冗余磁盘阵列的故障容错分析

本文在介绍冗余磁盘阵列(RAID)的故障容错机理之后,着重研究了设备故障对RAID系统可靠性的影响.其平均持续正常工作时间和系统在线修复设备故障容许的平均间隔时间的计算结果表明,只要在一定的容许时间内替换或修复故障磁盘,系统可保持持续正常工作状态.     

面向IMA平台的离散事件演化树仿真分析方法

为解决具有时序相关、功能依赖、多态性、部件数量多等特点的IMA平台在可靠性分析中的困难,提出了一种离散事件演化树仿真分析方法,通过将IMA平台运行过程中的随机故障事件建立成离散故障事件序列,从而驱动系统状态的不断演化,利用故障事件演化树分析离散故障事件对系统状态的影响,通过建立系统多状态集合和大样本观测评估IMA平台在不同时刻处于各个系统状态的概率。该离散事件演化树仿真分析方法可实现IMA平台可靠性多态定量分析,为设计提供理论数据依据。     

开关寿命0-1型修理工多重休假的Gnedenko系统

研究了修理工可进行多重休假的Gnedenko系统,转换开关不完全可靠,开关寿命型,假定部件的寿命和转换开关的维修时间服从指数分布,部件的修理时间和修理工的休假时间服从一般连续型分布,通过使用补充变量法和广义马尔可夫过程方法,得到了系统的可靠度的Laplace变换、首次故障前平均时间、稳态可用度和稳态故障频度等重要可靠性指标。     

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     

一类多状态连续n中取k(G)系统的可靠性计算

为了计算多状态连续厅中取后（G）系统的可靠性，引入4个定理，将满足引理的多状态系统转换为二元状态系统。分别推导了多状态线形连续k／n（G）系统和环形连续k／n（G）系统的可靠性计算公式。证明了固定k值增加一个新部件，若部件可靠性独立同分布，线形和环形系统可靠性均增加；若部件可靠性独立但不同分布，环形系统存在一个极值，新增加部件可靠性大于这个极值时得到的新系统可靠性增加，反之系统可靠性下降。     

可修复网络稳态可用度分析

本文提出了可修复网络稳态可用度的数学分析方法。通过证明得出不可修复网络的可靠性多项式适用于可修复网络的可用度，只需相应地把部件的可靠度改为部件的可用度，把部件的不可靠度改为部件的不可用度     

关于可修复系统的MTBF和MTTR

在可修复系统中，可用性作为一种可靠性测度，其指标可用度是基本的；然而从实际应用角度来说平均无故障工作时间和平均修复时间有时显得更为重要，却又往往难以得知，本文首次提供了计算一般的ＭＴＢＦ和ＭＴＴＲ的有效公式，此系统具有负指数分布失效和修复时间部件。     

飞机电源配电线路故障在翼测试系统的设计研究

飞机电源系统的配电线路安全直接影响着飞机上电气设备的工作安全。飞机供电线路阻值以及故障保护时间是重要性能参数,反映了线路的导电性和可靠性。基于LabVIEW开发的飞机电源配电线路故障在翼测试系统实现了配电线路、跳开关和连接件等多种线路连接元素的总等效阻值测试,诊断回路导通性故障;并通过人机交互界面按需设置模拟飞机线路过载或短路故障,测试线路故障保护时间和I~2t保护曲线,获取跳开关性能状态。该测试系统在不影响飞机原有线路构型情况下模拟线路故障并实现在翼测试,可快速诊断线路导通性及保护器件性能状态,具备多通道拓展功能,对飞机电源系统故障诊断研究具有参考价值。     

光缆监测系统技术及应用

传统的光缆维护中光缆中断后故障定位和修复时间比较长。光缆监测系统可以实时监测光缆性能及隐患,发生故障时能迅速确定故障的位置,大大节省修复时间。对监测的数据进行分析,还能掌握光缆的缓慢劣化情况,预报光缆隐患,变被动维护为主动维护。介绍了光缆监测系统的工作原理、研究了几种监测方式及相应优缺点和应用范围、主要部件的性能指标、典型应用案例以及取得的经济效益。     

一种考虑部件冷备冗余的可靠性仿真方法

在考虑部件冗余情况下,通过分析系统部件的状态与系统最小割集之间的关系,研究了部件故障对系统状态的影响;建立了系统的仿真模型,根据系统完成任务的情况,得到了系统可靠性与平均失效时间的统计值,旨在为系统可靠性的设计提供依据.     

