基于形式规范的协议一致性测试的可靠性分析

可以用于形式规范的描述语言很多,但存在一种统一的方法对形式规范进行一致性测试。该文采用统计的方法分析基于形式规范的协议一致性测试的可靠性,通过计算给出待测实体经过这种测试后所能达到的可靠性的置信区间,特别指出在零错误下影响可靠性的条件。     

软件无线电标准符合性测试系统设计

随着软件无线电技术的迅速发展,越来越多厂家开展了基于软件无线电标准的技术研究和产品研制.由于各厂家对标准的理解不一致,研制软件产品的实现存在差异,导致未经符合性测试的软件之间不能相互兼容,需花费大量时间来进行波形移植开发和系统集成.针对该问题,提出了一种软件无线电系统标准符合性测试系统的实现方式,给出了系统测试内容、测...     

宽带放大器可靠性问题浅析

叙述了国产高频宽带放大器的质量和可靠性现状，详细介绍了这类产品的质量一致性检验、可靠性摸底试验和现场使用过程中出现的可靠性问题，用统计的方法得出了可靠性特征量，通过对失效样品的失效分析，总结出宽带放大器主要的失效模式和失效机理，并提出了消除和减少失效、提高宽带放大器可靠性的措施和建议。     

Failure Rate Calculations Using a Programmable Calculator

This paper describes a TI 59 program which calculates the acceleration factor between any two temperatures, equivalent unit-hours at one temperature based on actual test hours at a second temperature, the x2 approximation at any of seven s-confidence levels, and the s-confidence limit failure rate estimate in both %/1000 hours and FITs. The program allows numerous entries of separate sample results which the calculator stores and then performs a single failure rate estimate calculation. Required inputs are test temperature, temperature at which the failure rate estimate is desired, the activation energy, and the number of failures during the test. The equations for the program are reviewed and tables are included showing all labels and memories used, and the 355 program steps listing.     

A Statistical Model for Combining Biased Expert Opinions

A statistical model is developed to combine subjective estimates of an unknown parameter. The maximum likelihood estimator is a weighted geometric mean of adjusted estimates, each being adjusted to remove certain s-biases. The mean-square error of this estimator is compared to that of an unweighted geometric mean of unadjusted estimates; under the assumed model, this unweighted estimator is inferior except when there is no s-bias and when all estimates have the same uncertainty. An s-unbiased version of the maximum likelihood estimator has even smaller mean-square error in an example problem. A simple s-confidence interval estimator is derived.     

Sequential Testing of Components for System Reliability

It is often desirable to construct s-confidence limits for system reliability on the basis of data obtained from `pass-fail' tests on the components of the system. This paper presents a general method for sequentially testing the components that provides data from which these s-confidence limits can be easily derived. The method is applicable to any s-coherent system for which the reliability function is known. It is a generalization of a scheme given by Winterbottom and Verrall for systems composed of units arranged either in series or parallel.     

Evaluation of the ACR-NEMA standard for communications in digital radiology

An implementation and evaluation of a prototype multivendor communications system which complies with the American College of Radiology (ACR) and the National Electrical Manufacturers Association (NEMA) standard for communications in digital radiology is discussed. The system allows communications between interfaces from different manufacturers within a networked environment. The implementation includes network software compatible with the International Standards Organization's Open Systems Interconnect standard. The experience of the implementation effort and the evaluation of the system provide the basis for a critique of the ACR-NEMA standard. It is concluded that the ACR-NEMA standard is not well suited for application to the networked environment of picture archiving and communications systems. Two possible solutions are recommended for this problem. The first is a major revision of the existing standard. The second is the development of a family of network communications standards for digital radiology.     

