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US7552619B2 - Measurement of density and viscoelasticity with a single acoustic wave sensor - Google PatentsMeasurement of density and viscoelasticity with a single acoustic wave sensor Download PDF
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- G01N11/00—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties
- G01N11/10—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties by moving a body within the material
- G01N11/16—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties by moving a body within the material by measuring damping effect upon oscillatory body
- G01N9/00—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity
- G01N9/24—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity by observing the transmission of wave or particle radiation through the material
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/02—Indexing codes associated with the analysed material
- G01N2291/028—Material parameters
- G01N2291/02827—Elastic parameters, strength or force
This application is directed generally to the real-time measurement of liquid density using acoustic wave sensors; and more particularly to methods of distinguishing density information from viscosity information using a single sensor.
Density, also referred to as specific gravity, is an important process variable in liquid phase manufacturing processes. Density is defined as the mass of a material divided by its volume. To date, no good method of continuously monitoring the property exists. Solid state measurements of density that are suitable for in-process measurements either require multiple sensors or prior knowledge of additional material parameters (e.g. compressional elastic modulus or viscosity) or carefully controlled flow properties (e.g. in a coriolis force measurement.
Viscosity and, more generally, viscoelasticity, are properties of liquids and solids that relate the shear forces generated by or applied to a material to the amount of shear deformation or flow. While the present invention applies equally well to viscoelasticity, for the sake of clarity and simplicity, this disclosure will use viscosity as an example, with the understanding the invention extends to other viscoelastic characteristics. Viscosity is of widespread interest in many manufacturing environments and is measured as a primary quality of some products and as a secondary quality (a means of monitoring process state) in other processes. In many of these applications, measurement of density is also a requirement.
Viscosity describes the force required in order to make successive molecular layers of a liquid move past each other at a given rate of shear ("shear rate"). If one considers a liquid flowing past the walls of a container, the liquid will typically have no motion relative to the wall at the interface and will have increasingly higher velocities as one observes points successively further from the wall. The shear rate is defined as the gradient of the velocity of the liquid parallel to the surface (meters per second) with increasing distance from the surface (meters). The units of shear rate are 1/seconds. The shear stress is the amount of force per unit area that must be applied in order to cause the motion.
Hydrodynamic properties of liquids are quantified by the speed of shear sound waves in a liquid. An ideal liquid, having neither shear elasticity nor viscosity, cannot support a shear sound wave. An elastic solid having a shear stiffness, μs, can support a shear acoustic wave that propagates through the solid much as the better known compressional sound wave. The velocity of the wave is (μs/ρs)1/2, where ρs is the solid's density. Viscous liquids can support a shear sound wave; however the wave decays as it travels and is only able to travel a few wavelengths before being totally dampened out by frictional losses. The complex velocity of these waves is (jωη/ρ)1/2=(1+j)(ωη/2ρ)1/2. Measurement of the shear wave velocity thus provides information on the ratio of liquid's viscosity to its density and can thus be used to measure density if viscosity data is available.
These "sound waves" are related to the flow of liquids in confined geometries, such as capillaries, pipes and the spaces between moving parts in machinery. These flows are governed by the ratio of the intrinsic viscosity, η, to the density of the material, ρ. The ratio is known as the "kinematic viscosity", ηk=η/ρ, and has the units of area over time (m2/s).
There exist densitometers which measure changes in the resonant frequency of a tuning fork as it is filled with the test liquid. The method is highly susceptible to vibration. It is an object of the present invention to provide a sensor that is immune to most vibration levels. One method of reducing susceptibility to vibration while employing the resonant measurement method is to employ a high frequency (MHz) resonator, such that the vibrations are well outside the frequency band of the instrument.
Compressional acoustic wave devices measure the product of elastic modulus and density (acoustic impedance) or the ratio therebetween (acoustic velocity) and offer one potential avenue of obtaining both values from a single "measurement". However, the complexity of the structure and of the signal analysis has severely limited this approach for transmission based systems (acoustic spectroscopy). Typically these systems employ pulse echo systems in which a signal undergoes multiple transmissions through the test sample. The systems are extremely dependent on accurate knowledge of the path length in the sample. A preferred solution would employ a single point of contact and localized measurement.
Tuning fork methods measure the product of density and elastic modulus or the product of density and viscosity and are presently sold as densitometers. They attribute downward shifts of the resonant frequency to density (ignoring elastic modulus) and decreases in resonant quality factor (increased damping) to the viscosity-density product. The methods require prior knowledge of the elastic modulus and careful control of the depth of insertion of the tuning fork into the sample. A method is desired in which the depth of insertion is not critical and in which no other parameter need be known other than those measured by the sensor itself, or a small number of other sensors that may be coupled within a limited area or enclosure, to provide data on localized conditions.
In addition to the propagation of acoustic waves through a material, it is possible to employ acoustic waves in an adjacent solid to measure the power transfer into the viscous liquid. Power transfer from one medium to the other is governed by the ratio of the acoustic impedances of the materials. Power transfer of acoustic energy between a solid waveguide and an adjacent liquid forms the basis of several viscometers. The rate of energy transfer (power loss) is dependent on the relative acoustic impedances of the waveguide material and the adjacent liquid in a manner well-known to one skilled in the art. The acoustic impedance of the shear wave in the solid waveguide is the square root of the product of the density, ρs, and the shear elastic stiffness, μs. It is predominantly real (resistive) and is analogous to a nearly-lossless transmission line's characteristic impedance in electromagnetics. The acoustic impedance of a shear wave in a viscous liquid is the square root of the product of the stiffness term, jωη, with the density, ρ. The characteristic impedance of the viscous liquid is typically very small compared to the elastic solid, resulting in a low power transfer. At low viscosity the power transfer is proportional to (ωρη)1/2. Therefore, if the viscosity is known, density can be measured.
U.S. Pat. No. 5,708,191 Greenwood et al., U.S. Pat. No. 5,886,250 Greenwood et al., U.S. Pat. Nos. 6,082,180 and 6,082,181 to Greenwood, present a family of densitometer sensor designs that employ input and output transducers to measure changes in reflected signal strength of acoustic waves as they reflect near a critical angle of incidence. These viscometers measure either viscosity-density product or elasticity-density product based on the reflection of acoustic waves from the liquid-loaded face of a solid material supporting the transducers. The sensors measure reflection coefficients of the wave from solid-liquid boundaries upon a few reflection events of a pulsed or continuous-wave signal. Such methods offer less sensitivity and resolution of the measured quantity than do resonant and multi-reflective devices. The latter enjoy higher sensitivity from the continuous interaction of their acoustic waves with the solid-liquid interface. The discrete-reflection methods do not enjoy the simplicity of manufacture or operation of a continuous acoustic wave interaction surface, nor do they provide similar sensitivity or resolution. Finally, the discrete reflection methods assume a fixed elastic modulus (for the more common compressional wave version) or viscosity (for the less common shear wave version) in order to extract density information from the measured response of the sensor.
Another method of performing the density-viscosity product measurement is to immerse a resonator manufactured on a piezoelectric substrate and supporting a transverse shear mode of resonance, typically a disc of quartz crystal of AT cut, into the liquid and to measure the shift in resonant frequency or the loss of power at resonance. This method has been plagued by poor reproducibility when used with affordable instrumentation, primarily due to the lack of a differential measurement within the sensor.
This issue has been overcome through the use of two-port devices based on multi-pole resonators using shear wave acoustic modes, such as the SH-SAW (Shear Horizontal-Surface Acoustical Wave), SHAPM (Shear Horizontal Acoustical Plate Mode), MPS (Monolithic Piezoelectric Sensor) e.g. as described in U.S. Pat. No. 6,033,852, issued Mar. 7, 2000 to Andle et al.
