In this paper, a new analytic method for modeling and evaluating mobile ad hoc networks (MANET) is proposed. Petri nets technique is introduced into MANET and a packet-flow parallel scheduling scheme is presented usin...In this paper, a new analytic method for modeling and evaluating mobile ad hoc networks (MANET) is proposed. Petri nets technique is introduced into MANET and a packet-flow parallel scheduling scheme is presented using Stochastic Petri Nets (SPN). The flowing of tokens is used in graphics mode to characterize dynamical features of sharing a single wireless channel. Through SPN reachability analysis and isomorphic continuous time Markov process equations, some network parameters, such as channel efficiency, one-hop transmission delay etc., can be obtained. Compared with conventional performance evaluation methods, the above parameters are mathematical expressions instead of test results from a simulator.展开更多
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 n...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.展开更多
Fuzzy technology is a newly developed discipline based on fuzzy mathematics. In the recent years, it has been successfully applied into many areas, such as process control, diagnosis, evaluation, decision making and s...Fuzzy technology is a newly developed discipline based on fuzzy mathematics. In the recent years, it has been successfully applied into many areas, such as process control, diagnosis, evaluation, decision making and scheduling, especially in simulation where accurate mathematical models can not or very hard be established. In this paper, to meet the demands of fuzzy simulation, two fuzzy nets will first be presented, which are quite suitable for modeling the parallel or concurrent systems with fuzzy behavior. Then, a concept of active simulation will be introduced, in which the simulation model not only can show its fuzzy behavior, but also has a certain ability which can actively perform many very useful actions, such as automatic warning, realtime monitoring, simulation result checking, simulation model self-adapting, error recovery, simulating path tracing, system states inspecting and exception handling, by a unified approach while some specified events occur. The simulation model described by this powerful simulation modeling tool is concurrently driven by a network interpreter and an event monitor that all can be implemented by software or hardware. Besides, some interesting applications are given in the paper.展开更多
为解决多工艺路线下的柔性加工系统(Flexible Machining System under Alternative Routes,FMSAR)中加工和运输工序集成调度困难、生产效率低下的问题,以完工时间为目标,考虑工件加工、工件运输、工件批量和多工艺路线的情况,建立了柔...为解决多工艺路线下的柔性加工系统(Flexible Machining System under Alternative Routes,FMSAR)中加工和运输工序集成调度困难、生产效率低下的问题,以完工时间为目标,考虑工件加工、工件运输、工件批量和多工艺路线的情况,建立了柔性加工系统赋时变迁Petri网模型,该建模方法避免了工件共享资源造成的死锁情况。在此基础上,以可行变迁序列为输入,设计了实际代价函数和启发式预估代价函数,并结合波束搜索框架,只对每个搜索阶段的部分优秀节点进行下一步拓展,减小了可达图搜索空间,提高了算法运行效率。通过实例分析和算法对比,验证了该建模方法的可靠性和优化方法的可行性。展开更多
文摘In this paper, a new analytic method for modeling and evaluating mobile ad hoc networks (MANET) is proposed. Petri nets technique is introduced into MANET and a packet-flow parallel scheduling scheme is presented using Stochastic Petri Nets (SPN). The flowing of tokens is used in graphics mode to characterize dynamical features of sharing a single wireless channel. Through SPN reachability analysis and isomorphic continuous time Markov process equations, some network parameters, such as channel efficiency, one-hop transmission delay etc., can be obtained. Compared with conventional performance evaluation methods, the above parameters are mathematical expressions instead of test results from a simulator.
文摘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.
文摘Fuzzy technology is a newly developed discipline based on fuzzy mathematics. In the recent years, it has been successfully applied into many areas, such as process control, diagnosis, evaluation, decision making and scheduling, especially in simulation where accurate mathematical models can not or very hard be established. In this paper, to meet the demands of fuzzy simulation, two fuzzy nets will first be presented, which are quite suitable for modeling the parallel or concurrent systems with fuzzy behavior. Then, a concept of active simulation will be introduced, in which the simulation model not only can show its fuzzy behavior, but also has a certain ability which can actively perform many very useful actions, such as automatic warning, realtime monitoring, simulation result checking, simulation model self-adapting, error recovery, simulating path tracing, system states inspecting and exception handling, by a unified approach while some specified events occur. The simulation model described by this powerful simulation modeling tool is concurrently driven by a network interpreter and an event monitor that all can be implemented by software or hardware. Besides, some interesting applications are given in the paper.
文摘为解决多工艺路线下的柔性加工系统(Flexible Machining System under Alternative Routes,FMSAR)中加工和运输工序集成调度困难、生产效率低下的问题,以完工时间为目标,考虑工件加工、工件运输、工件批量和多工艺路线的情况,建立了柔性加工系统赋时变迁Petri网模型,该建模方法避免了工件共享资源造成的死锁情况。在此基础上,以可行变迁序列为输入,设计了实际代价函数和启发式预估代价函数,并结合波束搜索框架,只对每个搜索阶段的部分优秀节点进行下一步拓展,减小了可达图搜索空间,提高了算法运行效率。通过实例分析和算法对比,验证了该建模方法的可靠性和优化方法的可行性。
