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Towards a new methodology for estimating available bandwidth on network paths

7th International Symposium on Advanced parallel processing Technologies, APPT 2007

作者： Lv, Shaohe Wang, Xiaodong Zhou, Xingming Yin, Jianping National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha Hunan 410073 China

ISBN: (纸本)9783540768364

This paper presents a novel methodology, called COPP, to estimate available bandwidth over a given network path. COPP deploys a particular probe scheme, namely chirp of packet pairs, which is composed of several packet pairs with decremental inter-packet spacing. After each pair chirp is received, COPP discovers all turning points, e.g. such packet pair that is interfered more seriously in contrast to its adjacent pairs, and give each point a distinct weight according to the degree to which the pair and its consecutive neighbors are interfered by cross traffic to yield an estimate. The final estimate is the average of the results of all chirps in a measurement episode. Two decision rules are developed to determine whether a packet pair is turning point We test COPP in various simulations and find that COPP can provide accurate results with relatively less overhead while adapt to network variations rapidly. © Springer-Verlag Berlin Heidelberg 2007.

关键词： Bandwidth

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Scalable distributed resource information service for internet-based virtual computing environment

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Ruan Jian Xue Bao/Journal of Software 2007年第8期18卷 1933-1942页

作者： Zhang, Yi-Ming Li, Dong-Sheng Lu, Xi-Cheng National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha 410073 China

Based on the characteristics of evolution, autonomy and diversity of Internet resources, researchers recently proposed to realize the publication and query of Internet resource information through common DHT (distributed Hash table) information services. However, current research on resource information services is insufficient in generality, usability and adaptability. Aiming at the needs of iVCE (Internet-based virtual computing environment) for resource aggregation, the SDIRIS (scalable distributed resource information service) is proposed to construct. First, the adaptive DHT (A-FissionE) infrastructure is presented, which supports to adapt to different system scale and stability transparently. Second, the MR-FissionE, which is an efficient multiple-attribute range query algorithm, is presented based on A-FissionE. Theoretical analysis and experimental results prove that SDIRIS can realize resource information publication and query efficiently.

关键词： Information services

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The detection and assessment of possible RNA secondary structure using multiple sequence alignment

Proceedings of the ACM Symposium on Applied Computing

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Proceedings of the ACM Symposium on Applied Computing 2007年 133-137页

作者： Fang, Xiaoyong Wang, Zhenghua Luo, Zhigang Yuan, Bo Ding, Fan National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha 410073 China Department of Biomedical Informatics College of Medicine and Public Health Ohio State University Columbus OH 43210-1239 United States

ISBN: (纸本)1595934804;9781595934802

We here devise a new method for detecting and assessing RNA secondary structure by using multiple sequence alignment. The central idea of the method is to first detect conserved stems in the alignment using a special matrix and then assess them by evaluating the ratio of the signal to the noise. We tested the method on data sets composed of pairwise and three-way alignments of known ncRNAs. For the pairwise tests, our method has sensitivity 61.42% and specificity 97.05% for structural alignments, and sensitivity 42.05% and specificity 98.15% for BLAST alignments. For the three-way tests, our method has sensitivity 65.17% and specificity 97.96% for structural alignments, and sensitivity 40.70% and specificity 97.87% for CLUSTALW alignments. Our method can detect conserved secondary structures in gapped or ungapped RNA alignments. Copyright 2007 ACM.

关键词： RNA

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Efficient Rate Adaptation in Multi-rate 802.11 Networks

Efficient Rate Adaptation in Multi-rate 802.11 Networks

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IEEE Symposium on Computers and Communications (ISCC)

作者： Shaohe Lv Xiaodong Wang Xingming Zhou Chi Liu National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha Hunan China

Given the multi-rate option in most 802.11 standards, rate adaptation based on dynamic channel condition is crucial to the system performance. This paper presents an efficient rate adaptation mechanism at MAC layer, called ERA, to improve the transport layer throughput. Such scheme raises the transmission rate aggressively, e.g., upon only a few consecutive successful transmissions. In opposite, we reduce the transmission rate more cautiously only when the station encounters severe consecutive frame losses or relatively high loss ratio at MAC layer. ERA also attempts to protect the performance under steady condition without losing the ability to respond to the channel variation quickly. We evaluate ERA using NS-2 simulations and find that it performs better than or at least similarly with many other proposals in various scenarios. ERA is a sender-based method and requires minor modification at sender side only, thus completely standard-compliant and very easy to be implemented and deployed.

关键词： System performance Throughput Propagation losses Protection Laboratories distributed processing Performance evaluation Proposals Physical layer Data mining

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Compositional Verification of UML Dynamic Models

Compositional Verification of UML Dynamic Models

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Asia-Pacific Conference on Software Engineering

作者： Wei Dong Ji Wang Zhichang Qi Ni Rong School of Computer National University of Defense Technology China National Laboratory for Parallel and Distributed Processing China

UML dynamic models are important for software analysis and design. Verifying UML dynamic models to find design errors earlier is a key issue for ensuring software quality. Because of the characteristics such as concurrency and hierarchy, model checking of UML Statecharts and collaboration diagrams faces the problem of state explosion. In this paper, UML Statecharts is firstly structurally expressed by hierarchical automata and its semantics for open systems is introduced. Then, the synchronization composition of objects in UML collaboration diagrams is expatiated, based on which the global system behaviors can be constructed. Based on hierarchical automata and simulation relation between semantics structures, the compositional rules for verifying concurrent object systems are proposed. It makes possible that the construction of global state space will be unnecessary in model checking of UML collaboration diagrams. The hierarchical structures of UML Statecharts are also brought into the compositional verification, which makes the model checking of implementation models can be carried out through replacing detailed components by abstract specifications.

