USING COLORED-TIMED PETRI NET FOR THE SOLUTION OF DEADLOCK IN A FLEXIBLE ASSEMBLY SYSTEM

A colored timed Petri net(CTPN)modeling technique is developed for flexible assembly system(FAS) In particular,one section is devoted to the deadlock nodel based on the Petri net The rule of the deadlock error recovery is given Through the analysis of the behavioral properties of the FAS with the deadlock recovery model,the deadlock problem would be solved in the system.

Hierarchical Colored Timed Petri Nets for Maintenance Process Modeling of Civil Aircraft

Civil aircraft maintenance process simulation model is an effective method for analyzing the maintainability of a civil aircraft. First, we present the Hierarchical Colored Timed Petri Nets for maintenance process modeling of civil aircraft. Then, we expound a general method of civil aircraft maintenance activities, determine the maintenance level for decomposition, and propose the methods of describing logic of relations between the maintenance activities based on Petri Net. Finally, a time Colored Petri multi-level network modeling and simulation procedures and steps are given with the maintenance example of the landing gear burst tire of a certain type of aircraft. The feasibility of the method is proved by the example.

FINE-GRAINED DISTRIBUTED MULTIMEDIA SYNCHRONIZA-TION MODEL——ENHANCED FUZZY-TIMING PETRI NET

A fine grained distributed multimedia synchronization model——Enhanced Fuzzy timing Petri Net was proposed which is good at modeling indeterminacy and fuzzy. To satisfy the need of maximum tolerable jitter, the sufficient conditions are given in intra object synchronization. Method to find a proper granularity in inter object synchronization is also given to satisfy skew. Exceptions are detected and corrected as early as possible using restricted blocking method.

Verification of Session Initiation Protocol Using Timed Colored Petri Net

In this work, Session Initiation Protocol model is established by using Timed Colored Petri Nets (TCPN). SIP (Session Initiation Protocol) is a protocol developed to assist in providing advanced telephony services across the Internet. The Session Initiation Protocol (SIP) has become the quasi-standard for Voiceover-Internet Protocol (VoIP) communications. SIP is based on a client–server infrastructure in which user agents represent the end-terminals as clients, proxy servers handle SIP message routing between the user agents, and registrar servers store the client’s contact information into a location service. By use of timed color set and useful time attributes in tokens defined in CPN tools, timer and time-related problems of SIP are modeled and analyzed. Timer is an important part for SIP, especially the INVITE transaction.

RECONFIGURABLE PRODUCTION LINE MODELING AND SCHEDULING USING PETRI NETS AND GENETIC ALGORITHM

In response to the production capacity and functionality variations, a genetic algorithm （GA） embedded with deterministic timed Petri nets（DTPN） for reconfigurable production line（RPL） is proposed to solve its scheduling problem. The basic DTPN modules are presented to model the corresponding variable structures in RPL, and then the scheduling model of the whole RPL is constructed. And in the scheduling algorithm, firing sequences of the Petri nets model are used as chromosomes, thus the selection, crossover, and mutation operator do not deal with the elements in the problem space, but the elements of Petri nets model. Accordingly, all the algorithms for GA operations embedded with Petri nets model are proposed. Moreover, the new weighted single-objective optimization based on reconfiguration cost and E/T is used. The results of a DC motor RPL scheduling suggest that the presented DTPN-GA scheduling algorithm has a significant impact on RPL scheduling, and provide obvious improvements over the conventional scheduling method in practice that meets duedate, minimizes reconfiguration cost, and enhances cost effectivity.

Petri Nets—A Versatile Modeling Structure

Petri Nets (PNs) are an effective structure for modeling and analyzing asynchronous systems with concurrent and parallel activities. A Petri net models the static properties of a discrete event system concentrating on two basic concepts: events and conditions. Most of the theoretical work on Petri nets is a formal definition of Petri nets structures, which consist of a set of places, representing conditions, a set of transitions, representing events, an input function and an output function. For practical purposes, a graphical representation is more useful. Two types of nodes portray places and transitions. A circle is a place and a bar is a transition. There is no inherent measure of time in a classical Petri net. To approach time-based evaluation of system performances, Timed Petri Nets (TPNs) were introduced. Modeling the notion of time is not straightforward. There are several possibilities for introducing time in PNs, among them timed transitions and timed places. This paper reviews several published examples where Petri Nets were used in different circumstances such as estimating expected utilization of processing resources at steady state in open queueing networks, verifying computerized simulations and batch planning in textile industry.

