A novel approach for analyzing the behavior of industrial systems using weakest t-norm and intuitionistic fuzzy set theory

The present work investigates the various reliability parameters of industrial systems in terms of membership and non-membership functions by using α-cut and the weakest t-norm based arithmetic operations on triangular intuitionistic fuzzy sets. As the available information about the constituent components of the system is most of the time imprecise, incomplete, vague and conflicting, the management decisions are based on experience. Thus, the objective of this paper is to quantify the uncertainties that make the decisions realistic, generic and extensible for the application domain. Sensitivity of system performance has also been analyzed for showing the effect of taking wrong combinations of reliability parameters. The obtained results computed by the proposed approach are compared with the existing methodologies. The approach has been illustrated through a case study for supremacy.     

区间三角模糊多态贝叶斯网络可靠性分析方法研究

针对传统系统可靠性分析方法在处理模糊信息方面的不足,建立了基于区间三角模糊贝叶斯网络的多态系统可靠性分析方法。通过区间三角模糊子集来描述根节点故障率;基于区间三角模糊子集,构建了区间三角模糊多态贝叶斯网络模型;研究了区间三角模糊多态贝叶斯网络可靠性分析算法,给出了求解叶节点故障模糊可能性与去模糊根节点后验概率的计算方法。最后,对塔机倾覆事故进行了可靠性分析,验证了该方法的有效性。     

A novel approach for analyzing fuzzy system reliability using different types of intuitionistic fuzzy failure rates of components

This paper addresses the fuzzy system reliability analysis using different types of intuitionistic fuzzy numbers. Till now, in the literature, to analyze the fuzzy system reliability, it is assumed that the failure rates of all components of a system follow the same type of fuzzy set or intuitionistic fuzzy set. However, in practical problems, such type of situation rarely occurs. Therefore, in the present paper, a new algorithm has been introduced to construct the membership function and non-membership function of fuzzy reliability of a system having components following different types of intuitionistic fuzzy failure rates. Functions of intuitionistic fuzzy numbers are calculated to construct the membership function and non-membership function of fuzzy reliability via non-linear programming techniques. Using the proposed algorithm, membership functions and non-membership functions of fuzzy reliability of a series system and a parallel systems are constructed. Our study generalizes the various works of the literature. Numerical examples are given to illustrate the proposed algorithm.     

基于模糊贝叶斯网络的多态系统可靠性分析及在液压系统中的应用

为使贝叶斯网络能够对模糊信息和不确定信息进行处理,提出一种新的基于模糊贝叶斯网络的多态系统可靠性分析方法。该方法将模糊集合理论引入到贝叶斯网络可靠性分析中,考虑部件故障状态、部件故障率的模糊性以及部件间故障逻辑关系的不确定性,使贝叶斯网络具有处理模糊信息的能力。该方法采用模糊数描述系统和部件的故障状态,利用模糊子集描述部件的故障率,运用贝叶斯网络的条件概率表描述部件间的不确定联系。该方法应用到载重车液压悬架系统的可靠性分析实例中,分析结果表明该方法在进行系统可靠性分析时能够充分利用系统的模糊信息和不确定信息,从而提高系统可靠性分析的效率。     

直觉模糊AHP的煤矿“一通三防”安全性研究

主要立足"一通三防"在煤矿生产中的重要性,选取通风安全可靠性、防尘安全可靠性、防瓦斯安全可靠性、防火安全可靠性作为4个一级评价指标,并在此基础上建立了基于直觉模糊层次分析法的煤矿"一通三防"安全综合评估模型。对直觉模糊数表示的综合评价值进行打分排序,并结合实际案例验证其可行性。结果表明,通过该模型的数值计算,可以直观判断煤矿的安全生产状态,达到提前预测预警,减少煤矿生产事故发生的目的。     

概念设计产品的模糊可靠性预测及方案评价

对概念设计产品进行了模糊可靠性预测,将故障树底事件发生可能性的模糊语言描述量化为模糊集的元素。在可靠性预测过程中针对基于模糊集理论的变参数逐点运算模型的不足,利用参数型Hamacher算子建立了定参数逐点运算模型并在此基础上依据设计者的主观判断确定预测结果,提高了分析效率并得到了更合理的结果。利用物理规划进行概念设计方案评价,为概念设计方案评价提供了新的途径。最后用实例说明了上述方法的可行性及合理性。     

