Computer-controlled tuning

In the present study, we propose a tuning method for PID controllers and apply the method to control the PBL process in LG chemicals Co. located in Yeochun. In the tuning method proposed in the present work, we first find the approximated process model after each batch by a closed-loop Identification method using operating data and then compute optimum tuning parameters of PID controllers based on GA (Genetic Algorithm) method. 

The precise measurement frequency varies slightly with solvent, temperature, concentration, sample volume and solute or solvent polarity, so that exact adjustment must be carried out before each measurement. This process, known as tuning and matching, involves variation of the capacity of the circuit. Modern spectrometers carry out such processes under computer control. 

In order to use the stopped-flow technique, the reaction under study must have a convenient absorbance or fluorescence that can be measured spectrophotometri-cally. Another method, called rapid quench or quench-flow, operates for enzymatic systems having no component (reactant or product) that can be spectrally monitored in real time. The quench-flow is a very finely tuned, computer-controlled machine that is designed to mix enzyme and reactants very rapidly to start the enzymatic reaction, and then quench it after a defined time. The time course of the reaction can then be analyzed by electrophoretic methods. The reaction time currently ranges from about 5 ms to several seconds. 

This is an important area that has to be thoroughly analyzed and studied to obtain the desired performance of the complete line and/or its parts such as the injection mold, extruder puller, and so on. The first task is to determine what is required and how to approach any potential problem. Adequate PC and its associated instrumentation are essential for product control. Sometimes the goal is precise adherence to a control point, other times it is sufficient to maintain a control within a comparatively narrow range. For effortless controller tuning and lowest initial and operating cost, the processor should select the simplest controller (temperature, time, pressure, flow rate, etc. that will produce the desired results. For the complete line, they can range from unsophisticated to extremely sophisticated devices that interrelate information. As an example there is the computer Hosokawa Alpine... 

The control computer/DCS system consists of controllers, A/D and D/A converters, and the signal conditioifing hardware and software, i.e., filtering and validation. Each of these components requires separate evaluation. Table 15.5 lists possible problems with the controller/DCS system. One way to initially check controller tuning is to place the control loop in manual (open the control loop) and observe whether the controlled variable lines out to a steady-state or near steady-state value. Comparing the open-loop and closed-loop performance indicates whether the controller is upsetting the process. If not, disturbances to the control loop in question are the primary source of the upsets. 

A recent flurry of activity in aberration correetion has been partially prompted by the ease of reliable precision lens control offered by the personal computer and the computer-aided tuning of complex lens systems. Several demonstration models have been developed for TEM [3.44], SEM [3.45] and STEM [3.46] that illustrate the general validity of the eoneept. The application of spherical aberration correctors is most effective in dedieated STEM because it suffers less from chromatic aberration due to a lack of post-specimen lenses (for example for high-angle annular dark-field imaging). 

Does the design of a control loop change when we use digital computer control What about the stability conditions and the tuning of a loop ... 

The first TiiSapphire lasers needed some fine-tuning to obtain stable pulses, especially when the wavelength was changed. The pulse stability had to be checked by a photodiode and the pulse width by an autocorrelator. For the past few years, computer controlled self-adjusting Ti Sapphire lasers have been available. These lasers do not need manual alignment. 

Computers are integral components of all modem mass spectrometer systems where they have two major functions instrument control (including data acquisition) and data handling. Dedicated computers control most instrument operation functions, ranging from relatively simple parameters, such as tuning and calibration, to more complex decision-making processes required during data acquisition. 

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