表决冗余系统可靠度实用计算方法和程序

本文给出表决冗余系统可靠度的实用计算方法和一个通用的ＦＯＲＴＲＡＮ７７计算程序，从而解决了单元数量大的冗余系统的实际计算问题。     

转换开关不完全可靠的热贮备系统可靠性模型

针对n台可靠度负指数分布的设备组成的热贮备系统,其中转换开关的可靠度或者是常数或者是负指数分布的情况,建立了转换开关不完全可靠的热贮备系统可靠性模型。并通过对系统平均寿命的分析,提出n≤4为宜的结论。     

星载偏振成像仪供配电系统可靠性分析

供配电系统是星载偏振成像仪电子学系统的重要组成部分,它不仅要满足将卫星平台提供的一次电源转换成载荷所需的各种二次电源的功能需求,同时还需要满足载荷在轨运行时的高可靠性和长寿命要求。电子元器件的应力分析法是分析电子系统可靠性的一种重要方法,基于应力分析法并根据GJB/Z 299C-2006 《电子设备可靠性预计手册》,对星载偏振成像仪供配电系统各组成部件的电子元器件进行失效率计算,并结合系统结构框图对系统的可靠度进行分析。分析结果表明,采用冷贮备的冗余设计方式可以明显提高系统的可靠度。     

星载有源相控阵天线可靠性建模与分析

针对星载有源相控阵天线可靠性建模不准确问题,研究了天线阵系统的失效判据并提出了一种表决冗余的故障相关系统“树联”可靠性模型。该模型利用树结构的层次关系描述系统内各单元间的关联,将系统正常工作判据等效为每层单元的冗余约束。在此基础上,通过引入条件概率,并以递归的方式给出了系统可靠度的计算方法。同时,还提出了一种基于蒙特卡洛的系统可靠度模拟方法。最后,以某星载有源相控阵雷达天线为例,对模型及算法进行了验证。结果表明,“树联”可靠性模型较传统模型更准确,且解析值与蒙特卡罗仿真结果吻合较好。     

梳状模型再探讨及拓展

研究了单元失效率相同的梳状模型与经典的系统可靠性模型的联系。通过定义不同的损失函数,几类经典可靠性模型中的不可靠度均可统一以梳状模型的任务损失风险表达。给出了含热备份单元和含冷备份单元的梳状模型任务损失风险的表达式,拓展了梳状模型的适用范围。     

可靠性设计、试验与设备

0101818基于结构模型的系统级测试性设计(DFT)技术研究[刊]/钱彦岭//测控技术.—2000,19(9).—12～14(E)0101819开关寿命连续型冷贮备可修系统的可靠性分析[刊]/吴清太//南京航空航天大学学报.—2000.32(5).—556～561(E)对由 n 个同型部件和一个修理设备组成的、开关寿命为连续随机变量的冷贮备可修系统.当部件的工作时间和维修时间以及转换开关的寿命和修理时间均服从指数分布。所有随机变量均相互独立、工作部件的寿命分布与其贮备过多长时间无关、故障部件和转换开关修复后的寿命分布与新部件、新开关的寿命相同的条件下作了研究,建立了该类系统的一般模型,当 n     

基于增强型逐步协商表决的星载计算机容错

文章针对空间环境中的相关瞬态故障，提出了一种新的容错算法－增强型逐步协商表决。增强型逐步协商表决的主要思想是：如果有足够的无故障子系统可用于进行多数表决，系统就进行多数表决；如果无故障子系统很少，系统就以待命冗余的方式运行；如果发生相关瞬态故障，系统就通过卷回机制来克服相关瞬态故障。为了实现增强型逐步协商表决，文章分析了星载计算机的系统状态空间，区分出相关瞬态故障空间，提出了新的系统状态向量形式和     

在定期检修下复杂电子系统的可靠性计算

本文根据冗余设计的复杂电子系统在不维修情况下的可靠度函数，建立在定期检修冗余单元情况下系统可靠度和ＭＴＢＣＦ的精确计算公式，本文最后给出一个实例。     

冷储备单元串联系统可靠性论证

冗余设计是保证产品任务可靠性的有效手段。对于多个相同单元组成的串联系统,为了提高其任务可靠性,可以采用冷储备冗余的设计方法。不同于采用系统备份的旁联设计,采用单元级的冷储备设计在保障高任务可靠性的同时成本更低,也更低于在重量、空间受限的系统中使用。该文采用Markov分析的方法,论证了典型电子设备冷储备单元串联系统的可靠性水平,并对冷储备单元的冗余设计方法的特点进行了分析。     

LD 冗余—长寿命激光发射机初探

本文按照海底光缆通信系统对光发射机的长寿命要求,提出了一种 LD 冗余——多个激光器冷备份自动切换的电路方案。并对无备份和有一个、两个、三个冷备份时的寿命可靠度分别进行了估算,认为最后一种方案是可行的。     

Some Problems of Tradeoff When the Standby Units and Operating Units of a Redundant System Have Different Probabilities of Success

This note considers a redundant system in which the standby units may have a different probability of success than the operating units for a given mission profile. A model is developed so that one can calculate the system reliability for the mission. Furthermore, for the case where reliabilities (probabilities of mission success) of the standby units can be related to the cost of these units, a tradeoff study is made in a few special cases to determine the optimum number of standby components (in the sense of maximizing system reliability) to be installed when there is a fixed sum of money available for the installation of standby units.     

