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作者： Yao, Chunhui Wang, Bin Chan, Bin Yong, Junhai Paul, Jean-Claude School of Software Tsinghua University Beijing China Department of Computer Science and Technology Tsinghua University Beijing China Key Laboratory for Information System Security Ministry of Education of China Beijing China Tsinghua National Laboratory for Information Science and Technology Beijing China University of Hong Kong Hongkong Hong Kong INRIA France

Image space photon mapping has the advantage of simple implementation on GPU without pre-computation of complex acceleration structures. However, existing approaches use only a single image for tracing caustic photons, so they are limited to computing only a part of the global illumination effects for very simple scenes. In this paper we fully extend the image space approach by using multiple environment maps for photon mapping computation to achieve interactive global illumination of dynamic complex scenes. The two key problems due to the introduction of multiple images are 1) selecting the images to ensure adequate scene coverage;and 2) reliably computing ray-geometry intersections with multiple images. We present effective solutions to these problems and show that, with multiple environment maps, the image-space photon mapping approach can achieve interactive global illumination of dynamic complex scenes. The advantages of the method are demonstrated by comparison with other existing interactive global illumination methods. © 2010 The Eurographics Association and Blackwell Publishing Ltd.

关键词： Photons

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DREAM: On the reaction delay in large scale wireless networks with mobile sensors

DREAM: On the reaction delay in large scale wireless network...

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International Workshop on Quality of Service

作者： ShaoJie Tang Xiang-Yang Li Jing Yuan Cheng Wang GuiHai Chen Changjun Jiang Department of Computer Science Illinois Institute of Technology Chicago IL USA Institute of Computer Application Technology Hangzhou Dianzi University China State Key Laboratory of Novel Software Technology NanJing University NanJing China Department of Computer Science University of Tongji China

In this work, we present a monitor and rescue system utilizing hybrid networks which is a integration of stationary sensor networks and mobile sensor networks: stationary sensor networks comprised of large numbers of small, simple, and inexpensive wireless sensors, and the mobile sensor network contains a set of mobile sensors (robots). The static sensors in our network have “monitoring” ability, i.e., any activated static sensor can detect the event as long as its sensing range intersects the event region. And the mobile sensors have “moving” and “rescuing” ability, e.g., they can move toward the event region with limited speed and further perform certain rescuing/processing operations on the event. We can consider the event as a hazard, e.g., wild fire, and the mobile sensors as fireman robots. As soon as the fire is detected by the static sensors, the fireman robots are expected to move from its initial location to the hazard region within minimum latency. We define the reaction delay of the system as the delay from the occurrence of event till at least one mobile sensor reaches the event. In order to satisfy certain reaction delay requirement while minimizing the total cost, we propose a number of deployment strategies for the stationary sensor network and mobile sensor network respectively. We further design a random wake-up scheduling for the static sensors for the sake of energy efficiency. Finally, we propose a pure distributed motion strategy for mobile sensors without reliance on localization services such as GPS, focusing on simple algorithms for distributed decision making and information propagation. We demonstrate the efficacy of our system in simulation, providing empirical results.

关键词： Wireless sensor networks Large-scale systems Sensor systems Robot sensing systems Mobile robots Hazards Fires Delay systems Monitoring Event detection

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An approach to analyzing user preference based dynamic service composition

Journal of Software

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Journal of software 2010年第9期5卷 982-989页

作者： Fan, Guisheng Yu, Huiqun Chen, Liqiong Yu, Caizhu Department of Computer Science and Engineering East China University of Science and Technology Shanghai 200237 China Shanghai Key Laboratory of Computer Software Evaluating and Testing Shanghai 201112 China Department of Computer Science and Information Engineering Shanghai Institute of Technology Shanghai 200235 China

As a way to compose independent service together to fulfill a function, service composition is an important means for flexible and rapid information integration of complex distribution application in open and heterogeneous environment. However, the diversity of requirements makes it difficult to guarantee the correctness of service composition. This paper proposes a hierarchical dynamic service composition net (HDSC-net), and user's preference based mechanism for service composition. HDSC-net is used to model operation, the relationships between operations, operation mapping, and user's preference. Transfer matrix is constructed to express the relationships between states, while theories of Petri nets help prove the composability of service. The strategy for dynamic service composition and its corresponding enforcement method are also proposed. A case study of Travel Service demonstrates the applicability of proposed method and its effectiveness. © 2010 Academy Publisher.

