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A fast successive over-relaxation algorithm for force-directed network graph drawing

science China(Information sciences) 2012年第3期55卷 677-688页

作者： WANG YongXian & WANG ZhengHua National Key laboratory for parallel and distributed processing, National University of Defense technology, Changsha 410073, China 1. National Key Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha 410073 China

Force-directed approach is one of the most widely used methods in graph drawing research. There are two main problems with the traditional force-directed algorithms. First, there is no mature theory to ensure the convergence of iteration sequence used in the algorithm and further, it is hard to estimate the rate of convergence even if the convergence is satisfied. Second, the running time cost is increased intolerablely in drawing largescale graphs, and therefore the advantages of the force-directed approach are limited in practice. This paper is focused on these problems and presents a sufficient condition for ensuring the convergence of iterations. We then develop a practical heuristic algorithm for speeding up the iteration in force-directed approach using a successive over-relaxation (SOR) strategy. The results of computational tests on the several benchmark graph datasets used widely in graph drawing research show that our algorithm can dramatically improve the performance of force-directed approach by decreasing both the number of iterations and running time, and is 1.5 times faster than the latter on average.

关键词： graph drawing graph layout successive over-relaxation force-directed algorithm

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Static Power Optimization for Homogeneous Multiple GPUs Based on Task Partition

Static Power Optimization for Homogeneous Multiple GPUs Base...

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2nd International Congress on Computer Applications and Computational science (CACS 2011)

作者： Lin, Yisong Tang, Tao Wang, Guibin National Laboratory of Parallel and Distributed Processing National University of Defense Technology Changsha China

ISBN: (纸本)9783642283079;9783642283086

Recently, GPU has been widely used in High Performance Computing (HPC). In order to improve computational performance, several GPUs are integrated into one computer node in practical system. However, power consumption of GPUs is very high and becomes as bottleneck to its further development. In doing so, optimizing power consumption have been draw broad attention in the research area and industry community. In this paper, we present an energy optimization model considering performance constraint for homogeneous multi-GPUs, and propose a performance prediction model when task partitioning policy is specified. Experiment results validate that the model can accurately predict the execution of program for single or multiple GPUs, and thus reduce static power consumption by the guide of task partition.

关键词： Electric power utilization

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Speculative symbolic execution

Speculative symbolic execution

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2012 IEEE 23rd International Symposium on Software Reliability Engineering, ISSRE 2012

作者： Zhang, Yufeng Chen, Zhenbang Wang, Ji National Laboratory for Parallel and Distributed Processing Department of Computing Science National University of Defense Technology Changsha China

ISBN: (纸本)9780769548883

Symbolic execution is an effective path oriented and constraint based program analysis technique. Recently, there is a significant development in the research and application of symbolic execution. However, symbolic execution still suffers from the scalability problem in practice, especially when applied to large-scale or very complex programs. In this paper, we propose a new fashion of symbolic execution, named Speculative Symbolic Execution (SSE), to speed up symbolic execution by reducing the invocation times of constraint solver. In SSE, when encountering a branch statement, the search procedure may speculatively explore the branch without regard to the feasibility. Constraint solver is invoked only when the speculated branches are accumulated to a specified number. In addition, we present a key optimization technique that enhances SSE greatly. We have implemented SSE and the optimization technique on Symbolic Pathfinder (SPF). Experimental results on six programs show that, our method can reduce the invocation times of constraint solver by 20.7% to 48.7% (with an average of 29.9%), and save the search time from 23.6% to 43.6% (with an average of 30%). © 2012 IEEE.

关键词： Java programming language

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Recent advances on trusted computing in China

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Chinese science Bulletin 2012年第35期57卷 4529-4532页

作者： DONG Wei CHEN LiQian School of Computer National University of Defense TechnologyChangsha 410073China National Laboratory for Parallel and Distributed Processing Changsha 410073China

This article highlights some recent research advances on trusted computing in China,focusing mainly on the methodologies and technologies related to trusted computing module,trusted computing platform,trusted network ... 详细信息

关键词：可信计算平台中国计算模块网络连接软件

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MemHole: An efficient black-box approach to consolidate memory in virtualization platform

MemHole: An efficient black-box approach to consolidate memo...

