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International Workshop on Quality of Service

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

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). 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： Uncertainty Wireless mesh networks Delay Routing protocols Physical layer Statistics Stochastic processes Relays Computer networks Concurrent computing

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Personalized Reputation Model in Cooperative distributed Systems

Personalized Reputation Model in Cooperative Distributed Sys...

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International Conference on parallel and distributed Systems (ICPADS)

作者： Wei Liu Yang-Bin Tang Huai-Min Wang School of Computer National University of Defense Technology Changsha Hunan China National Laboratory for Parallel and Distributed Processing Changsha Hunan China Institute of Science National University of Defense Technology Changsha Hunan China

Reputation systems provide a promising way to build trust relationships between users in distributed cooperation systems, such as file sharing, streaming, distributed computing and social network, through which a user can distinguish good services or users from malicious ones and cooperate with them. However, most reputation models mainly focus on evaluating the qualities of different services in one dimension, but care less about the preferences of different users. This paper proposes a personalized reputation model which provides each user a personalized trust view on others according to his preference. In our approach, we aggregate the users' preferences with collaborative filtering method and qualify it with user similarity which is integrated into the computing of reputation values. The experimental results suggest that our model can resist possible kinds of malicious behaviors efficiently.

关键词： Computational modeling Measurement Indexes Aggregates Resists Peer to peer computing Electronic mail

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A distributed approach to consistent order delivery of concurrent events in asynchronous DVEs

ICETC 2010 - 2010 2nd International Conference on Education ...

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ICETC 2010 - 2010 2nd International Conference on Education Technology and Computer 2010年 4卷 V495-V498页

作者： Zhou, Hangjun Zhang, Wei Peng, Yuxing Li, Sikun 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 410073 China Department of Information Management Hunan College of Finance and Economics Changsha Hunan 410205 China

ISBN: (纸本)9781424463688

In large-scale asynchronous distributed virtual environments(DVEs), one of the difficult problems is to deliver the concurrent events in a consistent order at each node. Generally, the previous consistency control approaches can be classified into two categories: causal order and time stamped order. However, causal order approaches can merely preserve the cause-effect relation of events and time stamped order approaches seem intrinsically complex to be used in serverless large-scale asynchronous DVEs. In this paper, we proposed a novel distributed algorithm to identify the concurrent events and preserve the consistent order delivery of them at different nodes. Simulation studies are also carried out to compare the performance of this algorithm with that of the previous ones. The results show that the new algorithm can effectively deliver the concurrent events in consistent order at each node and is more efficient than the previous algorithms in large-scale asynchronous DVEs. © 2010 IEEE.

关键词： Virtual reality

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Using Redundant Threads for Fault Tolerance of OpenMP Programs

Using Redundant Threads for Fault Tolerance of OpenMP Progra...

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International Conference on Information Science and Applications (ICISA)

作者： Hongyi Fu Yan Ding Key Laboratory of Science and Technology for National Defence of Parallel and Distributed Processing National University of Defense Technology Changsha Hunan China Section #620 School of Computer National University of Defense Technology Changsha Hunan China

ISBN: (纸本)9781424459421

As the wide application of multi-core processor architecture in the domain of high performance computing, fault tolerance for shared memory parallel programs becomes a hot spot of research. For years, checkpointing has been the dominant fault tolerance technology in this field, and recently, many research works have been engaged with it. However, to those programs which deal with large amount of data, checkpointing may induce massive I/O transfer, which will adversely affect scalability. To deal with such a problem, this paper proposes a fault tolerance approach, making use of redundancy, for shared memory parallel programs. Our scheme avoids saving and restoring computational state during the program's execution, hence does not involve I/O operations, so presents explicit advantage over checkpointing in scalability. In this paper, we introduce our approach and the related compiler tool in detail, and give the experimental evaluation result.

关键词： Fault tolerance Checkpointing Scalability Hardware Application software Multicore processing High performance computing Laboratories distributed processing

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A consistency algorithm for causal and totally ordered event delivery in DVE

A consistency algorithm for causal and totally ordered event...

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International Conference on Computer Science and Information Technology (CSIT)

作者： Hangjun Zhou Wei Zhang Yuxing Peng Sikun Li Department of Information Management Hunan College of Finance and Economics Changsha Hunan China 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

How to preserve causal and totally ordered event delivery is an important issue in real-time serverless DVE(distributed Virtual Environment). However, most of the related works are designed to maintain causal order merely or time stamped order with intensive computation and bandwidth overhead. In this paper, we proposed a novel distributed algorithm to maintain the before-and-after relationship between events, both causal and concurrent, of DVE at each individual node. Several simulation experiments are carried out to evaluate the performance of our algorithm and the results demonstrate that the algorithm is effective in preserving causal and totally ordered event delivery and more efficient than the previous algorithms.

关键词： Artificial neural networks Silicon Educational institutions

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An Efficient Broadcast Authentication Protocol in Wireless Sensor Networks

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电子学报(英文版) 2009年第2期18卷 368-372页

作者： ZHAO Xin WANG Xiaodong YU Wanrong ZHOU Xingming National Key Laboratory of Parallel and Distributed Processing National University of Defense Technology Changsha 410073 China

Broadcast authentication is a critical security service in wireless sensor networks. A protocol named μTESLA[1] has been proposed to provide efficient authentication service for such networks. However, when applied t... 详细信息

Broadcast authentication is a critical security service in wireless sensor networks. A protocol named μTESLA^[1] has been proposed to provide efficient authentication service for such networks. However, when applied to applications such as time synchronization and fire alarm in which broadcast messages are sent infrequently, μTESLA encounters problems of wasted key resources and slow message verification. This paper presents a new protocol named GBA (Generalized broadcast authentication), for efficient broadcast authentication in these applications. GBA utilises the one-way key chain mechanism of μTESLA, but modifies the keys and time intervals association, and changes the key disclosure mechanism according to the message transmission model in these applications. The proposed technique can take full use of key resources, and shorten the message verification time to an acceptable level. The analysis and experiments show that GBA is more efficient and practical than μESLA in appli ations with various message transmission models.