Application Research of assembly line modeling based on Time Petri Net

With the continuous progress of manufacturing industry,automatic assembly line has become a very mature production mode in modern factories,and the quality of assembly line design has become an important issue related to the development of manufacturing enterprises.In this paper,a graphical model based on Petri Net is established for the first full load time of the assembly line.The accessibility of the P/T system and the production rhythm of the assembly line are calculated by computer simulation.Finally,according to the simulation model,an experimental platform is built to verify the rationality of the model.Experimental results show that the model can accurately express the equipment allocation process of assembly line.

Parametric Transformation of Timed Weighted Marked Graphs:Applications in Optimal Resource Allocation

Timed weighted marked graphs are a subclass of timed Petri nets that have wide applications in the control and performance analysis of flexible manufacturing systems.Due to the existence of multiplicities(i.e.,weights)on edges,the performance analysis and resource optimization of such graphs represent a challenging problem.In this paper,we develop an approach to transform a timed weighted marked graph whose initial marking is not given,into an equivalent parametric timed marked graph where the edges have unitary weights.In order to explore an optimal resource allocation policy for a system,an analytical method is developed for the resource optimization of timed weighted marked graphs by studying an equivalent net.Finally,we apply the proposed method to a flexible manufacturing system and compare the results with a previous heuristic approach.Simulation analysis shows that the developed approach is superior to the heuristic approach.

Modeling and Stability Analysis of a Communication Network System

In this work, the modeling and stability problem for a communication network system is addressed. The communication network system consists of a transmitter which sends messages to a receiver. The proposed model considers two possibilities. The first one, that messages are successfully received, while in the second one, during the sending process the transmitter breaks down and as a result the message does not reach the receiver. Timed Petrinets is the mathematical and graphical modeling technique utilized. Lyapunov stability theory provides the required tools needed to aboard the stability problem. Employing Lyapunov methods, a sufficient condition for stabilization is obtained. It is shown that it is possible to restrict the communication network system state space in such a way that boundedness is guaranteed. However, this restriction results to be vague. This inconvenience is overcome by considering a specific recurrence equation, in the max-plus algebra, which is assigned to the timed Petri net graphical model.

Model Predictive Control for Discrete and Continuous Timed Petri Nets

The goal of this paper is to propose a unique control method that permits the evolution of both timed continuous Petri net （TCPN） and T-timed discrete Petri net （T-TDPN） from an initial state to a desired one. Model predictive control （MPC） is a robust control scheme against perturbation and a consistent real-time constraints method. Hence, the proposed approach is studied using the MPC. However, the computational complexity may prevent the use of the MPC for large systems and for large prediction horizons. Then, the proposed approach provides some new techniques in order to reduce the high computational complexity; among them one is taking constant control actions during the prediction.

Using Timed Petri Net to Model Instruction-Level Loop Scheduling with Resource Constraints

This paper uses timed Petri net to model and analyze the problem of instructionlevel loop scheduling with resource constraints, which has been proven to be an NP complete problem. First, we present a new timed Petri net model to integrate functional unit allocation, register allocation and spilling ilno a unified theoretical framework.Then we develop a state subgraph, called Register Allocation Solution Graph, which can effectively describe the major behavior of our new model. The maill property of this state subgraph is that the number of all its nodes is polynomial. Finally we present and prove that the optimum loop schedules can be found with polynomial computation complexity, for almost all practical loop prograrns. Our work lightens a new idea of finding the optimum loop schedules.

A Multimedia Synchronization Model Based on Timed Petri Net

Multimedia synchronization is a significant requirement for distributed multimedia applications. In this paper, a multimedia synchronization model based on timed Petri nets is presented. Using this model one can give the abstraction and formal description for multimedia object compositions with time-constrained relations. Algorithms for asynchronous user interactions are also presented.

