Survey of reliability and availability prediction methods from the viewpoint of software architecture

Many future software systems will be distributed across a network, extensively providing different kinds of services for their users. These systems must be highly reliable and provide services when required. Reliability and availability must be engineered into software from the onset of its development, and potential problems must be detected in the early stages, when it is easier and less expensive to implement modifications. The software architecture design phase is the first stage of software development in which it is possible to evaluate how well the quality requirements are being met. For this reason, a method is needed for analyzing software architecture with respect to reliability and availability. In this paper, we define a framework for comparing reliability and availability analysis methods from the viewpoint of software architecture. Our contribution is the comparison of the existing analysis methods and techniques that can be used for reliability and availability prediction at the architectural level. The objective is to discover which methods are suitable for the reliability and availability prediction of today’s complex systems, what are the shortcomings of the methods, and which research activities need to be conducted in order to overcome these identified shortcomings. The comparison reveals that none of the existing methods entirely fulfill the requirements that are defined in the framework. The comparison framework also defines the characteristics required of new reliability and availability analysis methods. Additionally, the framework is a valuable tool for selecting the best suitable method for architecture analysis. Furthermore, the framework can be extended and used for other evaluation methods as well.     

On-line control flow error detection using relationship signatures among basic blocks

Computer systems operating in space environment are subject to different radiation phenomena, whose effects may lead to a control flow fault occurring in software system, which can cause unpredictable behaviors of computer-based systems. According to the specialty of space environment, We propose a technique called RSCFC (Relationship Signatures for Control Flow Checking) which is based on the partition of programs into basic blocks. Firstly, it exploits the relationship among the blocks, then assigns a signature, into which the relationship is coded, to each basic block. Control flow faults are detected through taking AND operation between the run-time signature and the location info of the current block with extra instructions induced at the beginning and the end of each block. A fault injection experiment was performed with several C benchmark programs. The result suggests that about 33% (20.7-68.8%) of the injected branching faults produced undetected incorrect outputs without RSCFC; however, with RSCFC, the above number declines to 11% (2.8-20.4%). Compared with previous techniques, RSCFC has the characteristics of both high fault coverage and low memory and performance overhead.     

QQF函数数值计算及图示软件

QQF 软件可以建立不限容量的函数(公式)库,计算和图示库中任一函数在指定范围的数值,并在二维或三维空间显示该函数的图象。软件中使用了特殊的编译技巧,用户能直接以人机对话方式建立和维护自己的函数库,方便地调用其中任何函数。QQF.EXE 可在 IBM—PC及其兼容机上运行。     

A re-entrant line model for software product testing

In today’s competitive environment for software products, quality is an important characteristic. The development of large-scale software products is a complex and expensive process. Testing plays a very important role in ensuring product quality. Improving the software development process leads to improved product quality. We propose a queueing model based on re-entrant lines to depict the process of software modules undergoing testing/debugging, inspections and code reviews, verification and validation, and quality assurance tests before being accepted for use. Using the re-entrant line model for software testing, bounds on test times are obtained by considering the state transitions for a general class of modules and solving a linear programming model. Scheduling of software modules for tests at each process step yields the constraints for the linear program. The methodology presented is applied to the development of a software system and bounds on test times are obtained. These bounds are used to allocate time for the testing phase of the project and to estimate the release times of software.     

图像增强技术在X射线探伤中的应用

数字图像处理技术可提高缺陷的检测与分类能力,在无损检测中的作用越来越重要。介绍利用Photoshop软件进行射线检测图像增强的技术。图像处理结果表明,该技术可使图像清晰度和分辨率大大提高,资料便于保存,并且可大大降低工作强度。     

智能测控仪表的研究

本文重点介绍以ＭＩＩＣＲＯＣＨＩＰ公司的ＰＩＣ１６Ｃ１７单片机为核心的智能测控仪表的研究。其中包括硬件的软件的结构设计．     

漫湾水轮发电机转子磁极键装配出现的问题

本文针对漫湾水电站机组安装中，由于国家规范和厂家规程要求不明确，出现的对转子磁极键装配的不同认识和不合理施工方法，通过对机组各种状态下受力状况进行计算、分析，论述水轮发电机转子磁极键的装配要求及改进意见。     

Using databases in history teaching

Abstract In recent years, considerable interest has been shown in the classroom use of historical databases. Several database programs for microcomputers have become available, and as far as history teaching is concerned, they appear to have been mainly used for the analysis of mid-nineteenth century census schedules. At the same time, it is not clear that the curricular issues concerning the use of these programs has been fully explored. The purpose of this article is to raise these issues and to relate them to the use of several database programs currently used in classroom history teaching.     

基于UMAC的开放式数控平台的构建与应用

基于UMAC控制器开发了一种开放式数控平台,硬件平台由"IPC+UMAC"组成,IPC和UMAC之间通过以太网进行通讯;软件平台基于Windows操作系统,由Windows上位应用软件和运行于UMAC中的PLC和G代码程序组成.通过该平台在五轴雕铣机数控加工中的应用表明,该开放式数控系统具有速度快、精度高、稳定性好等优点,适合用于多电动机、高精度的运动控制.     

能量色散X荧光分析系统软件设计

本文介绍的是新研制的能量色散X荧光分析软件。本软件采用树状结构,具有操作方便、运行速度快、功能丰富、容错能力强等特点。本软件实现了X荧光分析的数据采集、谱的解析和基体校正等功能,其效果达到了国际上同类产品的水平。