text:
Contact Us
Browse by:
Cooling system with variable duty cycle capacity control
Cooling system with variable duty cycle capacity control
Patent Drawings:
(16 images)
Pham, et al.
Date Issued:
June 24, 2008
December 8, 2003
Pham; Hung M
(Dayton, OH)
Singh; Abtar
(Kennesaw, GA)
Caillat; Jean-Luc
(Dayton, OH)
Bass; Mark
(Sidney, OH)
Emerson Climate Technologies, Inc.
(Sidney, OH)
Primary Examiner:
Tyler; Cheryl
Assistant Examiner:
Koca; Huseyin
Attorney Or Agent:
Harness, Dickey & Pierce, P.L.C.
U.S. Class:
Field Of Search:
International Class:
U.S Patent Documents:
Foreign Patent Documents:
0 281 317; 0 747 597
Other References:
A control system for a cooling system includes a first sensor for sensing a property indicative of demand for cooling and a controller coupled to the sensor. The controller produces the variable duty cycle control signal in response to the property and causes the compressor and valve to vary a cooling capacity of the cooling system in response to the variable duty cycle control signal. The sensor may sense the pressure, temperature, or both. The valve may be a suction-side pressure regulator or a liquid-side expansion valve of the solenoid or stepper type.
We claim:
1. A control system for a cooling system having a compressor and a valve, said control system comprising: a first sensor for sensing a property indicative of demand for cooling; acontroller coupled to said sensor and operable to produce a variable duty cycle control signal in response to said property, said controller modulating a capacity of said compressor and a position of said valve according to the same variable duty cyclecontrol signal to vary a cooling capacity of the cooling; and a diagnostic module for comparing said duty cycle with a value indicative of a system condition.
2. The control system of claim 1 wherein said sensor senses pressure and wherein said controller produces said variable duty cycle control signal with a variable cycle time that is a function of fluctuations in sensed pressure.
3. The control system of claim 1 wherein said first sensor is a temperature sensor.
4. The control system of claim 3, further comprising a pressure sensor coupled to said controller that produces a signal indicative of sensed pressure for use by the controller along with said property in generating said variable duty cyclecontrol signal.
5. The control system of claim 1 further comprising a pressure sensor in addition to said first sensor, said pressure sensor coupled to said controller.
6. The control system of claim 1 wherein said first sensor senses a property having a first rate of change and wherein said control system further comprises a second sensor that senses a second property having a second rate of change, saidsecond property used by said controller along with said property to produce said variable duty cycle control signal and said second rate of change being substantially greater than said first rate of change.
7. The control system of claim 6 wherein said first sensor senses changes in temperature and wherein said second sensor senses changes in pressure.
8. The control system of claim 1 wherein said controller varies said cooling capacity by selectively rendering compressing members of the compressor effective and ineffective.
9. The control system of claim 1 wherein controller provides said variable duty cycle control signal that cycles at a cycle time shorter than the time constant of the load.
10. The control system of claim 1 wherein said controller varies said cooling capacity between substantially one hundred percent capacity and substantially zero percent capacity.
11. The control system of claim 1 further comprising an alert module responsive to said diagnostic module for issuing an alert signal when said duty cycle bears a predetermined relationship to said value.
12. The control system of claim 1 wherein said valve is a suction-side pressure regulator.
13. The control system of claim 1 wherein said valve is a liquid-side expansion valve.
14. The control system of claim 1 wherein said valve is a pulsing solenoid valve.
15. The control system of claim 1 wherein said valve is a stepper valve.
16. A cooling system comprising: a refrigeration case; an evaporator disposed in said case; a condenser in fluid communication with said evaporator; an evaporator pressure regulator valve in fluid communication with said evaporator and saidcondenser; a pulse-width-modulated variable capacity compressor in fluid communication with said condenser, said evaporator, and said evaporator pressure regulator valve; a first sensor for sensing a property indicative of a demand for cooling; and acontroller responsive to said first sensor and providing a variable duty cycle control signal, said controller modulating a capacity of said compressor and a position of said evaporator pressure regulator valve according to the same variable duty cyclecontrol signal to vary a cooling capacity of the cooling system.
17. The cooling system of claim 16 further comprising a second refrigeration case having a second evaporator disposed therein, said second evaporator being coupled in fluid communication with said condenser.
18. The cooling system of claim 16 wherein said first sensor is a temperature sensor.
19. The cooling system of claim 18, further comprising a pressure sensor coupled to said controller that produces a signal indicative of sensed pressure for use by the controller along with a signal from said first sensor in generating saidvariable duty cycle control signal.
20. The cooling system of claim 16 wherein said controller produces said variable duty cycle control signal with a variable cycle time that is a function of fluctuations in pressure.
21. The cooling system of claim 16 further comprising a pressure sensor in addition to said first sensor, said pressure sensor coupled to said controller.
22. The cooling system of claim 16 wherein said valve includes a stepper motor.
23. The cooling system of claim 16 wherein said controller provides said variable duty cycle control signal that cycles at a cycle time shorter than the time constant of the load.
24. The cooling system of claim 16 wherein said controller varies cooling capacity between substantially one hundred percent capacity and substantially zero percent capacity.
25. The cooling system of claim 16 wherein said compressor is selectively operable in at least two states, said compressor comprising a pair of fluid compressing members and including a first state corresponding to a first capacity wherein saidpair of fluid compressing members are separated by a seal and a second state corresponding to a second capacity lower than said first capacity wherein said seal between said pair of fluid compressing members is broken.
26. The cooling system of claim 25 wherein said compressor pumps a refrigerant under pressure and wherein said controller produces said control signal with a variable cycle time that is a function of fluctuations in refrigerant pressure.
27. The cooling system of claim 25 wherein said compressor includes fluid compressing members and mechanism for selectively rendering said compressing members effective and ineffective to thereby assume said first state and said second state,respectively.
28. The cooling system of claim 25 wherein said compressor includes an electric motor and wherein said compressor is configured such that said electric motor remains energized in said first and second states.
29. The cooling system of claim 16 wherein said first sensor senses a property having a first rate of change and wherein said control system further comprises a second sensor that senses a second property having a second rate of change, saidsecond property used by said controller along with said property to produce said variable duty cycle control signal and said second rate of change being substantially greater than said first rate of change.
30. The cooling system of claim 29 wherein said first sensor senses changes in temperature and wherein said second sensor senses changes in pressure.
31. The cooling system of claim 16 wherein said compressor has two mechanical elements separated by a seal, said mechanical elements being movable relative to one another to develop fluid pressure and wherein said compressor includes mechanismto selectively break said seal in response to said control signal to thereby alter said fluid pressure developed while allowing said mechanical elements to maintain substantially constant relative movement with one another.
32. The cooling system of claim 16 wherein said compressor is a scroll compressor.
33. The cooling system of claim 16 wherein said controller produces a control signal that cycles at a cycle time at least four times shorter than the time constant of the load.
34. The cooling system of claim 16, wherein said evaporator pressure regulator valve is disposed in a suction line of said pulse-width-modulated variable capacity compressor.
35. The cooling system of claim 16, wherein said evaporator pressure regulator valve is disposed between an outlet of said evaporator and an inlet of said pulse-width-modulated variable capacity compressor.
The present invention relates generally to cooling systems, compressor control systems and refrigerant regulating valve control systems. More particularly, the invention relates to a refrigeration system employing a pulse width modulatedcompressor or evaporator stepper regulator controlled by a variable duty cycle signal derived from a load sensor. Preferably an adaptive controller generates the variable duty cycle signal. The compressor has two mechanical elements separated by aseal, and these mechanical elements are cyclically movable relative to one another to develop fluid pressure. The compressor includes a mechanism to selectively break the seal in response to the control signal, thereby modulating the capacity of thesystem.
The refrigeration system can be deployed as a distributed system in refrigeration cases and the like. The preferred arrangement allows the compressor and condenser subsystems to be disposed in or mounted on the refrigeration case, therebygreatly reducing the length of refrigerant conduit and refrigerant required.
Conventionally, refrigeration systems for supermarket refrigeration cases have employed air-cooled or water-cooled condensers fed by a rack of compressors. The compressors are coupled in parallel so that they may be switched on and off in stagesto adjust the system cooling capacity to the demands of the load. Commonly, the condensers are located outside, on the roof, or in a machine room adjacent the shopping area where the refrigeration cases are located.
Within each refrigeration case is an evaporator fed by lines from the condensers through which the expanded refrigerant circulates to cool the case. Conventionally, a closed-loop control system regulates refrigerant flow through the evaporatorto maintain the desired case temperature. Proportional-integral-derivative (PID) closed loop control systems are popular for this purpose, with temperature sensors and/or pressure sensors providing the sensed condition inputs.
It is common practice within supermarkets to use separate systems to supply different individual cooling temperature ranges: low temperature (for frozen foods, ice cream, nominally -25 F); medium (for meat, dairy products, nominally +20 F); high(for floral, produce, nominally +35 to +40 F). The separate low, medium and high temperature systems are each optimized to their respective temperature ranges. Normally, each will employ its own rack of compressors and its own set of refrigerantconduits to and from the compressors and condensers.
The conventional arrangement, described above, is very costly to construct and maintain. Much of the cost is associated with the long refrigerant conduit runs. Not only are long conduit runs expensive in terms of hardware and installationcosts, but the quantity of refrigerant required to fill the conduits is also a significant factor. The longer the conduit run, the more refrigerant required. Adding to the cost are environmental factors. Eventually fittings leak, allowing therefrigerant to escape to atmosphere. Invariably, long conduit runs involve more pipefitting joints that may potentially leak. When a leak does occur, the longer the conduit run, the more refrigerant lost.
There is considerable interest today in environmentally friendly refrigeration systems. Shortening the conduit run is seen as one way to achieve a more environmentally friendly system. To achieve this, new condenser/compressor configurationsand new control systems will need to be engineered.
Re-engineering condenser/compressor configurations for more environmentally friendly systems is not a simple task, because system efficiency should not be sacrificed. Generally, the conventional roof-mounted condenser system, supplied bycondensers, benefits from economies of scale and is quite efficient. These systems serve as the benchmark against which more environmentally friendly systems of the future will need to be measured.
