证据理论在泵站老化评价中的应用

为了提高泵站老化等级确定的可信度,建立基于证据理论的泵站老化评价模型.以2座典型泵站为例,提取各项老化指标信息,请3位专家按照老化评价标准,对指标体系中的最底层指标,在每个老化等级上进行单独评分,并且经可信度归一化处理,每个评分作为一条证据,按照Dempster合成法则计算,得到每个最底层指标在识别框架上的可信度分配;然后,每个最底层指标在识别框架上的可信度分配作为一条证据,按照Dempster合成法则及带权重的证据理论合成公式层层计算,得到泵站的综合管理、机电设备、建筑物、金属结构以及泵站整体在识别框架上的可信度分配;最后按照给定公式,计算评分并确定老化等级.与应用模糊层次综合评价模型计算的结果比较,在识别框架上,除了出现难以解决的证据冲突的情况外,同一指标的最大可信度平均是最大模糊隶属度的2.4倍,且两者对应的老化等级相同,应用证据理论可以提高泵站老化等级确定的可信度;合成证据前,对每条证据进行归一化处理,可以较好地解决合成过程中出现合成信度大于1的异常情况 .

Application of evidence theory for aging degree evaluation in pumping station

To increase the credibility of determining the aging degree grade of pumping station,a new pumping station aging degree evaluation model based on evidence theory was built.Taking two typical pumping stations as examples,from which aging information was extracted for each index.According to pumping station aging evaluation standard,three experts were asked to give score separately on each aging degree grade for basic indices of the index system and each score as one piece of evidence after being normalized.According to the Dempster combination rule,pieces of evidence were composited to get credibility allocation of each basic index on framework of recognition as one piece of evidence.Pieces of evidence were composited in accordance with this rule and evidence synthesis formula with weighting factor,credibility allocation on framework of recognition of integrated management,electrical and mechanical equipment,buildings,metal structures and the whole pumping station figured out.Then ultimate score of pumping station aging degree was calculated according to a given formula,and aging degree grade of pumping station was found out in contrast with a given table.Compared with results from model of fuzzy-AHP comprehensive evaluation model,to some index on frame of discernment,the maximum credibility is 2.4 times as much as the maximum fuzzy membership,and both of them correspond to the same aging degree grade,except evidence conflict situation which is difficult to resolve.It showed that application of evidence theory can increase determination of pumping station aging degree grade.Each piece of evidence is necessary to be normalized before evidence combination,which can well solve situation in which the composited credibility is likely to be greater than 1.