication with the pump chamber (18), and houses a degassing mechanism (36). The filter chamber (22) is located adjacent and in fluid communication with the degassing chamber (20). The filter chamber (22) includes a molten metal filter (38). The melter furnace (12) is used to supply molten metal to an externally located holder furnace (14), which then recirculates molten metal back to the melter furnace (12).
Brillouin Flow in Recirculating Planar Magnetron
NASA Astrophysics Data System (ADS)
Simon, D. H.; Lau, Y. Y.; Franzi, M.; Greening, G.; Gilgenbach, R. M.
We examine the Brillouin flow in the conventional magnetron, inverted magnetron, and planar magnetron, with respect to the equilibrium, stability, and operating conditions. This renewed interest was prompted by our recent invention of the recirculating planar magnetron (RPM), where rapid start up utilizes the negative mass instability in the inverted magnetron configuration. Given that Brillouin flow is the most likely state in a crossed-field gap, and that various embodiments of the RPM consist of the conventional, inverted, and planar magnetron, it is necessary to study equilibrium, stability, and operating conditions at the same footing. To study startup, we solve the eigenvalue problem that governs the stability of Brillouin flow, including the effects of the resonant cavities that form the slow wave structures. We examine the Brillouin flow in the conventional magnetron, inverted magnetron, and planar magnetron, with respect to the equilibrium, stability, and operating conditions. This renewed interest was prompted by our recent invention of the recirculating planar magnetron (RPM), where rapid start up utilizes the negative mass instability in the inverted magnetron configuration. Given that Brillouin flow is the most likely state in a crossed-field gap, and that various embodiments of the RPM consist of the conventional, inverted, and planar magnetron, it is necessary to study equilibrium, stability, and operating conditions at the same footing. To study startup, we solve the eigenvalue problem that governs the stability of Brillouin flow, including the effects of the resonant cavities that form the slow wave structures. Work supported by AFOSR (grant #: FA9550-10-1-0104), and L-3 Communications Electron Devices.
Recirculating planar magnetrons: simulations and experiment
Franzi, Matthew; Gilgenbach, Ronald; French, David; Lau, Y.Y.; Simon, David [Plasma, Pulsed Power and Microwave Lab., Nuclear Engineering and Radiological Sciences Department, University of Michigan, Ann Arbor, Ml (United States); Hoff, Brad [Air Force Research Lab., Kirtland AFB, NM (United States); Luginsland, John W. [Air Force Office of Scientific Research, Arlington, VA (United States)
The Recirculating Planar Magnetron (RPM) is a novel crossed-field device whose geometry is expected to reduce thermal load, enhance current yield as well as ease the geometric limitations in scaling to high RF frequencies as compared to the conventional cylindrical magnetrons. The RPM has two different adaptations: A. Axial B field and radial E field; B. Radial B field and axial E field. The preliminary configuration (A) to be used in experiments at the University of Michigan consists of two parallel planar sections which join on either end by cylindrical regions to form a concentric extruded ellipse. Similar to conventional magnetrons, a voltage across the AK gap in conjunction with an axial magnetic field provides the electrons with an ExB drift. The device is named RPM because the drifting electrons recirculate from one planar region to the other. The drifting electrons interact with the resonantly tuned slow wave structure on the anode causing spoke formation. These electron spokes drive a RF electric field in the cavities from which RF power may be extracted to Waveguides. The RPM may be designed in either a conventional configuration with the anode on the outside, for simplified extraction, or as an inverted magnetron with the anode at the inner conductor, for fast start-up. Currently, experiments at the Pulsed Power and Microwave Laboratory at the University of Michigan are in the setup and design phase. A conventional RPM with planar cavities is to be installed on the Michigan Electron Long Beam Accelerator (MELBA) and is anticipated to operate at -200kV, 0.2T with a beam current of 1-10 kA at 1GHz. The conventional RPM consists of 12 identical planar cavities, 6 on each planar side, with simulated quality factor of 20.
Determining the extent and characteristics of overrepresentation of large truck crashes in daytime and nighttime work zones
Mokkapati, Naveen
to identify the possible reasons and countermeasures for any disproportionate change in truck to automobile crashes. The identified list of countermeasures includes the use of law enforcement, a smart work zone system, a dynamic late merge system, CMS...
Determining the extent and characteristics of overrepresentation of large truck crashes in daytime and nighttime work zones
Mokkapati, Naveen
to identify the possible reasons and countermeasures for any disproportionate change in truck to automobile crashes. The identified list of countermeasures includes the use of law enforcement, a smart work zone system, a dynamic late merge system, CMS...
Determining the extent and characteristics of overrepresentation of large truck crashes in daytime and nighttime work zones
Mokkapati, Naveen
The growth of vehicle travel in the United States has accelerated wear on the interstate highway system leading to frequent pavement repair and rehabilitation projects. The presence of work zones not only causes traffic congestion and backup...
Recirculating induction accelerators for inertial fusion: Prospects and status
Friedman, A.; Barnard, J.J.; Cable, M.D. [and others
The US is developing the physics and technology of induction accelerators for heavy-ion beam-driven inertial fusion. The recirculating induction accelerator repeatedly passes beams through the same set of accelerating and focusing elements, thereby reducing both the length and gradient of the accelerator structure. This promises an attractive driver cost, if the technical challenges associated with recirculation can be met. Point designs for recirculator drivers were developed in a multi-year study by LLNL, LBNL, and FM Technologies, and that work is briefly reviewed here. To validate major elements of the recirculator concept, we are developing a small (4-5-m diameter) prototype recirculator which will accelerate a space-charge-dominated beam of K{sup +} ions through 15 laps, from 80 to 320 keV and from 2 to 8 mA. Transverse beam confinement is effected via permanent-magnet quadrupoles; bending is via electric dipoles. This ``Small Recirculator`` is being developed in a build-and-test sequence of experiments. An injector, matching section, and linear magnetic channel using seven half-lattice periods of permanent-magnet quadrupole lenses are operational. A prototype recirculator half-lattice period is being fabricated. This paper outlines the research program, and presents initial experimental results.
Exhaust gas recirculation method for internal combustion engines
Kawanabe, T.; Kimura, K.; Asakura, M.; Shiina, T.
This patent describes a method of controlling exhaust gas recirculation in an internal combustion engine having an exhaust passage, an intake passage, an exhaust gas recirculating passage communicating the exhaust passage with the intake passage, and exhaust gas recirculating valve; and a transmission having a shift lever. The valve opening of the exhaust gas recirculating valve is controlled in response to operating conditions of the engine so as to regulate the amount of exhaust gas recirculation to values appropriate to the operating conditions of the engine. The method comprising the steps of (1) determining whether or not the engine is in at least one of a predetermined accelerating condition and a predetermined decelerating condition; (2) varying the valve opening of the exhaust gas recirculating valve by a predetermined value when the engine is determined to be in at least one of the predetermined accelerating condition and the predetermined decelerating condition; (3) detecting a position of the shift lever of the transmission; and (4) correcting the predetermined value in accordance with the detected position of the shift lever so as to increase the valve opening of the exhaust gas recirculating valve as the shift lever of the transmission is set to a higher speed position.
Large Eddy Simulations of forced ignition of a non-premixed bluff-body methane flame with Conditional Moment Closure
Triantafyllidis, A.; Mastorakos, E. [Hopkinson Laboratory, Department of Engineering, University of Cambridge, Cambridge CB2 1PZ (United Kingdom); Eggels, R.L.G.M. [Rolls Royce Deutschland, Blankenfelde-Mahlow (Germany)
Large Eddy Simulations (LES) of forced ignition of a bluff-body stabilised non-premixed methane flame using the Conditional Moment Closure (CMC) turbulent combustion model have been performed. The aim is to investigate the feasibility of the use of CMC/LES for ignition problems and to examine which, if any, of the characteristics already observed in related experiments could be predicted. A three-dimensional formulation of the CMC equation was used with simple and detailed chemical mechanisms, and sparks with different parameters (location, size) were used. It was found that the correct pattern of flame expansion and overall flame appearance were predicted with reasonable accuracy with both mechanisms, but the detailed mechanism resulted in expansion rates closer to the experiment. Moreover, the distribution of OH was predicted qualitatively accurately, with patches of high and low concentration in the recirculation zone during the ignition transient, consistent with experimental data. The location of the spark relative to the recirculation zone was found to determine the pattern of the flame propagation and the total time for the flame stabilisation. The size was also an important parameter, since it was found that the flame extinguishes when the spark is very small, in agreement with expectations from experiment. The stabilisation mechanism of the flame was dominated by the convection and sub-grid scale diffusion of hot combustion products from the recirculation zone to the cold gases that enter the burner, as revealed by analysis of the CMC equation. (author)
Peripheral regulatory T lymphocytes recirculating to the thymus suppress the development of their precursors.
Thiault, Nicolas; Darrigues, Julie; Adoue, VÕronique; Gros, Marine; Binet, BÕnÕdicte; Perals, Corine; Leobon, Bertrand; Fazilleau, Nicolas; Joffre, Olivier P; Robey, Ellen A; van Meerwijk, Joost P M; Romagnoli, Paola
Most T lymphocytes, including regulatory T cells (Treg cells), differentiate in the thymus. The age-dependent involution of this organ leads to decreasing production of T cells. Here we found that the output of new Treg cells from the thymus decreased substantially more than that of conventional T cells. Peripheral mouse and human Treg cells recirculated back to the thymus, where they constituted a large proportion of the pool of Treg cells and displayed an activated and differentiated phenotype. In the thymus, the recirculating cells exerted their regulatory function by inhibiting interleukin 2 (IL-2)-dependent de novo differentiation of Treg cells. Thus, Treg cell development is controlled by a negative feedback loop in which mature progeny cells return to the thymus and restrain development of precursors of Treg cells. PMID:25939024
Exogenous processes study in the coastal zone of the large reservoirs in the archaeological monuments placement (Volga-Kama region)
NASA Astrophysics Data System (ADS)
Gaynullin, Iskander; Usmanov, Bulat
The problem of conservation of archaeological heritage is highly relevant for the Republic of Tatarstan (RT), because in its territory identified, studied and registered around 4,300 archaeological sites. Most of archaeological sites from the Mesolithic to the late Middle Ages, now situated in the coastal zone of reservoirs where archaeological objects destroying because of intensive abrasion processes. The Volga and Kama rivers region attracted people for millennia. This territory of the Russian Plain is abounding in archaeological sites of various ages. During the Upper Paleolithic study region was quite convenient for living activity of the first inhabitants because of its situation out of the glacier limits. The sites on the banks are deposited within deluvial sediments of the Late Valday glaciation which have been accumulated on the slope of the Volga and Kama valleys, placing the third terrace and the segmentations of the second terrace over the flood-plain and now completely or fragmentary destroyed by reservoir waters. The analysis of remote sensing (1958-2013) and field survey (2011-2013) data performed. Georeferencing and alignment of the historical maps with remote sensing data makes possible to reveal mistakes in old site plans and re-create the shape of the destroyed archaeological objects, as well to get the exact size of the monument and its correct orientation. Results showed also that the studying sites caused a great rate of destruction of coastline. Cultural heritage sites monitoring, with information about the chronology, cultural layer value, settlement specifics, etc., taking into account the methods used in landscape ecology and field archaeological survey, allows to evaluate damage and the intensity of archaeological sites destruction through the dangerous exogenous processes estimation. Exogenous processes data and archaeological GIS integration will form unified system of archaeological rescue works, will provide analysis of large amount data in a short time, to update and enter new data, etc. This approach will help to determine the most problematic areas, in their funding valuation and archaeological excavations planning and broaden knowledge about the past of the peoples living in study region.
Pulsed Magnet Arc Designs for Recirculating Linac Muon Accelerators
K.B. Beard, R.P. Johnson, S.A. Bogacz, G.M. Wang
Recirculating linear accelerators (RLAs) using both pulsed quadrupoles and pulsed dipoles can be used to quickly accelerate muons in the 3 2000 GeV range. Estimates on the requirements for the pulsed quadrupoles and dipoles are presented.
Recirculation of Factory Heat and Air to Reduce Energy Consumption
Thiel, G. R.
Two methods for achieving substantial energy savings through recirculation techniques are discussed: 1. Air cleaning methods that can be used to recover the energy content of previously-exhausted ventilation air in many manufacturing plants...
Future of recirculating systems in the US aquaculture industry
Malone, R.F.
Recirculating systems consist of a culture unit, a recirculating pump, and a treatment block which facilitate extended re-use of water in the rearing of aquatic animals. As water re-use is extended from a few hours to months or even years, the complexity of the treatment block increases. Classified as either `open` with greater than 10 percent water replacement per day or `closed` with less than 10 percent daily replacement, most recirculating systems include aerators, clarifiers, and biofilters as key core elements. The aquaculture industry is increasingly facing a variety of socio-economic issues which will dramatically influence its future development. These problems range from increased competition for water rights through price depression and foreign imports to predation by protected migratory birds. As water-use, environmental, and conservation conflicts grow, the cost differences between the flow-through and closed production technologies will narrow, increasing the industry`s use of recirculating systems.
Field evaluation of a horizontal well recirculation system for groundwater treatment: Pilot test at the Clean Test Site Portsmouth Gaseous Diffusion Plant, Piketon, Ohio
Muck, M.T.; Kearl, P.M.; Siegrist, R.L. [and others] [and others
This report presents the results of field testing a horizontal well recirculation system at the Portsmouth Gaseous Diffusion Plant (PORTS). The recirculation system uses a pair of horizontal wells, one for groundwater extraction and treatment and the other for reinjection of treated groundwater, to set up a recirculation flow field. The induced flow field from the injection well to the extraction well establishes a sweeping action for the removal and treatment of groundwater contaminants. The overall purpose of this project is to study treatment of mixed groundwater contaminants that occur in a thin water-bearing zone not easily targeted by traditional vertical wells. The project involves several research elements, including treatment-process evaluation, hydrodynamic flow and transport modeling, pilot testing at an uncontaminated site, and pilot testing at a contaminated site. The results of the pilot test at an uncontaminated site, the Clean Test Site (CTS), are presented in this report.
Internal combustion engine with an exhaust gas recirculation system
Saiki, J.
Disclosed is an internal combustion engine with an exhaust gas recirculation system. The engine is provided with a carburetor which includes a primary system and a secondary system. The recirculated exhaust gas is supplied to the intake passage via an exhaust gas supply pipe which is disposed at a position downstream of the carburetor. The top end of the exhaust gas supply pipe is open at a space having a predetermined positional relationship with the wall of the primary system.
A micromechanical approach for simulating multiscale fabrics in large-scale high-strain zones: Theory and application
NASA Astrophysics Data System (ADS)
Jiang, Dazhi; Bentley, Callan
Deformation fabrics in Earth's crust and mantle are commonly used to constrain the tectonic history, deformation mechanisms, and rheological properties of the lithosphere. Their formation involves heterogeneous and multiscale deformation processes that current single-scale models cannot capture. Here we present a micromechanics-based MultiOrder Power Law Approach (MOPLA) for the simulation of multiscale fabrics in crustal scale high-strain zones. We consider the progressive deformation in a crustal high-strain zone on three different scales. On the macroscopic scale, representing the average assemblage of rock units at a point, we regard the rock mass as a continuum made of many first-order elements. The progressive deformation of first-order elements in the macroscopic flow field simulates tectonic transposition. On the scale of an individual first-order element, we regard it as an Eshelby inhomogeneity embedded in a poly element continuum. We apply Eshelby's inhomogeneity formalism for power law materials to relate the flow field inside a first-order element to the macroscopic flow field. On the scale pertinent to structures observed on the outcrop or smaller scale, the partitioned flow fields inside individual first-order elements are used to examine the fabric development. We implement MOPLA in MathCad, apply the approach to a natural example of the Cascade Lake shear zone, and discuss the implications of multiscale deformation. Our model predicts lineation patterns observed in natural high-strain zones that have remained unexplained by single-scale models.
Geothermal evidence for fluid flow through the gas hydrate stability field off Central Chile-transient flow related to large subduction zone earthquakes?
NASA Astrophysics Data System (ADS)
Grevemeyer, Ingo; Kaul, Norbert; Diaz-Naveas, Juan L.
Fluids are suspected to play a major role in the nucleation and rupture propagation of earthquakes. In Chile, seismological data were previously interpreted to indicate that fluids captured in the fault zone are released periodically during large underthrust earthquakes, leading to post-seismic fluid flow. In central Chile, heat flow derived from the presence of a bottom simulating reflector (BSR) show a smooth trend across the margin. BSR-derived data are in excellent agreement with thermal subduction zone models. Over the young accretionary prism, both BSR-derived and measured surface heat flow support a common trend. Landwards of the backstop, however, measured heat flow triples over a distance of 20-30 km, producing a profound discrepancy to the BSR-derived data. We suggest that this disparity is related to transient flow of warm fluids through the gas hydrate stability zone possibly caused by fluids released after large underthrust earthquakes. Such flow events may inherently affect the distribution of solid gas hydrates between the seafloor and the BSR.
The Physical, Geochemical and Microbial Conditions and Processes in the Hyporheic Zone of a Large Tidally Influenced River: The Fraser River, British Columbia, Canada
NASA Astrophysics Data System (ADS)
Bianchin, M.; Roschinski, T.; Ross, K.; Leslie, S.; William, M.; Beckie, R.
The objective of this research is to investigate the physical, chemical and biological conditions and processes that occur in the hyporheic zone of the lower Fraser River, British Columbia. The large flows of between 2000 and 10000 cubic meters per second, the 10 15 m deep, 250 m wide channel, the 1 m tidal fluctuations, the localized scour and redeposition of sediments during freshet and the strong geochemical contrast between groundwater and surface water distinguish this investigation from studies on smaller channels and streams and required the development of novel characterization tools and strategies. The geochemistry of water samples collected with a push-in profiler, bulk electrical conductivity (EC) measurements collected with a push-in tool and hydraulic head measurements indicate that groundwater principally discharges into the river approximately 100 m offshore in a 10 m wide band. River water and groundwater mix to a maximum depth of between 0.75 and 1.5 m. While hydraulic heads show strong tidal reversals, bulk EC profiles show only moderate changes during the tidal cycle. It was hypothesized that high iron (10's mg/L of Fe(II)) in reduced groundwater would precipitate from solution as secondary iron-oxide phases in the zone where groundwater mixes with aerobic river water. Sediments were collected with a freeze-shoe corer and depth profiles through the hyporheic zone and into the underlying aquifer were analyzed by selective extractions. The 15-30 mg/g of total extractable iron in both the aquifer and hyporheic zone is relatively high. The lack of noticeable iron accumulation in the hyporheic zone may indicate that iron precipitates on shallow sediments that are subsequently scoured from the river bed during freshet. Microbial DNA from sediments was analyzed using denaturing gradient gel electrophoresis and showed a relatively diverse community structure but an overall low biomass.
Tiny is mighty: seagrass beds have a large role in the export of organic material in the tropical coastal zone.
Gillis, Lucy G; Ziegler, Alan D; van Oevelen, Dick; Cathalot, Cecile; Herman, Peter M J; Wolters, Jan W; Bouma, Tjeerd J
Ecosystems in the tropical coastal zone exchange particulate organic matter (POM) with adjacent systems, but differences in this function among ecosystems remain poorly quantified. Seagrass beds are often a relatively small section of this coastal zone, but have a potentially much larger ecological influence than suggested by their surface area. Using stable isotopes as tracers of oceanic, terrestrial, mangrove and seagrass sources, we investigated the origin of particulate organic matter in nine mangrove bays around the island of Phuket (Thailand). We used a linear mixing model based on bulk organic carbon, total nitrogen and ?13C and ?15N and found that oceanic sources dominated suspended particulate organic matter samples along the mangrove-seagrass-ocean gradient. Sediment trap samples showed contributions from four sources oceanic, mangrove forest/terrestrial and seagrass beds where oceanic had the strongest contribution and seagrass beds the smallest. Based on ecosystem area, however, the contribution of suspended particulate organic matter derived from seagrass beds was disproportionally high, relative to the entire area occupied by mangrove forests, the catchment area (terrestrial) and seagrass beds. The contribution from mangrove forests was approximately equal to their surface area, whereas terrestrial contributions to suspended organic matter under contributed compared to their relative catchment area. Interestingly, mangrove forest contribution at 0 m on the transects showed a positive relationship with the exposed frontal width of the mangrove, indicating that mangrove forest exposure to hydrodynamic energy may be a controlling factor in mangrove outwelling. However we found no relationship between seagrass bed contribution and any physical factors, which we measured. Our results indicate that although seagrass beds occupy a relatively small area of the coastal zone, their role in the export of organic matter is disproportional and should be considered in coastal management especially with respect to their importance as a nutrient source for other ecosystems and organisms. PMID:25386853
Tiny Is Mighty: Seagrass Beds Have a Large Role in the Export of Organic Material in the Tropical Coastal Zone
Gillis, Lucy G.; Ziegler, Alan D.; van Oevelen, Dick; Cathalot, Cecile; Herman, Peter M. J.; Wolters, Jan W.; Bouma, Tjeerd J.
Ecosystems in the tropical coastal zone exchange particulate organic matter (POM) with adjacent systems, but differences in this function among ecosystems remain poorly quantified. Seagrass beds are often a relatively small section of this coastal zone, but have a potentially much larger ecological influence than suggested by their surface area. Using stable isotopes as tracers of oceanic, terrestrial, mangrove and seagrass sources, we investigated the origin of particulate organic matter in nine mangrove bays around the island of Phuket (Thailand). We used a linear mixing model based on bulk organic carbon, total nitrogen and ?13C and ?15N and found that oceanic sources dominated suspended particulate organic matter samples along the mangrove-seagrass-ocean gradient. Sediment trap samples showed contributions from four sources oceanic, mangrove forest/terrestrial and seagrass beds where oceanic had the strongest contribution and seagrass beds the smallest. Based on ecosystem area, however, the contribution of suspended particulate organic matter derived from seagrass beds was disproportionally high, relative to the entire area occupied by mangrove forests, the catchment area (terrestrial) and seagrass beds. The contribution from mangrove forests was approximately equal to their surface area, whereas terrestrial contributions to suspended organic matter under contributed compared to their relative catchment area. Interestingly, mangrove forest contribution at 0 m on the transects showed a positive relationship with the exposed frontal width of the mangrove, indicating that mangrove forest exposure to hydrodynamic energy may be a controlling factor in mangrove outwelling. However we found no relationship between seagrass bed contribution and any physical factors, which we measured. Our results indicate that although seagrass beds occupy a relatively small area of the coastal zone, their role in the export of organic matter is disproportional and should be considered in coastal management especially with respect to their importance as a nutrient source for other ecosystems and organisms. PMID:25386853
Elastic Properties of Subduction Zone Materials in the Large Shallow Slip Environment for the Tohoku 2011 Earthquake: Laboratory data from JFAST Core Samples
NASA Astrophysics Data System (ADS)
Jeppson, T.; Tobin, H. J.
The 11 March 2011 Tohoku-Oki earthquake (Mw=9.0) produced large displacements of ~50 meters near the Japan Trench. In order to understand earthquake propagation and slip stabilization in this environment, quantitative values of the real elastic properties of fault zones and their surrounding wall rock material is crucial. Because elastic and mechanical properties of faults and wallrocks are controlling factors in fault strength, earthquake generation and propagation, and slip stabilization, an understanding of these properties and their depth dependence is essential to understanding and accurately modeling earthquake rupture. In particular, quantitatively measured S-wave speeds, needed for estimation of elastic properties, are scarce in the literature. We report laboratory ultrasonic velocity measurements performed at elevated pressures, as well as the calculated dynamic elastic moduli, for samples of the rock surrounding the Tohoku earthquake principal fault zone recovered by drilling during IODP Expedition 343, Japan Trench Fast Drilling Project (JFAST). We performed measurements on five samples of gray mudstone from the hanging wall and one sample of underthrust brown mudstone from the footwall. We find P- and S-wave velocities of 2.0 to 2.4 km/s and 0.7 to 1.0 km/s, respectively, at 5 MPa effective pressure. At the same effective pressure, the hanging wall samples have shear moduli ranging from 1.4 to 2.2 GPa and the footwall sample has a shear modulus of 1.0 GPa. While these values are perhaps not surprising for shallow, clay-rich subduction zone sediments, they are substantially lower than the 30 GPa commonly assumed for rigidity in earthquake rupture and propagation models [e.g., Ide et al., 1993; Liu and Rice, 2005; Loveless and Meade, 2011]. In order to better understand the elastic properties of shallow subduction zone sediments, our measurements from the Japan Trench are compared to similar shallow drill core samples from the Nankai Trough, Costa Rica, Cascadia, and Barbados ridge subduction zones. We find that shallow subduction zone sediments in general have similarly low rigidity. These data provide important ground-truth values that can be used to parameterize fault slip models addressing the problem of shallow, tsunamigenic propagation of megathrust earthquakes.
Multiple trophic levels fueled by recirculation in the Columbia River plume
NASA Astrophysics Data System (ADS)
Kudela, Raphael M.; Horner-Devine, Alexander R.; Banas, Neil S.; Hickey, Barbara M.; Peterson, Tawnya D.; McCabe, Ryan M.; Lessard, Evelyn J.; Frame, Elizabeth; Bruland, Kenneth W.; Jay, David A.; Peterson, Jay O.; Peterson, William T.; Kosro, P. Michael; Palacios, Sherry L.; Lohan, Maeve C.; Dever, Edward P.
Large rivers represent gateways for the transport of terrigenous and anthropogenic material to the coastal ocean. Here we document a 700 km2 recirculation or bulge associated with the Columbia River plume that retains recently discharged river water sufficiently to create a regional bioreactor. Fueled by a fluvial nitrate source, this feature stimulated growth across three trophic levels and may buffer this gateway system during periods of increased warming and stratification that lead to decreased ocean productivity, potentially enhancing production at multiple trophic levels and enriching surface waters far from the river mouth.
Plume Generation Zones at the margins of Large Low Shear Velocity Provinces on the coremantle boundary
Kevin Burke; Bernhard Steinberger; Trond H. Torsvik; Mark A. Smethurst
Large Igneous Province (LIP) eruption sites of the past 300 My lie vertically above 1% slow shear wave velocity (Vs) contours bounding the African and Pacific Large Low Shear Velocity Provinces (LLSVPs) at the coremantle boundary (CMB), or in the cases of the Siberian and Columbia River LIPs, bounding one or other of two smaller, Low Shear Velocity Provinces (LSVPs). Steep
Towards the inclusion of wave-ice interactions in large-scale models for the Marginal Ice Zone
Williams, Timothy; Dumont, Dany; Squire, Vernon; Bertino, Laurent
A wave-ice interaction model for the marginal ice zone (MIZ) is reported, which involves both the attenuation of ocean surface waves by sea ice and the concomitant breaking of the ice by waves. It is specifically designed to embed wave-ice interactions in an operational ice/ocean model for the first time. We investigate different methods of including the wave forcing, and different criteria for determining if they cause floes to break. We also investigate and discuss the effects of using various attenuation models, finding that predicted MIZ widths are quite sensitive to the choice of model. Additional sensitivity tests are performed on: (i) different parameterizations of the floe size distribution (FSD), including the initial FSD used; (ii) the properties of the wave field; and (iii) the sea ice properties such as concentration, thickness and breaking strain. Results are relatively insensitive to FSD parameterization but vary noticeably and systematically with its initial configuration, as they do with prope...
Experimental investigation of reactive turbulent recirculating jet mixing in a dump
NASA Technical Reports Server (NTRS)
Smith, G. D.; Giel, T. V.; Catalano, C. G.
A ducted, subsonic, hydrogen air turbulent jet mixing flowfield was investigated, both with and without combustion. The geometric configuration was representative of a sudden expansion or dump combustor, with a central air jet surrounded by a low velocity hydrogen stream at an overall equivalence ratio of 0.12. The ratio of the duct to inner nozzle diameter was 2.5. Radial distributions of mean axial and radial velocity, axial and radial turbulent intensity, velocity cross correlation, gas composition, static temperature and total pressure, as well as axial distributions of wall static pressure, were obtained for axial stations from zero to six duct diameters from the combustor entrance. The data indicate that mixing is slower in the chemically reactive flow field than in the nonreactive flow field, and that the presence of combustion has a significant effect on the size and location of the recirculation zone within the mixing duct.
Occurrence of large temperature inversion in the thermohaline frontal zone at the Yellow Sea entrance in winter and its relation to advection
NASA Astrophysics Data System (ADS)
Lie, Heung-Jae; Cho, Cheol-Ho; Jung, Kyung Tae
inversion (higher temperature at a deeper depth) in winter and its relation to advection were investigated by analyzing both conductivity-temperature-depth data in the southern Yellow Sea (YS) and northwestern East China Sea during the winter of 2002-2003 and time series data of temperature, salinity, and currents at a buoy station at the YS entrance. Significant temperature inversions occur predominantly along the thermohaline front at the YS entrance where the Cheju Warm Current Water (CWCW) and the cold coastal waters meet. In February 2003, on the northern frontal zone along 34¯N where isotherms and isohalines declined downward to the north, particularly large inversions with temperature differences of larger than 2.0¯C were observed to occur more in troughs than in the crests of the wave-like frontal meander where the cold Korean coastal water (KCW) advances farther southward. The inversion persisted until mid-April at the buoy station in the frontal zone, and both temperature and salinity showed simultaneous variations in the same manner. During episodic occurrences of large inversions, temperature and salinity decreased sharply in the upper layer, but increased concurrently in the lower layer. These episodic inversions were found to be closely related to the westward advection of the KCW in the upper layer and the northward advection of the CWCW in the lower layer. It is considered that these advections may play an important role in maintaining baroclinicity in the northern frontal zone, which is responsible for driving the westward transversal flow across the YS entrance.
Supra-subduction and abyssal mantle peridotites of the Coast Range ophiolite, California: Initiation of Franciscan subduction along a large-offset fracture zone
NASA Astrophysics Data System (ADS)
Choi, S. H.; Shervais, J. W.; Mukasa, S. B.
The Coast Range ophiolite (CRO) of California is one of the most extensive tracts of oceanic crust preserved in the Cordillera, but its origin has long remained controversial. We present here new data on mineral compositions in mantle peridotites that underlie crustal sections of ophiolite, and show that these are dominantly refractory harzburgites related to high apparent melting in a supra-subduction zone (SSZ) setting. Abyssal peridotite occurs at one location, Stonyford, in the CRO where it is associated with SSZ mantle peridotite and volcanic rocks with both oceanic and arc-like geochemistry. SSZ mantle peridotites are associated with crustal sections containing arc-related volcanics, including boninites. This convergence between conclusions based on crustal lithologies and their underlying mantle sections confirms previous proposals that link the CRO to SSZ processes, and seriously undermines hypotheses that call on formation of the ophiolite at a mid-ocean ridge spreading center. We also report on the radiogenic isotope characteristics of peridotite clinopyroxenes. Based on the Sr-Nd-Pb-Hf isotopic compositions and estimated temperatures, we suggest that the abyssal peridotite block represents a remnant of large-offset transform oceanic lithosphere at >172 Ma. East-dipping, proto-Franciscan subduction is likely to have been initiated along this fault zone, which produced the supra-subduction zone (SSZ) peridotites in the CRO. We propose that the remnant abyssal peridotites represent a snapshot of the mantle wedge composition prior to overprinting of large sectors by hydrous melting during the subsequent subduction-controlled SSZ processes.
Effect of Two-Stage Injection on Unburned Hydrocarbon and Carbon Monoxide Emissions in Smokeless Low-Temperature Diesel Combustion with UltraHigh Exhaust Gas Recirculation
T Li; M Suzuki; H Ogawa
The unburned hydrocarbon (UHC) and carbon monoxide (CO) emissions from smokeless low-temperature diesel combustion (LTC) with ultra-high exhaust gas recirculation (EGR) can be attributed to lowered combustion temperatures as well as to under-mixing of fuel-rich mixture along the combustion chamber walls, overly mixed fuel-lean mixture at the spray tails, and fuel missing the piston bowl and entering the squish zones.
Low-head saltwater recirculating aquaculture systems utilized for juvenile red drum production
Technology Transfer Automated Retrieval System (TEKTRAN)
Recirculating aquaculture systems reuse water with mechanical and biological treatment between each use and thus require wastewater treatment techniques for continuous waste removal. However, the traditional techniques and equipment utilized in recirculating aquaculture systems are expensive. The d...
In-tank aeration, a necessary compliment of loaded systems in an airlift recirculating aquaculture system
Technology Transfer Automated Retrieval System (TEKTRAN)
Water treatment components in recirculating aquaculture systems in generally address solids removal, nitrification, circulation, aeration, and degasification. Airlift pumps in a recirculating aquaculture system can address water circulation, aeration, and degasification. Recent data indicates oxygen...
Large Earthquake Hazard of the San Jacinto Fault Zone, CA, from Long Record of Simulated Seismicity Assimilating the Available Instrumental and Paleoseismic Data
NASA Astrophysics Data System (ADS)
Z—ller, G.; Ben-Zion, Y.
We investigate spatio-temporal properties of earthquake patterns in the San Jacinto fault zone (SJFZ), California, between Cajon Pass and the Superstition Hill Fault, using a long record of simulated seismicity constrained by available seismological and geological data. The model provides an effective realization of a large segmented strike-slip fault zone in a 3D elastic half-space, with heterogeneous distribution of static friction chosen to represent several clear step-overs at the surface. The simulated synthetic catalog reproduces well the basic statistical features of the instrumental seismicity recorded at the SJFZ area since 1981. The model also produces events larger than those included in the short instrumental record, consistent with paleo-earthquakes documented at sites along the SJFZ for the last 1,400 years. The general agreement between the synthetic and observed data allows us to address with the long-simulated seismicity questions related to large earthquakes and expected seismic hazard. The interaction between m ? 7 events on different sections of the SJFZ is found to be close to random. The hazard associated with m ? 7 events on the SJFZ increases significantly if the long record of simulated seismicity is taken into account. The model simulations indicate that the recent increased number of observed intermediate SJFZ earthquakes is a robust statistical feature heralding the occurrence of m ? 7 earthquakes. The hypocenters of the m ? 5 events in the simulation results move progressively towards the hypocenter of the upcoming m ? 7 earthquake.
A simplified multi-zone model for determining the placement of bio-defense sensors in large buildings
Van Broekhoven, Scott B. (Scott Bennett)
The anthrax mailings of 2001 increased public and government awareness to the threat of bio-terrorism. Particularly vulnerable to a bio-terrorist event are large indoor facilities such as convention centers, office buildings, ...
Large-Scale Numerical Modeling of Flow and Transport in a Deep Unsaturated-Zone System for Natural and Artificial Recharge Analysis
NASA Astrophysics Data System (ADS)
Ellett, K. M.; Ellett, K. M.; Flint, A. L.; Flint, A. L.; Hopmans, J. W.
Investigations of deep unsaturated-zone systems have increased in recent years owing to a variety of issues including nuclear waste management, contaminant remediation, and population increases in semi-arid lands. While substantial insights have been realized in our understanding of such complex systems, challenges still remain in our ability to accurately simulate large-scale flow and transport processes. In the San Gorgonio Pass area near Beaumont, California, overdraft of ground-water resources has led to the development of a program that uses surface spreading of water from the California aqueduct to artificially recharge the local aquifer. The issues being addressed in the program are the characterization of the unsaturated zone beneath the artificial recharge ponds and the amount, timing, and location of artificially recharged water reaching the water table, including the interception of nitrates from nearby septic systems. A measurement scheme using surface and subsurface instrumentation and laboratory analyses was implemented to develop conceptual and numerical models of the deep unsaturated zone. The initial conceptual model was tested using a numerical model and was then modified to account for in situ measurements of temperature and matric potential. Transient one-dimensional flow modeling of vertical infiltration could reproduce the measured temperature and matric potential profiles, but could not account for all conceptual model components. Steady-state two-dimensional flow modeling more easily reproduced the temperature and matric potential profiles when cold-water infiltration occurred in a nearby (25 m) ephemeral stream. In either model, the hydraulic conductivity of a perching layer critical to the timing of recharge was estimated by inverse fitting the temperature profile between the perched water and the water table. A transient three-dimensional flow model that accounts for all components of the conceptual model was developed from the experience gained using the one and two-dimensional models, and was used to predict the amount, timing, and location of the artificial recharge for the San Gorgonio Pass area. Sensitivity analysis of space-time discretization was performed to illustrate the ability of existing models to accurately simulate large-scale hydrologic processes in the unsaturated zone.
An application of membrane inlet mass spectrometry to measure denitrification in a recirculating mariculture system
Mark J McCarthy; Wayne S Gardner
The detrimental effects of aquaculture waste discharges require development of recirculating and\\/or pretreatment systems. Denitrification, in combination with nitrification, removes fixed nitrogen from culture water in recirculating systems. Three experiments were conducted to measure denitrification rates in biofilter media (bioballs) and sediments from a recirculating mariculture system. In this case, sediments refer to solids accumulated at the bottom of the
Lattice design principles for a recirculated, high energy, SRF electron accelerator
David R. Douglas
Issues critical to the design of a high energy (over 10 GeV), recirculated, superconducting RF (SRF) based electron accelerator are discussed. These include injection energy, number of passes, type of linac focussing structure (constant gradient or constant focal length), quantum excitation in recirculation arcs, method of beam separation for recirculation, and use of isochronous or nonisochronous transport. An example lattice
Management Ability and the Economics of Recirculating Aquaculture Production Systems
Richard F. Kazmierczak Jr.; Rex H. Caffey
A bioeconomic model of fish growth in recirculating aquaculture systems was constructed by developing a bioenergetic model comprised of metabolic sub-models for growth, ammonia production, and oxygen consumption. Metabolite accumulations are determined by exogenous control variables for filtration and aeration and used to indirectly represent management ability. Numerical solutions to model parameters were obtained using a two point boundary shooting
10 Commercially Feasible Urban Recirculating Aquaculture: Addressing the Marine Sector
Yonathan Zohar; Yossi Tal; Harold Schreier; Colin Steven; John Stubblefield
With the global collapse of marine fisheries and the environmental issues associated with net-pen aquaculture practices, there is a pressing need to develop fully contained and environmentally sus- tainable approaches to producing seafood. Recirculating aquaculture systems (RAS), which provide this approach, have been widely used over the last two decades to farm freshwater species. However, the cost associated with the
Design criteria for recirculating, marine ornamental production systems
Craig A. Watson; Jeffrey E. Hill
While recirculating aquaculture systems for food animals are well defined in the literature, little information is available for the emerging production of high value marine ornamental species. These organisms typically require systems which operate within a narrow range of parameters compared to most food animals, and in addition to growth and survival issues, individual appearance of animals is critical to
Rating fixed film nitrifying biofilters used in recirculating aquaculture systems
Ronald F. Malone; Timothy J. Pfeiffer
Predicting the performance of biofilters is an engineering challenge that is critical to both designers and managers. The task is complicated by the wide variety of water quality expectations and environmental conditions displayed by a recirculating aquaculture system (RAS). A myriad of biofilters designs have been generated reflecting approaches of engineers attempting to maximize specific surface area and oxygen transfer
Ozone Application in Recirculating Aquaculture System: An Overview
Alex Augusto GonÓalves; Graham A. Gagnon
In recirculating aquaculture systems (RAS), particulates (including feces, uneaten feed, bacteria, and algae) can cause several problems, in that they may harbor pathogens, can physically irritate the fish, and upon decomposition, release ammonia and consume oxygen. Mechanical filters, foam fractionators, and other engineered devices are used to remove particles quickly from aquaculture systems, in order to improve fish health and
Anaerobic digestion of sludge from intensive recirculating aquaculture systems: Review
Natella Mirzoyan; Yossi Tal; Amit Gross
Intensive recirculating aquaculture systems (RAS) produce high volumes of biosolid waste which is a potential source of pollution if not properly treated. A reduction in sludge-mass would therefore minimize the potential environmental hazard and economic burden stemming from its disposal. Recently, anaerobic digestion was suggested as an alternative to aquaculture sludge digestion and stabilization in RAS. This practice results not
Application of airlift technology in recirculation aquaculture systems
Technology Transfer Automated Retrieval System (TEKTRAN)
Marine hatcheries implementing recirculating aquaculture technology require pristine water quality and must be designed to provide a disease free environment as much as possible to limit disease transmission. Given the aggressive nature of a variety of marine pathogens, design considerations with re...
