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1.
潘理  郑红  杨勃  周新民 《计算机科学》2014,41(12):202-205,230
针对时间Petri网现有强、弱语义模型在调度分析上存在的缺陷以及凝练调度一致性问题和调度时限性问题,提出混合语义模型解决方案,并给出混合语义模型的特征条件,比较混合语义模型与强、弱语义模型的时间互模拟能力,证明混合语义模型的正确性和时间行为的不可替代性。  相似文献   

2.
基于Time Petri Nets的实时系统资源冲突检测   总被引:2,自引:1,他引:1  
Time Petri Nets在实时系统的建模和性能分析中得到广泛应用,而冲突是Petri网及其扩展模型的重要行为,解决冲突是正确分析模型动态行为的关键.目前随机Petri网、混合Petri网和区间速率连续Petri网的冲突检测方法由于没有考虑到时间约束因此无法在TPN网中使用.时间约束的引入使得Time Petri Nets模型的使能和触发语义比Petri网模型的语义复杂,冲突检测变得更加困难.为了计算冲突发生的时间和概率,首先根据时间约束,给出了变迁持续使能时延迟区间的计算方法,并证明了该方法的合理性和完备性;然后在此基础上定义并证明了Time Petri Nets模型中不冲突的检测方法;并提出了Time Petri Nets模型的冲突检测方法,给出了冲突时间区间和变迁实施概率的计算方法;最后通过实例验证说明了该方法的正确性和有效性.  相似文献   

3.
时间约束Petri网(Timing Constraints Petri nets,简称TCPNs)是一类重要的时间Petri网系统.针对TCPNs中变迁可调度原始语义的不足,本文对相关定义重新定义,丰富并完善了TPCNs理论.本文首先给出了新的针对单个变迁或变迁序列的可调度分析策略.如果一个特定的变迁序列是可调度的,则相应的活动序列也同样可以顺利地完成自身的执行;否则,不可调度的变迁需要调整自己的时间约束;然后提出了组合式的可调度分析策略以分析复杂变迁序列,最后提出时序一致性的概念.  相似文献   

4.
时间Petri网存在强语义和弱语义两种模型,弱语义模型更适合建模和分析外部环境触发的冲突选择问题,但其形式语义和可达性分析方面的研究,却很少有人问津。利用带标号的变迁系统定义时间Petri网弱语义模型的形式语义,采用时间戳状态类方法分析它的可达性,并证明了可达性问题的可判性和状态类时间戳的全局时间性质。  相似文献   

5.
一种面向DRM的责任授权模型及其实施框架   总被引:2,自引:0,他引:2  
钟勇  秦小麟  刘凤玉 《软件学报》2010,21(8):2059-2069
针对现有的DRM(digital rights management)机制缺乏真正的责任描述和实施能力问题,提出一种应用于DRM的责任授权模型及其实施框架.该模型基于分布式时态逻辑和Active-U-Datalog语法规则,具有表达事件驱动、时间驱动和责任补偿等各类责任授权的语义能力,并具有良好的可实施性.对该模型的语法语义进行了分析和说明,描述了责任实施机制,并对该模型的实现、应用和表达力进行了说明和示例.该模型提高了DRM系统对数据使用控制的灵活性和能力.  相似文献   

6.
设计资源的有限性和设计活动的并发性会导致产品协同设计过程中的资源冲突.针对具有时间属性的产品协同设计过程资源约束的可调度性问题,采用时间约束Petri网理论提出一种产品协同设计过程资源约束网模型,定义了具有单一资源库所输入和多个资源库所输入的设计活动变迁的可调度性概念及其判定规则.把协同设计的资源约束可调度性划分为弱可调度和强可调度2类,通过引入变迁序列的token到达资源库所时间上下界的概念,给出了产品协同设计过程资源约束的可调度性规则及算法.最后通过一个链式输送机传动系统的协同设计资源约束模型,验证了文中方法的有效性.  相似文献   