To appreciate why re-engineering an environmentally yet efficient system has proven so difficult, consider these thermodynamic issues. The typical refrigeration case operates in a very unpredictable environment. From a design standpoint, thethermal mass being cooled is rarely constant. Within the supermarket environment, the temperature and humidity may vary widely at different times of day and over different seasons throughout the year. The product load (items in the refrigeration case)can also change unpredictably. Customers removing product and store clerks replenishing product rarely synchronize. Outside the supermarket environment, the outdoor air temperature and humidity may also vary quite widely between day and night and/orbetween summer and winter. The capacity of the system must be designed for the harshest conditions (when the condenser environment is the hottest). Thus systems may experience excess capacity in less harsh conditions, such as in the cool evenings orduring the winter.
Periodic defrosting also introduces thermal fluctuations into the system. Unlike thermal fluctuations due to environmental conditions, the thermal fluctuations induced by the defrost cycle are cause by the control system itself and not by thesurrounding environment.
In a similar fashion, the control system for handling multiple refrigeration cases can induce thermal fluctuations that are quite difficult to predict. If all cases within a multi-case system are suddenly turned on at once--to meet theirrespective cooling demands--the cooling capacity must rapidly be ramped up to maximum. Likewise, if all cases are suddenly switched off, the cooling capacity should be ramped down accordingly. However, given that individual refrigeration cases mayoperate independently of one another, the instantaneous demand for cooling capacity will tend to vary widely and unpredictably.
These are all problems that have made the engineering of environmentally friendly systems more difficult. Adding to these difficulties are user engineering/ergonomic problems. The present day PID controller can be difficult to adapt todistributed refrigeration systems. Experienced controls engineers know that a well-tuned PID controller can involve a degree of artistry in selecting the proper control constants used in the PID algorithm. In a large refrigeration system of theconventional architecture (non-distributed) the size of the system justifies having a controls engineer visit the site (perhaps repeatedly) to fine tune the control constant parameters.
This may not be practical for distributed systems in which the components are individually of a much smaller scale and far more numerous. By way of comparison, a conventional system might employ one controller for an entire multi-case,store-wide system. A distributed system for the same store might involve a controller for each case or adjacent group of cases within the store. Distributed systems need to be designed to minimize end user involvement. It would therefore be desirableif the controller were able to auto configure. Currently control systems lack this capability.
The present invention provides a distributed refrigeration system in which the condenser is disposed on the refrigeration case and serviced by a special pulse width modulated compressor that may be also disposed within the case. If desired, thecondenser and compressor can be coupled to service a group of adjacent refrigeration cases, each case having its own evaporator. The pulse width modulated compressor employs two mechanical elements, such as scroll members, that move rotationallyrelative to one another to develop fluid pressure for pumping the refrigerant. The compressor includes a mechanism that will selectively break the seal between the two mechanical elements, thereby altering the fluid pressure developed by the compressorwhile allowing the mechanical elements to maintain substantially constant relative movement with one another. The compressor can be pulse width modulated by making and breaking the fluid seal without the need to start and stop the electric motor drivingthe mechanical elements.
The pulse width modulated compressor is driven by a control system that supplies a variable duty cycle control signal based on measured system load. The controller may also regulate the frequency (or cycle time) of the control signal to minimizepressure fluctuations in the refrigerant system. The on time is thus equal to the duty cycle multiplied by the cycle time, where the cycle time is the inverse of the frequency.
The refrigeration system of the invention has a number of advantages. Because the instantaneous capacity of the system is easily regulated by variable duty cycle control, an oversized compressor can be used to achieve faster temperature pulldown at startup and after defrost, without causing short cycling as conventional compressor systems would. Another benefit of variable duty cycle control is that the system can respond quickly to sudden changes in condenser temperature or casetemperature set point. The controller adjusts capacity in response to disturbances without producing unstable oscillations and without significant overshoot. Also, the ability to match instantaneous capacity to the demand allows the system to operateat higher evaporator temperatures. (Deep drops in temperature experienced by conventional systems at overcapacity are avoided.)
Operating at higher evaporator temperatures reduces the defrost energy required because the system develops frost more slowly at higher temperatures. Also, the time between defrosts can be lengthened by a percentage proportional to theaccumulated runtime as dictated by the actual variable duty cycle control signal. For example, a sixty percent duty cycle would increase a standard three-hour time between defrosts to five hours (3/.60=5).
The pulse width modulated operation of the system yields improved oil return. The refrigerant flow pulsates between high capacity and low capacity (e.g. 100% and 0%), creating more turbulence which breaks down the oil boundary layer in the heatexchangers.
Another benefit of the variable duty cycle control system is its ability to operate with a variety of expansion devices, including the simple orifice, the thermal expansion valve (TXV) and the electronic expansion valve. A signal derived fromthe expansion device controller can be fed to the compressor controller of the invention. This signal allows the variable duty cycle control signal and/or its frequency to be adjusted to match the instantaneous operating conditions of the expansiondevice. A similar approach may be used to operate variable speed fans in air cooled condenser systems. In such case the controller of the invention may provide a signal to control fan speed based on the current operating duty cycle of the compressor.
Yet another benefit of the invention is its ability to detect when the system is low on refrigerant charge, an important environmental concern. Low refrigerant charge can indicate the presence of leaks in the system. Low charge may be detectedby observing the change in error between actual temperature and set point temperature as the system duty cycle is modulated. The control system may be configured to detect when the modulation in duty cycle does not have the desired effect on temperaturemaintenance. This can be due to a loss of refrigerant charge, a stuck thermal expansion valve or other malfunctions.
For a more complete understanding of the invention, its objects and advantages, refer to the following specification and to the accompanying drawings.
FIG. 1 is a system block diagram of a prior art refrigeration system configuration;
FIG. 2 is a block diagram of a refrigeration system in accordance with the present invention;
FIG. 3 is a cross-sectional view of an embodiment of the pulse width modulated compressor, shown in the loaded state;
FIG. 4 is a cross-sectional view of the compressor of FIG. 3, shown in the unloaded state;
FIG. 5 is another embodiment of a refrigeration or cooling system in accordance with the present invention;
FIG. 6 is a block diagram of the controller;
FIG. 7 is a block diagram showing how the controller may be used to modulate an evaporator stepper regulator;
FIG. 8 is a block diagram of the signal conditioning module of the controller of FIG. 6;
FIG. 9 is a block diagram of the control module of the controller of FIG. 6;
FIG. 10 is a state diagram depicting the operating states of the controller;
FIG. 11 is a flowchart diagram illustrating the presently preferred Pi control algorithm;
FIG. 12 is a waveform diagram illustrating the variable duty cycle signal produced by the controller and illustrating the operation at a constant frequency;
FIG. 13 is a waveform diagram of the variable duty cycle signal, illustrating variable frequency operation;
FIG. 14 is a series of graphs comparing temperature and pressure dynamics of system employing the invention with a system of conventional design;
FIG. 15 is a block diagram illustrating the adaptive tuning module of the invention;
FIG. 16a is a flowchart diagram illustrating the presently preferred operation of the adaptive tuning module, specifically with respect to the decision whether to start tuning;
FIG. 16b is a flowchart diagram illustrating the presently preferred process performed by the adaptive tuning module in the integration mode;
FIG. 16c is a flowchart diagram illustrating the operation of the adaptive tuning module in the calculation mode;
FIG. 17 is a state diagram illustrating the operative states of the adaptive tuning module;
FIG. 18 is a block diagram illustrating the fuzzy logic block of the adaptive tuning loop;
FIG. 19 is a membership function diagram for the fuzzy logic block of FIG. 18;
FIG. 20 is a truth table relating to the membership function of FIG. 19 as used by the fuzzy logic block of FIG. 18;
FIG. 21 is an output membership function diagram for the fuzzy logic block of FIG. 18; and
FIG. 22 is a schematic illustrating exemplary sensor locations for control-related and diagnostic-related functions of the present invention.
FIG. 1 illustrates how a conventional supermarket refrigeration system is configured. As previously discussed, it is conventional practice to place the compressors 30 and the condenser 32 in a location remote from the refrigeration cases 34. Inthis illustration, the compressors 30 are configured in a parallel bank located on the roof 36 of the building. The bank of compressors supply a large condenser 32, which may be air cooled or water cooled. The condenser supplies liquid refrigerant to areceiver 38. The receiver 38, in turn, supplies the individual refrigeration cases, which are connected in parallel, as illustrated. In most implementations a liquid line solenoid valve 40 is used to regulate flow to the associated evaporator 42. Therefrigerant is supplied to the evaporator through a suitable expansion device such as expansion valve 44. The expansion valve 44 provides a restricted orifice that causes the liquid refrigerant to atomize into liquid droplets that are introduced intothe inlet side of the evaporator 42. The evaporator 42, located within the refrigeration case 34, extracts heat from the case and its contents by vaporization of the liquid refrigerant droplets into a gas. The compressors 30 extract this gas by suctionand compress it back into the liquid state. The liquid refrigerant is then cooled in the condenser 32 and returned to the receiver 38, whereupon the cycle continues.
To match cooling capacity to the load, the compressors 30 may be switched on and off individually or in groups, as required. In a typical supermarket arrangement there may be several independent systems, each configured as shown in FIG. 1, tohandle different operating temperature ranges. Note that the liquid line 46 and the suction line 48 may each need to be quite lengthy (e.g., up to 150 feet) to span the distance from refrigeration case to roof.
FIG. 2 shows a refrigeration case 34 configured according to the principles of the present invention. The condenser 32 and compressor 30 are both disposed within case 34 or attached thereto. Evaporator 42 and the associated expansion valve 44are likewise disposed within case 34. The condenser 32 is provided with a heat removal mechanism 50 by which heat is transferred to ambient. The heat removal mechanism can be a water jacket connected to suitable plumbing for carrying waste heat to awater cooling tower located on the building roof. Alternatively, the heat removal mechanism can be a forced-air cooling system or a passive convection-air cooling system.
