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Faults modelling is essential to anticipate failures in critical systems. Traditionally, Static Fault Trees are employed to this end, but Temporal and Dynamic Fault Trees are gaining evidence due to their enriched power to model and detect intricate propagation of faults that lead to a failure. In previous work, we showed a strategy based on the process algebra CSP and Simulink models to obtain fault traces that lead to a failure. Although that work used Static Fault Trees, it could be used with Temporal or Dynamic Fault Trees. In the present work we define an algebra of temporal faults (with a notion of fault propagation) and prove that it is indeed a Boolean algebra. This allows us to inherit Boolean algebra’s properties, laws and existing reduction techniques, which are very beneficial for faults modelling and analysis. We illustrate our work on a simple but real case study supplied by our industrial partner EMBRAER. 相似文献
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随机Petri网是一种系统设计和分析工具,它可以对系统进行定性分析和定量分析。为了有效利用随机Petri网进行性能的定量分析,根据随机Petri网模型转换为马尔可夫链的算法,总结并实现了它们之间的转换规则。该转换规则在变迁实施的过程中引入演变规则和合并规则,将随机Petri网模型转换为马尔可夫链。可以利用产生的马尔可夫链对随机Petri网模型的多项性能指标进行定量分析。实验结果表明,转换规则是正确、可行的。 相似文献
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Reliability assessment of industrial processes is traditionally performed with RAMS techniques. Such techniques are static in nature because they are unable to consider the multi-state operational and failure nature of systems and the dynamic variations of the environment in which they operate.Stochastic Hybrid Automaton appears to overcome this weakness coupling a deterministic and a stochastic process and integrating the features of a dynamic system with the concepts of dynamic reliability.At the state of the art, no attempts to enhance a formal RAMS technique with dynamic reliability has been tried, nor a computer-aided tool that plays as expert system has been coded yet.The aim of this paper is to fill this gap with a simulation formalism and a modelling tool able to combine the Dynamic Fault Tree technique and the Stochastic Hybrid Automaton within the Simulink environment. To this aim the MatCarloRE toolbox was adapted to interact with a Simulink dynamic system. The resulting assembly represents an important step ahead for the delivering of a user-friendly computer-aided tool for the dynamic reliability. 相似文献
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基于模糊神经Petri网的故障诊断模型 总被引:1,自引:0,他引:1
Petri网是对具有产生式规则的故障诊断系统的有力建模工具,但其缺乏较强的学习能力.本文以Petri网的基本定义为基础,结合模糊逻辑和Petri网模型,定义了模糊Petri网模型,在此基础上引入人工神经网络技术,给出了人工神经网络的模糊Petri网表示方法,并针对工程机械故障诊断异步、离散等特点,提出并建立了故障诊断的模糊神经Petri网模型及其改进模型.基于模糊神经Petri网的故障诊断系统结合了Petri网和人工神经网络的优点,经过自学习后同时具有很强的推理能力和自适应能力. 相似文献
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FMS是一种结构复杂、投入巨大的系统,利用Petri网在建模方面的图形化、数学化特性可以准确地分析FMS系统的性能。本文结合一个柔性制造系统的具体实例,通过随机高级Petri网进行建模,利用随机高级Petri与随机马尔可夫链的同构关系及成熟的马尔可夫链理论,分析了FMS的多项性能指标。 相似文献
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随机时间Petri网综述 总被引:4,自引:0,他引:4
随机时间Petri网作为一种灵活有力的建模机制,被广泛应用于计算机和通信系统的性能与可靠性评价。综述了随机时间Petri网各主要予类的发展历程与研究现状。首先介绍了随机时间Petrl网的一些基本概念,然后回顾了广义随机Petri网,简要总结了处理状态空间爆炸问题的主要途径,讨论了非马尔科夫随机Petri网及其分析技术,最后详细分析了流体随机Petri网。 相似文献
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联锁逻辑模型的安全性分析 总被引:3,自引:0,他引:3
故障树分析法(FTA)用于静态分析系统失效的可能事件和状态,是分析安全苛求系统的可靠性和安全性的一种有效方法。时间Petri网(TPN)描述具有时序关系的并发系统,用于系统行为的动态建模。但利用时间Petri网无法严格证明其模型是安全的。提出了一种用于时间Petri网模型的安全性分析方法,该方法有效地结合故障树分析法和时间Petri网的各自优点,实际应用于联锁逻辑模型的安全性分析,并对不安全的模型提出修正方案。 相似文献