关键词： Web services

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A protocol for bilinear parings-based attestation

A protocol for bilinear parings-based attestation

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2nd International Conference on Networks Security, Wireless Communications and Trusted Computing, NSWCTC 2010

作者： Chen, Ting Yu, Huiqun Chen, Wei Department of Computer Science and Engineering East China University of Science and Technology Shanghai 200237 China Informatization Office East China University of Political Science and Law Shanghai 201620 China Shanghai Key Laboratory of Computer Software Evaluating and Testing Shanghai 201112 China School of Mathematics and Information Shanghai Lixin University of Commerce Shanghai 201620 China

ISBN: (纸本)9780769540115

One of the objectives of trusted computing is to provide remote attestation method that is able to confirm the status of remote platform or application. Existing property-based attestation is based on the strong-RSA assumption and the required key length is too long. What's more, a considerable number of RSA-length operations having to be performed which lead to low computational efficiency. Bilinear parings-Based Attestation model, which based on elliptic curve discrete logarithm bilinear paring, can shorten the required key length and reduce bandwidth usage at the same premise of safety performance requirements, as well as ensure platform configurations not to be exposed to the platform while improving operating efficiency. On the other hand, the model includes many trusted computing platform parameters in order to resist replay attacks, and take use of information hiding technology to hide certificates and effectively preventing anyone with a source of certificate misuse of the certificate. © 2010 IEEE.

关键词： Trusted computing

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Exploiting Sink Mobility to Maximize Lifetime in 3D Underwater Sensor Networks

Exploiting Sink Mobility to Maximize Lifetime in 3D Underwat...

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IEEE International Conference on Communications (ICC)

作者： S. Shen A. Zhan P. Yang G. Chen State Key Laboratory of Novel Software Technology Nanjing University China People''s Liberation Army University of Science and Technology China Department of Computer Science Shanghai Jiaotong University China

Network lifetime is crucial to 3D Under Water Sensor Networks (UWSNs) because it decreases more seriously than in 2D scenarios as the radius of the monitored region grows. We utilize sink mobility to solve the problem intuitively because the sink deployed in a vehicle is controllable while sensors are hard to be retrieved and recharged. It is hard to extend the results in 2D scenarios, i.e., a circular motion, to 3D UWSNs directly because there are more factors influencing network lifetime. However there is little literature on utilizing and analyzing sink mobility in 3D UWSNs. To simplify 3D sink mobility, we convert any motion to a combination of circular motions through mapping. After discussing the characteristics of circular motions, we propose MOSS, an optimal MObile Sink Strategy, to maximize the network lifetime in 3D UWSNs. Simulation results show that MOSS outperforms other motion strategies and improves the network lifetime at least in the order of 800% when R ≥ 5r, where R is the network radius and r is the transmission range of sensors.

关键词： Oceans Sensor phenomena and characterization Underwater vehicles Routing Paper technology computerized monitoring Sea surface Relays Communications Society Laboratories

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Maximizing Lifetime of Sensor Surveillance Systems with Directional Sensors

Maximizing Lifetime of Sensor Surveillance Systems with Dire...

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International Conference on Mobile Ad-hoc and Sensor Networks, MSN

作者： Xiang Cao Xiaohua Jia Guihai Chen State Key Laboratory for Novel Software Technology Nanjing University Nanjing China Department of Computer Science University of Hong Kong Hong Kong China

In this paper, we address the maximal lifetime scheduling problem in sensor surveillance systems with directional sensors. The sensors are directional in sensing objects (or watching targets) and their sensing orientations can be adjusted dynamically. Given a set of sensors and a set of targets in a plane, each target needs to be watched all the time and a sensor can watch all the targets within its sensing range. The problem of our concern is to schedule the sensors to watch all the targets and transmit the sensed data to the base station, such that the lifetime of this surveillance system is maximized. The lifetime is the duration up to the time when there exists a target that cannot be watched by any sensor or the sensed data cannot be transmitted to the base station due to the depletion of energy of some sensors. This problem is NP-hard. We propose a heuristic method that divides the system lifetime into sessions and the sensors are scheduled to work in turn in these sessions. The heuristic method consists of two steps: (1) selecting sensors to work for each session, (2) scheduling the length of each session such that the total working time for all sessions is maximized. Extensive simulations have been conducted to demonstrate that our proposed method can significantly improve the lifetime of the system.

关键词： Base stations Sensors Relays Watches Linear programming Scheduling Data models

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PCAR: A power controlled routing protocol for wireless ad hoc networks

PCAR: A power controlled routing protocol for wireless ad ho...