The refrigeration system of the invention employs a compressor controller 52 that supplies a pulse width modulated control signal on line 54 to a solenoid valve 56 on compressor 30. The compressor controller adjusts the pulse width of thecontrol signal using an algorithm described below. A suitable load sensor such as temperature sensor 58 supplies the input signal used by the controller to determine pulse width.
FIGS. 3 and 4 show the details of compressor 30. FIG. 3 shows the compressor in its loaded state and FIG. 4 shows the compressor in its unloaded state. The solenoid valve 56 switches the compressor between these two states while the compressormotor remains energized. One important advantage of this configuration is that the compressor can be pulse width modulated very rapidly between the loaded and unloaded states without interrupting power to the compressor motor. This pulse widthmodulated cycling exerts less wear on the compressor, because the motor is not subjected to sudden changes in angular momentum.
Referring to FIGS. 3 and 4, there is shown an exemplary compressor 30. Compressor 30 may be used within a hermetic scroll compressor such as generally of the type described in assignee's U.S. Pat. No. 5,102,316.
The exemplary compressor 30 includes an outer shell 61 and an orbiting scroll member 64 supported on upper bearing housing 63 and drivingly connect to crankshaft 62 via crank pin 65 and drive bushing 60. A second non-orbiting scroll member 67 ispositioned in meshing engagement with scroll member 64 and axially movably secured to upper bearing housing 63. A partition plate 69 is provided adjacent the upper end of shell 61 and serves to define a discharge chamber 70 at the upper end thereof.
In operation, as orbiting scroll member 64 orbits with respect to scroll member 67, suction gas is drawn into shell 61 via suction inlet 71 and thence into compressor 30 through inlet 72 provided in non-orbiting scroll member 67. Theintermeshing wraps provided on scroll members 64 and 67 define moving fluid pockets which progressively decrease in size and move radially inwardly as a result of the orbiting motion of scroll member 64 thus compressing the suction gas entering via inlet72. The compressed gas is then discharged into discharge chamber 70 via discharge port 73 provided in scroll member 67 and passage 74.
In order to unload compressor 30, solenoid valve 56 will be actuated in response to a signal from control module 87 to interrupt fluid communication to increase the pressure within chamber 77 to that of the discharge gas. The biasing forceresulting from this discharge pressure will overcome the sealing biasing force thereby causing scroll member 67 to move axially upwardly away from orbiting scroll member 64. This axial movement will result in the creation of a leakage path between therespective wrap tips and end plates of scroll members 64 and 67 thereby substantially eliminating continued compression of the suction gas.
A flexible fluid line 91 extends from the outer end of passage 90 to a fitting 92 extending through shell 61 with a second line 93 connecting fitting 92 to solenoid valve 56. Solenoid valve 56 has fluid lines 82 and 84 connected to suction line83 and discharge line 85 and is controlled by control module 87 in response to conditions sensed by sensor 88 to effect movement of non-orbiting scroll member 67 between the positions shown in FIGS. 3 and 4.
When compression of the suction gas is to be resumed, solenoid valve 56 will be actuated so as to move scroll member 67 into sealing engagement with scroll member 64.
The refrigeration case embodiment of FIG. 2 may be packaged as a self-contained unit. While that may be a desirable configuration for many applications, the invention is not restricted to stand alone, self-contained refrigeration caseconfigurations. Rather, the invention lends itself to a variety of different distributed refrigeration systems. FIG. 5 shows an example of such a distributed system.
Referring to FIG. 5, a single compressor 30 and condenser 32 can service several distributed refrigeration cases or several distributed cooling units in a heating and cooling (HVAC) system. In FIG. 5 the refrigeration cases or cooling systemhousings are shown as dashed boxes, designated 34a, 34b, and 34c. Conveniently, the compressor 30 and condenser 32 may be disposed within or attached to one of the refrigeration cases or housings, such as refrigeration case or housing 34a.
Each refrigeration case or housing has its own evaporator and associated expansion valve as illustrated at 42(a, b, c) and 44(a, b, c). In addition, each refrigeration case or housing may have its own temperature sensor 58(a, b, c) supplyinginput information to the compressor controller 52. Finally, a pressure sensor 60 monitors the pressure of the suction line 48 and supplies this information to compressor controller 52. The compressor controller supplies a variable duty cycle signal tothe solenoid valve 56 as previously described.
The multiple case or multiple cooling unit embodiment of FIG. 5 shows how a single compressor can be pulse width modulated by compressor controller 52 to supply the instantaneous demand for cooling. The temperature sensors 58(a, b, c)collectively provide an indication of the load on the system, as does pressure sensor 60. The controller adjusts the pulse width of the control signal to modulate the compressor between its high capacity and low capacity states (100%, 0%) to meet theinstantaneous demand for refrigerant.
As an alternate control technique, one or more of the suction lines exiting the evaporator can be equipped with an electrically controlled valve, such as an evaporator pressure regulator valve 45c. Valve 45c is coupled to controller 52, asillustrated. It may be supplied with a suitable control signal, depending on the type of the valve. A stepper motor valve may be used for this purpose, in which case controller 30 would supply a suitable signal to increment or decrement the setting ofthe stepper motor to thereby adjust the orifice size of the valve. Alternatively, a pulse width modulated valve could be used, in which case it may be controlled with the same variable duty cycle signal as supplied to the compressor 30.
Controller 52 is not limited to solely compressor control applications. The variable duty cycle control signal can also be used to control other types of refrigerant flow and pressure control devices, such as refrigerant regulating valves. FIG.7 shows such an application, where the output of controller 52 supplies control signals to evaporator stepper regulator 43. This device is a fluid pressure regulator that is adjusted by stepper motor 45. The evaporator stepper regulator (ESR) valve 43adjusts the suction pressure to thereby adjust the capacity of the system.
A block diagram of the presently preferred compressor controller is illustrated in FIG. 6. A description of the various signals and data values shown in this and successive figures is summarized in Table I below.
TABLE-US-00001 TABLE I Default No. Variable Name Value Description 1 Signal Conditioning: Sensor Alarm False Indicates Sensor Reading is not within expected range Sensor Mode Min User configuration to indicate if Min/Max/Avg is performed for alltemperature Sensors Sampling Time (Ts) 0.5 sec Rate at which Signal conditioning block is executed Control Type T/P Type if controlled by only Temp. or both Temp. & Pressure 2 Control Block: Sensor Alarm False Same as before System Alarm False Generatedby Adaptive Block indicative some system problem SSL 0 Steady state loading % Defrost Status False Whether system is in defrost Pull_Down_Time 0 Time taken to pull down after defrost Gain (K) 7 Gain used in PI algorithm Integral Time (Ti) 100 used in PIControl Time (Tc) 10 Sec used in PI Control Set Pt. (St) 0 F used in PI Operating State 1 What state the machine is operating at 3 Defrost Control Defrost Status False If defrost status of the case Defrost Type External If the defrost is from externaltimer or Internal clock of controller Defrost Interval 8 hrs Time between defrost Defrost Duration 1 hr Defrost Duration Defrost Termination 50 F Termination temperature for Temp. defrost
At the heart of the controller is control block module 102. This module is responsible for supplying the variable duty cycle control signal on lead 104. Module 102 also supplies the compressor ON/OFF signal on lead 106 and an operating statecommand signal on lead 108. The compressor ON/OFF signal drives the contactors that supply operating current to the compressor motor. The operating state signal indicates what state the state machine (FIG. 10) is in currently.
The control block module receives inputs from several sources, including temperature and pressure readings from the temperature and pressure sensors previously described. These temperature readings are passed through signal conditioning module110, the details of which are shown in the pseudocode Appendix. The control block module also receives a defrost status signal from defrost control module 112. Defrost control module 112 contains logic to determine when defrost is performed. Thepresent embodiment allows defrost to be controlled either by an external logic signal (supplied through lead 114) or by an internal logic signal generated by the defrost control module itself. The choice of whether to use external or internal defrostcontrol logic is user selectable through user input 116. The internal defrost control uses user-supplied parameters supplied through user input 118.
The preferred compressor controller in one form is autoconfigurable. The controller includes an optional adaptive tuning module 120 that automatically adjusts the control algorithm parameters (the proportional constant K) based on operatingconditions of the system. The adaptive tuning module senses the percent loading (on lead 104) and the operating state (on lead 108) as well as the measured temperature after signal conditioning (on lead 122). Module 120 supplies the adaptive tuningparameters to control block 102, as illustrated. The current embodiment supplies proportional constant K on lead 124 and SSL parameter on lead 126, indicative of steady-state loading percent. A system alarm signal on lead 126 alerts the control blockmodule when the system is not responding as expected to changes in the adaptively tuned parameters. The alarm thus signals when there may be a system malfunction or loss of refrigerant charge. The alarm can trigger more sophisticated diagnosticroutines, if desired. The compressor controller provides a number of user interface points through which user-supplied settings are input. The defrost type (internal/external) input 116 and the internal defrost parameters on input 118 have already beendiscussed. A user input 128 allows the user to specify the temperature set point to the adaptive tuning module 120. The same information is supplied on user input 130 to the control block module 102. The user can also interact directly with thecontrol block module in a number of ways. User input 132 allows the user to switch the compressor on or off during defrost mode. User input 134 allows the user to specify the initial controller parameters, including the initial proportional constant K.The proportional constant K may thereafter be modified by the adaptive tuning module 120. User input 136 allows the user to specify the pressure differential (dP) that the system uses as a set point.
In addition to these user inputs, several user inputs are provided for interacting with the signal conditioning module 110. User input 138 selects the sensor mode of operation for the signal conditioning module. This will be described in moredetail below. User input 140 allows the user to specify the sampling time used by the signal conditioning module. User input 142 allows the user to specify whether the controller shall be operated using temperature sensors only (T) or temperature andpressure sensors (T/P).
Referring now to FIG. 8, the signal conditioning module is shown in detail. The inputs (temperature and/or pressure sensors) are shown diagrammatically at 144. These inputs are processed through analog to digital convertor 146 and then suppliedto the control type selector 148. Temperature readings from the temperature and/or pressure sensors are taken sequentially and supplied serially through the analog to digital convertor. The control type selector codes or stores the data so thatpressure and temperature values are properly interpreted.
