the traditional technique to simulate physical systems modeled by partial differential equations is by means of a time-stepped methodology where the state of the system is updated at regular discrete time intervals. T...
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ISBN:
(纸本)3540290672
the traditional technique to simulate physical systems modeled by partial differential equations is by means of a time-stepped methodology where the state of the system is updated at regular discrete time intervals. this method has inherent inefficiencies. Recently, we proposed [1] a new asynchronous formulation based on a discrete-event-driven (as opposed to time-driven) approach.. where the state of the simulation is updated on a '' need-to-be-done-only '' basis. Using a serial electrostatic implementation, we obtained more than two orders of magnitude speedup compared with traditional techniques. Here we examine issues related to the parallel extension of this technique and discuss several different parallel strategies. In particular, we present in some detail a newly developed discrete-event based parallel electromagnetic hybrid code and its performance using conservative synchronization on a cluster computer. these initial performance results are encouraging in that they demonstrate very good parallel speedup for large-scale simulation computations containing tens of thousands of cells, though overheads for inter-processor communication remain a challenge for smaller computations.
the proceedings contain 65 papers. the topics discussed include: decision table based analysis of trading models;a three-layer model for software engineering metrics;design phase analysis of software qualities using a...
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ISBN:
(纸本)076952611X
the proceedings contain 65 papers. the topics discussed include: decision table based analysis of trading models;a three-layer model for software engineering metrics;design phase analysis of software qualities using aspect-oriented programming;applying dynamic change impact analysis in component-based architecture design;transforming linear terms of algebraic specifications into extended pomsets;an extension of robustness slicing algorithm based on dynamic array;text classification by combining different distance functions with weights;network intrusion detection through genetic feature selection;minimizing multicast communication latency in WAN-based environment;a software tool for network traffic analysis;topology control and mobility management in mobile Ad Hoc Networks;approximation algorithm for maximum lifetime in wireless sensor networks with data aggregation;and a survey of software estimation techniques and project planning practices.
Internet worm attacks have become increasingly more frequent and have caused enormous damage to the Internet community during the past years. A new security service that monitors the ongoing worm activities on the Int...
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ISBN:
(纸本)9780769527369
Internet worm attacks have become increasingly more frequent and have caused enormous damage to the Internet community during the past years. A new security service that monitors the ongoing worm activities on the Internet and restricts the worm spreading rate automatically will greatly contribute to the security management of modern enterprise networks. Based on the comparison and analysis of many worm detection and containment strategies, a new and effective algorithm of detecting and containing network worms is proposed in this paper. the principle of this effective algorithm is an improved two rotation process to detect and contain worms. the simulation result of the algorithm is demonstrated so effectively to detect and slow down the rapid scanning worm and "stealthy" worm whose propagation rate is slower than the former. In order to reduce the number of false positives, the impact of normal network activities is also concerned Finally, the simulation also analyzes the performance of detecting worms of the algorithm under normal and congestive network background.
Popular network simulation tools, such as ns-2, are useful for undertaking experiments with emerging networking technologies. As net-worked applications become distributed at scales comparable to the Internet, such as...
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ISBN:
(纸本)1424400007
Popular network simulation tools, such as ns-2, are useful for undertaking experiments with emerging networking technologies. As net-worked applications become distributed at scales comparable to the Internet, such as peer-to-peer applications, testing and experimentation becomes increasingly difficult and important Withthis paper, we are introducing an elaborate extension to existing simulation capabilities by allowing realistic highly distributed application prototypes to be attached to a simulator for transparent testing and experimentation. We enable developers to focus on building their applications rather than detailing simulation scripts. Testing can then be performed in a natural setting. PDNS is a parallel and distributed version of the commonly used ns-2 simulation package. We describe our extensions to the PDNS simulator which allow real application prototypes to be run across a simulated network. We describe our use of virtualisation as a means for sending an application's network traffic through the simulator. Our implementation allows for large scale simulations withthousands of real peers and hundereds of thousands of simulated nodes in a network, thus we can test real peer-to-peer software at large scales.
Many algorithms have been proposed in literature for digital film restoration;unfortunately, none of them ensures a perfect restoration whichever is the image sequence to be restored. Here, we adopt an approach to dig...
