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14th International Conference on Enterprise Information systems, ICEIS 2012

作者： Wang, Zhaoxia Wen, Lijie Zhu, Xiaochen Liu, Yingbo Wang, Jianmin School of Software Tsinghua University Beijing 100084 China Department of Computer Science and Technology Tsinghua University Beijing 100084 China Key Lab. for Information System Security Ministry of Education Beijing 100084 China National Laboratory for Information Science and Technology Beijing 100084 China Logistical Engineering University Chongqing 400016 China

ISBN: (纸本)9789898565105

Workflow testing is an important method of workflow analysis in design time. A challenging problem with trace-oriented test data generation in particular and trace-based workflow analysis in general is the existence of infeasible traces for which there is no input data for them to be executed. In this paper we build on the theory of workflow nets and introduce workflow nets where transitions have conditions associated with them. We then demonstrate that we can determine which execution traces, that are possible according to the control-flow dependencies, are actually possible taking the data perspective into account. This way we are able to more accurately determine in design time the infeasible traces caused by the correlation between transition conditions along this trace. Finally, we provide a solution to automatically detecting the shortest infeasible trace.

关键词： Infeasible traces Process models Workflow analysis

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Finding and evaluating the community structure in semantic peer-to-peer overlay networks

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science China(Information sciences) 2011年第7期54卷 1340-1351页

作者： CHEN HanHua & JIN Hai services computing technology and system laboratory,Cluster and Grid computing laboratory,school of computer science and technology,Huazhong University of science and technology,Wuhan 430074,China 1. Services Computing Technology and System Laboratory Cluster and Grid Computing Laboratory School of Computer Science and Technology Huazhong University of Science and Technology Wuhan 430074 China

Recently much attention has been paid to semantic overlay networks for information retrieval in large scale peer-to-peer networks,and much research work on semantic overlay protocols and searching algorithms has been done and the results indicate that semantic overlay is efficient for content searching in peer-to-peer ***,very limited work has been done to analyze and evaluate the characteristics of semantic overlay *** this paper we identify a natural property of semantic overlay networks,the community *** propose a mathematical model to evaluate the property of community structure of semantic P2P overlay networks.A heuristic algorithm is designed to optimize the community *** the evaluation model we compare the SemreX semantic overlay with the Gnutella *** demonstrate that a SemreX overlay network has the distinctive community structure feature,while a Gnutella-like network does *** also simulate a simple flooding protocol in both overlays to show that the overlay with community structure is more efficient for content searching.

关键词： peer-to-peer community structure semantic overlay

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Asymptotic throughput for large-scale wireless networks with general node density

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Wireless Networks 2012年第5期19卷 559-575页

作者： Cheng Wang Changjun Jiang Xiang-Yang Li Yunhao Liu Department of Computer Science Tongji University Shanghai China Key Laboratory of Embedded System and Service Computing Ministry of Education Shanghai China The Tsinghua National Laboratory for Information Science and Technology (TNLIST) Department of Computer Science and Engineering Tongji University Shanghai China The Department of Computer Science Illinois Institute of Technology Chicago USA The TNLIST and School of Software Tsinghua University Beijing China CSE The Hong Kong University of Science and Technology Kowloon Hong Kong

We study the asymptotic throughput for a large-scale wireless ad hoc network consisting of n nodes under the generalized physical model. We directly compute the throughput of multicast sessions to unify the unicast and broadcast throughputs. We design two multicast schemes based on the so-called ordinary arterial road system and parallel arterial road system, respectively. Correspondingly, we derive the achievable multicast throughput by taking account of all possible cases of n s = ω(1) and 1 ≤ n d ≤ n − 1, rather than only the cases of $$n_s=\Uptheta(n)$$ as in most related works, where n s and n d denote the number of sessions and the number of destinations of each session, respectively. Furthermore, we consider the network with a general node density $$\lambda \in [1,n]$$ , while the models in most related works are either random dense network (RDN) or random extended network (REN) where the density is λ = n and λ = 1, respectively, which further enhances the generality of this work. Particularly, for the special case of our results by letting λ = 1 and $$n_s=\Uptheta(n)$$ , we show that for some regimes of n d , the multicast throughputs achieved by our schemes are better than those derived by the well-known percolation-based schemes.

