Showing papers on "Process variable published in 1989"

Morphological studies of blends containing liquid crystalline polymers with poly(ethylene terephthalate)

Abstract: The investigation involved the structure–property behavior of extruded cast films prepared from blends of thermotropic liquid crystalline copolyesters with poly(ethylene terephthalate) (PET). Data were obtained which showed not only the temperature dependence of the moduli and stress–strain behavior but also the orientation effects that must be prevalent in order to explain the differences between the moduli measured parallel and perpendicular to the extrusion direction. Only at high liquid crystal polymer (LCP) composition is the modulus particularly increased. The modulus enhancement with lower LCP content and utilization of process variables are discussed with respect to the induced morphological textures and nature of the process equipment. Specifically, the process variable extruder gear pump speed did not enhance Young's modulus at the same LCP content as extensively as did the process variable of extruder screw speed.

Continuous viscosity monitoring of glass

Abstract: A method for manufacturing glass comprises forming glass from molten mineral material, continuously discharging an auxiliary stream of molten mineral material, continuously measuring the temperature and the mass flow rate by laser means of the auxiliary stream, calculating the viscosity of the material using the measured mass flow rate and modifying a process parameter in response to the measured temperature and calculated viscosity of the auxiliary stream. The laser means is also disclosed.

Charge Controlled Reproducible Ion Exchange For Buried Strip Waveguides In Glass

Abstract: Integrated optical components in glass are commonly fabricated by thermal or field assisted ion exchange. We introduce the charge controlled field assisted ion exchange. A reproducible fabrication of optical wave-guides is achieved by using the exchanged charge as the controlling process parameter. The ion current is integrated by a computer controlled unit which stops the process at a preset charge. The charge corresponds to the amount of exchanged ions and a reproducible process is available. Introducing the exchanged charge as the process determining parameter requires a resistant mask material and a special vacuumchuck containing the anode melt and holding the wafer. This is necessary to exclude any leak current during the exchange process. We get resistant masks only when using oxide coatings, which are formed by an anodic oxidation of evaporated aluminium films in a dilute ammonium-tartrat solution [(NH4)2C2H4O6]. It takes only several seconds to fabricate single mode waveguides in glasses such as B-270 (Desag) and BK-7 (Schott) at a temperature of 693 K and an applied electrical field of SO V/mm. Directional couplers are extremely sensitive to parameter deviations . They were used to control the reproducibility of the process. Buried multimode waveguides with a circular cross section have been fabricated by a two step ion exchange in B-270 glass.© (1989) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Modular Multivariable Control Applied to the Shell Heavy Oil Fractionator

Abstract: Modular multivariable controllers use interconnections of single process variable-multiple control effort controllers (i.e. Coordinated Controllers) plus logic to control multiple, possibly constrained, process variables with multiple, constrained, control efforts. The number of controls may be greater or fewer than the number of process variables. In the event that not all control objectives can be met, then process variables with higher user assigned priorities are kept at their targets in preference to process variables with lower priorities. When there are more controls than process variables which are to be maintained at set points, then the excess controls can be assigned nominal values and priorities. After all process variable objectives are met, the excess controls will achieve their nominal values, again in order of user assigned priority. We propose a modular multivariable control structure (i.e. process variable and control effort priorities) which should lead to a complete solution to the Shell Heavy Oil Fractionator Problem. The structure is justified based on performance objectives and robustness considerations. In addition, we compare the control achieved by a simple MMC (modular multivariable control) implementation to those achieved by Shell's QDMC approach for setpoint changes for a two control effort, two process variable subset of the complete problem.

Device for detecting and evaluating process parameters which arise during the remelting of an electrode to give a metal block in a vacuum arc furnace

Abstract: The invention relates to a device for detecting and evaluating process parameters which arise during the remelting of an electrode (31) to give a metal block (32) in a vacuum arc furnace. In this case, deviations of at least one process parameter from a predetermined course are detected and assigned to faults in the electrode and/or in the metal block (32) (Fig. 5).

Automatic control process and device, in particular lambda control

Abstract: A process for adapting the pilot control value of a control system is based on the fact that when the service conditions match the calibration conditions for the initial determination of pilot control values, no deviation of the correcting variable may occur in any operating area and on the fact that, accordingly, the deviations that nevertheless occur indicate that the calibration conditions no longer exist. This can be caused by the effects of aging or by uncompensated disturbances. Said process consists in determining the differences in the deviations of the correcting variable according to the different classes of an actuating variable. For each class of the actuating variable, a correcting value is then determined in such a way that said correcting value should compensate the previously observed error for the corresponding area during operation of the control member. Said process provides precise sectorial adaptation in an off-line process and is thus particularly suited for the pilot control of the lambda-value of an internal-combustion engine. Devices required for implementing said process are low-cost microcomputers which are too limited in their operating speed to perform complicated adaptation procedures on line; but if said devices are provided with a counter panel which can be interpreted off line, they are perfectly suitable for precise, i.e. sectional adaptation.

Method for evaluating operating state of plant

Abstract: PURPOSE:To make the title method economical and to always correctly evaluate the operating state of a plant deciding the existence of abnormality in a process variable detected by collective decision based on mutual cause and effect relation between respective process variable featured by the constitution of the plant CONSTITUTION:At the time of inputting abnormal signals from respective diagnosis parts 101-104, a process state integrated diagnosis part 106 decides the existence of abnormality in a process variable P2 eg by decision logic based on the mutual relation between respective signals, and when a detector is abnormal, outputs a signal 201 Simultaneously, the integrated diagnosis part 106 outputs a normal forecasting value request signal 202, finds out a normal forecasting value from its relational formula, inputs the obtained value to a process signal processing part as a forecasting value P2' 203, and substitutes the P2' for P2 to evaluate the process variable of the plant Consequently, the operating state of the plant can be always correctly evaluated for all plant operation by said simple method without forming a complex plant simulation model

Charge controlled ion exchange--a way to reproducible fabrication of integrated optical components in glass

Abstract: Integrated optical components in glass are commonly fabricated by thermal or field assisted ion exchange. We introduce the charge controlled, field assisted ion exchange. This process provides some advantages compared to thermal exchange. Exchange time is reduced remarkably, the waveguides can be buried and the index profile can be formed to a nearly circular cross section. A reproducible fabrication of optical waveguides is achieved by using the exchanged charge as the controlling process parameter. The ion current is integrated by a computer controlled unit which stops the process at a preset charge. The charge corresponds to the amount of exchanged ions and a reproducible process is available. It takes only several seconds to fabricate single mode waveguides in glasses like B-270 (Desalt) and BK-7 (Schott) at a temperature of 693 K and an applied field of 50 V/mm. Directional couplers are extremely sensitive to parameter deviations. They are used to control the reproducibility of the process. The measured variations of the coupling ratio were below 10 percent.