An inspection model with minimal and major maintenance for a systemwith deterioration and Poisson failures

A new condition-based maintenance model for a system, subject to deterioration-failures and to Poisson-failures, is presented. After an inspection, based on the degree of deterioration, a minimal maintenance or a major maintenance is performed, or no action is taken. Deterioration failures are restored by major repair; Poisson failures are restored by minimal repair. Major maintenance or major repair restores the system to “good as new” while minimal maintenance restores the system one stage. Generalized stochastic Petri Nets are used to represent and analyze the model, which represents a condition-based maintenance strategy. Based on maximization of the system throughput, an optimal inspection policy within this strategy and optimal inter-inspection time are obtained. The effects of inspection, maintenance and repair parameters are investigated. For a given inspection parameter, a 3-region diagram identifies the effectiveness of an inspection policy based on minimal maintenance, major maintenance, and major repair parameters     

Mean time to first failure of repairable systems with one coldspare

A general (nonMarkov) 1-out-of-2:G system with statistically-identical components, repair, and cold standby is reviewed. Coverage is considered, viz, failures of the switching mechanism for activating the spare. The explicit derivation of the mean time-to-first-failure and its in-depth discussion appear to be new. The state transition graph and the Petri net both show the way to general (n-1)-out-of-n:G systems of this category. However, for n>2, results are given only for statistically-identical components which are all as good as new, when a repaired component is put to use. This limits applicability of results to electronic systems     

Analysis of system reliability with dependent repair modes

This paper proposes an imperfect-repair model for repairable systems where two repair modes, perfect and minimal, occur in accordance with a Markov chain. It investigates the characteristics of the model and presents a statistical procedure for estimating the lifetime distribution of the system, based on consecutive inter-failure times. Under the Brown-Proschan imperfect repair model, the system is repaired to: good-as-new under perfect-repair, its “condition just prior to failure” under minimal-repair. This imperfect-repair model generalizes the Brown-Proschan imperfect-repair model, by allowing first-order dependency between two consecutive repair modes. The model assumes that, at failure, the system undergoes either perfect repair (restore to like new) or minimal repair (restore to like “just before failure”), and the repair modes are subject to a Markov process. The estimation procedure is developed in a parametric framework for incomplete data where some repair modes are not recorded. The s-expectation-maximization principle is used to address the incomplete-data problem. Under the assumptions that the lifetime distribution belongs to a parametric family having aging property and explicit form of the survival function, an algorithm is developed for finding the MLE (maximum likelihood estimates) of the reliability parameters; the transition probabilities of the repair modes, as well as the distribution parameters. A Monte Carlo study shows the consistency, effect of aging rate, effect of transition types, and effect of missing data, for the estimates     

DSM perspective: another point of view

Distributed shared memory computers (DSMs) have arrived (G. Bell, 1992; 1996) to challenge mainframes. DSMs scale to 128 processors with two to eight processor nodes. As shared memory multiprocessors (SMPs), DSMs provide a single system image and maintain a “shared everything” model. Large scale UNIX servers using the SMP architecture challenge mainframes in legacy use and applications. These have up to 64 processors and a more uniform memory access. In contrast, clusters both complement and compete with SMPs and DSMs, using a “shared nothing” model. Clusters built from commodity computers, switches, and operating system scale to almost arbitrary sizes at lower cost while trading off SMPs single system image. Clusters are required for high availability applications. Highest performance scientific computers use the cluster (or MPP) approach. High growth markets, e.g., Internet servers, online transmission processing (OLTP), and database systems can all use clusters. The mainframe future of DSM may be questionable because: small SMPs are not as cost effective unless built from commodity components; large SMPs can be built without the DSM approach; and clusters are a cost effective alternative for most applications to SMPs, including DSMs for a wide scaling range. Nevertheless, commercial DSMs are being introduced that compete with SMPs over a broad range     

Design and analysis of general rotor-flux-oriented vector controlsystems

Reduced-order observers for rotor flux estimation of induction motors are considered. The “current” model and “voltage” model are obtained as special cases. It is shown that the flux dynamics form a nonlinear closed-loop system when the flux estimate is used for field orientation. The observer gain selection is extremely critical for good behavior of this system. A framework is developed, in which the properties of any gain selection can easily be assessed. Four candidate gain selections are considered, two of which yield schemes that do not use the rotor speed in their equations (inherently sensorless schemes). It is also shown that for any gain selection, an equivalent synchronous-frame implementation (i.e., indirect field orientation) always exists     

