基于随机Petri网的装甲车辆综合电子系统可靠性研究

由于装甲车辆综合电子系统具有耦合性强、动态离散和复杂度高的特点,其难以采用静态故障树方法进行系统可靠性分析,针对这一难题,运用动态故障树方法对系统可靠性进行了分析判别,并运用随机Petri网建立了故障树的仿真模型。以某型车辆为例,通过仿真实验得出了综合电子系统的故障率和可用度指标的动态变化曲线,其分析结果为系统可靠性与测试性设计提供了理论参考。     

稳态随机过程激励下基于首次超越破坏的结构优化设计

把结构系统动力可靠性分析与最优化设计结合起来 ,以结构系统的最小质量为目标函数 ,给出了考虑在平稳随机过程激励下多自由度线性系统总的可靠性的结构优化设计方法。运用谱分析理论 ,推导了结构系统在平稳随机过程激励下响应的统计特征 ,同时结合首次超越破坏的Possion模型计算结构系统的可靠性 ,最终采用广义乘子法得到结构系统设计变量的最优值。计算结果表明该方法是可行的     

动态系统可靠性分析的新概念

传统可靠性分析的概念只能描述静态逻辑关系,不能满足现代复杂动态系统可靠性分析的需要。在给出动态系统状态空间结构和结构函数的基础上,提出失效序列和失效丛的概念描述动态系统的故障模式,这一概念扩展了传统可靠性分析的概念,将割集、蕴含集等作为其在静态情形的特例。给出动态系统部件的概率重要度、结构重要度以及关键重要度的概念,用实例对提出的有关概念进行了说明。     

Dynamic signatures and their use in comparing the reliability of new and used systems

The signature of a system with independent and identically distributed (i.i.d.) component lifetimes is a vector whose ith element is the probability that the ith component failure is fatal to the system. System signatures have been found to be quite useful tools in the study and comparison of engineered systems. In this article, the theory of system signatures is extended to versions of signatures applicable in dynamic reliability settings. It is shown that, when a working used system is inspected at time t and it is noted that precisely k failures have occurred, the vector s [0,1]^n‐k whose jth element is the probability that the (k + j)th component failure is fatal to the system, for j = 1,2,2026;,n ‐ k, is a distribution‐free measure of the design of the residual system. Next, known representation and preservation theorems for system signatures are generalized to dynamic versions. Two additional applications of dynamic signatures are studied in detail. The well‐known “new better than used” (NBU) property of aging systems is extended to a uniform (UNBU) version, which compares systems when new and when used, conditional on the known number of failures. Sufficient conditions are given for a system to have the UNBU property. The application of dynamic signatures to the engineering practice of “burn‐in” is also treated. Specifically, we consider the comparison of new systems with working used systems burned‐in to a given ordered component failure time. In a reliability economics framework, we illustrate how one might compare a new system to one successfully burned‐in to the kth component failure, and we identify circumstances in which burn‐in is inferior (or is superior) to the fielding of a new system. © 2009 Wiley Periodicals, Inc. Naval Research Logistics, 2009     

飞机系统安全性指标的Petri Net分配方法

为解决动态故障树抽象而不利于交流的问题,利用Petri Net直观、易用且适用范围广的优点,提出基于Petri Net的飞机系统安全性指标分配方法。通过整理安全性指标及其相关的可靠性指标,选取失效率作为安全性指标,对比动态故障树及Petri Net建模方法,选取后者建立静态逻辑变迁和动态逻辑变迁的Petri Net指标分配模型。在此基础上,提出考虑严酷等级的系统安全性指标分配方法,经过算例分析,构建Petri Net层次系统故障模型进行指标分配。结果表明,分配值均在相应安全性指标内,该方法能够克服动态故障树法不直观、等分配法分配过于粗糙等缺陷,为飞机安全性设计与评估提供参考。     

基于模糊理论的武器系统可靠性分析和评价

武器系统可靠性是指在规定条件下和规定时间内完成规定功能的能力。传统的可靠性计算方法是基于概率论的,其失效概率通常应根据第一手的数据。然而,实际上不可能收集到足够的数据,一般是依靠专家的经验来判断估计,这类判断通常与模糊性密切相关。本文基于可靠性理论和模糊数学的原则和方法,建立了一套计算串联系统和并联系统的模糊可靠度的计算公式。应用模糊数对武器装备系统单元可靠性予以模糊评价,并采用模糊可靠性计算模型,对武器系统可靠性进行模糊分析和计算。通过对一高炮武器系统的应用分析,证明了该方法的可行性。     