U.S. Pat. Nos. 5,741,961 and 5,798,452 to Martin et al. disclosed a method in which two acoustic wave sensors having different surface treatment exhibit essentially identical responses to viscosity-density product but differing responses to the density. A reference sensor provides data on the product of viscosity and density and employs a smooth surface. The second sensor has an intentionally roughened surface, typically having grooves or pits in its surface for trapping a certain volume of fluid. The added mass creates a finite frequency shift with little or no power loss in addition to the power loss and frequency shift of the viscously entrained liquid. The difference in the frequency shifts between the two sensors is therefore attributed to the mass of the material trapped in grooves or wells of a textured surface, providing a measure proportional to the density via the frequency difference. The density-viscosity product is available via the common-mode frequency shift. While this method is attractive, it incurs difficulties in sensor-to-sensor reproducibility when the two sensors are manufactured on different substrates.
The addition of such grooves to one of a pair of shear horizontal surface acoustic wave (SH-SAW, also known as Love Wave, surface transverse wave, and the like.) sensors is also disclosed (Herrmann et al., U.S. Pat. No. 6,543,274), and the extension of this approach to SHAPM sensors is contemplated herein. This method offers higher frequency, smaller size, and improved sensitivity at the expense of manufacturing complexity and available dynamic range. However Herrmann still finds the use of two completely identical sensor elements necessary for measuring both parameters, and therefore it does not overcome the sensor-to-sensor limitations of the Martin device.
In a U.S. Pat. No. 7,007,546 to Andle titled "Measurement, Compensation and Control of Equivalent Shear Rate in Acoustic Wave Sensors" (which is incorporated herein by reference in its entirety), the inventor of the present application disclosed a method for measuring viscosity and shear rate at which the measurement is performed by utilizing an acoustic wave sensor, and calculating the shear rate as a function of the characteristic rate of fluid movement in response to a given power transmitted to a fluid, and the viscosity of the fluid. The acoustic wave device has a characteristic relationship between input power, output power, and an acoustic wave amplitude at a selected region between the input and output transducer. The acoustic wave device is coupled to the measured fluid. A predetermined power level Pin of a harmonic signal is applied to an input transducer, to impart an acoustic wave at the selected region. Output power level Pout is measured at the output transducer. Using the characteristic relationship, and the input and output power levels, the amplitude of the average acoustic wave imparted to the fluid is calculated. Measuring the viscosity of the fluid to obtain a measured viscosity at the selected region, allows calculating of the shear rate of the fluid at the selected region, by using the frequency, the viscosity measurement, and the acoustic wave amplitude. This invention may be beneficially used with the present invention as explained below.
There is therefore a clear and unanswered need for a densitometer, and also for a combination densitometer/viscosity meter, that is reliable, precise, easy to manufacture, and easy to install in various applications, which does not rely necessarily on the use of a plurality of sensors and that is compensated for wide variations in the viscosity of the sample. The preferred embodiments of the present invention provide such solutions.
It is an object of the present invention to replace the separate textured sensor and smooth reference one port (impedance element) devices with a single two-port (transmission) device while continuing to provide the ability to measure density and viscosity with the device. It is an optional object of the present invention to accomplish the measurement of density in a viscous liquid in a manner that is compatible with previously disclosed measurement and control of the shear rate at which the liquid's viscosity is measured. Other objects of the invention will be clear to the skilled in the art from the description, claims, and drawings of the present application.
The preferred embodiment of the present invention utilizes a device, namely a two-port, two-pole coupled resonator with a textured entrapment layer in contact with a fluid to be measured, such as a liquid or a gas. It further discloses preferred electronic circuits including said device, that enable the user to employ one or more disclosed methods of estimating the density of a viscous liquid, independently or simultaneous with the measurement of viscosity. The preferred embodiment further provides the capacity to measure, and/or control, the shear rate at which the viscosity measurement is conducted.
Optionally, the present invention further allows measuring and controlling the shear rate at which the viscosity is measured, in combination with measuring the density. This offers the distinct advantage of allowing the error due to shear rate dependence of viscosity to be averaged out of the density measurement for complete viscosity compensation of the measured density. It further allows a single sensor to provide data on acoustic viscosity (ρη), intrinsic viscosity (η) and/or kinematic viscosity (η/ρ) as a function of shear rate, implementing a compact, solid state rheometer for materials characterization and evaluation.
Therefore in an aspect of the present invention there is provided a method for measuring fluid density comprising the steps of providing a sensor, feeding an input electrical signal to the sensor input resonator, and measuring the density of the fluid. The sensor comprises a liquid phase acoustic wave device (LPAWD) having an entrapment layer coupled thereto. The entrapment layer has a textured surface in contact with the fluid, and having a known volume available for entrapping said fluid; the LPAWD has an input and an output transducers electromechanically coupled respectively to a first and second resonators. The resonators being sufficiently coupled therebetween to provide the LPAWD with an electrical transfer function characterized by at least a first resonant frequency FS and a second resonant frequency FA at or about 180 phase shift relative to said Fs. Preferably, the step of measuring the density further comprises the steps of measuring the second resonant frequency FA; and using the measured resonant frequency, and characteristic response of said LPAWD, to calculate the density of the fluid. The step of measuring further comprises the step of using a calibration function to account for an approximated viscosity of said fluid. Further preferably, the method comprises the steps of providing an amplifier coupled between said input and output transducers, the amplifier having a gain sufficiently high to cause signals therethrough to oscillate at or about FA; and providing a frequency sensing circuit to sense changes in the frequency of oscillations.
In another aspect of the invention, there is provided a method of measuring density and viscosity of a fluid. The method comprising the steps of:
- Providing a sensor comprising a liquid phase acoustic wave device (LPAWD) having an entrapment layer coupled thereto or embedded therein, the entrapment layer having a textured surface for contact with the fluid, and having a known volume available for entrapping said fluid. The LPAWD comprises an input and an output transducers electromechanically coupled to a first and second resonators respectively. The resonators are sufficiently coupled therebetween to provide the LPAWD with an electrical transfer function characterized by a first resonant frequency FS, and a second resonant frequency FA at or about 180 phase shift relative to said Fs. An input electrical signal is fed to the input transducer, and the density and viscosity of the fluid are measured. The method preferably comprises the steps of measuring the power difference between the input and output transducers, to obtain a product of the viscosity and density of said fluid, which can then be used in the step of measuring the viscosity. Preferably the step of measuring the density comprises measuring the frequency, FA. The measured density can be used to compensate for density effects on the viscosity measurements, and the measured viscosity can be used to compensate for viscosity effects in measuring the density.
Optionally, the input electrical signal is controlled to produce a predetermined shear rate under which said viscosity is being measured. Further optionally, the shear rate is controlled by controlling the input electrical signal at an energy level, PIN, to produce a desired displacement of said entrapment layer.
The energy level, PIN, is calculated using the formulae: {dot over (γ)}=ωU/δ, where ω=2πFA,
is the penetration depth of the wave into a fluid having viscosity, η, and density, ρ, and the acoustic wave amplitude U=C√{square root over (Pavg)} is determined by a device constant, C, and an energy level, Pavg, being a geometric mean of power levels measured at said input PIN and output transducers.
In the preferred embodiment of the invention, the step of measuring the density comprises measuring the said second resonant frequency, and the step of measuring the viscosity comprises measuring power insertion loss between said input resonator and output resonator. However in another embodiment, the step of measuring the viscosity comprises measuring the shift of one or both of said resonant frequencies. The preferred embodiment also comprises the step of controlling the energy level of the input electrical signal so as to control the shear rate in which the viscosity is measured.