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IEEE International Symposium on World of Wireless Mobile and Multimedia Networks (WoWMoM)

作者： Xue Zhang Ming Liu Haigang Gong Sanglu Lu Jie Wu School of Computer Science and Engineering University of Electronic Science and Technology Chengdu China State Key Laboratory of Novel Software Technology Nanjing University Nanjing China Department of Computer and Information Science Temple University Philadelphia PA USA

Power control and routing are two fundamental supporting techniques for wireless communications in ad hoc networks. However, most existing power control and routing proposals are not really efficient enough, due to separate considerations on them. In this paper, motivated by the observation on the necessity and feasibility of the combination of power control and routing, we propose a power controlled routing protocol PCAR (Power Controlled Ad hoc Routing). The basic idea is to develop power control on top of the distance-vector routing mechanism that is based on the classical distributed Bellman-Ford algorithm. Each node adjusts the transmission power automatically through the PIPC (Proportion-Integral Power Control) algorithm that we previously proposed. Both theoretical analysis and simulation results show that PCAR has a good performance.

关键词： Routing Power control Routing protocols Mobile ad hoc networks Topology Proposals

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Automatic Structured Web Databases Classification

Automatic Structured Web Databases Classification

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2010 IEEE International Conference on Intelligent Computing and Intelligent Systems(2010 IEEE 智能计算与智能系统国际会议 ICIS 2010)

作者： XiaoJun Cui ZhongSheng Ren Le Xu HongYu Xiao Wenzhou Vocational College of Science and Technology Wenzhou China State Key Laboratory of Software College of Mathematics and Computer Science Fujian Normal University Fuzhou China Department of Information and Technology Wenzhou Vocational College of Science and Technology Wenzho

The growing structured Web databases on the web, making large-scale Deep Web data integration faces enormous challenges. Organizing such structured web databases into a hierarchy directory tree is one of critical step towards the large-scale integration of Deep Web. In this paper, a method for automatic classification of Web database is addressed. Firstly, the method for calculating the semantic similarities among the Web databases based on their interface schemas is proposed and be translated to the problem of extended optimal matching for bipartite graph. Then based on the achieved similarity matrix, an agglomerative hierarchical clustering algorithm is proposed, which can organize the Web databases into a hierarchy tree automatically. Theoretical analysis and experimental results show that the method is efficient.

关键词： web databases interface schema bipartite graph matching hierarchical clustering

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k-biclusters algorithm for gene expression data

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Journal of Computational Information Systems 2010年第12期6卷 4035-4043页

作者： He, Ping Xi, Yanqiu Pan, Zhoujin Xu, Xiaohua Chen, Ling Department of Computer Science and Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China Department of Computer Science Yangzhou University Yangzhou 225009 China State Key Laboratory for Novel Software Technology Nanjing University Nanjing 210093 China

In this paper, we propose a k-means algorithm which aims to find k biclusters for given gene expression data. Our algorithm k-Biclusters first clusters the columns (conditions) and groups the row (genes) in each subset of columns, then applies the row-clustering and column-clustering methods iteratively until the "steady" biclusters are found. After that, we refine the "steady" biclusters by reducing their Hscores and maximize the cluster size in the end. Experimental results demonstrate that the algorithm can efficiently find the co-regulation patterns, especially those highly homogenous with little difference from each other. © 2010 Binary Information Press.

关键词： Iterative methods

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DAWN: Energy efficient data aggregation in WSN with mobile sinks

DAWN: Energy efficient data aggregation in WSN with mobile s...

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International Workshop on Quality of Service

作者： ShaoJie Tang Jing Yuan XiangYang Li Yunhao Liu GuiHai Chen Ming Gu JiZhong Zhao Guojun Dai Department of Computer Science Illinois Institute of Technology Chicago IL USA State Key Laboratory of Novel Software Technology NanJing University NanJing China Institute of Computer Application Technology Hangzhou Dianzi University China Department of Computer Science and Engineering HKUST China Key Laboratory of Information System Security Tsinghua University China Department of Computer Science and Engineering Xi'An JiaoTong University China

The benefits of using mobile sink to prolong sensor network lifetime have been well recognized. However, few provably theoretical results remain are developed due to the complexity caused by time-dependent network topology. In this work, we investigate the optimum routing strategy for the static sensor network. We further propose a number of motion stratifies for the mobile sink(s) to gather real time data from static sensor network, with the objective to maximize the network lifetime. Specially, we consider a more realistic model where the moving speed and path for mobile sinks are constrained. Our extensive experiments show that our scheme can significantly prolong entire network lifetime and reduce delivery delay.

关键词： Energy efficiency Wireless sensor networks Routing computer science Optical sensors Temperature sensors Laboratories Data engineering Power engineering and energy Network topology

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