TD—SCDMA／GSM双模终端RRM一致性测试的实现

终端无线资源管理（RRM）一致性测试是终端入网认证测试的重要组成部分。在3G网络正式运营之后,TD-SCDMA／GSM双模终端RRM一致性测试对终端的研发和认证具有重要意义。文中介绍了基于TTCN的一致性测试原理和测试方法,双模终端RRM一致性测试的具体内容以及组成测试系统的硬件、软件结构。同时结合系统间非同步切换测试例详细介绍了TD／GSM双模终端RRM一致性测试的具体实现并给出了测试的结果。     

MPEG-2视频解码器一致性测试

结合ISO／IEC13818-4标准，给出了测试并验证MPEG-2视频解码器一致性的方法，并利用此方法对所设计的MPEG一2视频解码芯片进行一致性测试，结果表明该芯片已基本符合MPEG-2标准的要求。     

藏文软件标准符合性检测的研究与设计

软件产品的标准符合性检测是衡量产品质量与性能的重要方法.从藏文信息处理标准角度出发,分析与总结了藏文标准符合性检测的含义与检测内容.针对Windows操作系统产品的通用模块,分别设计了实施藏文编码字符集标准、字型标准与键盘布局标准符合性检测的具体内容、检测流程与检测算法.     

Approximate Confidence Intervals for Reliability of a Series System

Two solutions are proposed for estimating s-confidence intervals for reliability of a repairable series system comprised of non-constant failure rate components: 1) the system is treated as a sum of renewal processes with the mean and variance of total number of system failures being computed from the moments of failure times of the components; and 2) a pseudo-Bayesian solution is derived for the mean and variance of the log-reliability of a system of Weibull components. In both solution approaches, the central limit theorem is invoked for a sum of component random variables determined from test data such as number of failures or log-reliabilities. s-Confidence limits are then approximated using Gaussian probability tables. The intervals derived yield close-to-exact frequency limits, depending on such variables as number of test failures, number of components, and component parameters.     

A generalized geometric de-eutrophication software-reliabilitymodel

The authors present a new software reliability model, called the lognormal proportional model (LPM). It belongs to the class of proportional models and can be viewed as a Bayes generalization of Moranda's geometric de-eutrophication model or deterministic proportional model (DPM). It is based on the idea that the modeling of software improvement should be stochastic rather than deterministic. The LPM appears to be a variance components linear model that leads to the computation of several estimators of the parameters. The authors present a statistical test to compare the goodness-of-fit of the general LPM and the DPM, for a given realization of the failure process. An application to actual software failure data is briefly described. The LPM fits most data sets better than the DPM. This emphasizes the great variability of most software reliability data     

EPA协议中事件服务的实现和测试

EPA是我国第一个拥有自主知识产权并被国际电工委员会（IEC）认可的工业自动化领域国际标准。本文在严格按照EPA标准完全实现EPA事件服务组以及深入理解EPA协议一致性测试原理的基础上,着重研究了EPA协议中关于报警的事件服务的测试方法,提出了一种测试EPA事件服务的一致性测方法。测量中主机作为控制台,控制测试流程、设置测试参数,以及显示结果,测试代理借助协议栈的通信能力与主机测试软件进行测试命令的交互。     

A nonparametric nonstationary procedure for failure prediction

The time between failures is a very useful measurement to analyze reliability models for time-dependent systems. In many cases, the failure-generation process is assumed to be stationary, even though the process changes its statistics as time elapses. This paper presents a new estimation procedure for the probabilities of failures; it is based on estimating time-between-failures. The main characteristics of this procedure are that no probability distribution function is assumed for the failure process, and that the failure process is not assumed to be stationary. The model classifies the failures in Q different types, and estimates the probability of each type of failure s-independently from the others. This method does not use histogram techniques to estimate the probabilities of occurrence of each failure-type; rather it estimates the probabilities directly from the values of the time-instants at which the failures occur. The method assumes quasistationarity only in the interval of time between the last 2 occurrences of the same failure-type. An inherent characteristic of this method is that it assigns different sizes for the time-windows used to estimate the probabilities of each failure-type. For the failure-types with low probability, the estimator uses wide windows, while for those with high probability the estimator uses narrow windows. As an example, the model is applied to software reliability data.     

