失效单调关联系统的条件存活元件数量

单调关联系统在可靠性,生存分析和其他生命科学中扮演着非常重要的角色.在本文中,我们考虑了n中取(n-k+1)系统中存活元件的数量,假设在时刻t时存活的元件至少有(n-m+1)个,且系统在时刻t处于失效状态.在此条件下,我们计算系统中存活元件数量为i(i=n-m+1,…,n-k)的概率,从而获得了其可靠性与几个随机性质.此外,我们将结果扩展到具有绝对连续可交换元件的一般单调关联系统.     

单调关联系统模糊可靠度函数的性质

应用可靠性和模糊数的基本理论,给出了单调关联系统的模糊可靠度的定义,并讨论了单调关联系统的模糊可靠度函数的性质。     

单调关联系统的条件失效元件数量

Coherent systems are very important in reliability,survival analysis and other life sciences.In this paper,we consider the number of failed components in an(n-k+1)-out-of-n system,given that at least m(m相似文献   

一类不同可靠度部件非单调关联系统的最优设计

本文对航天系统中应用广泛的一类典型的非单调关联系统（ｎ中取ｒ至ｓ系统）进行了可靠性分析,比较了目前对系统进行可靠度计算的几种方法的优劣,详细研究了给定ｒ,ｓ及不同部件可靠度ｐ_ｉ的情况下,使系统效益达到最高的条件ｎ值的最优配置问题,并结合国外某类航天系统工程中的计算机集成系统给出了一个数值例子,并用面向 Ｗｉｎｄｏｗｓ的 ＶＢ６． ０实现了一个图形交互的求解系统最优配置和系统可靠度的软件．     

多状态可靠性系统动态signature及其剩余寿命分析

系统signature是分析系统可靠性的一个强有力的工具。本文研究了多状态系统的动态signature。Signature概念被拓展到多维的情形,并将其应用于两状态元件下多态关联系统的分析,得到系统在每一状态下的联合生存函数的表达式,探究了系统在时刻的动态signature,为处于工作状态的多状态系统在时刻t接受检查,发现其处于l(t)状态并且恰好已发生了q(t)次元件失效,分别给出了两状态元件多态关联系统动态signature及其剩余寿命的表达式。     

基于随机滤波法的滚动轴承剩余寿命预测

使用剩余寿命描述滚动轴承的潜在状态,基于随机滤波方法建立滚动轴承的剩余寿命预测模型,给出了建模步骤和方法,并讨论了模型的参数估计问题.实例分析结果验证了该建模方法和参数估计方法的有效性和准确性.     

一类并联系统的剩余寿命和平均剩余寿命

研究了n个独立但不同分布的元件构成的一类并联系统的剩余寿命和平均剩余寿命,即在t_1时刻有l个元件失效,第k个元件的寿命恰好是t_2(0≤lkn,0≤t_1t_2),系统在t_2时刻仍然工作的条件下并联系统的可靠性函数和平均剩余寿命.     

基于分散型和扩散型随机序对几种寿命分布类的刻画

本文基于分散型和(或)扩散型随机序，利用随机变量的剩余寿命给出了寿命分布类ILR，IFR，DMRL和IFR(2)及其对偶类的刻画．作为主要结果的一个应用，用k／n-系统的剩余寿命对IFR和DMRLS及其对偶类进行了刻画．这些结果拓宽和加强了文献中已有的结果．     

离散时间下马氏可修系统剩余寿命的极限分布

本文对离散马氏可修系统剩余寿命的极限分布进行了研究，指出此分布为几何分布，同时，对一些特殊的马氏可修系统给出其极限分布的参数，并给出了算例。     

一类混合单调算子的不动点定理

运用锥理论与迭代方法,讨论了在较弱条件下一类混合单调算子的不动点的存在唯一性,所得结果是某些已有结果的本质改进和推广.     

