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A review on the churn character of P2P networks

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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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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SemanticCast: Content-based data distribution over self-organizing semantic overlay networks

SemanticCast: Content-based data distribution over self-orga...

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11th International Conference on parallel and distributed Computing, Applications and Technologies, PDCAT 2010

作者： Zheng, Zhong Wang, Yijie National Key Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology Changsha China

ISBN: (纸本)9780769542874

Many applications demand distributing data with different contents efficiently in the network environment with unreliable links and a high node churn. Existing approaches mostly focus on optimizing either efficiency or robustness of data distribution, and fail to ensure both of them simultaneously. In this paper, we propose SemanticCast - a content-based data distribution approach over self-organizing semantic overlay networks. SemanticCast maintains a self-organizing semantic overlay based on view exchange (called Crowd). In Crowd, each node seeks neighbors with more similar interests by periodically exchanging its neighbor list (called view) with a chosen neighbor. Through these nodes' self-organizing behavior, various interest communities emerge in the overlay. For data distribution over Crowd, SemanticCast adopts random walk to route data between interest communities, and adopts flooding to disseminate data inside the interested communities. The experimental results show that compared to existing approaches, SemanticCast can support efficient content-based data distribution in the unreliable and highly dynamic network environment. © 2010 IEEE.

关键词： Semantics

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CANSE: A churn adaptive approach to network size estimation

CANSE: A churn adaptive approach to network size estimation

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16th IEEE International Conference on parallel and distributed Systems, ICPADS 2010

作者： Ma, Xing-Kong Wang, Yi-Jie Zheng, Zhong National Key Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology Changsha China

ISBN: (纸本)9780769543079

Network size is one of the fundamental information of distributed applications. The approach to estimate network size must feature both high accuracy and robustness in order to adapt to the dynamic environment in different topologies. However, existing approaches fail to guarantee accuracy and robustness simultaneously in dynamic topologies due to the randomness of nodes sampled. In this paper, we propose a churn adaptive approach to network size estimation - CANSE, which collects closest nodes in identification to each node's identification by sampling nodes periodically. Each node collects closest identifications by two schemes. One scheme is sampling random nodes from random walks along the topology. The other one is exchanging the closest identifications with other nodes. Finally, each node calculates the average spacing of the closest identifications collected to estimate network size. Compared with existing approaches, extensive experiments show that CANSE provides accurate estimation values quickly in various dynamic topologies. © 2010 IEEE.

关键词： Topology

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Media access control protocol based on hybrid antennas in ad hoc networks

Media access control protocol based on hybrid antennas in ad...

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International Conference on Autonomic and Trusted Computing

作者： Ding, Yanrong Wang, Xiaodong Shen, Hu Guo, Pengyu National Key Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology Changsha 410073 China

ISBN: (纸本)9780769542720

Nested Circular Directional MAC, a modified medium access control protocol of DMAC protocol, is proposed in this paper to support both directional antennas and omni-directional antennas simultaneously in one Ad Hoc network. Omni-directional antennas follow the RTS/CTS mechanism which is multi-hop and directional antennas follow the DRTS/DCTS mechanism, ensuring the asymmetric communication effectively. In order to resolve new deafness problem and hidden terminal problem, the directional antennas also use circular DRTS and nested antenna circumrotation. Simulation results show that NCDMAC supports hybrid antennas effectively and is better than MMAC and Circular-MAC in terms of increasing throughput, but it also increases the communication delay. © 2010 IEEE.

关键词： Ad hoc networks

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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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RETRACTED ARTICLE: parallel block multigrid preconditioner for 3D navier-stokes equations on unstructured grids

RETRACTED ARTICLE: Parallel block multigrid preconditioner f...

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作者： Li, Zongzhe Lu, Yao Cao, Wei Wang, Yongxian Wang, Zhenghua Parallel and Distributed Processing for National Laboratory School of Computer Science National University of Defence Lechnology Changsha Hunan 410073 China

ISBN: (纸本)9781424472369

In this paper, we explore a parallel block multigrid preconditioner based on factorization of the coefficient matrix generated in three-dimensional unstructured grids system. This preconditioner is robust with respect to the magnitude of the mesh size and the coefficient complexity, apply smoothed aggregation algebraic multigrid which using block lower-upper symmetric Gauss-Seidel(BLU-SGS) as smoother to accelerate convergent rate. We focus on this method to three-dimensional, unstructured, large-scale, parallel and NS equations' steady-state simulations. The numerical results which conducted on NACA0012 airfoil indicate that nearly optimal convergence rates and computational complexity for parallel solutions, this method also provide high speedup and efficiency for a series of processors. © 2010 IEEE.