Using exhaust gas recirculation in internal combustion engines: a review
G. H. Abd-Alla
The aim of this work is to review the potential of exhaust gas recirculation (EGR) to reduce the exhaust emissions, particularly NOX emissions, and to delimit the application range of this technique. A detailed analysis of previous and current results of EGR effects on the emissions and performance of Diesel engines, spark ignition engines and duel fuel engines is introduced.
Recirculating pump seal investigation. Final report. Volume 1
This report presents the results of a review of experience with reactor coolant and recirculating pump seal designs and pump seal auxiliary systems. The scope of this review includes all operating commercial light water reactors (LWRs) over 400 MWe in the United States. Problems which have been encountered with seals and seal auxiliary systems are discussed, the principal causes of
Principles of Water Recirculation and Filtration in Aquaculture 1
Watson, Craig A.
FA12 Principles of Water Recirculation and Filtration in Aquaculture 1 Michael McGee and Charles) removal of particulate matter, 3) biological filtration to remove waste ammonia and nitrite, and 4 and Filtration in Aquaculture 2 Removal of particulate matter Solids resulting from fish waste and uneaten feed
33 CFR 159.127 - Safety coliform count: Recirculating devices.
Code of Federal Regulations, 2011 CFR
...devices. Thirty-eight of forty samples of flush fluid from a recirculating device must have less than 240 fecal coliform bacteria per 100 milliliters. These samples must be collected in accordance with Ï 159.123(b) and tested in accordance with...
33 CFR 159.127 - Safety coliform count: Recirculating devices.
Code of Federal Regulations, 2012 CFR
...devices. Thirty-eight of forty samples of flush fluid from a recirculating device must have less than 240 fecal coliform bacteria per 100 milliliters. These samples must be collected in accordance with Ï 159.123(b) and tested in accordance with...
33 CFR 159.127 - Safety coliform count: Recirculating devices.
Code of Federal Regulations, 2014 CFR
...devices. Thirty-eight of forty samples of flush fluid from a recirculating device must have less than 240 fecal coliform bacteria per 100 milliliters. These samples must be collected in accordance with Ï 159.123(b) and tested in accordance with...
Tide-induced recirculation across the aquifer-ocean interface
C. Robinson; L. Li; H. Prommer
A parametric analysis is conducted to examine the influence of tides, inland hydraulic conditions, and aquifer properties on the rate of tide-induced seawater recirculation through the nearshore aquifer. Understanding such influence is crucial for accurate prediction of subsurface chemical fluxes to coastal waters via groundwater discharge. The analysis is based on numerical simulations of density-dependent groundwater flow in a coastal
Use of low temperature blowers for recirculation of hot gases
Maru, H.C.; Forooque, M.
An apparatus is described for maintaining motors at low operating temperatures during recirculation of hot gases in fuel cell operations and chemical processes such as fluidized bed coal gasification. The apparatus includes a means for separating the hot process gas from the motor using a secondary lower temperature gas, thereby minimizing the temperature increase of the motor and associated accessories.
An Inexpensive Recirculating Aquaculture System with Multiple Use Capabilities.
ERIC Educational Resources Information Center
Scurlock, Gerald Don, Jr.; Cook, S. Bradford; Scurlock, Carrie Ann
Describes the construction of an inexpensive recirculating aquaculture system that can hold up to 46 pounds of fish, invertebrates, and mussels for classroom use. The system is versatile, requires little maintenance, and can be used for both teaching and research purposes. (WRM)
Using Residence Time for the Extraction of Recirculation Regions
Peraire, Jaime
for the examination of 3D transient simulations. The final expression of this work will be a software tool that locates regions of recirculation in both steadyÙstate and transient soÙ lutions. Separation. It is desirable for transient simulaÙ tions to require only a single time slice of the field data. Needing
Exhaust gas recirculation for three-valve engine
S. Yagi; U. Asaka
An exhaust gas recirculation system is described for an internal combustion spark ignition piston engine having a main combustion chamber and an auxiliary combustion chamber connected by a restricted torch nozzle. A lean mixture is supplied to the main combustion chamber, and a rich mixture is supplied to the auxiliary combustion chamber. A conduit conducts a portion of the exhaust
A recirculating seawater aquarium system for inland laboratories
M. E. Lickey; R. L. Emigh; F. R. Randle
We have designed and installed a 7,500 l recirculating aquarium system for the purpose of maintaining marine gastropods in an inland laboratory. It is completely nonmetallic and can be adapted for any number of isolated living compartments. Vonvenient and efficient filtration is achieved by the use of disposable cartridge filters. The water temperature is regulated by a direct expansion cooling
Dynamic Scheduling of Internal Exhaust Gas Recirculation Systems.
Stefanopoulou, Anna
-fuel charge and lower the combustion temperature which reduces NOx feedgas emissions. Conventionally, exhaust gas recirculation. The dynamic sched- ule consists of a steady-state map of the camshaft timing- trogen (NOx) in internal combustion engines. The in- ert exhaust gases dilute the inducted air
A Low-Cost Recirculation System Using Disposable Beverage Containers
Mark C. Bates; Terrence R. Tiersch
A tank system with recirculating water designed for use with disposable plastic 3-L beverage bottles is described. The system consisted of 100 culture units (2-L working volume in each), five 40-L tanks, and an upwelling biofilter. The 40-L tanks were used to increase the total volume of the system, to allow operation of the filter when bottles were not occupied,
Digital feedwater and recirculation flow control for GPUN Oyster Creek
D. Burjorjee; B. Gan
This paper describes the digital system for feedwater and recirculation control that GPU Nuclear will be installing at Oyster Creek during its next outage - expected circa December 1992. The replacement was motivated by considerations of reliability and obsolescence - the analog equipment was aging and reaching the end of its useful life. The new system uses Atomic Energy of
Confined Turbulent Swirling Recirculating Flow Predictions. Ph.D. Thesis
NASA Technical Reports Server (NTRS)
Abujelala, M. T.
Turbulent swirling flow, the STARPIC computer code, turbulence modeling of turbulent flows, the k-xi turbulence model and extensions, turbulence parameters deduction from swirling confined flow measurements, extension of the k-xi to confined swirling recirculating flows, and general predictions for confined turbulent swirling flow are discussed.
Thermal Characterization Of An Amtec Recirculating Test Cell
M. L. Underwood; D. O'Connor; R. M. Williams; B. Jefflies-Nakamura; M. A. Ryan; C. P. Bankston
The Alka i Metal Thermoelectric Converter (AMTEC) recirculating test cell has been operated in order to determine the magnitudes of the primary heat losses of the cell and the value of the emissivity of the condenser surface. The energy balance included radiation losses, conductive losses, and losses due to the flow of sodium into the cell. The radiative heat flux
Phosphorus dynamics at multiple time scales in the pelagic zone of a large shallow lake in Florida, USA
Karl E. Havens; Kang-Ren Jin; Nenad Iricanin; R. Thomas James
Phosphorus (P) dynamics in large shallow lakes are greatly influenced by physical processes such as wind-driven sediment resuspension,\\u000a at times scales from hours to years. Results from long-term (30 year) research on Lake Okeechobee, Florida (area 1,730 km2, mean depth 2.7 m) illustrate key features of these P dynamics. Variations in wind velocity result in changes in water column\\u000a transparency,
Phosphorus dynamics at multiple time scales in the pelagic zone of a large shallow lake in Florida, USA
Karl E. Havens; Kang-Ren Jin; Nenad Iricanin; R. Thomas James
Phosphorus (P) dynamics in large shallow lakes are greatly influenced by physical processes such as wind-driven sediment resuspension,\\u000a at times scales from hours to years. Results from long-term (30 year) research on Lake Okeechobee, Florida (area 1,730 km2, mean depth 2.7 m) illustrate key features of these P dynamics. Variations in wind velocity result in changes in water column\\u000a transparency,
Holocene paleoseismicity, temporal clustering, and probabilities of future large (M > 7) earthquakes on the Wasatch fault zone, Utah
McCalpin, J.P.; Nishenko, S.P.
The chronology of M>7 paleoearthquakes on the central five segments of the Wasatch fault zone (WFZ) is one of the best dated in the world and contains 16 earthquakes in the past 5600 years with an average repeat time of 350 years. Repeat times for individual segments vary by a factor of 2, and range from about 1200 to 2600 years. Four of the central five segments ruptured between ??? 620??30 and 1230??60 calendar years B.P. The remaining segment (Brigham City segment) has not ruptured in the past 2120??100 years. Comparison of the WFZ space-time diagram of paleoearthquakes with synthetic paleoseismic histories indicates that the observed temporal clusters and gaps have about an equal probability (depending on model assumptions) of reflecting random coincidence as opposed to intersegment contagion. Regional seismicity suggests that for exposure times of 50 and 100 years, the probability for an earthquake of M>7 anywhere within the Wasatch Front region, based on a Poisson model, is 0.16 and 0.30, respectively. A fault-specific WFZ model predicts 50 and 100 year probabilities for a M>7 earthquake on the WFZ itself, based on a Poisson model, as 0.13 and 0.25, respectively. In contrast, segment-specific earthquake probabilities that assume quasi-periodic recurrence behavior on the Weber, Provo, and Nephi segments are less (0.01-0.07 in 100 years) than the regional or fault-specific estimates (0.25-0.30 in 100 years), due to the short elapsed times compared to average recurrence intervals on those segments. The Brigham City and Salt Lake City segments, however, have time-dependent probabilities that approach or exceed the regional and fault specific probabilities. For the Salt Lake City segment, these elevated probabilities are due to the elapsed time being approximately equal to the average late Holocene recurrence time. For the Brigham City segment, the elapsed time is significantly longer than the segment-specific late Holocene recurrence time.
Determination of cationic surfactants by capillary zone electrophoresis and micellar electrokinetic chromatography with deoxycholate micelles in the presence of large organic solvent concentrations.
Herrero-MartÚnez, J M; Simµ-Alfonso, E F; Mongay-FernÃndez, C; Ramis-Ramos, G
Mixtures of the cationic surfactants benzalkonium chloride (BKC) and cetylpyridinium chloride (CPC) were quickly resolved and reproducibly and reliably determined by using background electrolytes (BGEs) containing 80 mM borate, pH 8.5, bile salts and large concentrations of an organic solvent. When the bile salt is present, the separation mechanism changes from capillary zone electrophoresis (CZE) to a mixed micellar electrokinetic chromatography (MEKC)-CZE, with predominant MEKC interactions, which lead to an excellent resolution of all the solutes, including the C12-C18 homologues of BKC and CPC. A BGE containing 50 mM sodium deoxycholate and 30% ethanol for an extreme resolution, or 20% tetrahydrofuran for an adequate resolution within a much shorter analysis time, is recommended. The procedure was applied to the determination of the surfactants in industrial and household formulations, with excellent resolution between the homologues, detection limits of a few microg ml(-1) and reproducibilities below 2%. PMID:11105866
Simulating Large-Scale Earthquake Dynamic Rupture Scenarios On Natural Fault Zones Using the ADER-DG Method
NASA Astrophysics Data System (ADS)
Gabriel, Alice; Pelties, Christian
In this presentation we will demonstrate the benefits of using modern numerical methods to support physic-based ground motion modeling and research. For this purpose, we utilize SeisSol an arbitrary high-order derivative Discontinuous Galerkin (ADER-DG) scheme to solve the spontaneous rupture problem with high-order accuracy in space and time using three-dimensional unstructured tetrahedral meshes. We recently verified the method in various advanced test cases of the 'SCEC/USGS Dynamic Earthquake Rupture Code Verification Exercise' benchmark suite, including branching and dipping fault systems, heterogeneous background stresses, bi-material faults and rate-and-state friction constitutive formulations. Now, we study the dynamic rupture process using 3D meshes of fault systems constructed from geological and geophysical constraints, such as high-resolution topography, 3D velocity models and fault geometries. Our starting point is a large scale earthquake dynamic rupture scenario based on the 1994 Northridge blind thrust event in Southern California. Starting from this well documented and extensively studied event, we intend to understand the ground-motion, including the relevant high frequency content, generated from complex fault systems and its variation arising from various physical constraints. For example, our results imply that the Northridge fault geometry favors a pulse-like rupture behavior.
A recirculating linac-based facility for ultrafast X-ray science
Corlett, J.N; Barletta, W.A.; DeSantis, S.; Doolittle, L.; Fawley, W.M.; Green, M.A.; Heimann, P.; Leone, S.; Lidia, S.; Li, D.; Ratti, A.; Robinson, K.; Schoenlein, R.; Staples, J.; Wan, W.; Wells, R.; Wolski, A.; Zholents, A.; Placidi, M.; Pirkl, W.; Parmigiani, F.
We present an updated design for a proposed source of ultra-fast synchrotron radiation pulses based on a recirculating superconducting linac, in particular the incorporation of EUV and soft x-ray production. The project has been named LUX - Linac-based Ultrafast X-ray facility. The source produces intense x-ray pulses with duration of 10-100 fs at a 10 kHz repetition rate, with synchronization of 10 s fs, optimized for the study of ultra-fast dynamics. The photon range covers the EUV to hard x-ray spectrum by use of seeded harmonic generation in undulators, and a specialized technique for ultra-short-pulse photon production in the 1-10 keV range. High-brightness rf photocathodes produce electron bunches which are optimized either for coherent emission in free-electron lasers, or to provide a large x/y emittance ration and small vertical emittance which allows for manipulation to produce short-pulse hard x-rays. An injector linac accelerates the beam to 120 MeV, and is followed by four passes through a 600-720 MeV recirculating linac. We outline the major technical components of the proposed facility.
A Recirculating Linac-Based Facility for Ultrafast X-Ray Science
J. N. Corlett; W. A. Barletta; S. DeSantis; L. Doolittle; W. M. Fawley; M.A. Green; P. Heimann; S. Leone; S. Lidia; D. Li; A. Ratti; K. Robinson; R. Schoenlein; J. Staples; W. Wan; R. Wells; A.Wolski; A. Zholents; F. Parmigiani; M. Placidi; W. Pirkl; R. A. Rimmer; S. Wang
We present an updated design for a proposed source of ultra-fast synchrotron radiation pulses based on a recirculating superconducting linac [1,2], in particular the incorporation of EUV and soft x-ray production. The project has been named LUX--Linac-based Ultrafast X-ray facility. The source produces intense x-ray pulses with duration of 10-100 fs at a 10 kHz repetition rate, with synchronization of 10's fs, optimized for the study of ultra-fast dynamics. The photon range covers the EUV to hard x-ray spectrum by use of seeded harmonic generation in undulators, and a specialized technique for ultra-short pulse photon production in the 1-10 keV range. High brightness rf photocathodes produce electron bunches which are optimized either for coherent emission in free electron lasers, or to provide a large x/y emittance ration and small vertical emittance which allows for manipulation to produce short-pulse hard x-rays. An injector linac accelerates the beam to 120 MeV, and is followed by f our passes through a 600-720 MeV recirculating linac. We outline the major technical components of the proposed facility.
Digital feedwater and recirculation flow control for GPUN Oyster Creek
Burjorjee, D. (Atomic Energy of Canada Ltd., Mississauga, Ontario (Canada)); Gan, B. (GPU Nuclear Corp., Parsippany, NJ (United States))
This paper describes the digital system for feedwater and recirculation control that GPU Nuclear will be installing at Oyster Creek during its next outage - expected circa December 1992. The replacement was motivated by considerations of reliability and obsolescence - the analog equipment was aging and reaching the end of its useful life. The new system uses Atomic Energy of Canada Ltd.'s software platform running on dual, redundant, industrial-grade 386 computers with opto-isolated field input/output (I/O) accessed through a parallel bus. The feedwater controller controls three main feed regulating valves, two low flow regulating valves, and two block valves. The recirculation controller drives the five scoop positioners of the hydraulic couplers. The system also drives contacts that lock up the actuators on detecting an open circuit in their current loops.
Research on leachate recirculation from different types of landfills
Wang Qi [Research Institute of Solid Waste Management, Chinese Research Academy of Environmental Sciences, No. 8 of Dayangfang, Chaoyang District, Beijing 100012 (China) and Faculty of Engineering, Fukuoka University, 8-19-1 Nanakuma, Johnan-ku, Fukuoka 814-0180 (Japan)]. E-mail: email@example.com; Matsufuji, Yasushi [Faculty of Engineering, Fukuoka University, 8-19-1 Nanakuma, Johnan-ku, Fukuoka 814-0180 (Japan); Dong Lu [Research Institute of Solid Waste Management, Chinese Research Academy of Environmental Sciences, No. 8 of Dayangfang, Chaoyang District, Beijing 100012 (China); Huang Qifei [Research Institute of Solid Waste Management, Chinese Research Academy of Environmental Sciences, No. 8 of Dayangfang, Chaoyang District, Beijing 100012 (China); Hirano, Fumiaki [Faculty of Engineering, Fukuoka University, 8-19-1 Nanakuma, Johnan-ku, Fukuoka 814-0180 (Japan); Tanaka, Ayako [Faculty of Engineering, Fukuoka University, 8-19-1 Nanakuma, Johnan-ku, Fukuoka 814-0180 (Japan)
Landfills can produce a great amount of leachate containing highly concentrated organic matter. This is especially true for the initial leachate from landfilled municipal solid wastes (MSW) that generally has concentrations of COD{sub Cr} and BOD{sub 5} up to 80,000 and 50,000 mg/L, respectively. The leachate could be disposed by means of recirculating technique, which decomposes the organics through the action of proliferating microorganisms and thereby purifies the leachate, and simultaneously accelerates organic decomposition through water saturation control. Data from experimental results indicated that leachate recirculating could reduce the organic concentration considerably, with a maximum reduction rate of COD{sub Cr} over 95%; and, using a semi-aerobic process, NH{sub 3}-N concentration of treated leachate could be under 10 mg/L. In addition, the organic concentration in MSW decreased greatly.
Ammonia Conversion Characteristics in a Closed Recirculating Aquaculture System
Guang-Yu Wang; Ji-xian Yang; Fang Ma; Lei Chen; Wei-Guo Li; Jingbo Guo
Nitrification and denitrification were commonly used in the recirculating aquaculture system (RAS) to decrease the ammonia and nitrate concentration. The variation characteristics of nitrogenous compounds and microbiology in a closed RAS were studied with gradually increasing ammonia-nitrogen (NH4 +-N) concentration. The NH4 +-N was completely converted into nitrite nitrogen (NO2 --N) in 46 days, but the NO2 --N raised slowly
Growth Performance of Walleye, Sander vitreus, in Recirculating Aquaculture Systems
Chester B. Zarnoch; Martin P. Schreibman; Richard T. Colesante; Michael B. Timmons
Walleye, Sander vitreus, fingerlings were reared in two recirculating aquaculture systems (RAS) to compare growth performance at three stocking densities (11, 24, and 36 kg\\/m). There was a negative relationship between increasing stocking density and growth calculated as percent body weight (BW) gain\\/day, total length (mm) gain\\/day, specific growth rate (SGR) of weight (%\\/day), and SGR of total length (%\\/day).
Steering algorithms for a small recirculating heavy-ion accelerator
Sharp, W.M.; Grote, D.P.; Hemandez, G.W.
Beam-steering algorithms are proposed for a small recirculating induction accelerator being built at the Lawrence Livermore National Laboratory. The principal problem is that the transverse position and velocity of the beam must be inferred from capacitive position monitors, and this determination is complicated by the limited probe resolution and by the lattice errors within steering modules. The fluid/envelope code CIRCE is used to evaluate these algorithms.
Mathematical modeling of leachate routing in a leachate recirculating landfill
Philip T McCreanor; Debra R Reinhart
Full-scale application of leachate recirculation has been hampered by an inability to uniformly apply leachate to the waste mass. Much of this problem is due to the varied nature of the disposed waste which promotes preferential routing and short-circuiting of leachate flows. The United States Geological Surveys Saturated-Unsaturated Flow and Transport (SUTRA) model [Voss C. I. (1984) SUTRA, SaturatedUnsaturated Transport,
Analysis of Hatch2 dual recirculation pump trip startup test
A. Alapour; R. A. Hommerson
A dual recirculation pump trip (2-RPT) test, conducted as a part of the Edwin I. Hatch Nuclear Plant Unit 2 (Hatch-2) startup testing, is analyzed using onedimensional reactor kinetics and point reactor kinetics options in RETRAN-02 MOD002. The nuclear data utilized in RETRAN are obtained by SIMTRAN using the three-dimensional core simulator solution by SIMULATE (RTS\\/7), taking into account exposure
AMTEC recirculating test cell component testing and operation
M. L. Underwood; R. K. Sievers; D. O'Connor; R. M. Williams; B. Jeffries-Nakamura; C. P. Bankston
Alkali metal thermoelectric converter operation in a recirculating test cell (RTC), which requires a small electromagnetic pump (EM) and a high-temperature beta-double-prime alumina-solid-electrolyte (BASE)-to-metal seal, is discussed. The design of a pump and an active metal braze seal and the initial operation of a cell using these components are described. The pump delivered 0.25 cu cm\\/min against a 28-psia head.
Industrial oven having air recirculating means for minimizing heat loss
Nowack, W.C.
An industrial oven is described in which articles to be heat treated are carried by a conveyor through a heated tunnel space in a tunnel structure which has end walls with access openings, such oven comprising a nozzle directed downwardly into the tunnel space at an inclined angle across at least one access opening, an exhaust opening communicating with the tunnel space in the vicinity of the upper portion of such access opening, and air handling means for withdrawing hot air from the tunnel space through said exhaust opening while blowing hot air into the tunnel space through said nozzle for minimizing the escape of hot air through such access opening. The air handling means may take the form of a recirculating blower connected between the exhaust opening and the nozzle. The oven may have an air heating and recirculating system which withdraws air from the tunnel space. Instead of providing a separate recirculating blower, exhaust and supply ducts may be connected to the intake and discharge sides of such system and may extend to the exhaust opening and the nozzle to circulate hot air out of the tunnel space through the exhaust opening and into the tunnel space through the nozzle.
Cyclone reactor with internal separation and axial recirculation
Becker, Frederick E. (Reading, MA); Smolensky, Leo A. (Concord, MA)
A cyclone combustor apparatus contains a circular partition plate containing a central circular aperture. The partition plate divides the apparatus into a cylindrical precombustor chamber and a combustor chamber. A coal-water slurry is passed axially into the inlet end of the precombustor chamber, and primary air is passed tangentially into said chamber to establish a cyclonic air flow. Combustion products pass through the partition plate aperture and into the combustor chamber. Secondary air may also be passed tangentially into the combustor chamber adjacent the partition plate to maintain the cyclonic flow. Flue gas is passed axially out of the combustor chamber at the outlet end and ash is withdrawn tangentially from the combuston chamber at the outlet end. A first mixture of flue gas and ash may be tangentially withdrawn from the combustor chamber at the outlet end and recirculated to the axial inlet of the precombustor chamber with the coal-water slurry. A second mixture of flue gas and ash may be tangentially withdrawn from the outlet end of the combustor chamber and passed to a heat exchanger for cooling. Cooled second mixture is then recirculated to the axial inlet of the precombustor chamber. In another embodiment a single cyclone combustor chamber is provided with both the recirculation streams of the first mixture and the second mixture.
Demonstration of a Highly Efficient Solid Oxide Fuel Cell Power System Using Adiabatic Steam Reforming and Anode Gas Recirculation
Powell, Michael R.; Meinhardt, Kerry D.; Sprenkle, Vincent L.; Chick, Lawrence A.; Mcvay, Gary L.
Solid oxide fuel cells (SOFC) are currently being developed for a wide variety of applications because of their high efficiency at multiple power levels. Applications for SOFCs encompass a large range of power levels including 1-2 kW residential combined heat and power applications, 100-250 kW sized systems for distributed generation and grid extension, and MW-scale power plants utilizing coal. This paper reports on the development of a highly efficient, small-scale SOFC power system operating on methane. The system uses adiabatic steam reforming of methane and anode gas recirculation to achieve high net electrical efficiency. The anode exit gas is recirculated and all of the heat and water required for the endothermic reforming reaction are provided by the anode gas emerging from the SOFC stack. Although the single-pass fuel utilization is only about 55%, because of the anode gas recirculation the overall fuel utilization is up to 93%. The demonstrated system achieved gross power output of 1650 to 2150 watts with a maximum net LHV efficiency of 56.7% at 1720 watts. Overall system efficiency could be further improved to over 60% with use of properly sized blowers.
Investigation of groundwater recirculation for the removal of RDX from the Pantex Plant perched aquifer
Woods, A.L. [ed.; Barnes, D.L. [Amarillo National Resource Center for Plutonium, TX (United States); Boles, K.M.; Charbeneau, R.J. [Univ. of Texas, Austin, TX (United States); Black, S.; Rainwater, K. [Texas Tech Univ., Lubbock, TX (United States). Water Resources Center
The Pantex Plant near Amarillo, Texas, is a US Department of Energy (DOE) facility that has been in operation since 1942. Past and present operations at Pantex include the creation of chemical high explosives components for nuclear weapons and assembly and disassembly of nuclear weapons. The Pantex Plant is underlain by the Ogallala aquifer, which in this area, consists of the main water-bearing unit and a perched water zone. These are separated by a fine-grained zone of low permeability. Multiple contaminant plumes containing high explosive (HE) compounds have been detected in the perched aquifer beneath the plant. The occurrence of these contaminants is the result of past waste disposal practices at the facility. RDX is an HE compound, which has been detected in the groundwater of the perched aquifer at significant concentrations. A pilot-scale, dual-phase extraction treatment system has been installed at one location at the plant, east of Zone 12, to test the effectiveness of such a system on the removal of these contaminants from the subsurface. A tracer test using a conservative tracer, bromide (Br), was conducted at the treatment site in 1996. In addition to the bromide, RDX and water elevations in the aquifer were monitored. Using data from the tracer test and other relevant data from the investigations at Pantex, flow and contaminant transport in the perched aquifer were simulated with groundwater models. The flow was modeled using MODFLOW and the transport of contaminants in the aqueous phase was modeled using MT3D. Modeling the perched aquifer had been conducted to characterize the flow in the perched aquifer; estimate RDX retardation in the perched aquifer; and evaluate the use of groundwater re-circulation to enhance the extraction of RDX from the perched aquifer.
Inactivation of bacteria using ultraviolet irradiation in a recirculating salmonid culture system
Mark J. Sharrer; Steven T. Summerfelt; Graham L. Bullock; Lauren E. Gleason; Jessica Taeuber
The objective of this research was to determine the ultraviolet (UV) irradiation dosages required to inactivate bacteria in a commercial-scale recirculating salmonid culture system. Research was conducted in the commercial-scale recirculating system used for Arctic char growout at the Conservation Fund Freshwater Institute (Shepherdstown, West Virginia). This recirculating system uses a UV channel unit to treat 100% of the 4750L\\/min
Ventilating characteristics of a recirculating air-curtain laboratory exhaust hood
Janes, Dale Floyd
and Advantages REFERENCES . . . . . . . ~ . ~ ~ ~ APPENDIX A ? ILLUSTRATIONS OF SMOKE TESTS ON A RECIRCULATING AIR-CURTAIN LABORATORY EXHAUST HOOD . APPENDIX 8 - ENERGY SAVINGS CALCULATIONS FOR A RECIRCULATING AIR-CURTAIN LABORATORY EXHAUST HOOD . APPENDIX...VENTILATING CHARACTERISTICS OF A RECIRCULATING AIR-CURTAIN LABORATORY EXHAUST HOOD A Thesis by DALE FLOYD JANES Submitted to the Graduate College of Texas A8M University in partial fulfillment of the requirement for the degree of MASTER...
Modelling non-volcanic tremor, slow slip events and large earthquakes in the Guerrero subduction zone (Mexico) with space-variable frictional weakening and creep
NASA Astrophysics Data System (ADS)
Zigone, Dimitri; Ben-Zion, Yehuda; Campillo, Michel
We explore with numerical simulations basic physical conditions leading to key observed features of non-volcanic tremor (NVT) in relation to slow slip events (SSEs) and earthquakes along the Guerrero segment of the Mexican subduction zone. To study the interactions between different modes of slip, and examine possible variations over timescales larger than the 15 year observational interval, we use a model with a planar interface governed by space-varying static/kinetic friction and dislocation creep in a 3-D elastic solid. A fault section with zero weakening during frictional slip fails in a mode corresponding to a `critical depinning transition' that produces generically many observed features of NVT. A patch with elevated creep coefficients represents a section with SSE. Simulations with small added stress oscillations are used to examine triggering of NVT by large remote earthquakes. The results reproduce well the basic observed properties of NVT and SSE in the Guerrero area, while pointing to complex interactions between large earthquake cycles, quasi-period SSE and scale-invariant NVT behaviour. The model simulations provide additional information on expected frequency-magnitude statistics, slip distributions and space-time properties of the different event types that may be tested with accumulation of future data. Some earthquake and NVT events near the opposite sides of the SSE patch have significant separation between their hypocentres and centroids. The rates of these events are correlated with the creep evolution in the SSE section. The results also suggest that aseismic deformation in the area may have transients on timescales larger than the observational period.
Holocene behavior of the Brigham City segment: implications for forecasting the next large-magnitude earthquake on the Wasatch fault zone, Utah
Personius, Stephen F.; DuRoss, Christopher B.; Crone, Anthony J.
The Brigham City segment (BCS), the northernmost Holocene?active segment of the Wasatch fault zone (WFZ), is considered a likely location for the next big earthquake in northern Utah. We refine the timing of the last four surface?rupturing (~Mw 7) earthquakes at several sites near Brigham City (BE1, 2430Ý250; BE2, 3490Ý180; BE3, 4510Ý530; and BE4, 5610Ý650 cal yr B.P.) and calculate mean recurrence intervals (10601500??yr) that are greatly exceeded by the elapsed time (~2500??yr) since the most recent surface?rupturing earthquake (MRE). An additional rupture observed at the Pearsons Canyon site (PC1, 1240Ý50 cal yr B.P.) near the southern segment boundary is probably spillover rupture from a large earthquake on the adjacent Weber segment. Our seismic moment calculations show that the PC1 rupture reduced accumulated moment on the BCS about 22%, a value that may have been enough to postpone the next large earthquake. However, our calculations suggest that the segment currently has accumulated more than twice the moment accumulated in the three previous earthquake cycles, so we suspect that additional interactions with the adjacent Weber segment contributed to the long elapse time since the MRE on the BCS. Our moment calculations indicate that the next earthquake is not only overdue, but could be larger than the previous four earthquakes. Displacement data show higher rates of latest Quaternary slip (~1.3??mm/yr) along the southern two?thirds of the segment. The northern third likely has experienced fewer or smaller ruptures, which suggests to us that most earthquakes initiate at the southern segment boundary.
Recirculation-aeration: Bibliography for aquaculture. Bibliographies and literature of agriculture (Final)
Perschbacher, P.W.; Powell, R.V.; Freeman, D.W.; Lorio, W.J.; Hanfman, D.T.
The bibliography includes literature citations through 1992 related to water recirculation and aeration in aquaculture. The focus is on filtration, aeration, and circulation techniques in various aquaculture situations.
On part load recirculation of pumps and fans-a generic study
NASA Astrophysics Data System (ADS)
Stapp, D.; Pelz, P. F.; Loens, J. M.
At part load in turbo machinery, there is a boundary layer separation resulting in a large vortex structure called part load recirculation. Up to now the influence of Reynolds number, relative roughness and degree of turbulence on this important stability limit of machines is not sufficiently understood. To shed some light onto these phenomena, in this work the simplest "machine" is considered by numerical and experimental studies. The apparatus we examine is a circular pipe at rest followed by a rotating co-axial pipe segment. By doing so, we have a generic test case which serves to study the critical flow number, defined by the onset of the separation and formation of a ring vortex.
Superconcentration of photospheric sources of the large-scale open solar magnetic field in the main zone of active longitudes, differential rotation blocking, and origination of the four-sector structure. 1. The field and solar activity dynamics
NASA Astrophysics Data System (ADS)
Ivanov, K. G.
The phenomena of superconcentration of the large-scale field photospheric sources in the main zone of active longitudes, blocking of regular differential rotation by these sources, and origination of the four-sector structure of the solar magnetic field during the decline phase of cycle 23 have been considered in more detail and taking into account the polar correction. It has been indicated that superconcentration was formed due to the penetration of photospheric sources into the zone from the western surroundings of this zone and owing to the generation of the large-scale field in the zone itself. The dynamics of a blocking-induced complex MHD disturbance with reflected from the zone and reconnecting photospheric sources of negative and positive polarity, respectively, and the transformation of the bisector structure into the four-sector one have been considered. It has been indicated that the dynamics of this MHD disturbance was responsible for that of associated solar activity: the generation of sunspot groups, appearance of flares, and, finally, origination of a powerful heliospheric storm and the solar-terrestrial extrastorm of July 22-27, 2004.
Lymphopoiesis and lymphocyte recirculation in the sheep fetus
The production and the circulation of lymphocytes has been examined in the sheep fetus where neither foreign antigen nor immunoglobulins occur. It was found that as the lymphoid organs increased in size during fetal life, the numbers and the output of lymphocytes in the thoracic duct lymph increased. The recirculating pool of lymphocytes was estimated to be 5.5 +/- 1.5 X 10(8) cells in fetal lambs 95-100 days of age, 5.7 +/- 1.2 X 10(9) cells in fetuses 130-135 days of age, and 1.2 +/0 9.3 X 10(10) cells in fetuses near to term. The rate of addition of lymphocytes to the recirculating pool was 3.2 +/- 1.9 X 10(6) cells/h in fetuses of 100 days and 3.4 +/- 0.9 X 10(7) cells/h in fetuses of 130 days of age. Lymphocytes recirculated from blood to lymph in fetuses; labeled cells injected into the blood stream reappeared in the thoracic duct lymph promptly and reached maximum levels around 12-18 h after they were injected. Labeled lymphocytes were detected subsequently in greatest numbers in the lymph nodes, particularly in the mesenteric lymph nodes and in the interfollicular areas of the Peyer's patches. Chronic drainage of thoracic duct lymph from fetuses in utero for periods of up to 36 days had no obvious effects on the growth or development of the fetus and only minimal effects on the content of lymphocytes in the various lymphoid tissues even though the number of cells in the blood and lymph were reduced to between 20-30% of normal levels. Thymectomy done in fetuses about 2 mo befor cannulation of the thoracic duct reduced the output of cells in the thoracic duct to about 25% of normal levels and caused a significant reduction in the content of lymphocytes in the various lymphoid tissues. Thymectomized fetal lambs subjected to thoracic duct drainage for periods up to 2 wk in utero had a similar complement of lymphocytes in their lymphoid tissues to intact thymectomized fetal lambs. Lymphocytes obtained from the thoracic duct lymph of lambs thymectomized 2 mo previously recirculated from blood to lymph when they were injected intravenously, although they did this at a significantly slower rate than did lymphocytes from normal lambs. PMID:1244417
Central recirculation zone analysis in an unconfined tangential swirl burner with varying degrees of premixing
A. Valera-Medina; N. Syred; P. Kay; A. Griffiths
Swirl-stabilised combustion is one of the most widely used techniques for flame stabilisation, uses ranging from gas turbine\\u000a combustors to pulverised coal-fired power stations. In gas turbines, lean premixed systems are of especial importance, giving\\u000a the ability to produce low NOx systems coupled with wide stability limits. The common element is the swirl burner, which depends\\u000a on the generation of
High-resolution mapping of two large-scale transpressional fault zones in the California Continental Borderland: Santa Cruz-Catalina Ridge and Ferrelo faults
NASA Astrophysics Data System (ADS)
Legg, Mark R.; Kohler, Monica D.; Shintaku, Natsumi; Weeraratne, Dayanthie S.
New mapping of two active transpressional fault zones in the California Continental Borderland, the Santa Cruz-Catalina Ridge fault and the Ferrelo fault, was carried out to characterize their geometries, using over 4500 line-km of new multibeam bathymetry data collected in 2010 combined with existing data. Faults identified from seafloor morphology were verified in the subsurface using existing seismic reflection data including single-channel and multichannel seismic profiles compiled over the past three decades. The two fault systems are parallel and are capable of large lateral offsets and reverse slip during earthquakes. The geometry of the fault systems shows evidence of multiple segments that could experience throughgoing rupture over distances exceeding 100 km. Published earthquake hypocenters from regional seismicity studies further define the lateral and depth extent of the historic fault ruptures. Historical and recent focal mechanisms obtained from first-motion and moment tensor studies confirm regional strain partitioning dominated by right slip on major throughgoing faults with reverse-oblique mechanisms on adjacent structures. Transpression on west and northwest trending structures persists as far as 270 km south of the Transverse Ranges; extension persists in the southern Borderland. A logjam model describes the tectonic evolution of crustal blocks bounded by strike-slip and reverse faults which are restrained from northwest displacement by the Transverse Ranges and the southern San Andreas fault big bend. Because of their potential for dip-slip rupture, the faults may also be capable of generating local tsunamis that would impact Southern California coastlines, including populated regions in the Channel Islands.
Passive mode control in the recirculating planar magnetron
Franzi, Matthew; Gilgenbach, Ronald; Lau, Y. Y.; Greening, Geoff; Zhang, Peng [Plasma, Pulsed Power, and Microwave Laboratory, Nuclear Engineering and Radiological Sciences Department, University of Michigan, Ann Arbor, Michigan 48109-2104 (United States); Hoff, Brad [Air Force Research Laboratory, Kirtland AFB, New Mexico 87117 (United States)
Preliminary experiments of the recirculating planar magnetron microwave source have demonstrated that the device oscillates but is susceptible to intense mode competition due, in part, to poor coupling of RF fields between the two planar oscillators. A novel method of improving the cross-oscillator coupling has been simulated in the periodically slotted mode control cathode (MCC). The MCC, as opposed to a solid conductor, is designed to electromagnetically couple both planar oscillators by allowing for the propagation of RF fields and electrons through resonantly tuned gaps in the cathode. Using the MCC, a 12-cavity anode block with a simulated 1 GHz and 0.26 c phase velocity (where c is the speed of light) was able to achieve in-phase oscillations between the two sides of the device in as little as 30 ns. An analytic study of the modified resonant structure predicts the MCC's ability to direct the RF fields to provide tunable mode separation in the recirculating planar magnetron. The self-consistent solution is presented for both the degenerate even (in phase) and odd (180 Degree-Sign out of phase) modes that exist due to the twofold symmetry of the planar magnetrons.