7.
针对分布式系统在共享资源冲突和消解的复杂性问题,综合考虑时间、空间、约束条件等因素,在混合Petri网同时具备描述离散系统和连续系统的能力的基础上,加入时间约束条件、测试孤,从而形成一个能够描述更复杂分布式系统的Petri网模型.利用Petri网描述系统的基本思想,经过扩展得出新模型,变迁使能、变迁触发和变迁冲突检测的定义.结合实例,对模型进行了仿真分析,给出了实例中系统冲突的消解方案,表明了模型的可行性.  相似文献   

8.
为了提高煤矿井下机车调度效率和实现井下调度系统自动化,基于Petri网理论知识结合实际井下矿场路况建立机车调度Petri网模型,然后对Petri网模型添加限制库所和变迁使其调度过程无死锁,并通过理论证明了该调度模型是无死锁和冲突的,可以指导机车井下运输调度.然后在机车调度规则下针对不同的井下机车调度相关参数,提出了3种不同情况下的机车最优调度策略,并通过验证实际矿场参数后的分析证明了该调度策略下机车的调度是不触发死锁情况下的最优调度.最后通过仿真实验以及实际应用证明了该调度策略的正确性和完备性,为井下运输的自动调度提供了理论基础.  相似文献   

9.
为了提高晶圆制造中组合设备的生产效率,在考虑晶圆驻留时间约束条件下,研究没有共享加工模块的多品种晶圆混合加工的单臂组合设备调度问题.首先,采用面向资源的Petri网模型描述多种晶圆产品的混合加工过程,引入控制变迁避免模型的死锁,采用赋时库所和赋时变迁模拟系统资源的活动时间.其次,通过虚拟加工的方法平衡工序的负载,基于系统Petri网模型和拉式调度策略,推导出单臂组合设备在多品种晶圆混合加工情形下的可调度性判定条件,并以解析形式描述.最后,提出了系统稳态调度求解算法并以实例验证了算法的有效性和可行性.  相似文献   

10.
为了增强混杂Petri网解决资源共享和资源冲突的能力,定义一种新的混杂Petri网模型———资源配置混杂Petri网,提出了相应的使能和激发规则.将对连续变迁和离散变迁的控制作用引入混杂Petri网,同时,增加了资源配置变迁和资源释放变迁,用于有效分配可重复利用的资源.以典型的混杂生产过程为例,研究混杂系统生产过程建模.研究结果表明,所定义的模型描述能力强,模型语义正确合理,能够有效描述和分析混杂系统生产过程.  相似文献   

11.
袁春  陈意云 《计算机学报》2000,23(8):877-881
针对一个基于共享变量的带有进程创建的命令式语言,用变迁系统描述了它的结构操作语义,并用扩展的状态变迁迹模型定义了它的指称语义,在该模型下,状态变迁被区分为两种不同形式,分别表示发生在原进程和被创建进程中的状态变迁,这样便可以定义适当的语义复合运算,在对命令的指称进行复合时根据变迁类型的不同对变迁迹进行串行或交错连接,恰当地反映了进程的并发运行受创建命令在程序中的相对位置的限制,最后证明了这两个语义  相似文献   

12.
13.
The transition set semantics (Wang and Jiao, LNCS 6128:84–103, 2010) partitions the Petri net behaviors in a canonical way such that behaviors in an equivalence class have the same canonical transition set sequence. This article extends the semantics in two ways: firstly, the semantics is parameterized by the basic relation on the structural transitions to define different variants; secondly, the semantics for the infinite firing sequences of the net is defined. We prove that these extensions still preserve the well-definedness, soundness and completeness of the semantics. Furthermore, we show how to recognize some infinite sequences called back-loops in the view of this new semantics.  相似文献   

14.
SIGNAL is a part of the synchronous languages family, which are broadly used in the design of safety-critical real-time systems such as avionics, space systems, and nuclear power plants. There exist several semantics for SIGNAL, such as denotational semantics based on traces (called trace semantics), denotational semantics based on tags (called tagged model semantics), operational semantics presented by structural style through an inductive definition of the set of possible transitions, operational semantics defined by synchronous transition systems (STS), etc. However, there is little research about the equivalence between these semantics. In this work, we would like to prove the equivalence between the trace semantics and the tagged model semantics, to get a determined and precise semantics of the SIGNAL language. These two semantics have several different definitions respectively, we select appropriate ones and mechanize them in the Coq platform, the Coq expressions of the abstract syntax of SIGNAL and the two semantics domains, i.e., the trace model and the tagged model, are also given. The distance between these two semantics discourages a direct proof of equivalence. Instead, we transformthem to an intermediate model, which mixes the features of both the trace semantics and the tagged model semantics. Finally, we get a determined and precise semantics of SIGNAL.  相似文献   

