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.

Reliability Analysis of Hydraulic System of Anchor Drilling Rigs Based on Fuzzy Fault Tree

Considering that the fault phenomenon of the power head cannot feed under actual working conditions,fuzzy mathematics theory is introduced into fault tree analysis(FTA)according to the structural characteristics of hydraulic system of anchor drilling rigs in this paper.The triangle fuzzy number is used to describe the fault probability of the basic event,the fuzzy probability importance of the basic event is calculated,and the basic events are sorted by comparing the magnitude of the fuzzy probability importance.The results show that the gear wear of auxiliary oil pump,suction phenomena of gear pump,wear and leakage of No.1 and No.3 pumps are the key factors leading to power head failure.In order to improve the overall reliability of the hydraulic system,fault diagnosis and maintenance decisions provide a theoretical basis.

Risk Assessment of Deep-Water Horizontal X-Tree Installation

Due to the high potential risk and many influencing factors of subsea horizontal X-tree installation,to guarantee the successful completion of sea trials of domestic subsea horizontal X-trees,this paper established a modular risk evaluation model based on a fuzzy fault tree.First,through the analysis of the main process oftree down and combining the Offshore&Onshore Reliability Data(OREDA)failure statistics and the operation procedure and the data provided by the job,the fault tree model of risk analysis of the tree down installation was established.Then,by introducing the natural language of expert comprehensive evaluation and combining fuzzy principles,quantitative analysis was carried out,and the fuzzy number was used to calculate the failure probability of a basic event and the occurrence probability of a top event.Finally,through a sensitivity analysis of basic events,the basic events of top events significantly affected were determined,and risk control and prevention measures for the corresponding high-risk factors were proposed for subsea horizontal X-tree down installation.

Fuzzy fault tree analysis of roller oscillating tooth gear drive

Conventional fault tree and reliability analysis do not reflect the characteristics of basic events as non stationary and ergodic process. To overcome these drawbacks, theory of fuzzy sets is employed to run fault tree analysis(FTA) of roller oscillating tooth gear drive(ROTGD), the relative frequencies of basic events are considered as symmetrical normal fuzzy numbers, from the logical relationship between different events in the fault tree and fuzzy operators AND and OR, fuzzy probability of top event is solved. Finally, an example is given to demonstrate a real ROTGD system.

Fuzzy Fault Tree Analysis for Fault Diagnosis of Cannula Fault in Power Transformer

Being one of the most expensive components of an electrical power plant, the failures of a power transformer can result in serious power system issues. So fault diagnosis for power transformer is highly important to ensure an uninterrupted power supply. Due to information transmission mistakes as well as arisen errors while processing data in surveying and monitoring state information of transformer, uncertain and incomplete information may be produced. Based on these points, this paper presents an intelligent fault diagnosis method of power transformer using fuzzy fault tree analysis (FTA) and beta distribution for failure possibility estimation. By using the technique we proposed herein, the continuous attribute values are transformed into the fuzzy numbers to give a realistic estimate of failure possibility of a basic event in FTA. Further, it explains a new approach based on Euclidean distance between fuzzy numbers, to rank the basic events in accordance with their Fuzzy Importance Index.

Analytical Model and Algorithm of Fuzzy Fault Tree

In the past, the probabilities of basic events were described as triangular or trapezoidal fuzzy number that cannot characterize the common distribution of the primary events in engineering, and the fault tree analyzed by fuzzy set theory did not include repeated basic events. This paper presents a new method to analyze the fault tree by using normal fuzzy number to describe the fuzzy probability of each basic event which is more suitably used to analyze the reliability in safety systems, and then the formulae of computing the fuzzy probability of the top event of the fault tree which includes repeated events are derived. Finally, an example is given.

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.

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.

Fuzzy Fault Diagnosis of a Diesel Engine Non-start

The diesel locomotive plays an important role in the field of transport, and the engine maintenance work is the prerequisite and gnarantee for the locomotive normal working. In this paper, we first establish the fault tree model of locomotive engine 16V240ZJ on the basis of engine non-start as the top event. Then we combines the fitzzy mathematics the- ory and fault tree analysis method for failure diagnosis of 16V240ZJ engine＇s abnormal start-up. We obtained the fuzzy probability curve and top events probability confidence interval by analyzing the fuzzy fault tree qualitatively and quantitatively. It provides a fuzzy analysis basis for solving the problem of 16V240ZJ engine＇s abnormal start-up.

FUZZY PETRI NET FOR FAULT DIAGNOSIS

Because of the stochastic property of fault occurrence and fuzziness offault phenomenon, machine fault diagnosis technique in use, such as fault tree analysis,cause consequence tree method, etc., cannot exactly describe the properties of fault phe-nomenon and coherence of fault space. In this paper, based on the theory of generalPetri net, fault tree technique and theory of fuzzy set, a theory system of fuzzy Petri net(FPN) suitable for fault diagnosis is established, which is applied to an example of faultdiagnosis for FMS. This method has the properties of of rbjectivity, strong expressionability, easy inference, etc., which can solve the problems of stochastic property andfuzziness of fault.

