Entrapped caustic liquor in the red mud residue, a by-product of the Bayer process used to produce alumina from bauxite ores, is recovered in a series of counter-current, multi-stage washer trains using the process di...
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Entrapped caustic liquor in the red mud residue, a by-product of the Bayer process used to produce alumina from bauxite ores, is recovered in a series of counter-current, multi-stage washer trains using the process diluting water. Co-ordinated control of the operation of the washer trains is difficult owing to both the long-time constants of elements of the plant, which cause delays between corrective actions and observable effects, and the imprecisely-known interaction of disturbances in composition and rate of the counter-current flows. A dynamic simulation model has been developed for a multi-stage washer train using SLAM II in order to gain understanding of the dynamic behaviour of the system, to identify significant control variables and objectives and to derive a set, or sets, of operating variables that would maximize the caustic soda gain from the washing operation. A feed-forward, feed-back control strategy has been developed and implemented to control liquor and mud levels in a washer tank, and thereby maintaining the mud-liquor interface close to a 'desired' level.
This paper addresses closed-loop computer control with noisy models and a noisy environment. control system engineers are always looking for ways to decrease the sensitivity of a process to external distrubances. Good...
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This paper addresses closed-loop computer control with noisy models and a noisy environment. control system engineers are always looking for ways to decrease the sensitivity of a process to external distrubances. Good control requires vigilance, rapid responses, and accurate reproducible responses. Recognizing that humans are not good at these characteristics, we have had various degrees of success in automating processes using computers. The implementation of advancedcontrol, let alone optimal dynamic control, in the petroleum and chemical industries is only just now being successful. The approach taken in the petroleum and chemical industry is to design the plants for human operation. The human operator is expected to provide process feed-back and guidance. This requires, whenever possible, slowing plant dynamics and reducing interactions. Thus storage and surge capacities are designed into a process. Economic considerations are forcing the elimination of these expensive practices and thus automation becomes urgent.
A procedure for compensating for the effects of distributed network-induced delays in integrated communication and control systems (ICCS) is proposed. The problem of analyzing systems with time-varying and possibly st...
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A procedure for compensating for the effects of distributed network-induced delays in integrated communication and control systems (ICCS) is proposed. The problem of analyzing systems with time-varying and possibly stochastic delays could be circumvented by use of a deterministic observer which is designed to perform under certain restrictive but realistic assumptions. The proposed delay-compensation algorithm is based on a deterministic state estimator and a linear state-variable-feedback control law. The deterministic observer can be replaced by a stochastic observer without any structural modifications of the delay compensation algorithm. However, if a feedforward-feedback control law is chosen instead of the state-variable-feedback control law, then the observer needs to be modified in the same way a conventional nondelayed control system should be. Under these circumstances, the delay compensation algorithm would be accordingly changed. The separation principle of the classical Luenberger observer holds true for the proposed delay compensator. The algorithm is suitable for integrated communication and control systems (ICCS) in advanced aircraft, spacecraft, manufacturing automation, and chemical process applications.
High reliability and a quick and appropriate response to abnormal conditions are required for operation of city gas production plants. To respond to these needs, the real-time expert system GAPOS (gas advanced plant o...
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ISBN:
(纸本)0879426004
High reliability and a quick and appropriate response to abnormal conditions are required for operation of city gas production plants. To respond to these needs, the real-time expert system GAPOS (gas advanced plant operation support system) has been developed by the Tokyo Gas Company on the basis of minicomputers and an inference engine with numeric analysis, man-machine functions, etc. This system links the analysis functions of process time series data and a rule-type knowledge base and not only investigates the causes of abnormalities but also makes predictions about the potential for abnormalities. Basic performance has been proven with a prototype of approximately 2000 rules for a calorie control plant, and development has begun on the practical application of such a system.< >
The process supervision in offshore platforms was performed in the past through the use of local pneumatic instrumentation, based on relays, semi-graphic panels and button operated control panels. Considering the adva...
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The process supervision in offshore platforms was performed in the past through the use of local pneumatic instrumentation, based on relays, semi-graphic panels and button operated control panels. Considering the advanced technology used in the new floating production projects for deep water, it became mandatory to develop supervision systems capable of integrating different control panels, increasing the level of monitorization and reducing the number of operators and control rooms. From the point of view of field integration, a standardized architecture makes the communication between different production platforms and the regional headquarters, where all the equipment and support infrastructure for the computerized network is installed, possible.
Very-large-scale integration (VLSI) manufacturing techniques in Japan are compared with those in the United States. Factory design, employment practices, random vs. causal yield fluctuations, processcontrol and produ...
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Very-large-scale integration (VLSI) manufacturing techniques in Japan are compared with those in the United States. Factory design, employment practices, random vs. causal yield fluctuations, processcontrol and productivity, and computer integrated manufacturing (CIM) systems are discussed.< >
Summary form only given. There has been continued progress in the area of software measurement. The main inroads have been made in the scope of measurement, a deeper understanding of the perspectives from which measur...
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Summary form only given. There has been continued progress in the area of software measurement. The main inroads have been made in the scope of measurement, a deeper understanding of the perspectives from which measurement can be applied, the development of frameworks for the definition and interpretation of measurement, the refinement of the measures and the models on which the metrics are based, the automation of the models and measures, and the increased application of measurement in many organizations.< >
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