HIERARCHICAL, COMBINATORIAL-MARKOV METHOD OF SOLVING COMPLEX RELIABILITY MODELS.
Combinatorial models such as fault-trees and reliability block diagrams are efficient in both specification and evaluation of system models, but it is difficult if not impossible to allow for various types of dependency, transient and intermittent faults, standby systems with warm spares, etc. , Markov models can capture such interesting system behavior, however, the size of a Markov model for the evaluation of such a system may grow exponentially with the number of components in the system. A modeling tool is presented which is called SHARPE (symbolic hierarchical automated reliability and performance evaluator). It is a general hierarchical modeling tool for analyzing complex reliability models. SHARPE allows its user complete freedom to choose the number of levels of models and the type of model (combinatorial or Markov) at each level. Thus it allows the flexibility of Markov models where necessary and retains the efficiency of combinatorial solution where possible. The analysis of each model produces a probability function that is symbolic in the time variable t.
