Reliability and risk analysis of process models

The IDEF methodology has been extensively used for modeling processes. Qualitative and quantitative reliability analysis and risk assessment of IDEF models is of interest to industry for several reasons. It identifies critical activities in a process, improves the process performance, and decreases downtime and operating cost of the process. To evaluate the reliability and risk associated with an IDEF3 model formal tools and techniques are required. This paper extends the system reliability evaluation techniques, i.e., the system reduction approach and minimum path and cut sets method for reliability evaluation of IDEF3 models. Representation of IDEF3 models as reliability graphs, generation of minimal path and cut sets of IDEF3 models with a path tree algorithm, and reliability analysis of IDEF3 models are the issues discussed in this paper. An algorithm for computing reliability of an IDEF3 model from a path set - activity incidence matrix is also presented. In addition, the fault tree analysis technique and minimum cut and path sets generation algorithms are applied for reliability evaluation and risk assessment of the parent activities in an IDEF3 model. A structural and reliability importance measure for parent activities in an IDEF3 model as well as for the elementary activities in a decomposed model are presented.