Continuous hydroponic wheat production using a recirculating system
NASA Technical Reports Server (NTRS)
Mackowiak, C. L.; Owens, L. P.; Hinkle, C. R.; Prince, R. P.
Continuous crop production, where plants of various ages are growing simultaneously in a single recirculating nutrient solution, is a possible alternative to batch production in a Controlled Ecological Life Support System. A study was conducted at John F. Kennedy Space Center where 8 trays (0.24 sq m per tray) of Triticum aestivum L. Yecora Rojo were grown simultaneously in a growth chamber at 23 C, 65 percent relative humidity, 1000 ppm CO2, continuous light, with a continuous flow, thin film nutrient delivery system. The same modified Hoagland nutrient solution was recirculated through the plant trays from an 80 L reservoir throughout the study. It was maintained by periodic addition of water and nutrients based on chemical analyses of the solution. The study was conducted for 216 days, during which 24 trays of wheat were consecutively planted (one every 9 days), 16 of which were grown to maturity and harvested. The remaining 8 trays were harvested on day 216. Grain yields averaged 520 g m(exp -2), and had an average edible biomass of 32 percent. Consecutive yields were unaffected by nutrient solution age. It was concluded that continual wheat production will work in this system over an extended period of time. Certain micronutrient deficiencies and toxicities posed problems and must be addressed in future continuous production systems.
Self-Recirculating Casing Treatment Concept for Enhanced Compressor Performance
NASA Technical Reports Server (NTRS)
Hathaway, Michael D.
A state-of-the-art CFD code (APNASA) was employed in a computationally based investigation of the impact of casing bleed and injection on the stability and performance of a moderate speed fan rotor wherein the stalling mass flow is controlled by tip flow field breakdown. The investigation was guided by observed trends in endwall flow characteristics (e.g., increasing endwall aerodynamic blockage) as stall is approached and based on the hypothesis that application of bleed or injection can mitigate these trends. The "best" bleed and injection configurations were then combined to yield a self-recirculating casing treatment concept. The results of this investigation yielded: 1) identification of the fluid mechanisms which precipitate stall of tip critical blade rows, and 2) an approach to recirculated casing treatment which results in increased compressor stall range with minimal or no loss in efficiency. Subsequent application of this approach to a high speed transonic rotor successfully yielded significant improvements in stall range with no loss in compressor efficiency.
Impact of various leachate recirculation regimes on municipal solid waste degradation
Irem an; Turgut T. Onay
Landfilled municipal solid waste can be treated by introducing leachate into the waste matrix. Increasing attention is being given to landfill leachate recirculation as a means for in situ leachate treatment and landfill stabilization. Landfills with leachate recirculation may be operated as municipal solid waste bioreactor treatment system rather than as a conventional waste dumping sites. In order to study
Developments in recirculating systems for Arctic char culture in North America
Steven T. Summerfelt; Gary Wilton; David Roberts; Tina Rimmerd; Kari Fonkalsrud
Arctic char (Salvelinus alpinus) tolerate high-density culture conditions, have an excellent fillet yield, are amenable to niche marketing, and are suitable for production within super-intensive recirculating systems. Much of the North American production of Arctic char has been within recirculating systems, which can provide more optimum water temperatures for fish growth and can also overcome limitations created by a lack
Oscar Zelaya; Claude E. Boyd; David R. Teichert-Coddington; Bartholomew W. Green
There is considerable interest in reducing negative environmental impacts of shrimp and fish farming. One of the most promising methods for reducing the environmental effects of pond aquaculture is to use water-recirculating systems to minimize effluents. However, few studies have been performed to evaluate the effect of recirculation upon soil and water quality in ponds. This study evaluates changes in
The potential use of constructed wetlands in a recirculating aquaculture system for shrimp culture
Ying-Feng Lin; Shuh-Ren Jing; Der-Yuan Lee
A pilot-scale constructed wetland unit, consisting of free water surface (FWS) and subsurface flow (SF) constructed wetlands arranged in series, was integrated into an outdoor recirculating aquaculture system (RAS) for culturing Pacific white shrimp (Litopenaeus vannamei). This study evaluated the performance of the wetland unit in treating the recirculating wastewater and examined the effect of improvement in water quality of
Performance Evaluation of a Router with Tunable Recirculating Buffers in an Optical Burst Switching Environment
Touch, Joe
Performance Evaluation of a Router with Tunable Recirculating Buffers in an Optical Burst Switching burst switching, recirculation, fiber delay lines, optical buffering. 1. Introduction Optical Burst fiber delay lines (FDL). There have been several studies in the past that have tried to evaluate optical
Recirculation injection by nonlinear gating for high-power laser pulses
Igor Jovanovic; Miro Shverdin; David Gibson; Curtis Brown
The average power and efficiency of processes that exhibit low interaction cross section and low optical loss can often be enhanced by recirculating the laser pulse in the cavity. Inverse Compton scattering of the photon pulse on an electron bunch, harmonic generation, and spectroscopy represent examples of such processes. Methods for laser recirculation that enhance the interaction efficiency have been
Unit process engineering for water quality control and biosecurity in marine water recirculating systems
Technology Transfer Automated Retrieval System (TEKTRAN)
High-intensity systems that treat and recirculate water must maintain a culture environment that can sustain near optimum fish health and growth at the design carrying capacity. Water recirculating systems that use centralized treatment systems can benefit from the economies of scale to decrease th...
Fish Health Management Considerations in Recirculating Aquaculture Systems -Part 2: Pathogens1
Watson, Craig A.
Cir 121 Fish Health Management Considerations in Recirculating Aquaculture Systems - Part 2 Aquaculture Laboratory, Ruskin FL 33570, Program in Fisheries and Aquatic Sciences, School of Forest Resources Introduction Recirculating aquaculture systems, also known as water reuse systems, have become more and more
Gold, Art
NITROGEN REMOVAL FOR ON-SITE SEWAGE DISPOSAL: A RECIRCULATING SAND FILTER/ROCK TANK DESIGN, C. G. McKiel ABSTRACT: The nitrogen removal abilities of recirculating sand filter/rock tank (RSF. The degree of total nitrogen removal was a function of both nitrification and denitrification. Nitrification
Membrane biological reactor treatment of a saline backwash flow from a recirculating aquaculture system
Mark J. Sharrer; Yossi Tal; Drew Ferrier; Joseph A. Hankins; Steven T. Summerfelt
A recirculating aquaculture system (RAS) can minimize water use, allowing fish production in regions where water is scarce and also placing the waterborne wastes into a concentrated and relatively small volume of effluent. The RAS effluent generated during clarifier backwash is usually small in volume (possibly 0.20.5% of the total recirculating flow when microscreen filters are used) but contains high
[Pilot scale research on impacts of leachate recirculation on its ultimate treatment].
Deng, Zhou; Jiang, Jian-guo; Huang, Zhong-lin; Feng, Xiang-ming; Zhou, Sheng-yong; Yang, Guo-dong
Two pilot scale simulated columns, with and without leachate recirculation, were erected to study impacts of leachate recirculation of traditional anaerobic bioreactor landfill on leachate ultimate treatment methods. The results indicate that recirculation can remove organic pollutants visibly, but it isn't effective to inbiodegradable components, nitrogen (N) and phosphorus (P) pollutants. After recircualted for 44 weeks, test column has a BODs removal ratio of 98.5%. BOD5/COD value of outflow is only 0.07. BOD5/TN and BOD5/TP are 0.13 and 11 respectively, which are much lower than the adequate value for anaerobic microorganisms. It's difficult to treat this kind of leachate by traditional biological methods. When a bioreactor landfill is being designed, leachate characteristics after recirculated should be well considered and adequate leachate treatment, landfill and recirculation schemes should be chosen to take full advantage of waste stack decontamination effects. PMID:16921969
[Effects of leachate recirculation volume on its characteristic and landfill stabilization rate].
Deng, Zhou; Jiang, Jian-Guo; Yang, Guo-Dong; Huang, Zhong-Lin; Feng, Xiang-Ming; Zhou, Sheng-Yong
Impacts of recirculation volume on leachate characteristic and landfill stabilization rate were studied. Four simulated bioreactor landfill columns were operated weekly with different recirculation ratios, respectively 5.3%, 2.7%, 0.67% leachate and 0.33% water, in this comparative research. The results indicate that simulated reactor with 5.3% recirculation ratio has the most rapidly stabilization rate and release the most organic pollutant. The shortest methane generation delay was also observed in this column. While simulated reactor with 2.7% recirculation ratio formed the best microbe environment and kept the highest reactor temperature 35 degrees C. It also had the best impactive load capacity and treating efficiency to leachate, and removal of COD was 77% and BOD5 was 88% respectively. In actual projects, appropriate leachate recirculation volume should be chosen according to design purpose of landfill sites. PMID:16599146
Distribution of Off-Flavor Compounds and Isolation of Geosmin-Producing Bacteria in a Series of Water Recirculating Systems for Rainbow Trout Culture
Kevin K. Schrader; Steven T. Summerfelt
Preharvest off-flavor in aquaculture products results in large economic losses to producers due to delayed harvest. The common off flavors earthy and musty are due to the presence of geosmin and 2-methylisoborneol (MIB), respectively. Although certain species of cyanobacteria are responsible for these problems in pond-cultured fish, the microbial sources of geosmin and MIB in recirculating aquaculture systems (RASs) are
Capture of CO2 From Recirculating Flue Gas Boilers
Ochs, Thomas L.
The possible need for an economical method for the separation of CO2 from flue gas adds a new set of challenges to power plant design, construction, operation, and maintenance. Many of the new requirements of CO2 separation are similar in nature to those addressed by the mature chemical engineering processes used in petroleum refining and industrial chemical production. Chemical engineering processes are regularly used to separate heterogeneous vapors in processes such as the fractionation of hydrocarbons or the separation of the components of air. This paper addresses the application of chemical engineering processes to the mixtures of gases and vapors found in the flue gas of recirculating boilers. Adaptation of these techniques can lead to a reduction in the energy required to capture CO2.
Energy stability in recirculating, energy-recovering linacs
Merminga, L.; Bisognano, J.J.; Delayen, J.R.
Recirculating, energy-recovering linacs can be used as driver accelerators for high power FELs. Instabilities which arise from fluctuations of the cavity fields are investigated. Energy changes can cause beam loss on apertures, or, when coupled to M{sub 56}, phase oscillations. Both effects change the beam induced voltage in the cavities and can lead to unstable variations of the accelerating field. Stability analysis for small perturbations from equilibrium is performed and threshold currents are determined. Furthermore, the analytical model is extended to include amplitude and phase feedback, with the transfer function in the feedback path presently modeled as a low-pass filter. The feedback gain and bandwidth required for stability are calculated for the high power UV FEL proposed for construction at CEBAF. 4 refs.
[Processing conditions of recirculated MBR for wastewater treatment].
L■, Hong; Xu, Youyi; Zhu, Baoku; Xu, Zhikang; Xie, Boming
In this paper, wastewater was treated with Recirculated Membrane Bio-Reactor (RMBR) and effluent quality became stable after four days running continuously. Critical membrane flux was increased with increasing crossflow velocity between 0.9-1.9 m/s. Under crossflow velocity of 1.9 m/s, critical membrane flux was enhanced from 72 L/(m2.h) to 76 L/(m2.h) or 81 L/(m2.h) respectively when powdered activated carbon (PAC) or both PAC and alum were added to the system. Between 22 degrees C-30 degrees C, the flux was elevated 1.9% per 1 degree C increased. Fouling materials were removed efficiently through cleaning physically or/and chemically with flux recovery of 47%-94%. PMID:12916204
Slawomir Bogacz, Vasiliy Morozov, Yves Roblin, Kevin Beard
Both Neutrino Factories (NF) and Muon Colliders (MC) require very rapid acceleration due to the short lifetime of muons. After a capture and bunching section, a linac raises the energy to about 900 MeV, and is followed by one or more Recirculating Linear Accelerators (RLA), possibly followed by a Rapid Cycling Synchnotron (RCS) or Fixed-Field Alternating Gradient (FFAG) ring. A RLA reuses the expensive RF linac section for a number of passes at the price of having to deal with different energies within the same linac. Various techniques including pulsed focusing quadruopoles, beta frequency beating, and multipass arcs have been investigated via simulations to improve the performance and reduce the cost of such RLAs.
SUPERFLIC: A recirculating superconducting linear collider toponium factory
Rosenzweig, J.B.
The conceptual design of a 0.3--0.4 TeV e{sup +}e{sup {minus}} linear collider which uses superconducting RF (SRF) accelerating cavities is presented. This machine is intended to provide high luminosity and low collision energy spread to allow precise studies of the t{bar t} resonant states. Only through use of SRF is such a collider made possible. It features use of recirculation arcs as a partial remedy to presently low SRF accelerating gradients. Development of this type of collider is motivated by and could serve as a stepping stone to exploiting SRF at higher energies. In TeV-range SRF colliders the serious difficulties arising from the beam-beam interaction, very small beam sizes and tolerances characteristic of normal conducting machines can be greatly diminished. 21 refs.
Recycling crop residues for use in recirculating hydroponic crop production
NASA Technical Reports Server (NTRS)
Mackowiak, C. L.; Garland, J. L.; Sager, J. C.
As part of bioregenerative life support feasibility testing by NASA, crop residues are being used to resupply elemental nutrients to recirculating hydroponic crop production systems. Methods for recovering nutrients from crop residues have evolved from water soaking (leaching) to rapid aerobic bioreactor processing. Leaching residues recovered the majority of elements but it also recovered significant amounts of soluble organics. The high organic content of leachates was detrimental to plant growth. Aerobic bioreactor processing reduced the organic content ten-fold, which reduced or eliminated phytotoxic effects. Wheat and potato production studies were successful using effluents from reactors having with 8- to 1-day retention times. Aerobic bioreactor effluents supplied at least half of the crops elemental mass needs in these studies. Descriptions of leachate and effluent mineral content, biomass productivity, microbial activity, and nutrient budgets for potato and wheat are presented.
TRACG Simulation of Drywell Gas Recirculation System in ESBWR
Cheung, Yee K.; Rao, Atambir S. [GE Nuclear Energy, 175 Curtner Avenue San Jose, California 95125 (United States)
This paper presents the results of a parametric study on the mitigating effects of the Drywell Gas Recirculation System (DGRS) in ESBWR during postulated LOCA and severe accidents. The post-accident containment pressure depends on the sum of the partial pressure from non-condensable gases and partial steam pressure inside the wet-well airspace. Results of parametric studies show that, with the activation of DGRS: (1) The containment pressure continues to reduce due to the redistribution of non-condensable gases from the wet-well back to the drywell; (2) The DGRS can be designed in a 'portable' fashion; (3) The Current ESBWR meets the design requirement with significant margin using only passive safety systems, and the margin increases considerably with the activation of DGRS. (authors)
Experiments With Recirculating Target for F-18 Production
NASA Astrophysics Data System (ADS)
Kiselev, M. Y.
Approximately 10 ml of O-18 water was loaded in an apparatus containing a 5 ml storage vessel, pump, silver target attached to a cyclotron, filter, backpressure regulator, conductivity meter, several valves and ion exchange cartridges. The water was continuously pumped through the target during proton bombardment at a rate 5 ml/min. Continuous irradiation with beam current ranging from 10 to 50 uA was conducted while pressure, temperature and conductivity were continuously monitored. The results indicate that recirculating of the target water can increase production of F-18 in relation to consumed O-18 water material. It can also increase productivity by eliminating idle periods for re-filling the target. A backpressure regulator can precisely control target pressure. This method also allows for continuous monitoring of the target material temperature, pressure, conductivity and accumulated radioactivity. Results of these observations provide important information about target performance and physical processes taking place inside the target.
Gray zones around diffuse large B cell lymphoma. Conclusions based on the workshop of the XIV meeting of the European Association for Hematopathology and the Society of Hematopathology in Bordeaux, France
Leticia Quintanilla-Martinez; Daphne de Jong; Antoine de Mascarel; Eric D. Hsi; Philip Kluin; Yaso Natkunam; Marie Parrens; Stefano Pileri; German Ott
The term gray-zone lymphoma has been used to denote a group of lymphomas with overlapping histological, biological, and\\u000a clinical features between various types of lymphomas. It has been used in the context of Hodgkin lymphomas (HL) and non-Hodgkin\\u000a lymphomas (NHL), including classical HL (CHL), and primary mediastinal large B cell lymphoma, cases with overlapping features\\u000a between nodular lymphocyte predominant Hodgkin
Oral bioavailability and enterohepatic recirculation of otilonium bromide in rats.
Shin, Beom Soo; Kim, Jung Jun; Kim, John; Hu, Sul Ki; Kim, Hyoung Jun; Hong, Seok Hyun; Kim, Han Kyung; Lee, Hye Suk; Yoo, Sun Dong
This study was conducted to examine the oral bioavailability and the possibility of enterohepatic recirculation of otilonium bromide in rats. A sensitive LC/MS/MS assay (LLOQ 0.5 ng/mL) was developed for the determination of otilonium and applied to i.v. and oral administration studies in bile duct cannulated (BDC) and non-BDC rats. After i.v. injection to BDC rats (1 mg/ kg as otilonium), average t(1/2), CL, Vz and AUC were 7.9 +/- 1.9 h, 8.7 +/- 3.1 mL/min/kg, 5.7 +/- 1.4 L/kg and 2,088 +/- 676 ng h/mL, respectively, and these values were comparable to those found in non-BDC rats. The percentages of i.v. dose excreted unchanged in bile and urine in BDC rats were 11.6 +/- 3.0 and 3.1 +/- 0.7%, respectively. Upon oral administration to non-BDC rats (20 mg/kg as otilonium), t(1/2), Cmax, Tmax and AUC were 6.4 +/- 1.3 h, 182.8 +/- 44.6 ng/mL, 1.9 +/- 1.6 h and 579 +/- 113 ng h/mL, respectively. The absolute oral bioavailability was low (1.1%), while the drug was preferentially distributed to gastrointestinal tissues. A secondary peak was observed in the serum concentration-time profiles in non-BDC rats following both i.v. and oral administration, indicating that otilonium bromide was subject to enterohepatic recirculation. PMID:18277617
Traffic and proliferative responses of recirculating lymphocytes in fetal calves.
Hein, W R; Shelton, J N; Simpson-Morgan, M W; Morris, B
The thoracic duct or efferent prescapular duct was cannulated in four fetal calves aged 121-259 days post-conception. The duration of lymph flow ranged from 2 to 20 days and the mean flow rates sustained over these collection periods varied from 5.4 to 48.8 ml/hr. Lymphocyte output ranged from 4.4 x 10(6) cells/hr in thoracic duct lymph from a 121-day fetus to 3.9 x 10(8) cells/hr in efferent prescapular lymph from a 259-day fetus. The circulating lymphocyte pool in fetal calves of about 120 and 190 days gestational age was calculated to contain, respectively, 4 x 10(8) cells and 2 x 10(10) cells. The proportion of lymphocytes bearing surface immunoglobulin detected in fetal lymph ranged from 2.1% to 8.7%. Recirculating lymphocytes from fetal calves produced strong proliferative responses when stimulated by T-cell mitogens but responded poorly to B-cell mitogens. Fetal lymphocytes also responded to stimulation by allogeneic cells and stimulated other cells to proliferate during mixed lymphocyte culture. When stimulated with Con A, fetal lymphocytes secreted IL-2 to a degree that was indistinguishable from the secretory behaviour of lymphocytes from adult animals. The results presented in this paper show that chronic lymphatic fistulae can be established successfully in fetal calves to give access to recirculating lymphocytes. This provides a new experimental approach for studying the development of the bovine immune system. PMID:2971606
Momentum and heat transfer in a complex recirculating flow
Rhee, H.S.
Three-dimensional and turbulent recirculating flows in enclosed spaces occur in many engineering situations. Accurate measurements of momentum- and heat-transfer characteristics are needed for direct engineering-design applications and for developments of numerical-simulation codes of these flows. A facility to generate recirculating flows driven by buoyancy and/or shear forces in a rectangular cavity was constructed to model such flows. Also, a visualization technique, involving temperature-sensitive liquid-crystal microcapsules, was developed to visualize the temperature and velocity fields simultaneously in any flow plane. Two flow cases were studied: (1) natural convection driven by buoyancy in a bottom-heated cavity, with Gr = 2.4 10/sup 7/, and (2) mixed-convection driven by shear force from a moving lid and buoyancy, with Gr = 2.4 x 10/sup 7/ and Re = 3200. In the mixed-convection case, Gr/Re/sup 2/ = 2.3, indicating that buoyancy and shear forces acting on the flow are comparable. In addition to the flow/temperature visualizations, measurements were made of velocity, temperature, and surface heat flux. Overall heat-transfer measurements were conducted for a wide range of the mixed-convection parameter, Gr/Re/sup 2/, in the cavity. Smooth transitions were found from natural convection to forced convection. The mixed convection regime was found in 0.5 < Gr/Re/sup 2/ < 80, the upper found of 80 being larger than that of flat plate data (about 10). This was probably due to heat-transfer enhancement by the TGL vortices.
The impact of full-scale leachate recirculation on leachate and gas characteristics
Reinhart, D.R. [Univ. of Central Florida, Orlando, FL (United States). Civil and Environmental Engineering Dept.; Al-Yousfi, A.B. [Union Carbide Corp., South Charleston, WV (United States)
Data from full-scale recirculating landfills were analyzed and compared with data from pilot and laboratory-scale investigations, and found to support conclusions drawn from tests, i.e., an acceleration of stabilization processes, leachate management opportunities, and enhancement of gas production can be expected during leachate recirculation. Leachate characteristics follow patterns observed in conventionally operated landfills, however degradation occurs at a faster rate. Leachate production rates are a function of landfill operations, climate, and recirculation rates. On-site storage is critical to leachate management and can dramatically reduce volume of leachate treated off-site.
NSDL National Science Digital Library
In the tradition of Yahooligans (reviewed in the March 22, 1996 Scout Report) and other so-called "green spaces," Lycos has created a new online safe haven for young users which is fairly self-contained, with the exception of the advertisements. (In response to criticisms regarding aggressive marketing to children at similar sites, Lycos claims that the ads are clearly marked and will not collect any personal information.) The site is composed of four sections: the Fun and Games Zone, the Homework Zone, the New and Cool Zone, and an area for parents and teachers. The first two sections are fairly deep, with numerous resources and activities aimed at various age levels. Some links in the Homework Zone lead users outside the site, but they are first presented with a gateway page informing them that they are leaving and offering advice on not divulging personal information.
Kainen, Paul C.
Control of biological growth in recirculating cooling systems using treated secondary effluent as makeup water with monochloramine.
Chien, Shih-Hsiang; Chowdhury, Indranil; Hsieh, Ming-Kai; Li, Heng; Dzombak, David A; Vidic, Radisav D
Secondary-treated municipal wastewater, an abundant and widely distributed impaired water source, is a promising alternative water source for thermoelectric power plant cooling. However, excessive biological growth is a major challenge associated with wastewater reuse in cooling systems as it can interfere with normal system operation as well as enhance corrosion and scaling problems. Furthermore, possible emission of biological aerosols (e.g., Legionella pneumophila) with the cooling tower drift can lead to public health concerns within the zone of aerosol deposition. In this study, the effectiveness of pre-formed and in-situ-formed monochloramine was evaluated for its ability to control biological growth in recirculating cooling systems using secondary-treated municipal wastewater as the only makeup water source. Bench-scale studies were compared with pilot-scale studies for their ability to predict system behavior under realistic process conditions. Effectiveness of the continuous addition of pre-formed monochloramine and monochloramine formed in-situ through the reaction of free chlorine with ammonia in the incoming water was evaluated in terms of biocide residual and its ability to control both planktonic and sessile microbial populations. Results revealed that monochloramine can effectively control biofouling in cooling systems employing secondary-treated municipal wastewater and has advantages relative to use of free chlorine, but that bench-scale studies seriously underestimate biocide dose and residual requirements for proper control of biological growth in full-scale systems. Pre-formed monochloramine offered longer residence time and more reliable performance than in-situ-formed monochloramine due to highly variable ammonia concentration in the recirculating water caused by ammonia stripping in the cooling tower. Pilot-scale tests revealed that much lower dosing rate was required to maintain similar total chlorine residual when pre-formed monochloramine was used as compared to in-situ-formed monochloramine. Adjustment of biocide dose to maintain monochloramine residual above 3mg/L is needed to achieve successful biological growth control in recirculating cooling systems using secondary-treated municipal effluent as the only source of makeup water. PMID:23063442
Evidence for baroclinic instability in the Gulf Stream recirculation
NASA Astrophysics Data System (ADS)
Hogg, Nelson G.
Long term current measurements from Polymode Array 2 are analyzed using the technique of empirical orthogonal functions applied in the frequency domain. The region of especially good instrument coverage and clearest decomposition into empirical modes is also in the Gulf Stream recirculation (? 36¯N 55¯W). On theoretical grounds, this is expected to be an area actively unstable to baroclinic disturbances ( GILL, GREEN and SIMMONS, 1974). Both the horizontal and vertical structure of motions with periods ranging from 10 to 120 days are studied. Spectra reveal that kinetic energy is peaked at 30 day periods with a weaker peak at 12 days. The most energetic empirical mode accounts for about 50% of the measured energy although somewhat less than this at higher subinertial frequencies. Consistent with the theoretical calculations of Gill, Green and Simmons it is found that the zonal phase propagation is nearly independent of frequency and averages about 12 cm s -1 toward the west. The 30 and 12 day energy peaks correspond to wavenumbers (wavelengths) of -0.18 km -1 (350 km) and -.033 km -1 (190 km) respectively. These are almost identical to the predicted scales for secondary and primary growth rate maxima for baroclinically unstable disturbances to a zonal current which is horizontally uniform but whose strength decreases exponentially with depth. Energy in these motions increases toward the west at a rate which is statistically indistinguishable from zero but also from the predicted rate. The vertical structure of these motions is also qualitatively similar to the theoretical modes. Phase for velocity decreases with depth, whereas temperature phase increases leading to energy release concentrated in the thermocline near the steering level which is projected to be somewhere above the shallowest observational level (600 m). The 30 day wave is much less depth dependent in amplitude than the 12 day wave and is responsible for the intense deep eddy field observed in this area by SCHMITZ (1977, 1978, 1980). At this point in the recirculation the instability process is still active and the resulting motions have not yet reached a finite amplitude state.
Scale and geometry effects on heat-recirculating combustors Chien-Hua Chen*
Scale and geometry effects on heat-recirculating combustors Chien-Hua Chen* and Paul D. Ronney**, *** * Advanced Cooling Technologies, Inc. 1046 New Holland Avenue Lancaster, PA 17601-5688 Chien-Hua.Chen@1-act
Soil nitrifying enrichments as biofilter starters in intensive recirculating saline water aquaculture
Gross, Amit
aquaculture Abstract Intensive recirculating aquaculture relies on biofilters to sustain satisfactory water quality in the ponds. Establishment of new biofilters in aquaculture ponds without a start-up culture
Fish Health Management Considerations in Recirculating Aquaculture systems -Part 3: General
Watson, Craig A.
Cir 122 Fish Health Management Considerations in Recirculating Aquaculture systems -Part 3: General Professor, Tropical Aquaculture Laboratory, Ruskin FL 33570, Department of Fisheries and Aquatic Sciences commonly used in aquaculture facilities, wholesale and retail tropical fish facilities, and public aquaria
The evaluation of oxygen and carbon dioxide transfer associated with airlifts in recirculating aquaculture systems
Technology Transfer Automated Retrieval System (TEKTRAN)
Airlifts in recirculating aquaculture systems (RAS) provide aeration, degasification, and water circulation. They allow the simplification of systems, and if designed properly, can reduce the capital costs and minimize operation and maintenance associated with alternative pumping systems. In order t...
Frankel, Arthur D.; Petersen, Mark D.
The geometry and recurrence times of large earthquakes associated with the Cascadia Subduction Zone (CSZ) were discussed and debated at a March 28-29, 2006 Pacific Northwest workshop for the USGS National Seismic Hazard Maps. The CSZ is modeled from Cape Mendocino in California to Vancouver Island in British Columbia. We include the same geometry and weighting scheme as was used in the 2002 model (Frankel and others, 2002) based on thermal constraints (Fig. 1; Fluck and others, 1997 and a reexamination by Wang et al., 2003, Fig. 11, eastern edge of intermediate shading). This scheme includes four possibilities for the lower (eastern) limit of seismic rupture: the base of elastic zone (weight 0.1), the base of transition zone (weight 0.2), the midpoint of the transition zone (weight 0.2), and a model with a long north-south segment at 123.8? W in the southern and central portions of the CSZ, with a dogleg to the northwest in the northern portion of the zone (weight 0.5). The latter model was derived from the approximate average longitude of the contour of the 30 km depth of the CSZ as modeled by Fluck et al. (1997). A global study of the maximum depth of thrust earthquakes on subduction zones by Tichelaar and Ruff (1993) indicated maximum depths of about 40 km for most of the subduction zones studied, although the Mexican subduction zone had a maximum depth of about 25 km (R. LaForge, pers. comm., 2006). The recent inversion of GPS data by McCaffrey et al. (2007) shows a significant amount of coupling (a coupling factor of 0.2-0.3) as far east as 123.8? West in some portions of the CSZ. Both of these lines of evidence lend support to the model with a north-south segment at 123.8? W.
Modeling gas transfer and biological respiration in a recirculating aquaculture system
Luther G. Wood; Barnaby J. Watten; C. Gene Haugh; George S. Libey; Theo A. Dillaha
Recirculating aquaculture system applications of oxygen absorption equipment require consideration of the combined effects of the system's physical, chemical and biological components. Interactions of this type were modeled within a recirculating system incorporating a mixed-flow type rearing vessel, a multi-tube clarifier, a rotating biological contactor (RBC) and a U-tube oxygenator. Finite difference mass transfer calculations, based on reactor theory, were
Ventilating characteristics of a recirculating air-curtain laboratory exhaust hood
Janes, Dale Floyd
VENTILATING CHARACTERISTICS OF A RECIRCULATING AIR-CURTAIN LABORATORY EXHAUST HOOD A Thesis by DALE FLOYD JANES Submitted to the Graduate College of Texas A8M University in partial fulfillment of the requirement for the degree of MASTER... OF SCIENCE August, 1978 Major Subject: Industrial Hygiene Copyright by Dale Floyd Janes 1978 443229 VENTILATING CHARACTERISTICS OF A RECIRCULATING AIR-CURTAIN LABORATORY EXHAUST HOOD A Thesis by DALE FLOYD JANES Approved as to style and content by...
Biologically Plausible Error-Driven Learning Using Local Activation Differences: The Generalized Recirculation Algorithm
Randall C. O'Reilly
The error backpropagation learning algorithm (BP) is generally considered biologically implausible because it does not use locally available, activation-based variables. A version of BP that can be computed locally using bidirectional activation recirculation (Hinton and McClelland 1988) instead of backpropagated error derivatives is more biologically plausible. This paper presents a generalized version of the recirculation algorithm (GeneRec), which overcomes several
Electrochemical hydrogen pump for recirculation of hydrogen in a fuel cell stack
Frano Barbir; Haluk G—rg■n
The objective of this work is to evaluate the use of an electrochemical hydrogen pump for recirculation of hydrogen in a fuel\\u000a cell stack. The hydrogen pump needed about 130 mV at 0.5 A cm?2, primarily because of the cell resistance (0.18 ? cm2). This voltage loss was higher than a fuel cell voltage gain resulting from hydrogen recirculation. However, if one pumping\\u000a cell is
Does the stationary viscous flow around a circular cylinder exist for large Reynolds numbers? A numerical solution via variational imbedding
NASA Astrophysics Data System (ADS)
Christov, Christo I.; Marinova, Rossitza S.; Marinov, Tchavdar T.
We propose an approach to identifying the solutions of the steady incompressible Navier-Stokes equations for large Reynolds numbers. These cannot be obtained as initial-value problems for the unsteady system because of the instability of the latter. Our approach consists of replacing the original steady-state problem for the Navier-Stokes equations by a boundary-value problem for the Euler-Lagrange equations for minimization of the quadratic functional of the original equations. This technique is called Method of Variational Imbedding (MVI) and in this case it leads to a system of higher-order partial differential equations, which is solved by means of an operator-splitting method. As a featuring example we consider the classical flow around a circular cylinder which is known to lose stability as early as for . We find a stationary solution with recirculation zone for Reynolds numbers as large as . Thus, new information about the possible hybrid flow regimes is obtained.
Anolyte recirculation effects in buffered and unbuffered single-chamber air-cathode microbial fuel cells.
Zhang, Liang; Zhu, Xun; Kashima, Hiroyuki; Li, Jun; Ye, Ding-ding; Liao, Qiang; Regan, John M
Two identical microbial fuel cells (MFCs) with a floating air-cathode were operated under either buffered (MFC-B) or bufferless (MFC-BL) conditions to investigate anolyte recirculation effects on enhancing proton transfer. With an external resistance of 50 ? and recirculation rate of 1.0 ml/min, MFC-BL had a 27% lower voltage (9.7% lower maximal power density) but a 64% higher Coulombic efficiency (CE) than MFC-B. MFC-B had a decreased voltage output, batch time, and CE with increasing recirculation rate resulting from more oxygen transfer into the anode. However, increasing the recirculation rate within a low range significantly enhanced proton transfer in MFC-BL, resulting in a higher voltage output, a longer batch time, and a higher CE. A further increase in recirculation rate decreased the batch time and CE of MFC-BL due to excess oxygen transfer into anode outweighing the proton-transfer benefits. The unbuffered MFC had an optimal recirculation rate of 0.35 ml/min. PMID:25514399
Atmospheric stagnation, recirculation and ventilation potential of several sites in Argentina
NASA Astrophysics Data System (ADS)
Venegas, L. E.; Mazzeo, N. A.
Conditions for stagnation, recirculation and ventilation potential of the atmosphere were studied in five argentine cities: Resistencia, Cµrdoba, Buenos Aires, Mar del Plata and Comodoro Rivadavia, located in different regions of the country. Wind run and recirculation factors were calculated for a 24-h transport time using 2 years of hourly surface measurements of wind speed and direction. The largest stagnation frequency (45% of the time) was observed in Resistencia, located in the northeastern part of the country, in an area where winds are weak. The least frequency of stagnations (2%) was observed in Comodoro Rivadavia, in the southern region of the country, a region dominated by strong westerly winds. Comodoro Rivadavia and Cµrdoba registered the largest frequency of recirculations. Comodoro Rivadavia exposed to sea-land breezes and Cµrdoba, located on a complex terrain area and exposed to local circulations, experienced recirculation events during 10% of the time. Good atmospheric ventilation occurs when a high value of wind run and a low value of the recirculation factor are observed and it can be associated with the atmosphere's capacity to replace polluted air with clean air. Ventilation events occurred 58% of the time at Comodoro Rivadavia, 52% at Mar del Plata, 40% at Buenos Aires, 35% at Cµrdoba and 18% at Resistencia. In general, stagnation was more frequently observed during autumn and winter, recirculation during spring and summer and good ventilation conditions occurred during spring.
Enhanced leachate recirculation and stabilization in a pilot landfill bioreactor in Taiwan.
Huang, Fu-Shih; Hung, Jui-Min; Lu, Chih-Jen
This study focused on the treatment of municipal solid waste (MSW) by modification and recirculation of leachate from a simulated landfill bioreactor. Hydrogen peroxide was added to recirculated leachate to maintain a constant oxygen concentration as the leachate passed again through the simulated landfill bioreactor. The results showed that leachate recirculation increased the dissolved oxygen concentration in the test landfill bioreactor. Over a period of 405 days, the biochemical oxygen demand (BOD(5)) in the collected leachate reduced by 99.7%, whereas the chemical oxygen demand (COD) reduced by 96%. The BOD(5)/COD ratio at the initial stage of 0.9 improved to 0.09 under aerobic conditions (leachate recirculation with added hydrogen peroxide) compared with the anaerobic test cell 0.11 (leachate recirculation alone without hydrogen peroxide). The pH increased from 5.5 to 7.6, and the degradation rate of organic carbon was 93%. Leachate recirculation brings about the biodegradation of MSW comparatively faster than the conventional landfill operation. The addition of a constant concentration of hydrogen peroxide was found to further increase the biodegradation. This increased biodegradation rate ultimately enables an MSW landfill to reach a stable state sooner and free up the land for further reuse. PMID:22767874
AMTEC recirculating test cell component testing and operation
NASA Astrophysics Data System (ADS)
Underwood, M. L.; Sievers, R. K.; O'Connor, D.; Williams, R. M.; Jeffries-Nakamura, B.; Bankston, C. P.
Alkali metal thermoelectric converter operation in a recirculating test cell (RTC), which requires a small electromagnetic pump (EM) and a high-temperature beta-double-prime alumina-solid-electrolyte (BASE)-to-metal seal, is discussed. The design of a pump and an active metal braze seal and the initial operation of a cell using these components are described. The pump delivered 0.25 cu cm/min against a 28-psia head. A braze seal system was selected after shear strength tests of Ta or Nb brazed to BASE by a variety of fillers including TiCuNi, TiNi, and TiNiCr. The TiCuNi filler was chosen for environment cell testing and showed no failure or observable degradation after short-term tests up to 1055 K. The pump and the Nb/TiCuNi/BASE seal were used in a test that demonstrated all the operational functions of the RTC for the first time. An increase in the radiation reduction factor at constant input power was observed, indicating that the condenser was being wet by sodium resulting in an increased reflectivity.
Aircraft Recirculation Filter for Air-Quality and Incident Assessment
Eckels, Steven J.; Jones, Byron; Mann, Garrett; Mohan, Krishnan R.; Weisel, Clifford P.
The current research examines the possibility of using recirculation filters from aircraft to document the nature of air-quality incidents on aircraft. These filters are highly effective at collecting solid and liquid particulates. Identification of engine oil contaminants arriving through the bleed air system on the filter was chosen as the initial focus. A two-step study was undertaken. First, a compressor/bleed air simulator was developed to simulate an engine oil leak, and samples were analyzed with gas chromatograph-mass spectrometry. These samples provided a concrete link between tricresyl phosphates and a homologous series of synthetic pentaerythritol esters from oil and contaminants found on the sample paper. The second step was to test 184 used aircraft filters with the same gas chromatograph-mass spectrometry system; of that total, 107 were standard filters, and 77 were nonstandard. Four of the standard filters had both markers for oil, with the homologous series synthetic pentaerythritol esters being the less common marker. It was also found that 90% of the filters had some detectable level of tricresyl phosphates. Of the 77 nonstandard filters, 30 had both markers for oil, a significantly higher percent than the standard filters. PMID:25641977
In situ treatment of VOCs by recirculation technologies
Siegrist, R.L.; Webb, O.F.; Ally, M.R.; Sanford, W.E. [Oak Ridge National Lab., TN (US); Kearl, P.M.; Zutman, J.L. [Oak Ridge National Lab., Grand Junction, CO (US)
The project described herein was conducted by Oak Ridge National Laboratory (ORNL) to identify processes and technologies developed in Germany that appeared to have near-term potential for enhancing the cleanup of volatile organic compound (VOC) contaminated soil and groundwater at DOE sites. Members of the ORNL research team identified and evaluated selected German technologies developed at or in association with the University of Karlsruhe (UoK) for in situ treatment of VOC contaminated soils and groundwater. Project activities included contacts with researchers within three departments of the UoK (i.e., Applied Geology, Hydromechanics, and Soil and Foundation Engineering) during fall 1991 and subsequent visits to UoK and private industry collaborators during February 1992. Subsequent analyses consisted of engineering computations, groundwater flow modeling, and treatment process modeling. As a result of these project efforts, two processes were identified as having near-term potential for DOE: (1) the vacuum vaporizer well/groundwater recirculation well and (2) the porous pipe/horizontal well. This document was prepared to summarize the methods and results of the assessment activities completed during the initial year of the project. The project is still ongoing, so not all facets of the effort are completely described in this document. Recommendations for laboratory and field experiments are provided.
