具有Fuzzy概率的Fuzzy可靠性问题的求解途径

本文提出了工程实践中常见的清晰事件－Ｆｕｚｚｙ概率的Ｆｕｚｚｙ可靠性分析问题的求解途径，首先讨论了Ｆｕｚｚｙ数的代数运算法则，然后在此基础上将Ｆｕｚｚｙ可靠性求解问题转换为Ｆｕｚｚｙ数的运算问题，从而使这类Ｆｕｚｚｙ可靠性分析问题在理论上得到解决，本文还给出了一个算例。     

模糊重要度分析方法的研究

阐述故障树分析中从精确到模糊的重要分析法,提出了模糊重要度分析的新方法－中值法,它是用模糊故障树分析技术对结构复杂的新型系统进行可靠性、贮存可靠性研究的重要组成部分。同时,本文用两种模糊重度分析方法对一故障树作了重要度分析。     

串联系统的模糊可靠性

这篇文章是“模糊可靠性”的续篇之一。文中作者建立了串联系統模糊可靠性的计算模型,并依据模糊可靠性的基本概念和原理推导出一套计算公式。     

利用等可能性计算概率

许多通常要用全概公式或逆概公式来求解的问题事实上可以不用全概公式或逆概公式而直接利用等可能性。例 1　装有 m( m≥ 3 )个白球和 n个黑球的罐子中失去一球 ,但不知是什么颜色。为了猜测它是什么颜色 ,随机地从罐中摸取两个球 ,结果都是白球 ,问失去的球是白球的概率是什么 ?解法一　本题一般是利用全概公式和逆概公式来求解的。设 A={失去一球是白球 } ,B={随机地从罐中摸取两个球 ,结果都是白球 } ,由已知条件 P( A)= mm+n,P( A) =nm+n,P( B|A) =C2m- 1C2m+n- 1,P( B|A) =C2m C2m+n- 1,本题求的是 P( A|B)。由全概公式P( …     

基于模糊故障树的高速列车电流互感器可靠性分析

针对目前高速列车差动保护系统所使用的直通式电流互感器的结构与运行方式,结合主要元件的故障模式和机理,构建故障树模型,采用下行法计算其最小割集为84个,利用专家评分法与梯度模糊数相结合的方法计算故障树各个底事件与中间事件的发生概率及其权重,进而计算出顶事件的失效概率,发现其可靠度较高,其中绕组故障对顶事件(电流互感器失效)的贡献度最高,通过与传统的模糊故障树分析法作比较,体现出了本文所提算法的优越性。可为高速列车电力牵引系统的可靠性量化分析与评估奠定基础,为动车组电流互感器的运营维护决策提供依据。     

基于FTA-FPN的动车组塞拉门系统可靠性分析

基于动车组塞拉门系统故障的多样性以及故障征兆的模糊性,本文提出故障树(FTA)定性分析和模糊Petri网(FPN)定量分析相结合的可靠性分析方法,将Petri网理论和模糊推理规则有效结合,具有快速准确的并行推理能力。结合兰新客专动车组实际的运维记录,首先建立基于FTA的塞拉门系统模型,再根据FTA-FPN的转换规则,得到基于FPN的可靠性分析模型。当系统正常工作时,利用历史故障数据和FPN的正向矩阵推理对塞拉门系统进行可靠性分析得到了塞拉门系统的薄弱环节,并对各底事件进行了排序,这不仅能够为动车组塞拉门系统的维护与预防工作提供理论依据,还能更好的保证动车组安全运营。     

以模糊数排序为基础的可能性线性规划分析——兼与文献[1]作者商榷

对文献 [1]提出的可能性线性规划的非模糊等价模型从模糊数排序分析的角度阐述并举证了该模型的非有效性。因而 ,以此为基础对原规划作出的变换被视为不良变换。为克服这一缺陷 ,提出相应的改正模型 ,并结合例题进行比较分析。     

模糊技术在可靠性工程中的应用

本文主要介绍模糊集合理论和技术在可靠性工程中的应用现状及其发展趋势，尤其是在系统故障诊断，故障树分析（ＦＴＡ）系统可靠性分配，人的可靠性，软件可靠性，结构可靠性以及系统安全性工程中的应用和技术关键，并从工程应用的需要出发针对存在问题预测和提出各种解决途径。     

产品无失效数据的可靠性分析

本对某型发动机的无失效数据,给出了失效概率的多层Bayes估计,从而可以得到该型发动机可靠度的估计,并结合该型发动机的实际问题进行了计算。     

基于模糊随机变量的结构可靠性分析

研究了广义应力和广义强度同时具有模糊性和随机性时的结构可靠度计算问题,基于模糊随机变量和模糊随机事件的理论,建立了结构模糊可靠度的计算模型.最后通过一算例,验证了该方法的有效性和合理性.     

