Showing papers on "Process variable published in 1982"

Monitoring cure viscosity of epoxy composite

Abstract: Viscosity is an important process variable that should be monitored and controlled to ensure the consistent and reliable production of graphite-fiber-reinforced composite parts by the autoclave/vacuum bag process. Unfortunately, no technique is currently known for the direct measurement of viscosity in this process. However, d.c. conductivity and a.c. phase lag appear to correlate quite well with viscosity, and either electrical property may be followed in order to indirectly monitor viscosity. As the method of measuring d.c. conductivity is so inexpensive, simple, and almost free of electrical interference compared to the method of measuring a.c. phase lag, it appears to be the method of first choice for application in an autoclave environment.

Adaptive process control using function blocks

Abstract: An adaptive control for a process is disclosed which utilizes a process parameter calculator made up of simple function blocks which generate a plurality of process parameters, and a tuning parameter calculator, also made up of simple function blocks, for calculating tuning parameters from the process parameters. The process parameter calculator is provided with values for various disturbances, a set point, a control output from a process controller and process structure data including process sensitivity and nominal operating data. From these values, the process parameters are determined. The tuning parameter calculator is provided in addition to the process parameters, with performance parameters and design function for generating tuning parameters that are applied to the controller for modifying the control output in response thereto.

Process variable transmitter

Abstract: A process variable transmitter including a plurality of process variable detector units for detecting a primary process variable to be measured and secondary process variables not to be measured but which affect the primary process variable, a memory circuit for storing detected outputs supplied from the process variable detector units, a circuit for reading the detected outputs out of the memory circuit and then correcting the detected output indicative of the primary process variable based on the detected outputs indicative of the secondary process variables, and a power supply control for intermittently supplying electric power to the process variable detector units and the correcting circuit. The process variable transmitter corrects the primary process variable to precision and consumes a reduced amount of electric power.

Computer process control system

Abstract: A computer process control system includes at least one control section which is housed in a case and connected to a detection terminal and which automatically produces an operation signal for compensating for a difference between a process variable and a preset target value. At least one man-machine interface unit is included separate from the control section to display the process variable and the target value and to allow the operator to manually produce an operation signal. An output section is detachably connected to the control section and the man-machine interface unit and supplies one of the operation signals, in accordance with one of the corresponding operation modes, to a process actuator terminal. The man-machine interface unit is coupled to a selected loop to be supervised by the operator.

Measuring arrangement for determining a process variable of a winding arrangement

Abstract: A measuring arrangement for a machine winding arrangement can determine a process variable related to the length of a wound-up or let-off material. A rotational angle signal is extracted from a rotatable winding carrier. In addition this angle signal can also contain information concerning the direction of rotation of the winding arrangement. The process variable is then calculated from this turning angle signal and calculation data, by means of a computer. The calculation data, transmitted from an input device, include at least values which are concerned with the diameter of the winding and thickness of the winding layer. The computer can contemporaneously be utilized to calculate the desired amount of rotation of a beam motor from: the process variable, a setting amount from the input device and a main shaft signal indicating rotation of the main shaft of the winding arrangement. The arrangement is particularly suited for the winding up or letting off of thread of a textile machine.

Choice of Wear-Criteria in Fully Automated Turning

Abstract: In automated metal-cutting a high degree of machining-reliability is required. The performance of the cutting tool is of essential importance. The traditional wear-criteria, flank wear and crater wear, is not well correlated to the frequency of process interruptions due to tool performance. A system for machining-monitoring should therefore be based on other process parameters. In the paper cutting force is discussed as controlling process parameter in fully automated turning.

Process control device

Abstract: PURPOSE:To correct the measure value of a process variable rapidly, by providing a feed forward control device and a feedback control device in one control object to correct the measure value of the process variable on a basis of the deviation from a target value by the feedback control device. CONSTITUTION:A target value from a target value input terminal 17 for a combustion furnace 11 as a control object is given to a feed forward control device 16 and is subjected to a predetermined operation, and the operation result is given as a control output to a control valve 15 as a detecting terminal. The control valve 15 is controlled by the control output from the control device 16 to make a process variable of the combustion furnace 11 coincident with the target value. A feedback control device 13 is provided for the combustion furnace 11, and the process variable measured by a temperature detector 12 for measuring the process variable is inputted to the control device 13, and a deviation between the measure value and the target value is operated, and a correction value is calculated on a basis of this deviation. The correction value having positive and negative polarities from the control device 13 is given to the control valve 15 to correct the process variable rapidly.

Response time measuring system for process detection terminal converter

Abstract: PURPOSE:To realize the detection of the response time of a process detection terminal converter even under the operation of a plant where said converter is installed, by measuring the response time from the power spectrum of the output of the converter CONSTITUTION:The process variable delivered from a process detection terminal converter (a) installed at a plant is amplified by a DC amplifier (d) via a filter (c), and the output of amplification is supplied to a Fourier analyzer (e) to calculate and deliver the power spectrum of the process variable The power spectrum delivered from the analyzer (e) is supplied to a microcomputer (f) to calculate the broken point frequency f1 where the power spectrum density becomes 1/2 density of the power spectrum corresponding to frequency 0 Then the response time of the process variable (g) is calculated from the frequency f1

Controller for process having dead time

Abstract: PURPOSE:To achieve stable control even for a process where dead time is in variance, by applying the length of dead time in variance calculated with operation from the operation state date of the process to a controller with operator as a parameter. CONSTITUTION:A dead time compensator 11 inputs a process variable from a measurement value input section 18 for dead time compensation, and a control output as the result is transmitted to a process 16. A function operator 12 inputs a data signal obtained through an operation state signal input section 14, makes operation according to a specified function at a function set section 13, and the result is given to the dead time compensator 11 as a parameter Lc15. A controller 10 consists of them. Thus, even if the operating state of the process changes, the parameter Lc15 keeps a value near the true process dead time at all times, allowing control with safety.

Hierarchical Control of an Ammonia Reactor

Abstract: An approach is presented for hierarchical control of an ammonia reactor, which is a key unit process in a nitrogen fertilizer complex. The aim of the control system is to ensure safe operation of the reactor around the optimal operating point in the face of process variable disturbances and parameter variations. The four different layers perform the functions of regulation, optimization, adaptation, and self-organization. The simulation for this proposed application is conducted on an AD511 hybrid computer in which the AD5 analog processor is used to represent the process and the PDP-11/ 35 digital computer is used for the implementation of control laws. Simulation results relating to the different layers have been presented.