Research On Computer-Aided Software Fault Trees Modeling And Analysis

Software Fault Trees Analysis (SFTA) is an important software hazard analysis while Software Fault Trees (SFT) modeling and analysis are time-consuming. This thesis introduces computer-aided technology in the modeling and analysis of SFT, and an automatic modeling algorithm and a quick analysis algorithm are presented. The main contents are listed as following:1) SFT modeling and analysis are introduced detailedly: in the introduction of SFT modeling, a set of failure mode templates of C/C++ language is presented, and the backward method of modeling is also discussed; in the introduction of SFT analysis, the purport of qualitative analysis and quantitative analysis is given, the dispute about quantitative analysis is pointed out, two classical anlysis methods are introduced, and an example of modeling and analysis is also given.2) Through introducing the weakest predication, the fundamental and essence of SFTA are discussed. Based on comparison with software testing, proof of program correctness and other analysis methods, advantages and disadvantages of SFTA are summarized.3) An automatic SFT modeling algorithm is presented. The first half part of the algorithm, which uses compilers front end techniques, includes lexical anslysis based on states transition diagrams, construction of suitable grammars for top-down parsing, recursive-descent parsing, and syntax-directed construction of syntax trees. The second half part of the algorithm includes extension of syntax trees based on breadth first traverse and construction of SFT based on depth first traverse.4) A quick SFT analysis algorithm is presented. The algorithm includes a fault trees logical reduction strategy based on greedy algorithm, a fault trees modularizing strategy based on depth first traverse, analysis of modules and synthesis of modules results based on extended cut set matrix. The data structure of cut set matrix is presented, and primary testing results are also given.