Formalization and Petri net-Based Extension to Model Factors of State-Varying Failures for Reliability Modeling

Failures are very often affected by many other factors besides the time. In reality, very often, these factors are neglected, leading to misleading conclusions about reliability of stochastic systems. In this paper we identify the key factors that contribute to failure rates of various stochastic systems. We further formalize them and provide solutions for their modeling using stochastic Petri nets. The latter one is a challenging task for certain classes of factors, thus we have extended the classic Petri net formalism by new elements to facilitate the accurate modeling of these types of failures, which we term as state-varying failures. We illustrate how each of the factors is modeled by Petri nets.