共查询到18条相似文献,搜索用时 296 毫秒
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一种随机Petri网性能等价化简与分析方法 总被引:24,自引:0,他引:24
随机Petri网模型是系统性能评价的有力工具,但其状态空间随模型规模的增长而指数性增长的问题限制了其对复杂和大规模系统模型的性能数量分析能力.因此,在对模型进行分析之前,先对其进行适当的性能等价化简,是一种更为可行的分析方法.本文首先讨论了一类随机Petri网-基本随机Petri网(ESPN)的性能等价分析方法,这类随机Petri网由顺序、并行、选择和循环等四种基本结构及其组合构成.作者推导出这四种基本结构的性能等价公式,并运用自底向上逐步综合替代的分层分析方法,给出这类随机Petri网模型的性能等价化简分析方法,该方法的复杂性随模型增长而线性增长,有效解决了其性能数量分析问题.然后,讨论了两种非基本结构到基本结构的转换规则,使得复杂的随机Petri网模型也可能转换为ESPN模型,从而使性能等价算法可应用于一般随机Petri网. 相似文献
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随机高级Petri网在异构系统中的应用 总被引:1,自引:0,他引:1
传统的随机高级Petri网(Stochastic high-level Petri nets,SHLPNs)通过将多个同构子系统压缩成一个子系统,并将具有相同标记分布的多个标识压缩成一个标识(复合标识),从而有效地减小模型规模和状态空间.但该方法仅适用于若干同构子系统组成的系统中,本文将这种方法扩展,通过引入非对称的变迁实施谓词和扩展的复合标识,精确地模型并分析异构系统,同时也保持了SHLPNs在化简模型和状态空间方面的优越性. 相似文献
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含有非马尔可夫过程的排队Petri网模型和性能分析 总被引:6,自引:0,他引:6
本文提出了一种新的高级性能模型技术,称作NM-QPN(含有非马尔可夫过程的排队Petri网,Queuing Petri Net including Non-Markovian processes),它综合了排队网,随机Petri网以及模拟求解各自的特点.NM-QPN以模拟模型为总体框架,发挥排队网和随机Petri网各自的优势对系统进行建模.提出了一套完整的NM-QPN模型求解方案,通过流等价方法将模型中的马尔可夫过程进行化简,这样可以大大减少模型的状态,最后再用模拟求解方法求解剩下的非马尔可夫过程. 相似文献
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Petri网的优化调度求解主要采用基于状态空间的智能搜索方法,执行效率往往不高.提出基于蚁群优化的时间Petri网,通过在Petri网的变迁和进化规则中引入蚁群优化机制,改变Petri网原有的非确定性选择行为,使之具备蚁群寻优选择智能行为,克服了需要基于状态空间进行启发式搜索的缺陷,提高了调度优化的计算效率.最后应用蚁群优化时间Petri网模型,对柔性制造系统的区间Job Shop调度问题进行建模和优化求解.实验结果进一步验证了所提模型和方法的有效性. 相似文献
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针对城市公交运行过程中紧急抢修故障车的效率问题,本文基于随机Petri网建立了城市公交运行故障的抢修模型,利用随机Petri网与马尔可夫链的同构关系,得到了抢修模型稳定的状态空间及各状态出现的概率,进而分析了抢修过程各环节的利用率及各状态的时间属性,为抢修效率的提高提供了相关依据.实例验证模型分析的有效性,通过对某些抢修环节的改善和提高,进而提高公交故障抢修的效率. 相似文献
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首次提出用随机Petri网为MapReduce逻辑模型建立Petri网模型的思想,目的在于采用随机Petri网工作流性质对其进行分析。因此,在研究MapReduce逻辑模型的基础上,为其建立了随机Petri网模型。该随机Petri网模型符合随机Petri网工作流系统的性质,本文利用随机Petri网的工作流系统的性能等价公式,分析了模型的性能,最终求出整个系统的性能参数。该性能参数能够很好地说明MapReduce处理大数据集的优势。 相似文献
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Stochastic Petri Nets have been developed to model and analyze systems involving concurrent activities. However, the firing times of a Stochastic Petri Net model are always exponentially distributed. This paper presents an aggregate approach on how to analyze Stochastic Petri Net model with non-exponential distributions using a generalized Markov Renewal Process. Therefore, the modeling flexibility of Petri Net and the analyzing power of Markov Renewal Process are fully exploited. Moreover, an Abstract Partial Reachability Graph is introduced to simplify the Markov solution. Furthermore, the aggregate approach is applied to evaluate performance of a parallel operation system. 相似文献