某履带车辆同步器工作过程仿真及磨损寿命预测

以Virtual．LabMotion为平台，建立同步器同步过程动力学模型，通过仿真对不同换挡力下的同步时间和同步后车速进行了研究。以摩擦学理论为基础，结合摩擦磨损实验，预测同步器的磨损寿命，为同步器的优化设计和提高传动系统可靠性提供了理论依据。     

Optimal redesign decisions through failure rate estimates

To reduce the time-to-market of newly developed systems, manufacturers increasingly adopt strategies where systems are brought to market while system field reliability is still uncertain. These systems are typically sold under performance-based contracts, which incentivizes potential customers to invest in them despite reliability uncertainty. Such contracts make the manufacturer (partly) responsible for the availability of the system. Subsequently, when field reliability is lower than anticipated, the manufacturer may choose to redesign the system to avoid high contract penalties. Redesign is a costly effort which may substantially increase field reliability. Deciding when to redesign is challenging, especially because the initial failure rate estimate by the system's engineers is refined over time as failure data accrues. We propose a model that endogenizes the failure rate updating to analyze this tactical redesign decision. We study additive and multiplicative redesigns and show that the optimal policy has a control limit structure. We benchmark our optimal policy against a static counterpart numerically, and conclude that basing redesign decisions on the updated estimate of the failure rate can substantially reduce costs.     

Reliability growth of repairable systems

This paper considers the problem of modeling the reliability of a repairable system or device that is experiencing reliability improvement. Such a situation arises when system failure modes are gradually being corrected by a test-fix-test-fix procedure, which may include design changes. A dynamic reliability model for this process is discussed and statistical techniques are derived for estimating the model parameters and for testing the goodness-of-fit to observed data. The reliability model analyzed was first proposed as a graphical technique known as Duane plots, but can also be viewed as a nonhomogeneous Poisson process with a particular mean value function.     

基于Bayes理论的固有可用度定时截尾试验方案

为解决小子样条件下进行产品固有可用度试验验证的问题,基于Bayes理论,提出了一种固有可用度定时截尾试验方案．该试验方案在假设故障间隔时间和修复时间均服从指数分布的前提下,将现场试验分为同时进行的可靠性和维修性定时截尾试验2个部分,要求在利用验前试验信息的基础上,使本次试验获得的验后分布还可以作为下一次现场试验的验前分布,提高了试验数据的利用率,具有较好的经济效益．     

火炮炮闩击发机构可靠性强化试验技术

为提高炮闩的试验效率和可靠性,将可靠性强化试验理论引入其可靠性研究中。以火炮炮闩为强化试验载体,基于虚拟样机技术对击发机构磨损失效进行强化试验研究,依据受力分析确定了增大击针簧刚度的强化试验技术,通过仿真试验和分析,结果表明机构磨损量强化系数随强化应力水平的提高而变大,所确定的强化试验技术加快了零部件失效进程,有利于缩减可靠性试验的时间,为可靠性强化试验在装备机械系统中的应用提供理论和技术支撑。     

考虑载荷作用次数的多失效模式扭力轴灵敏度分析

机械构件的不同的失效模式之间具有一定的相关性,而且随机载荷作用次数对机械构件的可靠性有一定程度的影响。因此对机械构件进行可靠性灵敏度分析时,需要充分考虑其不同失效模式和载荷作用次数的影响。通过运用顺序统计量理论考虑载荷多次作用以及多种失效模式条件下机械构件可靠性及可靠性灵敏度的变化规律,运用随机摄动理论和四阶矩技术,建立一种考虑载荷作用次数的多失效模式机械构件可靠性灵敏度分析数值方法的应力强度干涉模型。在随机变量前四阶矩已知的情况下,结合灵敏度分析的梯度算法,推导出关于随机变量均值和方差的灵敏度计算公式。以某履带车辆底盘扭力轴为例进行计算,得到其可靠度随载荷作用次数、随机变量均值和方差而改变的可靠性灵敏度变化曲线,为扭力轴的可靠性优化提供一定的理论依据。研究成果可以推广到相关机械可靠性灵敏度设计和结构优化领域,具有非常重要的实用意义。     

更新理论在机械系统可靠性计算中的应用

耗损型的机械系统的可靠性随着工作时间的增加而变得越来越差。对机械系统的可靠性进行预测和分配或采取相应的维修策略以缩短系统停机时间和减少系统维修费用,是一个需要解决的问题。作者以更新理论作为基础知识,建立了已工作过一定时期的机械系统在未来一段任务时间内的可靠性计算模型,为解决该问题提供了理论依据。     