Digital filtering is then applied to the signal at 150 to remove spurious fluctuations and noise. Next, the data are checked in module 152 to ensure that all readings are within expected sensor range limits. This may be done by converting thedigital count data to the corresponding temperature or pressure values and checking these values against the pre-stored sensor range limits. If the readings are not within sensor range an alarm signal is generated for output on output 154.
Next a data manipulation operation is performed at 156 to supply the temperature and/or pressure data in the form selected by the sensor mode user input 138. The current embodiment will selectively average the data or determine the minimum ormaximum of the data (Min/Max/Avg). The Min/Max/Avg mode can be used to calculate the swing in pressure differential, or a conditioned temperature value. The average mode can be used to supply a conditioned temperature value. These are shown as outputs158 and 160, respectively.
FIG. 9 shows the control block module in greater detail. The conditioned temperature or pressure signal is fed to calculation module 162 that calculates the error between the actual temperature or pressure and the set point temperature orpressure. Module 162 also calculates the rate of change in those values.
The control block module is designed to update the operating state of the system on a periodic basis (every T.sub.c seconds, nominally once every second). The Find Operating State module 164 performs this update function. The state diagram ofFIG. 10 provides the details on how this is performed. Essentially, the operating state advances, from state to state, based on whether there is a sensor alarm (SA) present, whether there is a defrost status signal (DS) present and what the calculatederror value is. The Find Operating State module 164 supplies the operating state parameter and the Pull Down Time parameter to the decision logic module 166.
Referring to FIG. 10, the Find Operating State module 164 advances from state to state as follows. Beginning in the initial state 168 the module advances to the normal operating state 170 after initialization. It remains in that state untilcertain conditions are met. FIG. 10 shows by label arrows what conditions are required to cycle from the normal operating state 170 to the defrost state 172; to the pull down state 174; to the sensor alarm pull down state 176; to the sensor alarmoperating state 178 and to the sensor alarm defrost state 180.
The decision logic module 166 (FIG. 9) determines the duty cycle of the variable duty cycle signal. This is output on lead 182, designated % Loading. The decision logic module also generates the compressor ON/OFF signal on lead 184. The actualdecision logic will be described below in connection with FIG. 11. The decision logic module is form of proportional integral (PI) control that is based on an adaptively calculated cycle time T.sub.cyc. This cycle time is calculated by the calculationmodule 186 based on a calculated error value generated by module 188. Referring back to FIG. 6, the conditioned pressure differential signal on lead 122 (Cond dP) is supplied to the Calculate Error module 188 (FIG. 9) along with the pressuredifferential set point value as supplied through user input 136 (FIG. 6). The difference between actual and set point pressure differentials is calculated by module 188 and fed to the calculation module 186. The adaptive cycle time T.sub.cyc is afunction of the pressure differential error and the operating state as determined by the find operating state module 164 according to the following calculation: T.sub.cyc(new)=T.sub.cyc(old)+K.sub.c* Error (1) where:
K.sub.c: proportional constant; and
Error: (actual-set point) suction pressure swing.
The presently preferred PI control algorithm implemented by the decision logic module 166 is illustrated in FIG. 11. The routine begins at step 200 by reading the user supplied parameters K, T.sub.i, T.sub.c and S.sub.t. See FIG. 6 for adescription of these user supplied values. The constant K.sub.p is calculated as being equal to the initially supplied value K; and the constant K.sub.i is calculated as the product of the initially supplied constant K and the ratio T.sub.c/T.sub.i.
Next, at step 202 a decision is made whether the absolute value of the error between set point temperature and conditioned temperature (on lead 190, FIG. 9) is greater than 5.degree. F. If so, the constant K.sub.p is set equal to zero in step204. If not, the routine simply proceeds to step 206 where a new loading percent value is calculated as described by the equation in step 206 of FIG. 11. If the load percent is greater than 100 (step 208), then the load percent is set equal to 100% atstep 210. If the load percent is not greater than 100% but is less than 0% (step 212 ) the load percent is set equal to 0% at step 214. If the load percent is between the 0% and 100% limits, the load percent is set equal to the new load percent at step216.
The variable duty cycle control signal generated by the controller can take several forms. FIGS. 12 and 13 give two examples. FIG. 12 shows the variable duty cycle signal in which the duty cycle varies, but the frequency remains constant. InFIG. 12, note that the cycle time, indicated by hash marks 220, are equally spaced. By comparison, FIG. 13 illustrates the variable duty cycle signal wherein the frequency is also varied. In FIG. 13, note that the hash marks 220 are not equally spaced. Rather, the waveform exhibits regions of constant frequency, regions of increasing frequency and regions of decreasing frequency. The variable frequency illustrated in FIG. 13 is the result of the adaptive modulation of the cycle time T.sub.cyc.
FIG. 14 graphically shows the benefits that the control system of the invention has in maintaining tighter temperature control and higher suction pressure with improved system efficiency. Note how the temperature curve 222 of the inventionexhibits considerably less fluctuation than the corresponding temperature curve 224 of a conventional controller. Similarly, note that the pressure curve 226 of the invention has a baseline well above that of pressure curve 228 of the conventionalcontroller. Also, the peak-to-peak fluctuation in pressure exhibited by the invention (curve 226) is much smaller than that of the conventional controller (curve 228).
The controller of the invention operates at a rate that is at least four times faster (typically on the order of at least eight times faster) than the thermal time constant of the load. In the presently preferred embodiment the cycle time of thevariable duty cycle signal is about eight times shorter than the time constant of the load. By way of non-limiting example, the cycle time of the variable duty cycle signal might be on the order of 10 to 15 seconds, whereas the time constant of thesystem being cooled might be on the order of 1 to 3 minutes. The thermal time constant of a system being cooled is generally dictated by physical or thermodynamic properties of the system. Although various models can be used to describe the physical orthermodynamic response of a heating or cooling system, the following analysis will demonstrates the principle.
Modeling the Thermal Time Constant of the System Being Cooled.
One can model the temperature change across the evaporator coil of a refrigeration system or heat pump as a first order system, wherein the temperature change may be modeled according to the following equation:.DELTA.T=.DELTA.T.sub.ss[1-exp(-t/.gamma.)]+.DELTA.T.sub.0exp(-.tau./.gam- ma.). where: .DELTA.T=air temperature change across coil .DELTA.T.sub.ss=steady state air temperature change across coil .DELTA.T.sub.0=air temperature change across the coil attime zero t=time .gamma.=time constant of coil. The transient capacity of the unit can be obtained by multiplying the above equation by the air mass flow rate (m) and specific heat at constant pressure (C.sub.p) and integrating with respect to time. the time required to reach steady state operating condition, and thus the steady state temperature change across the condenser coil. If desired, the system can be modeled using two time constants, one based on the mass of the coil and another based onthe time required to get the excess refrigerant from the evaporator into the rest of the system. In addition, it may also be desirable to take into account, as a further time delay, the time lag due to the large physical distance between evaporator andcondenser coils in some systems.
The thermal response of the evaporator coil may be modeled by the following equation: =1/2[(1-e.sup.1/.gamma.1)+(1-e.sup.1/.gamma.2)] where: =temperature change across coil/steady state temperature change across coil t=time .gamma..sub.1=timeconstant based on mass of coil .gamma..sub.2=time constant based on time required to remove excess refrigerant from evaporator
In practice, the controller of the invention cycles at a rate significantly faster than conventional controllers. This is because the conventional controller cycles on and off in direct response to the comparison of actual and set-pointtemperatures (or pressures). In other words, the conventional controller cycles on when there is demand for cooling, and cycles off when the error between actual and set-point temperature is below a predetermined limit. Thus the on-off cycle of theconventional controller is very highly dependent on the time constant of the system being cooled.
In contrast, the controller of the invention cycles on and off at a rate dictated by calculated values that are not directly tied to the instantaneous relation between actual and set-point temperatures or pressures. Rather, the cycle time isdictated by both the cycle rate and the duty cycle of the variable duty cycle signal supplied by the controller. Notably, the point at which the controller cycles from on to off in each cycle is not necessarily the point at which the demand for coolinghas been met, but rather the point dictated by the duty cycle needed to meet the demand.
Adaptive Tuning
The controller Geneva described above can be configured to perform a classic control algorithm, such as a conventional proportional-integral-derivative (PID) control algorithm. In the conventional configuration the user would typically need toset the control parameters through suitable programming. The controller may also be of an adaptive type, described here, to eliminate the need for the user to determine and program the proper control parameters.
Thus, one important advantage of the adaptive controller is its ability to perform adaptive tuning. In general, tuning involves selecting the appropriate control parameters so that the closed loop system is stable over a wide range of operatingconditions, responds quickly to reduce the effect of disturbance on the control loop and does not cause excessive wear of mechanical components through continuous cycling. These are often mutually exclusive criteria, and a compromise must generally bemade. In FIG. 18 (and also FIG. 6) there are two basic control loops: the refrigeration control loop and the adaptive tuning loop. The refrigeration control loop is administered by control block module 102; the adaptive loop is administered by adaptivetuning module 120. Details of the adaptive tuning module 120 are shown in FIGS. 15, 16a-16c and 17. The presently preferred adaptive tuning module uses a fuzzy logic control algorithm that will be described in connection with FIGS. 18-20.
Referring to FIG. 15, the adaptive tuning module performs basically three functions. First, it decides whether to perform adaptive tuning. This is handled by module 240. Second, it gathers the needed parameters for performing adaptive tuning. This is handled by module 242. Third, it calculates the adaptive gain used by the control loop. This is handled by module 244.
Module 240 bases the decision on whether to start tuning upon two factors: the current operating state of the system and the control set point. The flowchart of FIG. 16a shows the steps involved in this decision. Module 242 integrates keyparameters needed for the calculations performed by module 244. Essentially, module 242 inputs the percent loading, the temperature and pressure values and the set point temperature. It outputs the following data: S_ER (the total number of conditionedtemperature and pressure data points that are within 0.5 degrees or 1 Psig of the set point value), S_Close (the total number of percent loading data points that goes to zero percent during a given sampling interval, e.g. 30 min.), S_Open (the totalnumber of percent loading data points that goes to 100% in the sampling interval) and SSLP (a moving average or rolling average of the percent loading during the sampling interval). Module 242 is responsive to a tuning flag that is set by module 240. Module 242 performs the integration of these key parameters when signaled to do so by the tuning flag. FIG. 16b shows the steps involved in performing integration of these key parameters.