In another aspect of the invention there is provided a sensor for measuring viscosity and/or density of a fluid, the sensor comprises a substrate having an input and an output transducer, coupled respectively to a first and a second resonator. The resonators are sufficiently closely coupled therebetween, to form a device with an electrical transfer function characterized by at least a first resonant frequency FS, and a second resonant frequency FA at or about 180 phase shift relative to said frequency Fs. The sensor has an entrapment layer coupled to the substrate, or embedded therein. The entrapment layer is coupled to said substrate directly or by an intermediate layer. Preferably, the entrapment layer comprises at least one face having a groove or grooves formed therein (i.e. the grooves may be in the entrapment layer or deposited on it.), for trapping a known volume of the fluid. The grooves are preferably oriented perpendicular to the direction of wave motion in said substrate, and preferably dimensioned to be smaller than the length of a quarter of the wavelengths in the liquid, of said resonant frequency FS. Such grooves may be formed by depositing material on said face to form ridges, the grooves being defined between said ridges. Alternatively, the grooves may be cut (e.g. by drilling, etching, and the like) into the substrate. As one of many alternatives to the grooves, the entrapment layer may comprise at least one chamber formed therein, the chamber having at least one opening for entrapping a known volume of said fluid. The chamber may be cut into the entrapment layer or formed by material deposited thereupon. Most preferably, the entrapment layer is integral to at least one face of the substrate. Also preferably, the entrapment layer covers an approximately equal area of each of said resonators, and at least 50% of the frontal area of each resonator. Most preferably, the textured area covers the whole surface area of at least one face of the entrapment layer. Such a sensor may be used for density measurements alone by measuring the resonant frequency FA.
In yet another aspect of the invention there is provided an apparatus for measuring density and viscosity of a fluid, the apparatus comprising a sensor comprising a substrate having an input and an output transducers coupled respectively to a first and a second resonators; said first and second resonators being sufficiently closely coupled therebetween to form an electrical transfer function characterized by at least a first resonant frequency FS, and a second resonant frequency FA, at or about 180 degrees phase shift to said frequency FS, and an entrapment layer coupled to said substrate, or embedded therein. The system further comprises a first measuring means for measuring the density of said fluid, and a second measuring means for measuring a product of said viscosity and density. Such sensor may be used for density measurements alone by measuring the resonant frequency FA, in which case the second measuring means is not required. The apparatus preferably further comprises a computer adapted for computing the density from the measured product and the measured density. Such computer may be a special purpose computer, or a general purpose computer. Software in the computer may be easily adapted to perform the needed steps. The first measuring means preferably comprises frequency measurement equipment. By way of a non limiting example, the first measuring means can comprise a first oscillator coupled between the input and resonator, constructed to oscillate at 180° phase relative to an input electrical energy inputted to said input transducer, and preferably also a second oscillator coupled between said output and input resonator and constructed to oscillate at or about 0° phase from said input electrical energy. Preferably, the second measuring means comprises circuitry to measure insertion power loss between said input and output transducers. Alternatively, the second measuring means comprises circuitry to measure difference frequencies between said first and second oscillators.
In the most preferable embodiment, the apparatus controls the input energy in order to measure the viscosity at varying shear rate. Optionally, a temperature sensor is further included in the apparatus.
The invention will be better understood in light of the attached drawings, in which:
It is an important object of the present invention to provide a method of obtaining the measurements of density and of density-viscosity product, in a single sensor with essentially simultaneous measurement. The aspects of the invention are equally applicable to any shear horizontal (SH) acoustic wave device used to implement the sensor, whether it employs the bulk acoustic wave (BAW) parallel plate resonator, SH acoustic plate mode (SHAPM) parallel plate waveguide, or the SH surface acoustic wave (SH-SAW) planar device structure (commonly known as a Love wave device).
The invention is equally applicable to any acoustic wave device not having SH wave displacements but still having acoustic wave amplitudes confined primarily to the surface plane of the acoustic wave device prior to texturing. It is further applicable to flexural plate wave (FPW) devices employing the slow mode of a thin membrane using either piezoelectric, magnetic, or any other convenient method of acoustic wave transduction. In general, the present invention may be practiced on any acoustic wave device having a combination of wave displacement polarizations and or wave velocity such as to control energy loss caused by contact with a liquid and viscous coupling of energy into said liquid. Generically such a sensor shall be referred to as a liquid phase acoustic wave device (LPAWD). The invention relates to the use of a multi-pole, coupled-resonator filter structure using said LPAWD, with the preferred embodiment having two poles.
An important aspect of the invention is based on a liquid phase acoustic wave device having a substrate and at least two transducers that provide electrical input and output ports. The two transducers are sufficiently tightly coupled to a first and a second resonant structure, said resonant structures coupled to each other, either directly or via additional resonant or transmission structures, so as to exhibit electrical transfer function similar to a resonator filter having at least a dual pole transfer function between the input and the output. The principles of such Two Pole Coupled Resonator Filter structure are explained in more detail in an article by M. G. Schweyer, J. A. Hilton, J. E. Munson, J. C. Andle, J. M. Hammond, and R. M. Lec, titled "A Novel Monolithic Piezoelectric Sensor", published in the 1997 IEEE International Frequency Control Symposium, pp. 32-40 or in an article by M. B. King, L. W. Heep and J. C. Andle, titled "1500 MHz Coupled Resonator Filter", and published in the Proceedings of the 1987 IEEE Ultrasonics Symposium, pp. 127-130.
Such two-pole resonators may be modeled and/or designed based on a structure consisting of two simple resonator structures, one coupled to an input transducer connected between the input connection and ground and the other coupled to an output transducer connected between the output connection and ground, with a coupling mechanism between said resonators. In the preferred embodiment of the present invention, the resonators are acoustic structures of either mirrored plate or grating reflector types, and the coupling to the electrical input and output is accomplished via an appropriate piezoelectric or similar transducer structure. Clearly, other methods of creating such multi-pole-multi-port structures exist, and similarly connection methods may vary as known, e.g. by providing separate floating input and output circuits without a common 'ground'. Magnetostrictive, electrostrictive, piezoresistive and other transduction means are equally viable and shall be inclusively considered as coupling a resonator to an electrical terminal or terminals.
The structure functions by providing a transfer of energy between one resonator and the other due to the coupling mechanism. The result of the coupling is to create a combined device in which there are at least two resonant modes, each being a superposition of the wave envelope supported by the individual resonators. One such combined resonance FS, having the lower frequency and typically 180° of phase shift, has a symmetric superposition, while the other combined resonance FA, having the higher frequency and typically 0° of phase shift, has an antisymmetric superposition. It is not necessary that the two coupled resonators be identical. It is important to note that in order to achieve a two-pole coupled resonator it is insufficient to merely place two independent resonators on a single substrate, but sufficiently close coupling between the resonators is required, to provide the wave interaction described above. The degree of coupling, M, is such that M=ΔF/F0=2(FA−FS)/(FA+FS), results in a quantifiable difference between FA and FS. One skilled in the art will recognize that the absolute phase shifts of the signal at the two resonances can be altered from the typical values by internal and external influences, including by way of non-limiting example, altering the connection polarity, variations in transducer capacitance, and the use of external phase shifting circuitry. Where the values 180° and 0° are used throughout this document, it should be taken to mean either the actual phase of the signal transmission at FS or FA or the phase shift required of an amplifier to oscillate at FS or FA, as appropriate from the context, and not the specific numerical value, 180° or 0°.