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41st International Conference on parallel processing Workshops, ICPPW 2012

作者： Zhang, Pengfei Chu, Rui Wang, Huaimin National Laboratory for Parallel and Distributed Processing National University of Defense Technology United States

ISBN: (纸本)9780769547954

As an important aspect of the hardware resource consolidation in virtualization environment, memory consolidation and over-commitment has been motivated by the increasing elastic computing cloud platform. The most popular consolidation technology, Memory Balloon, might introduce serious performance penalty with thrashing when guest memory usage changes dramatically. In order to overcome the drawback of Memory Balloon and guarantee the system performance, we propose Mem Hole, which provides more guest physical memory than really allocated and makes the corresponding host physical mapping undetermined until accessed, to reduce the thrashing of guest memory paging. The prototype of Mem Hole has been implemented in Xen platform and the efficiency has been shown in the preliminary evaluation. © 2012 IEEE.

关键词： Virtualization

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Exploiting attribute redundancy in extracting open source forge websites

Exploiting attribute redundancy in extracting open source fo...

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4th International Conference on Cyber-Enabled distributed Computing and Knowledge Discovery, CyberC 2012

作者： Li, Xiang Zhu, Yanxu Yin, Gang Wang, Tao Wang, Huaimin National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha China

ISBN: (纸本)9780769548104

Open Source Forge (OSF) websites provide information on massive open source software projects, extracting these web data is important for open source research. Traditional extraction methods use string matching among pages to detect page template, which is time-consuming. A recent work published in VLDB exploits redundant entities among websites to detect web page coordinates of these entities. The experiment gives good results when these coordinates are used for extracting other entities of the target site. However, OSF websites have few redundant project entities. This paper proposes a modified version of that redundancy-based method tailored for OSF websites, which relies on a similar yet weaker presumption that entity attributes are redundant rather than whole entities. Like the previous work, we also construct a seed database to detect web page coordinates of the redundancies, but all at the attribute-level. In addition, we apply attribute name verification to reduce false positives during extraction. The experiment result indicates that our approach is competent in extracting OSF websites, in which scenario the previous method can not be applied. © 2012 IEEE.

关键词： Open source software

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Providing information services for wireless sensor networks through cloud computing

Providing information services for wireless sensor networks ...

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2012 7th IEEE Asia-Pacific Services Computing Conference, APSCC 2012

作者： You, Pengfei Peng, Yuxing Gao, Hang National Key Laboratory for Parallel and Distributed Processing School of Computer Science National University of Defense Technology Changsha China

ISBN: (纸本)9780769548975

Wireless sensor networks (WSN) is a critical technology for information gathering covering many areas, including health-care, transportation, air traffic control and environment monitoring. Despite wide use, the fast increasing data emanating from WSN is not fully utilized due to the limitation for structure of WSN itself. Along with the further development of WSN, the data form which is not be efficiently managed and applied to supply information services for users. As the emerging IT technology, cloud computing supplies powerful utilization ability for IT resources, which makes many traditional applications migrate to cloud computing. In this paper, we propose a framework integrating cloud computing paradigm and WSN, which fully uses data process ability and service model for cloud computing. In the framework, data form WSN are efficiently utilized and managed, depending on which, information services for WSN are well provided to users. © 2012 IEEE.

关键词： Virtualization

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Labeled topic detection of open source software from mining mass textual project profiles

Labeled topic detection of open source software from mining ...

