中文摘要：

故障树分析（Fault Tree Analysis，FTA）是对系统进行可靠性分析的一种有效方法。而在现在所有的故障树分析中，二元决策图（Binary Decision Diagram，BDD）又是其中最有效的方法之一。由于BDD的节点数在很大程度上依赖于输入的底事件的排列次序，所以从故障树到BDD的转换过程中，需要先对底事件进行排序。而如何对底事件进行有效的排序则成为一个重要且未完全解决的课题。本文提出了一种新的底事件排序法——相邻底事件优先法。其基本思想是利用故障树的相邻关系来给其赋予不同的排序优先级。该排序方法所具备的特点包括：其底事件排序过程是静态的，但在BDD的构造过程中，能动态地对已经排序的底事件进行筛选，同时它还支持在BDD的不同分支采用不同的底事件排序方法。实验证明，与现有的最优方法相比，相邻底事件优先法可有效提高75％的故障树的BDD转化效率。

英文摘要：

Fault tree analysis（FTA） has been widely used for quantitative and qualitative analysis on the reliability of a system. An efficient way to analyze a fault tree is binary decision diagram （BDD） method, which can take advantage of computer technology to automatically deal with a large scale fault tree. However, in order to use this method, the fault tree has to be converted into a BDD format first. During the conversion process, the event-ordering problem is a key issue for a good BDD＇s generation. In this paper, a novel ordering method, named as neighbor-event-first method, is proposed. In the new method, the order of the basic event variables is determined based on their relevant position to each other. The major characteristic of the neighbor-event - first method is that the ordering process follows a pre-defined way while it can also allow different ordering strategy in BDD branches. Compared with the existing best BDD ordering heuristics, the proposed scheme can achieve performance improvement on 75% of test cases.