Recent advances in AMTEC recirculating test cell performance
NASA Astrophysics Data System (ADS)
Underwood, Mark L.; Williams, Roger M.; Ryan, Margaret A.; Jeffries-Nakamura, Barbara; O'Connor, Dennis
The alkali metal thermal to electric converter (AMTEC) is an electrochemical device for the direct conversion of thermal energy to electrical energy with efficiencies potentially near Carnot. The future usefulness of AMTEC for space power conversion depends on the efficiency of the devices. Systems studies have projected from 15% to 35% thermal to electric conversion efficiencies, and one experiment has demonstrated 19% efficiency for a short period of time. A recent experiment in a recirculating test cell (RCT) has demonstrated sustained conversion efficiencies as high as 13.2%. The cell was operated at lower current and 12% efficiency for over 1700 hours at the time of this writing. The cell required a maturation period of 355 hours at high temperature. During this period, the cell was operated once at 12% efficiency but was generally operated at lower powers. The maturation period ended with the formation of a reflective sodium film on the condenser surface which reduced the parasitic thermal losses in the cell. After maturation, the cell demonstrated the first experimental demonstration of the maximum efficiency occuring at a lower current than the maximum power. The cell also demonstrated an unexpected decrease in parasitic loss with increasing cell current. The decrease in parasitic loss resulted from the development of a more reflective sodium film at higher sodium fluxes.
Efficiency of an AMTEC recirculating test cell, experiments and projections
NASA Astrophysics Data System (ADS)
Underwood, M. L.; O'Connor, D.; Williams, R. M.; Jeffries-Nakamura, B.; Ryan, M. A.
The alkali metal thermal to electric converter (AMTEC) is an electrochemical device for the direct conversion of heat to electrical energy with efficiencies potentially near Carnot. The future usefulness of AMTEC for space power conversion depends on the efficiency of the devices. Systems studies have projected from 15 to 35 percent thermal to electric conversion efficiencies, and one experiment has demonstrated 19 percent efficiency for a short period of time. Recent experiments in a recirculating test cell (RTC) have demonstrated sustained conversion efficiencies as high as 10.2 percent early in cell life and 9.7 percent after maturity. Extensive thermal and electrochemical analysis of the cell during several experiments demonstrated that the efficiency could be improved in two ways. First, the electrode performance could be improved. The electrode for these tests operated at about one third the power density of state of the art electrodes. The low power density was caused by a combination of high series resistance and high mass flow resistance. Reducing these resistances could improve the efficiency to greater than 10 percent. Second, the cell thermal performance could be improved. Efficiencies greater than 14 percent could be realized through reducing the radiative thermal loss. Further improvements to the efficiency range predicted by systems studies can be accomplished through the development and use of an advanced condenser with improved reflectivity, close to that of a smooth sodium film, and the series connecting of individual cells to further reduce thermal losses.
Efficiency of an AMTEC recirculating test cell, experiments, and projections
NASA Astrophysics Data System (ADS)
Underwood, M. L.; Oconnor, D.; Williams, R. M.; Jeffries-Nakamura, B.; Ryan, M. A.
The alkali metal thermal to electric converter (AMTEC) is an electrochemical device for the direct conversion of heat to electrical energy with efficiencies potentially near Carnot. The future usefulness of AMTEC for space power conversion depends on the efficiency of the devices. Systems studies have projected from 15 to 35 percent thermal to electric conversion efficiencies, and one experiment has demonstrated 19 percent efficiency for a short period of time. Recent experiments in a recirculating test cell (RTC) have demonstrated sustained conversion efficiencies as high as 10.2 percent early in cell life and 9.7 percent after maturity. Extensive thermal and electrochemical analysis of the cell during several experiments demonstrated that the efficiency could be improved in two ways. First, the electrode performance could be improved. The electrode for these tests operated at about one third the power density of state of the art electrodes. The low power density was caused by a combination of high series resistance and high mass flow resistance. Reducing these resistances could improve the efficiency to greater than 10 percent. Second, the cell thermal perform ance could be improved. Efficiencies greater than 14 percent could be realized through reducing the radiative thermal loss. Further improvements to the efficiency range predicted by systems studies can be accomplished through the development and use of an advanced condenser with improved reflectivity, close to that of a smooth sodium film, and the series connecting of individual cells to further reduce thermal losses.
Efficiency of an AMTEC recirculating test cell, experiments and projections
Underwood, M.L.; O`Connor, D.; Williams, R.M.; Jeffries-Nakamura, B.; Ryan, M.A.
The alkali metal thermal to electric converter (AMTEC) is an electrochemical device for the direct conversion of heat to electrical energy with efficiencies potentially near Carnot. The future usefulness of AMTEC for space power conversion depends on the efficiency of the devices. Systems studies have projected from 15% to 35% thermal to electric conversion efficiencies, and one experiment has demonstrated 19% efficiency for a short period of time. Recent experiments in a recirculating test cell (RTC) have demonstrated sustained conversion efficiencies as high as 10.2% early in cell life and 9.7% after maturity. Extensive thermal and electrochemical analysis of the cell during several experiments demonstrated that the efficiency could be improved in two ways. First, the electrode performance could be improved. The electrode for these tests operated at about one third the power density of state of the art electrodes. The low power density was caused by a combination of high series resistance and high mass flow resistance. Reducing these resistances could improve the efficiency to greater than 10%. Second, the cell thermal performance could be improved. Efficiencies greater than 14% could be realized through reducing the radiative thermal loss. Further improvements to the efficiency range predicted by systems studies can be accomplished through the development and use of an advanced condenser with improved reflectivity, close to that of a smooth sodium film, and the series connecting of individual cells to further reduce thermal losses.
AMTEC recirculating test cell component testing and operation
NASA Technical Reports Server (NTRS)
Underwood, M. L.; Sievers, R. K.; O'Connor, D.; Williams, R. M.; Jeffries-Nakamura, B.; Bankston, C. P.
Alkali metal thermoelectric converter operation in a recirculating test cell (RTC), which requires a small electromagnetic pump (EM) and a high-temperature beta-double-prime alumina-solid-electrolyte (BASE)-to-metal seal, is discussed. The design of a pump and an active metal braze seal and the initial operation of a cell using these components are described. The pump delivered 0.25 cu cm/min against a 28-psia head. A braze seal system was selected after shear strength tests of Ta or Nb brazed to BASE by a variety of fillers including TiCuNi, TiNi, and TiNiCr. The TiCuNi filler was chosen for environment cell testing and showed no failure or observable degradation after short-term tests up to 1055 K. The pump and the Nb/TiCuNi/BASE seal were used in a test that demonstrated all the operational functions of the RTC for the first time. An increase in the radiation reduction factor at constant input power was observed, indicating that the condenser was being wet by sodium resulting in an increased reflectivity.
Recent advances in AMTEC recirculating test cell performance
Underwood, M.L.; Williams, R.M.; Ryan, M.A.; Jeffries-Nakamura, B.; O'Connor, D. (Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109 (United States))
The alkali metal thermal to electric converter (AMTEC) is an electrochemical device for the direct conversion of thermal energy to electrical energy with efficiencies potentially near Carnot. The future usefulness of AMTEC for space power conversion depends on the efficiency of the devices. Systems studies have projected from 15% to 35% thermal to electric conversion efficiencies, and one experiment has demonstrated 19% efficiency for a short period of time. A recent experiment in a recirculating test cell (RCT) has demonstrated sustained conversion efficiencies as high as 13.2%. The cell was operated at lower current and 12% efficiency for over 1700 hours at the time of this writing. The cell required a maturation period of 355 hours at high temperature. During this period, the cell was operated once at 12% efficiency but was generally operated at lower powers. The maturation period ended with the formation of a reflective sodium film on the condenser surface which reduced the parasitic thermal losses in the cell. After maturation, the cell demonstrated the first experimental demonstration of the maximum efficiency occuring at a lower current than the maximum power. The cell also demonstrated an unexpected decrease in parasitic loss with increasing cell current. The decrease in parasitic loss resulted from the development of a more reflective sodium film at higher sodium fluxes.
A recirculating coronal discharge system for air cleaning
Vogtlin, G.E.; Hofer, W.W.; Penetrante, B.M. [Lawrence Livermore National Lab., CA (United States)] [and others
A recirculating gas cleaning system has been constructed incorporating a pulsed plasma reactor in coaxial cylinder geometry, with a wire of diameter 1.59mm inside a stainless steel cylinder of inner radius 10.6mm. Positive corona are formed by the application of pulses of up to 45 kV with rise times of 10-20 ns, pulse lengths of 50-200 ns and peak currents up to 500 A. Higher voltages lead to premature arc formation. Flow rates of up to 2 liters per second can be achieved in the 4.6 liter gas system, and filters are included to remove the acids formed from the pollutant molecules. First tests of the system using NO at initial levels around 100 ppm show that 99% destruction can be achieved with approximately 250 pulses. No NO removal is seen if the air is replaced by dry nitrogen, showing the crucial role of radicals produced from O{sub 2} and/or H{sub 2}O. Further experiments are underway to determine the dependence of the process efficiency on the electrical characteristics, and on the humidity level of the air, and to check the predictions of discharge simulations described elsewhere at this meeting.
Intraplate tectonics in Asia: A precise age for large-scale Miocene movement along the Ailao Shan-Red River shear zone, China
NASA Astrophysics Data System (ADS)
Schðrer, Urs; Tapponnier, Paul; Lacassin, Robin; Leloup, Philippe H.; Zhong, Dalai; Ji, Shaocheng
Tertiary left-lateral movement along the 1000 km long Ailao Shan-Red River shear zone appears to have played an important role in absorbing post-collisional northward penetration of India into Asia. Crustal strike-slip shear along this zone caused the formation of a gneiss belt, metamorphosed to amphibolite grade, including anatectic melting. Both metamorphism and melting were induced by ductile deformation yielding the possibility to date the major tectonometamorphic event that shaped the Ailao Shan-Red River belt. 17 U-Pb isotope analyses were performed on small size-fractions of zircon, monazite and xenotime, extracted from two different leucogranitic layers. The two samples are located about 50 km apart in the central segment of Ailao Shan, in structurally well controlled settings where the melts crystallized within the strongly foliated gneisses during late stages of deformation. All mineral U-Pb analyses had to be corrected for excess or deficit amounts of radiogenic 206Pb, originating from initial 230Th disequilibrium in the 238U decay series. In monazite, such disequilibrium 206Pb reaches 20% of total radiogenic 206Pb. The corrected U-Pb ages of monazite and xenotime lie between 22.1 and 23.9 Ma, whereas zircon yields significantly discordant U-Pb ages between 30.5 and 33.9 Ma pointing to Precambrian material in the magma source region. Inherited components could also be detected in monazite. The set of U-Pb data shows that monazite and xenotime formed simultaneously in both localities substantiating an early Miocene age of 23.0 Ý 0.2Ma for late kinematic crystallization of anatectic melts in the metamorphic belt of the Ailao Shan-Red River shear zone.
Temporal and Spatial Pore Water Pressure Distribution Surrounding a Vertical Landfill Leachate Recirculation Well
Kadambala, Ravi; Townsend, Timothy G.; Jain, Pradeep; Singh, Karamjit
Addition of liquids into landfilled waste can result in an increase in pore water pressure, and this in turn may increase concerns with respect to geotechnical stability of the landfilled waste mass. While the impact of vertical well leachate recirculation on landfill pore water pressures has been mathematically modeled, measurements of these systems in operating landfills have not been reported. Pressure readings from vibrating wire piezometers placed in the waste surrounding a liquids addition well at a full-scale operating landfill in Florida were recorded over a 2-year period. Prior to the addition of liquids, measured pore pressures were found to increase with landfill depth, an indication of gas pressure increase and decreasing waste permeability with depth. When liquid addition commenced, piezometers located closer to either the leachate injection well or the landfill surface responded more rapidly to leachate addition relative to those far from the well and those at deeper locations. After liquid addition stopped, measured pore pressures did not immediately drop, but slowly decreased with time. Despite the large pressures present at the bottom of the liquid addition well, much smaller pressures were measured in the surrounding waste. The spatial variation of the pressures recorded in this study suggests that waste permeability is anisotropic and decreases with depth. PMID:21655145
Advanced Horizontal Well Recirculation Systems for Geothermal Energy Recovery in Sedimentary Formations
Mike Bruno; Russell L. Detwiler; Kang Lao; Vahid Serajian; Jean Elkhoury; Julia Diessl; Nicky White
There is increased recognition that geothermal energy resources are more widespread than previously thought, with potential for providing a significant amount of sustainable clean energy worldwide. Recent advances in drilling, completion, and production technology from the oil and gas industry can now be applied to unlock vast new geothermal resources, with some estimates for potential electricity generation from geothermal energy now on the order of 2 million megawatts. Terralog USA, in collaboration with the University of California, Irvine (UCI), are currently investigating advanced design concepts for paired horizontal well recirculation systems, optimally configured for geothermal energy recovery in permeable sedimentary and crystalline formations of varying structure and material properties. This two-year research project, funded by the US Department of Energy, includes combined efforts for: 1) Resource characterization; 2) Small and large scale laboratory investigations; 3) Numerical simulation at both the laboratory and field scale; and 4) Engineering feasibility studies and economic evaluations. The research project is currently in its early stages. This paper summarizes our technical approach and preliminary findings related to potential resources, small-scale laboratory simulation, and supporting numerical simulation efforts.
Mineral and organic compounds in leachate from landfill with concentrate recirculation.
Talalaj, Izabela Anna
The effect of a reverse osmosis concentrate recirculation on the mineral and organic compounds in a landfill leachate was investigated. Investigated was the quality of a leachate from two landfills operated for different periods (a 20-year-old Cell A and a 1-year-old Cell B), where the concentrate was recirculated. Examined were general parameters (conductivity, pH), organic compounds (biochemical oxygen demand (BOD), chemical oxygen demand (COD), total organic nitrogen, BOD/COD), and inorganic compounds (nitrogen ammonia, sulfite, sulfate, cyanide, boron, chloride, ferrous, zinc, chrome, copper). The findings from the first year of investigation showed that over the initial period of recirculation, the concentration of organic compounds (BOD, COD) increased, but after 6 months their values stabilized. It indicates that the concentrate recirculation accelerated organic decomposition, especially in the new landfill Cell. The analysis of inorganic parameters showed that recirculation landfills produce a leachate with a higher concentration of N-NH4, and Cl(-). In case of the old landfill Cell, an increase in B and Fe was also noticeable. These compounds are cyclically washed out from a waste dump and require an additional pretreatment in order to exclude them from recirculation cycle. The increased concentration of Cu, Zn, and Fe was noticed during the initial months of recirculation and in the season of intense atmospheric precipitation in the leachate from both Cells. Higher values of electro conductivity, Cl(-), N-NH4 (+), B, and Fe in the leachate from the old field indicate that the attenuation capacity of this landfill is close to exhaustion. PMID:25194843
Effect of heat recirculation on the self-sustained catalytic combustion of propane\\/air mixtures in a quartz reactor
A. Scarpa; R. Pirone; G. Russo; D. G. Vlachos
The self-sustained catalytic combustion of propane is experimentally studied in a two-pass, quartz heat-recirculation reactor (HRR) and compared to that in a no (heat) recirculation reactor (NRR). Structured monolithic reactors with Pt\\/?-Al2O3, LaMnO3\\/?-Al2O3, and Pt doped perovskite catalysts have been compared in the HRR and NRR configurations. Heat recirculation enhances combustion stability, by widening the operating window of self-sustained operation,
Electron recirculation in electrostatic multicusp systems: II. System performance scaling of one-dimensional rollover wells
Bussard, R.W.; King, K.E.
In an earlier paper a comprehensive study was made of the recirculation and losses of electrons in their flow through simple inverse power-law potential wells bounded by similarly inverse power-law dependent magnetic fields. This study examined electron flow and loss behavior in the simplest approximation invoked to describe Polywell confinement systems. The importance of this study, and of the present paper, is that the power balance in Polywell systems is determined entirely by the rate of electron losses; if these are large, then the system can not yield net power. Thus it is of interest to determine those conditions that results in small losses, and to design experiments and systems to attempt to achieve and operate at these most favorable conditions, in order to test and prove the efficacy of the system for the generation of net power from fusion reactions. The outline and summary of this problem presented is generally repeated here, with some modifications to clarify particular physics issues of most concern, in order to avoid having to refer to the earlier document for this general description. As noted, a large body of work has been undertaken over the past 35 or so years in the study of general cusp confinement of plasmas. Nearly all of this has examined single particle electron (or ion) motion or the motion of particles in neutral plasmas within cusped magnetic systems, generally without internal electric potential fields.**INVALID KEYWORDS: controlled nuclear fusion, electron flux, plasma devices, confinement, performance, engineering, scaling factor, multicusp systems, polywell systems
[Research on the variation regularity of effluent from the leachate reverse osmosis concentrate recirculation].
Wang, Dong-Mei; Liu, Dan; Liu, Qing-Mei; Tao, Li-Xia; Liu, Ying
To provide certain theoretical basis for selecting recirculation landfill scientifically and reasonably, the variation regularity of recirculation effluent from the landfill columns in three different years was studied. By using leachate reverse osmosis concentrate from a refuse landfill in Chengdu, the recirculation experiments were carried out in three landfill columns filled with garbage in 1, 5 and 15 landfill ages respectively. The variation regularity of pH, total organic carbon, ammonia nitrogen, nitrate nitrogen and heavy metals of recirculation effluent was researched. It showed that the one-year landfill column with a favorable ability of removing nitrate nitrogen and degradation rate of nitrate nitrogen reaching above 88% was in the stage of producing methanation, but the concentration of organic matter and ammonia nitrogen of the effluent is higher and changes in the parameters mainly depend on the biological function. The five-year landfill column without typical features of mineralized refuse and with relatively poor adsorption capacity and biological effects, as well as removal capacity of organic matter, salinity, Cr and Ni approaches stabilization. The fifteen-year landfill column has high capability of adsorption, complexing, as well as organic matter, salinity, Cr and Ni removal, and the removal rate at the initial stage reaches 90%, 78%, 93% and 78%, respectively, but the recirculation process and progress need to be controlled when the rate approaches or reaches the adsorption capacity. PMID:25244874
Performance of Water Recirculation Loop Maintenance Components for the Advanced Spacesuit Water Membrane Evaporator
NASA Technical Reports Server (NTRS)
Rector, Tony; Peyton, Barbara M.; Steele, John W.; Makinen, Janice; Bue, Grant C.; Campbell, Colin
Water loop maintenance components to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop have undergone a comparative performance evaluation with a recirculating control loop which had no water quality maintenance. Results show that periodic water maintenance can improve performance of the SWME. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage of this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing sublimator technology. The driver for the evaluation of water recirculation maintenance components was to enhance the robustness of the SWME through the leveraging of fluid loop management lessons learned from the International Space Station (ISS). A patented bed design that was developed for a United Technologies Aerospace System military application provided a low pressure drop means for water maintenance in the SWME recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The maintenance cycle included the use of a biocide delivery component developed for the ISS to introduce a biocide in a microgravity compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware.
Enhancement of denitrification in a down-flow hanging sponge reactor by effluent recirculation.
Ikeda, N; Natori, T; Okubo, T; Sugo, A; Aoki, M; Kimura, M; Yamaguchi, T; Harada, H; Ohashi, A; Uemura, S
A down-flow hanging sponge reactor, constructed by connecting three identical units in series, was applied to the treatment of artificial wastewater containing phenol and ammonia under high salinity conditions (10.9 g-Cl(-)/L). The theoretical hydraulic retention time (HRT) of each unit was 4 h (total HRT = 12 h). To enhance denitrification by effluent recirculation, the effluent recirculation ratio was increased in increments ranging from 0.0 to 2.0. The concentration of total ammonia nitrogen (TAN), NO2-N, and NO3-N in the final effluent as a proportion of the TAN in the influent was determined to calculate the unrecovered, or denitrification, proportion. The denitrification proportion of the reactor was equivalent to 19.1 Ý 14.1% with no effluent recirculation; however, this was increased to 58.6 Ý 6.2% when the effluent recirculation ratio was increased to 1.5. Further increasing the effluent recirculation ratio to 2.0 resulted in a decrease in the denitrification proportion to 50.9 Ý 9.3%. Activity assays of nitrification and denitrification, as well as 16S rRNA gene sequence analysis, revealed that denitrification occurred primarily in the upper sections of the reactor, while nitrification increased in the lower sections of the reactor. Gene sequence analysis revealed that denitrification by Azoarcus-like species using phenol as an electron donor was dominant. PMID:23925187
Exhaust gas recirculation control method and apparatus for internal combustion engine
Tsutsumi, K.
An exhaust gas recirculation control method is described for operating an exhaust gas recirculation control device including a needle valve provided in an exhaust gas recirculation passage for setting an effective diameter of the passage, a position sensor for providing a signal representing a position of the needle valve, and a negative pressure motor for positioning the needle valve. The method comprises: setting a target value for the needle valve according to predetermined operating conditions of the internal combustion engine; measuring a positional deviation between the target value and an actual position of the needle valve as represented by the signal provided by the position sensor; and driving the negative pressure motor with only a single drive pulse having a time width corresponding to the measured positional deviation. An exhaust gas recirculation control apparatus is described for operating an exhaust gas recirculation control device. The apparatus comprises: means for setting a target value for the needle valve according to predetermined operating conditions of the internal combustion engine; and means for measuring a positional deviation between the target value and an actual position of the needle valve as represented by the signal provided by the position sensor.
Radioactive particle tracking technique for investigation of phase recirculation and turbulence in multiphase systems
NASA Astrophysics Data System (ADS)
Moslemian, D.; Devanathan, N.; Dudukovic, M. P.
The development of a noninvasive PC-based computer automated radioactive particle tracking (CARPT) facility for investigation of phase recirculation and turbulence in multiphase systems such as fluidized beds and bubble columns is presented. In this facility, the motion of a single radioactive particle, which is dynamically similar to the recirculating phase, is monitored by an array of scintillation detectors which surround the test section. An on-line computer is used to map the flow field of the recirculating phase. The data acquisition is achieved by commercially available nuclear instrumentation via a modular, high-speed GPIB-CAMAC system through assembly language software. Using CARPT, solids' motion in gas-fluidized beds and liquid motion in bubble columns have been investigated. The capabilities and versatility of the CARPT facility is described by illustrating some typical results for mean recirculation in gas-fluidized beds with and without internals and in a gas-liquid bubble column. The results include the mean circulation profiles and turbulence parameters such as the Reynolds normal and shear stresses and the turbulent eddy dispersion coefficients. Potential applications of CARPT technique to other recirculating systems are also discussed.
Anaerobic degradation of dairy wastewater in intermittent UASB reactors: influence of effluent recirculation.
Couras, C S; Louros, V L; Gameiro, T; Alves, N; Silva, A; Capela, M I; Arroja, L M; Nadais, H
This work studied the influence of effluent recirculation upon the kinetics of anaerobic degradation of dairy wastewater in the feedless phase of intermittent upflow anaerobic sludge bed (UASB) reactors. Several laboratory-scale tests were performed with different organic loads in closed circuit UASB reactors inoculated with adapted flocculent sludge. The data obtained were used for determination of specific substrate removal rates and specific methane production rates, and adjusted to kinetic models. A high initial substrate removal was observed in all tests due to adsorption of organic matter onto the anaerobic biomass which was not accompanied by biological substrate degradation as measured by methane production. Initial methane production rate was about 45% of initial soluble and colloidal substrate removal rate. This discrepancy between methane production rate and substrate removal rate was observed mainly on the first day of all experiments and was attenuated on the second day, suggesting that the feedless period of intermittent UASB reactors treating dairy wastewater should be longer than one day. Effluent recirculation expressively raised the rate of removal of soluble and colloidal substrate and methane productivity, as compared with results for similar assays in batch reactors without recirculation. The observed bed expansion was due to the biogas production and the application of effluent recirculation led to a sludge bed contraction after all the substrates were degraded. The settleability of the anaerobic sludge improved by the introduction of effluent recirculation this effect being more pronounced for the higher loads. PMID:25803484
Field evaluation of a horizontal well recirculation system for groundwater treatment: Field demonstration at X-701B Portsmouth Gaseous Diffusion Plant, Piketon, Ohio
Korte, N.; Muck, M.; Kearl, P.; Siegrist, R.; Schlosser, R.; Zutman, J. [Oak Ridge National Lab., TN (United States)] [Oak Ridge National Lab., TN (United States); Houk, T. [Lockheed Martin Energy Systems, Piketon, OH (United States). Portsmouth Gaseous Diffusion Plant] [Lockheed Martin Energy Systems, Piketon, OH (United States). Portsmouth Gaseous Diffusion Plant
This report describes the field-scale demonstration performed as part of the project, In Situ Treatment of Mixed Contaminants in Groundwater. This project was a 3{1/2} year effort comprised of laboratory work performed at Oak Ridge National Laboratory and fieldwork performed at the US Department of Energy (DOE) Portsmouth Gaseous Diffusion Plant (PORTS). The overall goal of the project was to evaluate in situ treatment of groundwater using horizontal recirculation coupled with treatment modules. Specifically, horizontal recirculation was tested because of its application to thin, interbedded aquifer zones. Mixed contaminants were targeted because of their prominence at DOE sites and because they cannot be treated with conventional methods. The project involved several research elements, including treatment process evaluation, hydrodynamic flow and transport modeling, pilot testing at an uncontaminated site, and full-scale testing at a contaminated site. This report presents the results of the work at the contaminated site, X-701B at PORTS. Groundwater contamination at X-701B consists of trichloroethene (TCE) (concentrations up to 1800 mg/L) and technetium-998 (Tc{sup 99}) (activities up to 926 pCi/L).
Final cooling of coke oven gas using a closed-loop, recirculated wash-water system
Watkins, R.E.; Burcaw, K.R.
Bethlehem Steel Corporation has developed a closed-loop, recirculated wash-water system for the final cooling of coke oven gas streams. The system employs physical separation of suspended solids from the cooling water, indirect cooling of the recirculating water, and injection of a small amount of a water-immiscible solvent to minimise the deposition of naphthalenic solids in the indirect heat exchanger. A process patent (US Patent 4.234.389) has been awarded to Bethlehem for the solvent-injection portion of the process. Based on the results of plant trials, the system has been proven to require less capital investment and to be more economical and more reliable to operate than the standard recirculated wash-oil systems. When compared with existing wash-water systems, the system has the advantage of eliminating the atmospheric discharges associated with open cooling towers.
Effects of anti-recirculation ring on performance of an automotive cooling fan
NASA Astrophysics Data System (ADS)
Chen, Q. G.; Zhang, Y. C.; Li, F.; Kong, X. Z.; Luan, X. H.
An investigation has been conducted to evaluate the effects of anti-recirculation ring on performance of automotive axial flow cooling fan by CFD simulation. In order to reduce the element size and save computing time, periodic boundary condition and single flow channel has been applied to the simulation. The grid is composed of tetrahedral mesh and hexahedral mesh. The SST k - ? turbulence model and standard wall function method have been used. CFD results show that optimal design of pressure loss anti-recirculation ring can not only increase P-Q performance and aerodynamic efficiency, but also can improve the pressure distribution on fan tip which can reduce the axial deformation of cooling fan. So it can be proved that good design of anti-recirculation ring will not increase the total axial size of an axial cooling fan.
Two dimensional aspects of regenerative bbu in two-pass recirculating accelerators
Eduard Pozdeyev
In this paper, I present the formula, describing a threshold of the regenerative multi-pass Beam Breakup (BBU) for a single dipole higher order mode with arbitrary polarization in a two-pass accelerator with a general-form, 4 x 4 recirculation matrix. To illustrate specifics of the BBU in two dimensions, the formula is used to calculate the threshold for the reflecting and rotating optics of the recirculator that can lead to higher threshold currents. Then, I present a mathematical relation between transfer matrices between cavities of the accelerating structure and recirculation matrices for each cavity, which must be satisfied in order to successfully suppress the BBU by reflection or rotation in several cavities.
The impact of recirculation, ventilation and filters on secondary organic aerosols generated by indoor chemistry
NASA Astrophysics Data System (ADS)
Fadeyi, M. O.; Weschler, C. J.; Tham, K. W.
This study examined the impact of recirculation rates (7 and 14 h -1), ventilation rates (1 and 2 h -1), and filtration on secondary organic aerosols (SOAs) generated by ozone of outdoor origin reacting with limonene of indoor origin. Experiments were conducted within a recirculating air handling system that serviced an unoccupied, 236 m 3 environmental chamber configured to simulate an office; either no filter, a new filter or a used filter was located downstream of where outdoor air mixed with return air. For otherwise comparable conditions, the SOA number and mass concentrations at a recirculation rate of 14 h -1 were significantly smaller than at a recirculation rate of 7 h -1. This was due primarily to lower ozone concentrations, resulting from increased surface removal, at the higher recirculation rate. Increased ventilation increased outdoor-to-indoor transport of ozone, but this was more than offset by the increased dilution of SOA derived from ozone-initiated chemistry. The presence of a particle filter (new or used) strikingly lowered SOA number and mass concentrations compared with conditions when no filter was present. Even though the particle filter in this study had only 35% single-pass removal efficiency for 100 nm particles, filtration efficiency was greatly amplified by recirculation. SOA particle levels were reduced to an even greater extent when an activated carbon filter was in the system, due to ozone removal by the carbon filter. These findings improve our understanding of the influence of commonly employed energy saving procedures on occupant exposures to ozone and ozone-derived SOA.
Zone control of lean gas underfiring for coke ovens
Corbman, P.; Faber, P.V.
A coke oven battery is disclosed of the type that is underfired with coke oven gas. A system of horizontal bus flues and valve controls is provided for controlling the supply of lean gas fuel, such as blast furnace gas or any other lean gas, selectively to the gas flues in heating zones of the coke oven chamber walls and the recirculation of waste gas therefrom, so as to achieve the optimum fuel consumption under varying bulk density conditions of the coal mass in the coke oven chamber from the coke side to the pusher side.
Un formalisme de systemes a sauts pour la recirculation optimale des casses dans une machine a papier
NASA Astrophysics Data System (ADS)
Khanbaghi, Maryam
Increasing closure of white water circuits is making mill productivity and quality of paper produced increasingly affected by the occurrence of paper breaks. In this thesis the main objective is the development of white water and broke recirculation policies. The thesis consists of three main parts, respectively corresponding to the synthesis of a statistical model of paper breaks in a paper mill, the basic mathematical setup for the formulation of white water and broke recirculation policies in the mill as a jump linear quadratic regulation problem, and finally the tuning of the control law based on first passage-time theory, and its extension to the case of control sensitive paper break rates. More specifically, in the first part a statistical model of paper machine breaks is developed. We start from the hypothesis that the breaks process is a Markov chain with three states: the first state is the operational one, while the two others are associated with the general types of paper-breaks that can take place in the mill (wet breaks and dry breaks). The Markovian hypothesis is empirically validated. We also establish how paper-break rates are correlated with machine speed and broke recirculation ratio. Subsequently, we show how the obtained Markov chain model of paper-breaks can be used to formulate a machine operating speed parameter optimization problem. In the second part, upon recognizing that paper breaks can be modelled as a Markov chain type of process which, when interacting with the continuous mill dynamics, yields a jump Markov model, jump linear theory is proposed as a means of constructing white water and broke recirculation strategies which minimize process variability. Reduced process variability comes at the expense of relatively large swings in white water and broke tanks level. Since the linear design does not specifically account for constraints on the state-space, under the resulting law, damaging events of tank overflow or emptiness can occur. A heuristic simulation-based approach is proposed to choose the performance measure design parameters to keep the mean time between incidents of fluid in broke and white water tanks either overflowing, or reaching dangerously low levels, sufficiently long. In the third part, a methodology, mainly founded on the first passage-time theory of stochastic processes, is proposed to choose the performance measure design parameters to limit process variability while accounting for the possibility of undesirable tank overflows or tank emptiness. The heart of the approach is an approximation technique for evaluating mean first passage-times of the controlled tanks levels. This technique appears to have an applicability which largely exceeds the problem area it was designed for. Furthermore, the introduction of control sensitive break rates and the analysis of the ensuing control problem are presented. This is to account for the experimentally observed increase in breaks concomitant with flow rate variability.
Hybrid heat exchange for the compression capture of CO2 from recirculated flue gas
Oryshchyn, Danylo B.; Ochs, Thomas L.; Summers, Cathy A.
An approach proposed for removal of CO2 from flue gas cools and compresses a portion of a recirculated flue-gas stream, condensing its volatile materials for capture. Recirculating the flue gas concentrates SOx, H2O and CO2 while dramatically reducing N2 and NOx, enabling this approach, which uses readily available industrial components. A hybrid system of indirect and direct-contact heat exchange performs heat and mass transfer for pollutant removal and energy recovery. Computer modeling and experimentation combine to investigate the thermodynamics, heat and mass transfer, chemistry and engineering design of this integrated pollutant removal (IPR) system.
Performance of the prototype gas recirculation system with built-in RGA for INO RPC system
NASA Astrophysics Data System (ADS)
Bhuyan, M.; Datar, V. M.; Joshi, A.; Kalmani, S. D.; Mondal, N. K.; Rahman, M. A.; Satyanarayana, B.; Verma, P.
An open loop gas recovery and recirculation system has been developed for the INO RPC system. The gas mixture coming from RPC exhaust is first desiccated by passing through molecular sieve (3 é+4 é). Subsequent scrubbing over basic active alumina removes toxic and acidic contaminants. The Isobutane and Freon are then separated by diffusion and liquefied by fractional condensation by cooling up to -26C. A Residual Gas Analyser (RGA) is being used in the loop to study the performance of the recirculation system. The results of the RGA analysis will be discussed.
Comparison of hydroponic crop production techniques in a recirculating fish culture system
Wren, Steven Whitaker
and usefulness for water treatment in a recirculating fish culture system. Both hydroponic techniques were incorporated into one recirculating ~Tile ia auras culture system to insure uniformity of hydroponic influent water. The hydroponic strategies were... and phosphate. They grew tomatoes and channel catfish. Each system had an 870 L fish tank followed by rotating disc biofilters, a 200 L settling tank, and hydroponic tanks, A flow rate of 10 L/minute led to a turnover rate of 1. 45 hours in the fish tanks...
Large Pore Ion and Metabolite-Permeable Channel Regulation of Postnatal Ventricular Zone Neural Stem and Progenitor Cells: Interplay between Aquaporins, Connexins, and Pannexins?
Wicki-Stordeur, Leigh E.; Swayne, Leigh Anne
The birth of new neurons from unspecialized neural stem and progenitor cells surrounding the lateral ventricles occurs throughout postnatal life. This process, termed neurogenesis, is complex and multistepped, encompassing several types of cellular behaviours, such as proliferation, differentiation, and migration. These behaviours are influenced by numerous factors present in the unique, permissive microenvironment. A major cellular mechanism for sensing the plethora of environmental cues directing this process is the presence of different channel forming proteins spanning the plasma membrane. So-called large pore membrane channels, which are selective for the passage of specific types of small molecules and ions, are emerging as an important subgroup of channel proteins. Here, we focus on the roles of three such large pore channels, aquaporin 4, connexin 43, and pannexin 1. We highlight both their independent functions as well as the accumulating evidence for crosstalk between them. PMID:22754577
Exhaust Gas Recirculation in Gas Turbines for Reduction of CO2 Emissions; Combustion Testing with Focus on Stability and Emissions
Petter E. R½kke; Johan E. Hustad
Exhaust gas recirculation can be applied with the intention of reducing CO2 emissions. When a fraction of the exhaust gas is injected in the entry of a gas turbine, the amount of CO2 in the exhaust gas not being recirculated will be higher and less complicated to capture. However, with this change in combustion air composition, especially the reduced concentration
Numerical Modeling of Non-adiabatic Heat-Recirculating Combustors C. H. Kuo and P. D. Ronney
@usc.edu Colloquium topic area: 12. New Technology Concepts Keywords: Micro-combustion, Heat-recirculating combustors) for propane-air mixtures. These limits showed reasonable quantitative agreement with experiments. Comparison affect the performance of heat-recirculating combustors, but the relative importance of such effects
Use of a micro programmable logic controller for oxygen monitoring and control in multiple tanks of a recirculating aquaculture system
Technology Transfer Automated Retrieval System (TEKTRAN)
In intensive recirculating aquaculture systems the use of supplemental oxygen, specifically pure liquid oxygen, increases the mass of fish that can be supported and eliminates oxygen as a major limiting factor to a systems carrying capacity. The use of pure oxygen in a recirculating aquaculture sys...
Coastal zone management in Canada
Peter Harrison; J. G. Michael Parkes
Canada has one of the world's most extensive fresh?water and salt?water shorelines. Management of this extensive coastal zone is the responsibility of a large number of federal and provincial agencies. This article introduces the special issue on Canada by outlining some of the principles of coastal zone management which have emerged, and by identifying key policy questions for the futureespecially
Development and design of a fluidized bed/upflow sand filter configuration for use in recirculating aquaculture systems
Burden, D.G.
A fluidized bed/upflow sand filter configuration, was developed and designed for utilization in recirculating aquaculture system, specifically the soft-shell crab and soft-shell crawfish industries. These filters were selected and designed because of their ability to withstand clogging and still maintain high levels of water quality for aquaculture production. The effectiveness of sand grain size was used to evaluate fluidized bed filter performance with filter loadings ranging from 16 to 1285 pounds of crawfish per cubic foot of filter sand. A coarse sand grain size was recommended as a filter media because of it's ability to shear excessive biofilm growth from the and, thus prohibiting clogging from occurring within the filter bed. The fluidized bed/upflow sand filter combination was evaluated in terms of nitrification and oxygen consumption when used with a recirculating crab shedding system. The filter combination's carrying capacity (700 crabs per cubic foot of sand media) exceeded that observed with the submerged rock filter by more than 20 times and was largely explained by the filter's solids removal ability which significantly reduced the filter's oxygen loading rate (OLR). Nitrification rates with the filter combination were extremely high as total ammonia and nitrite levels remained below 1.0 mg-N/l. Verification of a volumetric loading criteria (150 pounds per cubic foot) for this filter combination was further established with performance data obtained from a commercial soft-shell crawfish facility. Water quality monitoring results indicated that the filters maintained total ammonia and nitrite levels below 1.0 mg-N/l under typical operating conditions. Shock loading, pH control, and over-feeding, rather than filter capacity, dominated water quality fluctuations, thereby indicating that the loading criteria was sufficient for commercial operation.