The general shape of such a two-pole frequency transfer function is represented schematically in
Therefore a preferred embodiment of the invention, depicted schematically in part in
The transducers in the preferred embodiments use piezoelectric coupling on a substrate consisting of one or more layers of material, at least one of which is piezoelectric. The most preferable embodiment is an inter-digitated transducer. Alternative embodiments allow for electrical coupling to the mechanical resonators embedded in the substrate using magnetic, electrostrictive, piezoresistive, optical or other equivalent transduction means to convert input electrical signals into mechanical energy trapped within the coupled resonators and to detect said trapped signals and such alternate means of electrically exciting and measuring the acoustic energy in the coupled resonators should be considered within the scope of the present invention.
The input and output resonators, are also coupled to each other via the substrate and are mutually coupled, i.e. the perturbation originating in the input resonator reach the output resonator, and vice versa, so as to provide the desired two pole frequency transfer function. In order to achieve such close coupling the distance between the input and output resonator could be calculated or approximated by methods specific to the particular resonator geometry and widely published in the literature. In general, the calculation involves first estimating the extent of the evanescent or fringing mechanical fields outside one resonator and in the direction of the other resonator, then evaluating the overlap of the fringing fields of one resonator with those of the other resonator, said degree of interaction representing the coupling factor between said resonators. The preferred method of calculation is to treat the structure in cross section as a multi-region, one dimensional waveguide with boundary conditions between said regions of continuity of mechanical amplitude and continuity of mechanical stress. Such boundary value analysis yields coupled differential equations that may be solved for the symmetric and antisymmetric modes of the coupled structure and the associated frequencies. This method of calculating is but one of many known to the skilled in the art, and any convenient method may be used. While the preferred embodiment employs rectangular geometries for manufacturing and analytical simplicity, circular, semicircular, elliptical, hyperbolic, parabolic and other resonator shapes that are equally applicable are known, and in some applications preferred. Similarly, while the preferred embodiment employs polished, parallel surfaces of the piezoelectric substrate, there are in the literature both spherically and aspherically contoured resonator structures that are preferable in select applications to better trap the acoustic energy albeit at the cost of increased manufacturing complexity.
It has been experimentally observed that the two (or more) poles (i.e. resonant frequencies) move in unison, with essentially constant difference frequency, under lossless mass loading, as shown in
The invention employs an entrapment layer 420, preferably equally disposed over the first and second resonators and, more preferably, uniformly disposed over the entire sensing surface, to entrap a known volume of viscous liquid and enforce substantially rigid motion upon it via the textured surface of the entrapment layer. The effect of this rigidly entrapped liquid is to incur a corresponding downward frequency shift of the entire electrical response due to the mass loading phenomena, without altering the relative differences between the first and second resonant frequencies in the electrical response. The entrapment layer entraps a known volume of the measured fluid to the crystal, in a manner that will cause the fluid to behave as if it was rigidly attached to the crystal. Knowledge of the mass sensitivity coefficient of frequency, Sm, the entrained volume, V, the sensor area, A, and the downward frequency shift from an unloaded state, ΔF, is sufficient to allow density to be estimated as
ρ=ΔF*A/V*S m
The mass sensitivity coefficient may be estimated from perturbation theory using formulae that are specific to the given resonator structure and well known to one skilled in the art. This formula is directly analogous to the well known quartz crystal deposition monitor for solid films. This simplistic estimation ignores the role of viscosity as a source of error and assumes a suitable definition of the frequency of the electrical response. In the preferred embodiment of a two-pole, coupled resonator filter, the value of ΔF is the change of FA, which has been experimentally observed to have minimal sensitivity to viscous loading, SV.
In the preferred embodiment the entrapment layer is implemented by providing grooves 425 in a metal film deposited on one surface of a piezoelectric crystal that is brought in contact with a fluid to be measured, as shown in
It should be noted that an entrapment layer need not necessarily be provided on the crystal face itself, but that an intermediate layer or layers may also be provided between the crystal and the fluid entrapment layer. Furthermore, the entrapment may occur by cutting, etching, drilling or depositing material, on the crystal face or on the intermediate layer.
As there are numerous methods of creating an entrapment layer, these specifications will relate to an entrapment layer as any layer being coupled to the acoustic wave device, or being integrated therein, having voids therein for entrapping a known volume of the measured fluid, in such a way that the entrapment layer causes a change in the resonant characteristics of the acoustic wave device due to the mass of the fluid trapped in the voids
Prior experimental data in a smooth sensor, i.e. a sensor without an entrapment layer, shows that viscoelastic loading causes minimal (if any) frequency shift of the anti-symmetric resonance frequency, FA, and substantial downward shift of the symmetric resonance frequency FS. This indicates that FA is substantially compensated, by the inherent physics of the device, against viscosity variations. Data also has shown that simple mass loading, as would occur due to fluid entrapped in the entrapment layer, imparts equal frequency shifts to both resonant frequencies. While the nearly complete orthogonality between density and viscosity observed in the experimental data for FA may not occur for all designs, the effects of viscosity and density are mathematically separable in all cases and can be naturally separated by design in many cases.
Therefore, an aspect of the invention contemplates a densitometer using only the FA resonant frequency of a two-pole, coupled-resonator sensor having an entrapment layer. Such a densitometer would need to be calibrated for any residual dependence on viscosity in a given process to be highly accurate, but will provide a viable process monitoring method for relatively low precision applications merely using the natural orthogonality.
A densitometer as describe above would comprise an acoustic wave device with a coupled entrapment layer that is in contact with the measured fluid. As described above, the frequency characteristics change as a result of the trapped mass is represented as a frequency shift of both resonant frequencies FS and FA.
The preferred simplest densitometer circuit contemplated in these specifications uses a subset of the block diagram of
In order to measure the viscosity as well as the density, the resonant frequency FS is tracked by employing the sensor element 510 as the feedback element of a 180° amplifier 530, and a frequency sensing circuitry such as frequency counter 535. While not shown, the skilled in the art will realize that different circuitry is equivalently applicable for sensing the common mode frequency shift, such as frequency mixing, and the like. Using the methods of patent application Ser. No. 10/743,986 described above, the viscosity and shear rate may be measured using the sum and difference of power levels PINA and POUTA, or PINS and POUTS respectively.
As seen in
It is also possible to measure the viscosity-density product of the liquid by measuring the power loss between the input and output transducers while simultaneously measuring the density via the frequency shift of the FA resonant frequency. Such a sensor could self-calibrate for the residual effects of viscosity on the density measurement and could provide data on acoustic viscosity (ρη), intrinsic viscosity (η), or kinematic viscosity (η/ρ) as well as being a direct measurement of density.
If the orthogonality of viscosity and density effects on FA are insufficient, viscosity may be calculated, 650 using power level measurements, POUTA and PINA, or obtained from an external source. This data may then be used with predetermined calibration data to correct the density value. The corrected density is calculated as ρCORR=A*H(η)*(FA′−FA)/(SM*V), where H(η) is a calibration function previously determined.
Data about the fluid viscosity 650 is estimated as above or obtained from an external source. The viscosity data is used to select an appropriate calibration table for the sensor acting at the assumed viscosity 650, and the table is used to compute the fluid density using the frequency shift obtained at step 635 and the appropriate table. Clearly, while all calculation steps may be made by hand, a computerized solution is preferable, and will be clear to those skilled in the art. Specialized circuitry that does not require specific software may also be utilized. It should also be noted that the viscosity effect may in some cases be minimal, and therefore the steps of selecting an appropriate calibration table may not be necessary. Naturally, the invention extends to such embodiment as well.
