可修复系统任务可靠度的 fiducial 界限

一、前言对于不可修复的系统的可靠度的置信界限的讨论已有许多文章,无论是经典法,还是Bayes 法等都有若干结果.对于可修复系统的某些统计分析文章,70年以来也逐渐增多起来,逐渐为人们所关心.Ascher 自1968年以来陆续发表了许多文章,对可修复系统提出了“坏如旧”的新概念,并提出采用非平稳 Poisson 过程的模型来描述可修复系统的失效过程.同时还有许多人对非平稳 Poisson 过程以及 Weibull 过程等的统计分析工作也得到了许多结果.本文所讨论的问题是:对可修复系统可靠度和任务可靠度给出 fiducial 严格的界限和近似的界限.本文还讨论了如何利用可修复子系统的观察数据,得到串联系统可靠度和任务可靠度的 fiducial 界限.     

模糊参数系统可靠度隶属函数的确定方法

利用模糊数与模糊值函数的结构元计算方法研究一类具有单元模糊失效率的系统,分析和讨论模糊参数系统的可靠性计算。本文提出求解系统模糊可靠度及其隶属函数表达形式的三种方法,并给出并联系统、串联系统、串-并联系统、并-串联系统的模糊可靠度及其隶属函数,利用这些方法也可以类似地解决其他具有模糊失效率的较复杂的系统可靠度计算问题。     

Weibull分布可靠度的Bayes置信下限

木文用Bayes方法处理Weibull分布元件可靠度和串联系统可靠度的置信下限,同时给出了一些数值计算结果。     

多元指数分布下的串联结构系统可靠度估计

本文探讨由k个相关元件组成的串联结构系统的可靠度计算与估计问题。当元件的随机强度服从多元指数分布,随机应力为相互独立的指数分布时,导出了可靠度表达式并提出它的一种估计量。当k=2时,本文还证明了该估计量是系统可靠度的相合渐近正态估计。     

可修复系统任务可靠度的置信界限

§1.前言近些年来,对可修复系统的统计分析的文章逐渐增多,尤其 Ascher(1968)的一系列文章中所提出的“坏如旧”的新概念以来,逐渐得到了人们的注意,对非平稳 Poisson 过程以及 Weibull 过程的统计推断的文章也逐渐增多.本文所讨论的问题是,对可修复系统任务可靠度如何给出相应的置信下限.本文仅利用观察时间内系统的失效次数,通过非平稳 Poisson 过程模型来得到系统可靠度和任务可靠度的置信下限,以利用子系统数据得到系统可靠度和任务可靠度的置信下限.     

三状态串、并联系统的优化分配方法

给出了单目标、单约束下三状态串联、并联系统中由选取重要度来提高系统可靠度的有效优化模型及算法,并进行了实例验证.     

Weibull元件串联系统可靠度的最优置信限

本文的主要任务是在一定的试验条件下,基于失效个数的数据,作串联系统可靠度的推断.§1 试验结果分析和观察值空间的分割考察串联成系统的 n 种元件.设第 i 种元件的寿命服从 Weibull 分布,即     

由 Weibull 子系统数据综合的系统可靠度的置信下界限

§1.前言以往对系统可靠度的置信区间估计方法,主要是利用各个子系统的寿命试验的数据,通过系统的可靠性结构模型,进行可靠性综合的方法来得到系统可靠度的置信区间估计.关于这方面的若干情况可参阅文章[1]的概况介绍.从所查阅到的文献来看,主要是各子系统的寿命试验数据为成败型的或是指数分布类型的情况,至于各子系统的寿命分布是Weibull 分布的情况的文章较少,主要原因是,问题解决的困难和计算上产生的困难等,甚至于无法计算,不得不采用 Monte-Carlo 方法.本文中所讨论的问题,是 Weibull 子系统的情况,其方法的计算困难程度可以得到改善.     

串联系统多参数广义不确定度传递模式与多反馈控制

将多参数广义不确定度的概念引入串联系统参数不确定度的传递问题中,建立了串联系统多参数广义不确定度传递模型,该模型不仅揭示了参数不确定度在传递过程中的变化情况,传递细节表明传递矩阵元素对最后的传递结果有重要影响.文中阐述了传递矩阵的特征以及各个子系统在串联系统中的主次作用.针对串联系统建立了多参数广义不确定度多反馈控制模型,提出了针对单个系统、两个子系统、多个子系统多个层次的反馈控制模型.模型的提出从理论上说明了当对子系统传递矩阵进行修正时,输出参数不确定度的变化及其上界的面积范数,为工程实际提供了一个良好的理论模型支撑.     

具有关闭准则的三部件系统的可靠性模型分析

<正> 1.模型假定和状态假设本文研究如图1所示的系统。关于该系统作如下的假定: (1)系统是由A子系统和B子系统串联而成的。其中A由一个部件组成,B是由     

Pooling设计在数控机床可靠性方面的应用

利用随机pooling设计的理论和方法,建立了数控机床可靠性筛选的定量分析数学模型,在统计分析观察工作时间段的基础上,可以筛选出可靠性差的数控机床,为数控机床的改进,产品质量的提高,提供理论依据.     