Breathing of a coral cay: Tracing tidally driven seawater recirculation in permeable coral reef sediments
NASA Astrophysics Data System (ADS)
Santos, Isaac R.; Erler, Dirk; Tait, Douglas; Eyre, Bradley D.
Coral reefs are characterized by high gross productivity in spite of low nutrient concentrations. This apparent paradox may be partially reconciled if seawater recirculation in permeable sediments over large (meters) and long (hours to days) scales is an important source of recycled nitrogen and phosphorus to coral reefs. In this paper we use radon (222Rn, a natural tracer) to quantify tidally driven pore water (or groundwater) exchange between (1) an offshore coral cay island and its fringing reef lagoon and (2) a reef lagoon and the surrounding ocean. As seawater infiltrates Heron Island at high tide, it acquires a radon signal that can be detected when pore waters emerge from carbonate sands at low tide. A nonsteady state model indicated that vertical pore water upwelling rates (or saline submarine groundwater discharge) were >40 cm/d within the reef lagoon and >100 cm/d outside the lagoon at low tide. Within the lagoon, tidal pumping and temperature-driven convection were the main driving forces of pore water advection. At low tide, the reef lagoon level is about 1 m higher than the surrounding ocean. As a result, a steep hydraulic gradient develops at the reef edge, driving unidirectional filtration through the reef framework. Groundwaters were highly enriched in nitrate (average of 530 ?mol, likely influenced by bird guano) relative to lagoon waters (1.9 ?mol). Rough but conservative estimates indicated that groundwater-derived nitrate fluxes (7.9 mmol/m2/d) can replace the entire lagoon nitrate inventory every <19 days. We speculate that as offshore coral islands "breath" (inhale seawater at high tide and exhale groundwater at low tide), they release nutrients that lead to sustained productivity within coral reefs.
Effectiveness of Low Emission Zones: Large Scale Analysis of Changes in Environmental NO2, NO and NOx Concentrations in 17 German Cities
Morfeld, Peter; Groneberg, David A.; Spallek, Michael F.
Background Low Emission Zones (LEZs) are areas where the most polluting vehicles are restricted from entering. The effectiveness of LEZs to lower ambient exposures is under debate. This study focused on LEZs that restricted cars of Euro 1 standard without appropriate retrofitting systems from entering and estimated LEZ effects on NO2, NO, and NOx (?=?NO2+NO). Methods Continuous half-hour and diffuse sampler 4-week average NO2, NO, and NOx concentrations measured inside and outside LEZs in 17 German cities of 6 federal states (20052009) were analysed as matched quadruplets (two pairs of simultaneously measured index values inside LEZ and reference values outside LEZ, one pair measured before and one after introducing LEZs with time differences that equal multiples of 364 days) by multiple linear and log-linear fixed-effects regression modelling (covariables: e.g., wind velocity, amount of precipitation, height of inversion base, school holidays, truck-free periods). Additionally, the continuous half-hour data was collapsed into 4-week averages and pooled with the diffuse sampler data to perform joint analysis. Results More than 3,000,000 quadruplets of continuous measurements (half-hour averages) were identified at 38 index and 45 reference stations. Pooling with diffuse sampler data from 15 index and 10 reference stations lead to more than 4,000 quadruplets for joint analyses of 4-week averages. Mean LEZ effects on NO2, NO, and NOx concentrations (reductions) were estimated to be at most ?2 çg/m3 (or ?4%). The 4-week averages of NO2 concentrations at index stations after LEZ introduction were 55 çg/m3 (median and mean values) or 82 çg/m3 (95th percentile). Conclusions This is the first study investigating comprehensively the effectiveness of LEZs to reduce NO2, NO, and NOx concentrations controlling for most relevant potential confounders. Our analyses indicate that there is a statistically significant, but rather small reduction of NO2, NO, and NOx concentrations associated with LEZs. PMID:25115911
Microbial community distribution and extracellular enzyme activities in leach bed reactor treating food waste: effect of different leachate recirculation practices.
Xu, Su Yun; Karthikeyan, Obuli P; Selvam, Ammaiyappan; Wong, Jonathan W C
This study aimed at understanding the relationship between microbial community and extracellular enzyme activities of leach bed reactor (LBR) treating food waste under different leachate recirculation practices (once per day and continuous) and liquid to solid (L/S) ratios (1:1 and 0.5:1). Microbial community analysis using PCR-DGGE revealed that Lactobacillus sp., Bifidobacter sp., and Proteobacteria were the most abundant species. Number of phylotypes was higher in LBRs with intermittent recirculation; whereas, lower number of phylotypes dominated by the key players of degradation was observed with continuous recirculation. The L/S ratio of 1:1 significantly enhanced the volatile solids removal compared with 0.5:1; however, this effect was insignificant under once a day leachate recirculation. Continuous leachate recirculation with 1:1 L/S ratio significantly improved the organic leaching (240 g COD/kgvolatile solid) and showed distinct extracellular enzyme activities suitable for food waste acidogenesis. PMID:24972915
Rupture Dynamics With Energy Loss Outside the Slip Zone
D. J. Andrews
Energy loss in a damage zone outside the slip zone contributes to fracture energy. Because the thickness of the damage zone increases with rupture propagation distance, fracture energy increases with earthquake size. A rupture front propagating near its limiting velocity has a stress concentration with large shear components at orientations different from that of the slip zone. These components can
Next Generation Pressurized Oxy-Coal Combustion: High Efficiency and No Flue Gas Recirculation
Rue, David
The Gas Technology Institute (GTI) has developed a pressurized oxy-coal fired molten bed boiler (MBB) concept, in which coal and oxygen are fired directly into a bed of molten coal slag through burners located on the bottom of the boiler and fired upward. Circulation of heat by the molten slag eliminates the need for a flue gas recirculation loop and provides excellent heat transfer to steam tubes in the boiler walls. Advantages of the MBB technology over other boilers include higher efficiency (from eliminating flue gas recirculation), a smaller and less expensive boiler, modular design leading to direct scalability, decreased fines carryover and handling costs, smaller exhaust duct size, and smaller emissions control equipment sizes. The objective of this project was to conduct techno-economic analyses and an engineering design of the MBB project and to support this work with thermodynamic analyses and oxy-coal burner testing. Techno-economic analyses of GTIs pressurized oxy-coal fired MBB technology found that the overall plant with compressed CO2 has an efficiency of 31.6%. This is a significant increase over calculated 29.2% efficiency of first generation oxy-coal plants. Cost of electricity (COE) for the pressurized MBB supercritical steam power plant with CO2 capture and compression was calculated to be 134% of the COE for an air-coal supercritical steam power plant with no CO2 capture. This compares positively with a calculated COE for first generation oxy-coal supercritical steam power plants with CO2 capture and compression of 164%. The COE for the MBB power plant is found to meet the U.S. Department of Energy (DOE) target of 135%, before any plant optimization. The MBB power plant was also determined to be simpler than other oxy-coal power plants with a 17% lower capital cost. No other known combustion technology can produce higher efficiencies or lower COE when CO2 capture and compression are included. A thermodynamic enthalpy and exergy analysis found a number of modifications and adjustments that could provide higher efficiency and better use of available work. Conclusions from this analysis will help guide the analyses and CFD modeling in future process development. The MBB technology has the potential to be a disruptive technology that will enable coal combustion power plants to be built and operated in a cost effective way, cleanly with no carbon dioxide emissions. A large amount of work is needed to quantify and confirm the great promise of the MBB technology. A Phase 2 proposal was submitted to DOE and other sponsors to address the most critical MBB process technical gaps. The Phase 2 proposal was not accepted for current DOE support.
SELECTIVE NOx RECIRCULATION FOR STATIONARY LEAN-BURN NATURAL GAS ENGINES
Nigel Clark; Gregory Thompson; Richard Atkinson; Chamila Tissera; Matt Swartz; Emre Tatli; Ramprabhu Vellaisamy
The research program conducted at the West Virginia University Engine and Emissions Research Laboratory (EERL) is working towards the verification and optimization of an approach to remove nitric oxides from the exhaust gas of lean burn natural gas engines. This project was sponsored by the US Department of Energy, National Energy Technology Laboratory (NETL) under contract number: DE-FC26-02NT41608. Selective NOx Recirculation (SNR) involves three main steps. First, NOx is adsorbed from the exhaust stream, followed by periodic desorption from the aftertreatment medium. Finally the desorbed NOx is passed back into the intake air stream and fed into the engine, where a percentage of the NOx is decomposed. This reporting period focuses on the NOx decomposition capability in the combustion process. Although researchers have demonstrated NOx reduction with SNR in other contexts, the proposed program is needed to further understand the process as it applies to lean burn natural gas engines. SNR is in support of the Department of Energy goal of enabling future use of environmentally acceptable reciprocating natural gas engines through NOx reduction under 0.1 g/bhp-hr. The study of decomposition of oxides of nitrogen (NOx) during combustion in the cylinder was conducted on a 1993 Cummins L10G 240 hp lean burn natural gas engine. The engine was operated at different air/fuel ratios, and at a speed of 800 rpm to mimic a larger bore engine. A full scale dilution tunnel and analyzers capable of measuring NOx, CO{sub 2}, CO, HC concentrations were used to characterize the exhaust gas. Commercially available nitric oxide (NO) was used to mimic the NOx stream from the desorption process through a mass flow controller and an injection nozzle. The same quantity of NOx was injected into the intake and exhaust line of the engine for 20 seconds at various steady state engine operating points. NOx decomposition rates were obtained by averaging the peak values at each set point minus the baseline and finding the ratio between the injected NO amounts. It was observed that the air/fuel ratio, injected NO quantity and engine operating points affected the NOx decomposition rates of the natural gas engine. A highest NOx decomposition rate of 27% was measured from this engine. A separate exploratory tests conducted with a gasoline engine with a low air/fuel ratio yielded results that suggested, that high NOx decomposition rates may be possible if a normally lean burn engine were operated at conditions closer to stoichiometric, with high exhaust gas recirculation (EGR) for a brief period of time during the NOx decomposition phase and with a wider range of air/fuel ratios. Chemical kinetic model predictions using CHEMKIN were performed to relate the experimental data with the established rate and equilibrium models. NOx decomposition rates from 35% to 42% were estimated using the CHEMKIN software. This provided insight on how to maximize NOx decomposition rates for a large bore engine. In the future, the modeling will be used to examine the effect of higher NO{sub 2}/NO ratios that are associated with lower speed and larger bore lean burn operation.
Theory of laser phase noise in recirculating fiber-optic delay lines
Moshe Tur; Behzad Moslehi; J. Goodman
Optically driven recirculating delay lines, often used in fiber-optic signal processors, convert the source phase noise to spectrally structured intensity noise at the loop output. This spectrum is characterized by deep notches at zero frequency as well as at other multiples of 1\\/(loop delay). An expression is derived for the power spectral density of the output noise. The formulae obtained,
Wind tunnel simulation on re-circulation of air-cooled condensers of a power plant
Zhifu Gu; Hui Li; Wenhong Zhang; Yan Li; Jiye Peng
The criteria as well as the methods and measurements of wind tunnel simulation on wind effects on air-cooled condensers in a power plant were discussed. The parameter of re-circulation was suggested to describe the wind effects on the efficiency of the condenser. The result of practical project models shows that great wind effects of both wind speed and the angle
Technology Transfer Automated Retrieval System (TEKTRAN)
Recirculating aquaculture systems (RAS,) for both commercial and experimental uses, has been under development in many parts of the world in response to several driving forces. With regards to sites for coastal aquaculture, the scarcity of affordable land has driven aquaculture endeavors for marine ...
Geosmin causes off-flavour in arctic charr in recirculating aquaculture systems
Technology Transfer Automated Retrieval System (TEKTRAN)
The earthy and muddy off-flavors in pond-reared fish are due to the presence of geosmin or 2-methylisoborneol (MIB) in the flesh of the fish. Similar off-flavors have been reported in fish raised in recirculating aquaculture systems (RAS); however, little information is available regarding the ...
Process requirements for achieving full-flow disinfection of recirculating water using ozonation and UV irradiation
Steven T. Summerfelt; Mark J. Sharrer; Scott M. Tsukuda; Michael Gearheart
A continuous water disinfection process can be used to prevent the introduction and accumulation of obligate and opportunistic fish pathogens in recirculating aquaculture systems (RAS), especially during a disease outbreak when the causative agent would otherwise proliferate within the system. To proactively prevent the accumulation of fish pathogens, ozonation and ultraviolet (UV) irradiation processes have been used separately or in
Quantification of anammox activity in a denitrification reactor for a recirculating aquaculture system
Ori Lahav; Iris Bar Massada; Dimitry Yackoubov; Ruth Zelikson; Noam Mozes; Yossi Tal; Sheldon Tarre
The activity of anammox bacteria in a denitrification reactor in a recirculating aquaculture system (RAS) for gilthead seabream production was investigated. Organic matter, extracted from the pond's solid filter, was used as the electron donor and carbon source for the denitrification reaction. The reactor was operated at four solid retention times (SRT). At steady state, anammox activity showed similar activity
A semi-recirculating, integrated system for the culture of fish and seaweed
Andreas Schuenhoff; Muki Shpigel; Ingrid Lupatsch; Arik Ashkenazi; Flower E Msuya; Amir Neori
Biofiltration allows for environmentally sustainable mariculture. An intensive, biofiltered recirculating integrated system producing fish and seaweed on a semi-commercial scale was evaluated with respect to production and to nutrient and heat budgets. The system consisted of abalone (Haliotis discus hannai) and sea urchin (Paracentrotus lividus) tanks, an intensive fishpond (Sparus aurata), and a three-stage Ulva lactuca biofilter, which cleaned and
Oxygen mass balance in a recirculation aquaculture system for raising European Wels (Silurus glanis L.)
Viktoras Mongirdas; Albinas Kusta
The growth of the European Wels or sheat-fish (Silurus glanis L.) was eva- luated in a recirculation aquaculture system situated in a greenhouse. Recir- culation aquaculture system components were evaluated in terms of oxygen use and generation. Oxygen gradients revealed the main fault of the originally constructed system elements - mechanical and biological filters. The influen- ce of organic matter
Systems engineering for ornamental fish production in a recirculating aquaculture system
Ilan Halachmi
The aim was to develop a simulation model for determining the optimal layout and management regime for ornamental fish recirculating aquaculture system (ORAS). The work plan involved: (1) quantifying the effects of fish growth rates, the nature of the products, and the management practices; (2) developing a mathematical simulation model of the ORAS, taking into account all factors that directly
A study on the optimal hydraulic loading rate and plant ratios in recirculation aquaponic system
Azizah Endut; A. Jusoh; N. Ali; W. B. Wan Nik; A. Hassan
The growths of the African catfish (Clarias gariepinus) and water spinach (Ipomoea aquatica) were evaluated in recirculation aquaponic system (RAS). Fish production performance, plant growth and nutrient removal were measured and their dependence on hydraulic loading rate (HLR) was assessed. Fish production did not differ significantly between hydraulic loading rates. In contrast to the fish production, the water spinach yield
Using computer spreadsheets for water flow and biofilter sizing in recirculating aquaculture production systems
Thomas M Losordo; Alexander O Hobbs
North Carolina State University has been active in the development, evaluation and demonstration of recirculating aquaculture technology since 1989. In the process, numerous engineering and economic spreadsheets (worksheets) have been developed to assist in the design and analysis of these systems. The spreadsheet described in this paper is based on a set of mass balance equations developed and described by
Ozonation of a recirculating rainbow trout culture system II. Effects on microscreen filtration and water quality
Steven T. Summerfelt; Joseph A. Hankins; Amy L. Weber; Martin D. Durant
Ozone was added to water in a recirculating rainbow trout (Oncorhynchus mykiss) culture system just prior to the culture tanks in order to oxidize nitrite and organic material, improve overall water quality, and assist removal of solids across the microscreen filter. Data from four 8-week studies on ozonation and an 8-week no ozone control indicated that adding ozone reduced the
The use of ozone in a high density recirculation system for rotifers
G Suantika; P Dhert; G Rombaut; J Vandenberghe; T De Wolf; P Sorgeloos
The use of ozone in the effluent treatment of a closed recirculation system for rotifers resulted in a significant improvement of rotifer production and water quality. Compared to a control treatment, the rotifer culture exposed to ozone did not only support a higher rotifer biomass (16000 vs. 8000 rotifers ml?1), it also allowed a prolongation of the culture period for
Recirculating pump seal investigation. Volume 2. Technical planning study TPS-76-626. Final report. [BWR
A review of the BWR recirculation pump seals was conducted as the first step in the possible development of a new pump seal with improved sealing capability and service life. The first task of this study was the identification of the major seal failure mechanisms. A new seal specification was written. Existing seal designs were then investigated. The fourth task
Flow, aeration, and carbon dioxide transfer rates for airlifts used in recirculating aquaculture systems
Technology Transfer Automated Retrieval System (TEKTRAN)
Airlift pumping systems reduce the electrical costs of moving water in a recirculating aquaculture system and can be concurrently designed to aerate water and remove carbon dioxide. This study determined the water flow, oxygen transfer, and CO2 removal rates for water using airlift technology in a 1...
Molecular Determinants Controlling Homeostatic Recirculation and Tissue-Specific Trafficking of Lymphocytes
Toshiyuki Tanaka; Yukihiko Ebisuno; Naotoshi Kanemitsu; Eiji Umemoto; Bo-gie Yang; Myoung-ho Jang; Masayuki Miyasaka
The homeostasis of the immune system is maintained by the recirculation of naÿve lymphocytes through the secondary lymphoid tissues, such as the lymph nodes, Peyers patches, and spleen. Upon insult by pathogens or antigens, lymphocytes become activated, and the regulated trafficking of these cells results in the integration of systemic and regional immune responses. The exquisite specificity of such lymphocyte
On thermoelectric power conversion from heat re-circulating combustion systems F. J. Weinberg
On thermoelectric power conversion from heat re-circulating combustion systems F. J. Weinberg Fax: 4420 7594 5604 Word count: 3750 Diags. equivalent: 1600 5350 #12;On thermoelectric power the absolute maximum efficiency of energy conversion by thermoelectric devices that operate as part of the heat
A novel computer simulation model for design and management of re-circulating aquaculture systems
Ilan Halachmi; Yitzchak Simon; Rami Guetta; Eric M. Hallerman
The aim of this study was to develop a simulation model for finding the optimal layout and management regime for a re-circulating aquaculture system (RAS). The work plan involved: (1) quantifying the effects of fish growth and management practices on production; (2) developing a mathematical simulation model for the RAS, taking into account all factors that directly influence system profitability;
Process Requirements for Achieving Full-Flow Disinfection of Recirculating Water Using Ozonation and UV Irradiation
Technology Transfer Automated Retrieval System (TEKTRAN)
A continuous water disinfection process can be used to prevent the introduction and accumulation of obligate and opportunistic fish pathogens in recirculating aquaculture systems (RAS), especially during a disease outbreak when the causative agent would otherwise proliferate within the system. To p...
Recirculation injection by nonlinear gating for high-power laser pulses
NASA Astrophysics Data System (ADS)
Jovanovic, Igor; Shverdin, Miro; Gibson, David; Brown, Curtis
The average power and efficiency of processes that exhibit low interaction cross section and low optical loss can often be enhanced by recirculating the laser pulse in the cavity. Inverse Compton scattering of the photon pulse on an electron bunch, harmonic generation, and spectroscopy represent examples of such processes. Methods for laser recirculation that enhance the interaction efficiency have been proposed in the past, based on resonant cavity coupling, intracavity amplification, or electro-optical switching. Those methods exhibit limitations such as interferometric alignment accuracies, complexity, and nonlinear phase accumulation. A novel scheme for energetic short laser pulse recirculation, termed recirculation injection by nonlinear gating (RING), is described. RING is based on intracavity nonlinear frequency conversion for optical switching, does not exhibit interferometric alignment constraints, and is scalable to extreme peak power. Initial demonstration of the RING technique is presented at a 1-mJ level, with cavity enhancement factors exceeding 25 in a simple unstable resonator cavity. Applications of the RING technique in biomedical and other applications are outlined.
Tissue engineering of human cartilage and osteochondral composites using recirculation bioreactors
Nastaran Mahmoudifar; Pauline M. Doran
Chondrocytes isolated from human foetal epiphyseal cartilage were seeded dynamically into polyglycolic acid (PGA) scaffolds and cultured in recirculation column bioreactors to produce tissue-engineered cartilage. Several culture techniques with the potential to provide endogenous growth factors and other conditions beneficial for de novo cartilage synthesis were investigated. Osteochondral composite constructs were generated by seeding separate PGA scaffolds with either foetal
Molecular Adsorbents Recirculating System in Patients with Severe Liver Failure. Experience of a Single Romanian Centre
Elena-Emanuela Rusu; Mihai Voiculescu; Diana-Silvia Zilisteanu; Gener Ismail
Aim: This is a retrospective, observational study regarding the experience of the Fundeni Clinical Institute in the application of the Molecular Adsorbents Recirculating System in patients with liver failure. Method: From January 2002 until December 2007, we performed 50 MARS sessions in 27 patients, mean age 38.96 Ý 19.58 years. The etiology of liver failure was as follows: acute liver
Disinfection of water in recirculating aquaculture systems with peracetic acid (PAA)
Technology Transfer Automated Retrieval System (TEKTRAN)
The disinfection behaviour of peracetic acid (PAA) in recirculating aquaculture systems (RAS) was investigated. Peracetic acid is a strong oxidizing agent found in various concentrations in different products. Three Wofasteril PAA products (E400 (c), Lspecical; AC 150) were tested in vitro for the...
Design and Evaluation of Recirculating Water Systems for Maintenance and Propagation of Freshwater Mussels
William F. Henley; Lora L. Zimmerman; Richard J. Neves; Mark R. Kidd
A complete system for culturing, rearing, and holding juvenile and adult freshwater mussels (Unionidae) was designed and evaluated for use at hatcheries and research facilities. The system includes air delivery, water conditioning and delivery, algal culturing and automated algal feed delivery, and air-driven water-recirculating units. These systems are appropriate for holding and conditioning adult mussels for spawning, as well as
Longitudinal BBU Threshold Current in Recirculating Linacs Changsheng Song and Georg H. Hoffstaetter
Hoffstaetter, Georg
Breakup Instability When an electron bunch passes through an RF cavity, it can excite both transverse and longitudinal HOMs. Previous papers have described how the recirculation of electron bunches can cause to the transverse case, longitudinal HOMs excited by electron bunches can lead to the longitudinal BBU instability
Electron recirculation in electrostatic multicusp systems: II. System performance scaling of one-dimensional rollover wells
R. W. Bussard; K. E. King
In an earlier paper a comprehensive study was made of the recirculation and losses of electrons in their flow through simple inverse power-law potential wells bounded by similarly inverse power-law dependent magnetic fields. This study examined electron flow and loss behavior in the simplest approximation invoked to describe Polywell confinement systems. The importance of this study, and of the present
Highly selective Microwave Photonic filters based on new FBGs-EDF recirculating cavities and tuned modulators
Beatriz Ortega; JosÕ Mora; JosÕ Capmany; Daniel Pastor; Raimundo GarcÚa-Olcina; Salvador Sales
We present a microwave photonic filter featuring the highest Q ever reported The filter structure is based on a modified gratings and Erbium Doped Fiber based structure. Q factors over 3000 are demonstrated when a tuned modulator is used in combination with the recirculating approach. Also comb RF filters for specific applications have been implemented. Finally, we investigate the possibility
Suction-recirculation device for stabilizing particle flows within a solar powered solid particle receiver
Kolb, Gregory J. (Albuquerque, NM)
A suction-recirculation device for stabilizing the flow of a curtain of blackened heat absorption particles falling inside of a solar receiver with an open aperture. The curtain of particles absorbs the concentrated heat from a solar mirror array reflected up to the receiver on a solar power tower. External winds entering the receiver at an oblique angle can destabilize the particle curtain and eject particles. A fan and ductwork is located behind the back wall of the receiver and sucks air out through an array of small holes in the back wall. Any entrained particles are separated out by a conventional cyclone device. Then, the air is recirculated back to the top of the receiver by injecting the recycled air through an array of small holes in the receiver's ceiling and upper aperture front wall. Since internal air is recirculated, heat losses are minimized and high receiver efficiency is maintained. Suction-recirculation velocities in the range of 1-5 m/s are sufficient to stabilize the particle curtain against external wind speeds in excess of 10 m/s.
Identification of optimum potassium nutrition of greenhouse plants grown in recirculating subirrigation
Blessington, Trisha R.
. Experiment 3 compared the optimum K fertilizer rates of vinca 'Pacifica Red' grown in recirculating subirrigation and top water. The plants grew the best in subirrigation at 2 mM K and in top water at 4 mM K. Fertilizer salt stratification occurred...
Analysis of non-adiabatic heat-recirculating combustors Paul D. Ronney
: Ronney, P. D., "Analysis of non-adiabatic heat-recirculating combustors," Combustion and Flame, Vol. 135 a small effect of conduction along this surface leads to significantly higher minimum M. Comparison configuration provides superior performance under similar operating conditions. Implications for microscale
Low-dose hydrogen peroxide application in closed recirculating aquaculture systems
Technology Transfer Automated Retrieval System (TEKTRAN)
The aim of the present work was to simulate water treatment practice with hydrogen peroxide (HP) in recirculating aquaculture systems (RAS). Six identical 1700 L pilot scale RAS were divided into two experimental groups based on daily feed allocation and were operated under constant conditions durin...
On-Line Measurement and Tuning of Multi-Pass Recirculation Time in the CEBAF Linacs
or slippage of the beam arrival time relative to the RF phase will natu- rally change the beam energy on target. This paper deals with detection and correction of drifts in the beam path length which cause Variations in the beam energy and orbit are detected in the recirculation arcs and in the experimental halls
Effect of exhaust gas recirculation (EGR) contamination of diesel engine oil on wear
S. Aldajah; O. O. Ajayi; G. R. Fenske; I. L. Goldblatt
Exhaust gas recirculation (EGR) is one of the effective means to reduce the NOX emission from diesel engines. Returning exhaust product to the diesel engine combustion chamber accelerated the degradation of the lubricant engine oil, primarily by increasing the total acid number (TAN) as well as the soot content and, consequently, the viscosity. These oil degradation mechanisms were observed in
Electronic fuel supply control system for internal combustion engines, having exhaust gas recirculation control
A. Yamato; S. Umesaki
In an electronic fuel supply control system for an internal combustion engines, the fuel quantity being supplied to the engine is set to different values in accordance with the operating condition of the engine, between when the exhaust gas recirculation is operated and when it is not operated, for achieving proper air\\/fuel ratios. Further, immediately after a valve lift command
Air Charge Control for Turbocharged Spark Ignition Engines with Internal Exhaust Gas Recirculation
Stefanopoulou, Anna
Air Charge Control for Turbocharged Spark Ignition Engines with Internal Exhaust Gas Recirculation of transient cylin- der charge control, based on a cycle-averaged mean-value model for a turbocharged spark) in the drivability of a turbocharged Spark Ignition Direct Injection (SIDI) engine equipped with dual cam phasing
Gas transfer rates from airlifts used for concurrent aeration, carbon dioxide stripping, and recirculation
Technology Transfer Automated Retrieval System (TEKTRAN)
Airlifts simplify recirculating aquaculture systems and can potentially reduce capital costs and minimize maintenance issues. Airlifts have the ability to move and aerate water as well as degass the water of any carbon dioxide. This study evaluated the oxygen transfer and carbon dioxide removal abil...
Applying rotary jet heads for mixing and mass transfer in a forced recirculation tank reactor system
Mikkel Nordkvist; Thomas GrotkjÌr; Jan S. Hummer; John Villadsen
An approximation to an ideally mixed tank reactor can be obtained by vigorous stirring with mechanical mixers. For an aerated reactor the gas dispersion contributes to the mixing process. Mixing can also be achieved by recirculation of a portion of the liquid through either an internal or an external loop.In this study, we determine mixing times in water and CMC
Effect of recirculation and initial concentration of microorganisms on the disinfection kinetics of Escherichia coli
J. J. VÕlez-Colmenares; A. Acevedo; E. Nebot
Disinfection studies with two pure strains of Escherichia coli ATCC 11229 and ATCC 15597 and real municipal wastewater were carried out at laboratory scale with a 10W low pressure ultraviolet lamp in an ultraviolet (UV) disinfection system with recirculation of the liquid. A double first order kinetic model was established to fit the ultraviolet disinfection curves for the two microorganisms.
Solids removal from a coldwater recirculating system - comparison of swirl separator and radial-flow settlers
Technology Transfer Automated Retrieval System (TEKTRAN)
Solids removal across two settling devices, i.e., a swirl separator and a radial-flow settler, and across a microscreen drum filter was evaluated in a fully recirculating system containing a single 150 m3 'Cornell-type' dual-drain tank during the production of food-size Arctic char and rainbow trout...
Improvement of anaerobic digester performance by wastewater recirculation through an aerated membrane.
Technology Transfer Automated Retrieval System (TEKTRAN)
Swine wastewater from an anaerobic digester was recirculated through a silicone hose located in an external aeration chamber to determine its effect on wastewater malodorants and biogas composition. The silicone hose acted as a semipermeable membrane for the passage of small molecules. In the first...
Observations on side-swimming rainbow trout Oncorhynchus mykiss in water recirculation aquaculture systems
Technology Transfer Automated Retrieval System (TEKTRAN)
During a controlled 6-month study using six replicated water recirculation aquaculture systems (WRAS), it was observed that rainbow trout Oncorhynchus mykiss in all WRAS exhibited a higher-than-normal prevalence of side-swimming (i.e. controlled, forward swimming, but with misaligned orientation suc...
Membrane biological reactor treatment of a saline backwash flow from a recirculating aquaculture system
Technology Transfer Automated Retrieval System (TEKTRAN)
A recirculating aquaculture system (RAS) can minimize water use, allowing fish production in regions where water is scarce and also placing the waterborne wastes into a concentrated and relatively small volume of effluent. The RAS effluent generated during clarifier backwash is usually small in vol...
Performance of Water Recirculation Loop Maintentance Components for the Advanced Spacesuit Water Membrane Evaporator
NASA Technical Reports Server (NTRS)
Rector, Tony; Peyton, Barbara; Steele, John W.; Bue, Grant C.; Campbell, Colin; Makinen, Janice
Water loop maintenance components to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop have undergone a comparative performance evaluation with a second SWME water recirculation loop with no water quality maintenance. Results show the benefits of periodic water maintenance. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing Sublimator technology. The driver for the evaluation of water recirculation maintenance components was to further enhance this advantage through the leveraging of fluid loop management lessonslearned from the International Space Station (ISS). A bed design that was developed for a UTAS military application, and considered for a potential ISS application with the Urine Processor Assembly, provided a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The maintenance cycle included the use of a biocide delivery component developed for ISS to introduce a biocide in a microgravity-compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware.
Performance of Water Recirculation Loop Maintenance Components for the Advanced Spacesuit Water Membrane Evaporator
NASA Technical Reports Server (NTRS)
Rector, Tony; Peyton, Barbara M.; Steele, John W.; Makinen, Janice; Bue, Grant C.; Campbell, Colin
Water loop maintenance components to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop have undergone a comparative performance evaluation with a second SWME water recirculation loop with no water quality maintenance. Results show the benefits of periodic water maintenance. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing Sublimator technology. The driver for the evaluation of water recirculation maintenance components was to further enhance this advantage through the leveraging of fluid loop management lessons learned from the International Space Station (ISS). A bed design that was developed for a UTAS military application, and considered for a potential ISS application with the Urine Processor Assembly, provided a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The maintenance cycle included the use of a biocide delivery component developed for ISS to introduce a biocide in a microgravity compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware.
Temperate Oceans : Light Zones
NSDL National Science Digital Library
This reference provides an overview of the three zones into which the ocean can be divided based on the amount of light recieved: the sunlit (or euphotic) zone, the twilight (or disphotic) zone, and the midnight (or aphotic) zone. The descriptions are accompanied by diagrams and a brief listing of the organisms that live in each zone.
NASA Technical Reports Server (NTRS)
NASA's QuikSCAT satellite has confirmed a 30-year old largely unproven theory that there are two areas near the equator where the winds converge year after year and drive ocean circulation south of the equator. By analyzing winds, QuikSCAT has found a year-round southern and northern Intertropical Convergence Zone. This find is important to climate modelers and weather forecasters because it provides more detail on how the oceans and atmosphere interact near the equator. The Intertropical Convergence Zone (ITCZ) is the region that circles the Earth near the equator, where the trade winds of both the Northern and Southern Hemispheres come together. North of the equator, strong sun and warm water of the equator heats the air in the ITCZ, drawing air in from north and south and causing the air to rise. As the air rises it cools, releasing the accumulated moisture in an almost perpetual series of thunderstorms. Satellite data, however, has confirmed that there is an ITCZ north of the equator and a parallel ITCZ south of the equator. Variation in the location of the ITCZ is important to people around the world because it affects the north-south atmospheric circulation, which redistributes energy. It drastically affects rainfall in many equatorial nations, resulting in the wet and dry seasons of the tropics rather than the cold and warm seasons of higher latitudes. Longer term changes in the ITCZ can result in severe droughts or flooding in nearby areas. 'The double ITCZ is usually only identified in the Pacific and Atlantic Oceans on a limited and seasonal basis,' said Timothy Liu, of NASA's Jet Propulsion Laboratory and California Institute of Technology, Pasadena, Calif., and lead researcher on the project. In the eastern Pacific Ocean, the southern ITCZ is usually seen springtime. In the western Atlantic Ocean, the southern ITCZ was recently clearly identified only in the summertime. However, QuikSCAT's wind data has seen the southern ITCZ in all seasons across the entire Atlantic Ocean and the eastern Pacific. 'QuikSCAT's wind data confirms there is a double ITCZ, and that they exist all year long,' Liu said. This is a major find for the science community, as the existence, location, and seasonality of the double ITCZ had remained controversial since 1969. full text: Satellite Sees Double Zones of Converging Tropical Winds around The World For more about convergence zones, read: The Intertropical Convergence Zone and Convergence Zones: Where the Action Is Image courtesy Liu and Xie, NASA JPL
NSDL National Science Digital Library
Katie Hale (California State University, Fullerton; Student, Biological Sciences)
The middle intertidal zone is submerged during high tide and only exposed during low tides. This zone has the most moderate conditions of the zones and has many algae, sea anemones, mollusks, and crustaceans.
NSDL National Science Digital Library
Katie Hale (California State University, Fullerton; Student, Biological Sciences)
The upper intertidal zone is exposed most of the time and will become submerged only during high tide. This zone is least abundant of the intertidal zones but contains some mollusks, barnacles, and other animals adapted to avoid drying out.
NSDL National Science Digital Library
Katie Hale (California State University, Fullerton; Student, Biological Sciences)
The bottom intertidal area remains under water except during low tides. This zone is most abundant of the intertidal zones and contains seaweeds and other plants, invertebrates, and fishes. The bottom zone is subject to the most intense wave action.
NSDL National Science Digital Library
Katie Hale (CSUF; Biological Sciences)
The bottom intertidal area remains under water except during low tides. This zone is most abundant of the intertidal zones and contains seaweeds and other plants, invertebrates, and fishes. The bottom zone is subject to the most intense wave action.
NSDL National Science Digital Library
Katie Hale (CSUF; Biological Sciences)
The upper intertidal zone is exposed most of the time and will become submerged only during high tide. This zone is least abundant of the intertidal zones but contains some mollusks, barnacles, and other animals adapted to avoid drying out.
NSDL National Science Digital Library
Katie Hale (CSUF; Biological Sciences)
The middle intertidal zone is submerged during high tide and only exposed during low tides. This zone has the most moderate conditions of the zones and has many algae, sea anemones, mollusks, and crustaceans.
Influence of sulfate-reducing bacteria and thiogenic bacteria on corrosion of carbon steel in refinery recirculating water systems
Teslya, B.M.; Chupareva, I.E.; Burlov, V.V.
The influence of SRB and TB on the kinetics of carbon steel corrosion was investigated in recirculating water at the Kirishi refinery and in cumulative cultures of the SRB and TB obtained by inoculating elective nutrient media with the recirculating water (300 ml of water per 1000 ml of medium). The concentrations of SRB and TB in the recirculating water and in the cumulative cultures were determined by the serial dilution method. The corrosion activity of the microorganisms was evaluated on the basis of carbon steel specimen corrosion rates under dynamic and static conditions.
Root Apex Transition Zone As Oscillatory Zone
Baluka, Frantiek; Mancuso, Stefano
Root apex of higher plants shows very high sensitivity to environmental stimuli. The root cap acts as the most prominent plant sensory organ; sensing diverse physical parameters such as gravity, light, humidity, oxygen, and critical inorganic nutrients. However, the motoric responses to these stimuli are accomplished in the elongation region. This spatial discrepancy was solved when we have discovered and characterized the transition zone which is interpolated between the apical meristem and the subapical elongation zone. Cells of this zone are very active in the cytoskeletal rearrangements, endocytosis and endocytic vesicle recycling, as well as in electric activities. Here we discuss the oscillatory nature of the transition zone which, together with several other features of this zone, suggest that it acts as some kind of command center. In accordance with the early proposal of Charles and Francis Darwin, cells of this root zone receive sensory information from the root cap and instruct the motoric responses of cells in the elongation zone. PMID:24106493
Zoning, equity, and public health.
Maantay, J
Zoning, the most prevalent land use planning tool in the United States, has substantial implications for equity and public health. Zoning determines where various categories of land use may go, thereby influencing the location of resulting environmental and health impacts. Industrially zoned areas permit noxious land uses and typically carry higher environmental burdens than other areas. Using New York City as a case study, the author shows that industrial zones have large residential populations within them or nearby. Noxious uses tend to be concentrated in poor and minority industrial neighborhoods because more affluent industrial areas and those with lower minority populations are rezoned for other uses, and industrial zones in poorer neighborhoods are expanded. Zoning policies, therefore, can have adverse impacts on public health and equity. The location of noxious uses and the pollution they generate have ramifications for global public health and equity; these uses have been concentrated in the world's poorer places as well as in poorer places within more affluent countries. Planners, policymakers, and public health professionals must collaborate on a worldwide basis to address these equity, health, and land use planning problems. PMID:11441726
Design and performance characteristics of a low-head recirculating aquaculture tank system for low salinity finfish production
Technology Transfer Automated Retrieval System (TEKTRAN)
Water treatment components of a recirculating aquaculture system (RAS) consist mainly of: solid removal devices, biofiltration, aeration, degassing units, and water distribution. For each component, multiple options are available and the selection is based on system volume, system hydrodynamics, fis...
Future float zone development in industry
NASA Technical Reports Server (NTRS)
Sandfort, R. M.
The present industrial requirements for float zone silicon are summarized. Developments desired by the industry in the future are reported. The five most significant problems faced today by the float zone crystal growth method in industry are discussed. They are economic, large diameter, resistivity uniformity, control of carbon, and swirl defects.
Hexachlorobenzene uptake by fathead minnows and macroinvertebrates in recirculating sediment/water systems
Schuytema, G.S.; Krawczyk, D.F.; Griffis, W.L.; Nebeker, A.V.; Robideaux, M.L.
