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International Symposium on Image and Data Fusion (ISIDF)

作者： Baida Zhang Yuhua Tang Junjie Wu Linqi Huang National laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology Changsha Hunan P. R. China School of Resources and Safety Engineering Central South University Changsha P. R. China

Graph isomorphism problem has applications in many fields, such as chemistry, computer science, electronics, and network theory. But the exponential complexity of the algorithm makes the testing is time consuming. In this paper, a new algorithm named Unique Vertex Delete (UVD for short) is presented to speed up the process of isomorphic testing. The main idea of UVD algorithm is deleting vertex continuously to reduce the scale of the problem, and new field is added for each vertex to indicate the information of deleted neighbor vertices. Theoretical analysis and experiments show that the UVD algorithm consistently and significantly outperforms existing state-of-the-art approaches.

关键词： Algorithm design and analysis Testing Educational institutions Polynomials Software algorithms Complexity theory Partitioning algorithms

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An effective control scheme to ensure real-time causal order in large-scale distributed interactive simulations

An effective control scheme to ensure real-time causal order...

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International Conference on Communication Software and Networks, ICCSN

作者： Hangjun Zhou Sha Fu Key Laboratory of Science and Technology for National Defence of Parallel and Distributed Processing School of Computer Science National University of Defense Technology Changsha Hunan China Department of Information Management Hunan University of Finance and Economics Changsha Hunan China

When a large-scale distributed interactive simulation system is running on WAN, the sites usually disperse over a wide area in geography, which results in the simulation clock of each site is hardly to be accurately synchronized with that of other sites. The asynchronous clocks and large transmission latency on WAN bring on a problem for the large-scale simulations to preserve the real-time causal order delivery of received events at each site. In this article, we analyze the indirect way to compare the values of asynchronous simulation clocks at first, and then propose a novel scheme which can select the reconstructible causal control information for each message so as to ensure the causal ordering of events in real time. Experiments demonstrate that the scheme can weaken the effect of network latency, reduce the overhead of the transmission amount of control information and improve the causal order consistency in asynchronous distributed simulations.

关键词： Clocks Educational institutions

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A causality based dynamic message ordering for DVEs on Wide Area Network

A causality based dynamic message ordering for DVEs on Wide ...

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International Conference on Communication Software and Networks, ICCSN

Due to the large message transmission latency in distributed Virtual Environments(DVEs) on Wide Area Net-work(WAN), the effectiveness of causality consistency control of message ordering is determined by not only causal order of messages but also the real-timeness. If merely causal order is considered, the real-time property of DVEs may not be ensured because of the unlimited waiting time for the delayed messages. While if only real-timeness is emphasized, there may be too many delayed messages, which have to be discarded, to maintain the quality of causal message ordering. Therefore, a trade-off between the quality of causal order delivery and real-timeness is necessary for DVEs. In this article, a novel causality based message ordering approach is presented. In general, this new approach dynamically balances the demands of causal order delivery and real-timeness. Experiment results demonstrate the approach can enhance the quality of causality, while simultaneously keep the real-time property of DVEs.

关键词： Educational institutions

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Fine-grained location-free planarization in wireless sensor networks

Fine-grained location-free planarization in wireless sensor ...

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IEEE Annual Joint Conference: INFOCOM, IEEE computer and Communications Societies

作者： Dezun Dong Yunhao Liu Xiangke Liao Xiang-Yang Li National Laboratory for Paralleling and Distributed Processing School of Computer National University of Defense Technology Changsha China CSE Department HKUST China TNLIST School of Software Tsinghua University China

ISBN: (纸本)9781424499199

Extracting planar graph from network topologies is of great importance for efficient protocol design in wireless ad hoc and sensor networks. Previous techniques of planar topology extraction are often based on ideal assumptions, such as UDG communication model and accurate node location measurements. To make these protocols work effectively in practice, we need extract a planar topology in a location-free and distributed manner with small stretch factor. Current location-free methods cannot provide any guarantee on the stretch factor of the constructed planar topologies. In this work, we present a fine-grained and location-free network planarization method. Compared with existing location-free planarization approaches, our method can extract a high-quality planar graph, called TPS (Topological Planar Simplification), from the communication graph using local connectivity information. TPS is proved to be a planar graph and has a constant stretch factor for a large class of network instances. We evaluate our design through extensive simulations and compare with the state-of-the-art approaches. The simulation results show that our method produces planar graphs with a small constant stretch factor, often less than 1.5.