Finally, the calculation block takes the data supplied by module 242 and calculates the adaptive gain using the process illustrated in FIG. 16c.
The adaptive tuning module 120 will cycle through various operating states, depending on the state of a timer. FIG. 17 is a state diagram showing how the presently preferred embodiment will function. Note that the sequence transitions from theinitialization mode to either the integration mode or the no tuning mode, depending on whether the tuning flag has been set. Once in the integration mode, the system performs integration until the timer lapses (nominally 30 minutes), whereupon thecalculation mode is entered. Once the calculations are completed the timer is reset and the system returns to the initialization mode.
The block diagram of the adaptive scheme is shown in FIG. 18. There are two basic loops--The first one is the PID control loop 260 that runs every "dt" second and the second is the adaptive loop 262 that runs every "ta" second. When the controlsystem starts, the PID control loop 260 uses a default value of gain (K) to calculate the control output. The adaptive loop 262, checks the error e(t) 264 every "ta" seconds 266 (preferably less than 0.2*dt seconds). At module 268 if the absolute valueof error, e(t), is less than desired offset (OS), a counter Er_new is incremented. The Offset (OS) is the acceptable steady-state error (e.g. for temperature control it may be +/1.degree. F.). This checking process continues for "tsum" seconds 270(preferably 200 to 500 times dt seconds). After "tsum" seconds 270, the value Er_new is converted into percentage (Er_new % 272). The parameter Er_new % 272 indicates the percentage of sampled e(t) that was within accepted offset (OS) for "tsum" time. In other words, it is a measure of how well the control variable was controlled for past "tsum" seconds. A value of 100% means "tight" control and 0% means "poor" control. Whenever Er_new % is 100%, the gain remains substantially unchanged as itindicates tighter control. However, if Er_new happens to be between 0 and 100%, adaptive fuzzy-logic algorithm module 274 calculates a new gain (K_new 276) that is used for next "tsum" seconds by the control algorithm module 278.
In the preferred embodiment, there is one output and two inputs to the fuzzy-logic algorithm module 274. The output is the new gain (K_new) calculated using the input, Er_new %, and a variable, Dir, defined as follows: Dir=Sign[(ER-new %-ER_old%)*(K_new-K-old)] (2)
where: Sign stands for the sign (+ve, -ve or zero) of the term inside the bracket; Er_new % is the percentage of e(t) that is within the offset for past "tsum" seconds; Er_old % is the value of Er_new % in "(tsum-1)" iteration; K_new is the gainused in "tsum" time; and K_old is the gain in (tsum-1) time.
For example, suppose the controller starts at 0 seconds with a default value of K=10 and, ta=1 seconds, tsum=1000 seconds and OS=1. Suppose 600 e(t) data out of a possible 1000 data was within the offset. Therefore, after 1000 sec, Er_new %=60(i.e., 600/1000*100), K_new=10. Er_old % and K_old is set to zero when the adaptive fuzzy-logic algorithm module 274 is used the first time. Plugging these numbers in Eq.(2) gives the sign of the variable "Dir" as positive. Accordingly, the inputs tothe adaptive fuzzy-logic module 274 for the first iteration are respectively, Er_new %=60 and Dir=+ve.
The next step is to perform fuzzification of these inputs into fuzzy inputs by using membership functions.
A membership function is a mapping between the universe of discourse (x-axis) and the grade space (y-axis). The universe of discourse is the range of possible values for the inputs or outputs. For ER_new % it is preferably from 0 to 100. Thevalue in the grade space typically ranges from 0 to 1 and is called a fuzzy input, truth value, or a degree of membership. FIG. 19 shows graph 300 which contains the membership functions for the input, Er_new %. Er_new % is divided into three linguisticvariables--LARGE (304), MEDIUM (306) AND SMALL (308). For Er_new %=60, the fuzzy inputs (or degree of membership function) are -0.25 of LARGE and 0.75 of MEDIUM. The input variable "Dir" is well defined (+ve, -ve or zero) and thus does not require amembership function in this application. The next step is to create the "Truth Table" or Rule Evaluation.
Rule Evaluation:
Rule evaluation takes the fuzzy inputs from the fuzzification step and the rules from the knowledge base and calculates fuzzy outputs. FIG. 20 shows the rules as truth table. For the first column and first row, the rule is: "IF ER_new % isLARGE AND Dir is NEGATIVE THEN New Gain is NO CHANGE (NC)" (i.e. if the percentage of e(t) data that is within the offset (OS) for last "tsum" seconds is LARGE and the direction (DIR) is NEGATIVE/ZERO then do not change the existing K value (NO CHANGE)).
In the example, because ER_new % has fuzzy inputs LARGE (0.25) AND MEDIUM (0.75) with POSITIVE Dir, the rules that will be used are: IF ER_new % is LARGE (0.25) AND Dir is POSITIVE THEN New Gain is NO CHANGE (NC=1) IF ER_new % is MEDIUM (0.75)AND Dir is POSITIVE THEN New Gain is POSITIVE SMALL CHANGE (PSC=1.2) Defuzzification:
Finally, the defuzzification process converts the fuzzy outputs from the rule evaluation step into the final output by using Graph 310 of FIG. 21. Graph 310, uses the following labels="NBC" for negative big change; "NSC" for negative smallchange; "NC" for no change; "PSC" for positive small change; and PBC for positive big change. The Center of Gravity or centroid method is used in the preferred embodiment for defuzzification. The output membership function for change in gain is shownin FIG. 21.
The centroid (the Fuzzy-Logic Output) is calculated as:
.times..times..mu..function..times..times..mu..function. ##EQU00001##
(x) is the fuzzy output value for universe of discourse value x. In our example, the output (K_new) becomes
.times..times..apprxeq. ##EQU00002##
Once the three steps of fuzzification, rule evaluation, and defuzzification are finished and the output has been calculated, the process is repeated again for new set of Er_new %.
In the above example, after the first 1000 sec, the adaptive algorithm calculates a new gain of K_new=11.50. This new gain is used for the next 1000 sec (i.e. from t=1000 to 2000 sec in real time) by the PID control loop. At t=1001 sec, counterEr_new is set to zero to perform counting for the next 1000 seconds. At the end of another 1000 seconds (ie. at t=2000 seconds), Er_new % is calculated again.
Suppose this time, Er_new % happens to be 25. This means, by changing K from 10 to 11.5, the control became worse. Therefore, it would be better to change gain in the other direction, i.e., decrease the gain rather than increase. Thus, att=2000 sec, Er_new %=25, Er_old %=60 (previous value of Er_new %), K_new=11.5 and K_old=10 (previous value of K). Applying Eq.(2), a negative "Dir" is obtained. With Er_new % of 25 and Dir=Negative, the fuzzy-logic calculation is performed again tocalculate a new gain for the next 1000 seconds. The new value of gain is K_new=7.76 and is used from t=2000 to 3000 seconds by the PID Loop.
Suppose for the third iteration, i.e., from t=2000 to 3000 seconds, Er_new % comes out to be 95% (which represents tighter control). Performing the same fuzzy-logic operation gives the same value of K_new, and the gain remains unchanged untilEr_new % again degrades.
Exemplary Applications:
Both pulse width modulated (PWM) Compressors and electronic stepper regulator (ESR) Valves can be used to control evaporator temperature/pressure or evaporator cooling fluid (air or water) temperature. The former controls by modulating therefrigerant flow and the latter restricts the suction side to control the flow. Referring back to FIG. 18, the block diagram of the control system for such an actuator working in a refrigeration system 279 is shown. In FIG. 18 one and preferably up tofour temperatures of evaporator cooling fluid or one evaporator suction pressure (generally shown at 282) is sampled every dt seconds. A sampling time of dt=10 seconds was found to be optimum for both the applications. After processing by the analog todigital module 284, the sampled signal is then reduced to one number by taking the average or the minimum or the maximum of the four temperatures depending on the system configuration or the user preference at module 286. Typically, in a single actuator(PWM/ESR) systems where the complete evaporator coil goes into defrost at one time, averaging of control signal is preferred. In a multiple evaporator-single actuator system where defrost of evaporator coils does not occur at the same time, minimum isthe preferred mode. The value obtained after avg/min/max is called conditioned signal. At comparison module 288 this is compared with the desired set point to calculate the error, e(t).
The control algorithm used in the loop is a Proportion-Integral (PI) control technique (PID). The Pi algorithm calculates the valve position (0-100%) in case of ESR or calculates the percentage loading (0 to 100%) in case of PWM compressor. Atypical integral reset time, Ti, for both the actuators is 60 seconds. The gain is tuned adaptively by the adaptive loop. The adaptive algorithm is turned off in the preferred embodiment whenever: the system is in defrost; is going through pull-down;there a big set point change; sensor failure has been detected; or any other system failure is detected.
Consequently, the adaptive algorithm is typically used when the system is working under normal mode. The time "ta" preferably used is about 1 seconds and "tsum" is about 1800 seconds (30 minutes).
Diagnostics Related to PWM Compressor/ESR Valves:
Referring to FIG. 22, a discharge cooling fluid temperature sensor 312 (Ta), an evaporator coil inlet temperature sensor 314 (Ti) and an evaporator coil exit temperature sensor 316 (To) can provide diagnostic features for the evaporator controlusing PWM/ESR. The Inlet temperature sensor 314 can be anywhere in evaporator coil 318. However, the preferred location is about one third of the total evaporator length from the evaporator coil distributor 320.
