系统可靠性结构模型的新进展

本文从实际工程可靠性与维修性分析中导出的权联结构,定期检修与间断使用的冗余结构和非独立冗余单元的表决结构等三种新的结构数学模型,适用于对电子,机电系统可靠性与维修性的分析与设计。     

大型相控阵雷达天线阵面的任务可靠性设计

大型相控阵雷达的天线阵面系统复杂,故障模式多样,各模式对雷达工作的影响程度也不同。针对这些特点,文中采用了基于任务可靠性的可靠性预计。同时,通过表决冗余及开展定期检修的方式,来确保天线阵面设备及系统的高任务可靠性。推导了各种典型任务剖面的可靠性数学模型,建立了任务可靠性模型,并对雷达天线阵面进行了可靠性预计,从而为大型相控阵雷达天线阵面的高任务可靠性设计提供了理论依据和技术方法。     

N+K形式冗余备份通信系统的可用度分析

文中利用随机Petri网对n k形式冗余备份通信系统进行了综合分析,分析过程充分考虑了系统的动态变化和工程中的实际情况,建模过程简单直观,而且通过PIPE软件的仿真,得出了通信系统可靠性评价的一系列结果。该方法为工程人员设计系统的配置提供理论依据和数值依据,为促进配置资源的最优组合提供了较好的参考。     

指挥业务组合服务的可靠性研究

本文给出了指挥业务服务可靠性的度量方法,然后对指挥业务组合服务的可靠性评价模型进行了分析,最后提出了一种基于冗余的指挥业务组合服务可靠性计算方法。     

联机检修结构可靠性模型在雷达设计中的应用

联机检修可靠性模型能够充分地发挥冗余结构的潜力,大幅度地提高冗余结构的任务可靠性。为了验证联机检修模型在工程中的应用,结合某军航雷达的设计,对该模型进行了详细的论证;通过在该军航雷达中采用联机检修模型而大大提高了整机的任务可靠性,实现了总体单位的研制任务书要求,对其他型号地面雷达的可靠性设计起到一定的指导作用。     

对《定期检修系统的可靠性建模与仿真》的商榷

商榷论文给出了描述连续工作状态下的定期检修系统的可靠性解析模型和仿真框图,但文中并没有涉及失效单元的检修方式和检修能力,并且没有考虑检修中的备件保障,因此难以正确地反映客观实际.通过示例指出了文中的不合理之处,希望引起相关人员的重视.     

ADS-B系统运行可靠性评价方法

为实现ADS-B系统运行可靠性的综合评价,提出了一种基于T-S模糊神经网络的方法。以平均首次故障时间、平均故障间隔时间、平均维修时间、平均可用度和维修时间率5项可靠性评价指标作为输入向量。利用T-S模糊系统构建可靠性综合评价的非线性映射关系,经神经网络的自适应训练,调整模糊规则和隶属度函数,建立ADS-B系统运行可靠性的综合评价模型。实验仿真与应用情况表明,该方法可行、有效,并具有较高的计算稳定性、精确性和良好的泛化能力,且评价结果客观、准确可靠,可作为提高ADS-B系统运行可靠性的决策依据。     

多媒体网络可靠性分析系统实现

基于MDI的视频质量分析模型,设计并实现了多媒体网络可靠性分析系统。首先,基于RTP/RTCP协议,实现了多媒体网络视频的实时远程传输及播放。然后,将多媒体网络的视频主观评价方法与客观评价方法相结合,提出了一种综合可靠性评价方法,相较于目前的网络可靠性分析方法,综合可靠性评价方法更加全面、可信。最后,通过实验给出了可靠性分析系统的结果。     

网管系统多种运行场景下的模块可靠性

该文针对当前网管系统(NMS)可靠性评价研究中存在的问题,提出了一种分析NMS运行阶段模块可靠性的方法。该方法首先把NMS中使用的定时报活、模块冗余等可靠性措施组合为3种主要运行场景;然后,运用马尔科夫再生随机Petri网对3种场景进行了建模,定量分析了不同运行场景对模块可靠性的影响,并应用模型得到了模块可用度等重要的可靠性指标。实例表明,NMS模块的运行阶段可靠性取决于自身质量和运行场景两方面的因素,可通过配置场景针对性地进行NMS可靠性设计和指标分配。     

基于多因素的Ad Hoc网络连通可靠性仿真方法

移动Ad Hoc网络的连通可靠性对于战场的指挥控制、警察与医疗部门的抢险救灾等众多领域具有重要意义。然而当前的移动Ad Hoc网络连通可靠性评估方法大多建模简单,考虑因素单一,而以OPNET为代表的网络仿真只针对网络普通性能分析而没有可靠性分析。因此,目前缺少一种能够涵盖真实场景中节点移动、无线通信特性和复杂地形环境的移动Ad Hoc网络连通可靠性评价方法。针对此问题提出了多因素模型连通可靠性仿真方法,同时结合可靠性定时标准实验方法给出了系统的移动Ad Hoc网络可靠性仿真实验设计方案。并根据具体移动Ad Hoc网络案例,在OPNET中进行二次开发建模与仿真,验证了该多因素连通可靠性仿真方法的可行性。     

Maintenance of reliable real time systems: Hardware versus software tradeoffs

The maintenance features in a high reliability real time control system form an important component in the total system. It is essential that software and hardware maintenance features function in an effective manner to ensure a high level of reliability in real time systems. Hardware maintenance features include redundant processors, self-checking circuits, diagnostic microcode etc., while software maintenance features include fault recovery programmes, audits, diagnostics etc. In this paper, we examine briefly the relationship of maintenance software to hardware in current high reliability real time systems, and how this relationship is likely to change in the future. Discussion in the paper centres around issues such as: factors that contribute to effective maintenance design; hardware characteristics that affect software; partitioning of maintenance functions between software, firmware and hardware; and current trends in maintenance of real time systems.     