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Damping based multi-path traffic allocation algorithm for wireless networks

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Journal of Computational Information systems 2012年第10期8卷 4169-4175页

作者： Lu, Xu Yu, Ruiguo Dong, Wenyong Lei, Ming Hao, Lianxiu School of Computer Science and Technology Tianjin University Tianjin 300072 China Computer School Wuhan University Wuhan 430079 China Tianjin Key Laboratory of Intelligence Computing and Novel Software Technology Tianjin University of Technology Tianjin 300191 China Key Laboratory of Computer Vision and System Ministry of Education Tianjin 300191 China School of Electronic Information Engineering Tianjin University Tianjin 300072 China

In physics, damping is any effect that tends to reduce the amplitude of oscillations in an oscillatory system. Inspired by this, we present a new traffic allocation algorithm for Wireless Networks in order to limit the packet delay variance. We refer to our algorithm as the damping based traffic allocation algorithm (DBTA). DBTA computes the queuing delay and queuing delay variance, configures system parameters, and finally reduces the amplitude of delay variations. We realize DBTA based on Dynamic Source Routing (DSR) protocol. Performance comparison of DBTA with DSR using Network Simulator (NS-2) simulation shows that DBTA can achieve a remarkable improvement in decreasing the packet delay variance. © 2011 by Binary Information Press.

关键词： Damping

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Priv-Code: Preserving privacy against traffic analysis through network coding for multihop wireless networks

Priv-Code: Preserving privacy against traffic analysis throu...

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IEEE Annual Joint Conference: INFOCOM, IEEE computer and Communications Societies

作者： Zhiguo Wan Kai Xing Yunhao Liu MOE Key Laboratory for Information System Security School of Software Tsinghua National Laboratory for Information Science and Technology Tsinghua University China School of Computer Science and Technology University of Science and Technology China Department of Computer Science and Engineering HKUST Hong Kong China

ISBN: (纸本)9781467307734

Traffic analysis presents a serious threat to wireless network privacy due to the open nature of wireless medium. Traditional solutions are mainly based on the mix mechanism proposed by David Chaum, but the main drawback is its low network performance due to mixing and cryptographic operations. We propose a novel privacy preserving scheme based on network coding called Priv-Code to counter against traffic analysis attacks for wireless communications. Priv-Code is able to provide strong privacy protection for wireless networks as the mix system because of its intrinsic mixing feature, and moreover, it can achieve better network performance owing to the advantage of network coding. We first construct a hypergraph-based network coding model for wireless networks, under which we formalize an optimization problem whose objective function is to make each node have identical transmission rate. Then we provide a decentralized algorithm for this optimization problem. After that we develop an information theoretic metric for privacy measurement using entropy, and based on this metric we demonstrate that Priv-Code achieves stronger privacy protection than the mix system while achieving better network performance.

关键词： Optimization

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Self-map building in wireless sensor network based on TDOA measurements

Self-map building in wireless sensor network based on TDOA m...

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2012 IEEE International Conference on Multisensor Fusion and Integration for Intelligent systems, MFI 2012

作者： Liu, Shuanglong Tang, Yuchao Zhang, Chun Yue, Shigang Institute of Microelectronics National Laboratory for Information Science and Technology Tsinghua University Beijing 100084 China Institute for Information and System Science Xi'an Jiaotong University Xi'an 710049 China School of Computer Science University of Lincoln Lincoln LN6 7TS United Kingdom

ISBN: (纸本)9781467325110

Node localization has long been established as a key problem in the sensor networks. Self-mapping in wireless sensor network which enables beacon-based systems to build a node map on-the-fly extends the range of the sensor network's applications. A variety of self-mapping algorithms have been developed for the sensor networks. Some algorithms assume no information and estimate only the relative location of the sensor nodes. In this paper, we assume a very small percentage of the sensor nodes aware of their own locations, so the proposed algorithm estimates other node's absolute location using the distance differences. In particular, time difference of arrival (TDOA) technology is adopted to obtain the distance difference. The obtained time difference accuracy is 10ns which corresponds to a distance difference error of 3m. We evaluate self-mapping's accuracy with a small number of seed nodes. Overall, the accuracy and the coverage are shown to be comparable to those achieved results with other technologies and algorithms. © 2012 IEEE.

关键词： Time difference of arrival

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Design and fabrication of PTFE-filled waveguide components by SR direct etching

Design and fabrication of PTFE-filled waveguide components b...

