Application of Nonlinear Triangular Fuzzy Fault Tree Algorithm in Predicting Lithium Battery Air Transport Accidents

The traditional triangular fuzzy fault tree prediction model adopts the linear approximation method.Therefore,the accident prediction error is large.Based on the analysis of the error sources and the fuzzy set,the precise calculation method of the event at the top of the fault tree is given.By using the numerical calculation software,an accurate calculation method of nonlinear triangular fuzzy accident prediction was adopted to predict lithium battery air transport fire accidents,and the fuzzy importance of the cause event was calculated.

RELIABILITY ANALYSIS OF THE PRIMARY CYLINDER OF THE 10MN HYDRAULIC PRESS

According to the demand of high reliability of the primary cylinder of the hydraulic press, the reliability model of the primary cylinder is built after its reliability analysis. The stress of the primary cylinder is analyzed by finite element software—MARC, and the structure reliability of the cylinder based on stress strength model is predicted, which would provide the reference to the design.

Reliability Analysis for Complex Systems Based on Dynamic Evidential Network Considering Epistemic Uncertainty

Fault tolerant technology has greatly improved the reliability of modern systems on one hand and makes their failure mechanisms more complex on the other.The characteristics of dynamics of failure,diversity of distribution and epistemic uncertainty always exist in these systems,which increase the challenges in the reliability assessment of these systems significantly.This paper presents a novel reliability analysis framework for complex systems within which the failure rates of components are expressed in interval numbers.Specifically,it uses a dynamic fault tree(DFT)to model the dynamic fault behaviors and copes with the epistemic uncertainty using Dempster-Shafer(D-S)theory and interval numbers.Furthermore,an approach is presented to convert a DFT into a dynamic evidential network(DEN)to calculate the reliability parameters.Additionally,a sorting method based on the possibility degree is proposed to rank the importance of components represented by interval numbers in order to obtain the most critical components,which can be used to provide the guidance for system design,maintenance planning and fault diagnosis.Finally,a numerical example is provided to illustrate the availability and efficiency of the proposed method.

APPLICATION OF FUZZY SET THEORY IN FAULT TREE ANALYSIS

Based on the fuzzy set theory and the expand principle, using fuzzy number as the boundary condition of fault tree analysis, a new method of analyzing fuzzy fault probability of the top event is developed. Fuzzy importance analysis of the basic event is proposed as well. A practical example is given. This method is a new way to solve the obscure problems of fault tree analysis and has great value in engineering practice.

Assessment of gas and dust explosion in coal mines by means of fuzzy fault tree analysis

During the past decade, coal dust and gas explosions have been the most two serious types of disasters in China, threatening the lives of miners and causing significant losses in terms of national property. In this paper, an evaluation model of coal dust and gas explosions was constructed based on a fuzzy fault tree by taking the Xingli Coal Mine as a research site to identify the risk factors of coal dust and gas explosions.Furthermore, the hazards associated with such explosions were evaluated for this particular coal mine.After completing an on-site investigation, the fuzzy probabilities of basic events were obtained through expert scoring, and these expert opinions were then aggregated as trapezoidal fuzzy numbers to calculate the degrees of importance of all basic events. Finally, these degrees of importance were sorted. According to the resulting order, the basic events with higher probabilities were determined to identify key hazards in the daily safety management of this particular coal mine. Moreover, effective measures for preventing gas and coal dust explosions were derived. The fuzzy fault tree analysis method is of high significance in the analysis of accidental coal mine explosions and provides theoretical guidance for improving the efficiency of coal mine safety management in a scientific and feasible manner.

Methodology for reliability allocation based on fault tree analysis and dualistic contrast

Reliability allocation is a difficult multi-objective optimization problem. This paper presents a methodology for reliability allocation that can be applied to determine the reliability characteristics of reactor systems or subsystems. The dualistic contrast,known as one of the most powerful tools for optimization problems,is applied to the reliability allocation model of a typical system in this article. And the fault tree analysis,deemed to be one of the effective methods of reliability analysis,is also adopted. Thus a failure rate allocation model based on the fault tree analysis and dualistic contrast is achieved. An application on the emergency diesel generator in the nuclear power plant is given to illustrate the proposed method.

Analysis of Syetem Reliability in Manufacturing Cell Based on Triangular Fuzzy Number

Due to lacking of test-data and field-data in reliability research during the design stage of manufacturing cell sys- tem.The degree of manufacturing cell system reliability research is increased.In order to deal with the deficient data and the un- certainty occurred from analysis and judgment,the paper discussed a method for studying reliability of manufacturing cell system through the analysis of fuzzy fault tree,which was based on triangular fuzzy number.At last,calculation case indicated that it would have great significance for ascertaining reliability index,maintenance and establishing keeping strategy towards manufac- turing cell system.

