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

作者： Lixia Liu Gang Hu Ming Xu Yuxing Peng National Key Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology Changsha China Department of Networks Engineering School of Computer National University of Defense Technology Changsha China

In the relay-trading mode of wireless cognitive radio networks the secondary user (SU) can achieve a promised spectrum access opportunity by relaying for the primary user (PU). How to utilize the exchanged resource efficiently and fairly is an interesting and practical problem. In this paper we proposed a cooperative spectrum sharing strategy (RT-CSS) for the relay-trading mode from the fairness view. The cooperative SUs are gathered in a cooperative sharing group (CSG), and contribution metric (CM) is proposed to measure each CSG member's contribution to CSG as well as benefit from CSG. The adjustment of CM can guarantee the fairness and efficiency of spectrum sharing. The numerical simulation shows that RT-CSS can achieve better performance than the sense-uncooperative mode.

关键词： Relays Cognitive radio Measurement Qualifications Wireless sensor networks Radio networks

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Research on Malicious Code Detection Based on Least-squares Estimation

Research on Malicious Code Detection Based on Least-squares ...

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International Conference on computer Science and Electronics engineering (ICCSEE)

作者： Yunlong Wu Chen Chen Huiquan Wang Xinhai Xu Jie Zhou National Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology Changsha Hunan P. R. China

Malicious code detection based on behaviors is the development direction of anti-virus techniques. However, the current detection methods based on this theory expose several problems such as the unclearness of behavior sequence analysis and the high false negatives. For this situation, this paper proposes a malicious code detection method based on least-squares estimation. In this method, it correlates program behaviors with time and subject-object, and then constitutes an accurate and complete behavior sequence. It can provide a preprocessing method for the subsequent detection. In order to improve the accuracy and intelligence of malicious code detection, we introduce the concept of expert subjective degree. By modeling malicious samples based on least-squares estimation we can train the Expert Subjective Degree Vector (ESDV) and simulate experts to judge the threat values of malicious codes. Experiments show that this method is more accurate than the current ways to detect the malicious codes which execute themselves in sub-period and sub-process ways, so it can be used as an effective complement of the current anti-virus software.

关键词： Correlation Mathematical model Equations Estimation Libraries computers Monitoring

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Reduced complexity tree-structured conditional random field for all-words word sense disambiguation

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Journal of Computational Information Systems 2012年第3期8卷 1177-1186页

作者： Zhou, Yun Wang, Ting Wang, Zhiyuan Xie, Songxian Computer School National University of Defense Technology Changsha 410073 China National Key Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha 410073 China

In this paper, we apply tree-structured conditional random field (TCRF) to all-words word sense disambiguation (WSD), where the graphical structure of TCRF is the dependency syntax tree produced by Minipar. The extremely large label space and high time complexity of TCRF hinders its application in semantic parsing, especially in all-words WSD, and we focus on reducing the time complexity of TCRF in this paper. The running time of TCRF is reduced significantly by edge feature selection and parallelization in training phase and beam search strategy in decoding phase. We evaluate the TCRF method on the English all-words task of Senseval-3, and the F1 value of TCRF method is 0.668, which outperforms the best result 0.652 in Senseval-3. For convenience of comparison, our training set only includes a part of Semcor, which reserves the space for improvement. Furthermore, the practical problem in the fields of information retrieval and natural language processing, often has a large label space and tree-structured information, which can also be solved by the TCRF method proposed in this paper. 1553-9105/Copyright © 2012 Binary Information Press.

关键词： Semantics

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Server-uncertain spectrum trading in cognitive radio networks: A queueing-theoretic modeling approach

Server-uncertain spectrum trading in cognitive radio network...

