Reliability analysis of k-out-of-n system with load-sharing and failure propagation effect

In complex systems,functional dependency and physical dependency may have a coupling effect.In this paper,the reliability of a k-out-of-n system is analyzed considering load-sharing effect and failure mechanism(FM)propagation.Three types of FMs are considered and an accumulative damage model is proposed to illustrate the system behavior of the k-out-of-n system and the coupling effect between load-sharing effect and FM propagation effect.A combinational algorithm based on Binary decision diagram(BDD)and Monte-Carlo simulation is presented to evaluate the complex system behavior and reliability of the k-out-of-n system.A current stabilizing system that consists of a 3-out-of-6 subsystem with FM propagation effect is presented as a case to illustrate the complex behavior and to verify the applicability of the proposed method.Due to the coupling effect change,the main mechanism and failure mode will be changed,and the system lifetime is shortened.Reasons are analyzed and results show that different sensitivity factors of three different FMs lead to the change of the development rate,thus changing the failure scenario.Neglecting the coupling effect may lead to an incomplete and ineffective measuring and monitoring plan.Design strategies must be adopted to make the FM propagation insensitive to load-sharing effect.

基于混合冗余策略的k-out-of-n:G系统可靠性优化模型

很多对可靠性要求极高的系统通常被设计成k-out-of-n:G结构,然而对该类系统的可靠性优化是一个相当困难的问题。为进一步扩展模型的适用性,提出一种采用混合冗余策略的可靠性优化新模型。该模型首次在k-out-of-n:G系统的可靠性优化中引入混合冗余策略,可以为每个子系统选择(积极、冷备份或混合)冗余策略中的任何一个。首先,基于连续时间马尔可夫链为k-out-of-n:G系统建立精确计算系统可靠性的数学模型。其次,提出一个冗余分配问题和一个工程案例问题,并设计一种伪并行遗传算法进行求解。最后,为评估新模型的性能,通过对提出的两个问题进行数值分析来评估新模型的性能。实验证明,相比以往模型研究,所提新模型得到更高的系统可靠性值,具有良好的应用前景。

k-out-of-n系统机会维护与库存控制多层级优化策略

面向服务型制造的复杂系统维护外包决策需求,针对k-out-of-n:G系统中冗余设备干涉、停机惩罚高昂和备件库存限制的挑战,提出了机会维护与库存控制多层级优化策略(OMICP).在设备层,构建各独立设备衰退模型,通过最小化维护成本率,贯序输出各设备预防维护周期;在系统层,以各设备维护时点为契机,综合考虑库存水平、关停数量和冗余干涉,制定动态组合机会维护策略;在联合层,基于机会维护决策反馈,建模分析备件订购利润结余,制定实时更新库存控制策略.通过服务商承担外包维护下的多层级交互决策,整合复杂系统维护与库存控制耦合关系,优化维护外包服务总成本.算例分析证明,所提OMICP具有复杂决策可行性和成本优化有效性.

基于累积成本限制的k-out-of-n:F系统维护决策

为了在提高系统可靠性的同时有效控制修复成本,以k-out-of-n:F系统为研究对象,提出基于累积修复成本限制策略的维护模型,模型中考虑系统部件之间的失效相关性,根据系统中失效部件的数量m将系统故障分为两类。其中,Ⅰ类故障:系统失效部件数0<m<k,修复方式为最小修复;Ⅱ类故障:系统失效部件数m≥k,系统失效,对系统进行更换。以最小累积修复成本率为目标,采用迭代算法对模型进行数例分析,结果表明所建模型是有效且实用的。

序贯k-out-of-n系统在序约束下参数的假设检验

考虑带有协变量的序贯k-out-of-n模型,假设给定协变量寿命的分布是指数分布族,对指数分布的刻度参数建立对数线性模型,研究在序约束下模型参数的两个假设检验问题,并讨论在序约束下检验统计量的渐近分布为χ^2分布.

Reliability Analysis for the Competing Failure with Probabilistic Failure Threshold Value and Its Application to the k-out-of-n Systems

A method for reliability analysis of the competing failure with the probabilistic failure threshold value not the fixed threshold value is presented, which involves the random shocks and the degradation is independent and dependent respectively. Specifically, for the dependent condition, the effect due to the random shocks on the degradation is considered with a damage factor. In addition, the dependent competing failure model is applied to the reliability analysis of the k-out-of-n systems. Finally, two studied cases are presented to illustrate the proposed method, and the results show the proposed method is reasonable.