关键词： Unified modeling language Concurrent computing Automata State-space methods Explosions International collaboration Software systems Software engineering distributed computing Laboratories

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Self-Learning Rate Adaptation in Multi-rate 802.11 Networks

Self-Learning Rate Adaptation in Multi-rate 802.11 Networks

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第三届IEEE无线通讯、网络技术暨移动计算国际会议

作者： Shaohe Lv Xiaodong Wang Xingming Zhou Chi Liu National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha Hunan China 410073

Given the multi-rate option in most 802.11 standards, rate adaptation based on dynamic channel condition is crucial to the system performance. This paper presents an efficient self-learning rate adaptation mechanism at MAC layer, called SLRA. SLRA takes both the temporal or spatial correlation and cha- nge into account. The rate selection has two steps: one is to evaluate the performance of current rate and decide whether to adjust the rate;the second is to calib- rate the decision according to the historical experiments of rate adjustment at similar channel status. We evaluate SLRA in 802.11 network and find that it can choose the right rate at most time and performs better than other sender-side adaptation schemes.

关键词： History Performance evaluation Throughput System performance Switches Transmitters Laboratories distributed processing Physical layer Robustness

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A push-based prefetching for cooperative caching RAM Grid

A push-based prefetching for cooperative caching RAM Grid

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International Conference on parallel and distributed Systems (ICPADS)

作者： Rui Chu Nong Xiao Lei Chen Xicheng Lu National Laboratory for Parallel and Distributed Processing ChangSha Hunan China Hong Kong University of Science and Technology Kowloon Hong Kong China

As an innovative distributed computing technique for sharing the memory resources in high-speed network, RAM Grid exploits the distributed free nodes, and provides remote memory for the nodes which are short of memory. One of the RAM Grid systems named DRACO, tries to provide cooperative caching to improve the performance of the user node which has mass disk I/O but lacks local memory. However, the performance of DRACO is constrained with the network communication cost. In order to hide the latency of remote memory access and improve the caching performance, we proposed using push- based prefetching to enable the caching providers to push the potential useful memory pages to the user nodes. Specifically, for each caching provider, it employs sequential pattern mining techniques, which adapts to the characteristics of memory page access sequences, on locating useful memory pages for prefetching. We have verified the effectiveness of the proposed method through system analysis and trace-driven simulations.

关键词： Prefetching Cooperative caching Random access memory Read-write memory Delay High-speed networks File systems Costs Laboratories distributed processing

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Collaborative Search in Large-scale Unstructured Peer-to-Peer Networks

Collaborative Search in Large-scale Unstructured Peer-to-Pee...

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International Conference on parallel processing (ICPP)

作者： Yiming Zhang Dongsheng Li Lei Chen Xicheng Lu National Laboratory for Parallel and Distributed Processing National University of Defense Technology China Department of Computer Science Hong Kong University of Science and Technology Hong Kong China

Searching in large-scale unstructured peer-to-peer networks is challenging due to the lack of effective hint information to guide queries. In this paper, we propose POP, a parallel, collaborative and Probabilistic search mechanism, in which query messages are viewed as search units to collaborate with each other and aggregate the distributed hints during the search process. A scheme called distributed Bloom filter (DBF) is presented to propagate the hints with a bandwidth-aware manner, in which a node divides the received Bloom filter vector into subvectors and disseminates the fragments to its neighbors according to their bandwidth capacity. The effectiveness of POP is demonstrated through theoretical analysis and extensive simulations.

关键词： Large-scale systems Peer to peer computing Bandwidth Information filtering Information filters Analytical models Aggregates Space technology International collaboration Laboratories

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Are filter methods very effective in gene selection of microarray data?

Are filter methods very effective in gene selection of micro...

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IEEE International Conference on Bioinformatics and Biomedicine Workshops (BIBMW)

作者： Zhou-Jun Li Li-Juan Zhang Huo-Wang Chen School of Computer Science & Engineering Beihang University Beijing China National Laboratory for Parallel and Distributed Processing Changsha China

Feature (gene) selection is a frequently used preprocessing technology for successful cancer classification task in microarray gene expression data analysis. Widely used gene selection approaches are mainly focused on the filter methods. Filter methods are usually considered to be very effective and efficient for high-dimensional data. This paper reviews the existing filter methods, and shows the performance of the representative algorithms on microarray data by extensive experimental study. Surprisingly, the experimental results show that filter methods are not very effective on microarray data. We analyze the cause of the result and provide the basic ideas for potential solutions.

关键词： Filters Data analysis Classification algorithms Cancer Algorithm design and analysis Computer science Data engineering Laboratories distributed processing Gene expression

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Research on the weighted reconstruction of metabolic networks

Research on the weighted reconstruction of metabolic network...

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第五届中国蛋白质组学大会暨首届粤港蛋白质组学学术交流会

作者： Zhou Tingting Wang Zhenghua Chan, K.C.C. Beijing Proteome Research Center BeijingP.R.China102206 National Laboratory for Parallel & Distributed ProcessingNational University of Deference and TechnologyChangshaP.R.China 410073 Department of computingthe HongKong Polytechnic UniversityHonghumHongkong Department of computing the HongKong Polytechnic UniversityHonghumHongkong National Laboratory for Parallel & Distributed Processing National University of Deference and TechnologyChangshaP.R.China 410073

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