共查询到20条相似文献,搜索用时 46 毫秒
1.
《Journal of computational science》2013,4(3):170-179
The paper presents a grammar for anisotropic two-dimensional mesh adaptation in hp-adaptive Finite Element Method with rectangular elements. Expressing mesh transformations as grammar productions is useful for concurrency analysis thanks to exhibiting the partial causality order (Lamport relationship) between atomic operations. It occurs that a straightforward approach to modeling this process via grammar productions leads to potential deadlock in h-adaptation of the mesh. This fact is shown on a Petri net model of an exemplary adaptation. Therefore auxiliary productions are added to the grammar in order to ensure that any sequence of productions allowed by the grammar does not lead to a deadlock state. The fact that the enhanced grammar is deadlock-free is proven via a corresponding Petri net model. The proof has been performed by means of reachability graph construction and analysis. The paper is concluded with numerical simulations of magnetolluric measurements where the deadlock problem occurred. 相似文献
2.
Yubin Zhong 《Fuzzy Optimization and Decision Making》2008,7(4):399-408
This paper designs a class of Fuzzy Petri net controller based on the character of place invariant in Petri net. This controller
is simple in operation and is easy to put into practice. It has satisfying effects and can provide methods to do research
in designing and optimizing the performance of system in solving the dead lock phenomenon in concurrent system. 相似文献
3.
Automata with concurrency relations are labelled transition systems with a collection of state-dependent binary independence relations for the actions. We show how to associate with each Petri net (place/transition net) such an automaton having the same dynamic behaviour. We characterize the automata arising in this way, and with suitable notions of morphisms for Petri nets and for automata with concurrency relations we extend this correspondence to a coreflection between the associated categories. As a consequence, we derive that these categories have products and conditional coproducts. 相似文献
4.
基于Petri Net的需求流动网组建模型及其稳定性分析 总被引:1,自引:0,他引:1
针对供应链概念不足,提出需求流动网概念,并论述了需求流动网概念模型,运用Petri网理论建立需求流动网模型,并对模型进行了分析,随后在分析需求流动网稳定性内涵的基础上,进一步运用Petri网理论分析了需求流动网稳定性,并最终得出了相应结论. 相似文献
5.
针对装备的战场抢修要求恢复状态可以具有多样性的特点,对原有模型进行了改进,提出了模糊随机Petri网模型,并且验证了模型实用性和有效性. 相似文献
6.
Petr Fiala 《Central European Journal of Operations Research》2012,20(3):383-392
Revenue management is the process of understanding, anticipating and influencing consumer behavior in order to maximize revenue. Network revenue management models attempt to maximize revenue when customers buy bundles of multiple resources. The dependence among the resources in such cases is created by customer demand. Network revenue management can be formulated as a stochastic dynamic programming problem whose exact solution is computationally intractable. Solutions are based on approximations of various types. Customer choice behavior modeling has been gaining increasing attention in the revenue management. A framework for solving network revenue management problems with customer choice behavior is proposed. The modeling and solving framework is composed from three inter-related network structures: basic network model, Petri net, and neural net. 相似文献
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Modeling the controller of the railway network, having resource sharing based on mutual exclusion constraints, is an important problem. This paper firstly addresses the specification of safety properties for the model of a complex railway crossing. The operations, i.e., occupied, free and block, are formalized to describe the safety properties along railway crossing. Second, to develop the control model of the crossing system we construct the subnet representing the train flow along the tracks in the crossing region and the set of monitors or supervisors are also modeled as subnets. Arc-constant colored Petri net (ac-CPN) is used to construct the train flow subnet while the monitors are modeled using the place/transition-net. Arc-constant colored Petri net enforces the specification of not to shift the train from a track to another one. Bottom-up approach is adopted to model the control for railway crossing as a synchronous synthesis of the subnets is applied to build the final model. Finally, to verify the safety properties in the developed controller, the coverability tree method is used for the analysis of the final model. 相似文献
9.