关键词： Tiles Planarization Network topology Topology Protocols Ad hoc networks Routing

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A review on the churn character of P2P networks

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Jisuanji Xuebao/Chinese Journal of computers 2011年第9期34卷 1563-1577页

作者： Fu, Zhi-Peng Wang, Huai-Min Shi, Dian-Xi Zou, Peng School of Computer Science National University of Defense Technology Changsha 410073 China National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha 410073 China

P2P application is one of the most popular applications in the Internet, but its performance is badly influenced by the churn character-the nodes continuous arrival and departure. On the basis of introducing the origin of the churn, the definition of it and its influences to the P2P system performance, we minutely describe the research on the statistical properties, and discover some dynamic law including nodes' session time generally obey the heavy-tailed distribution. Then we detail the measurement methods. For passive monitoring, active monitoring, sample and so on, we present the advantages and disadvantages of each method, and explain the corresponding improving method to enhance the accuracy of the measurement. After that we elaborate the resilience strategies to the churn. Towards the neighbor selection, failure recovery, replica maintenance, link lifetime maintenance and so on, we present also the advantage and disadvantage of each strategy, and present our view to each of aspects. Finally, the summary and prospect of the future research are given.

关键词： Peer to peer networks

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A multi-layered emulation platform to verify the effectiveness of consistency control approaches about message ordering

A multi-layered emulation platform to verify the effectivene...

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International Conference on Communication Software and Networks, ICCSN

作者： Hangjun Zhou Sha Fu Key Laboratory of Science and Technology for National Defence of Parallel and Distributed P rocessing School of Computer Science National University of Defense Technology Changsha Hunan China Department of Information Management Hunan University of Finance and Economics Changsha Hunan China

It is an important issue to preserve the consistent delivering order of messages at each site in distributed Virtual Environments(DVEs). Currently, the violations of message delivery order are inclined to happen in the large-scale and frequently interactive DVEs running on Wide Area Network(WAN). The inconsistent anomalies are characterized as unpredictable, unrepeatable and uncontrollable, which results in the severe problem for the development of the consistency control approaches. Meanwhile, it is also highly expensive to directly verify the proposed approaches on WAN. Therefore, in this paper, we design and establish an original multi-layered emulation platform in LAN, which can emulate the network latency of WAN and repeat the scenarios of violations. On the platform, the designers of consistency approaches don't have to spend efforts to realize the fundamental functions of the verification, but could pay more attention to the development and optimization of the control algorithms, which is very beneficial for the improvement of message ordering approaches.

关键词： Switches Wide area networks

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Accelerating MatLab code using GPU: A review of tools and strategies

Accelerating MatLab code using GPU: A review of tools and st...

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International Conference on Artificial Intelligence, Management Science and Electronic Commerce (AIMSEC)

作者： Baida Zhang Shuai Xu Feng Zhang Yuan Bi Linqi Huang National laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology Changsha China Department of Information Engineering Academy of Armored Forces Engineering Beijing China Inspur (Beijing) Electronic Information Industry Company Limited Beijing China Naval Academy of Armament Beijing China School of Resources and Safety Engineering Central South University Changsha China

Lots of toolboxes of accelerating MatLab using GPU are available now[1], but, users are confused by which toolbox is best suitable for a particular task. Three toolboxes-Jacket, GPUmat, and parallel Computing Toolbox of MatLab are selected. For each toolbox, its advantages and pitfalls are reviewed, with an aim to allow the reader to identify which toolbox is appropriate for a given task. Strategies of whether a function should execute on GPU are given after a formula analysis. The analysis is also a framework for program automatically decides which function is cost-efficient to execute on GPU. A series of benchmark of different types of computing, including data transfer between GPU and CPU, data matrix Generation, matrix operation and GPU functions were tested in all three toolboxes. And the results show that Jacket is the best one. Some advices to improve the performance of toolboxes are given in the end.