凸模型T-S故障树及重要度分析方法

针对故障数据缺乏、故障机理复杂多样等原因导致T-S故障树底事件的失效可能性具有不确定性的问题,以及概率和模糊T-S故障树以及布尔逻辑门故障树适用性的不足,提出凸模型T-S故障树及重要度分析方法：将区间模型引入到T-S故障树分析方法中,利用区间模型描述底事件的失效可能性,提出区间T-S故障树分析方法,解决底事件的失效可能性不易精确获取的问题;在此基础上,引入超椭球模型来界定不确定性参量的取值范围,进而提出超椭球T-S故障树分析方法,解决区间T-S故障树在进行可靠性分析时,分析结果相对保守的问题;进而,定义凸模型T-S故障树的重要度指标,为找到系统的关键环节提供依据;求解出上级事件的失效可能性、底事件的T-S凸模型重要度和T-S凸模型关键重要度,通过与凸模型布尔逻辑门故障树、T-S故障树进行对比,验证所提方法的可行性。最后,给出了组合导航系统可靠性分析实例。     

基于模糊故障树理论卷板机可靠性分析

利用故障树对卷板机的升降工作辊系统进行可靠性分析,考虑到基本事件的发生概率存在不确定性,采用三角模糊数将故障树中基本事件的发生概率模糊化,根据最小割集法的求解对其故障进行定性分析,利用定义和中值法对其故障进行定量分析,建立了基于三角模糊数的故障树分析方法流程,为提高系统的可靠性提供了分析依据。     

太阳翼驱动机构的模糊动态故障树分析

作为航天器重要的组成部分之一的太阳翼驱动机构,故障频发,它的可靠性研究凸显出重要的价值。根据太阳翼驱动机构的组成和工作原理,建立了相应的动态故障树。考虑到现实中太阳翼驱动机构的故障现象、故障状态与故障原因等存在着大量的不确定性,将模糊集理论引入动态故障树分析中,采用三角模糊数表示太阳翼驱动机构故障树的各个底事件的失效参数,将 截集理论与区间运算相结合,对太阳翼驱动机构进行模糊动态故障树分析,从而得到系统的顶事件模糊发生概率与各个底事件的模糊概率重要度,并对模糊概率重要度进行分析,得出太阳翼驱动机构中的关键部件为系统中的轴承及谐波减速器,找到了系统的薄弱环节。     

基于数字积分法的模糊可靠性计算模型

在研究系统的模糊可靠性问题时，对模糊可靠度的计算是一个十分困难的问题。为了解决此问题，提出一种基于数字积分法的模糊可靠性计算模型，它重点解决工程实际中的随机应力0模糊强度模型问题。在此基础上提出一种模糊可靠性的数学运算法则，它可以用来计算机械部件、传感器、电子单元等的模糊可靠性。基于这种计算模型，提出一种计算鱼雷圆柱形壳体模糊可靠性的方法，它为鱼雷可靠性分析建立了一种系统组成单元模糊可靠性的基础。最后通过实例进行了计算分析，计算结果证明这种方法与工程实际是一致的。     

故障树模糊分析方法的研究

对于模糊不确定性信息较多的系统，尤其是处于研制初期的复杂机械系统，如发动机，传统的故障树分析未必能很好地适用。相比之下，故障树模糊分析方法因能考虑专家经验和模糊不确定性信息却非常适用。该研究着重应用模糊算法和非模糊化方法，提出了两种适用范围广、工程性强的故障树模糊分析方法。     

摆动活齿传动系统故障树分析

探讨了摆动活齿传动的故障树分析的一般方法;建立了摆动活齿传动系统的故障树和结构函数,分析说明了系统可靠度的计算,用模糊数表示活齿传动中各事件发生的概率,对摆动活齿传动系统进行了模糊故障树分析。     

基于模糊故障树的主轴箱可靠性分析

利用模糊故障树理论对重型卧式车床主轴箱系统可靠性进行分析.以某重型卧式车床主轴箱为例,通过建立主轴箱故障树,找出故障树顶事件的最小割集;利用模糊理论合理客观地得到主轴箱的故障概率区间;通过对底事件模糊概率重要度的计算,得到顶事件的薄弱环节以及关键事件,从而为主轴箱可靠性设计和可靠性增长指明了方向.结果表明:“润滑不良”为影响主轴箱系统不能正常工作的关键事件.     