Numerical Simulation to Reliability Analysis of Fault-Tolerant Repairable System

In the traditional method for the reliability analysis of fault-tolerant system,the system structure is described by means of binary decision diagram (BDD) and Markov process,and then the reliability indexes are calculated.However,as the size of system augments,the size of state space will increase exponentially.Additionally,Markov approach requires that the failure and repair time of the components obey an exponential distribution.In this study,by combining dynamic fault tree (DFT) and numerical simulation based on the minimal sequence cut set (MSCS),a new method to evaluate reliability of fault-tolerant system with repairable components is proposed.The method presented does not depend on Markov model,so that it can effectively solve the problem of the state-space combination explosion.Moreover,it is suitable for systems whose failure and repair time obey an arbitrary distribution.Therefore,our method is more flexible than the traditional method.At last,an example is given to verify the method.

Fault Tree Analysis of CNC Machine Tool Based on BDD Technology

CNC machine tool is a large complex system which contains both mechanical and electrical components.As one of these components,the spindle is crucial for the performance of CNC machine tool.To improve the quality of CNC machine,the reliability of spindle was evaluated in this paper using a fault tree analysis(FTA)method.The FTA method is a set of calculation methods based on Boolean algebra.However,it is difficult to analyze a large and complex fault tree with inaccurate results and low efficiency as well as the complexity of time and space.Both of them will result in the so-called "combinatorial explosion".To overcome this problem,the analysis method based on binary decision diagram(BDD)was introduced in our works,and a sorting method about bottom events was also recommended which can reduce the size of the BDD effectively.

故障树和模糊贝叶斯网络在管廊运维风险评估中的应用研究

地下综合管廊是城市的生命线,一旦出现问题就会对人们生命财产安全造成巨大损害。为了系统地分析管廊运维风险,建立了基于模糊贝叶斯网络的风险评估框架。首先,通过分析管廊运维风险源与风险形成的原因以确定风险事件和风险类别;其次,建立管廊运维风险故障树来梳理风险因素之间的逻辑关系,将故障树映射为贝叶斯网络;最后,结合专家模糊评价,构建地下综合管廊运维风险评估模型。案例分析结果显示:中间事件“火灾、爆炸”与“危害气体浓度过高”的发生概率较高。敏感性分析结果显示:“运维人员操作和维护不当”是导致管廊运维风险发生的根本事件,因此需要制定严格管理措施及规范,加强对运维人员的素质培训,以降低管廊运维过程中各种风险的发生概率。

基于故障树和贝叶斯网络的管廊运维风险评估

城市地下综合管廊在运维过程中事故时有发生,为了量化管廊运维风险并分析关键风险因素,提出一种基于故障树和模糊贝叶斯网络的城市地下综合管廊运维风险评估方法。在综合考虑管廊风险因素的基础上构建故障树模型,将其映射为贝叶斯网络。基于ALARP准则划分风险因素状态等级,根据模糊数和模糊子集计算底事件的发生概率,利用最大似然估计法求解中间事件的条件概率,构建管廊运维风险贝叶斯网络模型,精准评估城市地下综合管廊运维风险。结果表明:所评估的管廊运维过程风险等级为High的概率为28%,接近30%的风险阈值,因此需要及时对管廊风险进行管控。该方法能够科学、合理地评价风险水平并确定关键因素,可为管廊运维安全保障和管理提供参考。

智能船舶机舱设备健康状态评估技术及应用

针对船舶机舱设备健康状态评估方法和应用进行分析,并进行系统优化设计。引入故障树分析方法和多参数模糊评估方法,设计实现了船舶机舱设备健康状态评估系统。以某型号柴油机实验数据为输入,构建样本数据集,对系统的主要功能进行测试验证,验证结果表明,系统状态识别率达到90%以上,系统在柴油机主机健康平稳性评估方面取得了较好的效果。研究提出的船舶机舱设备的健康状态评估优化设计方案可为后续机舱设备健康状态管理提供参考。

基于T-S模糊故障树的驱动电机冷却系统可靠性分析

车用驱动电机液压冷却系统存在故障机理不确定等问题。本文应用模糊数描述其故障概率和故障程度,建立驱动电机冷却系统的T-S模糊故障树模型,计算系统模糊可能性,分析各部件的概率重要度和关键重要度,找出影响系统可靠性的关键部件。