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ISBN:
(纸本)0769522556
Many algorithms have been proposed in literature for digital film restoration;unfortunately, none of them ensures a perfect restoration whichever is the image sequence to be restored. Here, we adopt an approach to digital scratch restoration based on the combination of relatively well settled distinct techniques. We propose P-LSR, a parallel version focusing on strategies based on both task and data partitioning to achieve good load balancing, that well adapts also to be distributed. parallel performance is deeply investigated for several real image sequences.
the proceedings contain 18 papers. the topics discussed include: use case maps as an aid in the construction of a formal specification;test cases generation for nondeterministic duration systems;a Petri net based appr...
ISBN:
(纸本)9789898111906
the proceedings contain 18 papers. the topics discussed include: use case maps as an aid in the construction of a formal specification;test cases generation for nondeterministic duration systems;a Petri net based approach for modeling and analyzing interorganizational workflows with dynamic structure;modeling the system organization of multi-agent systems in early design stages with coarse design diagrams;a process-oriented tool-platform for distributed development;preliminary design of an agent-based system for human collaboration in chemical incidents response;from reactive to deliberative multi-agent planning;layered queuing networks for simulating enterprise resource planning systems;the role of testing in agile and conventional methodologies;multi project organization optimization using genetic algorithm;and making use case slices manage variability in aspect-based product line.
In this paper, a new event scheduling mechanism XEQ and a new rollback procedure rb-messages are proposed for use in optimistic logic simulation. We incorporate both of these techniques in a simulator XTW. XTW groups ...
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ISBN:
(纸本)0769523838
In this paper, a new event scheduling mechanism XEQ and a new rollback procedure rb-messages are proposed for use in optimistic logic simulation. We incorporate both of these techniques in a simulator XTW. XTW groups LPs into clusters, and makes use of a multi-level queue,XEQ, to schedule events in the cluster. XEQ has an O(1) event scheduling time complexity. Our new rollback mechanism replaces the use of anti-messages by an rb-message, and eliminates the need for an output queue at each LP. Experimental comparisons to Time Warp reveal a superior performance on the part of XTW, while experimental results over large circuits (5-million-gate to 25-million-gate) shows XTW scales well with boththe size of circuits and the number of processors.
Cluster analysis is a valuable tool for exploratory pattern analysis, especially when very little a priory knowledge about the data is available. distributed systems, based on high speed intra-net connections, provide...
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ISBN:
(纸本)0769522556
Cluster analysis is a valuable tool for exploratory pattern analysis, especially when very little a priory knowledge about the data is available. distributed systems, based on high speed intra-net connections, provide new tools in order to design new and faster clustering algorithms. Here, a parallel genetic algorithm for clustering called PGAC is described. the used strategy of parallelization is the island model paradigm where different populations of chromosomes (called demes) evolve locally to each processor and from time to time some individuals are moved from one deme to another. Experiments have been performed for testing the benefits of the parallelisation paradigm in terms of computation time and correctness of the solution.
this paper discusses the NP-complete multi-constrained path problem with imprecise state information, and a distributed heuristic framework without any imprecision assumption is presented. this framework needs no link...
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ISBN:
(纸本)8955191235
this paper discusses the NP-complete multi-constrained path problem with imprecise state information, and a distributed heuristic framework without any imprecision assumption is presented. this framework needs no link state exchanging message, and employs mobile agents to search feasible paths in parallel. Two key strategies, the one to select a suitable next node and the other to choose the appropriate one from all feasible paths, are used. simulation results indicate that the presented solution is scaleable and efficient. An appropriate path selecting strategy with traffic engineering can improve network performance. And the framework can tolerate high degree of information imprecision.
this contribution approaches the problem of scratch restoration in old movies as a optimisation's problem. the functional based on the statistical properties of the image around the scratch is optimised using an a...
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ISBN:
(纸本)0769522556
this contribution approaches the problem of scratch restoration in old movies as a optimisation's problem. the functional based on the statistical properties of the image around the scratch is optimised using an ad-hoc genetic algorithm. Given the large amount of the computational time needed by genetic algorithms, a network of standard workstations with heterogeneous operating systems has been used. Each workstation in the network works on each scratch to perform the restoration, and a specific machine works as root node withthe task of distributing jobs on the network and adding the outputted restored scratches back into the image.
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