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。

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L-R型模糊数的原棉库火灾事故树分析

根据现场实际状况的统计并依据专家经验所提供的模糊信息,在对原棉库发生火灾事故构建事故树的基础上,通过运用系统工程的模糊事故树理论中的尖型隶属函数,对原棉库火灾事故进行了模糊可靠性分析,得出了其发生事故的模糊概率可能性分布;并对各个基本事件的结构重要度进行了分析,确立了影响系统的最主要因素,为预防火灾事故的发生以及对系统进行安全分析提供了新的方法和途径。

基于L-R模糊数的综放工作面瓦斯爆燃火灾事故树分析

瓦斯爆燃是矿井火灾的诱发因素之一,由于瓦斯特殊的物理化学性质和赋存条件导致其爆燃形式与煤自燃有许多不同之处.从瓦斯爆燃的三要素入手,结合综放面瓦斯爆燃事故的特点,建立了基于瓦斯爆燃的火灾事故树,在基本事件概率不清楚的情况下,应用模糊数学理论将基本事件概率看作L-R模糊数,对事故树分析得出各个事件的概率值,为矿井防火提供更加科学的参考依据.

基于模糊综合评价的水下采油树结构可靠性分析

针对水下采油树结构可靠性分析,提出一种基于模糊综合评价理论的水下采油树结构可靠性分析方法。首先,通过分析不同厂家水下采油树构型,确定水下采油树的典型结构构型及组成,分析水下采油树在运行过程中所受的外载荷;其次,采用专家打分以及模糊综合评价法求得故障树底事件失效率,通过定量分析求解顶事件失效率、可靠度及可靠寿命曲线等可靠性指标;最后,对故障树进行重要度分析及失效率变化对系统结构可靠性的影响,结果表明:“树本体内磨损”的关键重要度最高,对系统结构可靠性的影响最大,是结构中的薄弱环节,应予以关注。研究成果可为水下采油树结构的风险评估提供技术参考,对水下采油树的设计制造提供一定的指导意义。

基于AHP-模糊综合评价的海上风机基础状态评估

为掌握服役时期的海上风机基础状态并对海上风机基础状态进行评估,提出一套结合故障树分析(Fault Tree Analysis,FTA)法、层次分析(Analytic Hierarchy Process,AHP)法和模糊综合评价法的海上风机基础状态评价模型。针对导管架式海上风机基础,考虑海洋腐蚀和海底冲刷,通过p-y曲线法模拟桩-土相互作用,在风浪流载荷的作用下进行动力响应分析,采用故障树对其失效模式进行分析,确定评价指标,构造判断矩阵计算指标权重,运用模糊综合评价法对各指标和整体进行评价。该模型结合各评价方法的优点,使评价结果更有说服力,可为海上风电场运行维护管理提供技术参考。

煤矿预警信息发布影响因素重要度分析

矿山安全生产态势日益严峻,提升预警信息发布的效果是增强煤矿企业应急信息软实力的关键环节。因此,需要深入了解煤矿预警信息发布的影响因素并进行重要度分析。首先,提出改进的模糊故障树分析方法,通过对实地调研访谈结果进行扎根分析,挖掘煤矿预警信息发布的影响因素,并将其转化为故障树的事件,以此构建煤矿预警信息发布失效故障树;然后,基于专家打分和模糊故障树,对煤矿预警信息发布失效因素进行重要度分析和排序;最后,结合定量和定性分析结果,提出提升煤矿预警信息发布有效性的改进建议。结果表明:煤矿预警信息有效发布的影响因素是信息制作、发布方式、传播主体、响应联动和效果评估,重要度最高的基本事件是响应联动维度的井上井下沟通不畅。该评价过程有机结合了定性和定量两种方法,可为煤矿提高预警信息发布效果提供改进思路。

长螺旋钻机成桩混合料堵管的模糊故障树分析

在钻探工程施工过程中,不可避免地会出现机械故障。采用故障树分析其原因是常用的方法之一。但工程施工中,往往数据不足或不注意保存这些数据,实际应用时难以赋值,只能进行定性分析。针对工程施工机械出现故障的模糊性和不确定性,用模糊数描述底事件的发生概率,提出一种基于三角模糊数的工程施工机械故障树分析方法。该方法通过专家、现场技术人员及操作人员的经验构造三角模糊数描述各底事件发生的概率区间,通过计算三角模糊数的中位数重要度,按重要度大小对故障原因排序,作为制定预防措施的依据。最后将其应用于长螺旋钻机成桩混合料堵管的原因分析,按模糊重要度对故障有针对性地制定预防措施。结果表明:重要影响因素排序与现场技术人员及操作人员的定性分析与判断相符。

Optimization of a dynamic uncertain causality graph for fault diagnosis in nuclear power plant

Fault diagnostics is important for safe operation of nuclear power plants(NPPs). In recent years, data-driven approaches have been proposed and implemented to tackle the problem, e.g., neural networks, fuzzy and neurofuzzy approaches, support vector machine, K-nearest neighbor classifiers and inference methodologies. Among these methods, dynamic uncertain causality graph(DUCG)has been proved effective in many practical cases. However, the causal graph construction behind the DUCG is complicate and, in many cases, results redundant on the symptoms needed to correctly classify the fault. In this paper, we propose a method to simplify causal graph construction in an automatic way. The method consists in transforming the expert knowledge-based DCUG into a fuzzy decision tree(FDT) by extracting from the DUCG a fuzzy rule base that resumes the used symptoms at the basis of the FDT. Genetic algorithm(GA) is, then, used for the optimization of the FDT, by performing a wrapper search around the FDT: the set of symptoms selected during the iterative search are taken as the best set of symptoms for the diagnosis of the faults that can occur in the system. The effectiveness of the approach is shown with respect to a DUCG model initially built to diagnose 23 faults originally using 262 symptoms of Unit-1 in the Ningde NPP of the China Guangdong Nuclear Power Corporation. The results show that the FDT, with GA-optimized symptoms and diagnosis strategy, can drive the construction of DUCG and lower the computational burden without loss of accuracy in diagnosis.