故障树自动建树及分析软件的实现

故障树分析(Fault Tree Analysis)在系统可靠性评估中起着至关重要的作用。然而,作为故障树分析的核心故障树(FT)的构建,传统构建故障树的方法存在耗时长且容易出错等缺点。为了解决这些问题并应对复杂系统自动建造故障树的困难,该文提出一种基于元部件模型及系统结构模型的规范化描述方法,并以此为基础,通过建立元部件模型库、复杂标识符库,设计出故障树自动建树及分析软件,实现系统结构模型搭建、自动建树、复杂结构识别处理及可靠性分析过程的全自动化。详细阐述了故障树自动建树软件自动建树及分析的基本步骤,并通过一个简化的汽车ABS系统应用实例验证了该软件的有效性和可行性。实例应用结果表明,该故障树自动建树及分析软件不仅能够实现自动构建和分析故障树,提高工作效率,而且能够识别处理具有复杂结构的故障树,对复杂系统的自动建树及可靠性分析的推广具有重要意义。

基于故障树和贝叶斯网络的履带车辆行星变速机构可靠性分析

行星变速机构作为履带车辆传动系统的核心部件,其可靠性直接影响履带车辆的正常运行。以履带车辆行星变速机构为研究对象,基于实测试验结果建立故障树,将故障树转化为贝叶斯网络(Bayesian Network,BN)模型,并考虑行星变速机构正常、普通故障、严重故障3种状态进行可靠性分析。研究结果表明,行星变速机构失效概率为89.34×10^(-8)h^(-1),其工作400 h的可靠度为0.99964,符合设计要求;利用贝叶斯网络双向计算的功能,可知当行星变速机构发生失效,由主轴断裂或摩擦片烧蚀、翘曲、断裂或齿轮疲劳断齿引起的可能性较大。为后续装备检修、改进设计提供理论依据。

基于模糊故障树的某高炮无线电引信安全评估

针对引信系统长期贮藏造成的性能下降、作用过程环境复杂、内部结构失效等情况,和传统的Bell故障树分析方法受限于二元的故障描述状态以及与或关系的限制,提出一种基于模糊故障树的引信安全性评估方法。对模糊故障树进行顶事件概率计算和底事件重要度分析,体现出引信系统故障机制和事件联系的模糊性和事件发生的时序性。利用该评估方法对某小口径高炮无线电引信在预定的解除保险和解除隔离流程开始前引信作用故障树进行实例分析,并与传统Bell故障树分析结果进行对比。结果表明:模糊故障树计算所得的失效率为2.1×10-9,Bell故障树计算所得的顶事件概率值为1.2×10-9,两者为同一数量级,且模糊故障树的重要度分析更加快速和高效,能更加科学地进行引信安全性评估和故障树诊断。

基于故障树分析法的某控制系统故障与可靠性研究

针对复杂卫星载荷控制系统高可靠性提升问题,聚焦系统故障潜在原因,提出一种基于量化底事件与顶事件重要度解析的故障树分析方法。以卫星载荷控制系统设计原理及功能为基础,利用故障树分析法定义故障树顶事件,查找故障原因,确定与底事件之间的逻辑关系,构建故障树;利用布尔代数方法确定故障树最小割集,对故障树底事件进行定性分析;通过最小割集失效率对顶事件进行定性分析,调整单一底事件的质量参数,对底事件与顶事件重要度依赖关系进行量化。研究结果表明,故障树能直观显示系统存在的故障原因,主控芯片故障、时钟信号异常、上位机复位通道故障等为影响系统可靠性的主要故障因素,可根据量化底事件对顶事件故障的影响程度,实现对产品设计、生产、调试、运行过程中潜在故障的预先排查。

考虑不确定性情况下的故障树重要度分析方法及应用

为了度量底事件发生概率不确定性对顶事件的影响程度,在建立故障树概率组成函数的基础上,基于矩独立重要性测度提出了考虑底事件发生概率不确定性情况的故障树重要度分析方法。以某飞机结冰探测系统为例,利用所提出的重要度方法分析了底事件发生概率不确定性对该系统故障的影响程度,设计者可根据重要度结果更有针对性地开展分析与设计,同时也验证了所提方法的合理性。

SMA驱动尿道阀可靠性的蒙特卡罗仿真分析

形状记忆合金(SMA)驱动尿道阀是应对尿道功能障碍设计的机电装置,若临床应用一旦发生失效,将被迫取出更换。为研究尿道阀的可靠性,依据尿道阀组成原理建立了尿道阀故障树和可靠性数学模型,提出了一种基于蒙特卡罗法的尿道阀仿真算法,仿真分析了尿道阀的可靠性指标。实验结果表明:该仿真算法简单有效,尿道阀平均寿命达10000次的失效概率为0.012。该仿真算法也可为克服膀胱功能障碍的SMA驱动人工逼尿肌系统可靠性设计提供理论指导。