关键词：无线传感器网络认证协议广播 applications practical 安全服务身份验证时间同步

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A coarse-grained reconfigurable computing architecture with loop self-pipelining

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Science in China(Series F) 2009年第4期52卷 575-587页

作者： DOU Yong WU GuiMing XU dinHui ZHOU XingMing National Laboratory for Parallel & Distributed Processing National University of Defense Technology Changsha 410073 China

Reconfigurable computing tries to achieve the balance between high efficiency of custom computing and flexibility of general-purpose computing. This paper presents the implementation techniques in LEAP, a coarse-grained reconfigurable array, and proposes a speculative execution mechanism for dynamic loop scheduling with the goal of one iteration per cycle and implementation techniques to support decoupling synchronization between the token generator and the collector. This paper also in- troduces the techniques of exploiting both data dependences of intra- and inter-iteration, with the help of two instructions for special data reuses in the loop-carried dependences. The experimental results show that the number of memory accesses reaches on average 3% of an RISC processor simulator with no memory optimization. In a practical image matching application, LEAP architecture achieves about 34 times of speedup in execution cycles, compared with general-purpose processors.

关键词： reconfigurable computing loop pipelining data driven register promotion

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SKY:Efficient peer-to-peer networks based on distributed Kautz graphs

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Science in China(Series F) 2009年第4期52卷 588-601页

作者： ZHANG YiMing LU XiCheng LI DongSheng National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha 410073 China

Many proposed P2P networks are based on traditional interconnection topologies. Given a static topology, the maintenance mechanism for node join/departure is critical to designing an efficient P2P network. Kautz graphs have many good properties such as constant degree, low congestion and optimal diameter. Due to the complexity in topology maintenance, however, to date there have been no effective P2P networks that are proposed based on Kautz graphs with base ~ 2. To address this problem, this paper presents the ＂distributed Kautz （D-Kautz） graphs＂, which adapt Kautz graphs to the characteristics of P2P networks. Using the D-Kautz graphs we further propose SKY, the first effective P2P network based on Kautz graphs with arbitrary base. The effectiveness of SKY is demonstrated through analysis and simulations.

关键词： peer-to-peer network Kautz graph constant degree topology maintenance D-Kautz graph

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Collimated electron and proton BEAM from ultraintense laser interaction with a rear hole target

Collimated electron and proton BEAM from ultraintense laser ...

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1st International Particle Accelerator Conference, IPAC 2010

作者： Yang, X.H. Ma, Y.Y. Shao, F.Q. Yu, T.P. Yin, Y. Tian, C.L. Kawata, S. Yu, M.Y. Gu, Y.Q. Xu, H. Department of Physics National University of Defense Technology Changsha 410073 China Center for Optical Research and Education Graduate School of Engineering Utsunomiya University 7-1-2 Yohtoh Utsunomiya 321-8585 Japan Department of Physics Institute for Fusion Theory and Simulation Zhejiang University Hangzhou 310027 China Laser Fusion Research Center China Academy of Engineering Physics Mianyang 621000 China National Laboratory Parallel and Distributed Processing National University of Defense Technology Changsha 410073 China

ISBN: (纸本)9789290833529

Collimated electron and proton beams from the interaction of an ultra-intense laser pulse with a rear hole target are studied by particle-in-cell (PIC) simulation. When an ultra-intense laser pulse irradiates on such a target, the hot electrons from the inner surfaces of the hole expand fast into the hole. However, the electrons at the corners expand slower and are compressed strongly. Then two intense electron jets as well as proton jets are sprayed out from the corners. The jets extend into the hole and focus along the laser propagation axis. The effects of the corner angle on the collimated proton beam are also investigated.

关键词： Hot electrons

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Mobility of internet-based virtual computing environment

Mobility of internet-based virtual computing environment

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15th International Conference on parallel and distributed Systems, ICPADS '09

作者： Shen, Siqi Wang, Ji Shen, Rui Zhang, Shengdong Fan, Pei National Laboratory for Parallel and Distributed Processing Changsha 410073 China

ISBN: (纸本)9780769539003

The Internet-based Virtual Computing Environment (iVCE) provides on-demand aggregation and autonomic collaboration mechanisms to facilitate the utilization of autonomous and dynamic Internet resources. Load balancing and fault tolerance are important issues when scheduling those transient resources. In this paper, we propose a mobility mechanism for the migration of various roles of agents in the iVCE platform. The mobility mechanism involves two parts of the iVCE platform: role container layer and event service layer. At the role container layer, a novel approach is proposed to handle the code and data mobility issue. At the event service layer, an efficient routing reconfiguration protocol is proposed based on a publish/subscribe system over DHTs to facilitate task migrations. Certain conditions must be satisfied before the migration of an agent to ensure the correctness of the whole process. Experiments are conducted to evaluate the performance of the mobility mechanism, and the experimental results show that it is suitable for implementing load balancing and fault tolerance in the iVCE. © 2009 IEEE.

关键词： Fault tolerance

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