It is possible to simultaneously measure both the viscosity and the density by measuring both the symmetric and anti-symmetric resonant frequencies; wherein the difference between the frequencies is primarily dependent on viscosity-density product and the frequency of the second resonant frequency FA is primarily dependent on the density.
Note that while the density may be obtained by measurement of the antisymmetric frequency alone, the measurement is expected to provide better accuracy when compensated using viscosity information from the changes in ΔF=FA−FS. Both resonant frequencies are measured in a reference medium, typically air, and in the liquid. The antisymmetric resonant frequency FA is measured as disclosed above. A second amplifier having 180 degree phase shift 530, is also connected between the input and output of the sensor element, 510. This second oscillator loop generates a signal with frequency, FS, which is counted by frequency counter, 535. Switching elements control the two oscillators. Optionally the switching elements are replaced or complemented by other means of isolating the two feedback paths, such as cross-over networks. As connecting opposite phase amplifiers together may cause shorting of the amplifiers, cross talk problems, and the like, it is important to isolate the amplifiers. Many known examples exist, such as switching power to the amplifiers alternately, or switching the amplifier output as needed. In the preferred embodiment, CPU 555 controls the amplifiers' operation.
The change in the difference between the two frequencies between operation in air (FA−FS) and in the liquid, (FA′−FS′), is related to the product of density and viscosity while the change in FA is dependent on density. The nonlinear system of two equations in two unknowns is solved using standard numerical methods using a computer. While measuring FA is preferred by virtue of its minimal dependence on viscosity, any frequency point on the electrical response may be tracked and compensated for the viscosity-induced shifts of the measured frequency and that measuring phase changes at a constant frequency near the "measured frequency" is equivalent to measuring changes in that frequency.
Two amplifiers, a first having zero phase, 730, and a second having 180 degrees of phase shift of an electrical signal amplified therein, 740, are coupled between the input 735 and output 745 transducers. The amplifiers are connected through suitable switching circuits 750. At FS, the LPAWD coupled resonator filter provides a transmission phase of typically 180° while at anti-symmetric frequency FA it provides typically 0° transmission phase shift. Amplifier 740 will oscillate on Fs and amplifier 730 will oscillate on. FA. Supporting coupling/decoupling, gain setting, and other common components needed for the operation of the amplifiers as oscillators are well known and not discussed herein. While frequency counters, 760 and 765, are proposed, alternate means including frequency to voltage converters or the use of mixers to obtain difference frequencies and sum frequencies are equally applicable and contemplated herein, but as those are well known techniques, are not detailed or shown.
In these specifications, elasticity and viscosity are the real and imaginary parts of the complex viscoelastic modulus, μ+jωη. It is widely desired in materials analysis to characterize the viscoelastic properties as a function of shear rate and temperature without errors due to inadequate knowledge of the associated density.
It should be noted that non-Newtonian liquids would yield differing viscosity estimates based on frequency data and on power loss data. The viscoelastic effect is unequal on these terms in a non-Newtonian (e.g. Maxwellian) fluid. The inventor therefore further contemplates measuring density, viscosity, effective shear elasticity, and shear rate simultaneously by employing both ΔF and power loss data to obtain both the real (elasticity) and imaginary (viscosity) components of viscoelasticity while using FAVE and average power to obtain the density and shear rate data. Using the methods of U.S. patent application Ser. No. 10/743,986 described above, it is possible further to perform this calculation over a range of shear rates. Since density is independent of shear rate, it is possible to eliminate errors in the separation of density and viscoelasticity that may occur due to measurement errors associated with non-Newtonian viscosity. Such schemes and algorithms would be considered equivalent by one skilled in the art.
Therefore in the most preferred embodiment of the invention is a device and methods for the independent measurement of density, the simultaneous measurement of density and viscosity, and/or the simultaneous measurements of density and complex viscoelasticity of a sample at a known shear rate. The device utilizes a coupled-resonator filter in contact with the sampled liquid via an entrapment layer. The resonator filter has two or more mutually coupled resonant cavities, at least one of which is coupled to an input transducer and at least one of which is coupled to an output transducer, and therefore provides at least a two pole electrical transfer function from the input terminal to the output terminal. The device may be succinctly described as a two-port (separate inputs and outputs), multi-pole (multiple separate resonant frequencies), textured-surfaced, coupled-resonator filter. The method for using the device involves coupling the entrapment layer to the fluid to be measured, exciting the device by an alternating electrical energy provided to the input transducer. Measuring the power insertion loss, i.e. the difference between the power inputted to the input transducer and the power at the output of the output transducer, provides a measure of the intrinsic viscosity of the fluid times its density (ηρ). Controlling the input power level provides a mechanism for controlling the shear rate at which the viscosity measurement is preformed. Measuring the frequency shift by measuring a first resonant frequency FS and a second resonant frequency FA as described above. The frequency shift of FA is primarily attributed to the mass loading due to the entrapped fluid, while the frequency shift and/or amplitude change of both resonant frequencies FS and FA provide data from which the viscosity-density product is derived. As the viscosity is known from either the insertion loss or difference frequency measurement steps above, and the volume of the fluid trapped in the entrapment layer is known from the entrapment layer geometry, deriving the density of the fluid from the data is a matter of mathematical manipulation well known in the art. Most preferably an independent temperature measurement is also taken to relate the measured/calculated parameters to specific temperature.
The fields in which the invention may be practiced are widely varied. By way of a non limiting example, the invention may be used to measure viscosity and density in situ within a manufacturing process such as quality of slurry in paper making or casting operations, ink in printing processes, plastic material in casting or injection operations, biological and chemical medical processing, distillation processes such as oil refinery, and the like. The invention may similarly be used to monitor fluid characteristics of operational fluids such as oil and fuel in engines, turbines and other machinery, during machine operation or by sampling. Furthermore, the invention may be used in material analysis utilizing small samples, to aid in identifying the material composition. Clearly the invention will be beneficial for analyzing liquid, semi-liquid, and in some cases gaseous end products such as milk, oil, acetylene and other heavy gasses, pre-made slurry, concrete, fuel oils, and the like. Other uses will be clear to those skilled in their respective arts in which a compact, robust and accurate measurement of density and viscosity are of value.
It will be clear to those skilled in the art that the physical structures, the calculations, process flow, and other details provided above are but examples of how to make and/or use the various aspects of the invention, and that one skilled in the art would be able to provide numerous changes to the order of steps, the structure, software, and the electronic circuitry described above, given the flexible nature of electronics and software. While there has been provided a complete description of what is at present believed to be the best methods to practice the invention, the invention is clearly directed at covering such modifications and equivalents as will be clear to those skilled persons, and not limited to the logical block arrangement, algorithms, electronic circuitry, physical aspects, or other aspects of the description and drawings provided by way of non-limiting example only.
Claims (17)
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|Measurements of density and viscoelasticity with a single acoustic wave sensor
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|Measurement of density and viscoelasticity with a single acoustic wave sensor
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|WO2005114138A8 (en)
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|Publication date
|US20070144240A1 (en)
|WO2005114138A8 (en)
|WO2005114138A3 (en)
|DE112004002772T5 (en)
|WO2005114138A2 (en)
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Black Friday and Cyber Monday are behind us, but the relentless commercial onslaught that is Christmas is not done with us yet — not by a long shot. To borrow what Matt Taibbi vividly wrote about Goldman Sachs, the commercial Christmas machine will continue to wrap itself around the face of Western humanity for the next 30 days like a great vampire squid, "relentlessly jamming its blood funnel into anything that smells like money." As you'll see, even some metal bands turn into vampire squids this time of year.