Using these three temperature sensors, system learning can be performed that can be used for diagnostics. For example, diagnostics can be performed for ESR/PWM when it is used in a single evaporator along with an expansion valve. In thisexample, the following variables are tracked every "tsum" second in the adaptive loop. The variables can be integrated just after ER_new integration is done in the adaptive loop. N-Close: Number of times Valve position/PWM loading was 0%. N-Open:Number of times Valve position/PWM loading was 100%. MAVP: The moving average of the Valve position/PWM loading for "tsum" seconds. SSLP: The steady-state Valve position/PWM loading is set equal to MAVP if for the "tsum" duration ER_new % is greaterthan 50%. dT: Moving average of the difference between Ta and Ti (Ta-Ti). SH: Moving average of the difference between To and Ti (To-Ti) in the said duration. This is approximately the evaporator superheat. N_FL: Number of times To was less than Tiduring the said duration, i.e., "tsum" seconds. This number will indicate how much the expansion valve is flooding the evaporator.
In addition, Pull-down time after defrost, tpd, is also learnt. Based on these variables, the following diagnostics are performed: temperature sensor failure; degraded expansion valve; degraded ESR valve/PWM Compressor; oversized ESR/PWM;undersized ESR/PWM; and no air flow.
Temperature Sensor Failure:
Failures of temperature sensors are detected by checking whether the temperature reading falls within the expected range. If PWM/ESR is controlled using Ta as the control variable, then when it fails, the control is done as follows. The abovesaid actuator is controlled based on Ti, or the Ta values are estimated using the learned dT (i.e., add dT to Ti value to estimate Ta). During pull down, the valve/PWM can be set to full-open/load for the learned pull-down time (tpd). If Ti also failsat the same time or is not available, the actuator is opened 100% during pull down time and then set to steady-state loading percent (SSLP) after pull-down-time. An alarm is sent to the supervisor upon such a condition.
Degraded Expansion Valve:
If an expansion valve sticks or is off-tuned or is undersized/oversized, the following combinations of the tracked variable can be used to diagnose such problems. N_FL>50% and ER_new %>10% indicate the expansion valve is stuck open or isoff-tuned or may be even oversized and thus is flooding the evaporator coil. An alarm is sent upon such a condition. Moreover, SH>20 and N_FL=0% indicate an off-tuned expansion valve or an undersized valve or the valve is stuck closed.
Degraded ESR Valve/PWM Compressor:
A degraded ESR is one that misses steps or is stuck. A degraded PWM Compressor is one whose solenoid is stuck closed or stuck open. These problems are detected in a configuration where defrost is performed by setting the ESR/PWM to 0%. Theproblem is detected as follows.
If ER_new %>50% before defrost and during defrost Ti<32.quadrature.F and SH>5.quadrature. F, then the valve is determined to be missing steps. Accordingly, the valve is closed by another 100% and if Ti and SH remain the same then thisis highly indicative that the valve is stuck.
If ER_new %=0 and N_Close is 100% and Ti<32 F and SH>5F then PWM/ESR is determined to be stuck open. If ER_new %=0 and N_Open is 100% and Ti>32 F and SH>5 F then PWM/ESR is determined to be stuck closed.
Over-Sized ESR/PWM:
If N_Close>90% and 30%<ER_new %<100%, then an alarm is sent for oversized valve/PWM Compressor.
Under-Sized ESR/PWM:
If N_Open>90% and ER_new %=0 and SH>5, then an alarm is sent for undersized valve/PWM Compressor.
No Air Flow:
If N_Open=100%, ER_new %=0, SH<5 F and Ti<25 F and N_FL>50%, then either the air is blocked or the fans are not working properly.
Additionally, these diagnostic strategies can also be applied to an electronic expansion valve controller.
The embodiments which have been set forth above were for the purpose of illustration and were not intended to limit the invention. It will be appreciated by those skilled in the art that various changes and modifications may be made to theembodiments discussed in this specification without departing from the spirit and scope of the invention as defined by the appended claims.
TABLE-US-00002 APPENDIX Pseudocode for performing signal conditioning Repeat the following every Ts Seconds: Read User Inputs: -Sampling Time (Ts) -Control Type (P or T) -Sensor Mode (Avg/Min/Max) Perform Analog to Digital Conversion (ADC) -onall (four) Temp. Sensor Channels output data as Counts Digitally Filter Counts -Ynew = 0.75 * Yold + 0.25 * Counts -output data as Filtered Counts Convert Filtered Counts to Deg F. Test if at least one Sensor is within normal operating limits -e.g.within -40 and +90F If none are within limit--Set Sensor Alarm to TRUE Else Perform Avg/Min/Max operation based on Sensor Mode If Control Type is NOT a T/P Control Type Then End Signal Conditioning Routine (until next Ts cycle) Else (Control Type is T/P)Do the Following: Perform ADC on Pressure Sensor Channel -output data as Counts Digitally Filter Counts -Ynew = 0.75 * Yold + 0.25 * Counts -output data as Filtered Counts Convert Filtered Counts to Psig Test if pressure Sensor is within normal operatinglimits -e.g. within 0 and +200 If not within limit: Set dP = dP Set Pt. Else: Calculate dP = Pmax-Pmin Set Sensor Alarm to Conditioned T/dP End Signal Conditioning Routine (until next Ts cycle)
* * * * *
Recently Added Patents
Post-processing device and image forming system
Biodiesel data collection system
Character input device and program for displaying next word candidates based on the candidates' usage history
Method for incubating the contents of a receptacle
System for controlled release of an active principle and method for preparation
Photomask blank, photomask blank manufacturing method, and photomask manufacturing method
Systems and methods for port mirroring with network-scoped connection-oriented sink
Randomly Featured Patents
Microprocessor assisted memory to memory move apparatus
Dishwashers and detergent dispensers
Polyamide dyeing process utilizing controlled anionic dye addition
Static pose fixture
Fuel injection control system with compensation for pressure and temperature effects on injector performance
2-Amino-3,4-dihydropyridines used to effect coronary vessel dilation and treat hypertension
Motorcycle security stand
Intraluminal device with improved tapered beams
Process for making and programming and operating a dual-bit multi-level ballistic flash memory
Carrying or storing devices, such as golf bags, having externally accessible storage systems
© 2006-2011. PatentGenius.com All Rights Reserved.


text:
Newly remodeled Davisson Hall East serves as home to OC's men in the Honors Program. Judge William Guy Davisson provided $500,000 in 1975 to construct the Davisson Residence Hall in memory of his wife, Reba.
- Predominantly honors students
- Community bathrooms
- Extra-long mattresses
- Shared and private rooms available
- Handicap-accessible room
- Public and private lobbies
- Kitchen with dining area
- Laundry room
- Study rooms
- Study carrels
- Conference Room
See Davisson Hall East Dorm Floor Plan

subset: commoncrawl


text:
My regular scheduled column about my 007 movie has been postponed so I can talk about something vastly more important.
My regular scheduled column about my 007 movie has been postponed so I can talk about something vastly more important.
I hear from a lot of people that they are tired of crime in the area. Thursday offers a rare chance for folks to put their money where their mouth is � by putting a fork full of barbecue in their yaps.
Thursday is Crime Stoppers annual barbecue plate fundraiser. Is 14 years long enough to be considered a tradition? I think so.
The event provides cash that will go directly to stopping crime.
I am a proud member of the Jacksonville-Onslow Crime Stoppers Board. And I can say unequivocally that 100 percent of all the money raised by the organization goes to halt local crime and lock up local criminals.
The program has rolled along thanks to sponsors like Marine Federal Credit Union, which has given large sums of money; National Dodge, which donated the Crime Stoppers car; and The Daily News, The Globe, Rotovue and Busted Locals, all of which have donated advertising space.
But all that only goes so far. The program needs not just the moral support from the community, but financial support as well.
�Our annual fundraising also relies heavily on outright donations from businesses, organizations and individuals, which has been negatively impacted over the last few years due to the economic downturn,� Crime Stoppers Chairman Joe Yannessa stated in a recent letter to the editor.
What he is saying is that Crime Stoppers in going to go broke if law-abiding citizens don�t start to chip in.
Joe won�t say it because he is a retired officer and forever a gentleman.
I�ve never been accused of either.
The program is kicking ass on the crime stopping side. Last year it had more tips and arrests than any other year. It is successful at helping police put bad guys behind bars. That keeps you safe. It keeps your children safe.
It�s also expensive. As I said before, 100 percent of the money raised by the program goes to pay rewards or promote the tip line. We don�t have rented space in a fancy office park. We don�t dine on lavish meals. Members pay for their own food at each meeting and we meet in available FREE public meeting rooms.
As the board has authorized major cash rewards for tips that assisted detectives in solving major crimes � murder, rape, armed robbery, child abuse, you name it � our resources have dwindled.
Simply, if not eloquently, put: Crime Stoppers needs you to contribute.
We are about stopping crime in our community. I am asking what you are about.
Stop by and buy a plate of food at a cost you would have eaten lunch for anyway that day and you will be helping to stop the next killer in our midst.
Get the whole office together and pre-order for everyone. Employers, treat your employees to some good food and help keep our city safe.
The barbecue is provided by Smithfields with hushpuppies cooked up by board member Sam Bright. If you�ve never had Sam�s hushpuppies then you�ve never had a hushpuppy. His are � bar none � the best hushpuppies ever made. Worth the $7 by themselves.
The grub will be waiting on the grounds of the Jacksonville Mall facing Western Boulevard on Thursday between 10 a.m. and 2 p.m. Pre-orders of five or more meals can be delivered to locations in Onslow County, including all military bases, and should be ordered by Tuesday by calling 910-346-6889 or 910-347-4007.
Tax-deductible donations to Crime Stoppers can be mailed to P.O. Drawer 436, Jacksonville, NC 28541. A receipt for all donations will be provided by return mail.
James Bond will return next week ...
Contact Daily News Senior Reporter Lindell Kay at 910-219-8455 or firstname.lastname@example.com. Follow him on Twitter and friend him on Facebook @ 1lindell.


text: Hi. I am trying to implement ISPConfig into website using Remote API. But I am really confused. There is a lot of ID's. What is difference between "userid", "client_id", "sys_userid" and "sys_groupid"? There is one more question. Function "client_get" returns array with the key "passwort", but function "client_get_by _username" returns array with the key "password". What is the difference between "passwort" and "password". It's the same thing?


