Showing papers on "Process variable published in 1984"

Discontinuous optimization procedure modelling the run-idle status of plural process components

Abstract: A method of optimizing the operation of a process so that desired products are produced at minimum cost. The process has a plurality of process components, with each component having a run status and an idle status. The process has available more than one input and produces more than one output. The process is controlled by a computer which is provided with a mathematical model of the process, which model includes a model of each of its components. The model for each process component includes a logic variable, which logic variable can have only two values, 0 and 1, and which represent the run or idle status of each process component. The computer, when predetermined conditions arise, solves a mixed integer equation to determine the optimum state of the process at a given time to produce the desired outputs, at desired rates and at minimum cost; and, in doing so, determines the value of the logic variable for each component. When a change of status of a process component from run to idle or idle to run is required to place the process in its optimum state, control signals to cause such change of status of process components are applied to such components.

Time-discrete adaptive switching on-off-controller

Abstract: The present invention relates to an arrangement for the discrete-time adaptive on-off switching control of a continuous-time process with a binary switching actuator, which uses for the determination of the on-off actuating signal a prediction of a process output sequence over several future sampling intervals as reaction to a possible process input sequence that is applied to a discrete-time linear process model and which estimates and updates in every sampling interval the parameters of the process model by means of a parameter estimation device in order to adapt them to the process to be controlled, even when the process behavior changes, and which has a device for the input and change of the setpoint, the limits of the process output and the sampling time as well as a measuring device for the periodical measurement of the process input. The arrangement further comprises two alternatively working control devices one of which is active in the stationary phase and the other of which is active in the start-up phase of the process or after setpoint changes, and a switching device which activates one or the other said control device in dependence of the result of the measurement of the process output and of input current setpoint, wherein the actuator is served by the active control device.

Process control apparatus with process dependent switching between process control modes

Abstract: The process control apparatus according to the present invention is adapted to control the process automatically in compliance with the state of the process characteristics. In the process control apparatus, when the process characteristics are found to be in a steady state, the control is performed by a first process control operational means suited for sample controlling the process according to the control constants for the first process control operational means as determined during the control of a second process control operational means, while, when the process characteristics vary frequently, the control is performed by the second process control operational means which is suited from sample controlling the process.

Chemical process monitor

Abstract: A chemical process monitoring system wherein both a chemical process parameter control means (e.g. standard water treatment controller) and the means for adjusting the controlled process parameter (e.g. chemical feed pump) are simultaneously monitored through an interrogation means (e.g. microprocessor to determine if the adjusting means is successfully responding to the control means; and, if not, an alarm signal is generated to the operator.

Process control system

Abstract: PURPOSE:To perform a control adapted to a change of a process variable of a substance by holding a program so that the difference between the process variable of the substance and another process variable concerning this process variable does not exceed a certain range. CONSTITUTION:A program process controller PPC7 compares a preliminarily set program set value SP0 with the output value of a sensor 5 indicating the temperature of a substance 2 and sends a set signal proportional to the difference to a cascade controller 8. The controller 8 supplies an operation signal, which determines a manipulated variable, to an operator 4 on a basis of the difference between the value of the set signal from the PPC7 and the output value of a sensor 6 indicating the temperature of a thermal medium 3. If the deviation between the program set value SP0 and the output value of the sensor 5 exceeds a set range, the PPC7 holds temporarily the advance of a preliminarily set program and keeps this state until said deviation enters into the set range again. In this holding time, the operation signal from the cascade controller 8 is changed in accordance with only the variance of temperature of the thermal medium 3.

CASTAM: A process variation analysis simulator for MOS LSI's

Abstract: A simulator named CASTAM, which includes both process and device models, has been developed to predict MOS process variations through the analysis of variations in electrical characteristics of fabricated MOS devices using the Monte Carlo method. Analysis accuracy using the simulator is examined. Investigation shows that process parameter variations can be estimated with an error of less than 10 percent if an appropriate set of device characteristic items is chosen. Wafer inspection data for a CMOS pilot line can be analyzed with this simulator, and the main cause of threshold voltage variation pinpointed. Predictions derived from the analyzed results have been confirmed using experimental data. This shows that analysis using CASTAM is sufficiently reliable.

Temperature controller for industrial furnace

Abstract: PURPOSE:To attain the temperature control of an industrial furnace with high stability and high responsiveness by approximating the dynamic characteristics of the furnace temperature with a prescribed transmission function and obtaining the parameter of said function to calculate the optimum control parameter. CONSTITUTION:A material 2 such as a steel stock, etc. is shifted within a continuous heating furnace 1 while it is heated by a burner 5. A tracking arithmetic device 6 traces the state of a heating zone Z at and after a time point when the material 2 is put into the furnace 1 and calculates the position, etc. of the material 2 from its moving state. While a temperature arithmetic device 7 calculates the surface temperature of each material from the result of the device 6 and the furnace temperature obtained from a thermometer 3. Then a process characteristic arithmetic device 8 calculates the parameter related to the transmission function of the process from the results of both devices 6 and 7 as well as the furnace temperature. Furthermore a control parameter arithmetic device 9 calculates the optimum PID parameter against said transmission function and gives it to a controller 4. Then the fuel amount supplied via a route 10 and the burner 5 is controlled to obtain the coincidence between the PID parameter and the target value.