提出基于奇偶校验的方法对Petri网控制器进行故障检测.设计出满足包含标识向量和Parikh向量的线性约束的Petri网控制器;建立一个包含一定数量库所的附加Petri网控制器以满足奇偶校验的编码要求;分别针对库所故障和变迁故障,选用不同的奇偶校验参数进行故障检测,并通过实例详细阐明了故障检测的过程. 相似文献
10.
Q. JinY. Sugasawa 《Mathematical and Computer Modelling》1995,22(10-12)
This paper proposes a new approach to visually represent the behavior of multiprocess in a computer network system using stochastic Petri net (SPN) and an aggregate approach of SPN and Markov renewal process (MRP) to conduct behavior analysis and performance evaluation for the system. SPN is employed because of its highly visual nature that can give insight into the nature of the modeled system and because of its expressive power for an exponentially distributed event. In order to increase the analytical power of the SPN model, MRP is introduced and an embedded transference probability matrix is applied to obtain the steady-state solution of the model, from which it is possible to obtain automatically the performance measures of the multiprocess computer network system. 相似文献
11.
提出了用Petri网建立工程管理模型.为了适应在工程管理中的应用,对Petri网理论进行了扩充,提出了判定库所的概念,设计了托肯移动的规则,使用优先矩阵描述了托肯的移动. 相似文献
12.
Rapid and modular prototyping-based Petri nets and distributed simulation for manufacturing systems 总被引:6,自引:0,他引:6
This paper presents an approach to simulate and implement by stepwise refinement the whole manufacturing system (MS) by means of distributed simulation. This approach is based on the use of different classes of Petri nets to model different levels of a manufacturing system. Furthermore these classes may match the abstraction levels of a high-level Petri net used to model the MS. Each level can be simulated on a processor or a cluster of processors which can communicate between themselves using a network. The main contribution is to give the opportunity to combine simulation, performance evaluation and emulation. The emulation means that a part of the system can be run in real time while the other part is simulated. Moreover based on the abstraction levels of high-level Petri nets, subsystems can be integrated step-by-step from the design stage to the implementation one, allowing inter-changeability between simulated components and real-time physical systems. This approach is achieved by defining a simulation engine which involves a local simulator, an emulator and an interface to the physical process. Criteria are defined to use an emulator or a local control software for a physical process as a logical process for the conservative distributed simulation. 相似文献
13.
A new nonlinear interval programming method for uncertain problems with dependent interval variables
This paper proposes a new nonlinear interval programming method that can be used to handle uncertain optimization problems when there are dependencies among the interval variables. The uncertain domain is modeled using a multidimensional parallelepiped interval model. The model depicts single-variable uncertainty using a marginal interval and depicts the degree of dependencies among the interval variables using correlation angles and correlation coefficients. Based on the order relation of interval and the possibility degree of interval, the uncertain optimization problem is converted to a deterministic two-layer nesting optimization problem. The affine coordinate is then introduced to convert the uncertain domain of a multidimensional parallelepiped interval model to a standard interval uncertain domain. A highly efficient iterative algorithm is formulated to generate an efficient solution for the multi-layer nesting optimization problem after the conversion. Three computational examples are given to verify the effectiveness of the proposed method. 相似文献
14.
Zvi Retchkiman Knigsberg 《Nonlinear Analysis: Hybrid Systems》2008,2(4):1205-1216
In this paper, an algorithm for computing a generalized eigenmode of reducible regular matrices over the max-plus algebra is applied to the Metro-bus public transport system in Mexico city. A timed event Petri net model is constructed from the data table that characterizes the transport system. A max-plus recurrence equation, with a reducible and regular matrix, is associated with the transport system timed event Petri net. Next, given the reducible and regular matrix, the problem consists of giving an algorithm which will tell us how to compute its generalized eigenmode over the max plus algebra. The solution to the problem is achieved by studying some type of recurrence equations. In fact, by transforming the reducible regular matrix into its normal form, and considering a very specific recurrence equation, an explicit mathematical characterization is obtained, upon which the algorithm is constructed. The generalized eigenmode obtained sets a timetable for the transport system. 相似文献
15.