舰船机械设备备件保障决策分析——可靠性分析

针对典型的舰船机械设备系统,运用故障树分析等现代可靠性理论分析方法,结合系统设备的技术性能分析、非电产品的结构和故障特点以及运行管理实际情况,研究系统设备、部件的故障机理,故障模式和故障影响效应,明确导致设备、部件故障的原因及发生模式。应用FTAS故障树分析软件包对其进行了定性、定量分析,获得了以概率结构事件、最小割集等形式表达的系统设备、部件故障对系统故障的作用模式,并对系统故障概率随时间的变化进行了拟合检验及评价了系统可靠性,为确定在指定远航任务期(90天)内所需的备品备件决策提供依据。     

运行和修复同时进行的固有可用度定时截尾试验方案

针对如何设计一个试验以完成检验系统固有可用度、平均故障间隔时间和平均修复时间等3个指标参数的问题,将试验分为同时进行的可靠性和维修性定时截尾试验2个项目,假设运行时间和修复时间均服从指数分布,且可靠性和维修性试验方案已知,提出了一种固有可用度定时截尾试验方案．该试验方案通过合理选择累积运行时间和累积修复时间,同时满足检验3个指标参数的承制方和使用方风险,可完成对3个指标参数的检验．     

作战飞机可靠性与维修性仿真模型

通过故障树分析建立了作战飞机仿真逻辑关系。在修正线性同余法的基础上获得了随机数模型。在各设备故障发生状态和修复状态识别的基础上,建立了可靠性维修性仿真模型,确定了作战飞机在仿真过程中的工作状态,并根据故障模式影响分析预计了设备故障对作战飞机的影响。最后以F/A-18为例进行可靠性维修性仿真,获得了实时的故障信息和修复信息,验证了仿真模型的可行性。     

天基信息支援下装备战场抢修有色Petri网模型研究

对天基信息支援下装备战场抢修活动过程进行了探索,运用Petri网建模工具建立了天基信息支援下装备战场抢修有色Petri网模型,将组织结构图、功能图和信息流动流程图集于一身,实现了系统的静态结构和动态过程的统一。模型直观、易于理解,对模型运行规则进行了详细说明,有利于仿真编程的实现。通过模型的深入研究,能够加深对天基信息支援下装备战场抢修规律的认识,进一步提高装备战场抢修能力。     

Outsourcing warranty repairs: Dynamic allocation

In this paper we consider the problem of minimizing the costs of outsourcing warranty repairs when failed items are dynamically routed to one of several service vendors. In our model, the manufacturer incurs a repair cost each time an item needs repair and also incurs a goodwill cost while an item is awaiting and undergoing repair. For a large manufacturer with annual warranty costs in the tens of millions of dollars, even a small relative cost reduction from the use of dynamic (rather than static) allocation may be practically significant. However, due to the size of the state space, the resulting dynamic programming problem is not exactly solvable in practice. Furthermore, standard routing heuristics, such as join‐the‐shortest‐queue, are simply not good enough to identify potential cost savings of any significance. We use two different approaches to develop effective, simply structured index policies for the dynamic allocation problem. The first uses dynamic programming policy improvement while the second deploys Whittle's proposal for restless bandits. The closed form indices concerned are new and the policies sufficiently close to optimal to provide cost savings over static allocation. All results of this paper are demonstrated using a simulation study. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2005     

基于UML的装甲装备主动式保障系统建模研究

摘要：为将主动式保障先进理念应用于装甲装备保障过程,采用UML系统建模理论和方法,在分析装甲装备保障主要业务内容的基础上,通过系统需求分析建模和系统分析与设计建模,构建装甲装备主动式保障系统用例模型、对象类静态模型、动态交互模型和状态模型,以及体系结构模型,明确装甲装备主动式保障系统的结构功能与运行流程,为系统仿真与评估、演示验证等后续研究奠定基础．     

Network reliability assessment in a random environment

In this paper we consider networks that consist of components operating under a randomly changing common environment. Our work is motivated by power system networks that are subject to fluctuating weather conditions over time that affect the performance of the network. We develop a general setup for any network that is subject to such environment and present results for network reliability assessment under two repair scenarios. We also present Bayesian analysis of network failure data and illustrate how reliability predictions can be obtained for the network. © 2003 Wiley Periodicals, Inc. Naval Research Logistics 50: 574–591, 2003