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Reliability modeling of fault tolerant control systems

100%

Li H. , Zhao Q. , Yang Z.

tom 17

nr 4

491-504

This paper proposes a novel approach to reliability evaluation for active Fault Tolerant Control Systems (FTCSs). By introducing a reliability index based on the control performance and hard deadline, a semi-Markov process model is proposed to describe system operation for reliability evaluation. The degraded performance of FTCSs in the presence of imperfect Fault Detection and Isolation (FDI) is reflected by semi-Markov states. The semi-Markov kernel, the key parameter of the process, is determined by four probabilistic parameters based on the Markovian model of FTCSs. Computed from the transition probabilities of the semi-Markov process, the reliability index incorporates control objectives, hard deadline, and the effects of imperfect FDI, a suitable quantitative measure of the overall performance.

Method of availability control of the transport means

100%

Woropay M. , Migawa K. , Neubauer A.

tom Vol. 20, No. 4

485--492

The problems presented in this article deal with operation and maintenance process control in complex systems of technical object operation and maintenance. The article presents the description of the method concerning the control availability for technical objects (means of transport) on the basis of the mathematical model of the operation and maintenance process with the implementation of the decisive processes by semi-Markov. The presented method means focused on the preparing the decisive for the operation and maintenance process for technical objects (semi-Markov model) and after that specifying the best control strategy (optimal strategy) from among possible decisive variants in accordance with the approved criterion (criteria) of the activity evaluation of the system of technical objects operation and maintenance. In the presented method specifying the optimal strategy for control availability in the technical objects means a choice of a sequence of control decisions made in individual states of modelled operation and maintenance process for which the function being a criterion of evaluation reaches the extreme value. In order to choose the optimal control strategy the implementation of the genetic algorithm was chosen. Depending on one’s needs, the genetic algorithm including the obtained model of operation and maintenance process may be implemented for mathematic formulation and solution of a wide array of problems connected with control of complex systems of technical object operation and maintenance. It pertains mostly to the economic analysis, safety management and controlling availability and reliability of complex systems. The opinions were presented on the example of the operation and maintenance process of the means of transport implemented in the real system of the bus municipal transport.

Statistical identification and prediction of the port oil pipeline system’s operation process and its reliability and risk evaluation

100%

Kołowrocki K. , Soszyńska J.

tom Vol. 2

241--250

In the paper a Semi-markov processes are used to construct a general model of complex industrial systems’ operation processes. Main characteristics of this model are determined as well. In particular case, for a port oil pipeline transportation system, its operation states are defined, the relationships between them are fixed and particular model of its operation process is constructed and its main characteristics are determined. Further, the joint model of the system operation process and the system reliability is defined and applied to the reliability and risk evaluation of the port oil pipeline transportation system.

Comparative analysis of results of application of markov and semi-Markov processes to reliability models of multi-state technical objects

75%

Rudnicki J.

tom Vol. 11, no 1

169--181

During rational operation of technical objects and systems various operational decisions are made and decision-making process itself should be consisted in selecting that considered most favourable out of all possible to be taken. Choice of such decision is possible after taking into account many different information items but it never be completely correct without accounting for data and indices dealing with reliability. In the case when probabilistic principle of failure occurrence is determined , values of reliability indices can be estimated by using reliability mathematical models. During operation of many technical devices and systems ( e.g. ship main propulsion systems ) was observed many times the fact that their correct operation time is not a unique measure of their wear. Therefore for description of their serviceability and reliability can be used models of change of their reliability states in the form of semi-Markov processes based on the assumption of multi-state character of technical objects. This paper presents a comparative analysis of results of simulation reliability tests of a hypothetical technical object , obtained with the use of reliability models in the form of Markov processes and semi-Markov ones, corresponding to them, called also “half-Markov” processes.