《Mathematical and Computer Modelling》1998,27(4):137-150
We propose a model of an age-structured population divided into N geographical patches. We distinguish two time scales, at the fast time scale we have the migration dynamics and at the slow time scale the demographic dynamics. The demographic process is described using the classical McKendrick-von Foerster model for each patch, and a simple matrix model including the transfer rates between patches depicts the migration process.Assuming that 0 is a simple strictly dominant eigenvalue for the migration matrix, we transform the model (an e.d.p. problem with N state variables) into a classical McKendrick-von Foerster model (scalar e.d.p. problem) for the global variable: total population density. We prove, under certain assumptions, that the semigroup associated to our problem has the property of positive asynchronous exponential growth and so we compare its asymptotic behaviour to that of the transformed scalar model. This type of study can be included in the so-called aggregation methods, where a large scale dynamical system is approximately described by a reduced system. Aggregation methods have been already developed for systems of ordinary differential equations and for discrete time models.An application of the results to the study of the dynamics of the Sole larvae is also provided. 相似文献
16.
Adaptation as a Morphing Process: A Methodology for the Design and Evaluation of Adaptive Organizational Structures 总被引:1,自引:0,他引:1
Changes in objectives, in resources, or in the environment may necessitate the adaptation of an organization from one form to another. However, in many cases, the organizations need to continue functioning while adaptation takes place, i.e., it is not possible to stop the organizational activity in order to reorganize, and then start again. In this case, adaptation can be expressed as a morphing process in which the organization transitions from one form with its attendant task allocation to a different one through a series of incremental steps that preserve overall functionality and performance. Coordination between organization members during adaptation is critical. A computational model for this type of organizational adaptation at the operational level is presented. The model is implemented using the Colored Petri Net formulation of discrete event dynamical systems. A design methodology that utilizes this model is outlined and a simple example is used to illustrate the approach. 相似文献
17.
Redouane Kara Jean Jacques Loiseau Said Djennoune 《Nonlinear Analysis: Hybrid Systems》2008,2(4):1010-1020
This paper deals with the computation of the asymptotic firing rate vector and the stationary marking of continuous weighted marked graphs under infinite servers semantics. The continuous weighted marked graphs are a particular class of continuous Petri net where each place has exactly one input and one output transition. First, we give an explicit formula to compute the asymptotic firing rate vector of transitions using the structure of the given net. Then, under the assumption that there exists only one critical circuit in the strongly connected continuous neutral weighted marked graphs, an original approach to compute the vector of stationary marking is presented. Finally, an application to a flexible manufacturing system is given. 相似文献
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讨论了供应链网络中如何选择优化路径的问题,提出采用时间P etri网对供应链网络关键路径建模的方法.此方法根据顾客需要货物的情况,有条件地选取供应链网络图中可跨越活动和可替换分支,将网络图分别描述成Ebs图和Ew f图,结合时间P etri网的可达算法,求得Ebs和Ew f的关键路径.通过基本供应链的分析,得到网络的优化路径. 相似文献
20.
为了解决矿尘连续排放并迁移对地表生态系统造成的脆弱性问题,提出了基于函数地理Petri网的脆弱性级联传播模型。综合考虑污染物迁移方向和生态环境在地理空间上的关联关系,直观地构造了基于级联传播的污染Petri网。在此基础上,定义了基于VCPM的脆弱度和阈值的概念,利用两者的关系进行脆弱性级联传播分析,从而明确级联传播的三种状态。最后,以神府煤田矿尘迁移作为污染物连续排放的污染源,通过模型方法的模拟仿真分析,对生态环境系统在级联传播下的脆弱性进行了深入探讨。已有的研究方法和结果不仅在生态环境脆弱性研究领域做出了新的贡献,而且为环境的修复和重建提供了参考价值。 相似文献