一种不改变RBD拓扑结构的三态贝叶斯网络

A three-state Bayesian network without changing the topology of RBD

针对将可靠性框图(RBD)转化为等价三层贝叶斯网络(BN)时存在的与RBD结构差异大的缺陷及组合爆炸问题,提出了一种将RBD转化为同构三态BN网络的方法.通过将失效分为"物理故障"和"正常却不工作"两种模式,提出将网络节点转换为包含正常状态以及上述两种失效模式的三态节点,取代仅有正常和失效两种模式的传统模型节点.并在此基础上深入分析了三态BN模型节点的条件概率表(CPT)设置方法.最后建立了与某型飞机航行任务RBD等价的三层BN模型和同构三态BN模型,并对两种BN进行分析计算.理论和实例分析均表明,本文建立的三态BN不仅与原RBD拓扑结构相同,且能够有效解决三层BN存在的组合爆炸问题,可成为系统可靠性分析的有效手段.

An isomorphic three-mode Bayesian network （BN） method is proposed based on the topology of reliability block diagram （RBD）. It overcomes the disadvantages to transform a RBD to an equivalent three-layer BN in terms of large topology distinction and combinational explosion problems. There are two modes -- normal and failure in traditional RBD and three-layer models, in this paper the failure mode is further divided into two new modes： physical failure and normal but not work. Accordingly, a three-mode BN model with normal, physical failure and normal but not work is formulated to replace the original two-mode BN model. Then the conditional probability table （CPT） of each node in the three-mode BN is analyzed in further. Eventually, the equivalent three-layer BN and isomorphic three-mode BN are built for the RBD of the navigation mission of an aircraft, the two BNs are calculated and analyzed. The results demonstrate that the new three-mode BN model, which can overcome the combinational explosion problem, is an effective method for system reliability analysis.