15.
传值系统的互模拟与谓词等式系   总被引:3,自引:0,他引:3  
林惠民 《计算机学报》1998,21(2):97-102
本文引入描述传值并系统的新模型“带赋值符号迁移图(STGA)”推广了Hennessy和Lin提出的“符号迁移图”的概念,允许迁移上带有赋值,从而能将更大的一类传值系统表示为有穷状态图,STGA的中车优点是在并行运算不封闭,文中给给STGA的操作语义,在此基础上定义了STGA的互模拟等价关系,为了刻划STGA的互模拟,以谓词等式系的形式在一阶逻辑的正子集中扩充了最大和最小不动点,并设计了一个算法将S  相似文献   

16.
17.
Petri nets in which random delays are associated with atomic transitions are defined in a comprehensive framework that contains most of the models already proposed in the literature. To include generally distributed firing times into the model one must specify the way in which the next transition to fire is chosen, and how the model keeps track of its past history; this set of specifications is called an execution policy. A discussion is presented of the impact that different execution policies have on semantics of the mode, as well as the characteristics of the stochastic process associated with each of these policies. When the execution policy is completely specified by the transition with the minimum delay (race policy) and the firing distributions are of the phase type, an algorithm is provided that automatically converts the stochastic process into a continuous time homogeneous Markov chain. An execution policy based on the choice of the next transition to fire independently of the associated delay (preselection policy) is introduced, and its semantics is discussed together with possible implementation strategies  相似文献   

18.
Model Checking of Time Petri Nets Using the State Class Timed Automaton   总被引:2,自引:0,他引:2  
In this paper, we propose a method for building the state class graph of a bounded time Petri net (TPN) as a timed automaton (TA), which we call the state class timed automaton. We consider bounded TPN, whose underlying net is not necessarily bounded. We prove that our translation preserves the behavioral semantics of the TPN (the initial TPN and the obtained TA are proved timed-bisimilar). It allows us to check real-time properties on TPN by using the state class TA. This can be done efficiently thanks to a reduction of the number of clocks. We have implemented the method, and give some experimental results illustrating the efficiency of the translation algorithm in terms of number of clocks. Using the state class TA, we also give a framework for expressing and efficiently verifying TCTL properties on the initial TPN.  相似文献   

19.
Mobile agents, i.e. pieces of programs that can be sent around networks of computers, appear more and more frequently on the Internet. These programs may be seen as an enrichment of traditional distributed computing, and structuring applications using mobile agents is destined to become the de facto way of constructing distributed systems in the near future. Since mobile agents may carry communication links with them as they move across the network, they create very dynamic interconnectio n structures that can be extremely complex to analyse. In this paper we study an example of a system based on the mobile agent principle, written in the Facile programming language. We propose a Structural Operational Semantics (SOS) for Facile, giving a proved transition system that records encodings of the derivation trees of transitions in their labels. This information enables us to easily recover non-interleaving semantics for Facile by looking only at the labels of transitions. We use the new semantics to debug an agent based system. This example is a scaled down version of a system demonstrated at the European IT Conference Exhibition in Brussels, 1995. We also adopt our causal semantics to analyse the specification of a prefetch pipeline processor. Received: 14 November 1997 / 30 April 1999  相似文献   

20.
We present a framework for performance prediction of distributed and mobile systems. We rely on process calculi and their structural operational semantics. The dynamic behaviour is described through transition systems whose transitions are labelled by encodings of their proofs that we then map into stochastic processes. We enhance related works by allowing general continuous distributions resorting to a notion of enabling between transitions. We also discuss how the number of resources available affects the overall model. Finally, we introduce a notion of bisimulation that takes stochastic information into account and prove it to be a congruence. When only exponential distributions are of interest our equivalence induces a lumpable partition on the underlying Markov process.  相似文献   

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