关键词： Graphics processing unit Acceleration parallel processing computer architecture Conferences Licenses MATLAB

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Dynamic program Behavior Identification for high performance CMPs with private LLCs

Dynamic program Behavior Identification for high performance...

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作者： Jia, Xiaomin Lu, Pingjing Sun, Caixia Zhang, Minxuan National Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology China

Chip Multi-Processors (CMPs) emerge as a mainstream architectural design alternative for high performance parallel and distributed computing. Last Level Cache (LLC) management is critical to CMPs because off-chip accesses often require a long latency. Due to its short access latency, well performance isolation and easy scalability, private cache is an attractive design alternative for LLC of CMPs. This paper proposes program Behavior Identification-based Cache Sharing (BICS) for LLC management. BICS is based on a private cache organization for the shorter access latency. Meanwhile, BICS tries to simulate a shared cache organization by allowing evicted blocks of one private LLC to be saved at peer LLCs. This technique is called spilling. BICS identifies cache behavior types of applications at runtime. When a cache block is evicted from a private LLC, cache behavior characteristics of the local application are evaluated so as to determine whether the block is to be spilled. Spilled blocks are allowed to replace some valid blocks of the peer LLCs as long as the interference is within a reasonable level. Experimental results using a full system CMP simulator show that BICS improves the overall throughput by as much as 14.5%, 12.6%, 11.0% and 11.7% (on average 8.8%, 4.8%, 4.0% and 6.8%) over private cache, shared cache, Utility-based Cache Partitioning (UCP) scheme and the baseline spilling-based organization Cooperative Caching (CC) respectively on a 4-core CMP for SPEC CPU2006 benchmarks. Copyright© 2010.

关键词： Integrated circuit design

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Evaluating the performance and accuracy impact of trace generation to the bigsim emulator

Evaluating the performance and accuracy impact of trace gene...

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10th IEEE International Conference on computer and Information Technology, CIT-2010, 7th IEEE International Conference on Embedded Software and Systems, ICESS-2010, 10th IEEE Int. Conf. Scalable Computing and Communications, ScalCom-2010

作者： Che, Yonggang Xu, Chuanfu Lu, Pingjing National Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology Changsha China

ISBN: (纸本)9780769541082

This paper quantitatively studies the trace effects to the performance and accuracy of the BigSim Emulator, a scalable parallel emulator for large-scale computers. To assess the accuracy effect we modify the emulator code to collect the predicted computation time. Four MPI programs with different computation to communication ratios are used as benchmarks. The emulation time and the predicted computation time, both when trace generation are enabled and disabled, are collected on two parallel host machines. The results show that although the BigSim Emulator only traces communication events and dependencies, trace generation still evidently degrades the emulation performance for programs with high communication to computation ratios. Trace generation also significantly affects the accuracy of the predicted computation time for communication intensive programs, which is an issue that can not be overlooked. © 2010 IEEE.

关键词： BigSim emulator MPI programs digital simulation emulator code large scale computers message passing parallel host machines parallel programming performance evaluation scalable parallel emulator trace generation accuracy impact

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Feature preserving consolidation for unorganized point clouds

Feature preserving consolidation for unorganized point cloud...

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IEEE International Conference on Progress in Informatics and Computing (PIC)

作者： Li, Bao Jiang, Wei Cheng, Zhiquan Dang, Gang Jin, Shiyao National Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology Changsha China

ISBN: (纸本)9781424467860

We introduce a novel method for the consolidation of unorganized point clouds with noise, outliers, non-uniformities as well as sharp features. This method is feature preserving, in the sense that given an initial estimation of normal, it is able to recover the sharp features contained in the original geometric data which are usually contaminated during the acquisition. The key ingredient of our approach is a weighting term from normal space as an effective complement to the recently proposed consolidation techniques. Moreover, a normal mollification step is employed during the consolidation to get normal information respecting sharp features besides the position of each point. Experiments on both synthetic and real-world scanned models validate the ability of our approach in producing denoised, evenly distributed and feature preserving point clouds, which are preferred by most surface reconstruction methods. ©2010 IEEE.

关键词： Consolidation Feature preserving Point clouds Sharp features

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