K-OUT-OF-N(F)C输油管道系统的可靠性计算

用K -OUT -OF -N(F)C系统来描述输油管道系统 ,利用概率理论和Markov链的有关性质推导出K -OUT -OF -N(F)C输油管道系统可靠度的精确计算公式和近似计算公式 ,并通过算例对精确计算公式和近似计算公式进行了比较 ,得出了近似计算公式的误差比较小 ,可以应用于工程中 ,并且通过数值计算得出n在大于 10时 ,利用近似公式计算K -OUT -OF -N(F)C输油管道系统的可靠度的结论 ,有益于对输油管道系统的可靠性进行合理的、整体性的评价 ,为输油管道的安全运行提供有效理论依据。

可修k-out-of-n:G系统的可靠性分析

用马氏链数学模型研究了可修 k- out- of- n:G系统 ,得到了计算系统的瞬时可用率的方法和计算系统稳态可用率的公式 ,最后以 Internet为例说明了该方法和公式的工程应用。

区间数据观测下k-out-of-n系统剩余寿命的一些年龄性质

考虑第k-1个元件在时刻t或时刻t以前失效的条件下,k-out-of-n系统仍在工作时的剩余寿命,得到了剩余寿命的一些年龄性质.

k-out-of-N系统的随机比较

设 {Xn,n≥ 1}是独立非负随机变量序列 ,N是正整值的随机变量且与 {Xn,n≥ 1}独立 .考虑由寿命为X1,… ,XN 的N个部件组成的k -out -of-N系统 (系统正常当且仅当N个部件中至少k个正常 )的寿命 。

Stochastic comparisons on total capacity of weighted k-out-of-n systems with heterogeneous components

This paper carries out stochastic comparisons on the total capacity of weighted k-out-of-n sys-tems with heterogeneous components.The expectation order,the increasing convex/concave order and the usual stochastic order are employed to investigate stochastic behaviours of sys-tem capacity.Sufficient conditions are established in terms of majorisation-type orders between the vectors of component lifetime distribution parameters and the vectors of weights.Some examples are also provided as illustrations.

可修复与不可修复K-out-of-N:G体系的可靠性瞬态分析

提出了受M个故障模式影响的可修复与不可修复的K-out-of-N:G体系的马尔可夫模型.可修系统的可靠性和平均故障时间可以通过线性微分方程组的数值解得到.瞬时概率的闭型解被用来获得不可修复体系的可靠性和平均故障时间.

基于更新型及最小维护的K-out-of-n:f系统维护策略研究

以k-out-of-n:f系统为研究对象,首先根据失效的部件数量和系统状态,将故障分为第一类故障和第二类故障。在周期性维护策略模型中,对于预防维护周期内的第一类故障采用最小维护进行处理,并在到达预防维护周期时对系统进行预防性维护,对于周期内的第二类故障通过替换使系统恢复正常。在模型基础上,运用更新过程理论,通过建立包含预防维护成本、最小维护成本和故障性维护成本在内的成本函数,导出使长期单位时间期望成本最小的最佳预防维护周期。最后,通过数值算例的分析说明了模型的有效性。

New model for load-sharing k-out-of-n:G system with different components

On the basis of capacity flow model, a new model is developed for a load-sharing k-out-of-n： G system consisting of different components, to describe the increase of the same component＇s failure rates under different loads. All components have exponential life distributions and are nonrepairable in the system. Reliability of load- sharing 2-out- of-3： G system is calculated and some special cases for the system are discussed. The calculation and discussions show that the model is right and practical.

序贯k-out-of-n系统在序约束下参数的估计和算法

本文主要研究带有协变量的序贯k-out-of-n模型.我们假定给定协变量寿命的分布是指数分布,对指数分布的刻度参数建立了对数线性模型.研究了在序约束下模型参数的最大似然估计及最大似然估计量的性质,并且给出了最大似然估计的具体算法并进行了模拟.

Preservation of the NBUCA Class of Life Distributions

The purpose of this paper is to discuss the closure properties of increasing convex average order and NBUCA life distributions. Under the assumption that the units are only independent, characterizations of NBUCA class of life distributions are given. It is shown that NBUCA class is closed under the random maxima and the formation of parallel systems of independent units. As an application of the main results, the behavior of this class is developed in terms of the monotonicity of the residual life of k-out-of n systems given the time at which the （n -k ）-th failure has occurred.

