兼顾可用性和可靠性的可视密码最佳方案

自1994年Naor和Shamir提出可视密码被提出以来,可视密码的像素扩展和图像对比度差一直是需要解决的问题。在m点加密的基础上,在兼顾可用性和可靠性的前提下,提出了实现可视密码的最佳方案,一方面能够使分存图像像素不产生扩展,即分存图像与加密图像一样大;另一方面,通过重构使恢复后的图像达到最好的对比度。     

Fuzzy Bayesian reliability and availability analysis of production systems

To have effective production planning and control, it is necessary to calculate the reliability and availability of a production system as a whole. Considering only machine reliability in the calculations would most likely result unmet due dates. In this study, a new modelling approach for determining the reliability and availability of a production system is proposed by considering all the components of the system and their hierarchy in the system structure. Components of a production system are defined as production processes; components of the processes are defined as sub-processes. In this hierarchical structure we could model all kinds of failures such as material and supply, management and personnel, and machine and equipment. In the analysis, a fuzzy Bayesian method is used to quantify the uncertainties in the production environment. The suggested modelling approach is illustrated on an example. In the example, also a separate reliability and availability analysis is conducted which only considered machine failures, and the results of both analyses are compared.     

基于单星可靠度的星座可用性建模仿真

星座是由多颗卫星组成的复杂大系统,各组成单元相互影响、相互制约,共同决定了星座系统的成本和性能。而当前航空航天领域的设计原则已从性能绝对主导的模式逐步转向追求性能、运行费用、可靠性、可维护性等多方面综合平衡。在当前情况下,如何在满足性能要求的前提下最小化系统成本已经成为亟待解决的问题。针对地面备份卫星的补网模式,在分析星座可用性的基础上,通过对单星可靠度和补网卫星发射周期对星座系统可用性的关系进行建模,最后仿真分析得出单星可靠度的变化对星座可用性的影响。     

Hierarchical modeling of availability in distributed systems

Distributed computing systems are attractive due to the potential improvement in availability, fault-tolerance, performance, and resource sharing. Modeling and evaluation of such computing systems is an important step in the design process of distributed systems. We present a two-level hierarchical model to analyze the availability of distributed systems. At the higher level (user level), the availability of the tasks (processes) is analyzed using a graph-based approach. At the lower level (component level), detailed Markov models are developed to analyze the component availabilities. These models take into account the hardware/software failures, congestion and collisions in communication links, allocation of resources, and the redundancy level. A systematic approach is developed to apply the two-level hierarchical model to evaluate the availability of the processes and the services provided by a distributed computing environment. This approach is then applied to analyze some of the distributed processes of a real distributed system, Unified Workstation Environment (UWE), that is currently being implemented at AT&T Bell Laboratories     

Coverage Modeling and Reliability Analysis Using Multi-state Function

Fault tree analysis is an effective method for predicting the reliability of a system.It gives a pictorial representation and logical framework for analyzing the reliability.Also,it has been used for a long time as an effective method for the quantitative and qualitative analysis of the failure modes of critical systems.In this paper,we propose a new general coverage model (GCM) based on hardware independent faults.Using this model,an effective software tool can be constructed to detect,locate and recover fault from the faulty system.This model can be applied to identify the key component that can cause the failure of the system using failure mode effect analysis (FMEA).     

Test-execution-based reliability measurement and modeling for largecommercial software

The paper studies practical reliability measurement and modeling for large commercial software systems based on test execution data collected during system testing. The application environment and the goals of reliability assessment were analyzed to identify appropriate measurement data. Various reliability growth models were used on failure data normalized by test case executions to track testing progress and provide reliability assessment. Practical problems in data collection, reliability measurement and modeling, and modeling result analysis were also examined. The results demonstrated the feasibility of reliability measurement in a large commercial software development environment and provided a practical comparison of various reliability measurements and models under such an environment     

Measuring and modeling usage and reliability for statistical Webtesting

Statistical testing and reliability analysis can be used effectively to assure quality for Web applications. To support this strategy, we extract Web usage and failure information from existing Web logs. The usage information is used to build models for statistical Web testing. The related failure information is used to measure the reliability of Web applications and the potential effectiveness of statistical Web testing. We applied this approach to analyze some actual Web logs. The results demonstrated the viability and effectiveness of our approach     

基于Markov过程的IaaS系统可用性建模与分析方法

针对现有基础设施即服务（IaaS）可用性模型难以计算存在多个可用物理机器（PM）概率的问题,提出一种基于Markov过程的IaaS可用性分析方法。首先,将计算资源划分为hot PM、warm PM和cold PM三类;然后,结合资源分配过程的相应阶段对可用性影响进行建模,分别生成对应的三种分配子模型,子模型之间通过不同种类计算资源的转换关系相互协作,构建系统整体模型;其次,基于Markov过程建立方程组以对可用性模型进行求解;最后,结合实例对分析模型进行验证,并对PM变迁速率等关键影响因素进行了分析。实验结果表明,增加PM尤其是cold PM的数量有助于提升IaaS的可用性。所提方法可以用于评估IaaS存在一个或多个可用PM的概率。     

