Optimized Bdd-based Dynamic Fault Tree Analysis

Nowadays, Fault Tree Analysis (FTA) has been widely used in the assessing of reliability and safety of systems. An active FTA constructing method, qualitative and quantitative as well as module analysis of FTA based on Binary Decision Diagram (BDD) was researched in this thesis. Including the following areas of contents:First, based on Windows interface, a design and implementation method of computer aided active FTA constructing method was presented. According to this method, the visualized active fault tree construction software was developed. And the worse versatility and huge working load problems of FTA construction were solved.Then, the optimal ordering permutation for the basic events of fault tree was produced by structural importance and neural network methods respectively, and the resulting size problem of BDD affected by the basic events' order was solved. According to the relationship of Shannon's formula of Boolean functions and BDD, the fault tree structure to BDD conversion was accomplished by recursive method.After then, a new method of solving the minimal cuts of s-coherent tree based on BDD and prime number was given in the qualitative analysis of FTA based on BDD, the prime implicant sets of non s-coherent tree was calculated by an iterative method. The probability and unconditional failure intensity of top event was computed in the quantitative analysis of FTA based on BDD. A Fault Tree Module Analysis (FTMA) based on. depth-first left-most traversals and BDD was presented to solve large complicated FTA problems. And the automatic computer analysis was implemented. The long exist NP (Non-deterministic Polynomial) problems of FTA based on Boolean algebra was solved by these methods.Finally, the relationship of FTA and Reliability Block Diagram Analysis (RBDA) was studied, and the complementation relation of their results was first verified.