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International Conference on Cognitive Radio Oriented Wireless Networks and Communications

作者： Lixia Liu Gang Hu Ming Xu Yuxing Peng National Key Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha China Department of Network Engineering College of Computer National University of Defense Technology Changsha China

Spectrum trading is the promising method to improve spectrum efficiency from the perspective of economics. In this paper we propose a queueing-theory based spectrum trading model, where the primary user plays the server role providing spectrum to the secondary user who acts as the customer. The most significant challenge is how to optimize the spectrum trading model considering the server uncertainty which includes service state, service time, service area, service content and service price. We design a STACP queueing model according to the server attributes, so that the secondary user can choose the right queue quickly and reasonably according to its demand. Moreover, we further analyze the optimizing strategies for STACP model which can maximize the profit of the primary user and minimize the service cost of the secondary user. The simulation results demonstrate the analysis results.

关键词： Servers Uncertainty Loss measurement Queueing analysis Economics Analytical models Business

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A Programming Language Approach to Internet-Based Virtual Computing Environment

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Journal of computer Science & Technology 2011年第4期26卷 600-615页

作者：王戟沈锐王怀民 National Laboratory for Parallel and Distributed Processing School of ComputerNational University of Defense Technology

There is an increasing need to build scalable distributed systems over the Internet infrastructure. However the development of distributed scalable applications suffers from lack of a wide accepted virtual computing environment. Users have to take great efforts on the management and sharing of the involved resources over Internet, whose characteristics are intrinsic growth, autonomy and diversity. To deal with this challenge, Internet-based Virtual Computing Environment （iVCE） is proposed and developed to serve as a platform for distributed scalable applications over the open infrastructure, whose kernel mechanisms are on-demand aggregation and autonomic collaboration of resources. In this paper, we present a programming language for iVCE named Owlet. Owlet conforms with the conceptual model of iVCE, and exposes the iVCE to application developers. As an interaction language based on peer-to-peer content-based publish/subscribe scheme, Owlet abstracts the Internet as an environment for the roles to interact, and uses roles to build a relatively stable view of resources for the on-demand resource aggregation. It provides language constructs to use 1） distributed event driven rules to describe interaction protocols among different roles, 2） conversations to correlate events and rules into a common context, and 3） resource pooling to do fault tolerance and load balancing among networked nodes. We have implemented an Owlet compiler and its runtime environment according to the architecture of iVCE, and built several Owlet applications, including a peer-to-peer file sharing application. Experimental results show that, with iVCE, the separation of resource aggregation logic and business logic significantly eases the process of building scalable distributed applications.

关键词： distributed architecture distributed programming on demand aggregation virtual computing

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Speeding up the MATLAB complex networks package using graphic processors

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Chinese Physics B 2011年第9期20卷 460-467页

作者：张百达唐玉华吴俊杰李鑫 National laboratory for Parallel and Distributed Processing School of ComputerNational University of Defense Technology Department of Computer Science and Technology School of ComputerNational University of Defense Technology

The availability of computers and communication networks allows us to gather and analyse data on a far larger scale than previously. At present, it is believed that statistics is a suitable method to analyse networks with millions, or more, of vertices. The MATLAB language, with its mass of statistical functions, is a good choice to rapidly realize an algorithm prototype of complex networks. The performance of the MATLAB codes can be further improved by using graphic processor units （GPU）. This paper presents the strategies and performance of the GPU implementation of a complex networks package, and the Jacket toolbox of MATLAB is used. Compared with some commercially available CPU implementations, GPU can achieve a speedup of, on average, 11.3x. The experimental result proves that the GPU platform combined with the MATLAB language is a good combination for complex network research.

关键词： complex networks graphic processors unit MATLAB Jacket Toolbox

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Topology-Aware Deployment of Scientific Applications in Cloud Computing

Topology-Aware Deployment of Scientific Applications in Clou...

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IEEE International Conference on Cloud Computing, CLOUD

作者： Pei Fan Zhenbang Chen Ji Wang Zibin Zheng Michael R. Lyu National Laboratory for Parallel & Distributed Processing National University of Defense Technology Changsha P.R.China Dept. of Computer Science & Engineering The Chinese University of Hong Kong Hong Kong China

Nowadays, more and more scientific applications are moving to cloud computing. The optimal deployment of scientific applications is critical for providing good services to users. Scientific applications are usually topology-aware applications. Therefore, considering the topology of a scientific application during the development will benefit the performance of the application. However, it is challenging to automatically discover and make use of the communication pattern of a scientific application while deploying the application on cloud. To attack this challenge, in this paper, we propose a framework to discover the communication topology of a scientific application by pre-execution and multi-scale graph clustering, based on which the deployment can be optimized. Comprehensive experiments are conducted by employing a well-known MPI benchmark and comparing the performance of our method with those of other methods. The experimental results show the effectiveness of our topology-aware deployment method.

