共查询到19条相似文献,搜索用时 140 毫秒
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Web服务器集群请求分配和选择的性能分析 总被引:31,自引:2,他引:29
讨论并提出了 Web服务器集群的请求分配和选择控制方案 ,而且提供了这些方案的随机高级 Petri网模型 ,并强调研究这些方案及性能模型和分析方法 .为解决模型状态空间爆炸问题 ,作者提出了一种近似性能分析技术 ,可以显著地简化模型求解的复杂性 .文中的 Web服务器集群模型、请求分配和选择控制方案及近似性能分析技术可以应用于这类复杂系统的性能评价 . 相似文献
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通过分析服务器群集系统的结构和工作原理,采用随机Petri网分别建立基本处理单元的软硬件可用性模型、共享数据磁盘可用性模型和服务器可用性模型。综合各个模型,得到服务器集群系统的可用性模型,通过仿真分析可知,采用集群技术可以有效提高服务器的可靠性。 相似文献
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本文探讨了利用随机Petri网进行系统性能评价的方法,包括随机砌一网的建模过程、模型的精化、近似求解。采用局域Web服务器集群系统HTTP请求分配和选择的综合方案为具体算例实现。 相似文献
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基于混合自动机的随机噪声电路动态特性分析 总被引:1,自引:0,他引:1
在集成电路非线性随机噪声的分析中应用Petri网技术,需要对原有的Petri网从定义和变迁发射规则方面等进行统计特性与连续特性的拓展研究和补充.并且基于噪声的随机非线性特性分析目的需求,拓展了传统的Petri网,提出了混合随机Petri网(Hybrid Statistical Petri Net,HSPN)模型分析方法.通过分析非线性电路的混合自动机模型,增加Petri网随机参数变迁描述能力,针对电路噪声特点,确定适合HSPN的随机动态特性分析模型.通过实例电路说明验证HSPN的建模方法,并与SPICE仿真软件进行比较,验证了该方法的精度和可行性. 相似文献
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为解决松耦合Web事务复杂业务流程的建模问题,确保组合事务的可靠性和一致性,提出一种基于配对Petri网的结构化组合补偿精化方法,实现复杂多伙伴业务流程的抽象层次建模.定义了4种基于配对Petri网的基本组合补偿结构:顺序、并行、选择和循环结构.引入组合流程精化和组合补偿抽象的定义,分析了复杂业务流程的精化和抽象过程,给出了精化流程应满足的性质.通过具体业务实例验证了该精化和抽象方法的可行性. 相似文献
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为了更好地刻画单个Asent的行为和多Asent间复杂、并行的动态交互,将面向Agent的设计思想与Petri网建模方法相结合,形成了一种面向Agent的Petri网(AOPN)模型.首先给出了面向Agent的Petri网的形式化定义,然后利用Petri网的建模工具,以网上购物背景下买卖双方简单交互为例,对基于面向Agent的Petri网模型的系统建模方法进行了研究和分析,有效地解决了系统结构复杂性的问题. 相似文献
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基于Petri网化简技术的工作流过程模型结构验证 总被引:2,自引:1,他引:1
目前,工作流系统向大型化发展,这使得基于可达图的验证技术在对大型模型进行验证时面临着状态空间爆炸的问题.因此,在过程验证之前,对大型模型进行化简是必要的.文中介绍两种化简规则.这些规则将一个大的Petri网化简为更小的Petri网,同时保持合理性属性,保证化简后的Petfi网和原有的Petri网具有相同的属性.介绍了Petri网、Workflow Petri网和过程合理性定义;讨论了针对Petri网的两种化简技术;提出了工作流过程模型结构合理性验证过程. 相似文献
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M. Ajmone Marsan
S. Donatelli
F. Neri
《Performance Evaluation》1990,11(4):227-240The paper presents exact results for the average customer waiting and sojourn times in Markovian systems comprising a number of finite-capacity queues cyclically attended by several servers. The system behaviour is described using generalized stochastic Petri nets (GSPN), and the performance indices are obtained numerically by means of GreatSPN, the software tool for the analysis of GSPN. The average waiting and sojourn times of customers in Markovian multiserver multiqueue systems are computed exactly in this paper for the first time: they were previously estimated for similar systems by other authors only through approximate models. 相似文献
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An iterative technique for the computation of approximate performance indices of a class of stochastic Petri net models is presented. The proposed technique is derived from the mean value analysis algorithm for product-form solution stochastic Petri nets. In this paper, we apply the approximation technique to stochastic marked graphs. In principle, the proposed technique can be used for other stochastic Petri net subclasses. In this paper, some of these possible applications are presented. Several examples are presented in order to validate the approximate results 相似文献
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Nondeterministic Probabilistic Petri Net — A New Method to Study Qualitative and Quantitative Behaviors of System 下载免费PDF全文