Yes, we need to vent a bit. That's all. To be brutally honest, which is the only kind of honest we know how to be at NCS, we have nothing original to say about Christmas. Will that stop us from expressing our opinions? Fuck no! If incisive original thought were a requirement for NCS posts, we'd be in very deep shit. Lacking any such constraints, however, we will proceed — and you can't stop us!
You might infer from the title of this post that it will just be an atheistic diatribe against Christianity, but you would be wrong. From our point of view, it really doesn't matter whether you're a Christian, an adherent of some other faith, or someone who has concluded that God is a myth, that Jesus was just a man, and that religion is for feeble-minded sheep.
Really, it doesn't matter what you believe or don't believe: All right-thinking people, Christians or not, theists or atheists, should raise their voices and middle fingers in unison and repeat after us: FUCK CHRISTMAS! (more after the jump . . .)
[EDITOR'S NOTE: Today we have another contribution from our Midwestern correspondent BadWolf — this time, an awesome interview with Grace Perry and Matt Martinez following a recent live performance . . .]
The following interview with Arizona Death Metal masterminds Landmine Marathon was conducted on November 20, 2010 at Frankie's Inner City in Toledo, Ohio by BadWolf.
Landmine Marathon killed it that evening, by the way.
G– My name is Grace Perry and I'm the singer for Landmine Marathon.
M– My name is Matt Martinez and I play bass.
BW– You guys, the whole tour [Skeletonwitch, Landmine Marathon, Withered (who did not play on this date)] is on Prosthetic Records. What is your relationship with Prosthetic Records?
G– A really great relationship. We've only been with them for a year now I think. We released Sovereign Descent with them, and they re-released Rusted Eyes Awake as well as Wounded. It's a very easygoing relationship—not very demanding. I'm happy.
M– The really cool thing is that their roster isn't huge. It isn't ten releases a month; they really focus on their bands. That's been the awesome thing. (more after the jump .. including a video)
You probably thought we were finished with our mini-series on long songs — but no, we're not finished. We have one more. Well, maybe two more, if we ever get around to the second one in between reviewing the flood of stunning new albums that were released the last couple of weeks. But at least one more, today.
In our previous installments of this series, we reviewed long songs by Hull, Agalloch, Akelei, and Radiance. Today, we're writing about the longest song yet in this series: It's an album-length song released last year by a black-metal band called Obitus. The album is divided into seven tracks, but that's merely to facilitate jumping to favorite passages; Obitus intended the album to be heard as a single, seamless work, more than 47 minutes in length.
Now, in today's frenetically-paced, attention-deficit-afflicted world, asking music fans to sit still for an entire album's worth of non-stop listening is like trying to stop a surging river in its course with kind words. But in our heart-of-hearts, we know that unless we slow down and focus, at least every now and then, we will miss out on some valuable experiences. And so it is with the second full-length album from Obitus — The March of the Drones.
Obitus was formed in May 2000 by a couple of Swedes, Anders Ahlbäck (who plays all the instruments) and Johan Huldtgren (vocals and lyrics). Since then, they've produced a demo, a split, an EP, a debut full-length that was never released, and The March of the Drones. They took some risks creating an album-length song, testing the patience of a mostly impatient population of metalhead fans. But they clearly poured their hearts and souls into this work — and don't be misled by the title: It refers to the album's lyrical themes. Musically, The March of the Drones is a full-body immersion into a surging torrent of dark fire. (more after the jump . . . including a sample of the music)
It's been almost three weeks since I put up a MISCELLANY post, which is way too long. My vacation had something to do with that delay, but still — too long. My list of bands to check out has grown to gargantuan proportions, which means the selection for today is even more random than usual — and this post is also really long. But it's a fucking holiday weekend, and what else have you got to do?
You know the rules of this game by now: I keep a running list of bands I've never heard but who look interesting for one reason or another, and when I have time, I randomly pick a few names off the list and listen to one song from each band — not knowing in advance whether the music will be worth a damn. And then I record impressions in these MISCELLANY blogs, and provide you the songs I heard so you can form your own opinions.
For today's way-late installment, I checked out four bands from distant countries. In fact, distance was sort of the criterion I used for picking names off the list this time. Of course, all countries are distant from Seattle, except Canada, which is more or less spitting distance away.
Not that I would ever spit on Canada. In fact, when I get nauseous about the state of political discourse in the U.S. (which happens about every other day), I fantasize about moving to Canada — until it dawns on me that I don't know anything about the state of Canadian political discourse, plus the national sport seems to be hockey, which always looks to me like someone dropped a big pile of ants onto a piece of ice and stirred 'em into a state of frothing anger with a big stick. In other words, I have no fucking idea what's happening.
Where was I? Oh yeah — metal bands from distant countries. For today's post I checked out Heathen Beast (India), Skrypt (India), Bilocate (Jordan), and (in a late addition to the post) Ektomorf (Hungary). See what I found (and listen to the songs), after the jump. And just to spare you the suspense — I was pretty well blown away by what I heard from the first three bands, and the fourth was at least fun.
Legend is a metalcore band from Michigan whose debut album, Valediction, we reviewed in June (here). At that time, the members of Legend included vocalist Chad Ruhlig (ex-For the Fallen Dreams), bass-player Joe Ellis (also ex-FTFD), and guitarist Aaron "Bubble" Patrick (ex-Bury Your Dead). In the space of the last five months, the line-up has undergone a thorough revision. Ruhlig is still on vocals (thankfully), but Ellis and Patrick are gone, and the new line-up consists of Devan Dickerson (guitar), Matty Harrah (bass and vocals), and Dylan Shippey (drums).
Today's update was prompted by the revised Legend's hot-off-the-presses release of a new song called "Proven". It's a hot song — heavy as fuck, obliterating as a jackhammer with a mind of its own, synaptically convulsing, and fueled by Chad Ruhlig's wonderful hardcore howls and death-metal growls. The production has got just the right mix of muddiness and clarity for a brutally downtuned song like this. And to put some sweet icing on this dense cake, Legend's label (Rise Records) is making the song available for free download at the band's Pure Volume site (here). We don't know how long the free download will last, so don't delay — go get it.
Now, even though it only takes seconds to download this song, you may still want to hear it before allowing it to occupy the precious storage on your hard drive. We can handle that. We can let you hear the song first. And we can even do better than that. We can play you the song while at the same time allowing you to see a time-lapse video of Josh Schroeder, a.k.a. "Metal Josh," creating new merch artwork for Legend. Josh also runs a professional recording studio (called Random Awesome), and he happens to be the dude who recorded this Legend single (in addition to recording albums for Dagon, For Today, Beneath the Sky, Hester Prynne and many others). Multi-talented people make us insecure.
So, while creating the artwork that you see above, Josh kept the camera rolling and then speeded it up so you can see the creation of the art from beginning to end while you listen to the song. Seriously, it's so much fun to watch. So, continue past the jump and watch it!
[EDITOR'S NOTE: Our UK contributor Andy Synn made his way to Oslo, Norway, to catch Dark Tranquillity's live show on November 6. DT was supported at that club show by fellow Swedish metallers Avatar and Marionette. Andy provides this review of the night's offering of metal in Oslo.]
John Dee's in Oslo is a surprising venue in many ways. As the smaller of the rooms available in the building on Torgatta you immediately expect it to be of perhaps a lower quality than a larger venue, yet overall the entire place was presented with a higher degree of class and quality than most venues of a similar size which I have visited here in the UK. Wide-ranging and extremely clean, well-laid out with two separate bars and a raised area at the back of the room, the venue worked perfectly for a metal show this evening. Kudos to the owners and staff of John Dee.