Reliability of a 3-unit cold redundant system with Weibull failure

Redundancy technique is applied to increase the reliability of a system where maintenance or repair is either not possible or is too costly. Reliability of a cold redundant system is always higher than a hot one. Moreover the increase in reliability due to adding of a unit in sequence can always be exactly determined.Literature is full of derivation of reliability expressions of a cold redundant system whose units obey exponential failure density. Due to extreme difficulty in evaluation of integrals involving Weibull density function, few attempts on derivation of reliability of redundant systems have been made. We have here derived reliability of a simple case of a 3-unit cold standby system whose units obey Weibull failure density.     

Architecture and reliability of fault tolerant bitonic sorter

Bitonic sorters are used in a number of telecommunication switching and digital signal processing systems, where any fault in the sorters may spell disaster. Unlike the conventional approach to enhance reliability using redundant sorters, the author presents a sorter with internal redundant sorting elements and evaluates its fault tolerance     

飞行控制计算机余度管理策略研究

为满足系统可靠性指标的要求,采用了余度技术,研制了双通道余度飞行控制计算机.在该研究对象的基础上,进行了一种硬件冗余和软件管理的余度管理策略的研究和设计,提出了多余度信号监控表决算法、基于CAN总线的故障检测机制和系统重构与恢复的方法.故障注入实验表明,样例余度飞行控制计算机在遇到故障时能够实时检测出故障,诊断故障类型,并对故障进行处理,完成系统重构,提高了飞行控制系统的任务可靠性,保证无人机的飞行安全.     

A New Real-Time Reliability Prediction Method for Dynamic Systems Based on On-Line Fault Prediction

While a specific system is in use, its reliability will decrease gradually after the infant mortality period because of the components' degradation, or external attacks. Thus, reliability is a natural characteristic of a system's health, and can be used for condition monitoring & predictive maintenance. This paper introduces a new real-time reliability prediction method for dynamic systems which incorporates an on-line fault prediction algorithm. The factors that may reduce a system's reliability are modeled as an additive fault input to the system, and the fault is assumed to be varying linearly with time, approximately. The time-varying fault is roughly estimated based on a modified particle filtering algorithm at first. Then, as a time series, the fault estimate sequence is smoothed, and predicted by an exponential smoothing method. Mathematical analysis shows that the effects of the system, and measurement noises on the fault estimates are greatly reduced by exponential smoothing, which indicates that the comparatively high accuracy of the fault estimates & predictions is guaranteed. Based on the particle filtering & fault prediction results, the whole system's predictive reliability is computed through a Monte Carlo simulation strategy. The effectiveness of the proposed real-time reliability prediction method is validated by a computer simulation of a three-vessel water tank system.     

Fault tolerance in Clos–Knockout multicast ATM switch

In this paper, we propose a new architecture for multicast ATM switches with fault tolerant capability based on the Clos–Knockout switch. In the new architecture, each stage has one more redundant switch module. If one switch module is faulty, the redundant module would replace the faulty one. On the other hand, under the fault‐free condition, the redundant modules in the second and third stages will provide additional alternative internal paths, and hence improve the performance. The performance analysis shows that the cell loss probability is lower than the original architecture when all modules are fault free, and the reliability of the original architecture is improved. Copyright © 2002 John Wiley & Sons, Ltd.     

基于JTAG的硬件故障注入工具

可靠性是评价容错计算机的重要性能指标之一,评价系统的可靠性在计算机系统的设计及实现阶段都有重要意义,故障注入法是可靠性评测的一种常用方法。在通用的JTAG调试技术基础上,描述了一种针对CPU的硬件故障工具,并通过仿真实验进行了验证。该硬件注入工具基于IEEE标准,只要知道目标芯片的边界扫描链,就可以进行故障注入工作;同时,该工具对目标系统的故障注入工作由硬件完成,对操作系统透明,可以有效地突破操作系统的保护机制。     

航空红外相机成像故障仿真研究

本文基于光学相机成像效应仿真模型，提出了一种航空红外相机典型故障效应仿真方法。在对航空红外相机的光学系统、探测器、电子电路信号对成像效应进行深入仿真的基础上，对不同类型成像故障效应进行了模拟，采用典型故障的成像表现评价指标进行全面验证评价。研究结果表明：基于红外相机成像效应的仿真模型可有效模拟多种故障成像效应，能对装备的使用维护、试验鉴定中的故障的初步分析发挥重要的指导作用。     

Reliability analysis of component-level redundant topologies for solid-state fault current limiter

Experience shows that semiconductor switches in power electronics systems are the most vulnerable components. One of the most common ways to solve this reliability challenge is component-level redundant design. There are four possible configurations for the redundant design in component level. This article presents a comparative reliability analysis between different component-level redundant designs for solid-state fault current limiter. The aim of the proposed analysis is to determine the more reliable component-level redundant configuration. The mean time to failure (MTTF) is used as the reliability parameter. Considering both fault types (open circuit and short circuit), the MTTFs of different configurations are calculated. It is demonstrated that more reliable configuration depends on the junction temperature of the semiconductor switches in the steady state. That junction temperature is a function of (i) ambient temperature, (ii) power loss of the semiconductor switch and (iii) thermal resistance of heat sink. Also, results’ sensitivity to each parameter is investigated. The results show that in different conditions, various configurations have higher reliability. The experimental results are presented to clarify the theory and feasibility of the proposed approaches. At last, levelised costs of different configurations are analysed for a fair comparison.