加工中心的状态检修系统研究与实现

针对国内某发动机生产企业的设备管理现状,提出一套完整的状态检修系统实施方案。该系统采用基于故障树和FMEA的可靠性分析方法,实现对加工中心的检修优化,并以点检数据为基础,利用模糊数学和灰色理论分别实现了对加工中心的故障诊断和状态评估,最终提供优化的检修决策方案,为发动机制造企业实现设备状态检修提供了技术支持。     

A direct-integration-based structural reliability analysis method using non-probabilistic convex model

In practical structural reliability analysis, there is not only random uncertainty but also fuzzy uncertainty. Aiming at the fuzzy reliability of structure, a novel fuzzy reliability method is proposed based on direct integration method and ellipsoidal convex model. Firstly, the decomposition of fuzzy mathematics principle is used to convert fuzzy reliability model into non-probabilistic reliability model, in which fuzzy variables are converted into interval variables. The upper and lower bounds of interval variables are determined by the possibility distribution function on the membership value. Secondly, multidimensional ellipsoid convex models are constructed to quantify the uncertainty because of the complexity of non-probabilistic reliability. Finally, sigmoid function with adjustable parameter is introduced to direct integration method for approximating the step function, and then direct integration method is used to solve the fuzzy reliability. Numerical examples are investigated to demonstrate the effectiveness of the present method, which provides a feasible way for the structural fuzzy reliability analysis.     

Confidence bounds on component reliability in the presence of mixed uncertain variables

Uncertainties in a physical system can be modeled and analyzed by using probability theory or possibility theory, depending on the amount of information available. In probability theory, uncertain variables are modeled using probability density functions (PDFs) and then propagated through the system to obtain its reliability. In the absence of sufficient data to model a PDF, possibility theory, in which variables are represented using fuzzy membership functions, can be used to propagate uncertainty. However, when dealing with a combination of both probability distributions and fuzzy membership functions, the computational cost involved in estimating the membership function of reliability increases exponentially because one reliability analysis, which is a computationally expensive procedure, is performed at each possibility level to obtain the bounds on the reliability of the structure. To improve the computational efficiency, a technique that uses response surface models and transformations of possibility functions is presented in this paper. The efficiency and accuracy of the proposed methodology is demonstrated using numerical examples.     

Reliability analysis of a phaser measurement unit using a generalized fuzzy lambda-tau(GFLT) technique

Nowadays power consumption is increasing day-by-day. To fulfill failure free power requirement, planning and implementation of an effective and reliable power management system is essential. Phasor measurement unit(PMU) is one of the key device in wide area measurement and control systems. The reliable performance of PMU assures failure free power supply for any power system. So, the purpose of the present study is to analyse the reliability of a PMU used for controllability and observability of power systems utilizing available uncertain data. In this paper, a generalized fuzzy lambda-tau (GFLT) technique has been proposed for this purpose. In GFLT, system components' uncertain failure and repair rates are fuzzified using fuzzy numbers having different shapes such as triangular, normal, cauchy, sharp gamma and trapezoidal. To select a suitable fuzzy number for quantifying data uncertainty, system experts' opinion have been considered. The GFLT technique applies fault tree, lambda-tau method, fuzzified data using different membership functions, alpha-cut based fuzzy arithmetic operations to compute some important reliability indices. Furthermore, in this study ranking of critical components of the system using RAM-Index and sensitivity analysis have also been performed. The developed technique may be helpful to improve system performance significantly and can be applied to analyse fuzzy reliability of other engineering systems.     

滚子活齿行星减速器强度的模糊可靠性设计

本文根据模糊可靠性理论,对滚子活齿行星减速器的强度的模糊可靠性设计原理和方法进行了初步探讨,导出了相应的计算公式,并给出了应用实例。     

大型星载天线展开系统故障树的区间分析方法

针对某周边桁架式大型星载天线进行展开可靠性研究。分析大型星载天线的展开机理,并在对星载天线展开系统故障树分析的基础上,针对传统故障树分析中存在的不确定性难以量化的问题,结合D-S(dempster-shafer)理论和区间概率理论,提出星载天线展开机构故障树区间分析方法,构造失效独立和失效相关情况下故障树区间分析的与门区间算子和或门区间算子,在此基础上对系统的展开可靠度进行分析和预测。可靠性分析的结果表明文中提出的计算模型和分析方法是合理和可行的。     

模糊结构和机械系统的能度可靠性分析方法

模糊系统的可靠性评估是工程中倍受关注的重要问题。结构系统的可靠性与结构的失效模式有关。模糊结构系统失效的可能度取决于失效可能度最大的最危险失效模式。因此，最危险失效模式的识别及对应极限状态方程的建立是模糊结构系统可靠性分析的关键问题。本文基于模糊结构的能度可靠性理论，建立模糊结构和机械系统的能度可靠性分析模型。所提出的模糊结构体系失效模式的枚举准则，可在只需枚举出少量主失效模式的条件下，不漏掉最危险失效模式。算例分析表明文中方法是有效和可行的。