关键词： Navier Stokes equations

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Power-efficientwork distribution method for CPU-GPU heterogeneous system

Power-efficientwork distribution method for CPU-GPU heteroge...

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IEEE International Symposium on parallel and distributed processing With Applications

作者： Wang, Guibin Ren, Xiaoguang National Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology Changsha Hunan China

ISBN: (纸本)9780769541907

As the system scales up continuously, the problem of power consumption for high performance computing (HPC) system becomes more severe. Heterogeneous system integrating two or more kinds of processors, could be better adapted to heterogeneity in applications and provide much higher energy efficiency in theory. Many studies have shown heterogeneous system is preferable on energy consumption to homogeneous system in a multi-programmed computing environment. However, how to exploit energy efficiency (Flops/Watt) of heterogeneous system for a single application or even for a single phase in an application has not been well studied. This paper proposes a power-efficient work distribution method for single application on a CPU-GPU heterogeneous system. The proposed method could coordinate inter-processor work distribution and per-processor's frequency scaling to minimize energy consumption under a given scheduling length constraint. We conduct our experiment on a real system, which equips with a multi-core CPU and a multi-threaded GPU. Experimental results show that, with reasonably distributing work over CPU and GPU, the method achieves 14% reduction in energy consumption than static mappings for several typical benchmarks. We also demonstrate that our method could adapt to changes in scheduling length constraint and hardware configurations. © 2010 IEEE.

关键词： Graphics processing unit

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Stigmergic collaboration: A sign-based perspective of stigmergy

Stigmergic collaboration: A sign-based perspective of stigme...

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2010 International Conference on Intelligent Computation Technology and Automation, ICICTA 2010

作者： Ren, Chuanjun Huang, Hongbing Jin, Shiyao National Laboratory for Parallel and Distributed Processing College of Computer Science National University of Defense Technology Changsha 410073 China

ISBN: (纸本)9780769540771

Insects build architecturally complex nests and search for remote food by collaboration work despite their limited sensors, minimal individual intelligence and the lack of a central control system. Insets' collaborations emerge as a response of the individual insects to Stigmergy. A sign-based model of Stigmergy to discuss collaboration is proposed in this paper where we picked up "sign" as a key notion to understand it. Therefore, sign is the link of all the components in a Stigmergic complex adaptive system. Based on this understanding, we propose a definition that reveals the nature of signs and exploit the significations and relationships carried by the notion of sign. Then, a sign-based model of Stigmergy is consequently reached, which captures the essentials of Stigmergy. A basic architecture of Stigmergy as well as its constituents are presented and discussed. At last, some applications of the model are discussed. © 2010 Crown Copyright.

关键词： CAS Collaboration Emergence Sign Stigmergy Emergence Volatile Oils Insecta central control system

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Routing with uncertainty in wireless mesh networks

Routing with uncertainty in wireless mesh networks

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2010 IEEE 18th International Workshop on Quality of Service, IWQoS 2010

作者： Chen, Fajun Liu, Jiangchuan Li, Zongpeng Wang, Yijie Key Laboratory of Science and Technology for National Defence of Parallel and Distributed Processing School of Computer National University of Defense Technology China School of Computing Science Simon Fraser University Canada Department of Computer Science University of Caglary Canada

ISBN: (纸本)9781424459889

Existing routing protocols for Wireless Mesh Networks (WMNs) are generally optimized with statistical link measures, while not addressing on the intrinsic uncertainty of wireless links. We show evidence that, with the transient link uncertainties at PHY and MAC layers, a pseudo-deterministic routing protocol that relies on average or historic statistics can hardly explore the full potentials of a multi-hop wireless mesh. We study optimal WMN routing using probing-based online anypath forwarding, with explicit consideration of transient link uncertainties. We show the underlying connection between WMN routing and the classic Canadian Traveller Problem (CTP) [1]. Inspired by a stochastic recoverable version of CTP (SRCTP), we develop a practical SRCTP-based online routing algorithm under link uncertainties. We study how dynamic next hop selection can be done with low cost, and derive a systematic selection order for minimizing transmission delay. We conduct simulation studies to verify the effectiveness of the SRCTP algorithms under diverse network configurations. In particular, compared to deterministic routing, reduction of end-to-end delay (51:15∼73:02%) and improvement on packet delivery ratio (99:76%) are observed.

关键词： Routing protocols

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