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The analysis of the behaviour of digital circuits, with special reference to signal propagation delays, is performed by means of the Petri Nets (PN) formal model. In particular, concurrent signal changes in the circuit which may give rise to possible functional errors such as races or hazards, are represented by this model. Moreover, the delays, assumed to be random variables with assigned probability distributions and Stochastic Petri Nets (SPN), which are an extension of classical PN's, are employed. By the resulting model, a great flexibility of representation is achieved, matching also the requisites of the particular technology employed.It is also possible to account for time varying inputs both in combinational and sequential circuits, reconvergent fanouts and conflicting events.The algorithm derived from this model allows to obtain a static logic verification of the circuit and exhibits shorter simulation times as compared to those of classical simulators. 相似文献
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随机高级Petri网用于计算机网络传输协议的模型与性能评价 总被引:9,自引:2,他引:7
本文讨论了具有标记变量的随机高级Petri网(SHLPN)以及标识类型,标记变量和等价标记变量的概念,给出了具有等价标记变量可达树构造算法,并证明了等价标记变量可达集与合并状态的马尔可夫链状态空间之间的同构。本文着重描述了SHLPN在计算机网络传输协议的模型与性能评价中扩,通过这个例子充分显示了这些概念和算法的有效性。 相似文献
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Stochastic Timed Petri Nets (STPNs) have been used to study the performance of various aspects of computer systems. We describe an innovative way to use these models to solve optimization problems. We outline the steps by which an STPN model can be employed to find the solution to the optimal directory placement problem. 相似文献
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Cognitive Radio (CR) system based on Orthogonal Frequency Division Multiple Access (OFDMA), such as Wireless Regional Area
Networks (WRAN) and Worldwide Interoperability for Microwave Access (WiMAX), often attempt to improve performance via dynamic
radio resource management, which is characterized as concurrent processing of different traffic and nondeterministic system
capacity. It is essential to design and evaluate such complex system using proper modeling and analysis tools. In the previous
work, most of the communication systems were modeled as Markov Chain (MC) and Stochastic Petri Nets (SPN), which have the
explicit limitation in evaluating adaptive OFDMA CR system with wide area traffic. In this paper, we develop an executable
top-down hierarchical Colored Petri Net (CPN) model for adaptive OFDMA CR system, and analyze its performance using CPN tools.
The results demonstrate that the CPN can model different radio resource management algorithms in CR Systems, and the CPN tools
require less computational effort than Markov model using Matlab, with its flexibility and adaptability to the traffics which
arrival interval and processing time are not exponentially distributed. 相似文献
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该文提出一种融合网格的下一代网络增值服务平台以解决下一代网络应用服务器的性能问题.该平台将下一代网络应用服务器中的增值业务以网格服务的形式进行封装,并为封装后的增值服务提供运行环境.平台采用一种基于网格技术的任务调度算法,通过利用现有网络上的处理能力以提高系统整体处理能力和性能.采用随机Petri网对平台进行建模,并进行性能仿真实验.实验结果说明本平台能较好地达到利用网络中空闲处理能力以提高系统整体性能的目标. 相似文献
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基于随机Petri网(SPN)模型方法,对LEO单层卫星网络进行了性能分析.首先建立了半双工通信模式下LEO单层卫星网络的SPN模型,并选取平均时延作为网络性能评价指标、采用SPNP6.0软件对该SPN模型进行了性能评价,分析了数据包到达速率、网络负载以及消息数等参数对网络平均时延的变化关系.该建模与性能评价方法将有助于卫星网络的构建和进一步的性能分析. 相似文献