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Non-coherent modelling in compositional fault tree analysis

Sharvia, Septavera; Papadopoulos, Yiannis Ioannis



The inclusion of NOT gates in a fault tree creates a 'non-coherent' structure in which not only the failure of a component but also the negation of failure, i.e. the working state of the component, can contribute to the undesirable effects on a system. This type of non-coherent modelling remains controversial; its usefulness is still debated among academics, which explains why NOT gates have not been included in the Fault Tree Handbook. In this paper, we review work on non-coherent fault trees and highlight circumstances where non-coherent modelling is appropriate and useful. We then describe an extension to HiP-HOPS (Hierarchically Performed Hazard Origin and Propagation Studies), a recently proposed compositional safety analysis method, that enables model-based synthesis and analysis of non-coherent fault trees. A small example is given to illustrate application of the extended method and demonstrate how this type of non-coherent modelling can give a more precise and ultimately more correct insight into failure behaviour. Copyright © 2007 International Federation of Automatic Control All Rights Reserved.


Sharvia, S., & Papadopoulos, Y. I. (2008). Non-coherent modelling in compositional fault tree analysis. IFAC Proceedings Volumes/ International Federation of Automatic Control, 41(2), 4138-4143.

Journal Article Type Conference Paper
Online Publication Date Apr 25, 2016
Publication Date Dec 1, 2008
Deposit Date Jul 13, 2021
Journal IFAC Proceedings Volumes (IFAC-PapersOnline)
Print ISSN 1474-6670
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 41
Issue 2
Pages 4138-4143
ISBN 9783902661005
Public URL