普适计算系统可用性度量

普适计算系统可用性度量具有典型的面向用户特点,为刻画用户行为需要引入具有非指数分布性质的用户状态,并且需要考虑用户态与系统态关联分析时的复杂情况。传统的连续时间马尔科夫链和半马尔科夫过程都不能很好地对以上情况给予分析。鉴于此,文章基于马尔科夫重生过程(MRGP)提出了普适计算系统的可用性度量方法。首先建立具有普适计算模式的用户模型,基于此构建了普适计算系统可用性度量的MRGP模型,对可用性进行了随机过程分析,给出了对应瞬态和稳态行为的度量方法,结合普适计算模式的特点定义了普适计算系统请求可用性度量。最后进行了数值分析,评价了普适计算系统可用性在MTTF和MTTR下的变化情况,据此导出来构建高可用普适计算系统需要考虑一些原则,并分析了用户和系统参数等因素对普适计算系统可用性度量的影响。     

基于MRGP的普适计算可用性度量

普适计算模式追求随时随地的计算境界，对可用性管理提出了很高的要求。该文基于定量分析的角度，提出了一种基于马尔科夫重生过程(MRGP)的普适计算系统可用性度量方法，以解决关联用户的普适计算系统可用性度量问题。建立了具有双扩展特点的用户模型，分析了用户行为特征；构建了普适计算系统可用性的MRGP模型，对可用性进行了随机过程分析，并给出了对应瞬态和稳态行为的度量方法；结合普适计算模式的特点，定义了普适计算系统请求可用性度量。进行了数值分析，评价了用户和系统参数等因素对普适计算系统可用性度量的影响。     

面向用户的普适计算系统可用性度量模型

普适计算模式追求随时随地的计算境界,对相关可用性管理提出了很高的要求。现有研究大多基于定性的角度研究普适计算系统的可用性问题,本文尝试给出定量的可用性度量模型和分析。普适计算系统可用性具有典型的面向用户特点,为刻画用户行为需要引入具有非指数分布性质的模型状态,并且需要考虑用户态与系统态关联分析时的复杂情况。传统的连续时间马尔可夫链和半马尔可夫过程都不能很好地对以上情况给与分析。鉴于此,本文提出了一种基于马尔可夫重生过程(MRGP)的普适计算系统可用性度量方法。首先建立具有双扩展特点的用户模型,基于此构建了普适计算系统可用性度量的MRGP模型,对可用性进行了随机过程分析,给出了对应瞬态和稳态行为的度量方法,结合普适计算模式的特点定义了普适计算系统请求可用性度量。最后进行了数值分析,评价了用户和系统参数等因素对普适计算系统可用性度量的影响。     

Performance analysis of distributed real-time databases

In a distributed process control system, information about the behavior of physical processes is usually collected and stored in a real-time database which can be remotely accessed by human operators. In this paper we propose an analytic approach to compute the response-time distribution of operator consoles in a distributed process control environment. The technique we develop is based on Markov regenerative processes (MRGPs) and described with the assistance of deterministic and stochastic Petri nets (DSPNs). We construct exact models for performance analysis of centralized and decentralized database architectures. However, due to limitations on the exact solution, we also propose an approximate solution which is then used to study response-time distributions of large systems.     

Positive software fault-tolerate technique based on time policy

With the increase of the complication of computer systems, the loss which is caused by software inefficiency is more and more widespread. How to reduce the loss of systems to improve its reliability becomes the main problem. At present, software fault-tolerate technique is the most effective approach to solve this problem. According to the development situation of software fault-tolerate technique, this paper proposes a new positive software fault-tolerate technique based on the analysis of traditional technologies, which is called software rejuvenation, and analyze the rejuvenation model based on time policy in detail.