关键词： Topology Clustering algorithms Benchmark testing Cloud computing Partitioning algorithms Clustering methods Throughput

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Betweenness-based algorithm for a partition scale-free graph

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Chinese Physics B 2011年第11期20卷 556-564页

作者：张百达吴俊杰唐玉华周静 National Laboratory for Parallel and Distributed Processing School of ComputersNational University of Defense Technology Department of Computer Science and Technology School of ComputersNational University of Defense Technology

Many real-world networks are found to be scale-free. However, graph partition technology, as a technology capable of parallel computing, performs poorly when scale-free graphs are provided. The reason for this is that traditional partitioning algorithms are designed for random networks and regular networks, rather than for scale-free networks. Multilevel graph-partitioning algorithms are currently considered to be the state of the art and are used extensively. In this paper, we analyse the reasons why traditional multilevel graph-partitioning algorithms perform poorly and present a new multilevel graph-partitioning paradigm, top down partitioning, which derives its name from the comparison with the traditional bottom-up partitioning. A new multilevel partitioning algorithm, named betweenness-based partitioning algorithm, is also presented as an implementation of top-down partitioning paradigm. An experimental evaluation of seven different real-world scale-free networks shows that the betweenness-based partitioning algorithm significantly outperforms the existing state-of-the-art approaches.

关键词： graph partitioning betweenness-based partitioning algorithm scale free network

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Security Issues and Solutions in Cloud Computing

Security Issues and Solutions in Cloud Computing

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International Conference on distributed Computing Systems Workshop

作者： Pengfei You Yuxing Peng Weidong Liu Shoufu Xue National Key Laboratory for Parallel and Distributed Processing School of Computer Science National University of Defense Technology Changsha China Jiangsu Automation Research Institute Jiangsu China CPLA Air Defence Forces Command Academy Zhengzhou Henan China

Recently, Cloud computing, as one of the hottest words in IT world, has drawn great attention. Many IT companies such as IBM, Google, Amazon, Microsoft, Yahoo and others vigorously develop cloud computing systems and related products to customers. However, there are still some difficulties for customers to adopt cloud computing, in which many security issues exist, because data for a customer is stored and processed in cloud, not in a local machine. This paper briefly introduces cloud computing and its key concepts. In particularly, we intend to discuss security requirements and security issues involving data, application and virtualization in cloud computing, as well as current solutions to these issues.

关键词： Cloud computing Computational modeling Virtual machine monitors Operating systems Cryptography

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Towards estimating expected sizes of probabilistic skylines

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Science China(Information Sciences) 2011年第12期54卷 2574-2584页

作者： YANG YongTao & WANG YiJie National Key laboratory for parallel and distributed processing, school of computer, National University of Defense Technology, Changsha 410073, China 1. National Key Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology Changsha 410073 China

We consider the maximal vector problem on uncertain data, which has been recently posed by the study on processing skyline queries over a probabilistic data stream in the database context. Let D n be a set of n points in a d-dimensional space and q (0 < q 1) be a probability threshold; each point in D n has a probability to occur. Our problem is concerned with how to estimate the expected size of the probabilistic skyline, which consists of all the points that are not dominated by any other point in D n with a probability not less than q. We prove that the upper bound of the expected size is O(min{n, (- ln q)(ln n) d-1 }) under the assumptions that the value distribution on each dimension is independent and the values of the points along each dimension are distinct. The main idea of our proof is to find a recurrence about the expected size and solve it. Our results reveal the relationship between the probability threshold q and the expected size of the probabilistic skyline, and show that the upper bound is poly-logarithmic when q is not extremely small.

关键词： probabilistic skyline probabilistic data streams expected size

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