Showing papers on "Process variable published in 1968"
01 Jan 1968
TL;DR: The final author version and the galley proof are versions of the publication after peer review and the final published version features the final layout of the paper including the volume, issue and page numbers.
Abstract: • A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers.
21 citations
Patent•
24 Oct 1968TL;DR: In this paper, an industrial process is subject to a number of uncontrolled variables and an analogue or digital computer derives, from measurements 16, a signal representing process performance which is to be maximized or minimized Signals having amplitudes corresponding to the performance signal, but polarities opposite to each other, are produced at 30 and respectively applied to MOSFET gates 73, 74 which are opened by pulses from a clock 43 so that performance signal pulse trains of opposite polarity are alternately applied through a further clock-controlled MOSfET gate 80 to an amplifier 83 rendered integrating by
Abstract: 1285973 Adaptive control WESTINGHOUSE ELECTRIC CORP 2 Oct 1969 [24 Oct 1968] 48440/69 Heading G3R Signals of opposite polarity dependent on a function of a variable of a perturbated process are alternately applied at intervals through MOSFET gates, an integrator and a memory to maintain the variable at a maximum or minimum In Fig2, an industrial process 10 is subject to a number of uncontrolled variables 11 and an analogue or digital computer 17 derives, from measurements 16, a signal 18 representing process performance which is to be maximized or minimized Signals having amplitudes corresponding to the performance signal, but polarities opposite to each other, are produced at 30 and respectively applied to MOSFET gates 73, 74 which are opened by pulses from a clock 43 so that performance signal pulse trains of opposite polarity are alternately applied through a further clock-controlled MOSFET gate 80 to an amplifier 83 rendered integrating by a feedback condenser 82 Synchronously with the alternate operation of gates 73, 74, clock 43 applies an output 42 to produce, through a control element 14, alternate increase and decrease in the value of one variable of the process If the performance signals corresponding to increase and decrease are of different magnitudes, indicating that performance is not a maximum or minimum, integrator 83 produces a resultant signal which, at the end of a period determined by a clock signal on line 70 operating a MOSFET gate 120, is transferred to a capacitor type memory 122 to adjust the process variable through an amplifier 39 in such a sense as to improve performance The performance signals from computer 17 are also applied through similar optimizing controllers 33, 35 to control other variables of the process A high input impedance of integrating amplifier 83 is obtained by a dual input through inter-connected MOSFETS 84, 85 and guard potential plates to minimize leakage arranged in the vicinity of the terminals of integrating resistor 81 Similar safeguards are provided for the input circuit of amplifier 39 A process variable may be manually adjusted in one sense or the other by appropriate operation of two-way switches 141, 145 Bumpless transfer of control between systems is referred to
2 citations
01 Aug 1968
TL;DR: In this paper, the authors propose to use the field effect transistor (f.e.t.) as a variable resistor whose value is controlled by the gate potential to form two ratio arms of a bridge.
Abstract: The field-effect transistor (f.e.t.) can be utilised as a variable resistor whose value is controlled by the gate potential. This relationship is inherently nonlinear, but good linearity can be achieved if two are used together as a potential divider to form two ratio arms of a bridge. This feature opens the way to the design of bridge-type instruments which can convert the ratio of two resistances, inductances or capacitances into a proportional d.c. signal. The principle is embodied in a 4–20 mA 2-wire process transmitter in which the process variable is arranged to unbalance such a bridge. Out of balance is detected by an a.c. amplifier, whose output is demodulated to control the transmission current and the gate potentials of the two f.e.t.s to re-establish bridge balance, thus providing a truly self-balancing system. Solid-state circuitry is used throughout, and operation over an ambient temperature range of −30°C to +80°C with very low temperature coefficient is obtained by suitable compensation of the f.e.t. potential divider.