There are many variants of Petri net at present,and some of them can be used to model system with both function and performance specification,such as stochastic Petri net,generalized stochastic Petri net and probabilistic Petri net.In this paper,we utilize extended Petri net to address the issue of modeling and verifying system with probability and nondeterminism besides function aspects.Using probabilistic Petri net as reference,we propose a new mixed model NPPN(Nondeterministic Probabilistic Petri Net) system,which can model and verify systems with qualitative and quantitative behaviours.Then we develop a kind of process algebra for NPPN system to interpret its algebraic semantics,and an actionbased PCTL(Probabilistic Computation Tree Logic) to interpret its logical semantics.Afterwards we present the rules for compositional operation of NPPN system based on NPPN system process algebra,and the model checking algorithm based on the action-based PCTL.In order to put the NPPN system into practice,we develop a friendly and visual tool for modeling,analyzing,simulating,and verifying NPPN system using action-based PCTL.The usefulness and effectiveness of the NPPN system are illustrated by modeling and model checking an elaborate model of travel arrangements workflow. 相似文献
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生产系统的Petri网模型 总被引:5,自引:0,他引:5
本文提出了有消解过程的系统建模方法,并为随机模型建立了逐步精细原则,展示了系统性能分析的实例,探讨了建立外部监控模型的原理,研究了调控模型智能化问题,引入了用智能方法实现理想外部监控器的研究结果。 相似文献
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随机Petri网是一种系统设计和分析工具,它可以对系统进行定性分析和定量分析。为了有效利用随机Petri网进行性能的定量分析,根据随机Petri网模型转换为马尔可夫链的算法,总结并实现了它们之间的转换规则。该转换规则在变迁实施的过程中引入演变规则和合并规则,将随机Petri网模型转换为马尔可夫链。可以利用产生的马尔可夫链对随机Petri网模型的多项性能指标进行定量分析。实验结果表明,转换规则是正确、可行的。 相似文献
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基于Petri网的工作流过程模型及资源分布分析 总被引:1,自引:0,他引:1
针对工作流系统的特点对时延Petri网模型进行扩展,提出了一种新的工作流建模方法,即扩展时延Petri网。给出了扩展时延Petri网的定义,并用该方法分析了工作流四种基本模型;给出了利用排队论和随机Petri网理论计算工作流模型时间性能指标的新方法,用这种方法可求得与实例到达率相关的工作流模型平均完成时间。最后应用上述方法讨论了工作流资源分布的几种模式,并与模拟结果加以对比,计算结果的最大误差在3%左右,说明基于扩展时延Petri网的方法是分析工作流系统时间性能的有效方法。 相似文献
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A general method is proposed for the performance evaluation of a decision-making architecture for computer-integrated manufacturing systems. A decision-making architecture broadens the concept of a control architecture by integrating control, communication and database functions. A modular modeling methodology is developed that captures these features and is applicable to an arbitrary computer-integrated manufacturing architecture. The model is based on generalized stochastic Petri nets and leads to a quantitative evaluation of such performance measures as response time, average utilization of a particular system component, average queue length, etc. The net result is a design tool that can be used to make tradeoffs among the system parameters.
The proposed technique is demonstrated using several real-time decision-making architectures. Several general conclusions are drawn from this investigation. Finally, a Petri net model reduction method is presented for this problem and used to compare the original performance evaluation results with those obtained from the simplified models. 相似文献
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