网络系统可靠性仿真

随着网络内节点和链路数量的增加，对于不能分割的复杂网络系统的可靠性分析受到限制，采用可靠性仿真是可用的技术途径之一。     

以信息化网络管理系统提升网络可靠性

本文主要分析了平阳广电利用生产商开发的基于SNMP协议的HFC网络管理系统来对网络设备进行监控和管理,对网络设备故障的及时预警、查找、处理起到重要作用,转被动抢修为主动防御。保证了系统的稳定运行,为安全播出提供了强有力的保障。     

集成电路网络系统的可靠性分析

建立了集成电路网络系统的可靠性数学模型。并在此基础上进行了一些可靠性分析与预测。     

System Stress-Strength Reliability: The Multivariate Case

Present day complex systems with dependence between their components require more advanced models to evaluate their reliability. We compute the reliability of a system consisting of two subsystems S ₁, and S₂ connected in series, where the reliability of each subsystem is of general stress-strength type, defined by R₁ = P(A ^TX > B^TY). A & B are column-constant vectors, and strength X & stress Y are multigamma random vectors, i.e. (X, Y) ~ MG (alpha, beta), where alpha and beta are k-dimensional constant vectors. A Bayesian approach is adopted for R₂ = P(B ^TW > 0), where W is multinormal, i.e. W ~ MN(mu, T), with the mean vector mu, and the precision matrix T having a joint s-normal-Wishart prior distribution. Final computations are carried out by simulation, an approach which plays a major role in this article. The results obtained show that the approach adopted can deal effectively with the dependence between components of X & Y     

网络系统可靠度的BDD算法

文中研究3-状态设备网络系统2-终端可靠度的计算问题。BDD是布尔函数的图形表示形式。武小悦和沙基昌提出了一个采用BDD方法求2-状态网络系统的不交化最小路集,从而直接计算网络系统可靠度的算法。通过引入简化技术,结合归约公式和BDD技术,给出了一个计算3-状态设备网络2-终端可靠度的一个新算法;算法有效地消除了冗余项,并且产生的分枝树具有结点少,可有效得到可靠度符号表达式。     

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。     

Reliability Evaluation of a Flow Network

This paper presents a method for evaluating reliability of a flow network using the concept of lexicographic ordering. Associated with each branch of the network are the flow capacity and the probability that the branch functions properly. The network is successful if a specified units of flow can be transmitted through the network. A labeling scheme is used to route the flow through the network and a computer program for implementing the algorithm is given in the Supplement.     

SPN在网络安全保密系统可靠性分析中的应用

文章针对网络安全保密系统的安全需求和运行特性,引入Petri网理论指导网络安全保密系统的可靠性建模与分析过程。首先详细描述了运用随机Petri网对网络安全保密系统进行可靠性建模与分析的具体方法和过程;然后给出一个实例,对系统的保密性服务子系统进行建模,并分析了该子系统在安全运行状态下的可靠性。通过对可靠性建模分析方法的应用,不仅实现了系统方案设计阶段可靠性的可评估性,而且提高了系统后期开发过程的可操作性。     

Significance of Equipment Reliability in a Telephone Network

A reliability concept is considered in which telephone traffic is taken into account for a telephone network. An analytic model of a simple network with parallel paths shows how telephone traffic is included in the telephone network reliability analysis. Examples are given to demonstrate the usefulness of this concept in the investigation of an optimum inspection policy for each path, and the effects of path age and failure rate on telephone network service.     

舰载网络系统可靠性参数体系研究

舰载网络系统可靠性对舰船作战效能发挥的影响越来越大,但目前针对舰载网络系统可靠性技术的研究很少.该文对舰载网络系统可靠性参数体系建立的原则、要求及程序进行了分析,并结合系统特点,给出了舰载网络系统可靠性测度及参数体系,旨在为舰载网络系统可靠性技术研究奠定基础.     

约束条件下随机流网络可靠度的计算

在质量管理的角度上,系统可靠度的计算是随机流网络的一个很重要的方面。一般计算网络可靠度的方法是在考虑边有可能无效,节点保持完好且没有流量的限制的情况下进行的。文中提出一种在既考虑节点流量的限制又考虑整个网络成本预算的约束条件下计算网络可靠度的方法,使其更接近实际。     

Product Multicommodity Flow in Wireless Networks

We provide a tight approximate characterization of the n-dimensional product multicommodity flow (PMF) region for a wireless network of n nodes. Separate characterizations in terms of the spectral properties of appropriate network graphs are obtained in both an information-theoretic sense and for a combinatorial interference model (e.g., protocol model). These provide an inner approximation to the n ²-dimensional capacity region. Our results hold for general node distributions, traffic models, and channel fading models. We first establish that the random source-destination model assumed in many previous results on capacity scaling laws, is essentially a one-dimensional approximation to the capacity region and a special case of PMF. We then build on the results for a wireline network (graph) that relate PMF to its spectral (or cut) properties. Specifically, for a combinatorial interference model given by a network graph and a conflict graph, we relate the PMF to the spectral properties of the underlying graphs resulting in simple computational upper and lower bounds. These results show that the 1/radicn scaling law obtained by Gupta and Kumar for a geometric random network can be explained in terms of the scaling law of the conductance of a geometric random graph. For the more interesting random fading model with additive white Gaussian noise (AWGN), we show that the scaling laws for PMF can again be tightly characterized by the spectral properties of appropriately defined graphs-such a characterization for general wireless networks has not been available before. As an implication, we obtain computationally efficient upper and lower bounds on the PMF for any wireless network with a guaranteed approximation factor.     

