Data Acquisition Systems DAS

Data acquisition systems are extremely useful in extrusion because problems often occur when the operator is not watching the instrument panel of the extruder. Even if the operator is watching the instrument panel, he can only observe a limited number of variables at one time. A DAS that captures and saves important process data is indispensable in troubleshooting. When a problem occurs at 2 30 AM, it is very difficult for a process engineer coming in at 7 00 AM to reconstruct the events at 2 30 AM if important process data was not recorded at that particular time. 

A simple DAS is a chart recorder that can track important variables like screw speed, diehead pressure, melt temperature, motor amperage, etc. More useful is a computer-based DAS these come in two forms portable data collectors/machine analyzers and fixed-station data acquisition system. 

Portable data collectors, PDCs, are similar to check sheets in that they can be easily moved around. In injection molding, these devices are often referred to as portable machine analyzers, PMAs. They have some important advantages  

PMAs can collect variables as well as attributes data. The use of PMAs has increased considerably as the prices have come down to levels that are affordable even for small operations [162], Several PMAs are presently available for less than 10,000. 

Most PMAs offer the user some flexibility in assigning inputs to the data acquisition channels this even extends to auxiliary equipment, e.g., dryers, and external signals, such as plant ambient temperature and relative humidity. Important inputs are  

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Here F filters a suspension and produces a clear filtrate as well as a concentrated suspension which is pumped into and out of reservoir RZ. During the process a fraction of the concentrated suspension is eliminated. In order to have a continuous process it is advisable to have working state values close to steady state values. The exit or output control variables (D and CD registered) are connected to a data acquisition system (DAS), which gives the computer (PC) the values of the filtrate flow rate and of the solid concentration for the suspension transported. 

The power supply to the electrolyser was a Model 710 from The Electrosynthesis Company, Inc. of Lancaster NY. It was operated in constant current mode rather than in constant voltage mode. The maximum current and maximum voltage available was 50 amperes and 20 volts, respectively. In addition to current measurement provided by the power supply, a calibrated shunt was connected to the output to allow for independent measurement of current. Voltage taps independently connected to the cell electrodes were connected to the data acquisition system (DAS). The instrument signals from thermocouples, pressure gages, and flowmeters were connected to the DAS, which was comprised of a Dell computer with special acquisition boards and Labview software. Observations and some data were manually recorded in a laboratory notebook. 

Figure 1A is a schematic of the temperature measurement and control circuit. A type T thermocouple (see Note 2), inserted in a glass capillary, measures the temperature of a capillary with similar characteristics to capillaries holding the reaction mixture. The thermocouple is connected to an A/D channel of the data acquisition system (DAS) in a differential configuration (rrrNote 3). The DAS system is also used to communicate output commands (D/A channels) from the computer to the thermocycler. The DAS system employed in this study has eight channels available that can be used as either inputs or outputs. The fans and the heater are connected to the output channels of the board via solid state relays. 

With regard to the data acquisition system (DAS), there are two main problems concerning the A/D conversion and the triggering. Fast A/D units have to be used to ensure that a large number of events are recorded -usually there are A/D converters for each channel of the recording unit. Anti-aliasing (low pass) filters are required so that the signal can be properly transformed to the frequency domain by means of Shannon s Theorem (Rikitake et al. 1987). 

Electronic data acquisition systems (DAS) allow real-time monitoring of all process variables and pertinent product dimensions... 

Fuel cell circuit for current interrupt test consisting of load, on/off switch, and a transient recording device such as oscilloscope of data acquisition system (DAS). 

With the exception of the data acquisition system (DAS), the MACE test apparatus is housed within an explosion-rated containment cell used for a (dismantled) research reactor. The containment cell provides convenient radiological control as well as protection from postulated end-of-spectrum steam explosion and hydrogen behavior effects. 

Figure 3. Flow sheet of a computerized combination gas chromatograph ((X) and mass spectrometer (MS) DAS = data acquisition system, s separator, i = interface, d.r. = data reduction...

Fig. 4-1. Batch apparatus for study of ion-exchange kinetics A) Kressman-Kitchener stirrer-reactor, and B) automated system for kinetic monitoring where M = stirrer UT = ultrathermostat RE = stirrer-reactor E = potentiometer R = recorder DAS = data acquisition system C = computer P = plotter EL = electrodes b = baffles T = thermometer and PA = pneumatic pump (from Petruzzelli and Palmisano, 1981).

As the name implies, fixed station data acquisition systems are fixed to one location, either because of size or because the wiring makes it very difficult to move the unit. A fixed station DAS can have a wide range of capabilities. A simple DAS may record data from only one extruder, i. e., a dedicated DAS. A number of machine suppliers now offer extruders with integrated data acquisition and SPC capability. 

DAIP diallyl isophthalate DAP diallyl phthalate DAS data acquisition system dB decibel DC direct current den denier... 

Tensile tests at low to intermediate displacement rates (i.e. 1, 10, 100 and 500 mm/min) were performed by an Instron tensile tester model 4502 equipped with a 1 kN load cell. Temperature in the range from 0°C to 70°C was controlled by an Instron thermostatic chamber model 3119. Tests at the moderately high displacement rate of 60000 mm/min (1 m/s) were carried out at room temperature by an instrumented CEAST impact pendulum in the tensile configuration. Load data were collected at a sampling time of 30 p.s and load vs displacement curves were provided directly by the CEAST software (DAS 4000 Extended Win Acquisition System Ver. 3.30). 

All measurements were carried out on the Bruker Daltronik Apex II 4.7 ESI/ MALDI/Fourier-Transform-Ioncyclotron Mass Spectrometer. The number of data points per measurement was 256 K in the mass range 100-1500 Da.The range was scanned one time per second and 16 scans were accumulated. The time shifted start of the automated measurements was possible by transfer of a TTL pulse of the FIPLC system to the acquisition computer of the mass spectrometer at the time point of injection of the autosampler. 

More complex mixtures can be analyzed in a similar way providing that there are no deviations from Beer s law. Derivative spectrophotometry can also be used to mathematically process the data after acquisition in order to improve spectral resolution in multi-component systems. In this approach the zero-order spectrum is derivatized to give first order (dA/dA) or higher plots of the rate of change of absorbance against absorbance. 

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