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1st International Workshop on Software Mining, SoftwareMining-2012 - Held in Conjunction with the 18th ACM SIGKDD Conference on Knowledge Discovery and Data Mining, KDD-2012

作者： Wang, Tao Yin, Gang Li, Xiang Wang, Huaimin National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha 410073 China

ISBN: (纸本)9781450315609

Nowadays open source software has become an indispensable basis for both individual and industrial software engineering. Various kinds of labeling mechanisms like categories and tags are used in open source communities to annotate projects and facilitate the discovery of certain software However as large amounts of software are attached with no/few labels or the existing labels are from different ontology space, it is still hard to retrieve potentially topic-relevant software. This paper highlights the valuable semantic information of project descriptions and labels, proposes labeled software topic detection LSTD a hybrid approach combining topic models and ranking mechanisms to detect and enrich the topics of software by mining the large amount of textual software profiles, which can be employed to do software categorization and tag recommendation. LSTD makes use of labeled LDA to capture the semantic correlations between labels and descriptions and then construct the label-based topic-word matrix. Based on the generated matrix and the generality of labels, LSTD designs a simple yet eficient algorithm to detect the latent topics of software that expressed as relevant and popular labels. Comprehensive evaluations are conducted on the large-scale datasets of representative open source communities and the results validate the effectiveness of LSTD.

关键词： Open source software

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Queueing analysis of the decoding process for intra-session network coding with random linear codes

Queueing analysis of the decoding process for intra-session ...

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作者： Yuan, Yuan Huang, Zhen Liu, Shengyun Peng, Yuxing National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha 410073 China

ISBN: (纸本)9783642277078

Efficient designs for intra-session network coding based practical applications largely rely on a better understanding on its queueing behaviors. However, few work devote on this topics. In this paper, we build a multi-channel batch service queueing system (MN/Dm/1) with control feedbacks to describe the decoding process of intra-session network coding with random linear codes and try to answer several fundamental questions, including for example, how to analyze braking redundancy? Under what condition is the system stable? How's quantitative relationship between the inter-decoding delay and the generation granularity? © 2012 Springer-Verlag GmbH Berlin Heidelberg.

关键词： Network coding

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Accurate and simplified prediction of L2 cache vulnerability for cost-efficient soft error protection

Accurate and simplified prediction of L2 cache vulnerability...

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作者： Cheng, Yu Ma, Anguo Zhang, Minxuan National Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology China

Soft errors caused by energetic particle strikes in on-chip cache memories have become a critical challenge for microprocessor design. Architectural vulnerability factor (AVF), which is defined as the probability that a transient fault in the structure would result in a visible error in the final output of a program, has been widely employed for accurate soft error rate estimation. Recent studies have found that designing soft error protection techniques with the awareness of AVF is greatly helpful to achieve a tradeoff between performance and reliability for several structures (i.e., issue queue, reorder buffer). Considering large on-chip L2 cache, redundancy-based protection techniques (such as ECC) have been widely employed for L2 cache data integrity with high costs. Protecting caches without accurate knowledge of the vulnerability characteristics may lead to the over-protection, thus incurring high overheads. Therefore, designing AVF-aware protection techniques would be attractive for designers to achieve a cost-efficient protection for caches, especially at early design stage. In this paper, we propose an improved AVF estimation framework for conducing comprehensive characterization of dynamic behavior and predictability of L2 cache vulnerability. We propose to employ Bayesian Additive Regression Trees (BART) method to accurately model the variation of L2 cache AVF and to quantitatively explain the important effects of several key performance metrics on L2 cache AVF. Then we employ bump hunting technique to extract some simple selecting rules based on several key performance metrics for a simplified and fast estimation of L2 cache AVF. Using the simplified L2 cache AVF estimator, we develop an AVF-aware ECC technique as an example to demonstrate the cost-efficient advantages of the AVF prediction based dynamic fault tolerant techniques. Experimental results show that compared with traditional full ECC technique, AVF-aware ECC technique reduces the L2 cache acc

关键词： Cache memory

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