共查询到20条相似文献,搜索用时 140 毫秒
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随着现代战争中高技术武器装备大量涌现,各类军事电子信息系统仿真的规模不断扩大、内容不断更新,传统的软件开发方法虽然能够满足基于HLA仿真的实时要求,但已经不能满足系统复杂程度和开发效率的需要.因此,采用UML开发方法,利用I-logix公司的Rhapsody工具,以基于HLA分布式仿真的剧情联邦成员开发为例,建立了剧情联邦成员软件体系结构,并给出了基于HLA分布式剧情仿真的联邦成员的建模方法,结果表明,此方法满足HLA分布式仿真的时间推进实时要求,增强了建模的直观性和易理解性,提高了软件开发效率,并使剧情联邦成员软件开发具有可靠性高、模型重用性好、易于扩充和开发周期短等优点. 相似文献
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基于HLA的卫星通信链路分布式仿真的研究 总被引:1,自引:0,他引:1
该文首先对HLA进行了概述。其次介绍了卫星通信链路仿真系统的功能,该功能是由10个模型构成的基础模块和应用模块实现的;在此基础上提出了一种基于HLA的卫星通信链路分布式仿真系统的设计框架,构建了由11个联邦成员组成的卫星通信链路仿真联邦,并较为详细地阐述了仿真系统的联邦成员的设计和联邦成员间信息交互的设计,给出了联邦成员间信息传递关系的示意图,较好地解决了仿真系统各功能模型的同步、并行运行的问题;最后通过仿真得出了有关结论,为卫星通信链路、通信网络的设计与性能评估奠定了基础。 相似文献
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基于HLA的仿真应用系统开发中的时间同步研究 总被引:2,自引:0,他引:2
确保仿真节点间数据的正确传输和时间同步是分布式仿真系统设计的关键。该文从应用层角度出发,分析了基于HLA/RTI仿真系统设计中的时间管理机制,研究了联邦成员间数据的交互原理。采用对比时戳的方法解决了在仿真应用系统开发中联邦成员对所接收消息进行确认而得到所需数据的问题,对成员在时间管理中存在的其它问题也采取相应的措施进行了处理,从而保证整个联邦同步运行该文对于RTI系统的开发能起到一定的互动效果。 相似文献
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基于HLA的仿真程序设计研究 总被引:4,自引:2,他引:4
高层体系结构HLA以其突出的互操作性和可重用性,成为当今分布式交互仿真系统结构标准,研究基于HLA的仿真程序设计方法对于分布式交互仿真系统的开发具有重要意义。该文从联邦创建到联邦退出,以程序设汁的角度,详细地剖析了联邦执行的整个生命周期过程,还分析了联邦执行的整个生命周期中联邦执行的各种状态以及联邦成员、联邦执行、RTI这三者之间的关系。根据联邦执行的生命周期过程,给出了联邦成员的应用程序框架,并且举例说明了HLA仿真程序设计的步骤和一般方法。 相似文献
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提出在高层体系结构(HLA)下集成多Agent的方法对半导体生产线进行建模与仿真。多Agent系统可以提供仿真的智能支持,而HLA则可以提供一致的基础框架,解决多Agent仿真带来的互操作和一致性问题。针对半导体生产调度的特点,构建了仿真系统框架。仿真联邦由Agent联邦成员和非Agent联邦成员组成,各联邦成员之间通过对象类、交互类、Agent消息实现互相访问,Agent联邦成员通过协商算法生成优化的调度方案。最后,基于JADE实现了一个多Agent的半导体生产线调度仿真系统,并进行了仿真实验。 相似文献
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时空一致性是分布交互式仿真的关键问题,联网仿真的计算机之间的的时间同步必须达到一定的精度,而计算机的时钟分辨率是制约仿真系统时间同步精度的重要因素。在Windnws2000/NT操作系统下PC机系统时钟的分辨率较低,且时间漂移率较高,因此在使用PC机和Windows2000/NT操作系统的分布交互式仿真系统中,如果使用系统时钟,时间同步精度不可能很高,如果为每台PC机加装高性能外部时钟的话,不但会增加系统成本,而且也不利于系统扩展。该文提出了一种基于PC机性能计数器的高分辨率、低时间漂移时钟的设计方案,解决了分布交互式仿真系统基于PC机自身资源获取高性能时钟的问题。 相似文献
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Integrating External and Internal Clock Synchronization 总被引:2,自引:1,他引:1
We address the problem of how to integrate fault-tolerant external and internal clock synchronization. In this paper we propose a new external/internal clock synchronization algorithm which provides both external and internal clock synchronization for as long as a majority of the reference time servers (servers with access to reference time) stay correct. When half or more of the reference time servers are faulty, the algorithm degrades to a fault-tolerant internal clock synchronization algorithm. We prove that at least 2 F+1 reference time servers are necessary for achieving external clock synchronization when up to F reference time servers can suffer arbitrary failures, thus the proposed algorithm provides maximum fault-tolerance. In this paper we also derive lower bounds for the best maximum external deviation achievable in standard mode and the best drift rate achievable in degraded mode. Our algorithm is optimal with respect to these two bounds: (1) the maximum external deviation is optimal in standard mode, and (2) the drift rate of the clocks is optimal in standard and degraded mode. 相似文献
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A clock synchronization service ensures that spatially dispersed and heterogeneous processors in a distributed system share a common notion of time. In order to behave as a single, unified computing resource, distributed systems have need for a fault-tolerant, clock synchronization service. One approach employs the interactive convergence (ICV) method, which is both fully distributed and inherently fault-tolerant. However, this approach suffers from limits in terms of system scalability due to resource overhead. In this paper, a new layered form of ICV is introduced, compared with basic ICV and other simpler alternatives via experimental analysis on a distributed system testbed, and shown to improve synchronization tightness, resource utilization, and scalability. 相似文献
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Due to the ability of sensor nodes to collaborate, time synchronization is essential for many sensor network operations. With the aid of hardware capabilities, this work presents a novel time synchronization method, which employs a dual-clock delayed-message approach, for energy-constrained wireless sensor networks (WSNs). To conserve WSN energy, this study adopts the flooding time synchronization scheme based on one-way timing messages. Via the proposed approach, the maximum-likelihood (ML) estimation of time parameters, such as clock skew and clock offset, can be obtained for time synchronization. Additionally, with the proposed scheme, the clock skew and offset estimation problem will be transformed into a problem independent of random delay and propagation delay. The ML estimation of link propagation delay, which can be used for localization systems in the proposed scenario, is also obtained. In addition to good performance, the proposed method has low complexity. 相似文献