Fathead minnow (Pimephales promelas), the worm, Lumbriculus variegatus, and the amphipods Hyalella azteca and Gammarus lacustris were exposed to hexachlorobenzene (HCB) in water with and without a bed of HCB-spiked sediment. Water HCB concentrations were maintained by recirculation through HCB-packed columns. Recirculating HCB-bound particulates and possibly eroded HCB particulates were an added source of HCB in addition to the sediment bed. Significant bioaccumulation of HCB in animal tissues was observed in water-only and water-sediment exposures. The presence of the HCB-spiked sediment did not result in a significant increase in the uptake of HCB by the organisms, but there was a substantial increase in sediment HCB levels over time. Higher tissue HCB levels in aquaria without sediment suggest that the sediment was a more efficient sink for HCB than the organisms.
Removal of sodium chloride from human urine via batch recirculation electrodialysis at constant applied voltage
NASA Technical Reports Server (NTRS)
Gordils-Striker, Nilda E.; Colon, Guillermo
The removal of sodium chloride (NaCl) from human urine using a six-compartment electrodialysis cell with batch recirculation mode of operation for use in advanced life support systems (ALSS) was studied. From the results obtained, batch recirculation at constant applied voltage yields high values (approximately 94% of NaCl removal. Based on the results, the initial rate of NaCl removal was correlated to a power function of the applied voltage: -r=2.0 x 10(-4)E(3.8). With impedance spectroscopy methods, it was also found that the anion membranes were more affected by fouling with an increase of the ohmic resistance of almost 11% compared with 7.4% for the cationic ones.
Thermal characterization of an AMTEC recirculating test cell. [Alkali Metal ThermoElectric Converter
NASA Technical Reports Server (NTRS)
Underwood, M. L.; O'Connor, D.; Williams, R. M.; Jeffries-Nakamura, B.; Ryan, M. A.; Bankston, C. P.
An alkali metal thermoelectric converter (AMTEC) recirculating test cell has been operated in order to determine the magnitudes of the primary heat losses of the cell and the value of the emissivity of the condenser surface. The energy balance included radiation losses, conductive losses, and losses due to the flow of sodium into the cell. The radiative heat flux dominated the heat loss mechanism of the cell at open circuit, and the condenser emissivity was calculated to be about 0.1. It is shown that, if this emissivity can be reduced to 0.02, then parasitic losses in an AMTEC recirculating test cell operating near peak power would be less than 40 percent of the heat required by the cell. The condenser emissivity decreases with elapsed time, resulting in improved thermal performance of the cell.
LUX - A recirculating linac-based ultrafast X-ray source
Corlett, J.N.; Barletta, W.A.; DeSantis, S.; Doolittle, L.; Fawley, W.M.; Green, M.A.; Heimann, P.; Leone, S.R.; Lidia, S.; Li, D.; Parmigiani, F.; Ratti, A.; Robinson, K.; Schoenlein, R.; Staples, J.; Wan, W.; Wells, R.; Wilcox, R.; Wolski, A.; Zholents, A.
We describe the design of a proposed source of ultra-fast synchrotron radiation x-ray pulses based on a recirculating superconducting linac, with an integrated array of ultrafast laser systems. The source produces x-ray pulses with duration of 10-50 fs at a 10 kHz repetition rate, with tunability from EUV to hard x-ray regimes, and optimized for the study of ultra-fast dynamics. A high-brightness rf photocathode provides electron bunches. An injector linac accelerates the beam to the 100 MeV range, and is followed by four passes through a 700 MeV recirculating linac. Ultrafast hard x-ray pulses are obtained by a combination of electron bunch manipulation, transverse temporal correlation of the electrons, and x-ray pulse compression. EUV and soft x-ray pulses as short as 10 fs are generated in a harmonic-cascade free electron laser scheme.
Aerobic and Anoxic Growth and Nitrate Removal Capacity of a Marine Denitrifying Bacterium Isolated from a Recirculation Aquaculture System
Maria-Teresa Borges; AndrÕ Sousa; Paolo De Marco; Ana Matos; Petra H—nigovÃ; Paula M. L. Castro
Bacterial biofilters used in marine recirculation aquaculture systems need improvements to enhance nitrogen removal efficiency.\\u000a Relatively little is known about biofilter autochthonous population structure and function. The present study was aimed at\\u000a isolating and characterizing an autochthonous denitrifying bacterium from a marine biofilter installed at a recirculation\\u000a aquaculture system. Colonization of four different media in a marine fish farm was
Human skin is protected by four functionally and phenotypically discrete populations of resident and recirculating memory T cells.
Watanabe, Rei; Gehad, Ahmed; Yang, Chao; Scott, Laura L; Teague, Jessica E; Schlapbach, Christoph; Elco, Christopher P; Huang, Victor; Matos, Tiago R; Kupper, Thomas S; Clark, Rachael A
The skin of an adult human contains about 20 billion memory T cells. Epithelial barrier tissues are infiltrated by a combination of resident and recirculating T cells in mice, but the relative proportions and functional activities of resident versus recirculating T cells have not been evaluated in human skin. We discriminated resident from recirculating T cells in human-engrafted mice and lymphoma patients using alemtuzumab, a medication that depletes recirculating T cells from skin, and then analyzed these T cell populations in healthy human skin. All nonrecirculating resident memory T cells (TRM) expressed CD69, but most were CD4(+), CD103(-), and located in the dermis, in contrast to studies in mice. Both CD4(+) and CD8(+) CD103(+) TRM were enriched in the epidermis, had potent effector functions, and had a limited proliferative capacity compared to CD103(-) TRM. TRM of both types had more potent effector functions than recirculating T cells. We observed two distinct populations of recirculating T cells, CCR7(+)/L-selectin(+) central memory T cells (TCM) and CCR7(+)/L-selectin(-) T cells, which we term migratory memory T cells (TMM). Circulating skin-tropic TMM were intermediate in cytokine production between TCM and effector memory T cells. In patients with cutaneous T cell lymphoma, malignant TCM and TMM induced distinct inflammatory skin lesions, and TMM were depleted more slowly from skin after alemtuzumab, suggesting that TMM may recirculate more slowly. In summary, human skin is protected by four functionally distinct populations of T cells, two resident and two recirculating, with differing territories of migration and distinct functional activities. PMID:25787765
Evaluation of polyhydroxybutyrate as a carbon source for recirculating aquaculture water denitrification
Kelly A. Rusch; Ronald F. Malone
The effect of salinity, dissolved oxygen and NO3-N concentration on the denitrification of recirculating aquaculture water using polyhydroxybutyrate (PHB) was evaluated. Four PHB media with different molecular weights and configurations were tested. The results show that at higher nitrate concentrations in the influent water, the consumed PHB:NO3-N ratio decreased. An average of 2.9 g of PHB:1 g NO3-N removed at
Blue tilapia ( Oreochromis aureus) growth rate in relation to dissolved oxygen concentration under recirculated water conditions
Sofronios E. Papoutsoglou; Gar. Tziha
The growth rate of Oreochromis aureus in relation to dissolved oxygen concentrations (2ñ63Ý0ñ12, 3ñ75Ý0ñ12, 6ñ51Ý0ñ13 ppm or 31ñ3, 44ñ6 and 77ñ5% saturation, respectively) was investigated. Three duplicated populations of 29 specimens (mean initial body weight ?27ñ3 g) were reared in 100-litre tanks for 200 days under recirculated water conditions. Fish were offered an artificial diet three times per day, 6
Water Treatment and Performance Characteristics Evaluation of a Pilot-Scale Recirculating Aquaculture System
Yan Zaisheng; Liu Changfa; Wang Shihe; He Jie; Liu Yuan; Zhang Liyong; Zhang Junxin
To minimize the impact on the environment and land requirements, a pilot-scale recirculating aquaculture system was engineered and investigated in a greenhouse. The system included a three-step particulates separation device, fluidized bed reactors (FBR), UV treatment and cooling. Japanese flounder (Paralichthys olivaceus) were raised from initial mean weight 4.9 plusmn 0.6g to final mean weight 35.8 plusmn 14.6g after 140
Evaluation of submerged surface flow (SSF) constructed wetlands for recirculating tilapia production systems
W ZACHRITZII; A. T. Hanson; J. A. Sauceda; K. M. Fitzsimmons
A recirculating aquaculture system (RAS) treating tilapia production wastewaters used a two-step process combining a simple clarifier and a submerged surface flow (SSF) constructed wetlands for suspended solids removal and removal of nitrogenous compounds. This system successfully supported a commercial scale level of production (>35kg\\/m3) for over 36 months of operation. The innovative SSF wetland design incorporated a high hydraulic
Noise analysis of an amplified fiber-optic recirculating-ring delay line
Jon Thomas Kringlebotn; Kjell Blotekjaer
We present the first theoretical and experimental noise analysis of a fiber-optic recirculating-ring delay line (RDL) including a doped fiber amplifier to compensate for the roundtrip loss. Both thermal-like sources and laser sources are considered. The output source induced noise (signal-signal beat noise), signal-spontaneous (s-sp) beat noise, and spontaneous-spontaneous (sp-sp) beat noise spectra for a thermal-like source are calculated from
Leachate recirculation at the Nanticoke sanitary landfill using a bioreactor trench. Final report
J. J. Pagano; R. J. Scrudato; G. M. Sumner
A one-year landfill leachate recirculation demonstration project was conducted in a 20-acre cell at the Broome County, NY, Nanticoke Landfill using a retrofit bioreactor trench design concept to introduce landfill leachate to the surrounding refuse mass. Over the course of the project, 1.1 million gallons of landfill leachate were distributed through the bioreactor trench, substantially increasing the moisture content (approaching
Selective NOx Recirculation for Stationary Lean-Burn Natural Gas Engines
Nigel N. Clark
Nitric oxide (NO) and nitrogen dioxide (NO2) generated by internal combustion (IC) engines are implicated in adverse environmental and health effects. Even though lean-burn natural gas engines have traditionally emitted lower oxides of nitrogen (NOx) emissions compared to their diesel counterparts, natural gas engines are being further challenged to reduce NOx emissions to 0.1 g\\/bhp-hr. The Selective NOx Recirculation (SNR)
An evaluation of commercially available biological filters for recirculating aquaculture systems
Todd C. Guerdat; Thomas M. Losordo; John J. Classen; Jason A. Osborne; Dennis P. DeLong
Three different commercially available biological filters were evaluated in triplicate on a 60m3 tank-based Tilapia system under commercial warmwater growout conditions. The study was performed at the North Carolina State University Fish Barna commercial scale research and demonstration recirculating aquaculture facility operated by the department of Biological and Agricultural Engineering. Total ammoniacal nitrogen (TAN) removal rates were determined for the
Performance of a commercial recirculating alligator production system employing a paddle-washed floating bead filter
Aurelio A. DelosReyes; Kelly A. Rusch; Ronald F. Malone
A 2.83 m3 prototype paddle-washed bead filter for combined solids capture and biological filtration was successfully operated in a commercial recirculating alligator (Alligator mississippiensis) facility. The bead filter was originally designed and operated as a downflow filter but due to operational and water quality problems, it was reconfigured to operate in an upflow mode. Water quality conditions and filter performance
Media configuration and recirculation of upflow anaerobic floating filter for piggery wastewater treatment
Seunghwan Lee; Hongshin Lee; Seongeok Lee; Sukhuma Chitapornpan; Chart Chiemchaisri; Chongrak Polprasert; Kyuhong Ahn
An upflow anaerobic floating filter media (UAFF) reactor was applied to the treatment of synthetic and real piggery wastewater.\\u000a The effect of media configuration and internal recirculation on the system performance was studied. In the first experiment,\\u000a three-UAFF reactors filled with different media, i.e., polypropylene beads, sponge cubes and coconut fiber were continuously\\u000a fed with synthetic wastewater at upflow velocity
Combination of a bead filter and rotating biological contactor in a recirculating fish culture system
Aurelio A. delos Reyes; Thomas B. Lawson
The performance of the combination of a floating bead filter and an RBC employing 1-inch diameter N?orpacÛ tube media was evaluated in an intensive pilot scale recirculating system stocked with tilapia. The combination maintained favorable water quality, attaining practically complete TAN and NO2-N removal. The average overall removal across the FBF-RBC combination was 60ñ6 g TAN\\/day and 59ñ6 g NO2-N\\/day,
Nitrification performance of nitrifiers immobilized in PVA (polyvinyl alcohol) for a marine recirculating aquarium system
Jae-Koan Seo; Il-Hyong Jung; Mi-Ryung Kim; Byong Jin Kim; Soo-Wan Nam; Sung-Koo Kim
Characteristics of the nitrification processes with immobilized nitrifier consortium were evaluated for the development of the marine recirculating aquarium system. In order to evaluate the activity of the nitrifiers, a 45 l airlift reactor was used for the determination of ammonia removal rate for 40 days of operation. The ammonia removal efficiency rate was 98% with 23 g ammonia-N\\/m3\\/day, respectively.
Optoelectronic recirculating implementation of crossover interconnection network based on CMOS\\/SEED smart pixel technology
Fengguang Luo; Mingcui Cao; K. W Wong; L. M Cheng
A recirculating implementation of the crossover interconnection network based on optoelectronic architecture is presented in this paper. A flip-chip assembled CMOS\\/SEED (self-electro-optic-effect device) smart pixel array is used in this construction. The SEED array performs the optical-electrical conversion using a number of detectors and modulators while the CMOS devices handle the efficient logical processing. A combination of these two devices
Assessment of Corrosivity Associated with Exhaust Gas Recirculation in a Heavy-Duty Diesel Engine
Michael D. Kass; John F. Thomas; Dane Wilson; Samuel A. Lewis; Andy Sarles
A high-resolution corrosion probe was placed within the airhorn section of the exhaust gas recirculation (EGR) loop of a heavy-duty diesel engine. The corrosion rate of the mild-steel probe elements was evaluated as a function of fuel sulfur level, EGR fraction, dewpoint margin, and humidity. No significant corrosion was observed while running the engine using a No. 2 grade, <
High gradient magnetic beneficiation of dry pulverized coal via upwardly directed recirculating fluidization
Eissenberg, David M. (Oak Ridge, TN); Liu, Yin-An (Opelika, AL)
This invention relates to an improved device and method for the high gradient magnetic beneficiation of dry pulverized coal, for the purpose of removing sulfur and ash from the coal whereby the product is a dry environmentally acceptable, low-sulfur fuel. The process involves upwardly directed recirculating air fluidization of selectively sized powdered coal in a separator having sections of increasing diameters in the direction of air flow, with magnetic field and flow rates chosen for optimum separations depending upon particulate size.
Improvements to the k-epsilon model for calculations of turbulent recirculating flow
A. M. Gooray; C. B. Watkins; W. Aung
Improvements to the k-epsilon model of turbulence for numerical computation of recirculating flow beyond rearward-facing steps and pipe expansions are presented. The improvements involve sensitizing the models to the effects of streamline curvature and wall-damped pressure-strain interaction, through functionalizing C(mu). A procedure consisting of a sequence of two computational passes is performed to obtain optimal results over the entire flow
Recirculating accelerator driver for a high-power free-electron laser: a design overview
Courtlandt L. Bohn
Jefferson Lab is building a free-electron laser (FEL) to produce continuous-wave (cw), kW-level light at 3-6 ?m wavelength. A superconducting linac will drive the laser, generating a 5 mA average current, 42 MeV energy electron beam. A transport lattice will recirculate the beam back to the linac for deceleration and conversion of about 75% of its power into rf power.
Study of atmospheric stagnation, recirculation and ventilation potential at Narora Atomic Power Station NPP site.
Kumar, Deepak; Kumar, Avinash; Kumar, Vimal; Kumar, Jaivender; Ravi, P M
The atmosphere is an important pathway to be considered in assessment of the environmental impact of radioactivity releases from nuclear facilities. The estimation of concentration of released effluents in air and possible ground contamination needs an understanding of relevant atmospheric dispersion. This paper describes the meteorological characteristics of Narora Atomic Power Station (NAPS) Nuclear Power Project site by using the integral parameters developed by Allwine and Whiteman (Atmospheric Environment 28(4):713-721, 1994). Meteorological data measured during the period 2006-2010 were analysed. The integral quantities related to the occurrence of stagnation, recirculation and ventilation characteristics were studied for the NAPS site to assess the dilution potential of the atmosphere. Wind run and recirculation factors were calculated for a 24-h transport time using 5 years of hourly surface measurements of wind speed and direction. The occurrence of stagnation, recirculation and ventilation characteristics during 2006-2010 at the NAPS site is observed to be 33.8, 19.5 and 34.7 % of the time, respectively. The presence of strong winds with predominant wind direction NW and WNW during winter and summer seasons leads to higher ventilation (48.1 and 44.3 %) and recirculation (32.6 % of the summer season). The presence of more dispersed light winds during pre-winter season with predominant wind directions W and WNW results in more stagnation (59.7 % of the pre-winter season). Thus, this study will serve as an essential meteorological tool to understand the transport mechanism of atmospheric radioactive effluent release from any nuclear industry during the pre-operational as well as operational phase. PMID:22821255
Comparison of recirculation configurations for biological nutrient removal in a membrane bioreactor
Cagatayhan Bekir Ersu; Say Kee Ong; Ertan Arslankaya; Patrick Brown
A 12-L lab-scale membrane bioreactor (MBR), consisting of an anaerobic and anoxic compartment followed by an oxic plate-frame membrane compartment, was evaluated for carbonaceous and nutrient removals by varying the recirculation of mixed liquor and permeate. The hydraulic retention times (HRTs) for the anaerobic, anoxic, and oxic compartments were 2, 2, and 8h, respectively. The solids residence time (SRT) for
Analysis of the sodium recirculation theory of solute-coupled water transport in small intestine
Larsen, Erik Hviid; S½rensen, Jakob Balslev; S½rensen, Jens N½rkÌr
Our previous mathematical model of solute-coupled water transport through the intestinal epithelium is extended for dealing with electrolytes rather than electroneutral solutes. A 3Na+2K+ pump in the lateral membranes provides the energy-requiring step for driving transjunctional and translateral flows of water across the epithelium with recirculation of the diffusible ions maintained by a 1Na+-1K+2Cl? cotransporter in the plasma membrane facing the serosal compartment. With intracellular non-diffusible anions and compliant plasma membranes, the model describes the dependence on membrane permeabilities and pump constants of fluxes of water and electrolytes, volumes and ion concentrations of cell and lateral intercellular space (lis), and membrane potentials and conductances. Simulating physiological bioelectrical features together with cellular and paracellular fluxes of the sodium ion, computations predict that the concentration differences between lis and bathing solutions are small for all three ions. Nevertheless, the diffusion fluxes of the ions out of lis significantly exceed their mass transports. It is concluded that isotonic transport requires recirculation of all three ions. The computed sodium recirculation flux that is required for isotonic transport corresponds to that estimated in experiments on toad small intestine. This result is shown to be robust and independent of whether the apical entrance mechanism for the sodium ion is a channel, a SGLT1 transporter driving inward uphill water flux, or an electroneutral Na+K+2Cl? cotransporter. PMID:12096047
Advanced Horizontal Well Recirculation Systems for Geothermal Energy Recovery in Sedimentary and Crystalline Formations
Bruno, Mike; Detwiler, Russell L; Lao, Kang; Serajian, Vahid; Elkhoury, Jean; Diessl, Julia; White, Nicky
There is increased recognition that geothermal energy resources are more widespread than previously thought, with potential for providing a significant amount of sustainable clean energy worldwide. Recent advances in drilling, completion, and production technology from the oil and gas industry can now be applied to unlock vast new geothermal resources, with some estimates for potential electricity generation from geothermal energy now on the order of 2 million megawatts. The primary objectives of this DOE research effort are to develop and document optimum design configurations and operating practices to produce geothermal power from hot permeable sedimentary and crystalline formations using advanced horizontal well recirculation systems. During Phase I of this research project Terralog Technologies USA and The University of California, Irvine (UCI), have completed preliminary investigations and documentation of advanced design concepts for paired horizontal well recirculation systems, optimally configured for geothermal energy recovery in permeable sedimentary and crystalline formations of varying structure and material properties. We have also identified significant geologic resources appropriate for application of such technology. The main challenge for such recirculation systems is to optimize both the design configuration and the operating practices for cost-effective geothermal energy recovery. These will be strongly influenced by sedimentary formation properties, including thickness and dip, temperature, thermal conductivity, heat capacity, permeability, and porosity; and by working fluid properties.
Seismic imaging of the mantle transition zone
Cao, Qin, Ph. D. Massachusetts Institute of Technology
In this thesis, we developed a generalized Radon transform of SS precursors for large-scale, high-resolution seismo-stratigraphy of the upper mantle transition zone. The generalized Radon transform (GRT) is based on the ...
Estimation of Hydraulic Properties Influencing Recharge and Contaminant Transport through Complex Vadose Zones by Analyzing Perched Water Data from the 1994 Large-Scale Infiltration Test at the Idaho National Laboratory
NASA Astrophysics Data System (ADS)
Creasey, K. M.; Nimmo, J. R.
Layers of strong geologic contrast within the vadose zone can control recharge and contaminant transport to underlying aquifers. Above the eastern Snake River Plain Aquifer, multiple sedimentary interbeds are interspersed between fractured basalt. These interbeds have a variety of thicknesses and hydraulic properties, and can impede water flow, which allows perched water to collect on the interbeds. The Large-Scale Infiltration Test (LSIT) of 1994 at the Idaho National Laboratory (INL) maintained a circular pond, 200 meters in diameter, at a constant head for 20 days. Monitoring wells were arranged in circles of different radii around and within the pond, and perched water levels on a major sedimentary interbed, 55 meters below ground surface, were measured over time. Data showed that water formed a mound on the interbed before seeping through the interbed. Such behavior is consistent with a hypothesis of rapid flow through the fractured basalt being impeded by the sedimentary interbed. In 2014, the USGS, in cooperation with the U.S. Department of Energy, used a modified version of a Hantush (1967) equation to model the time-dependent perched water table heights from the LSIT as a function of radial distance from the pond center. The modeled volume change between time-steps and the known inflows to the pond were used in a mass balance to estimate the time-varying volume of water seeping through the interbed. This volume of water, the height of perched water, and the interbed thickness were used in Darcy's Law to estimate the effective saturated hydraulic conductivity of the impeding interbed. Results indicate a slightly higher effective conductivity than laboratory measurements of small core samples taken from the interbed, reflecting the presence of fractures or other heterogeneities that facilitate field-scale flow through the interbed. Applied to other locations, this method can improve estimates of recharge and contaminant transport to underlying aquifers.
Diffuse large B-cell lymphoma of the uterus suspected of having transformed from a marginal zone B-cell lymphoma harboring trisomy 18: a case report and review of the literature
Sugimoto, Kei-Ji; Imai, Hidenori; Shimada, Asami; Wakabayashi, Mutsumi; Sekiguchi, Yasunobu; Nakamura, Noriko; Sawada, Tomohiro; Izumi, Hiroshi; Ota, Yasunori; Komatsu, Norio; Noguchi, Masaaki
The patient was a 72-year-old female with the chief complaint of abdominal fullness. A giant primary myoma of the uterine cervix was suspected, and total hysterectomy was performed. Based on a postoperative histopathological examination of the tumor a diagnosis of diffuse large B-cell lymphoma (DLBCL) was made in the uterus and a mass in the greater omentum was diagnosed as a marginal zone B-cell lymphoma (MZBCL). No flow-cytometry studies or chromosome or gene examinations were performed on a fresh specimen. The results of an examination of a paraffin block histopathology specimen by fluorescence in-situ hybridization (FISH) showed no mucosa associated lymphoid tissue lymphoma translocation gene 1 (MALT1) (18q21.1), B-cell lymphoma 2 (BCL2) (18q21.3), or BCL6 (3q27) split signals in either the uterus or the greater omentum, however, trisomy 18 was detected in approximately 50%-70% of the tumor cells in both the uterus and the greater omentum. Trisomy 18 was present in around 15-33% of the DLBCL cells and MZBCL cells. These findings suggested a strong possibility that the tumor cells in the uterus and greater omentum were the same clone and that transformation from MZBCL to DLBCL had occurred. Since DLBCLs that result from a transformation usually have a worse outcome than de novo DLBCLs, even when a DLBCL seems to have originated in the uterus the surrounding tissue should always be examined, and caution should be exercised in regard to transformation from a low-grade B-cell lymphoma to a DLBCL. PMID:24294388
Unsaturated-Zone Dynamics in a Volcanogenic CO2 Emission Zone
D. A. Stonestrom; C. D. Farrar
Since 1998, large quantities of carbon dioxide (CO2) have been venting through the unsaturated zone on Mammoth Mountain, the western high point of the rim bounding Long Valley Caldera (Inyo County, California). CO2 fluxes are characterized by high temporal variability, the causes of which are not fully understood. Flow in the unsaturated zone entails downward percolating snowmelt (liquid) that encounters
The potential use of constructed wetlands in a recirculating aquaculture system for shrimp culture.
Lin, Ying-Feng; Jing, Shuh-Ren; Lee, Der-Yuan
A pilot-scale constructed wetland unit, consisting of free water surface (FWS) and subsurface flow (SF) constructed wetlands arranged in series, was integrated into an outdoor recirculating aquaculture system (RAS) for culturing Pacific white shrimp (Litopenaeus vannamei). This study evaluated the performance of the wetland unit in treating the recirculating wastewater and examined the effect of improvement in water quality of the culture tank on the growth and survival of shrimp postlarvae. During an 80-day culture period, the wetland unit operated at a mean hydraulic loading rate of 0.3 m/day and effectively reduced the influent concentrations of 5-day biochemical oxygen demand (BOD5, 24%), suspended solids (SS, 71%), chlorophyll a (chl-a, 88%), total ammonium (TAN, 57%), nitrite nitrogen (NO2-N, 90%) and nitrate nitrogen (NO3-N, 68%). Phosphate (PO4-P) reduction was the least efficient (5.4%). The concentrations of SS, Chl-a, turbidity and NO3-N in the culture tank water in RAS were significantly (P
Partitioning sources of recharge in environments with groundwater recirculation using carbon-14 and CFC-12
NASA Astrophysics Data System (ADS)
Bourke, Sarah A.; Cook, Peter G.; Dogramaci, Shawan; Kipfer, Rolf
Groundwater recirculation occurs when groundwater is pumped from an aquifer onto the land surface, and a portion of that water subsequently infiltrates back to the aquifer. In environments where groundwater is recirculated, differentiation between various sources of recharge (e.g. natural rainfall recharge vs. recirculated water) can be difficult. Groundwater age indicators, in particular transient trace gases, are likely to be more sensitive tracers of recharge than stable isotopes or chloride in this setting. This is because, unlike stable isotopes or chloride, they undergo a process of equilibration with the atmosphere, and historical atmospheric concentrations are known. In this paper, groundwater age indicators (14C and CFC-12) were used as tracers of recharge by surplus mine water that is discharged to streams. Ternary mixing ratios were calculated based on 14C and CFC-12 concentrations measured along three transects of piezometers and monitoring wells perpendicular to the creeks, and from dewatering wells. Uncertainty in calculated mixing ratios was estimated using a Monte Carlo approach. Ternary mixing ratios in dewatering wells suggest that recharge by mine water accounted for between 10% and 87% of water currently abstracted by dewatering wells. The calculated mixing ratios suggest that recharge by mine water extends to a distance of more than 550 m from the creeks. These results are supported by seepage flux estimates based on the water and chloride balance along the creeks, which suggest that 85-90% of mine water discharged to the creeks recharges the aquifer and recharge by mine water extends between 110 and 730 m from the creeks. Mixing calculations based on gaseous groundwater age indicators could also be used to partition recharge associated with agricultural irrigation or artificial wetland supplementation.
Fresnel zone interferometric imaging
D. J. Brady; D. L. Marks; R. Stack
We describe how Fourier analysis in projective coordinates allows inversion in the Fresnel zone. Since the longitudinal resolution of 3D coherence imaging falls inversely in the square of range in both the Fresnel and Fraunhofer zones, extension to the Fresnel zone dramatically improves longitudinal resolution by removing far-field range constraints in Michelson rotational shear interferometry
NSDL National Science Digital Library
This is an activity featuring a time zone map useful when teaching an interdisciplinary social studies and math unit focusing on geography and the time zones. It underscores the role of the earth's rotation in everyday life, and the need to understand the relationships between earth rotation, day and night, and time zones around the world.
NASA Technical Reports Server (NTRS)
Griner, D. B.
System developed for studying use of laser beam for zone-refining semiconductors and metals. Specimen scanned with focused CO2 laser beam in such way that thin zone of molten material moves along specimen sweeps impurities with it. Zone-melting system comprises microcomputer, laser, electromechanical and optical components for beam control, vacuum chamber that holds specimen, and sensor for determining specimen temperature.
The effect of manganese fuel additive and exhaust gas recirculation on diesel particulate emissions
Hilden, D.L.; Bergin, S.P.
A study was undertaken to determine the combined effect of methylcyclopentadienyl manganese tricarbonyl (MMT) fuel additive and exhaust gas recirculation (EGR) on particulate and oxides of nitrogen (NOx) emissions from a single-cylinder light-duty diesel engine. Further, the physical and chemical properties of the particulate material were determined to better understand MMT and EGR effects on these emissions. The results showed that EGR always decreased NOx emissions, and that MMT had no significant effect on them. In addition, EGR always increased particulate emissions, but MMT was effective in limiting this increase especially at high EGR levels.
Experimental Study of the Circulation Air Volume of Recirculation Evaporative Cooling
Xiong, J.; Liu, Z.; Wang, C.; Chen, G.
ICEBO2006, Shenzhen, China HVAC Technologies for Energy Efficiency, Vol. IV-11-3 Experimental Study of the Circulation Air Volume of Recirculation Evaporative Cooling 1 Jun Xiong ZeHua Liu Chao Wang GuoJie Chen Bachelor Senior.... Pre-design and design tools for evapora- tive cooling[J]. ASHRAE Transaction: Symposia. 2001.Vol. 107 part1: 501-510. [5] LiangShi Ding, JianJun Wang, MingJian Jiang. Investigations of the thermal performance of in- direct evaporative plate heat...
Measurement and control of exhaust gas recirculation with an oxygen pumping device
Logothetis, E.; Soltis, R.E.
This patent describes an electrochemical device for measuring the percentage of exhaust gas recirculation (EGR) in an intake air and exhaust gas mixture of an internal combustion engine. The device includes a first solid electrochemical pump cell; a second solid electrochemical pump cell; a supporting structure coupled to the first and second pump cells; an aperture for providing communication between the restricted volume; a first external circuit means; a second external circuit means; a third external circuit means; and means defining a diffusion barrier between the first pump cell and the second pump cell.
Model experiment to search for emittance gain of recirculating heavy ion beam
Lauer, E.J.; Barnard, J.J.; Hewett, D.W.; Kulke, B.; Yu, S.S.
An experiment is underway to measure the increase in emittance of a 13.2 KeV, 50{mu}A, Kr{sup 84} beam and a 8.5 KeV, 20{mu}A, Xe{sup 131} beam in passing through the ATA 30{degree} bend beam director.'' The ratio of the non-linear term divided by the linear term in Kelvin Neil's equation of motion is calculated for the full scale rings of the proposed recirculator and for the model experiment. 1 tab.
Main zones of the intertidal zone
NSDL National Science Digital Library
Katie Hale (California State University, Fullerton; Student, Biological Sciences)
The intertidal zone is found where the tides rise and fall daily, alternatively submerging and exposing the shore to ocean water. Organisms must be able to tolerate times of intense sunlight, little moisture, and wave forces.
Main zones of the intertidal zone
NSDL National Science Digital Library
Katie Hale (CSUF; Biological Sciences)
The intertidal zone is found where the tides rise and fall daily, alternatively submerging and exposing the shore to ocean water. Organisms must be able to tolerate times of intense sunlight, little moisture, and wave forces.
Large-eddy simulation of street canyons and urban microclimate using Uintah:MPMICE
NASA Astrophysics Data System (ADS)
Nemati Hayati, A.; Stoll, R., II; Harman, T.; Pardyjak, E.
Urban microclimate plays an important role in urban water use, energy use, pollutant transport, and the general comfort and well-being of urban inhabitants. The microclimate interacts locally with urban morphology, water levels, properties of urban surfaces, and vegetation cover all of which contribute significantly to the strong spatial variability observed in urban areas. Considerable parts of urban open spaces take the form of street canyons. These urban street canyons play a remarkable role in creating urban microclimates. Within street canyons themselves, a wide variety of phenomena contribute to complex flow patterns. These include various flow structures such as wake fields, circulation zones, isolated roughness flow, wake interference and skimming flows. In addition, heat fluxes from the buildings and the surrounding area enhance the complexity of the flow field inside the canyon. Here, we introduce Uintah:MPMICE for the simulation of fluid structure interactions in urban flows. Uintah:MPMICE has been developed in a massively parallel computational infrastructure, uses material points to represent buildings, and the large-eddy simulation (LES) technique to represent momentum and scalar transport. To validate Uintah:MPMICE, simulations of typical street canyons are compared against published wind tunnel particle imaging velocimetry (PIV) data for the cases of step-up and step-down street canyons. Our findings show promising results in capturing major flow features, namely wake fields, recirculation zones, wake interference, vortex structures, and flow separation in street canyons. LES results demonstrate the ability of the simulations to predict flow topology details such as secondary circulation zones and wall-originating elevated shear layers in step-up and step-down cases, respectively. Furthermore, mean flow and variance statistics indicate sensitivity to inlet boundary conditions; upstream turbulence generation method, in particular, has a significant impact on the LES results.
Nitrogen removal in a two-stage, re-circulating waste stabilisation pond system.
Baskaran, K; Farago, L
Waste stabilisation ponds are used widely in Australia and other parts of the world for treating wastewater from domestic and a wide range of industrial sources. It remains a popular form of treatment for wastewater for many small rural towns. The development of a two-stage, re-circulating waste stabilisation pond incorporating algal-bacterial biofilm represents a new approach to increasing the functioning biomass within the water column to improve treatment efficiency. This new approach will be a more viable and economical option for most of the existing waste stabilisation ponds to achieve significant nitrogen removal than converting them to another form of biological nutrient removal processes. A laboratory-scale, two-stage, re-circulating system incorporating "Bio-Tube" plastic modules as attached growth medium has been tested using synthetic wastewater. It has been proven that nitrification-denitrification was the primary mechanism for nitrogen removal in such a system operated under complete mix conditions. During the experimental period, average removal efficiencies of 90-95% of ammonia nitrogen and 65-85% of total nitrogen removal were achieved with influent COD of 600 mg/L and total nitrogen of 70 mg/L. PMID:17591196
Investigation of sludge re-circulating clarifiers design and optimization through numerical simulation.
Davari, S; Lichayee, M J
In steam thermal power plants (TPP) with open re-circulating wet cooling towers, elimination of water hardness and suspended solids (SS) is performed in clarifiers. Most of these clarifiers are of high efficiency sludge re-circulating type (SRC) with capacity between 500-1,500 m3/hr. Improper design and/or mal-operation of clarifiers in TPPs results in working conditions below design capacity or production of soft water with improper quality (hardness and S.S.). This causes accumulation of deposits in heat exchangers, condenser tubes, cooling and service water pipes and boiler tubes as well as increasing the ionic load of water at the demineralizing system inlet. It also increases the amount of chemical consumptions and produces more liquid and solid waste. In this regard, a software program for optimal design and simulation of SRCs has been developed. Then design parameters of existing SRCs in four TPPs in Iran were used as inputs to developed software program and resulting technical specifications were compared with existing ones. In some cases improper design was the main cause of poor outlet water quality. In order to achieve proper efficiency, further investigations were made to obtain control parameters as well as design parameters for both mal-designed and/or mal-operated SRCs. PMID:14753549
Flue gas recirculation and enhanced performance of waste incinerators under waste uncertainty.
Tsiliyannis, Christos Aristeides
Variations in waste quantities and composition affect incinerator operating conditions and performance. Fluegas volumes consititute a dominant environmental and financial consideration for efficient waste incinerator (WI) operation, since they affect the temperature, throughput, air pollution control system (APCS) residence time, and pollutant emissions, when the charging rate or composition of any waste is varying. Fluegas recirculation (FGR) in WI is an effective technique for reducing WI atmospheric pollution, mainly NOx emissions, albeit affecting WI throughput, temperature and destruction/removal efficiency. FGR refers to mass recirculation of a possibly cooled fraction of fluegases and differs substantially from fluegas heat recovery. The present work shows that, besides emission control, suitable manipulation of FGR enhances WI performance under waste uncertainty, enabling higher throughput, at the desired temperature and within the allowed APCS residence time range. A dimensionless parameter related to the uncertain wastes' net enthalpy contribution is isolated, which encompasses heat of reaction and enthalpy outflows from fluegas and solids and which reveals whether throughput is decreasing or increasing with temperature and FGR ratio. Normalized throughput and total fluegas volume isotherms manifest the interdependence and enable manipulation for enhanced environmental and economic performance. PMID:23781842
Linear Fixed-Field Multi-Pass Arcs for Recirculating Linear Accelerators
V.S. Morozov, S.A. Bogacz, Y.R. Roblin, K.B. Beard
Recirculating Linear Accelerators (RLA's) provide a compact and efficient way of accelerating particle beams to medium and high energies by reusing the same linac for multiple passes. In the conventional scheme, after each pass, the different energy beams coming out of the linac are separated and directed into appropriate arcs for recirculation, with each pass requiring a separate fixed-energy arc. In this paper we present a concept of an RLA return arc based on linear combined-function magnets, in which two and potentially more consecutive passes with very different energies are transported through the same string of magnets. By adjusting the dipole and quadrupole components of the constituting linear combined-function magnets, the arc is designed to be achromatic and to have zero initial and final reference orbit offsets for all transported beam energies. We demonstrate the concept by developing a design for a droplet-shaped return arc for a dog-bone RLA capable of transporting two beam passes with momenta different by a factor of two. We present the results of tracking simulations of the two passes and lay out the path to end-to-end design and simulation of a complete dog-bone RLA.
Progress toward a prototype recirculating induction accelerator for heavy-ion fusion
Friedman, A.; Barnard, J.J.; Cable, M.D. [Lawrence Livermore National Lab., CA (United States)] [and others
The US Inertial Fusion Energy (IFE) Program is developing induction accelerator technology toward the goal of electric power production using Heavy-Ion beam-driven inertial Fusion (HIF). The recirculating induction accelerator promises driver cost reduction by repeatedly passing the beam through the same set of accelerating and focusing elements. The authors present plans for and progress, toward a small (4.5-m diameter) prototype recirculator which will accelerate K{sup +} ions through 15 laps, from 80 to 320 keV and from 2 to 8 mA. Beam confinement is effected via permanent-magnet quadrupoles; bending is via electric dipoles. Scaling laws, and extensive particle and fluid simulations of the space-charge dominated beam behavior, have been used to arrive at the design. An injector and matching section are operational. Initial experiments are investigating intense-beam transport in a linear magnetic channel; near-term plans include studies of transport around a bend. Later experiments will study, insertion/extraction and acceleration with centroid control.