Unfortunately, the supports were not exactly of the same level of quality.
First up was Marionette, a Swedish band of whom I'd heard good things with regard to their brand of modern melo-death, influenced performance-wise by Japanese visual Kei. Unfortunately, they were, and are, routinely terrible. Embodying much of what has gone wrong with the melo-death sound in recent years, the band appeared onstage garbed in black shirts and white ties, each with their own "interesting" hair-style and accompanied by a singer in a pseudo-Japanese mask that lasted all of 30 seconds on his face. They came across as a bad metalcore band using keyboards and "wacky" imagery to appear interesting in a desperate attempt to appeal visually to angsty teens who think that Green Day are punk as fuck and My Chemical Romance have something important to say about the youth of today. (more after the jump . . .)
Plainly, I have too much time on my hands today. I didn't set out to do a THAT'S METAL! post, but the surfing of the web led me to some new discoveries that proved irresistible to me. You'll understand why in a moment.
It all started with Haate Kaate — a Bulgarian artist whose work we've featured before on this site, initially in a post about the most excellent album by German black-metal band Odem Arcarum, called Outrageous Reverie Above The Erosion Of Barren Earth, and then again in our longer review of that album.
We saw a MySpace bulletin about the album art she has just finished for a compilation CD due in December on the Ahnstern label called Oak Folk, which will include exclusive contributions by Agalloch, Allerseelen, Arnica, Changes, Dannagoischd, Fräkmündt, Hrefnesholt, Klammheim, Splinterskin, Sturmpercht, Waldteufel, Werra. This dovetailed with the news we discovered that Agalloch and Allerseelen will be joining together on a mini-tour of the West Coast in December (see one of our earlier posts today).
In trying to find out more about that Oak Folk compilation, I browsed the Ahnstern Facebook page. A post on that page in turn led me to the discovery that there is a town in Austria called . . . wait for it . . . Fucking. In learning more about that town, I also discovered the town of Wank in Germany.
Now, you know us well enough to understand that there was no way in hell we could resist adding a post about these towns to NCS, with a few of our typically tasteless embellishments. So, here goes . . . after the jump.
I guess this still qualifies as catching up. I just saw a notice on the Profound Lore web site that in tandem with the November 23 release of Marrow Of The Spirit, AGALLOCH have announced a West Coast tour with "Austrian industrial/neo-folk/martial ambient act Allerseelen." The tour begins on December 17 in Agalloch's hometown of Portland, Oregon, which will also serve as their record release show.
The number of tour dates is limited, and if you don't live on the West Coast of the U.S., this news probably won't do you much good. For us here in Seattle, the chance to see Agalloch on the heels of this new album release is just a fucking bonanza. The dates and places for the Agalloch/Allerseelen mini-tour are as follows:
12/17 – Portland, OR @ Berbati's Pan (w/Aerial Ruin)
12/18 – Seattle, WA @ Neumo's (w/Waldteufel, Alda)
12/21 – Los Angeles, CA @ The Proud Bird (w/Winterthrall)
12/22 – San Francisco, CA @ Great American Music Hall (w/Dispirit)
Yes, still catching up on developments in the world of metal that happened while I was on vacation. Yes, there's probably a better-than-even chance that you already saw some of this while I was fucking off, but maybe you didn't, or maybe you didn't pay close attention the first time around. So, here are a handful of additional items I thought were interesting as I slogged through the mountains of posts on a few metal blogs and/or Facebook and/or MySpace that appeared while I was away.
Today, we have for you a hot new video by Bloodshedd (The Philippines) and new music from Murder Construct (California), and Exist (Washington, DC).
In February of this year, we reviewed an album called Spare No One, released in 2009 on the Tower of Doom label by a band from The Philippines called Bloodshedd. We summed up our review with these words: "Trust us on this: If Bloodshedd were in the U.S. instead of the Phillipines, they'd be turning heads far and wide. They've sure spun our heads all the way around! This is blazingly creative music played with passion and top-shelf skill."
Well, while I was off on vacation, the band released their second official music video in support of Spare No One. It's for a song called "Beast 696". The video is another one of those band-playing-in-a-warehouse-or-alley concoctions, with fast cut-aways in the editing to keep pace with the blazing music. And oh hell, does it blaze — a buzzsaw of blackened thrash played with top-shelf instrumental skill and a knack for triggering neck-snap's. (more after the jump . . .)
[EDITOR'S NOTE: Today we're stepping aside again to make way for another album review by our UK contributor Andy Synn. It's about the latest release, In Dreams, from one of NCS's most beloved bands — AFTER THE BURIAL — but brace yourselves, because Andy is underwhelmed with the effort — and backs up his opinion in detail. Comments please!]
Apologies all, but I'm afraid this is going to be my first ever mainly negative review.
To qualify myself for this, I'd like to state that although I found Forging A Future Self to be a little stock for the majority of its running time, the band's sophomore release Rareform remains one of my favourite albums of the more modern iteration of metal. It's a skillful display of technicality and melody, mixed with a sense of interesting and progressive song-writing and a great sense of (non-derivative) Meshuggah-influenced groove. It had energy to spare and was organic in its ability to shift styles and tones.
Unfortunately, the third album In Dreams seems to have forgotten much of the positive growth demonstrated by Rareform, aiming for a more derivative and mass-appeal based sound. In a move similar to much of the "djent" movement (and also in a way reminiscent of the development of UK hardcore darlings Architects) the band have regressed to a more simplistic, and arguably less "metal", sound. Now whilst not every record needs to be "tr00", "kvlt", or whatever is the precisely elitist terminology of the day, this record comes across as rather forced and lacking in certain departments, leading me to wonder if the band have lost a lot of interest in the "metal" element of their sound. (more after the jump . . .)

subset: commoncrawl


text:
With a recent edition of Capitol Hill Report discussing what exactly takes place when you send a message to your elected officials, the next step is for you to learn just how little of an effort it takes to send the message itself. The Academy provides its members with an incredibly easy way to give feedback to their elected officials, all within a matter of moments: Vocus!
All it takes is the following:
And you're done!
"I've usually had difficulty sending email messages from organizations," said George W. Ellison, MD, San Diego. "Vocus makes this process simple."
Ellison contacted his elected officials after receiving an Action Alert, which members occasionally receive in their email. The subject line of these messages always start with "AAN Professional Association Action Alert": each is an issue-specific notification, asking you to log on to Vocus and send a message to your elected officials. Here is an example of a past Action Alert:
A hyperlink embedded in the message is (in this case, it is the word "contact") will take you straight to Vocus, from which you can quickly send a message to your members of Congress.
Now it's up to you to take the next step! When prompted, take the initiative to send a message to your elected officials. Remember, the more messages we send, the stronger neurology's voice becomes!
For questions or comments, please don't hesitate to contact Tim Miller, Health Policy Analyst, at email@example.com.


text:
Florida is known as the Sunshine State, but living there has a dark side, as the family of Jeff Bush discovered when the 36-year-old man was killed after a sinkhole opened beneath his house last week.
Authorities are now reporting the development of a second sinkhole in Seffner, Fla., just 2 miles (3 kilometers) from the sinkhole that destroyed the Bush home, according to NBC News.
Sinkholes are an increasingly deadly risk in Florida, due primarily to the region's geology. The state is largely underlain by porous limestone, which can hold immense amounts of water in underground aquifers. As groundwater slowly flows through the limestone, it forms a landscape called karst, known for features like caves, springs and sinkholes.