Improving Energy and Power Efficiency Using NComputing and Approaches for Predicting Reliability of Complex Computing Systems

Opting to follow the computing-design philosophy that the best way to reduce power consumption and increase energy efficiency is to reduce waste, we propose an architecture with a very simple ready-implementation by using an NComputing device that can allow multi-users but only one computer is needed. This intuitively can save energy, space as well as cost. In this paper, we propose a simple and realistic NComputing architecture to study the energy and power-efficient consumption of desktop computer systems by using the NComputing device. We also propose new approaches to estimate the reliability of k-out-of-n systems based on the delta method. The k-out-of-n system consisting of n subsystems works if and only if at least k-of-the-n subsystems work. More specificly, we develop approaches to obtain the reliability estimation for the k-out-of-n systems which is composed of n independent and identically distributed subsystems where each subsystem （or energy-efficient usage application） can be assumed to follow a two-parameter exponential lifetime distribution function. The detailed derivations of reliability estimation of k-out-of-n systems based on the biased-corrected estimator, known as delta method, the uniformly minimum variance unbiased estimate （UMVUE） and maximum likelihood estimate （MLE） are discussed. An energy-management NComputing application is discussed to illustrate the reliability results in terms of the energy consumption usages of a computer system with qua（t-core, 8 GB of RAM, and a GeForce 9800GX-2 graphics card to perform various complex applications. The estimated reliability values of systems based on the UMVUE and the delta method differ only slightly. Often the UMVUE of reliability for a complex system is a lot more difficult to obtain, if not impossible. The delta method seems to be a simple and better approach to obtain the reliability estimation of complex systems. The results of this study also show that, in practice, the NComputing architecture improves both energy cost saving and energy efficient living spaces.

多元重尾索赔下的渐近有限时间破产概率（英文）

本文研究进行多线生意的保险公司.在同时面临1阶上象限尾相依重尾索赔的情形下,基于所谓的k-out-of-n破产集,我们得到Radon测度的显示表达并推导出有限时间内部分支线公司破产时的渐近破产概率.我们给出了具体阐释主要结论的数值例子.

System reliability evaluation of long railway subgrade slopes considering discrete instability

This paper develops a dual-indicator discrete method(DDM)for evaluating the system reliability performance of long soil subgrade slopes.First,they are segmented into many slope sections using the random finite element method,to ensure each section statistically contains one potential local instability.Then,the k-out-of-n system model is used to describe the relationship between the total number of sections n,the acceptable number of failure sections m,the reliability of sections R_(sec),and the system reliability R_(sys).Finally,m and R_(sys)are jointly used to assess the system reliability performance.For cases lacking spatial data of soil properties,a simplified DDM is provided in which long subgrade slopes are segmented by the empirical value of section length and R_(sec)is substituted by that of crosssections taken from them.The results show that(1)DDM can provide the probability that the actual number of local instabilities does not exceed a desired threshold.(2)R_(sys)decreases with increasing n or decreasing R_(sec);that is,it is likely to encounter more local instabilities for longer or weaker subgrade slopes.n is negatively related to the horizontal scale of fluctuation of soil properties and positively related to the total length of subgrade slopes L.(3)When L is sufficiently large,there is a considerable opportunity to meet local instabilities even if R_(sec)is large enough.

基于快速离散曲线变换的各向异性虹膜识别

提出了旋转不变技术在决策水平上进行虹膜特征提取和融合后分类的方法,以提高非理想环境条件下的性能。在这项工作中,基于二维(2D)快速离散曲线波变换(FDCT)的方向性虹膜纹理特征被计算出来。该方法将归一化的虹膜图像分为六个子图像。Curvelet变换应用于每个子图像。使用这些curvelet系数的方向能量导出每个子图像的特征向量。这些距离在决策层通过新颖的后分类器k-out-of-n进行融合,降低错误识别率。最后提出的方法在UBIRIS,MMU1和CASIA-Iris V2.0数据库上进行了测试,证明了所提出算法的可行性,并将其与现有虹膜识别算法进行了比较。实验结果表明,该算法可以提高虹膜识别准确率,达到较高的实际应用中的要求。