排队系统平稳等待时间的性质

讨论了M/G/1排队系统平稳等待时间的随机序关系及利用Mathematica 4.0软件探讨了爱尔朗排队系统Er/M/1（r≤6）的平稳等待时间的分布。     

Stochastic Comparisons and Dependence among Concomitants of Order Statistics

Let (X_i, Y_i) i=1, 2, …, n be n independent and identically distributed random variables from some continuous bivariate distribution. If X_(r) denotes the rth ordered X-variate then the Y-variate, Y_[r], paired with X_(r) is called the concomitant of the rth order statistic. In this paper we obtain new general results on stochastic comparisons and dependence among concomitants of order statistics under different types of dependence between the parent random variables X and Y. The results obtained apply to any distribution with monotone dependence between X and Y. In particular, when X and Y are likelihood ratio dependent, it is shown that the successive concomitants of order statistics are increasing according to likelihood ratio ordering and they are TP₂ dependent in pairs. If we assume that the conditional hazard rate of Y given X=x is decreasing in x, then the concomitants are increasing according to hazard rate ordering and are dependent according to the right corner set increasing property. Finally, it is proved that if Y is stochastically increasing in X, then the concomitants of order statistics are stochastically increasing and are associated. Analogous results are obtained when the variables X and Y are negatively dependent. We also prove that if the hazard rate of the conditional distribution of Y given X=x is decreasing in x and y, then the concomitants have DFR (decreasing failure rate) distributions and are ordered according to dispersive ordering.     

Bondesson's functions in reliability theory

Bondesson's functions in reliability theory are shown to be related to a recursive sequence of probability distributions. These are the ‘higher-order’ versions of the mean remaining lifetime in an equilibrium renewal process. Based on these functions, classes of distribution functions can be defined. This paper will investigate these classes and place Bondesson's work in the content of the other work done in reliability theory. Connections are made with the decreasing variance residual lifetime class and stochastic ordering. Copyright © 1999 John Wiley & Sons, Ltd.     

A bayesian approach to inference for monotone failure rates

In reliability theory, the notion of monotone failure rates plays a central role. When prior information indicates that such monotonicity is meaningful, it must be incorporated into the prior distribution whenever inference about the failure rates needs to be made. In this paper we show how this can be done in a straightforward and intuitively pleasing manner. The time interval is partitioned into subintervals of equal width and the number of failures and censoring in each interval is recorded. By defining a Dirichlet as the joint prior distribution for the forward or the backward differences of the conditional probabilities of survival in each interval, we find that the monotonicity is presenved in the posterior estimate of the failure rates. A posterior estimate of the survival function can also be obtained. We illustrate our method by applying it to some real life medical data.     

On optimal polling policies

In a single-server polling system, the server visits the queues according to a routing policy and while at a queue, serves some or all of the customers there according to a service policy. A polling (or scheduling) policy is a sequence of decisions on whether to serve a customer, idle the server, or switch the server to another queue. The goal of this paper is to find polling policies that stochastically minimize the unfinished work and the number of customers in the system at all times. This optimization problem is decomposed into three subproblems: determine the optimal action (i.e., serve, switch, idle) when the server is at a nonempty queue; determine the optimal action (i.e., switch, idle) when the server empties a queue; determine the optimal routing (i.e., choice of the queue) when the server decides to switch. Under fairly general assumptions, we show for the first subproblem that optimal policies are greedy and exhaustive, i.e., the server should neither idle nor switch when it is at a nonempty queue. For the second subproblem, we prove that in symmetric polling systems patient policies are optimal, i.e., the server should stay idling at the last visited queue whenever the system is empty. When the system is slotted, we further prove that non-idling and impatient policies are optimal. For the third subproblem, we establish that in symmetric polling systems optimal policies belong to the class of Stochastically Largest Queue (SLQ) policies. An SLQ policy is one that never routes the server to a queue known to have a queue length that is stochastically smaller than that of another queue. This result implies, in particular, that the policy that routes the server to the queue with the largest queue length is optimal when all queue lengths are known and that the cyclic routing policy is optimal in the case that the only information available is the previous decisions.This work was supported in part by NSF under Contract ASC-8802764.     

Stochastic comparisons of component and system redundancies with dependent components

Under the assumption of dependent identically distributed components and redundant (spares) components, the problem of stochastic comparison of component and system redundancies have been considered. This study has been carried out under the criteria of the likelihood ratio ordering, the reversed failure rate ordering, the failure rate ordering and the usual stochastic ordering.     

A test for the bidirectional stochastic order with an application to quality control theory

A test for the bidirectional stochastic ordering is developed in this paper. The main properties of such a test are investigated. The asymptotic distribution of the statistic of the test is obtained under conditions which allow the construction of critical regions with a specific level of significance. It is also proved that the test is consistent on the whole set of alternatives. An application of such a test to quality control theory is developed.