LUX - A Recirculating Linac-based Ultrafast X-ray Source
Corlett, J.N.; Barletta, W.A.; DeSantis, S.; Doolittle, L.; Fawley, W.M.; Green, M.A.; Heimann, P.; Leone, S.R.; Lidia, S.; Li, D.; Ratti, A.; Robinson, K.; Schoenlein, R.; Staples, J.; Wan, W.; Wells, R.; Wilcox, R.; Wolski, A.; Zholents, A. [Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Parmigiani, F. [Laboratorio TASC-INFM (Italy)
We describe the design of a proposed source of ultra-fast synchrotron radiation x-ray pulses based on a recirculating superconducting linac, with an integrated array of ultrafast laser systems. The source produces x-ray pulses with duration of 10-50 fs at a 10 kHz repetition rate, with tunability from EUV to hard x-ray regimes, and optimized for the study of ultra-fast dynamics. A high-brightness rf photocathode provides electron bunches. An injector linac accelerates the beam to the 100 MeV range, and is followed by four passes through a 700 MeV recirculating linac. Ultrafast hard x-ray pulses are obtained by a combination of electron bunch manipulation, transverse temporal correlation of the electrons, and x-ray pulse compression. EUV and soft x-ray pulses as short as 10 fs are generated in a harmonic-cascade free electron laser scheme. We describe the facility major systems and performance.
Fluid processes in subduction zones.
Peacock, S A
Fluids play a critical role in subduction zones and arc magmatism. At shallow levels in subduction zones (<40 kilometers depth), expulsion of large volumes of pore waters and CH(4)-H(2)O fluids produced by diagenetic and low-grade metamorphic reactions affect the thermal and rheological evolution of the accretionary prism and provide nutrients for deep-sea biological communities. At greater depths, H(2)O and CO(2) released by metamorphic reactions in the subducting oceanic crust may alter the bulk composition in the overlying mantle wedge and trigger partial melting reactions. The location and conse-quences of fluid production in subduction zones can be constrained by consideration of phase diagrams for relevant bulk compositions in conjunction with fluid and rock pressure-temperature-time paths predicted by numerical heat-transfer models. Partial melting of subducting, amphibole-bearing oceanic crust is predicted only within several tens of million years of the initiation of subduction in young oceanic lithosphere. In cooler subduction zones, partial melting appears to occur primarily in the overlying mantle wedge as a result of fluid infiltration. PMID:17784486
A numerical study of the heat transfer through a fluid layer with recirculating flow between concentric and eccentric spheres
NASA Astrophysics Data System (ADS)
Rasmussen, R. M.; Levizzani, V.; Pruppacher, H. R.
A numerical study has been made of the heat transfer through a fluid layer with recirculating flow. The outer fluid surface was assumed to be spherical, while the inner surface consisted of a sphere concentrically or eccentrically located with respect to the outer spherical surface. The recirculating flow was assumed to be driven by a gas flow creating stress on the fluid's outer surface so that creeping (low Reynolds number) flow developed in its interior. The present study solves the Stokes equation of motion and the convective diffusion equation in bispherical coordinates and presents the streamline and isotherm patterns.
The use of an open channel, low pressure UV reactor for water treatment in low head recirculating aquaculture systems (LH-RAS)
Hadas Mamane; Angelo Colorni; Ido Bar; Ido Ori; Noam Mozes
This study examined the effectiveness of an open channel, low pressure (LP), ultraviolet (UV) reactor for water treatment in a low head (LH) recirculating aquaculture system (RAS). Currently available UV reactors use high pressure pumps and submerged bulbs. The reactor in this study makes use of the head gained by the water recirculation of the LH-RAS without the need for
The performance and impact of a bubble-wash bead filter in a recirculating green water larval culture system for delta smelt ( Hypomesus transpacificus)
Tien-Chieh Hung; Raul H. Piedrahita
Delta smelt are cultured at the UC Davis Fish Conservation and Culture Lab (FCCL) for research purposes. The culture systems used are based on recirculation technology to ensure optimum water quality for the fish at each life stage. Larval culture takes place in recirculation systems with green water to which a Nannochloropsis algal concentrate is added to maintain a turbidity
Morphological diversity and complex sediment recirculation on the ebb delta of a macrotidal inlet (Normandy, France): A multiple LiDAR dataset approach
NASA Astrophysics Data System (ADS)
Montreuil, Anne-Lise; Levoy, Franck; Bretel, Patrice; Anthony, Edward J.
The shoreline in the vicinity of inlets can exhibit considerable variability in morphology in both space and time. Most studies on inlets and their adjacent shores have focused on the morphodynamics of sediment by-passing mechanisms generated by longshore transport. For the first time, the morphology, sedimentary features, sediment budgets and patterns of evolution of the shoreline and ebb delta in a macrotidal inlet system have been investigated using seven LiDAR topographic surveys in Normandy, France, over a period of 3.7 years from February 2009 to October 2012. The ebb delta shows strong development on the northern flank of the inlet, expressed by a large sand spit and two types of superimposed dynamic sandy features: eight long-crested and highly mobile transverse bars and a large swash bar. Sand transport from N-S on the updrift beach feeds the growth of the distal part of the spit. This sand supply is further augmented by the onshore movement of a large swash bar welding to the upper foreshore. However, the main topographic changes were induced by the northward migration of the transverse bars on the ebb platform. This is driven by strong northward-directed tidal currents parallel to the shore. The bars exhibit a more complex morphology and dynamics along the seaward margin of the ebb delta where their mobility is controlled by wave action. Topographic measurements suggest a clear sand recirculation pattern. In this morphodynamic model, sand coming from the updrift upper beach is transported southward and deposited at the distal end of the spit, where it serves to construct transverse bars close to the tidal inlet. Transverse bar migration ends in the wave-exposed northern margin of the ebb delta, where they are integrated into the shallow dissipative shoreface sand sink. This sink nourishes the southward longshore transport to feed growth of the large swash bar and southward spit elongation. This semi-circular recirculation cell model involves an inversion of sand movement close to the inlet and emphasizes the combined role of tidal currents and waves in the large-scale 3D ebb-delta sediment dynamics in this macrotidal setting, in contrast to the much more commonly reported alongshore sediment by-passing mode of microtidal inlets.
NSDL National Science Digital Library
COSEE West
In this activity, learners will create a diagram of the ocean zones and determine what organisms live in each zone. Learners will draw the appropriate scale to demark meters (and conversion to feet) from 0-6000m and draw the zones that correspond to the geological structures of the ocean basin. Finally, learners will use their critical thinking skills to determine where in the ocean each organism lives and place the organism in the habitat that is within the limitations for survival.
80 FR 34170 - Notice of Intent To Prepare a Recirculated Draft Environmental Impact Report/Supplemental Draft...
Federal Register 2010, 2011, 2012, 2013, 2014
The Bureau of Reclamation and the California Department of Water Resources intend to prepare a partially Recirculated Draft Environmental Impact Report/Supplemental Draft Environmental Impact Statement (RDEIR/SDEIS) on the Draft Bay Delta Conservation Plan and Natural Community Conservation Plan (BDCP, or the Plan). The RDEIR/SDEIS will describe and analyze refinement of the resource area......
Design and Evaluation of a Water Recirculation Loop Maintenance Device for the Advanced Spacesuit Water Membrane Evaporator
NASA Technical Reports Server (NTRS)
Steele, John W.; Rector, Tony; Bue, Grant C.; Campbell, Colin; Makinen, Janice
A dual-bed device to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop has been designed and is undergoing testing. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing Sublimator technology. The driver for the development of a water recirculation maintenance device is to further enhance this advantage through the leveraging of fluid loop management lessons-learned from the International Space Station (ISS). A bed design that was developed for a Hamilton Sundstrand military application, and considered for a potential ISS application with the Urine Processor Assembly, provides a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The bed design further leverages a sorbent developed for ISS that introduces a biocide in a microgravity-compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a clear demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware.
Performance of a Water Recirculation Loop Maintenance Device and Process for the Advanced Spacesuit Water Membrane Evaporator
NASA Technical Reports Server (NTRS)
Rector, Tony; Steele, John W.; Bue, Grant C.; Campbell, Colin; Makinen, Janice
A water loop maintenance device and process to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop has been undergoing a performance evaluation. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing Sublimator technology. The driver for the water recirculation maintenance device and process is to further enhance this advantage through the leveraging of fluid loop management lessons-learned from the International Space Station (ISS). A bed design that was developed for a Hamilton Sundstrand military application, and considered for a potential ISS application with the Urine Processor Assembly, provides a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The maintenance process further leverages a sorbent developed for ISS that introduces a biocide in a microgravity-compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware. This
The effects of carbon dioxide on performance and histopathology of rainbow trout Oncorhynchus mykiss in water recirculation aquaculture systems
Christopher Good; John Davidson; Carla Welsh; Kevin Snekvik; Steven Summerfelt
Chronic exposure to elevated levels of dissolved carbon dioxide (CO2) has been linked to reduced growth, physiological disturbances and negative health outcomes in intensively reared fish. Although pumping to a degassing tower can lower concentrations of dissolved CO2 in water recirculation aquaculture systems (WRAS), pumping can be a significant cost for operators. A 6-month trial was conducted to compare the
An integrated recirculating aquaculture system (RAS) for land-based fish farming: The effects on water quality and fish production
Shi-Yang Zhang; Gu Li; Hui-Bi Wu; Xing-Guo Liu; Yan-Hong Yao; Ling Tao; Huang Liu
To mitigate the serious water pollution caused by the rapid expansion of the aquaculture industry in recent years, the development of improved aquaculture systems with more efficient water usage and less environmental impact has become essential. In this study, a land-based recirculating aquaculture system (RAS) was established that consisted of purification units (i.e., a primary biological pond, two parallel horizontal
A novel approach to denitrification processes in a zero-discharge recirculating system for small-scale urban aquaculture
Alon Singer; Shmuel Parnes; Amit Gross; Amir Sagi; Asher Brenner
This paper presents an innovative process to solve the nitrate build-up problem in recirculating aquaculture systems (RAS). The novel aspects of the process lie in a denitrification bioreactor system that uses solid cotton wool as the primary carbon source and a unique degassing chamber. In the latter, the water is physically stripped of dissolved gaseous O2 (by means of a
Microparticles in recirculating aquaculture systems: particle size analysis of culture water from a commercial Atlantic salmon site
R. N. Patterson; K. C. Watts
As part of a larger study of micro-particles in a recirculating, cold water aquaculture system for juvenile Atlantic salmon (Salmo salar), particle size analyses were carried out on the culture and makeup waters over several months followed by samples of feed stirred in water. The particle size distributions followed the power law described in [Aquacult. Eng. 19 (1999): 259] but
Characterization of the microbial community and nitrogen transformation processes associated with moving bed bioreactors in a closed recirculated mariculture system
Yossi Tal; Joy E. M. Watts; Susan B. Schreier; Kevin R. Sowers; Harold J. Schreier
The microbial consortium of a moving bed bioreactor (MBB) connected to a marine recirculating aquaculture system was examined by denaturing gradient gel electrophoresis (DGGE) of amplified 16S rRNA gene fragments. Both ammonia and nitrite oxidizers, Nitrosomonas cryotolerans and Nitrospira marina, respectively, were found associated with the marine system as well as a number of heterotrophic bacteria, including Pseudomonas sp. and
Water quality and rainbow trout performance in a Danish Model Farm recirculating system: Comparison with a flow through system
Emmanuelle Roque dorbcastel; Jean-Paul Blancheton; Alain Belaud
The objective was to compare water quality and fish growth and mortality in a pilot scale recirculating system (RS) and a control tank in flow through system (FTS). The RS was designed after the Danish Model Trout Farm and operated with a make up water renewal rate of 9m3kg-1 of fish produced. RS water quality did not decrease significantly with
The use of high rate algal ponds for the treatment of marine effluent from a recirculating fish rearing system
P Pagand; J-P Blancheton; J Lemoalle; C Casellas
A high rate algal pond (HRAP) system was used to treat effluent from a recirculating sea water aquaculture system in southern France. Dicentrarchus labrax L. were farmed at a high density, with effluents containing an average of 10 mg L1 dissolved inorganic nitrogen (DIN) and 1.3 mg L1 reactive phosphorus (RP). On a yearly basis, the algal pond removed 59%
Effect of thermal buoyancy on the recirculating flow in a solar pond for energy extraction and heat rejection
C. K. Cha; Y. Jaluria
An analytical and numerical study is carried out to determine the effect of buoyancy, resulting from temperature differences, on the recirculating flow arising in enclosed regions, such as the surface and storage layers of a salt-gradient solar pond, due to the discharge of fluid into it. The study investigates the timedependent flow, considering an initially isothermal or thermally stratified fluid
Characteristic time series and operation region of the system of two tank reactors (CSTR) with variable division of recirculation stream
Henryk Merta
The paper deals with a system of a cascade of two tank reactors, being characterized by the variable stream of recirculating fluid at each stage. The assumed mathematical model enables one to determine the systems dynamics for the case when there is no time delay and for the opposite case. The time series of the conversion degree and of the
New chemical removing and air cooling technology for clean room recirculation air using chilled pure water showering method
H. Wakamatsu; M. Matsuki; N. Tanaka; Y. Iwanaga; K. Murata
We have developed a new chemical removing and air cooling technique for clean room recirculation air using a gas-liquid contact method that consists of a combination of chilled pure water showering and optimum packing material. We have tested a new treatment system using this technique in an actual photolithography clean room finding many kinds of chemical contaminants of water-solubility substances
Physiologic and metabolic influences on enterohepatic recirculation: Simulations based upon the disposition of valproic acid in the rat
Gary M. Pollack; Kim L. R. Brouwer
The potential influence of alterations in several physiologic processes (hepatocellular egress, biliary excretion, gastrointestinal transit) and biotransformation steps (oxidative metabolism, glucuronidation) on the disposition of agents subject to significant enterohepatic recirculation (ER) via the glucuronide conjugate was examined in a series of simulation experiments. The model of ER developed was based upon the disposition of valproic acid (VPA) and valproate
Effect of exhaust gas recirculation on emissions from a flame-tube combustor using Liquid Jet A fuel
NASA Technical Reports Server (NTRS)
Marek, C. J.; Tacina, R. R.
The effects of uncooled exhaust gas recirculation as an inert diluent on emissions of oxides of nitrogen (NO + NO2) and on combustion efficiency were investigated. Ratios of recirculated combustion products to inlet airflow were varied from 10 to 80 percent by using an inlet air ejector nozzle. Liquid Jet A fuel was used. The flame-tube combustor was 10.2 cm in diameter. It was operated with and without a flameholder present. The combustor pressure was maintained constant at 0.5 MPa. The equivalence ratio was varied from 0.3 to 1.0. The inlet air temperature was varied from 590 to 800 K, and the reference velocity from 10 to 30 m/sec. Increasing the percent recirculation from 10 to 25 had the following effects: (1) the peak NOx emission was decreased by 37 percent, from 8 to 5 g NO2/kg fuel, at an inlet air temperature of 590 K and a reference velocity of 15 m/sec; (2) the combustion efficiency was increased, particularly at the higher equivalence ratios; and (3) for a high combustion efficiency of greater than 99.5 percent, the range of operation of the combustor was nearly doubled in terms of equivalence ratio. Increasing the recirculation from 25 to 50 percent did not change the emissions significantly.
Production characteristics and body composition of juvenile cobia fed three different commercial diets in recirculating aquaculture systems
Technology Transfer Automated Retrieval System (TEKTRAN)
The effect of feeding three commercial diets on production characteristics and body composition of juvenile cobia Rachycentron canadum reared using recirculating aquaculture systems (RAS) was evaluated in a 56 d growth trial. Juvenile cobia (29.2 +/= 0.7 g, mean weight +/= SE) were stocked into thr...
Study of low emission homogeneous charge compression ignition (HCCI) engine using combined internal and external exhaust gas recirculation (EGR)
Lei Shi; Yi Cui; Kangyao Deng; Haiyong Peng; Yuanyuan Chen
This paper focuses on the effects of internal and cooled external exhaust gas recirculation (EGR) on the combustion and emission performance of diesel fuel homogeneous charge compression ignition (HCCI). The use of fuel injection before the top center (TC) of an exhaust stroke and the negative valve overlap (NVO) to form the homogeneous mixture achieves low NOx and smoke emissions
NO x emission and performance data for a hydrogen fueled internal combustion engine at 1500 rpm using exhaust gas recirculation
James W Heffel
This paper describes six experiments conducted on a 2-liter, 4-cylinder Ford ZETEC internal combustion engine developed to operate on hydrogen fuel. The experiments were conducted to ascertain the effect exhaust gas recirculation (EGR) and a standard 3-way catalytic converter had on NOx emissions and engine performance. All the experiments were conducted at a constant engine speed of 1500rpm and each
NO x emission reduction in a hydrogen fueled internal combustion engine at 3000 rpm using exhaust gas recirculation
James W Heffel
This paper describes five experiments conducted on a 2-l, 4-cylinder Ford ZETEC internal combustion engine (ICE) developed to operate on hydrogen fuel. The experiments were conducted to ascertain the effect exhaust gas recirculation (EGR) and a standard 3-way catalytic converter had on NOx emissions and engine performance. All the experiments were conducted at a constant engine speed of 3000 rpm
Numerical calculations of turbulent recirculating heat transfer beyond two-dimensional back-steps and sudden pipe expansions
A. M. Gooray
Extensive results of numerical calculations for turbulent recirculating flow with heat transfer are presented. The geometries studied were two dimensional flows over rearward (backward)--facing steps and sudden pipe expansions. The computations described were performed using the k-epsilon, two equation model of turbulence. To yield better predictions of heat transfer, the standard model was improved, by developing algebraic approximations for Reynolds
Exhaust-gas recirculation for retrofit NOx control on natural gas engines. Topical report, January-April 1988
Data on exhaust-gas recirculation obtained from Tenneco Gas Transportation Company were reviewed and analyzed, and a basic EGR system design and cost estimate were developed. EGR can provide practical NOx reductions of up to 50% in 2-cycle natural gas engines. The amount of NO reduction achievable is dependent on the initial baseline NOx emissions of the engine. On the basis
Stocking density effects on production characteristics and body composition of market size cobia, Rachycentron canadum, reared in recirculating aquaculture systems
Technology Transfer Automated Retrieval System (TEKTRAN)
Production density in excess of a critical threshold can result in a negative relationship between stocking density and fish production. This study was conducted to evaluate production characteristics of juvenile cobia Rachycentron canadum, reared to market size in production-scale recirculating aq...
The effects of carbon dioxide on performance and histopathology of rainbow trout Oncorhynchus mykiss in water recirculation aquaculture systems
Technology Transfer Automated Retrieval System (TEKTRAN)
Chronic exposure to elevated levels of dissolved carbon dioxide (CO2) has been linked to reduced growth, physiological disturbances and negative health outcomes in intensively reared fish. Although pumping to a degassing tower can lower concentrations of dissolved CO2 in water recirculation aquacult...
Use of exhaust gas recirculation as a control approach for thermoacoustic instabilities
Ranalli, J.; Ferguson, D.
Investigation into exhaust gas recirculation (EGR) as a method for reducing costs of postcombustion carbon capture in gas turbine systems reveals that EGR offers potential applications as a control strategy for thermoacoustic instabilities. Introduction of EGR allows semi-independent variation of the operating parameter of flame temperature and characteristic flame length scales, known to play a primary role in the phase of the thermoacoustic coupling mechanism. Measurements were made showing the ability of EGR to reduce the amplitude of thermoacoustic oscillations over a range of operating conditions in a laboratory scale, swirled dump combustor, without affecting the flame temperature. Theoretical analysis was also performed to investigate the limitations on the ability of this approach to influence dynamics.
A system of air recirculation and antibacterial surface treatment in a surgical ward
Ayliffe, G. A. J.; Beard, M. A.; Filbey, J.
A system of surface treatment with an antibacterial agent and air recirculation through treated filters was set up in a 15-bedded surgical ward, using an adjacent 10-bedded ward as a control. Nasal, wound, and urinary cross-infection was studied in both wards for over one year. Total bacterial counts and counts of Staphylococcus pyogenes were made from settle plates and blanket sweep plates. After the installation of the system aerial contamination in the test ward was reduced appreciably more than in the control ward. The number of blankets contaminated with Staph. pyogenes was similar in both wards. There was no significant difference in wound, nasal, or urinary cross-infection between the two wards. PMID:13863501
Measurement and control of exhaust gas recirculation with an oxygen pumping device
Logothetis, E.M.; Soltis, R.E.
This patent describes an electrochemical device form measuring the percentage of exhaust gas recirculation (EGR) in an intake air and exhaust gas mixture of an internal combustion engine. It comprises: a first solid electrochemical pump cell having a first pair of opposed electrodes; a second solid electrochemical pump cell having a second pair of opposed electrodes; a supporting structure coupled to the first and second pump cells to form with them a restricted volume; an aperture for providing communication between the restricted volume and an ambient of the intake air and exhaust gas mixture; a first external circuit means; a second external circuit means; and a means coupled to the second pump cell for measuring the current flowing through the second pump cell.
Parameter choices for a muon recirculating linear accelerator from 5 to 63 GeV
Berg, J. S.
A recirculating linear accelerator (RLA) has been proposed to accelerate muons from 5 to 63 GeV for a muon collider. It should be usable both for a Higgs factory and as a stage for a higher energy collider. First, the constraints due to the beam loading are computed. Next, an expression for the longitudinal emittance growth to lowest order in the longitudinal emittance is worked out. After finding the longitudinal expression, a simplified model that describes the arcs and their approximate expression for the time of flight dependence on energy in those arcs is found. Finally, these results are used to estimate the parameters required for the RLA arcs and the linac phase.
Equibrium and Stability of the Brillouin Flow in Recirculating Planar Magnetron
NASA Astrophysics Data System (ADS)
Simon, D. H.; Lau, Y. Y.; Franzi, M.; Greening, G.; Gilgenbach, R. M.; Luginsland, J. W.
Simulation of the novel recirculating planar magnetron, RPM, has shown rapid formation of electron bunches in the inverted magnetron configuration. This bunching mechanism was recently simulated in a thin electron layer model, which exhibited negative, positive, and infinite mass behavior, depending on the magnitude and sign of the radial electric field. We analyze these properties for the relativistic, cylindrical Brillouin flow, to evaluate RPM startup. We make use of our recent discovery that the electrostatic potential and the vector potential satisfy a Buneman-Hartree like relation, and a Hull-cutoff like relation EVERYWHERE within the equilibrium Brillouin flow. This work was supported by AFOSR, L-3 Communications Electron Devices, and Northrop Grumman Corporation.
NASA Technical Reports Server (NTRS)
Naumann, R. J.
A summary of the Analytical Float Zone Experiment System (AFZES) concept is presented. The types of experiments considered for such a facility are discussed. Reports from various industrial producers and users of float zone material are presented. Special emphasis is placed on state-of-the-art developments in low gravity manufacturing and their applications to space processing.
Microgravity silicon zoning investigation
NASA Technical Reports Server (NTRS)
Kern, E. L.; Gill, G. L., Jr.
A resistance heated zoner, suitable for early zoning experiments with silicon, was designed and put into operation. The initial power usage and size was designed for an shown to be compatible with payload carriers contemplated for the Shuttle. This equipment will be used in the definition and development of flight experiments and apparatus for float zoning silicon and other materials in microgravity.
Climate Zones Robinson Projection
Columbia University
Climate Zones Africa ÇRobinson Projection Copyright 2007. The Trustees of Columbia University University. Population, Landscape, and Climate Estimates (PLACE). Further information available at: http://sedac.ciesin.columbia.edu/place/ Publish Date: 03/13/07 0 500 km Climate zones were taken from the K—ppen Climate Classification map
Directional migration of recirculating lymphocytes through lymph nodes via random walks.
Thomas, Niclas; Matejovicova, Lenka; Srikusalanukul, Wichat; Shawe-Taylor, John; Chain, Benny
Naive T lymphocytes exhibit extensive antigen-independent recirculation between blood and lymph nodes, where they may encounter dendritic cells carrying cognate antigen. We examine how long different T cells may spend in an individual lymph node by examining data from long term cannulation of blood and efferent lymphatics of a single lymph node in the sheep. We determine empirically the distribution of transit times of migrating T cells by applying the Least Absolute Shrinkage & Selection Operator (LASSO) or regularised S-LASSO to fit experimental data describing the proportion of labelled infused cells in blood and efferent lymphatics over time. The optimal inferred solution reveals a distribution with high variance and strong skew. The mode transit time is typically between 10 and 20 hours, but a significant number of cells spend more than 70 hours before exiting. We complement the empirical machine learning based approach by modelling lymphocyte passage through the lymph node insilico. On the basis of previous two photon analysis of lymphocyte movement, we optimised distributions which describe the transit times (first passage times) of discrete one dimensional and continuous (Brownian) three dimensional random walks with drift. The optimal fit is obtained when drift is small, i.e. the ratio of probabilities of migrating forward and backward within the node is close to one. These distributions are qualitatively similar to the inferred empirical distribution, with high variance and strong skew. In contrast, an optimised normal distribution of transit times (symmetrical around mean) fitted the data poorly. The results demonstrate that the rapid recirculation of lymphocytes observed at a macro level is compatible with predominantly randomised movement within lymph nodes, and significant probabilities of long transit times. We discuss how this pattern of migration may contribute to facilitating interactions between low frequency T cells and antigen presenting cells carrying cognate antigen. PMID:23028891
Directional Migration of Recirculating Lymphocytes through Lymph Nodes via Random Walks
Thomas, Niclas; Matejovicova, Lenka; Srikusalanukul, Wichat; Shawe-Taylor, John; Chain, Benny
Naive T lymphocytes exhibit extensive antigen-independent recirculation between blood and lymph nodes, where they may encounter dendritic cells carrying cognate antigen. We examine how long different T cells may spend in an individual lymph node by examining data from long term cannulation of blood and efferent lymphatics of a single lymph node in the sheep. We determine empirically the distribution of transit times of migrating T cells by applying the Least Absolute Shrinkage & Selection Operator () or regularised to fit experimental data describing the proportion of labelled infused cells in blood and efferent lymphatics over time. The optimal inferred solution reveals a distribution with high variance and strong skew. The mode transit time is typically between 10 and 20 hours, but a significant number of cells spend more than 70 hours before exiting. We complement the empirical machine learning based approach by modelling lymphocyte passage through the lymph node . On the basis of previous two photon analysis of lymphocyte movement, we optimised distributions which describe the transit times (first passage times) of discrete one dimensional and continuous (Brownian) three dimensional random walks with drift. The optimal fit is obtained when drift is small, i.e. the ratio of probabilities of migrating forward and backward within the node is close to one. These distributions are qualitatively similar to the inferred empirical distribution, with high variance and strong skew. In contrast, an optimised normal distribution of transit times (symmetrical around mean) fitted the data poorly. The results demonstrate that the rapid recirculation of lymphocytes observed at a macro level is compatible with predominantly randomised movement within lymph nodes, and significant probabilities of long transit times. We discuss how this pattern of migration may contribute to facilitating interactions between low frequency T cells and antigen presenting cells carrying cognate antigen. PMID:23028891
Earthquake supercycle in subduction zones controlled by the downdip width of the seismogenic zone
NASA Astrophysics Data System (ADS)
Herrend—rfer, Robert; van Dinther, Ylona; Gerya, Taras; Dalguer, Luis Angel
Supercycles describe a long-term cluster of megathrust earthquakes that consist of partial ruptures before a complete failure of a subduction zone segment (Sieh et al. 2008, Goldfinger et al. 2013). The controls on supercycles remain unclear, although structural or fault frictional heterogeneities were proposed (Sieh et al. 2008). We recognize that supercycles have been suggested in those subduction zones (Sieh et al. 2008, Goldfinger et al. 2013, Metois et al. 2014, Chlieh et al. 2014) for which the seismogenic zone downdip width is estimated (Heuret et al. 2011, Hayes et al. 2012, Hayes et al. 2013) to be larger than average. Here we assess this potential link between the seismogenic zone downdip width and supercycles. For this purpose we use the continuum-based seismo-mechanical model of megathrust earthquake cycles in subduction zones (Van Dinther et al. 2013), which was validated through a comparison against scaled analogue subduction experiments (Corbi et al. 2013). The two-dimensional numerical model setup consists of a visco-elastic wedge underthrusted by a rigid plate and a frictional boundary layer simulating the megathrust. In this boundary layer, we evaluate a non-associative Drucker-Prager plasticity with pressure dependent yield strength and a strongly rate-dependent friction formulation. The velocity-weakening seismogenic zone with a downdip width W is limited up-and downdip by velocity-strengthening regions. In our numerical models, an increasing seismogenic zone downdip width leads to a transition from ordinary cycles of similar sized complete ruptures to supercycles. For supercycles in wide seismogenic zones, we demonstrate how interseismic deformation accompanied by partial ruptures effectively increases the stress throughout the seismogenic zone until a crack-like superevent releases most of the accumulated stresses. Our findings suggest that supercycles are more likely to occur in subduction zones with a large seismogenic downdip width due to a larger potential strength excess. It takes longer and more events to reach a critical stress state in the center of wider seismogenic zones. We conclude that such stress evolution along the dip of a wide seismogenic zone is the simplest mechanism governing supercycles. Our results show that earthquake size variability during a supercycle can be purely explained by the along-dip evolution of stress heterogeneities within an up- and downdip bounded homogeneous seismogenic zone. Additional a priori complexities, like previously suggested structural or frictional heterogeneities (Sieh et al. 2008) are not required to generate supercycles, although they are expected to complicate our simplest explanation of supercycles. We suggest that larger than thus far observed earthquakes could occur as part of a supercycle in subduction zones with a large seismogenic zone downdip width.
Large Eddy Simulation of Transient Flow, Solidification, and Particle Transport Processes in Continuous-Casting Mold
NASA Astrophysics Data System (ADS)
Liu, Zhongqiu; Li, Linmin; Li, Baokuan; Jiang, Maofa
The current study developed a coupled computational model to simulate the transient fluid flow, solidification, and particle transport processes in a slab continuous-casting mold. Transient flow of molten steel in the mold is calculated using the large eddy simulation. An enthalpy-porosity approach is used for the analysis of solidification processes. The transport of bubble and non-metallic inclusion inside the liquid pool is calculated using the Lagrangian approach based on the transient flow field. A criterion of particle entrapment in the solidified shell is developed using the user-defined functions of FLUENT software (ANSYS, Inc., Canonsburg, PA). The predicted results of this model are compared with the measurements of the ultrasonic testing of the rolled steel plates and the water model experiments. The transient asymmetrical flow pattern inside the liquid pool exhibits quite satisfactory agreement with the corresponding measurements. The predicted complex instantaneous velocity field is composed of various small recirculation zones and multiple vortices. The transport of particles inside the liquid pool and the entrapment of particles in the solidified shell are not symmetric. The Magnus force can reduce the entrapment ratio of particles in the solidified shell, especially for smaller particles, but the effect is not obvious. The Marangoni force can play an important role in controlling the motion of particles, which increases the entrapment ratio of particles in the solidified shell obviously.
Seismic coupling and uncoupling at subduction zones
NASA Technical Reports Server (NTRS)
Ruff, L.; Kanamori, H.
Some of the correlations concerning the properties of subduction zones are reviewed. A quantitative global comparison of many subduction zones reveals that the largest earthquakes occur in zones with young lithosphere and fast convergence rates. Maximum earthquake size is directly related to the asperity distribution on the fault plane. This observation can be translated into a simple model of seismic coupling where the horizontal compressive stress between two plates is proportional to the ratio of the summed asperity area to the total area of the contact surface. Plate age and rate can control asperity distribution directly through the horizontal compressive stress associated with the vertical and horizontal velocities of subducting slabs. The basalt to eclogite phase change in the down-going oceanic crust may be largely responsible for the uncoupling of subduction zones below a depth of about 40 km.
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
16. UPPER PASSENGER LOADING ZONE, NOTE LOADING ZONE BELOW WITH TURN STILES - Jefferson National Expansion Memorial Arch, Mississippi River between Washington & Poplar Streets, Saint Louis, Independent City, MO
NASA Astrophysics Data System (ADS)
Bense, V. F.; Gleeson, T.; Loveless, S. E.; Bour, O.; Scibek, J.
Deformation along faults in the shallow crust (< 1 km) introduces permeability heterogeneity and anisotropy, which has an important impact on processes such as regional groundwater flow, hydrocarbon migration, and hydrothermal fluid circulation. Fault zones have the capacity to be hydraulic conduits connecting shallow and deep geological environments, but simultaneously the fault cores of many faults often form effective barriers to flow. The direct evaluation of the impact of faults to fluid flow patterns remains a challenge and requires a multidisciplinary research effort of structural geologists and hydrogeologists. However, we find that these disciplines often use different methods with little interaction between them. In this review, we document the current multi-disciplinary understanding of fault zone hydrogeology. We discuss surface- and subsurface observations from diverse rock types from unlithified and lithified clastic sediments through to carbonate, crystalline, and volcanic rocks. For each rock type, we evaluate geological deformation mechanisms, hydrogeologic observations and conceptual models of fault zone hydrogeology. Outcrop observations indicate that fault zones commonly have a permeability structure suggesting they should act as complex conduit-barrier systems in which along-fault flow is encouraged and across-fault flow is impeded. Hydrogeological observations of fault zones reported in the literature show a broad qualitative agreement with outcrop-based conceptual models of fault zone hydrogeology. Nevertheless, the specific impact of a particular fault permeability structure on fault zone hydrogeology can only be assessed when the hydrogeological context of the fault zone is considered and not from outcrop observations alone. To gain a more integrated, comprehensive understanding of fault zone hydrogeology, we foresee numerous synergistic opportunities and challenges for the discipline of structural geology and hydrogeology to co-evolve and address remaining challenges by co-locating study areas, sharing approaches and fusing data, developing conceptual models from hydrogeologic data, numerical modeling, and training interdisciplinary scientists.
Accelerating Large Data Analysis by Exploiting Regularities
David Ellsworth; Patrick J. Moran
We present techniques for discovering and exploiting regularity in large curvilinear data sets. The data can be based on a single mesh or a mesh composed of multiple submeshes (also known as zones). Multi-zone data are typical in Computational Fluid Dynamics (CFD) simulations. Regularities include axis-aligned rectilinear and cylindrical meshes as well as cases where one zone is equivalent to
NSDL National Science Digital Library
This illustration is an approximate representation of the planets in our solar system and their relation to what scientists call The Habitable Zone. The planet distances from the sun are measured in Astronomical Units (AU) and are not to scale.
NASA Technical Reports Server (NTRS)
Farmer, R. C.; Audeh, B. J.
A spectroscopic instrumentation system was developed which was used to measure temperature and concentration distributions in axisymmetric and two dimensional combusting flows. This measurement technique is known as zone radiometry.
Fractal generalized zone plates
Omel Mendoza-Yero; Mercedes FernÃndez-Alonso; Gladys MÚnguez-Vega; Jesºs Lancis; Vicent Climent; Juan A. Monsoriu
The construction of fractal generalized zone plates (FraGZPs) from a set of periodic diffractive optical elements with circular symmetry is proposed. This allows us to increase the number of foci of a conventional fractal zone plate (FraZP), keeping the self-similarity property within the axial irradiance. The focusing properties of these fractal diffractive optical elements for points not only along but
Using Lidar to Advance Critical Zone Science
NASA Astrophysics Data System (ADS)
Harpold, Adrian A.; Lyon, Steve W.; Marshall, Jill A.
Critical Zone (CZ) scientists study the interactions among soil, water, air, and living organisms that shape the Earth's surface. Lidar (light detection and ranging) has transformative potential to advance CZ science because the technology simultaneously measures geomorphic, hydrologic, and ecologic properties at high resolution (<10 centimeters) and over large extents (>100 square kilometers).
Volcanism and aseismic slip in subduction zones
Hemendra Acharya
The spatial and temporal relationship of volcanism to the occurrence of large earthquakes and convergent plate motion is examined. The number of volcanic eruptions per year in a convergent zone is found to be linearly related to the aseismic slip component of plate motion. If the aseismic slip rate is low (coupling between converging plates is strong), then the primary
EnginEEring ZonE "The Engineering Zone
Tobar, Michael
EnginEEring ZonE "The Engineering Zone will push the limits in collaborative learning and research, and empower people to change the world. "Winthrop Professor John Dell Dean, Faculty of Engineering, Computing and Mathematics #12;2 | nEw CEntury Campaign Ù EnginEEring ZonE #12;nEw CEntury Campaign Ù EnginEEring ZonE | 3
Direct determination of blood recirculation rate in hemodialysis by a conductivity method.
Bosc, J Y; LeBlanc, M; Garred, L J; Marc, J M; Foret, M; Babinet, F; Tetta, C; Canaud, B
Blood recirculation is one of the key factors of decreasing dialysis efficiency. Determination of recirculation rate (R) is necessary to optimize effective dialysis delivery and to monitor vascular access function. R can be directly measured by a conductivity method in paired filtration dialysis (PFD), a double-compartment hemodiafiltration system that permits direct access to plasma water via the ultrafiltration stream. Measurement of R, in this system, involves the first of two conductivity sensors integrated in a urea monitor (UMS, BelIco-Sorin, Mirandola, Italy), and two saline injections. The rise in conductivity (deltaC1) induced by a 2.7 ml bolus of hypertonic saline 20% (mg/dl) in the arterial line serves for calibration, and is followed by an equivalent injection into the venous line, giving rise to deltaC2. The ratio deltaC2/deltaC1 equals R. A comparison between R values obtained with this method and with the low-flow technique in 31 chronic dialysis patients during 138 PFD sessions is reported. Mean R+/-SD by the conductivity method was 5.1+/-2.0 and 5.7+/-2.0% after 65 and 155 minutes of PFD (correlation coefficient, r = 0.75), whereas it was 6.4+/-4.9% and 5.5+/-4.6% after 30 sec of low blood pump flow for urea and creatinine markers, respectively (r = 0.35). After 120 sec of low flow, mean R increased to 9.0+/-5.1 and 8.8+/-4.6% for urea and creatinine, respectively (r = 0.45). Considerable discrepancies were found in R values measured simultaneously with the two blood markers. Statistically significant differences were found between the two measurement modalities (blood-side and conductivity); the correlation coefficients (r) varied between 0.28 and 0.41. The observed differences in mean R results do not seem considerable from a clinical perspective. The best agreement between blood-side and conductivity R measurements was obtained with Rcreat after 30 sec of low flow. Overall, a wider distribution was found in R values from blood-side determinations, most likely consequent to variability in the dosing method. The conductivity method appears more accurate and simple in assessing total R, and can be readily automated and integrated into the dialysis machine. The authors, therefore, recommend evaluation of R using methods not based on chemical blood concentration values. PMID:9466504
LUX - a recirculating linac-based facility for ultrafast X-ray science
Corlett, J.N.; Barletta, W.A.; DeSantis, S.; Doolittle, L.; Fawley, W.M.; Heimann, P.; Leone, S.; Lidia, S.; Li, D.; Penn, G.; Ratti, A.; Reinsch, M.; Schoenlein, R.; Staples, J.; Stover, G.; Virostek, S.; Wan, W.; Wells, R.; Wilcox, R.; Wolski, A.; Wurtele, J.; Zholents, A.