text:
|555 East 14th Street surrounded by Community Park
Sarah Roseen
|(530) 757-5475
|Office Hours
|8am - 4pm M - F
|School PTA
|School Garden
|one of the Schools in the DJUSD
Their mascot is the dolphin. The Academic Index Performance (API) rose again from 903 to 908, making North Davis one of three elementary schools in Davis to score over 900 on this statewide measure. The state expectation is that each school reach 800. In addition to a strong academic program, students continue to enjoy rich visual and performing arts programs and a comprehensive P.E. program. Intermediate students will continue to participate in GEN YES, via a grant that brought laptop computers to their classrooms and the opportunity to learn in-depth technology skills that result in student-created multi-media presentations. This school welcomes parent volunteers in their classrooms, the computer lab, or the library.
North Davis Elementary School is the only school to have retained a name based on a compass direction in Davis.
Previous Principals
Sarah Roseen (Current)
Ramon Cusi, Ed. D (2008-2016)
Judy Davis (Boock) (1993-2007)
David Madrigal (1991-1993)
Mary Ellen Dolcini (ca 1985-1991)
Russ Whitzel (ca. 1957-1967)
You must be logged in to comment on this page. Please log in.
Go dolphins?! —StevenDaubert
2007-06-13 15:40:44 Off Topic....I love the bike trailer window photo. —RocksandDirt
Thanks! My daughter and I have made a game of the Photo Requests page: I ride around, she takes the shots. Wiki gets pictures of varying quality. We were in a rush for this one, otherwise I would have had her stand up. —KevinChin
2009-04-27 15:05:14 Hi there, I am interested in my soon to be first grader attending this school. Where in Davis do I need to live for her to attend? Does the performing arts extend even to the first graders, I mean do they really get them involved too? she would LOVE that. also I am interested in the demographics. At which Davis school would I be most likely to find Black/African American students and faculty? We are an international adoption family and it's important to me that she has positive relationships with other kids and/or faculty who "look like her." thanks for your help! —StephHolm
2009-07-09 21:26:38 My daughter attends North Davis CDC Preschool. We love the program. The director Cameron & her staff strive to make school fun & a positive learning environment. They offer 5 or 3 days and serve breakfast and a snack. My daughter has had no seperation anxiety at this school and we love it. —jwendt
2012-06-29 16:02:18 What happened to the arbors and trellises on the west (library) side of the school? They were graced for many years with flowering vines and lianas. I just stopped by the library and saw they've been totally hacked away. Whatever tree service did this went way overboard, and is obviously ignorant of proper maintenance and care of twining plants. (Maybe they did so to inflate their payment?) Now all that's left are industrial-looking metal frames (reminiscent of giant croquet wickets) painted a kind of camo-green that is scarred where the vines were ripped away. Seems like there could be better ways to spend schools' money than on such incompetent overkill work, especially when the school budget seems to be in such dire straits. The money spent on this hack job could have bought a few computers or quite a few books, am sure. RaoulDuke


text:
Kodo is Oracle's implementation of the Sun's Java Persistence API (JPA) and Java Data Objects (JDO) specifications for the transparent persistence of Java objects. The following documents help you develop, configure, and deploy Kodo applications.
Note:Oracle Kodo JPA/JDO is deprecated in this release. Customers are encouraged to consider using Oracle TopLink. For more information, see Oracle Fusion Middleware Developer's Guide for Oracle TopLink.


text:
Privacy Shades, Blinds & Window Treatments
- Opaque products to maintain privacy
- Routeless slats avoid light seepage
- Add a liner for increased opaqueness
- Layer coverings for light versatility
- Good for bed, bath & streetside rooms
Privacy blinds and shades are opaque, or non-transparent, enough to prevent view-through, even when backlit. Perfect for rooms facing the street or a neighbor, privacy shades or routeless blinds are perfect for keeping the inside of your home hidden. Some blind styles, such as woven woods, will require an added privacy liner to provide the extra opacity needed. We also recommend choosing a top down/bottom up lift option or layering your treatments, like a faux wood combined with drapery, to best balance your light control and privacy needs. While these products will block view-through, they will not necessarily block all light like our blackout shades.
1 results
Sort By:
Bali® DiamondCell® Cellular Shades: Light Filtering Double Cell
retail $91.04 $61.00 + an extra 20% off
Customizeback to products
Size24" x 36"
Your selections also include:
- Cellular / Honeycomb
- Double Cell
- 3/8" Pleat
- Cordless
- Cordless Top Down/Bottom Up
- Easy Cleaning
- Graber Comparable
- Hunter Douglas Comparable
- Remote Control / Motorized
- Cordless
- Top Down/Bottom Up
- Bali
- Top Seller
- Horizontal
- Beige / Neutral
- Blue
- Brown
- Gray
- Green
- Red / Pink
- White / Off-White
- Yellow / Cream
- Bathroom
- Bedroom
- Dining Room
- Family Room / Den
- Living Room
- Office
- Cellular
- Fabric
- French Doors
- Hard-to-Reach
- Sidelights
- Energy Efficient
- Child Safe
customer reviews for privacy
"Quality at a great price"
By Denice from California
Purchased Daybreak II - 3/8" Cell Butter Creme top down bottom up to replace expensive motorized Hunter Douglas cellulars that kept malfunctioning. No regrets.View this product
"Great service and blinds"
By from
Fast response to sample request. Rapid and useful response to customer questions. Excellent instructions. Quality of product and fit is excellent. Bravo!View this product


text:
As officials from the city of Shawnee and Pottawatomie County continue talks toward a possible merger of the two 911 centers to better serve all residents, they agree that a tour of Muskogee's successful 911 center earlier week was "impressive."
As officials from the city of Shawnee and Pottawatomie County continue talks toward a possible merger of the two 911 centers to better serve all residents, they agree that a tour of Muskogee's successful 911 center earlier week was "impressive."
An informal committee that has been talking about ways to consolidate the two local centers, with efforts intensifying in recent months, made plans in February to tour other counties that have had successful mergers of 911 centers.
Thursday, a group traveled to Muskogee to see the results there after five smaller 911 centers merged into one under the direction of a trust board.
Shawnee Mayor Wes Mainord said the tour was very informative.
"They put the county and city together in a merger like we are discussing," the mayor said, adding the were able to see how it was set up "with electronics everywhere."
"It's very sophisticated," Mainord said, adding the costs of running the one center there are divided between the city and county.
"It was kind of exciting to see," the mayor added.
Mainord, who said Muskogee has shared their trust documents and interlocal agreements, still feels consolidation is a good idea, but admits it may take some time.
"It may take a while to get these ducks in a row," Mainord said.
Pottawatomie County Commissioner Melissa Dennis, who said the population of Muskogee County is very similar to Pottawatomie County, said the visit went well.
"They told us how it went from the beginning stages to where they're at," Dennis said, adding they all listened, learned and asked a lot of questions.
Seeing the 911 center in full operation was a key part of the tour.
"It was inspiring to me," Dennis said. "They make it look so easy."
But Dennis said there were a lot of logistics involved in getting that center up and running.
"It took them a year to get everything ready and going before they could flip the switch and open the center."
Shawnee Police Chief Russell Frantz, who oversees the city of Shawnee 911 center, said he was impressed in the oversight of Muskogee's 911 center, which is a governance board made up by the actual stakeholders of the system, such as police chief, fire chief and other leaders in that county's public safety system.
"I liked how their governance board was made up by users of the system," he said. Frantz also was impressed with the systems in place.
"Shawnee Police Department technology matches their technology and they're doing the same stuff we're doing," Frantz said. "Our dispatch has the same capabilities."
Frantz, who said the city of Shawnee has about a $630,000 annual budget for its 911 center and Pottawatomie County's budget is about $710,000, said the Muskogee Center is run on a $2.1 million budget with costs split between the city and county there.
Through hearing how the center came to be in Muskogee, Frantz said they learned the first six months was tough, but there are many similarities. Frantz said he discovered the dispatch room there is about the same size as an area of city hall that he has proposed for use as a merged 911 center here in Shawnee.
Muskogee also has about six dispatchers on duty for each shift, he said, which is very comparable to what is done locally with three on duty at Shawnee and two to three at the county center, proving his theory that all job positions from the two centers would be needed even with a local merger.
"We're not saving money people wise," the chief said, but rather facility wise by not operating two different centers.
Pottawatomie County Sheriff Mike Booth, who serves as a board member of the County's E-911 trust board, said the trip was very beneficial in giving them a direction to go from here.
"In my opinion, we're further along than they were they they first started," Booth said, adding they can learn a lot from others as they go through this process.
"Why reinvent the wheel — we can learn from what they've done," Booth said. 'They've got a lot of good ideas."
Judy Chance, also a member of the county 911 board, said they saw a lot of good things about Muskogee's successful center.
"The tour of the center was amazing," she said. "The folks at Muskogee are very knowledgeable and have experienced much of what we have been going through here in Shawnee."
Chance said they learned the key their merger was an interlocal agreement as well as the formation of a trust with representation of all entities, with employees being trust employees and the city and county splitting the costs of the center equally.
And while local officials still plan to conduct tours of other 911 centers, possibly in Lawton and Elk City, Frantz said he still believes an outside consultant previously discussed is a good idea as they continue toward consolidation.
With the city of Shawnee having $8 to $10 million in assets toward a merger, Frantz said he feels it's a good idea to have an outside set of eyes to look at and advise officials through the process.
"We want to make sure we get this thing right from the beginning," Frantz said.
The city of Shawnee currently operates its communication center to dispatch Shawnee police, fire and REACT ambulance calls, while Pottawatomie County 911 has its service operating out of Tecumseh. The county 911 center dispatches for Tecumseh, county fire departments, REACT as well as the sheriff's office and some tribal departments.
Watch for updates.


text:
It is possible that the main title of the report Trichorhinophalangeal Syndrome Type II is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.