Determination of Reliability Using Event-Based Monte Carlo Simulation Part II

Analytic determination of reliability of general systems becomes increasingly difficult as the system complexity increases. Inclusion of s-dependent components and/or allowing repair of failed components makes such analysis virtually impossible. This paper extends the Monte Carlo simulation procedure of Kamat and Riley to estimate the reliability of such systems. A computer program finds all minimal tie-sets from a coded reliability flow graph and performs the simulation. In each replication, the s-dependency of failures and/or repair of failed components is incorporated in the generation of pseudorandom time-to-failure through modification of the failure rate for each affected component. A search through the minimal tie-sets identifies the success or failure of the system at each value of required time of operation. The computer program estimates the system reliability as a function of time with approximate individual (for each time point) 95 percent symmetric s-confidence limits.     

链路管理协议的一致性测试

链路管理协议(LMP)是自动交换光网(ASON)控制平面协议栈的一个重要组成部分,由于厂家对协议实现的不同理解,通信设备的协议非一致性问题日趋严重。本文对LMP协议进行了分析,介绍了一种基于测试仪的LMP一致性测试方案,对运行控制平面协议栈的仿真机进行了测试,给出了测试结果分析,并总结了ASON测试现状。     

产品设计与器材保障平台软件设计与实现

从器材选择、采购、试验到贮存传递、现场使用、失效分析、质量反馈等质量保证的全过程,介绍了产品设计与器材保障平台软件系统的功能分析。设计思想、实现方法和特点。该软件系统是型号总体和分系统承制单位开展电子产品质量保证活动和信息化建设重要的支撑应用平台。     

Estimation of Weibull Parameters With Competing-Mode Censoring

Existing results are reviewed for the maximum likelihood (ML) estimation of the parameters of a 2-parameter Weibull life distribution for the case where the data are censored by failures due to an arbitrary number of independent 2-parameter Weibull failure modes. For the case where all distributions have a common but unknown shape parameter the joint ML estimators are derived for i) a general percentile of the j-th distribution, ii) the common shape parameter, and iii) the proportion of failures due to failure mode j. Exact interval estimates of the common shape parameter are constructable in terms of the ML estimates obtained by using i) the data without regard to failure mode, and ii) existing tables of the percentage points of a certain pivotal function. Exact interval estimates for a general percentile of failure-mode-j distribution are calculable when the failure proportion due to failure-mode-j is known; otherwise a joint s-confidence region for the percentile and failure proportion is calculable. It is shown that sudden death endurance test results can be analyzed as a special case of competing-mode censoring. Tabular values for the construction of interval estimates for the 10-th percentile of the failure-mode-j distribution are given for 17 combinations of sample size (from 5 to 30) and number of failures.     

基于SMIv2的ICS文稿及生成方法

借鉴ITU-T的实现一致性声明(ICS,Implementation conformance statement)文稿设计方法,分析了SMIv2的文法规则,提出了基于SMIv2的ICS文稿格式.该ICS文稿可以反映出管理信息模型中描述的各种管理对象信息,为网管接口的实现者声明其对管理信息模型的实现情况提供标准化的描述形式,能够满足基于SNMP的网管接口信息模型一致性测试需求.还给出了一种根据MIB文件自动生成基于SMIv2的ICS文稿的方法.     

Survey of reliability and availability evaluation of complex networks using Monte Carlo techniques

Generally there are four main difficulties in evaluating complex large-scale system reliability, availability and MTBF: the system structure may be very complex; subsystems may follow various failure distributions; subsystems may conform to arbitrary failure and repair distributions for maintained systems; the failure data of subsystems are sometimes not sufficient, reliability test sample sizes tend to be small. It is difficult and often impossible to obtain s-confidence limits of them by classical statistics. Monte Carlo technique combined with Bayes method is a powerful tool to solve this kind of problems. In this survey, the typical existing Monte Carlo reliability, availability and MTBF simulation procedures, variance reduction methods, and random variate generation algorithms are analyzed and summarized. The advantages, drawbacks, accuracy and computer time of Monte Carlo simulation in evaluating reliability, availability and MTBF of a complex network are discussed. Finally, some conclusions are drawn and a general Monte Carlo reliability and MTTF assessment procedure is recommended.