安全关键系统的软件可靠性评估方法

基于统计测试的Markov使用链模型对安全关键系统的可靠性估计提出了一种有效的方法。该方法利用重要抽样技术在保证佑计的无偏性条件下，以可靠性估计的方差最小为目的，通过Ali-Silvey距离度量两个分布之间的差异，调整各个状态之间的转移概率分布，修正测试剖面，增加关键操作的遍历概率。最后给出了软件可靠性估计的最优测试剖面生成迭代算法。仿真结果表明，该方法能明显降低估计方差，在提高估计精度的同时能有效地加速统计测试。

Estimation Method of Software Reliability for Safety-critical System

Importance sampling is a changcof-measure technique for speeding up the simulation of rare events in stodrastic systems. In this paper we established a technictue for computing optimal state transition probabilities for software reliability estimation based on a Markov usage model. I3y suitable changes of the probabilities of state transitions during test, an iterative method based on the Ali Silvey distance was proposed for this choice. A learning algorithm for the computation of optimal transition probabilities of the Markov chain usage model was also presented and experimental results of this algorithm were reported.