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作者： Kishihara, Mitsuyoshi Ikeuchi, Hiroaki Utsumi, Yuichi Kawai, Tadashi Ohta, Isao Faculty of Computer Science and System Engineering Okayama Prefectural University Soja-shi 719-1197 Japan Graduate School of Engineering University of Hyogo Himeji-shi 671-2201 Japan Laboratory of Advanced Science and Technology for Industry University of Hyogo Hyogo-ken 678-1205 Japan

The metallic waveguide is one of many effective media for millimeter- and submillimeter-waves because of the advantage of its lowloss nature. This paper describes the fabrication method of PTFE-filled waveguide components with the use of the SR (synchrotron radiation) direct etching process of PTFE, sputter deposition of metal, and electroplating. PTFE is known as a difficult material to process with high precision. However, it has been reported that PTFE microstructures can be fabricated by the direct exposure to SR. First, an iris-coupled waveguide BPF with 5-stage Chebyshev response is designed and fabricated for the Q-band. It is demonstrated that the present process is applicable for the fabrication of the practical components inclusive of narrow patterns. Then, a cruciform 3 dB coupler with air-filled posts is designed and fabricated for the Q-band. Directivity and matched state of the coupler can be realized by "holes" in the dielectric material. The measurement results are also shown. Copyright © 2012 The Institute of Electronics, Information and Communication Engineers.

关键词： Bandpass filters

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A distributed taxi advisory system

A distributed taxi advisory system

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International Conference on ITS Telecommunications (ITST)

作者： Fai Cheong Choo Mun Choon Chan Akhihebbal L. Ananda Li-Shiuan Peh School of Computing National University of Singapore Singapore Computer Science and Artificial Intelligence Laboratory Massachusetts Institute of Technology USA

This paper presents a distributed taxi advisory dispatch system (TADS) that estimates regions where the demand for taxis exceed the supply of free taxis. Taxis are given advisories to move into these regions to ensure a better balance between number of waiting clients and free taxis overall. TADS performs the following tasks: (1) estimates system states (number of free taxis and waiting clients), (2) generates appropriate number of advisory tokens and, (3) distributes advisory tokens. We perform evaluation of our proposed system based on traces obtained from a large Singapore taxi company that operates more than 15,000 taxis. Our results show that TADS can reduce the number of clients with wait times longer than 60 minutes by over 30%.

关键词： Lead Global Positioning system IEEE 802.11 Standards

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SLA-Driven adaptive resource allocation for virtualized servers

SLA-Driven adaptive resource allocation for virtualized serv...

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作者： Zhang, Wei Ruan, Li Zhu, Mingfa Xiao, Limin Liu, Jiajun Tang, Xiaolan Mei, Yiduo Song, Ying Sun, Yuzhong State Key Laboratory of Software Development Environment Beijing 100191 China School of Computer Science and Engineering Beihang University Beijing 100191 China China Center Beijing 100044 China Istitute of Computing Technology Chinese Academy of Sciences Beijing 100190 China

In order to reduce cost and improve efficiency, many data centers adopt virtualization solutions. The advent of virtualization allows multiple virtual machines hosted on a single physical server. However, this poses new challenges for resource management. Web workloads which are dominant in data centers are known to vary dynamically with time. In order to meet application's service level agreement (SLA), how to allocate resources for virtual machines has become an important challenge in virtualized server environments, especially when dealing with fluctuating workloads and complex server applications. User experience is an important manifestation of SLA and attracts more attention. In this paper, the SLA is defined by server-side response time. Traditional resource allocation based on resource utilization has some drawbacks. We argue that dynamic resource allocation directly based on real-time user experience is more reasonable and also has practical significance. To address the problem, we propose a system architecture that combines response time measurements and analysis of user experience for resource allocation. An optimization model is introduced to dynamically allocate the resources among virtual machines. When resources are insufficient, we provide service differentiation and firstly guarantee resource requirements of applications that have higher priorities. We evaluate our proposal using TPC-W and Webbench. The experimental results show that our system can judiciously allocate system resources. The system helps stabilize applications' user experience. It can reduce the mean deviation of user experience from desired targets. Copyright © 2012 The Institute of Electronics, Information and Communication Engineers.

关键词： Resource allocation

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Embedding Complete Binary Trees into Locally Twisted Cubes

Embedding Complete Binary Trees into Locally Twisted Cubes

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2012 3rd International Conference on Information technology for Manufacturing systems(ITMS 2012)

作者： Yuejuan Han Jianxi Fan Lantao You Yan Wang Provincial Key Laboratory for Computer Information Processing Technology Soochow University School of Computer Science and Technology Soochow University Suzhou Industrial Park Institute Of Services Outsourcing

The locally twisted cube is a newly introduced interconnection network for parallel computing, which possesses many desirable properties. In this paper, the problem of embedding complete binary trees into locally twisted cubes is studied. Let LTQ_n（V, E） denote the n-dimensional locally twisted cube. We find the following result in this paper: for any integer n ≥ 2, we show that a complete binary tree with 2~n- 1 nodes can be embedded into the LTQ_nwith dilation 2.

关键词： Interconnection networks locally twisted cube complete binary tree embedding parallel computing

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