The evolution of transport network survivability

The bandwidth explosion ushered in by the popularity of the Internet has spurred the acceleration in the development and deployment of equipment supporting packet-based services. This-coupled with the widespread deployment of dense wavelength-division multiplexed systems in the core transport network to satisfy the corresponding increase in capacity demand-has led network planners to reconsider traditional approaches to network survivability. Existing architectures for transport network survivability were developed based on a ubiquitous circuit-switched/TDM network paradigm. As tariffed services increasingly migrate from circuit-switched/TDM to packet-switched/DWDM networks, survivability architectures must also evolve to meet the service requirements of this “new” packet-switched/DWDM network paradigm. We begin with an overview of existing strategies for providing transport network survivability, followed by an analysis of how the architectures for network survivability may evolve to satisfy the requirements of emerging networks     

Automated evaluation of critical features in VLSI layouts based onphotolithographic simulations

In this paper, we address the problem of identifying and evaluating “critical features” in an integrated circuit (IC) layout. The “critical features” (e.g., nested elbows and open ends) are areas in the layout that are more prone to defects during photolithography. As feature sizes become smaller (sub-micron range) and as the chip area becomes larger, new process techniques (such as, using phase shifted masks for photolithography), are being used. Under these conditions, the only means to design compact circuits with good yield capabilities is to bring the design and process phases of IC manufacturing closer. This can be accomplished by integrating photolithography simulators with layout editors. However, evaluation of a large layout using a photolithography simulator is time consuming and often unnecessary. A much faster and efficient method would be to have a means of automatically identifying “critical features” in a layout and then evaluate the “critical features” using a photolithography simulator. Our technique has potential for use either to evaluate the limits of any new and nonconventional process technique in an early process definition phase or in a mask house, as a postprocessor to improve the printing capability of a given mask. This paper presents a CAD tool (an Integrated CAD Framework) which is built upon the layout editor, Magic, and the process simulator, Depict 3.0, that automatically identifies and evaluates “critical features”     

The effect of emitter shortings on turn-off limitations and devicefailure in GTO thyristors under snubberless operation

The influence of the anode shorting on the turn-off failure of GTO thyristors is investigated. Two types of shorting patterns, viz., “finger”and “ring”-type anode designs, are compared with a non-shorted design. The inductively loaded GTO unit cells are measured under snubberless operation close to the safe-operating area (SOA) limit. The critical anode blocking voltage was obtained for a constant anode current density by varying the turn-off gain, G. The investigation has shown that the turn-off voltage capability of both types of anode-shorted GTO's is deteriorated for high G values. The “ring”-type anode design, however, shows better voltage blocking capability than the “finger” type. This behavior is attributed to the formation of a cylindrical high drift-current density filament at the end of the storage and beginning of the fall-time periods. The electric field in this region, which is referred to as a quasi space-charge region (QSC), is strongly G dependent. Measurements based on the time-resolved free-carrier absorption (FCA) technique are used to map the carrier-density redistribution inside the unit cell during the turn-off switching cycle. For the first time, 3-D simulations of the GTO cell are also presented in order to support the model of dynamic punch-through failure at high G values, which was proposed in earlier papers     

Reliability analysis of a two-unit parallel system with “preemptive priority” rule

This paper deals with a two-dissimilar-unit parallel redundant system in which unit 1 has preemptive priority in being repaired. Under the assumptions that the life time of unit 1 is an mth Erlang distribution, the life time of unit 2 and the repaired time of unit i(i = 1,2) are all general continuous distributions, we obtain almost all of the interesting reliability indices of the system. Finally, we give the upper and lower limits of a special case which has not been discussed elsewhere.     

平台化服务网络——新型移动通信系统架构研究

5G的部署让网络从服务个人向服务产业扩展。分析了移动通信系统的演进历程，提出了新的架构发展方向——平台化服务网络。面向网络碎片化这一产业互联网发展中的根本性挑战，新的架构中通过平台化解决成本问题，通过“服务化”实现异构能力，通过二者的协同实现网络可靠、可保障。给出了平台化服务网络的定义、总体架构及数学模型。结合5G服务化架构（service-based architecture,SBA）设计的创新实践，提出了服务设计的原则，并进而给出了层次化的设计思路。