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Fuzzy rule base systems verification using high-level Petri nets 总被引:3,自引:0,他引:3
Yang S.J.H. Tsai J.J.P. Chyun-Chyi Chen 《Knowledge and Data Engineering, IEEE Transactions on》2003,15(2):457-473
In this paper, we propose a Petri nets formalism for the verification of rule-based systems. Typical structural errors in a rule-based system are redundancy, inconsistency, incompleteness, and circularity. Since our verification is based on Petri nets and their incidence matrix, we need to transform rules into a Petri nets first, then derive an incidence matrix from the net. In order to let fuzzy rule-based systems detect above the structural errors, we are presenting a Petri-nets-based mechanism. This mechanism consists of three phases: rule normalization, rules transformation, and rule verification. Rules will be first normalized into Horn clauses, then transform the normalized rules into a high-level Petri net, and finally we verify these normalized rules. In addition, we are presenting our approach to simulate the truth conditions which still hold after a transition firing and negation in Petri nets for rule base modeling. In this paper, we refer to fuzzy rules as the rules with certainty factors, the degree of truth is computed in an algebraic form based on state equation which can be implemented in matrix computation in Petri nets. Therefore, the fuzzy reasoning problems can be transformed as the liner equation problems that can be solved in parallel. We have implemented a Petri nets tool to realize the mechanism presented fuzzy rules in this paper. 相似文献
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结合了UML状态图的表达特性和Petri网的分析特性,总结出状态图的设计步骤和状态图转化为Petri网的规则,并以国家质检总局科技项目-锅炉仿真系统为背景,对锅炉自动燃烧过程实例进行分析,按照设计步骤和转化规则,最终用Petri网描述出实例,为进一步分析系统特性奠定基础. 相似文献
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针对集装箱码头立体轨道式传送系统网络的复杂结构,采用面向对象随机Petri网(Object-Oriented Stochastic Petri Net,OOSPN)建模方法,简化结构实现层次化建模,并运用随机Petri网进行性能分析。从而检测出系统各个特征状态的执行效率,有效地发现了系统瓶颈,并提出了改进方案。在此基础上,通过WITNESS仿真软件实现码头作业的模拟。结果表明该方法能有效构建和分析集装箱码头立体轨道式传送系统网络复杂系统,并获得其效率指标和统计数据。 相似文献
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Comparison of Hybrid Systems and Fluid Stochastic Petri Nets 总被引:1,自引:0,他引:1
Hybrid Systems are modelsof interacting digital and continuous devices with applicationsin the control of aircraft, computers, or modern cars for instance.Concurrently, Fluid Stochastic Petri Nets (FSPNs) have been introducedas an extension of stochastic Petri nets to model physical systemsthat contain continuous fluid quantities controlled by discretelogic, as well as a means to deal with the possible state explosionof discrete models. Of course, an FSPN is by definition a hybridsystem but in this paper, we compare a general hybrid systemsformalism with FSPN formalism. The conclusion of this paper,suplemented by some examples, is that fluid stochastic Petrinets and hybrid system formalism can be converted from one tothe other. Although there is a price to pay for such a conversion,the conversion can transfer the solution methods from one tothe other and thus help the development of both formalisms. 相似文献
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针对信息物理融合系统(CPS)中的网络安全攻击会导致系统失效的问题,提出一种基于动态故障树的CPS风险建模及分析方法。首先,对动态故障树和攻击树集成建模,构建攻击-动态故障树(Attack-DFTs)模型;然后,分别采用二元决策图和输入输出马尔可夫链给出攻击-动态故障树中的静态子树和动态子树的形式化模型,并在此基础上给出攻击-动态故障树的定性分析方法,即分析网络安全攻击导致系统失效的基本事件路径;最后,通过一个典型的排污系统应用实例对方法的有效性进行验证。案例分析结果表明,所提方法能够分析CPS中由于网络安全攻击导致系统失效的事件序列,有效实现了CPS的综合安全评估。 相似文献