Modelling and analysis of hybrid stochastic timed Petri net

In this paper,an interesting Hybrid Stochastic Timed Petri Net(HSTPN)is proposed for a class of hybrid systems.The proposed HSTPN can be adopted to represent hybrid systems with discrete,continuous,conflicting,time-delay and stochastic characteristics simultaneously.The proposed HSTPN outperforms conventional hybrid Petri net models in terms of describing the scalability and immediacy of hybrid systems.Advantages of the HSTPN on describing hybrid system are verified by establishing some equivalent models of HPN and its derived models.

Solving Resource-constrained Multiple Project Scheduling Problem Using Timed Colored Petri Nets

To solve the resource-constrained multiple project scheduling problem(RCMPSP) more effectively,a method based on timed colored Petri net(TCPN) was proposed.In this methodology,firstly a novel mapping mechanism between traditional network diagram such as CPM(critical path method)/PERT(program evaluation and review technique) and TCPN was presented.Then a primary TCPN(PTCPN) for solving RCMPSP was modeled based on the proposed mapping mechanism.Meanwhile,the object PTCPN was used to simulate the multiple projects scheduling and to find the approximately optimal value of RCMPSP.Finally,the performance of the proposed approach for solving RCMPSP was validated by executing a mould manufacturing example.

Application of Timed Petri Nets to Analysis and Scheduling of Flexible Manufacturing Cells

In this paper, steady-state behaviors for a large class of flexible manufacturing cells are considered under two types of schedules, i.e., simple schedule and composite schedule. It is shown that each composite schedule can be obtained by composition of simple ones. A systematic approach to modeling and analysis of schedules is proposed cycle times of timed petri net models of schedules are derived. A example of three-machine cell is given.

Multi-agent based modeling for order distribution cooperative negotiation in supply chains

With the new characteristics of global cooperation in supply chains being synthetically considered,a hybrid model to the cooperative negotiation process for the order distribution in supply chain is mainly studied.After reviewing and analyzing some main domestic and overseas processes in cooperative negotiation modeling in supply chain,some problems are subsequently pointed out.For example,the traditional simple multi-agent system(MAS)frameworks which have some limitations,are not suitable for solving modeling complex systems.To solve these problems,thinking with the aid of the multi-agent structure and complex system modeling,the manufacturing supply chain is taken as an example,and a time Petri net production model is adopted to decompose the materials.And then a cooperative negotiation model for the order distribution in supply chain is constructed based on combining multi-agent techniques with time Petri net modeling.The simulation results reveal that the above model helps solve the problems of cooperative negotiation in supply chains.

Modeling and Analysis of Scheduling for Distributed Real-time Embedded Systems

Aimed at the deficiencies of resources based time Petri nets （RBTPN） in doing scheduling analysis for distributed real-time embedded systems, the assemblage condition of complex scheduling sequences is presented to easily compute scheduling length and simplify scheduling analysis. Based on this, a new hierarchical RBTPN model is proposed. The model introduces the definition of transition border set, and represents it as an abstract transition. The abstract transition possesses all resources of the set, and has the highest priority of each resource; the cxecution time of abstract transition is the longest time of all possible scheduling sequences. According to the characteristics and assemblage condition of RBTPN, the refinement conditions of transition border set are given, and the conditions ensure the correction of scheduling analysis. As a result, it is easy for us to understand the scheduling model and perform scheduling analysis.

Verifying Time Petri Nets by Linear Programming

The paper proposes an approach to solving some verification prob- lems of time Petri nets using linear programming. The approach is based on the observation that for loop-closed time Petri nets, it is only necessary to investigate a finite prefix of an untimed run of the underlying Petri net. Using the technique the paper gives solutions to reachability and bounded delay timing analysis problems. For both problems algorithms are given, that are decision procedures for loop-closed time Petri nets, and semi-decision procedures for general time Petri nets.

Soundness Analysis of Compositional Model of Time-Based Petri Nets

Workflow management systems are widely used in improving the efficiency of business processes. To develop a workflow management system is the key to workflow modeling. In this paper, the compositional time net is presented to model workflow processes on the basis of the analyzing methods of time Petri nets and workflows, and to describe the static relationships and the dynamic semantics of the task of multiple workflow com- position. The paper puts more emphasis on checking the sotmdness of composed workflow, at the same time, combinational problems of non-conditional structure of the compositional time net are introduced and analyzed. A sufficient and necessary condition for determining the soundness of compositional nets is obtained.