Petri net and Markov chain models are developed for manufacturing systems with blocking and deadlock. The authors compute the probability that the system in an absorbing (deadlocked) state, the mean time to deadlock, ...
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Petri net and Markov chain models are developed for manufacturing systems with blocking and deadlock. The authors compute the probability that the system in an absorbing (deadlocked) state, the mean time to deadlock, and the throughput before deadlock, etc., which can be used to compare the performance of various prevention and avoidance strategies. A systematic method for designing locks and interlocks for deadlock avoidance using the reachability graph of the Petri net model is presented.< >
A likelihood ratio test is used to detect the portion of the prediction error variance caused by changes in parameters. It results in a simple rule for adjusting the dispersion factor in the parameter covariance matri...
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A likelihood ratio test is used to detect the portion of the prediction error variance caused by changes in parameters. It results in a simple rule for adjusting the dispersion factor in the parameter covariance matrix. The adaptation rule given by Jazwinski (1970) is shown to be a special case of one derived
作者：
L. RozsaDepartment of Process Control
Computer and Automation Institute of the Hungarian Academy of Sciences Kende u. 13-17 H 1111 Budapest Hungary
Literature on process control is awash with contributions made in the field of digital controller design. On the one hand there are great efforts to devise new control algorithms and controller design methods based on...
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Literature on process control is awash with contributions made in the field of digital controller design. On the one hand there are great efforts to devise new control algorithms and controller design methods based on elegant mathemtics and state variables concealing even the most rudiræntary inner workings of a real process. Results are mostly documented by simulations. On the other hand there are contributions directed towards improving the digital equivalent of the traditional PID controller. The debate over the virtues of different versions of the PID algorithm gave way lately to the adaptive tuning of these controllers. This way a definite shift of emphasis can be noticed, but - at least in the author’s opinion - a general view, encompassing all of the basic features of a practical digital PID controller is still lacking. This paper is an attempt to meet this need.
In this paper we present the semilattice-theoretical approach to the investigation of the relational datamodels. It is known that the poset of closures is a model of changing databases. We show that it is in fact a la...
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In a hard real-time distributed computing system (HRTDCS), all the tasks are required to meet their associated deadlines; a task not meeting its deadline leads to a catastrophic failure of the system. The authors cons...
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In a hard real-time distributed computing system (HRTDCS), all the tasks are required to meet their associated deadlines; a task not meeting its deadline leads to a catastrophic failure of the system. The authors consider an HRTDCS that executes both periodic and aperiodic tasks associated with timing, precedence, and resource constraints. The fault-tolerance capability in such a system is achieved through the use of time redundancy. The problem of workload redistribution for fault tolerance in an HRTDCS is studied. A graph model to represent the system workload is developed. Three performance measures for the analysis of an HRTDCS are defined. A nonpreemptive scheduling algorithm is proposed to distribute the workload of the operational nodes of the HRTDCS in the presence of both hardware and task failures. This task allocation strategy is applied to a practical system, namely, the HRTDCS onboard a spacecraft. The performance measures obtained for a typical system workload indicate that the algorithm is quite suitable for an HRTDCS with regard to uniform workload distribution.< >
In this paper, we propose and develop a two level scheme for monitoring and diagnosis in automated manufacturing systems. At the first level, there are dedicated diagnostic systems for each of the subsystems such as m...
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In this paper, we propose and develop a two level scheme for monitoring and diagnosis in automated manufacturing systems. At the first level, there are dedicated diagnostic systems for each of the subsystems such as machine centres, robots, conveyors, etc. At the second level we have an intelligent controller monitoring the part flow and coordinating the local diagnostic systems and controllers. We assume that local controller and diagnostic systems exist for subsystem level fault detection and diagnosis, and present a Petri net based intelligent controller for system level fault detection and diagnosis.
A new scheme for robust estimation of the partial state of linear time-invariant multivariable systems is presented, and it is shown how this may be used for the detection of sensor faults in such systems. We consider...
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A new scheme for robust estimation of the partial state of linear time-invariant multivariable systems is presented, and it is shown how this may be used for the detection of sensor faults in such systems. We consider an observer to be robust if it generates a faithful estimate of the plant state in the face of modelling uncertainty or plant perturbations. Using the Stable Factorization approach we formulate the problem of optimal robust observer design by minimizing an appropriate norm on the estimation error. A logical candidate is the 2-norm, corresponding to an H ∞ optimization problem, for which solutions are readily available. In the special case of a stable plant, the optimal fault diagnosis scheme reduces to an internal model control architecture.
The authors develop a controller methodology for fault detection and diagnosis using Petri nets and fault trees in automated manufacturing systems. The controller has two levels. At the first level there are dedicated...
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The authors develop a controller methodology for fault detection and diagnosis using Petri nets and fault trees in automated manufacturing systems. The controller has two levels. At the first level there are dedicated diagnostic systems for each of the subsystems, such as machine centers, robots, conveyers, etc. At the second level there is an intelligent controller monitoring the part flow and coordinating the local diagnostic systems and controllers. The authors assume that local controller and diagnostic systems exist for subsystem-level fault detection and diagnosis, and they present a Petri-net-based intelligent controller for system-level fault detection and diagnosis. The authors also describe fault-free-based diagnostics.< >
This paper is aimed at reviewing the notion of Byzantine-resilient distributed computing systems, the relevant protocols and their possible applications as reported in the literature. The three agreement problems, nam...
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This paper is aimed at reviewing the notion of Byzantine-resilient distributed computing systems, the relevant protocols and their possible applications as reported in the literature. The three agreement problems, namely, the consensus problem, the interactive consistency problem, and the generals problem have been discussed. Various agreement protocols for the Byzantine generals problem have been summarized in terms of their performance and level of fault-tolerance. The three classes of Byzantine agreement protocols discussed are the deterministic, randomized, and approximate agreement protocols. Finally, application of the Byzantine agreement protocols to clock synchronization is highlighted.
The authors present a program packaqe prepared for a personal computer of 64 kbytes. The program package is suitable for processing of measurement data, identification of control systems, design of controllers and sim...
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The authors present a program packaqe prepared for a personal computer of 64 kbytes. The program package is suitable for processing of measurement data, identification of control systems, design of controllers and simulation. The console communication is interactive and plotting is graphic on both the screen and the printer. Time series data are stored in files and the appropriate programs write in and read from the files. The operation of the programs is illustrated by examples.
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