We present recent developments in design concepts for LUX - a source of ultra-short synchrotron radiation pulses based on a recirculating superconducting linac. The source produces high-flux x-ray pulses with duration of 100 fs or less at a 10 kHz repetition rate, optimized for the study of ultra-fast dynamics across many fields of science [1]. Cascaded harmonic generation in free-electron lasers (FEL's) produces coherent radiation in the VUV-soft x-ray regime, and a specialized technique is used to compress spontaneous emission for ultra-short-pulse photon production in the 1-10 keV range. High-brightness electron bunches of 2-3 mm-mrad emittance at 1 nC charge in 30 ps duration are produced in an rf photocathode gun and compressed to 3 ps duration following an injector linac, and recirculated three times through a 1 GeV main linac. In each return path, independently tunable harmonic cascades are inserted to produce seeded FEL radiation in selected photon energy ranges from approximately 20 eV with a single stage of harmonic generation, to 1 keV with a four-stage cascade. The lattice is designed to minimize emittance growth from effects such as coherent synchrotron radiation (CSR), and resistive wall wakefields. Timing jitter between pump lasers and x-ray pulses is minimized by use of a stable optical master oscillator, distributing timing signals over actively stabilized fiber-optic, phase-locking all lasers to the master oscillator, and generating all rf signals from the master oscillator. We describe technical developments including techniques for minimizing power dissipation in a high repetition rate rf photocathode gun, beam dynamics in two injector configurations, independently tunable beamlines for VUV and soft x-ray production by cascaded harmonic generation, a fast kicker design, timing systems for providing synchronization between experimental pump lasers and the x-ray pulse, and beamline design for maintaining nm-scale density modulation.
Design, loading, and water quality in recirculating systems for low salinity finfish species at the USDA /ARS Sustainable Marine Aquaculture Systems facility (Fort Pierce, FL)
Technology Transfer Automated Retrieval System (TEKTRAN)
The USDA ARS Sustainable Marine Aquaculture System Facility was established by the USDA ARS in collaboration with Harbor Branch Oceanographic Institute / Florida Atlantic University to improve the efficiency and sustainability of inland warmwater marine fish culture in recirculating aquaculture syst...
Cattle Grazing Influence on a Mountain Riparian Zone
A combination of management and physical topographic con- straints caused cattle to concentrate on the riparian zone early in the grazing season in 1977 and 1978. A large percentage of cattle days and vegetation utilization on the riparfan zone occurred in the first 4 weeks of the grazing period. Utilization on herbaceous vegetation was 76 and 72% in 1977 and
Comparison of Lethal Zone Characteristics of Several Natural Fragmenting Warheads
Berko ZECEVIC; Alan CATOVIC; Jasmin TERZIC
Research of HE warheads lethal zone is very complex topic because of large number of controlled and independent, sometimes correlated, influencing factors. Capability for prediction of lethal zone is based on complexity of databases regarding natural fragmentation parameters, which should contain data about warhead body material characteristics, types of explosive charge, number, mass, initial velocity and spatial distribution of fragments,
Performance of a constructed wetland in treating brackish wastewater from commercial recirculating and super-intensive shrimp growout systems.
Shi, Yonghai; Zhang, Genyu; Liu, Jianzhong; Zhu, Yazhu; Xu, Jiabo
A recirculating aquaculture system was developed for treating Pacific white shrimp (Litopenaeus vannamei) production wastewater using an integrated vertical-flow (IVF) and five connected integrated horizontal flow (IHF) constructed wetlands as water treatment filters for mesohaline conditions (8.25-8.26 salinity). The constructed wetlands demonstrated the ability to reduce total nitrogen, total ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, total phosphorous, chemical oxygen demand, and total suspended solids to levels significantly lower than those in effluents from culture tanks. Various water quality parameters in the culture tanks were deemed suitable for shrimp culture. The actual ratio of wetland area (A(w)) to culture tank area (A(t)) was 1.1439, and the estimated optimal ratio A(w)/A(t) was approximately 1. The IVF-IHF wetlands showed flexibility and reliability in consistently removing the main pollutants from commercial recirculating and super-intensive shrimp growout systems throughout the culture period. PMID:21852127
Improving methane production and phosphorus release in anaerobic digestion of particulate saline sludge from a brackish aquaculture recirculation system.
Zhang, Xuedong; Ferreira, Rui B; Hu, Jianmei; Spanjers, Henri; van Lier, Jules B
In this study, batch tests were conducted to examine the effects of trehalose and glycine betaine as well as potassium on the specific methanogenic activity (SMA), acid and alkaline phosphatase activity of anaerobic biomass and phosphorus release in anaerobic digestion of saline sludge from a brackish recirculation aquaculture system. The results of ANOVA and Tukey's HSD (honestly significant difference) tests showed that glycine betaine and trehalose enhanced SMA of anaerobic biomass and reactive phosphorus release from the particulate waste. Moreover, SMA tests revealed that methanogenic sludge, which was long-term acclimatized to a salinity level of 17 g/L was severely affected by the increase in salinity to values exceeding 35 g/L. Addition of compatible solutes, such as glycine betaine and trehalose, could be used to enhance the specific methane production rate and phosphorus release in anaerobic digestion from particulate organic waste produced in marine or brackish aquaculture recirculation systems. PMID:24785791
Fluid pathways in subduction zones
NASA Astrophysics Data System (ADS)
Spiegelman, M. W.; van Keken, P. E.; Hacker, B. R.
A large amount of water captured in the oceanic crust and mantle is recycled in subduction zones. Upon compaction and heating most fluids are expelled, but a significant amount of water can be carried in hydrated mineral phases and point defects. While the qualitative role of volatiles and dehydration reactions is well appreciated in the mechanisms for intermediate depth seismicity, mantle wedge melting and arc volcanism, the quantitative details of the metamorphic reactions and the pathways of fluids and melts in the slab are poorly understood. We provide finite element models, combined with thermodynamic and mineralogical constraints, to estimate the water release and migration from the subducting slab to overlying arc. We use models from a selection of warm (e.g., Cascadia), cold (Central Honshu) and intermediate (Nicaragua) subduction zones, using slab geometries constrained from seismological observations. The fluid release is predicted from the breakdown of hydrated phases in sediments, oceanic crust and slab mantle. We use newly developed high resolution models for the flow of these released fluids that take into account permeability and compaction pressures. While the detailed structure depends on the chosen rheology and permeability, we find that for reasonable assumptions of permeability, a significant amount of fluids can travel through the wedge along nearly vertical pathways at rates and paths, consistent with geochronological and geochemical constraints. For models considered to date, we find that the principal source of fluids that feed the wedge come from the hydrated oceanic crust and particularly the hydrated slab mantle. Fluids released from the sediments and shallow crust, tend to travel along high permeability zones in the subducting slab before being released to hydrate the cold corner of subduction zones, suggesting that the cold and hydrated forearc region that is imaged in many subduction zones is maintained by an active hydrological cycle. For these materials to be involved in wedge melting, however, would require entrainment of the rehydrated material into the wedge flow. Current fluid flow models only include dehydration reactions and not melting, thus fluid pathways are for the hydrous fluid only. We plan to add a reactive flow formulation to these models that includes consistent hydration, dehydration and melting reactions, thus allowing for a more complete description of chemical transport through the subduction system. Nicaragua Model
The U Plant geographic zone (UPZ) occupies 0.83 square kilometers on the Hanford Site Central Plateau (200 Area). It encompasses the U Plant canyon (221-U Facility), ancillary facilities that supported the canyon, soil waste sites, and underground pipelines. The UPZ cleanup initiative coordinates the cleanup of the major facilities, ancillary facilities, waste sites, and contaminated pipelines (collectively identified as ''cleanup items'') within the geographic zone. The UPZ was selected as a geographic cleanup zone prototype for resolving regulatory, technical, and stakeholder issues and demonstrating cleanup methods for several reasons: most of the area is inactive, sufficient characterization information is available to support decisions, cleanup of the high-risk waste sites will help protect the groundwater, and the zone contains a representative cross-section of the types of cleanup actions that will be required in other geographic zones. The UPZ cleanup demonstrates the first of 22 integrated zone cleanup actions on the Hanford Site Central Plateau to address threats to groundwater, the environment, and human health. The UPZ contains more than 100 individual cleanup items. Cleanup actions in the zone will be undertaken using multiple regulatory processes and decision documents. Cleanup actions will include building demolition, waste site and pipeline excavation, and the construction of multiple, large engineered barriers. In some cases, different cleanup actions may be taken at item locations that are immediately adjacent to each other. The cleanup planning and field activities for each cleanup item must be undertaken in a coordinated and cohesive manner to ensure effective execution of the UPZ cleanup initiative. The UPZ zone cleanup implementation plan (ZCIP) was developed to address the need for a fundamental integration tool for UPZ cleanup. As UPZ cleanup planning and implementation moves forward, the ZCIP is intended to be a living document that will provide a focal point for integrating UPZ actions, including field cleanup activities, waste staging and handling, and post-cleanup monitoring and institutional controls.
William J. Golz; Shulin Chen; Ronald F. Malone
Over the past decade, the environmental impact of wastes discharged from high-density flow-through fish-production systems has been viewed with increasing concern. Recirculating aquaculture systems are gaining wider acceptance because of their ability to reduce waste discharges, improve quality control, and reduce costs. The crucial processes that must be addressed in treating recirculating water are solids capture, biofiltration, aeration, degasification, and
77 FR 19740 - Water Sources for Long-Term Recirculation Cooling Following a Loss-of-Coolant Accident
Federal Register 2010, 2011, 2012, 2013, 2014
The U.S. Nuclear Regulatory Commission (NRC or the Commission) is issuing a revision to Regulatory Guide (RG) 1.82, ``Water Sources for Long-Term Recirculation Cooling Following a Loss-of-Coolant Accident.'' RG 1.82 describes methods that the NRC staff considers acceptable to implement requirements regarding the sumps and suppression pools that provide water sources for emergency core cooling,......
Production Characteristics and Body Composition of Juvenile Cobia Fed Three Different Commercial Diets in Recirculating Aquaculture Systems
Charles R. Weirich; Paul S. Wills; Richard M. Baptiste; Marty A. Riche
The effect of feeding three commercial diets on production characteristics and body composition of juvenile cobia Rachycentron canadum reared using recirculating aquaculture systems (RASs) was assessed in a 56-d growth trial. Juvenile cobia (mean weight Ý SE, 29.2 Ý 0.7 g) were stocked into three 8-m tanks in each of four RASs at an initial density of 1.2 kg\\/m. After
Performance of a constructed wetland in treating brackish wastewater from commercial recirculating and super-intensive shrimp growout systems
Yonghai Shi; Genyu Zhang; Jianzhong Liu; Yazhu Zhu; Jiabo Xu
A recirculating aquaculture system was developed for treating Pacific white shrimp (Litopenaeus vannamei) production wastewater using an integrated vertical-flow (IVF) and five connected integrated horizontal flow (IHF) constructed wetlands as water treatment filters for mesohaline conditions (8.258.26 salinity). The constructed wetlands demonstrated the ability to reduce total nitrogen, total ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, total phosphorous, chemical oxygen demand,
Effects of Yucca shidigera Extract on Water Quality and Fish Growth in Recirculating-Water Aquaculture Systems
James H. Tidwell; Carl D. Webster; Julia A. Clark; Daniel H. Yancey
In livestock industries such as poultry and swine, an extract of the Yucca shidigera plant has shown promise in controlling ammonia buildup in production facilities. In three trials, effects of Y. shidigera extract on ammonia levels and fish growth in recirculating-water aquaculture systems were evaluated. When added to in vitro ammonia solutions, extract concentrations of 0.043% and 0.43% caused a
Development and design of a fluidized bed\\/upflow sand filter configuration for use in recirculating aquaculture systems
A fluidized bed\\/upflow sand filter configuration, was developed and designed for utilization in recirculating aquaculture system, specifically the soft-shell crab and soft-shell crawfish industries. These filters were selected and designed because of their ability to withstand clogging and still maintain high levels of water quality for aquaculture production. The effectiveness of sand grain size was used to evaluate fluidized bed
Evaluation of air-lift pump capabilities for water delivery, aeration, and degasification for application to recirculating aquaculture systems
J. Clay Loyless; Ronald F Malone
A methodology is demonstrated for evaluating the feasibility of using air-lift pumps for water movement, aeration, and degasification in a recirculating aquaculture system. A set of empirical equations are presented modeling the performance of a 5.08-cm (2?) diameter air-lift submerged 91.44 cm (36?) with a 15.24-cm (6?) lift operated at 28142 l min?1 (15 scfm) of air injection. A steady
Effects of Biofilter\\/Culture Tank Volume Ratios on Productivity of a Recirculating Fish\\/Vegetable Co-Culture System
M. R. McMurtry; D. C. Sanders; J. D. Cure; R. G. Hodson
The effects of four biofilter volume (BFV)\\/culture tank volume ratios (0.67\\/1, 1.00\\/1, 1.50\\/1, and 2.25\\/1) on biofilter function were examined in a recirculating fish\\/vegetable production system in a greenhouse. Sand beds served as biofilters, as substrate for vegetable growth, and as location for decomposition of waste solids. No fertilizer was used. Three experiments were conducted over the course of one
Anaerobic Ammonium-Oxidizing (Anammox) Bacteria and Associated Activity in Fixed-Film Biofilters of a Marine Recirculating Aquaculture System
Yossi Tal; Joy E. M. Watts; Harold J. Schreier
Microbial communities in the biological filter and waste sludge compartments of a marine recirculating aqua- culture system were examined to determine the presence and activity of anaerobic ammonium-oxidizing (anammox) bacteria. Community DNA was extracted from aerobic and anaerobic fixed-film biofilters and the anaerobic sludge waste collection tank and was analyzed by amplifying 16S rRNA genes by PCR using anammox-selective and
Semi-continuous anaerobic co-digestion of cow manure and steam-exploded Salix with recirculation of liquid digestate.
Estevez, Maria M; Sapci, Zehra; Linjordet, Roar; Schn■rer, Anna; Morken, John
The effects of recirculating the liquid fraction of the digestate during mesophilic anaerobic co-digestion of steam-exploded Salix and cow manure were investigated in laboratory-scale continuously stirred tank reactors. An average organic loading rate of 2.6 g VS L(-1) d(-1) and a hydraulic retention time (HRT) of 30 days were employed. Co-digestion of Salix and manure gave better methane yields than digestion of manure alone. Also, a 16% increase in the methane yield was achieved when digestate was recirculated and used instead of water to dilute the feedstock (1:1 dilution ratio). The reactor in which the larger fraction of digestate was recirculated (1:3 dilution ratio) gave the highest methane yields. Ammonia and volatile fatty acids did not reach inhibitory levels, and some potentially inhibitory compounds released during steam explosion (i.e., furfural and 5-hydroxy methyl furfural) were only detected at trace levels throughout the entire study period. However, accumulation of solids, which was more pronounced in the recycling reactors, led to decreased methane yields in those systems after three HRTs. Refraining from the use of fresh water to dilute biomass with a high-solids content and obtaining a final digestate with increased dry matter content might offer important economic benefits in full-scale processes. To ensure long-term stability in such an approach, it would be necessary to optimize separation of the fraction of digestate to be recirculated and also perform proper monitoring to avoid accumulation of solids. PMID:24534902
Effects of a saturated layer and recirculation on nitrogen treatment performances of a single stage Vertical Flow Constructed Wetland (VFCW).
Prigent, S; Paing, J; Andres, Y; Chazarenc, F
Upgrades to enhance nitrogen removal were tested in a 2 year old pilot vertical flow constructed wetland in spring and summer periods. The effects of a saturated layer and of recirculation were tested in particular. Two pilots (L = 2 m, W = 1.25 m, H = 1.2 m), filled with expanded schist (Mayennite(Û)), were designed with hydraulic saturated layers of 20 and 40 cm at the bottom. Each pilot was fed with raw domestic wastewater under field conditions according to a hydraulic load of 15-38 cm d(-1) (i.e. 158-401 g COD (chemical oxygen demand) m(-2) d(-1)) and to recirculation rates ranging from 0% up to 150%. The initial load during the first 2 years of operation resulted in an incomplete mineralized accumulated sludge leading to total suspended solids (TSS), COD and biochemical oxygen demand (BOD5) release. A 40 cm hydraulic saturated layer enabled an increase of 5-10% total nitrogen (TN) removal compared to a 20 cm saturated layer. Recirculation allowed the dilution of raw wastewater and enhanced nitrification in a single stage. A design of 1.8 mý pe(-1) (48 cm d(-1), 191 g COD m(-2) d(-1)) with a 40 cm saturated layer and 100% recirculation enabled the French standard D4 (35 mg TSS L(-1), 125 mg COD L(-1), 25 mg BOD5 L(-1)), nitrogen concentrations below 20 mg TKN (total Kjeldahl nitrogen) L(-1) and 50 mg TN L(-1), to be met. PMID:24135093
Development of a hybrid k-epsilon turbulence model for swirling recirculating flows under moderate to strong swirl intensities
Keh-Chin Chang; Ching-Shun Chen
A hybrid k-epsilon turbulence model, based on the concept that the modification of anisotropic effects should not be made in the flow regions inherent to small streamline curvatures, has been developed and examined with the swirling recirculating flows, with the swirl levels ranging from 0.6 to 1.23 in an abrupt pipe expansion. A fairly satisfactory agreement of model predictions with
Contribution of 3-D time-lapse ERT to the study of leachate recirculation in a landfill
Clement, R., E-mail: firstname.lastname@example.com [Laboratoire d'Etude des Transferts en Hydrologie et Environnement (LTHE, UMR 5564, CNRS, INPG, IRD, UJF), B.P. 53, 38041 Grenoble Cedex 9 (France); Grenoble Universite, B.P. 53, 38041 Grenoble Cedex 9 (France); Oxarango, L. [Laboratoire d'Etude des Transferts en Hydrologie et Environnement (LTHE, UMR 5564, CNRS, INPG, IRD, UJF), B.P. 53, 38041 Grenoble Cedex 9 (France); Grenoble Universite, B.P. 53, 38041 Grenoble Cedex 9 (France); Descloitres, M. [Laboratoire d'Etude des Transferts en Hydrologie et Environnement (LTHE, UMR 5564, CNRS, INPG, IRD, UJF), B.P. 53, 38041 Grenoble Cedex 9 (France)
Leachate recirculation is a key process in the operation of municipal waste landfills as bioreactors. It aims at increasing the moisture content to optimise the biodegradation. Because waste is a very heterogeneous and anisotropic porous media, the geometry of the leachate plume recirculation is difficult to delineate from the surface at the scale of the bioreactor site. In this study, 3-D time-lapse electrical resistivity tomography (ERT) was used to obtain useful information for understanding leachate recirculation hydrodynamics. The ERT inversion methodology and the electrode arrays were optimised using numerical modelling simulating a 3-D leachate injection scenario. Time-lapse ERT was subsequently applied at the field scale during an experimental injection. We compared ERT images with injected volumes to evaluate the sensitivity of time-lapse ERT to delineate the plume migration. The results show that time-lapse ERT can accomplish the following: (i) accurately locate the injection plume, delineating its depth and lateral extension; (ii) be used to estimate some hydraulic properties of waste.
Effect of heat recirculation on the self-sustained catalytic combustion of propane/air mixtures in a quartz reactor
Scarpa, A. [Dipartimento di Ingegneria Chimica, Universita degli Studi di Napoli ''Federico II'', P.le V. Tecchio 80, 80125 Naples (Italy); Department of Chemical Engineering, Center for Catalytic Science and Technology (CCST), and Center for Composite Materials (CCM), University of Delaware, 150 Academy Street, Newark, DE 19716 (United States); Pirone, R. [Istituto di Ricerche sulla Combustione-CNR, P.le V. Tecchio 80, 80125 Naples (Italy); Russo, G. [Dipartimento di Ingegneria Chimica, Universita degli Studi di Napoli ''Federico II'', P.le V. Tecchio 80, 80125 Naples (Italy); Vlachos, D.G. [Department of Chemical Engineering, Center for Catalytic Science and Technology (CCST), and Center for Composite Materials (CCM), University of Delaware, 150 Academy Street, Newark, DE 19716 (United States)
The self-sustained catalytic combustion of propane is experimentally studied in a two-pass, quartz heat-recirculation reactor (HRR) and compared to that in a no (heat) recirculation reactor (NRR). Structured monolithic reactors with Pt/{gamma}-Al{sub 2}O{sub 3}, LaMnO{sub 3}/{gamma}-Al{sub 2}O{sub 3}, and Pt doped perovskite catalysts have been compared in the HRR and NRR configurations. Heat recirculation enhances combustion stability, by widening the operating window of self-sustained operation, and changes the mode of stability loss from blowout to extinction. It is found that thermal shields (upstream and downstream of the monolith) play no role in the stability of a HRR but increase the stability of a NRR. The stability of a HRR follows this trend: Pt/{gamma}-Al{sub 2}O{sub 3} > doped perovskite > LaMnO{sub 3}/{gamma}-Al{sub 2}O{sub 3}. Finally, a higher cell density monolith enlarges the operating window of self-sustained combustion, and allows further increase of the power density of the process. (author)
Recirculation or artificial aeration in vertical flow constructed wetlands: a comparative study for treating high load wastewater.
Foladori, Paola; Ruaben, Jenny; Ortigara, Angela R C
Vertical subsurface-flow constructed wetlands at pilot-scale have been applied to treat high hydraulic and organic loads by implementing the following configurations: (1) intermittent recirculation of the treated wastewater from the bottom to the top of the bed, (2) intermittent artificial aeration supplied at the bottom of the bed and (3) the combination of both. These configurations were operated with a saturated bottom layer for a 6h-treatment phase, followed by a free drainage phase prior to a new feeding. COD removal efficiency was 85-90% in all the configurations and removed loads were 54-70 gCOD m(-2)d(-1). The aerated and recirculated wetland resulted in a higher total nitrogen removal (8.6 gN m(-2)d(-1)) due to simultaneous nitrification/denitrification, even in the presence of intermittent aeration (6.8 Nm(3)m(-2)d(-1)). The extra investment needed for implementing aeration/recirculation would be compensated for by a reduction of the surface area per population equivalent, which decreased to 1.5m(2)/PE. PMID:24128403
Cluster formation and drag reduction-proposed mechanism of particle recirculation within the partition column of the bottom spray fluid-bed coater.
Wang, Li Kun; Heng, Paul Wan Sia; Liew, Celine Valeria
Bottom spray fluid-bed coating is a common technique for coating multiparticulates. Under the quality-by-design framework, particle recirculation within the partition column is one of the main variability sources affecting particle coating and coat uniformity. However, the occurrence and mechanism of particle recirculation within the partition column of the coater are not well understood. The purpose of this study was to visualize and define particle recirculation within the partition column. Based on different combinations of partition gap setting, air accelerator insert diameter, and particle size fraction, particle movements within the partition column were captured using a high-speed video camera. The particle recirculation probability and voidage information were mapped using a visiometric process analyzer. High-speed images showed that particles contributing to the recirculation phenomenon were behaving as clustered colonies. Fluid dynamics analysis indicated that particle recirculation within the partition column may be attributed to the combined effect of cluster formation and drag reduction. Both visiometric process analysis and particle coating experiments showed that smaller particles had greater propensity toward cluster formation than larger particles. The influence of cluster formation on coating performance and possible solutions to cluster formation were further discussed. PMID:25556353
A study on the optimal hydraulic loading rate and plant ratios in recirculation aquaponic system.
Endut, Azizah; Jusoh, A; Ali, N; Wan Nik, W B; Hassan, A
The growths of the African catfish (Clarias gariepinus) and water spinach (Ipomoea aquatica) were evaluated in recirculation aquaponic system (RAS). Fish production performance, plant growth and nutrient removal were measured and their dependence on hydraulic loading rate (HLR) was assessed. Fish production did not differ significantly between hydraulic loading rates. In contrast to the fish production, the water spinach yield was significantly higher in the lower hydraulic loading rate. Fish production, plant growth and percentage nutrient removal were highest at hydraulic loading rate of 1.28 m/day. The ratio of fish to plant production has been calculated to balance nutrient generation from fish with nutrient removal by plants and the optimum ratio was 15-42 gram of fish feed/m(2) of plant growing area. Each unit in RAS was evaluated in terms of oxygen demand. Using specified feeding regime, mass balance equations were applied to quantify the waste discharges from rearing tanks and treatment units. The waste discharged was found to be strongly dependent on hydraulic loading rate. PMID:19819130
Formation of disinfection byproducts in a recirculating mariculture system: emerging concerns.
Qiang, Zhimin; Zhang, Haiting; Dong, Huiyu; Adams, Craig; Luan, Gang; Wang, Lei
Disinfection is commonly employed in recirculating mariculture systems (RMS) to control animal diseases and improve seawater quality; however, little is known about the occurrence of disinfection byproducts (DBPs) formed in such RMS. Beijing Aquarium is a typical RMS with artificially prepared seawater and mainly adopts a decentralized treatment strategy for different animal tanks, including sand filtration, foam fractionation, and disinfection (O3, UV, and O3/ClO2). This study reveals that the adopted disinfection processes were highly effective in controlling marine heterotrophic bacteria; however, some concerns were raised on the formation of various kinds of DBPs, including secondary oxidants, inorganic oxyanions, and hazardous organic species. Free chlorine and free bromine were generated from ozonation at health-relevant concentrations. High concentrations of BrO3(-) and ClO3(-) were formed in mammal tanks, which exceeded the USEPA-regulated maximum contaminant level (MCL) for drinking water by 19-25 and 52-54 times, respectively. Extremely high concentrations of NO3(-) were detected in mammal tanks, which considerably exceeded the MCL regulated by the Sea Water Quality Standard of China for the mariculture industry (Class II) by about 1100 times. Undoubtedly, the presence of various DBPs poses serious health threats to aquarium animals. To solve these problems, potential control measures for DBPs are proposed. PMID:25573452
Towards Accurate Prediction of Turbulent, Three-Dimensional, Recirculating Flows with the NCC
NASA Technical Reports Server (NTRS)
Iannetti, A.; Tacina, R.; Jeng, S.-M.; Cai, J.
The National Combustion Code (NCC) was used to calculate the steady state, nonreacting flow field of a prototype Lean Direct Injection (LDI) swirler. This configuration used nine groups of eight holes drilled at a thirty-five degree angle to induce swirl. These nine groups created swirl in the same direction, or a corotating pattern. The static pressure drop across the holes was fixed at approximately four percent. Computations were performed on one quarter of the geometry, because the geometry is considered rotationally periodic every ninety degrees. The final computational grid used was approximately 2.26 million tetrahedral cells, and a cubic nonlinear k - epsilon model was used to model turbulence. The NCC results were then compared to time averaged Laser Doppler Velocimetry (LDV) data. The LDV measurements were performed on the full geometry, but four ninths of the geometry was measured. One-, two-, and three-dimensional representations of both flow fields are presented. The NCC computations compare both qualitatively and quantitatively well to the LDV data, but differences exist downstream. The comparison is encouraging, and shows that NCC can be used for future injector design studies. To improve the flow prediction accuracy of turbulent, three-dimensional, recirculating flow fields with the NCC, recommendations are given.
Development of high-efficiency molecular adsorbent recirculating system: preliminary report.
Marangoni, Roberto; Bellati, Giorgio; Castelli, Alessandro; Romagnoli, Elisabetta
Molecular Adsorbent Recirculating System (MARS) is a liver support system widely employed in the treatment of liver failure. The method is normally well tolerated. To develop a liver support system combining high efficiency and tolerability, we modified the MARS albumin circuit with the insertion of double adsorption units in parallel. Four patients have been treated with this modified method (high-efficiency MARS, HE MARS): two had very high serum bilirubin and two had very high total bile acids. After a single MARS session bilirubin was reduced more with HE MARS than standard MARS (from 27.6 to 52.3% in patient A and from 27.9 to 49.1% in patient B), and bile acid reduction increased from 40 to 59.8% in patient C and from 39.9 to 60% in patient D. The results of this preliminary investigation in only a very small number of patients do support the possibility of developing a liver support system that combines good tolerability and high efficacy. PMID:24392970
The design of an optimized portable artificial kidney system using recirculation and regeneration of dialysate.
Bigsby, R J; Rider, R J; Blount, G N
This paper is intended as an overview of the research carried out at Coventry University in the design of a portable artificial kidney system. It was seen that the key to the problem was the reduction in dialysate volume, and so it was decided to develop a prototype that would utilize the regeneration and recirculation of a small volume of dialysate. A prototype system has been produced and used to simulate a dialysis session. Activated carbon was used as a sorbent for the regeneration of the dialysate, circulating in a closed loop. For the purpose of this work, the adsorption of urea was investigated as this is, volumetrically, the major solute to be removed. Peltier effect cooling was used to vary the dialysate temperature down to 2 degrees C, as activated carbon will adsorb greater amounts of urea at lower temperatures. A series of tests was then carried out to investigate the effect of dialysate temperature, flowrate and volume on the amount of urea that could be dialysed. From the experimental results, a model of the system was derived, which made it possible to determine the implications of different operating conditions on the overall mass and size of a portable dialysis system. The output of this model was then used to establish a design specification and produce an optimum design solution for the system. PMID:9803156
Measurement and control of exhaust gas recirculation with an oxygen pumping device
Logothetis, E.M.; Soltis, R.E.
This patent describes an electrochemical device for measuring the percentage of exhaust gas recirculation (EGR) in an intake air and exhaust gas mixture of an internal combustion engine. It comprises: a generally planar first electrochemical pump cell including a relatively dense ZrO{sub 2} platelet with porous platinum electrodes on two sides of the platelet; a first porous ZrO{sub 2} layer deposited on one electrode of the first pump cell; a generally planar second electrochemical pump cell including a first porous platinum electrode, a second porous ZrO{sub 2} layer and a second porous platinum electrode deposited successively on the first porous ZrO{sub 2} layer; a second cell external circuit means coupled to the second pump cell for passing a constant current through the second pump cell so that the second electrode is biased positively causing a portion of the oxygen molecules inside the first porous ZrO{sub 2} layer to be pumped out by the current flowing through the second pump cell; a first cell external circuit means coupled to the first pump cell so that the exposed electrode is biased positively; a third external circuit means coupled to the first pump cell for measuring the current flowing through the first pump cell.
Dynamic instabilities in spark-ignited combustion engines with high exhaust gas recirculation
Daw, C Stuart [ORNL] [ORNL; FINNEY, Charles E A [ORNL] [ORNL
We propose a cycle-resolved dynamic model for combustion instabilities in spark-ignition engines operating with high levels of exhaust gas recirculation (EGR). High EGR is important for increasing fuel efficiency and implementing advanced low-emission combustion modes such as homogenous charge compression ignition (HCCI). We account for the complex combustion response to cycle-to-cycle feedback by utilizing a global probability distribution that describes the pre-spark state of in-cylinder fuel mixing. The proposed model does a good job of simulating combustion instabilities observed in both lean-fueling engine experiments and in experiments where nitrogen dilution is used to simulate some of the combustion inhibition of EGR. When used to simulate high internal EGR operation, the model exhibits a range of global bifurcations and chaos that appear to be very robust. We use the model to show that it should be possible to reduce high EGR combustion instabilities by switching from internal to external EGR. We also explain why it might be helpful to deliberately stratify the fuel in the pre-spark gas mixture. It might be possible to extend the simple approach used in this model to other chemical reaction systems with spatial inhomogeneity.
A polarimeter for GeV protons of recirculating synchrotron beams
NASA Astrophysics Data System (ADS)
Bauer, F.; B■Ôer, K.; EDDA Collaboration
A polarimeter for use in recirculating beams of proton synchrotrons with energies from 300 MeV up to several GeV has been developed. The polarimetry is based on the asymmetry measurement of elastic p?p scattering on an internal CH 2 fiber target. The forward going protons are detected with two scintillator systems on either side of the beam pipe close to the angle ?f of maximum analyzing power AN. Each one operates in coincidence with a broad (? ?b=21.4¯), segmented detector system for the recoil proton of kinematically varying direction ?b; this position resolution is also used for a concurrent measurement of the p?C and nonelastic p?p background. The CH 2 fiber can be replaced by a carbon fiber for detailed background studies; "false" asymmetries are accounted for with a rotation of the polarimeter around the beam axis. Polarimetry has been performed in the internal beam of the Cooler Synchrotron COSY at fixed energies as well as during proton acceleration across depolarizing or spin flipping resonances. With luminosities in the order of 10 30 cm -2 s -1, count rates allow precise polarimetry within 10 min (6-10 h) at fixed energies (over the whole acceleration ramp).
An assessment of the characteristics of yard trimmings and recirculated yard trimmings used in biowaste composting.
Lµpez, Marga; Soliva, Montserrat; MartÚnez-FarrÕ, F Xavier; BonmatÚ, August; Huerta-Pujol, Oscar
The aim of this research was to characterise samples of yard trimmings (YT) and recirculated yard trimmings (RYT) that are used to co-compost organic fraction of municipal solid waste (OFMSW) taken from 18 composting facilities in Catalonia (NE Spain), to determine their contribution in the composting process, and to highlight the advantages and disadvantages of reusing RYT. We found significant differences between the characteristics of the two materials. RYT had higher pH levels, electrical conductivity, and organic and ammonium nitrogen content than YT. Nutrient content also shows an increment from YT to RYT, and in the case of P and K, this variation can be attributed to an exogenous source rather than the relative concentration during the composting process. We also found significant differences in particle size distribution and bulk density. From the results, it can be assumed that RYT could be reused in the composting process if OFMSW, YT, and RYT are used in the correct quantities to balance the mixture but they cannot totally replace the features of YT. PMID:19811908
Use of Multipass Recirculation and Energy Recovery In CW SRF X-FEL Driver Accelerators
Douglas, David; Akers, Walt; Benson, Stephen V.; Biallas, George; Blackburn, Keith; Boyce, James; Bullard, Donald; Coleman, James; Dickover, Cody; Ellingsworth, Forrest; Evtushenko, Pavel; Fisk, Sally; Gould, Christopher; Gubeli, Joseph; Hannon, Fay; Hardy, David; Hernandez-Garcia, Carlos; Jordan, Kevin; Klopf, John; Kortze, J.; Legg, Robert; Li, Rui; Marchlik, Matthew; Moore, Steven W.; Neil, George; Powers, Thomas; Sexton, Daniel; Shin, Ilkyoung; Shinn, Michelle D.; Tennant, Christopher; Terzic, Balsa; Walker, Richard; Williams, Gwyn P.; Wilson, G.; Zhang, Shukui
We discuss the use of multipass recirculation and energy recovery in CW SRF drivers for short wavelength FELs. Benefits include cost management (through reduced system footprint, required RF and SRF hardware, and associated infrastructure - including high power beam dumps and cryogenic systems), ease in radiation control (low drive beam exhaust energy), ability to accelerate and deliver multiple beams of differing energy to multiple FELs, and opportunity for seamless integration of multistage bunch length compression into the longitudinal matching scenario. Issues include all those associated with ERLs compounded by the challenge of generating and preserving the CW electron drive beam brightness required by short wavelength FELs. We thus consider the impact of space charge, BBU and other environmental wakes and impedances, ISR and CSR, potential for microbunching, intra-beam and beam-residual gas scattering, ion effects, RF transients, and halo, as well as the effect of traditional design, fabrication, installation and operational errors (lattice aberrations, alignment, powering, field quality). Context for the discussion is provided by JLAMP, the proposed VUV/X-ray upgrade to the existing Jefferson Lab FEL.
Observations on Side-Swimming Rainbow Trout in Water Recirculation Aquaculture Systems
Good, Christopher; Davidson, John; Kinman, Christin; Kenney, P. Brett; BÌverfjord, Grete; Summerfelt, Steven
Abstract During a controlled 6-month study using six replicated water recirculation aquaculture systems (WRASs), it was observed that Rainbow Trout Oncorhynchus mykiss in all WRASs exhibited a higher-than-normal prevalence of side swimming (i.e., controlled, forward swimming but with misaligned orientation such that the fish's sagittal axis is approximately parallel to the horizontal plane). To further our understanding of this abnormality, a substudy was conducted wherein side swimmers and normally swimming fish were selectively sampled from each WRAS and growth performance (length, weight), processing attributes (fillet yield, visceral index, ventrum [i.e., thickness of the ventral belly flap] index), blood gas and chemistry parameters, and swim bladder morphology and positioning were compared. Side swimmers were found to be significantly smaller in length and weight and had less fillet yield but higher ventrum indices. Whole-blood analyses demonstrated that, among other things, side swimmers had significantly lower whole-blood pH and higher Pco 2. Side swimmers typically exhibited swim bladder malformations, although the positive predictive value of this subjective assessment was only 73%. Overall, this study found several anatomical and physiological differences between side-swimming and normally swimming Rainbow Trout. Given the reduced weight and fillet yield of market-age side swimmers, producers would benefit from additional research to reduce side-swimming prevalence in their fish stocks. Received March 20, 2014; accepted May 20, 2014 PMID:25250476
Case study of landfill leachate recirculation using small-diameter vertical wells.
Jain, Pradeep; Ko, Jae Hac; Kumar, Dinesh; Powell, Jon; Kim, Hwidong; Maldonado, Lizmarie; Townsend, Timothy; Reinhart, Debra R
A case study of landfill liquids addition using small diameter (5 cm) vertical wells is reported. More than 25,000 m(3) of leachate was added via 134 vertical wells installed 3 m, 12 m, and 18 m deep over five years in a landfill in Florida, US. Liquids addition performance (flow rate per unit screen length per unit liquid head) ranged from 5.6æ10(-8) to 3.6æ10(-6) m(3) s(-1) per m screen length per m liquid head. The estimated radial hydraulic conductivity ranged from 3.5æ10(-6) to 4.2æ10(-4) m s(-1). The extent of lateral moisture movement ranged from 8 to 10 m based on the responses of moisture sensors installed around vertical well clusters, and surface seeps were found to limit the achievable liquids addition rates, despite the use of concrete collars under a pressurized liquids addition scenario. The average moisture content before (51 samples) and after (272 samples) the recirculation experiments were 23% (wet weight basis) and 45% (wet weight basis), respectively, and biochemical methane potential measurements of excavated waste indicated significant (p<0.025) decomposition. PMID:25164856
Earthquake supercycle in subduction zones controlled by the width of the seismogenic zone
NASA Astrophysics Data System (ADS)
Herrend—rfer, Robert; van Dinther, Ylona; Gerya, Taras; Dalguer, Luis Angel
A supercycle describes a long-term cluster of differently-sized megathrust earthquakes, leading up to the final complete failure of a subduction zone segment. The precise controls on supercycles are unclear, although structural and frictional heterogeneities are proposed. We recognize that supercycles are suggested to occur in those regions where the estimated downdip width of the seismogenic zone is larger than average. Here we investigate the link between supercycles and the seismogenic zone downdip width using a two-dimensional numerical model. In our simulations, the first megathrust earthquakes in a supercycle generally rupture only the outermost parts of the seismogenic zone. These partial ruptures are stopped owing to a large excess of strength over stress, and transfer stresses towards the centre of the seismogenic zone. In addition to the continued tectonic loading, they thereby gradually reduce the strength excess so that the largest megathrust events finally rupture the entire seismogenic zone and release most of the accumulated stress. A greater width increases the average strength excess and thus favours supercycles over ordinary cycles of only similarly sized complete ruptures. Our results imply that larger than thus far observed earthquakes could conclude a supercycle where seismogenic zone widths are larger than average.
Controls on earthquake rupture and triggering mechanisms in subduction zones
Llenos, Andrea Lesley
Large earthquake rupture and triggering mechanisms that drive seismicity in subduction zones are investigated in this thesis using a combination of earthquake observations, statistical and physical modeling. A comparison ...