Reliability Evaluation of a Network with Delay

In a computer or communication network, the reliability and transfer-delay of communication are important measures of performance. This paper describes a method of evaluating the reliability of a network with delay. When network elements fail, delay is defined as the length of the shortest remaining path between two specified nodes. We find the occurrence probability of events that a central node can communicate with a group of terminal nodes so that a specified delay is not exceeded. The desired events are mutually exclusive and contain a tree. Our algorithm efficiently generates all the events by noting network topology. The paper includes the case of several central nodes.     

Using the Decomposition-Tree of a Network in Reliability Computation

Available algorithms for measures of network reliability require computation time f(n) where f is at least exponential in n, the number of failure-prone elements in the system. Modularization is a familiar method of decomposing a network reliability problem into a set of subproblems. This decomposition reduces required computation time from f(n) to a sum of f(ni), ni < n, usually a considerable saving. For a 2-terminal communication network, the decomposition tree of a network provides the identity of the modules and an easily read map of the relations among them. The decomposition tree is derived by finding the triconnected components of the underlying graph. Reducing computation time by finding and analyzing the triconnected components of a network has been proposed for the reliability problems of 2-terminal communication, all-terminal communication, and feasible transportation flow. This paper introduces the use of the decomposition tree for reliability computation purposes, presents a general algorithm based on the tree, and demonstrates its application to the problems named above, as well as to the problem of feasible shortest path.     

通信网网络管理系统的可靠性与安全性研究

首先给出了通信网网络管理系统可靠性的定义和指标,然后主要从通信网网络管理系统的结构模式、硬件可靠性设计和软件可靠性设计三个角度出发,详细阐述了提高通信网网络管理系统可靠性的措施,最后从安全性特征、安全层次、安全威胁和安全防范措施四个方面论述了通信网网络管理系统的安全性问题。     

虹信直放站监控系统提升网络安全可靠行性

直放站作为一种普遍应用的通信设备,其稳定性、可靠性已成为其能否持续稳步发展的关键,如果设备出现故障或者参数调整不当可能会对整个通信网络产生严重影响,因此,为保证直放站系统的可靠性和可维护性,直放站设备在实现其信号覆盖效果的同时,能否有效地实现其运行状态的日常监控,在第一时间发现设备故障,有效降低客户投诉率,已成为直放站设备非常重要的考核指标,这样就必然对直放站监控系统提出较高的要求.     

A Recursive Method Based on Case Analysis for Computing Network Terminal Reliability

In this paper a unified treatment is provided of the methods for computing terminal reliability based on recursive case analysis. The possible choices in case enumeration are discussed, and a rationale is given to support a particular policy. Simplification and decomposition techniques are also examined, and some experimental results are described, obtained with a computer program, which is a good compromise between efficiency and simplicity.     

相关竞争失效场合雷达功率放大系统可靠性评估

针对相关竞争失效场合难以获取高可靠部件的性能分布信息,无法对系统可靠性进行准确估计的问题.提出了相关竞争失效场合下考虑认知不确定性的多态系统可靠性评估方法.该方法首先通过假定部件突发失效阈值为递减型随机过程来表征累积退化与突发失效的相关性,同时为降低对部件认知不确定性的影响,假定冲击引起的部件性能损伤分布参数和突发失效参数均为区间变量,建立基于区间变量的部件性能分布模型;而后对传统的通用生成函数方法进行改进,给出了区间通用生成函数的定义及其运算法则;最后对某型雷达功率放大系统的可靠性进行分析.该方法不仅克服了部件的失效模式复杂、状态信息少的不足,且方法简单、思路清晰,具有很强的通用性和工程应用价值.     

网络可靠性仿真

讨论了在链路以及节点均可能失效情况下,把节点的失效等效为与之相连链路的失效,运用蒙特卡洛法对网络可靠性进行仿真。并给出了仿真次数对仿真结果的误差的影响。     

Optimal Reliability of a Complex System

In a complex system where the redundant units cannot be reduced to a purely parallel or series configuration, the reliability is obtained by using Bayes' theorem. A mathematical model is formulated for the reliability of a system with nonlinear constraints. The system reliability is optimized based on the model and the solution is obtained by using the sequential unconstrained minimization technique (SUMT). This method is an efficient method for solving this type of problem. Two life support systems, one is the communication system of a two-man space capsule and another is a high-pressure oxygen supply system in a space capsule, have been identified to have the complex system configuration treated in this work.