Formal Semantics and Verification of Dynamic Reliability Block Diagrams for System Reliability Modeling

With the rapid advances in computer science and technology, critical computer-based systems, such as those in aerospace, military, and power industries exhibit more complex dependent and dynamic behaviors, which cannot be fully captured by existing reliability modeling tools. In this paper, we introduce a new reliability modeling tool, called dynamic reliability block diagrams (DRBD), for modeling dynamic relationships between components, such as state dependency and redundancy. We give formal semantics for some key DRBD constructs using Object-Z formalism. In order to verify and validate the correctness of a DRBD model, we propose to convert a DRBD model into a colored Petri net (CPN), and use an existing Petri net tool, called CPN Tools, to analyze and verify dynamic system behavioral properties. Our case study and experimental results show that DRBD provides a powerful tool for system reliability modeling, and our proposed verification approach can effectively ensure the correct design of DRBD reliability models for complex and large-scale computer-based systems.