Workers remove belongings from the home where a sinkhole swallowed Jeffrey Bush on March 4, 2013 in Seffner, Florida. Jeff Bush, presumed dead after a sinkhole, estimated at 60 feet deep, opened under his bedroom while he was sleeping in the home.
The water in aquifers also exerts pressure on the limestone and helps to stabilize the overlying surface layer, usually clay, silt and sand in Florida. Sinkholes form when that layer of surface material caves in.
The collapse can be triggered by a heavy overload, often caused by a downpour or flooding, or when water gets pumped out of the ground. When water leaves the cavities within the limestone, the pressure that supported the surface material also goes. Depending on various factors, that overlying layer can give way abruptly, as it recently did in Florida, or gradually, said Ann Tihansky, a hydrologist with the U.S. Geological Survey (USGS) in Florida.
And Florida's groundwater has been disappearing rapidly as the state's population grows at breakneck speed: By 2015, Florida is expected to hit 20 million residents, making it the third-largest U.S. state, according to BusinessWeek.
To slake a thirsty state's population, Florida has been aggressively pumping out groundwater, destabilizing its limestone bedrock and contributing to the growing number of sinkholes, according to a USGS report.
Nowhere is this more true than in "Sinkhole Alley," the rapidly growing region of west-central Florida surrounding Tampa Bay, CNN.com reports. Sinkholes can also occur naturally, but from 2006 to 2010, the number of sinkhole claims to Florida insurance companies tripled, according to BusinessWeek.
Sinkholes are even more common in Florida during the winter months. "There's a high occurrence specifically in January or February," Tihansky told LiveScience. "And that's related to freezes, when farmers pump groundwater onto crops, strawberries and oranges, to protect them from freezing."
The other peak in sinkholes in Florida occurs in May and June, which are typically dry months with the year's lowest groundwater levels, Tihansky said.
These factors, combined with unstable rainfall patterns — the Tampa Bay region has had less than one-third its usual rainfall this year, according to the Minneapolis Star-Tribune — make sinkholes an ever-increasing threat to Floridians.
Full article…here


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This app has been deleted or is hidden to the public. There is extremely limited to no information about this app.
We don't even have a name, hence why we are displaying SteamDB Unknown App "AppID".
If you see someone screenshot a page like this and add some information/images on it, it is most likely fake.
Every change is tracked in history, and can be directly linked to.
|Billing Type
|Last Updated
|Steam Sub 95103
|CD Key
|February 18, 2016 – 22:36:11 UTC
|Steam Sub 95104
|CD Key
|February 18, 2016 – 22:36:11 UTC
|Steam Sub 95105
|Store or CD Key
|February 18, 2016 – 22:36:16 UTC


text:
The Cyber attack that is currently holding Sony hostage is exposing more scandal and throwing horrified executives under the bus, as emails and other incriminating correspondence is rapidly becoming public – for better or worse.
Jaden and Willow Smith, the offspring of star couple Will Smith Jada Pinkett Smith are the latest subjects of an email that has been leaked containing details that should have remained private when you consider the insulting tone of the message.
The email is in response to the controversial New York Times interview, in which both Jaden and Willow spewed out interesting reflections of the world at large and quite frankly sounded eerily intelligent in ways that gave readers and observers reason to pause and ponder.
Some people thought both kids were simply nuts while others were vocally impressed. Either way they proved they are not your typical Hollywood spoiled brats – desperate to follow in the footsteps of their famous parents.
Well, it looks like the executives at Sony found the interview to be quite disturbing and now there is proof in the form of an email chain between Tom Rothman, chairman of TriStar, Doug Belgrad, president of SPE's Motion Picture Group, and of course the always present Amy Pascal, SPE's co-chairman.
In the email, references were made about the New York Times interview that was interestingly titled: "Jaden and Willow Smith on Prana Energy, Time and Why School is Overrated."
Basically the email containing a link to the interview was passed around to the participants and it didn't receive glowing reviews – As Rothman sends the email to Belgrad – he writes in the body of the email: "they r home schooled: don't let this family date your movies!!!"
Ouch! It's clear that Sony has no intentions of working with the Smith kids anytime soon – which is weird because the studio is planning to release a Will Smith film sometime in 2016. Hmm…


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Vendee Globe Race 2012-2013 - Le Cam breaks away, Stamm in trouble
by Vendee Globe on 24 Dec 2012
Synerciel - 2012 Vendee Globe Jean-Marie Liot / DPPI / Vendée Globe
Bernard Stamm (Cheminées Poujoulat) was still working this morning (his night) to try and fix his hydrogenerators, re-join the race and preserve any hope of a place on the podium. The weather has hardened, with 16-18 knot northwesterlies sweeping down on the Auckland Islands, but Stamm has shelter in Sandy Bay, Enderby Island, in the northeast of the Archipelago, where he anchored at 0500hrs on Sunday morning.
The diversion has already cost the Swiss sailor at least 600 miles and he has fallen 1,481 miles behind the leaders.
He may well lose fifth place to as Jean Le Cam (SynerCiel), in sixth, He averaged 14.6 knots on a direct course overnight and is just 290 miles behind Stamm – less than a day's sailing at current speeds. If Stamm re-starts on Christmas Day, as is possible, then he will be chasing Le Cam in the Pacific.
Behind Le Cam, the nightmare of complicated routing continues for Mike Golding (Gamesa), Dominique Wavre (Mirabaud) and Javier Sansó (Acciona 100% EcoPowered), in horrible transition bubble of high pressure south of Tasmania. From their respective boat speeds they are still finding different conditions on the water than on the weather models. Golding (Gamesa) managed just 46.7 miles overnight at an average of 5.2 knots. It will be no consolation to him that he has arrived in the Pacific. Behind him Wavre (Mirabaud) fared a little better with 85 miles, but his progress has been complex and with a lot of effort Twisting further south Sansó made just 74 miles and will need another of his monumental catch-ups in the Pacific.
The losses may even be worse than they feared on Saturday, as they could have to wait 24 hours for some solid breeze to arrive from the southwest. On Friday they were still of a gang of four, now they are three because Le Cam is in a different weather system and flying away – 408 miles ahead of Golding, 475 miles ahead of Wavre and 703 miles ahead of Sansó.
Fleet News
After briefly losing the lead at the 1100hrs ranking on Sunday, Francois Gabart (MACIF) had won it back from Armel Le Cléac'h (Banque Populaire) by 1500hrs and has continued to be the fastest boat in the fleet since, averaging 19.7 knots overnight. But he is only 10.2 ahead and 0.7 of a knot faster than Le Clèac'h, with 25-27 westerlies behind them as they head northeast to the Pacific West gate.
Rarely has a Vendée Globe lead been so hotly contested – there have been 19 changes of lead since December.
Jean-Pierre Dick (Virbac-Paprec 3) lost some ground in third and is 518 miles behind, conceding 50-odd miles from his comeback. But he is further north and looks to have a good angle attack to the Pacific West gate.
As he anticipated Thomson has lost some speed. He made multiple gybes overnight as he heads northeast to the New Zealand gate around 200 miles ahead (depending on where he crosses). He averaged 12.1 knots overnight – his day and may have continued to make repairs to his hydrogenerators.
Behind Sansó the other four will all be pushed by a depression coming in from the north and bringing 30 knots of wind. That means more progress for Arnaud Boissières (Akena Verandas), as heads down to the East Australia gate, 350 miles southeast. He has been the fourth fastest over the last 24 hours, covering 364.8 miles more than twice as many as Sansó, who has made just 179.9 miles. He is 465 miles behind Sansó.
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