Dependability modeling and evaluation of multiple phased systems using DEEM

Bondavalli A., Chiaradonna S., Di Giandomenico F., Mura I.

Reliability  Modeling techniques 

Multiple-Phased Systems, whose operational life can be partitioned in a set of disjoint periods, called "phases", include several classes of systems such as Phased Mission Systems and Scheduled Maintenance Systems. Because of their deployment in critical applications, the dependability modeling and analysis of Multiple-Phased Systems is a task of primary relevance. However, the phased behavior makes the analysis of Multiple-Phased Systems extremely complex. This paper describes DEEM, a dependability modeling and evaluation tool specifically tailored for Multiple Phased Systems, and its use for the solution of representative MPS problems. DEEM supports the methodology proposed in [28, 29] although not yet completely. When compared to general purpose DSPN tools [17], DEEM offers advantages on the modeling side (PhN and SN sub-models neatly model the phase-dependent behaviors of MPS), and on the evaluation side (a specialized algorithm allows a relevant reduction of the solution cost and time). Thus, DEEM is able to deal with all the scenarios of MPS that have been analytically treated in the literature, at a cost which is comparable with that of the cheapest ones [7, 26, 27, 34], completely solving the issues posed by the phased-behavior of MPS. DEEM is freely available to the academic world, for information see http://bonda.cnuce.cnr.it/DEEM.

Source: ISTI Technical reports, 2002