Decentralized model-reference adaptive control for a class of uncertain large-scale time-varying delayed systems with series nonlinearities

In this paper, the problem of model-reference adaptive control for large-scale time-varying delayed systems with series nonlinearities is investigated. By applying the theory of variable structure control, we propose an adaptive controller, which is both memoryless and decentralized, to derive the error subsystem between the local model state and plant state to zero. The proposed variable structure control is able to ensure the stability of a sliding manifold of the composite system even though the control input is nonlinear. The main difficulty for handling the effects of interconnected terms is well solved by a new proposed adaptation mechanism. Finally, a numerical example is illustrated to demonstrate the validity of the derived controller.     

Optimal control of impulsive switched systems with minimum subsystem durations

This paper presents a new computational approach for solving optimal control problems governed by impulsive switched systems. Such systems consist of multiple subsystems operating in succession, with possible instantaneous state jumps occurring when the system switches from one subsystem to another. The control variables are the subsystem durations and a set of system parameters influencing the state jumps. In contrast with most other papers on the control of impulsive switched systems, we do not require every potential subsystem to be active during the time horizon (it may be optimal to delete certain subsystems, especially when the optimal number of switches is unknown). However, any active subsystem must be active for a minimum non-negligible duration of time. This restriction leads to a disjoint feasible region for the subsystem durations. The problem of choosing the subsystem durations and the system parameters to minimize a given cost function is a non-standard optimal control problem that cannot be solved using conventional techniques. By combining a time-scaling transformation and an exact penalty method, we develop a computational algorithm for solving this problem. We then demonstrate the effectiveness of this algorithm by considering a numerical example on the optimization of shrimp harvesting operations.     

An adaptive design to assess the reliability of the pyrotechnic control subsystem in opening the solar array

The pyrotechnic control subsystem plays an important role in opening the solar array of a satellite. Assessing the reliability of the subsystem requires determining the level of a control factor that is needed to cause the desired response and energy output with high probability. A two-phase adaptive design to estimate the level of interest is proposed and studied. The convergence of the design is obtained. A simulation study shows that the estimate is very close to its population value and is robust to the initial guess of the design. As an application, the design is used to assess the reliability of a real pyrotechnic control subsystem.     

Cost analysis on renewable full-service warranties for multi-component systems

This paper presents a novel warranty policy named ‘full-service warranty’ (FSW) for repairable multi-component systems under which the failed component(s) or subsystem(s) will be replaced, in addition, a (perfect) maintenance action will be performed to reduce the chance of future system failure, both free of charge to consumers. Such a policy is desirable for both consumers and manufacturers since consumers receive better warranty service compared to the traditional free repair policy, at the same time, manufacturers may enjoy increase in sale as well as cost-saving due to improved product reliability by the maintenance action. Under the renewable FSW policy, from manufacturers’ point of view, cost models for complex systems with series, parallel, series–parallel (s–p) and parallel–series (p–s) structure are developed. Exact expressions for the first and second centered moments of warranty cost per product sold are obtained. Sensitivity analysis is performed based on a numerical example.     

A Hybrid Particle Swarm Optimization Algorithm for the Redundancy Allocation Problem

The Redundancy Allocation Problem generally involves the selection of components with multiple choices and redundancy levels that produce maximum system reliability given various system level constraints as cost and weight. In this paper we investigate the series–parallel redundant reliability problems, when a mixing of components was considered. In this type of problem both the number of redundancy components and the corresponding component reliability in each subsystem are to be decided simultaneously so as to maximise the reliability of system. A hybrid algorithm is based on particle swarm optimization and local search algorithm. In addition, we propose an adaptive penalty function which encourages our algorithm to explore within the feasible region and near feasible region, and discourage search beyond that threshold. The effectiveness of our proposed hybrid PSO algorithm is proved on numerous variations of three different problems and compared to Tabu Search and Multiple Weighted Objectives solutions.     

模糊有限状态机的一些性质

讨论模糊有限状态机的一些代数性质,得到模糊有限状态机在同态作用下子系统(强子系统)的前像仍是子系统(强子系统),证明若两个模糊有限状态机之间存在满足一定条件的同态映射时,前一个模糊有限状态机是强连通的(循环的),则后一个模糊有限状态机也是强连通的(循环的),且若这个同态是强满同态,则其中一个模糊有限状态机是完全的当且仅当另一个模糊有限状态机是完全的。对模糊有限状态机的积与原来的模糊有限状态机的完全性、强连通性、循环性、交换性等关系也进行讨论,得到一些结果。     

组合RK-Rosenbrock方法及其稳定性分析

１．引言 在研究和设计宇航飞行器时,常常会遇到刚性大系统,他们具有特殊结构,系统的解分量有的变化很快,而有的变化很慢。我们可将其分解成两个耦合的子系统;其中（１）式为刚性子系统,（２）式为非刚性子系统。 由于子系统（１）是刚性的,因而整个系统也是刚性的,所以需要采用适合于求解刚性方程的隐式或半隐式方法来求解。但是,在很多情况中,刚性方程组（１）仅占整个方程组的很小一部分,而且右函数相当简单,因而整个右函数计算量主要集中在非刚性方程组（２）上。另一方面,这种对整个方程组采用同一个数值积分方法来处理的…     

Scheduling flexible machining and assembly systems

Most scheduling papers consider flexible machining and assembly systems as being independent. In this paper, a heuristic two-level scheduling algorithm for a system consisting of a machining and an assembly subsystem is developed. It is shown that the upper level problem is equivalent to the two machine flow shop problem. The algorithm at the lower level schedules jobs according to the established product and part priorities. Related issues, such as batching, due dates, process planning and alternative routes, are discussed. The algorithm and associated concepts are illustrated on a number of numerical examples.