Synthesis and analysis of temporal fault trees with PANDORA: The time of Priority AND gates

Classical Fault Tree Analysis (FTA) can determine the effects of combinations of failure events on a system but cannot capture the significance of the temporal order of events, which may be critical. In this paper, we propose an extension based on formal definition and use of Priority AND gates that enables representation of event sequences and analysis of temporal relationships in FTA. In addition, we show how this type of temporal analysis can be used in conjunction with a recently proposed method for automated fault tree synthesis to allow accurate failure analyses of system models to be carried out efficiently. The approach is demonstrated on a generic system with a shared backup component. The paper tentatively concludes that this type of temporal FTA can provide a more precise and ultimately more correct insight into the failure behaviour of a system.     

Fuzzy temporal fault tree analysis of dynamic systems

Fault tree analysis (FTA) is a powerful technique that is widely used for evaluating system safety and reliability. It can be used to assess the effects of combinations of failures on system behaviour but is unable to capture sequence dependent dynamic behaviour. A number of extensions to fault trees have been proposed to overcome this limitation. Pandora, one such extension, introduces temporal gates and temporal laws to allow dynamic analysis of temporal fault trees (TFTs). It can be easily integrated in model-based design and analysis techniques. The quantitative evaluation of failure probability in Pandora TFTs is performed using exact probabilistic data about component failures. However, exact data can often be difficult to obtain. In this paper, we propose a method that combines expert elicitation and fuzzy set theory with Pandora TFTs to enable dynamic analysis of complex systems with limited or absent exact quantitative data. This gives Pandora the ability to perform quantitative analysis under uncertainty, which increases further its potential utility in the emerging field of model-based design and dependability analysis. The method has been demonstrated by applying it to a fault tolerant fuel distribution system of a ship, and the results are compared with the results obtained by other existing techniques.     

基于可能性理论的设备故障诊断

基于Ｌ．Ａ．Ｄａｄｅｈ的可能性理论,本文提出了一种设备故障的模糊诊断方法,将其应用于机车发动机的磨损状态识别,可以取得良好的诊断效果     

一种故障树分析的新算法

本论文中，首先引入了ＢＤＤ（ＢｒｉｎａｒｙＤｅｃｉｓｉｏｎＤｉａｇｒａｍｓ－ＢＤＤ）的概念，介绍由故障树到ＢＤＤ转化算法一递归法，及ＢＤＤ进行故障树分析的方法。     

Inferential models and relevant algorithms in a possibilistic framework

We provide a general inferential procedure based on coherent conditional possibilities and we show, by some examples, its possible use in medical diagnosis. In particular, the role of the likelihood in possibilistic setting is discussed and once the coherence of prior possibility and likelihood is checked, we update prior possibilities.     

Introducing validity in fuzzy probability for judicial decision-making

Since the Age of Enlightenment, most philosophers have associated reasoning with the rules of probability and logic. This association has been enhanced over the years and now incorporates the theory of fuzzy logic as a complement to the probability theory, leading to the concept of fuzzy probability. Our insight, here, is integrating the concept of validity into the notion of fuzzy probability within an extended fuzzy logic (FLe) framework keeping with the notion of collective intelligence. In this regard, we propose a novel framework of possibility–probability–validity distribution (PPVD). The proposed distribution is applied to a real world setting of actual judicial cases to examine the role of validity measures in automated judicial decision-making within a fuzzy probabilistic framework. We compute valid fuzzy probability of conviction and acquittal based on different factors. This determines a possible overall hypothesis for the decision of a case, which is valid only to a degree. Validity is computed by aggregating validities of all the involved factors that are obtained from a factor vocabulary based on the empirical data. We then map the combined validity based on the Jaccard similarity measure into linguistic forms, so that a human can understand the results. Then PPVDs that are obtained based on the relevant factors in the given case yield the final valid fuzzy probabilities for conviction and acquittal. Finally, the judge has to make a decision; we therefore provide a numerical measure. Our approach supports the proposed hypothesis within the three-dimensional contexts of probability, possibility, and validity to improve the ability to solve problems with incomplete, unreliable, or ambiguous information to deliver a more reliable decision.     

Distinction between several subsets of fuzzy measures

In this paper, we place several fuzzy measure subsets in relation one with the other. The subsets under study are those corresponding to the definitions of probability measure. Sugeno's g_λ-measure, Shafer's belief function and Zadeh's possibility measure. We study the intersection of these subsets and we show the particular role of Dirac's measures in this comparison. We limit ourself to the case of mappins whose domain is the collection of all subsets of a finite set.Finally, the obtained partial results are summarized in only one figure which shoul clarify the specificity of each of the above definitions.     

Fuzzy cardinality and the modeling of imprecise quantification

The concept of cardinality of a fuzzy set has received attention from several researchers and has been defined in several apparently independent manners. A systematic investigation of this notion is performed which unifies and improves previous attempts. The cardinality of a fuzzy set, viewed as a fuzzy integer, is related to scalar cardinality indices. The closely related question of the probability of a fuzzy event is dealt with. Lastly, the usefulness of fuzzy cardinality for meaning representation of statements or queries involving fuzzy linguistic quantifiers is emphasized.