【作者】 邹峥；

【导师】 乐晓波；

【作者基本信息】 长沙理工大学 ， 计算机应用技术， 2010， 硕士

【摘要】 随着软件系统应用范围的日趋广泛,我们的日常生活越来越依赖应用软件所提供的服务,目前软件已经应用于航空航天、核电技术、军事、电子机械、金融等许多重要的特殊工程领域,在这些应用领域里,一个小的软件故障可能会导致灾难性的生命和财产损失。同时随着近年来软件规模越来越大,软件系统的复杂性也急剧地增加,解决软件可靠性问题变得越来越迫切。软件可靠性分析主要分为软件可靠性建模和可靠性指标分析。其中软件可靠性建模在可靠性分析起着核心的作用,目前所提出的模型大部分是基于故障树进行分析,不能全面地描述系统的动态行为,因而存在一定的应用范围和条件的局限性,不能很好地适应复杂多变的应用环境的需求;在可靠性指标分析方面,目前的计算方法大多只能针对失效的稳定状态进行可靠性分析,因此无法掌握整个系统的可靠度动态的变化趋势;此外,大多数软件失效是随机的、间歇的,软件可靠性模型在形式上符合随机过程的特性,这使得在可靠性分析中,时间比其他的特性更加重要。本文首先把随机Petri网应用于可靠性建模,随机Petri网把时间参数与变迁关联,有助于定义可靠性模型的动态行为。同时本文通过比较随机Petri网及软件可靠性技术的概念、特点及它们之间的关系,从软件故障产生与传递的表述方面着眼给出了具体的可靠性建模方法;然后,针对随机Petri网应用中常常会碰到的复杂的空间爆炸问题给出了两种解决方案;其次,引入了一种计算瞬时可靠度的方法对简化后的随机Petri网进行分析,提高了评价和预测可靠性的精确度和正确性,并且所获得的结果有助于实时监控软件运行一定时间内的可靠性变化情况,从而可以指导可靠性设计的后期开发;最后,通过实验结果验证了该可靠性分析方法的可行性及有效性。更多还原

【Abstract】 With increasing scale of softwares, the service largely depends on applied softwares in our daily life. Some softwares now are applied to special fields, such as air industry, nuclear power technology, military industry, electron mechanism and banks. The failure of softwares will contribute to big loss of lives and money. The reliability of the software crys for being solved with the increasing scale and complexity.The work of software reliability analysis includes modeling software reliability and analysing software indexs, and the reliability model is very important. The present models mainly analyse with the failure tree, it can not describe the whole dynamic action, so it can not adapt to the quick changing environment and is restricted; Concerning the analyzing software indexs, most of calculating methods are used to analyse the failure of steady state, it makes us can not seize changing current of reliability; Besides, most of software failure are stochastic and interim ,then reliability model is formally a stochastic process, it makes time be much more important than defining dynamic logic.Firstly, the Stochastic Petri Net is applied to reliability model. It can help define dynamic action with relation between transition and time. Meanwhile, the detailed reliability model method is given with comparing concepts ,traits and relation between Stochastic Petri Net and software reliability; secondly, two methods are given in the paper to solve the state space explosion problem ; Thirdly, a method of calculating instantaneous reliability is introduced to analyse the simplified Stochastic Petri Net, it improves precision of model and can guide the reliability design; finally, the feasibility and validity are verified by the test.更多还原