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Title: Dependability analysis of systems with on-demand and active failure modes, using dynamic fault trees
Authors: Meshkat, Leila
Dugan, Joanne Bechta
Andrews, J.D.
Keywords: Dynamic fault-tree
Markov analysis
On-demand failure
Standby system
Issue Date: 2002
Publisher: © IEEE
Citation: MESHKAT, L., DUGAN, J.B. and ANDREWS, J.D., 2002. Dependability analysis of systems with on-demand and active failure modes, using dynamic fault trees. IEEE Transactions on Reliability, 51 (2), pp 240-251
Abstract: Safety systems and protection systems can experience two phases of operation (standby and active); an accurate dependability analysis must combine an analysis of both phases. The standby mode can last for a long time, during which the safety system is periodically tested and maintained. Once a demand occurs, the safety system must operate successfully for the length of demand. The failure characteristics of the system are different in the two phases, and the system can fail in two ways: 1) It can fail to start (fail on-demand), or 2) It can fail while in active mode. Failure on demand requires an availability analysis of components (typically electromechanical components) which are required to start or support the safety system. These support components are usually maintained periodically while not in active use. Active failure refers to the failure while running (once started) of the active components of the safety system. These active components can be fault tolerant and use spares or other forms of redundancy, but are not maintainable while in use. The approach, in this paper, automatically combines the “availability analysis of the system in standby mode” with the “reliability analysis of the system in its active mode.” The general approach uses an availability analysis of the standby phase to determine the initial state probabilities for a Markov model of the demand phase. A detailed method is presented in terms of a dynamic fault-tree model. A new “dynamic fault-tree construct” captures the dependency of the demand-components on the support systems, which are required to detect the demand or to start the demand system. The method is discussed using a single example sprinkler system and then applied to a more complete system taken from the offshore industry.
Description: This is a journal article. It was published in the journal IEEE Transactions on Evolutionary Computation [© IEEE) and is also available at: http://ieeexplore.ieee.org. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.
URI: https://dspace.lboro.ac.uk/2134/3745
ISSN: 0018-9529
Appears in Collections:Published Articles (Aeronautical and Automotive Engineering)

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