Trichorhinophalangeal syndrome type II (TRPS2), also known as Langer-Giedion syndrome, is an extremely rare inherited multisystem disorder. TRPS2 is characterized by fine, thin hair; unusual facial features; progressive growth retardation resulting in short stature (dwarfism); abnormally short fingers and toes (brachydactyly); "cone-shaped" formation of the "growing ends" of certain bones (epiphyseal coning); and/or development of multiple bony growths (exostoses) projecting outward from the surfaces of various bones of the body. In addition, affected individuals may exhibit unusually flexible (hyperextensible) joints, diminished muscle tone (hypotonia), excess folds of skin (redundant skin), and/or discolored elevated spots on the skin (maculopapular nevi). Affected individuals may also exhibit mild to severe mental retardation, hearing loss (sensorineural deafness), and/or delayed speech development. The range and severity of symptoms varies greatly from case to case. TRPS2 is due to the absence of genetic material (chromosomal deletions) on chromosome 8. The size of the deletion varies from case to case.
March of Dimes Birth Defects Foundation
1275 Mamaroneck Avenue
White Plains, NY 10605
Tel: (914)997-4488
Fax: (914)997-4763
Tel: (888)663-4637
Email: email@example.com
Internet: http://www.marchofdimes.com
Little People of America, Inc.
250 El Camino Real
Suite 201
Tustin, CA 92780
Tel: (714)368-3689
Fax: (714)368-3367
Tel: (888)572-2001
Email: firstname.lastname@example.com
NIH/NationaI Institute of Arthritis and Musculoskeletal and Skin Diseases
Information Clearinghouse
One AMS Circle
Bethesda, MD 20892-3675
Tel: (301)495-4484
Fax: (301)718-6366
Tel: (877)226-4267
Email: email@example.com
Internet: http://www.niams.nih.gov/
NIH/National Institute on Deafness and Other Communication Disorders
31 Center Drive, MSC 2320
Communication Avenue. Bethesda, MD 20892-3456
Tel: (301)402-0900
Fax: (301)907-8830
Tel: (800)241-1044
Email: firstname.lastname@example.com
Internet: http://www.nidcd.nih.gov
Coalition for Heritable Disorders of Connective Tissue
4301 Connecticut Avenue, NW, Suite 404
Washington, DC 20008
Tel: (202)362-9599
Fax: (202)966-8553
Tel: (800)778-7171
Email: firstname.lastname@example.com
Internet: http://www.chdct.org
MUMS National Parent-to-Parent Network
150 Custer Court
Green Bay, WI 54301-1243
Tel: (920)336-5333
Fax: (920)339-0995
Tel: (877)336-5333
Email: email@example.com
Internet: http://www.netnet.net/mums/
Genetic and Rare Diseases (GARD) Information Center
PO Box 8126
Gaithersburg, MD 20898-8126
Tel: (301)251-4925
Fax: (301)251-4911
Tel: (888)205-2311
Email: http://rarediseases.info.nih.gov/GARD/EmailForm.aspx
Internet: http://rarediseases.info.nih.gov/GARD
Madisons Foundation
PO Box 241956
Los Angeles, CA 90024
Tel: (310)264-0826
Fax: (310)264-4766
Email: firstname.lastname@example.com
Internet: http://www.madisonsfoundation.org
Trichorhinophalangeal Syndrome Association
6585 Dawn Way East
Inver Grove Heights, MN 55076
Tel: (651)450-0788
Email: firstname.lastname@example.com
Internet: http://trpsa.org/trpsa_wp/
This is an abstract of a report from the National Organization for Rare Disorders, Inc. ® (NORD). A copy of the complete report can be obtained for a small fee by visiting the NORD website. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational treatments (if available), and references from medical literature. For a full-text version of this topic, see http://www.rarediseases.org/search/rdblist.html
The information provided in this report is not intended for diagnostic purposes. It is provided for informational purposes only. NORD recommends that affected individuals seek the advice or counsel of their own personal physicians.
It is possible that the title of this topic is not the name you selected. Please check the Synonyms listing to find the alternate name(s) and Disorder Subdivision(s) covered by this report
This disease entry is based upon medical information available through the date at the end of the topic. Since NORD's resources are limited, it is not possible to keep every entry in the Rare Disease Database completely current and accurate. Please check with the agencies listed in the Resources section for the most current information about this disorder.
For additional information and assistance about rare disorders, please contact the National Organization for Rare Disorders at P.O. Box 1968, Danbury, CT 06813-1968; phone (203) 744-0100; web site www.rarediseases.org or email email@example.com
Last Updated: 5/25/2008
Copyright 1996, 1997, 1998, 2005 National Organization for Rare Disorders, Inc.
This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information.


text: Hello internet world! My name is Marion Bachman and I'm thrilled to be joining the team as a Traffic School, Defensive Driving and Teen Education curriculum consultant with Myimprov.com. To me, driving and urban transportation aren't simply a means of getting from one point to another, they're the backbone of commerce that propels our country into the future. My goal is to bring interesting, informative and thought-provoking articles and news about driving as it relates to traffic and driving on America's roadways. First though, here's a bit about me personally and why I'm such a "traffic geek."... Read More


text:
Top 10 Items that Should Be Listed in an IEP
April 10, 2014 in Special Education Advisor Blog by Dennise Goldberg
We all know how important it is to have an IEP that addresses our child's Academic, Developmental and Functional needs; to ensure they are appropriately prepared for an independent future. Therefore, as parents, we have to make sure our child's IEP includes the necessary information to prepare them for life after high school. The results of your child's most recent assessments, report cards, state tests, school personnel and parent input will assist the team in developing an appropriate IEP. Read the rest of this entry →


text:
Please select your meditation time
Start Meditating
Conclude Meditation
Lent Daily Reflections by Fr. Laurence Freeman, year 2011
Many religions predict some kind of final judgment. For the ancient Egyptians it involved a confession by the dead person of their faults and then the weighing of the heart on a great scale against the "feather of maat".
Maat was the principle of truth and justice. If the heart was too heavy with unconfessed sin and weighed more than the feather, the punishment was not pain but de-creation. For the Egyptians, the idea of non-existence was worse than that of hell.
Life presents different faces of reality to us in an always unpredictable sequence. Getting on a bus or deciding to move to a new apartment may be trivial events of forgettable meaning, or they may become milestones of our life because of the consequences they bring.
Another praxis of Lent, indeed of a gospel lifestyle, is almsgiving. This is usually associated with giving money to good causes but it is only part of its meaning. As Jesus illustrated by his reaction to the poor woman who gave her mite in the temple – she gave more than the rich because she gave with more generosity than them – the spiritual significance of giving is not defined by the number of zeros. To give a little quantitatively may be to give everything spiritually.
Religion without praxis is hypocrisy. In Greek this word means what is done by the free. It is putting theory and good intentions into reality. Spiritually it means living on the level of experience. In praxis we embark on a process rather than just shooting for a goal. We are therefore also accepting and working with our imperfections – because, however good our praxis may be, we are not aiming at our own perfection. This would be to fall right into the trap of the ego.
Realizing you have really lost something sends a shock through your whole system, a pang of grief mixed with anger and confusion. It might be your car keys or someone you love; the intensity and duration of the shock will be different but the immediate resistance to losing what we (think) we possess is built into our psyche.
Today you may see people on the bus or subway or waiting by the photocopier with a dirty mark on their forehead. Like seeing someone meditate in an airport terminal or waiting room you recognize them as fellow travelers on a spiritual journey, not mere strangers passing in the night. It is not a secret sign or an exclusive club but few they are who understand it.
We receive the ashes as a reminder not to waste time. "Remember you are dust and unto dust you will return. Repent and believe the good news".


text:
QuiltCon, the inaugural modern quilting show, took place in Austin this past weekend. Moda Fabrics and the Moda Bake Shop had a booth, and it was wonderful to meet so many Bake Shop readers in person. If you took photos in our photo booth, we'd love to see them! Add them to our Flickr group.
If you are looking for a pattern for one of the quilts on display in the booth, here is the full list with links:
Cindy Sharp | Nough Said Layer Cake Quilt
Natalia Bonner | Skittles Quilt
Jessica Kelly | Simply Woven Quilt
Elizabeth Dackson | Modern Halves
Erica Jackman | Cozy Posy Triangle Quilt
Tammie Schaffer | Charm Crossing Quilt
Amanda Castor | Pezzy Lattice Quilt
Ali Winston | Charming Plaid Quilt
Lissa Alexander | Honeycomb Quilt
Oda May
Pre-cut Guru at Moda Fabrics/United Notions
The Moda Bake Shop is a division of Moda Fabrics that provides online recipes which you can use with the wide range of Moda Pre-cuts. All sizes and types of projects will be featured from various designers and shops. Tutorials for various Moda projects sheets will be illustrated with step by step pictures. Some techniques and products will also be featured throughout, so check back often for what is "baking" here at Moda Fabrics.
Latest posts by Oda May (see all)
- Building Blocks: 4-Patches - September 26, 2018
- National Sew a Jelly Roll Day - September 15, 2018
- How to Make: Continuous Bias Binding - September 2, 2018


text:
Does Robin Thicke's "Blurred Lines" sound too much like one of its disco-funk ancestors?
No way, says Pharrell Williams, who co-wrote and produced the Thicke hit.
Though it recently finished a 12-week run atop Billboard's Hot 100, "Blurred Lines" has created plenty of controversy with its racy music video and lyrics that some observers have called "rapey."
It's also under fire from listeners who say the song rips off "Got to Give It Up," the 1977 R&B jam by Marvin Gaye that, like "Blurred Lines," prominently features a slinky bass line and the clang of a cowbell.
Not surprisingly, perhaps, Thicke disagrees.
Last month, he, Pharrell and the song's other creator, rapper T.I., filed a lawsuit asking a judge to determine that their song doesn't copy "Got to Give It Up."
"It was a preemptive strike against future claims from Gaye's heirs that the song takes from Gaye's composition without credit," according to the Associated Press.
Now Pharrell has spoken about the perceived similarities between the two tracks.
"If you read music, all you have to do is read the sheet music," he told the AP in an interview Thursday night. "It's completely different."
Gaye, he went on, "is the king of all kings, so let's be clear about that." (Pharrell also called the late R&B star "a genius" and "the patriarch.") "And we take our hats off to him.
"But anybody that plays music and reads music, just simply go to the piano and play the two. One's minor and one's major. And not even in the same key."