基于Markov过程的IaaS系统可用性建模与分析方法

针对现有基础设施即服务（IaaS）可用性模型难以计算存在多个可用物理机器（PM）概率的问题，提出一种基于Markov过程的IaaS可用性分析方法。首先，将计算资源划分为hot PM、warm PM和cold PM三类；然后，结合资源分配过程的相应阶段对可用性影响进行建模，分别生成对应的三种分配子模型，子模型之间通过不同种类计算资源的转换关系相互协作，构建系统整体模型；其次，基于Markov过程建立方程组以对可用性模型进行求解；最后，结合实例对分析模型进行验证，并对PM变迁速率等关键影响因素进行了分析。实验结果表明，增加PM尤其是cold PM的数量有助于提升IaaS的可用性。所提方法可以用于评估IaaS存在一个或多个可用PM的概率。     

Computer aided reliability modeling and applications in semiconductor manufacturing

We present a computerized reliability model based on evolving Markov processes. The model has the capability to self-organize and adopt. The differences between knowledge engineering methods and the proposed model are also discussed.     

考虑环境因素的分布式系统可靠性建模及其分析

为建立可变工作环境下分布式系统可靠性模型,提出受控混合随机Petri网,即用连续库所中的托肯控制离散变迁的变迁率．以此反映工作环境对部件可靠性的影响,从而推理出环境对系统可靠性的影响．在此模型的基础上,采用蒙特卡罗方法进行不同环境下系统可靠性仿真求解,解决了可变工作环境下分布式系统的可靠性建模及其分析问题．最后,以一个C^4ISR系统为例说明了该方法是一种考虑可变工作环境影响的分布式系统可靠性分析的可行方法．     

基于退化数据与marker数据综合的产品可靠性建模分析

基于性能退化数据的可靠性建模分析方法,为现代工业中长寿命、高可靠产品的可靠性研究提供了重要途径,但在破坏性测量中无法获得足够的产品性能退化数据.对此,综合利用产品性能退化数据和marker数据对产品可靠性进行建模,不仅能够提高可靠性评估的精度,还可以在产品运行过程中通过对marker的测量来预测产品剩余寿命,从而为产品维修、更换以及备件决策提供依据.采用二元Wiener过程对产品的性能参数和marker进行建模,给出模型参数的估计方法和基于marker测量数据的剩余寿命预测方法,并通过仿真示例验证所提出方法的有效性.     

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.     

基于GM模型的软件可靠性建模

将灰色理论应用于软件可靠性建模研究,通过对历史失效数据进行建模,对软件的下一步失效时刻进行预测。为验证该模型的预计精度,将其应用于多组广泛被认可的数据,通过计算度量元短期相对误差（SRE）与经典的可靠性模型进行比较,结果表明,基于GM的模型对将来失效时间间隔的预测更加准确。     

Fuzzy modeling of system behavior for risk and reliability analysis

The main objective of the article is to permit the reliability analyst's/engineers/managers/practitioners to analyze the failure behavior of a system in a more consistent and logical manner. To this effect, the authors propose a methodological and structured framework, which makes use of both qualitative and quantitative techniques for risk and reliability analysis of the system. The framework has been applied to model and analyze a complex industrial system from a paper mill. In the quantitative framework, after developing the Petrinet model of the system, the fuzzy synthesis of failure and repair data (using fuzzy arithmetic operations) has been done. Various system parameters of managerial importance such as repair time, failure rate, mean time between failures, availability, and expected number of failures are computed to quantify the behavior in terms of fuzzy, crisp and defuzzified values. Further, to improve upon the reliability and maintainability characteristics of the system, in depth qualitative analysis of systems is carried out using failure mode and effect analysis (FMEA) by listing out all possible failure modes, their causes and effect on system performance. To address the limitations of traditional FMEA method based on risky priority number score, a risk ranking approach based on fuzzy and Grey relational analysis is proposed to prioritize failure causes.     

Measuring, modeling, and augmenting reliability of man-machine systems

This paper discusses analytical and empirical trends in dealing with human reliability. It reflects on the nature of human error and man-machine reliability, and poses some serious problems of definition which affect numerical results. Techniques for enhancing man-machine system reliability are presented.     

导弹天线罩参数化有限元建模和热可靠性分析

基于Pro/ENGINEER,Patran和MSC Nastran,以坚晶石导弹天线罩为研究对象,结合参数化有限元建模方法,将天线罩结构尺寸、材料性能和热流输入等作为随机因素,使用蒙特卡罗数字模拟法对其进行热可靠性分析,详述参数化建模和可靠性分析的流程,得到天线罩热应力的概率分布、随机因素与热应力的变化关系以及天线罩热可靠度等可靠性分析数据.结果显示,本文的天线罩热可靠度为99.93%.本研究证实对导弹天线罩进行参数化有限元建模和可靠性分析的可行性.     

基于退化建模的可靠性分析研究现状

基于退化数据具有比失效时间数据更多的可靠性信息,为高可靠、长寿命产品提供了一种有效的可靠性分析方法,为此对退化建模领域的相关理论研究与工程实践作了阶段性的总结．首先介绍了退化建模的概念和发展现状;接着给出了退化模型与失效时间分布之间的关系;然后按无应力因子和有应力因子两种情形对退化建模的相关研究进行了概述;最后简要分析了退化建模领域中的热点问题,并对下一步的研究进行了展望．