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This paper presents an innovative method to synchronize physical clocks for a computational grid, in particular for a computational grid linked through the asynchronous In-tranet or Internet environments. The method discussed is an asynchronous self-adaptive clock synchronization mechanism. Two strategies for clock synchronisation are introduced. (1) Use con-tinuous time intervals to calculate the precision of clocks, which can reduce the effect of network delay effciently. (2) Every node synchronizes its clock with its leader actively. In addition, a node self-adaptive model is presented, and the relationship between the clock precision and synchroniza-tion time is induced, hence a node can predict when it should begin the synchronization process.Detailed simulation and extension of this issue are provided at the end of the paper. The presented model is both practical and feasible. 相似文献
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In distributed simulation, there is no uniform physical clock. And delay cannot be estimated because of jitter. So simulation time synchronization is essential for the event consistency among nodes. This paper investigates time synchronization algorithms over large-scale distributed nodes, analyzes LBTS (lower bound time stamp) computation model described in IEEE HLA standard, and then presents a grouped LBTS model. In fact, there is a default premise for existing algorithms that controi packets must be delivered via reliable transportation. Although, a theorem of time synchronization message's reliability is proposed, which proves that only those control messages that constrain time advance need reliability. It breaks out the default premise for reliability. Then multicast is introduced into the transmis- sion of control messages, and algorithm MCTS (multi-node coordination time synchronization) is proposed based on multicast. MCTS not only promotes the time advance efficiency, but also reduces the occupied network bandwidth. Experiment results demonstrate that the algorithm is better than others in both time advance speed and occupied network bandwidth. Its time advance speed is about 50 times per second when there are 1000 nodes, approximately equal to that of similar systems when there are 100 nodes. 相似文献
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时钟同步技术是分布式系统中非常活跃的研究领域之一,由于大多数分布式系统实际上是不同步的,因此需要采用容错时钟同步算法确保消息通信的有界延迟,而基于假设检验的时钟同步技术可以避免因错失对两个高概率不同步时钟进行同步调整而造成系统不正常使用的情况。该文讨论了时钟同步的假设检验问题。除了假设检验、两类错误概率,还给出了概率最小时钟偏差、时钟同步概率等概念。在时钟偏差的统计分布特性近似于服务正态分布的假设条件之下,提出了基于非中心t分布的时钟同步假设检验方案。最后,基于服务器和客户端之间双向消息通信传输模式,给出时钟偏差的估计和检验样本。 相似文献
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de Azevedo M.M. Blough D.M. 《Parallel and Distributed Systems, IEEE Transactions on》1998,9(12):1195-1212
We present a new approach for fault-tolerant internal clock synchronization in multicomputer systems employing not completely connected networks (NCCNs). The approach is referred to as multistep interactive convergence and is locally implemented in each multicomputer node by a time server process (TSP). We describe a specific algorithm that uses multistep interactive convergence and bases its operation on a logical mapping of the system's TSPs into an m-dimensional array. A TSP executes m steps per round of synchronization, with each step including a call to an interactive convergence procedure. For any TSP, clock readings in step i are gathered only from TSPs with which it shares a row along dimension i of the array. Hence, a TSP reads clocks only from a small subset of the TSPs in the system, which reduces the number of messages by orders of magnitude over a conventional interactive convergence algorithm in which reliable all-to-all broadcast of clock values is done. The algorithm can be used in systems of arbitrary topology and provides the added benefit of increased locality of communication in regular NCCNs such as hypercubes and tori. These advantages can be combined with a variety of message staggering mechanisms to maintain network contention at a minimum. We present expressions for the maximum clock skew, maximum clock drift, maximum clock discontinuity, and number of messages produced by the algorithm, and show that it tolerates arbitrary faults. A comparison with other algorithms that elucidates the advantages of multistep interactive convergence is also provided 相似文献