Evaluation of reliability and safety of long-term unmaintained computer systems

In many applications such as critical life-saving systems, safety is an important design issue as well as reliability. Among various commonly-used approaches in the implementation of on-line unrepairable fault-tolerant systems, standby systems achieve the most satisfactory reliability figure, followed by duplex systems, hybrid systems and triple modular redundancy. Nevertheless, the safety figure of duplex systems is superior to that of the standby approach. In this paper, the failure rate of system modules and hard core is predicted by the M1L-HDBK-217E model, and we show that the reliability and safety figure of cold standby systems can be further dramatically improved by increasing the number of spare units. Furthermore, comparative measures such as the reliability improvement factor, the safety improvement factor and the mission time improvement factor are proposed for showing that long-term unmaintained systems have reliability and safety as high as other systems that must be repaired.     

Optimal Design for System Reliability and Maintainability

A complex system consisting of N modules that are logically interconnected for mission success is to be placed in the field for a fixed period of time. For some modules, standby units can be provided, for others this option is not available, but we must select from among several design alternatives differing in cost, weight, and reliability. The problem is to determine simultaneously the module designs and the numbers of standby units to maximize the system reliability, subject to cost and/or weight constraints. Other authors have considered a similar problem for a pure series inter-connection of modules, but we permit the system to be any configuration of modules in series and/or parallel. A dynamic programming model is presented for this problem. The notion of the generalized decomposition operator is used to develop a set of recursive relations. An example is included.     

Reliability Analyses of Combined Voting and Standby Redundancies

There is a trend towards more elaborate architecture of redundancy for ultrareliable systems. When used with discretion, mathematical analyses do provide some useful yardsticks for the system engineer at the conceptual stage of a design. This paper provides a statement of conventional mathematical assumptions and the consequent limitations of the formulae which result from them. More importantly, the paper provides simple formulae for reliability prediction which assist rapid manual appraisals of a large number of possible configurations of majority voters and voter-switches (voter-switches combine voting with standby redundancy). In short order, the decision maker can appraise the potential benefit on system reliability of sophisticated redundancy.     

两部件可修复温储备系统维修策略的改进

考虑由两个可修复元件、一个可修复的转换开关、一位固定的维修人员组成的两部件可修复温储备系统,为了提升系统可靠度,在维修策略上作了改进,提出了一位是固定维修工,两个及以上元件失效时雇佣一位临时工的方法。并建立了策略改进后所相应的Markov过程,通过Laplace变换给出了系统可靠性指标的计算模型,由案例分析获得策略改进后的模型可使系统的可靠性和可用度等指标在原有的基础上得以提高的结果,从而得到该策略的改进是合理和必要的结论。     

Reliability of a Special Class of Redundant Systems

This paper develops equations for predicting the reliability of a special class of redundant systems. Applicable systems include those which operate in a standby mode for a long period of time in anticipation of participation in a single mission. Manual repair is allowed in the standby mode but not in the mission mode. The analysis is also applicable to the single-mission case alone (no standby), where the reliability in this case is evaluated as a function of the reliability state at the start of the mission. The development employs the traditional approach using the concept of failure states and the attendant birth-and-death equations.     

Reliability of Some Modularly Redundant Systems

A mathematical model is established for the reliability of modularly redundant systems with unequal failure rates for the operating and standby units. The failure modes include failures of the active and standby units, three types of switch failures, and failures on system recovery. System reliability is considered for cases of both similar and dissimilar units, and for various restrictions on the failure parameters. It is shown that the most important failure parameters are those related to catastrophic failures, and that putting more reliable units as basic units, which operate initially, is important when switches and recovery are imperfect.     

Reliability and availability analysis of warm standby systems in the presence of chance with multiple critical errors

This paper presents a reliability and availability analysis of k active, N warm standby units in the presence of chance with M multiple critical errors. The system is in a failed state when (N + 1) units have failed (active and/or warm standby units have failed) or one of the multiple critical errors has occurred. Failed units are not repaired but a failed system will be repaired with repair times arbitrarily distributed. The expressions for reliability, availability and steady-state availability are derived.     

验证复杂电子系统任务可靠度的试验方案

阐述了基本可靠性验证试验不能取代任务可靠度验证试验的方案。在很多情况下,系统的基本可靠性验证试验获得通过,但任务可靠性却达不到指标要求;相反,任务可靠性验证试验则可以包含基本可靠性的信息。介绍了同时进行两种验证试验的试验方法和数据处理方法。     

A note on the cost analysis of an n-unit system with spares

This paper deals with the cost analysis of a non-repairable standby system consisting of (n + m) identical units; n-units are needed for the system to function, while the remaining m units are warm standbys. The online and standby units have different constant failure rates. There is no facility for repair. Functions expressing the probability that in (0, t) there are i on-line failures and j standby failures and thereby the reliability of the system. MTTF and the expected profit are obtained. Finally, a numerical example with graphs is also given to highlight important results like the reliability of the system, MTTF and the expected profit.