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l-SkyDiv query:Effectively improve the usefulness of skylines

science China(information sciences) 2010年第9期53卷 1785-1799页

作者： HUANG ZhenHua1,2*,XIANG Yang1 & LIN ZiYu3 1department of computer science and technology,Tongji University,Shanghai 201804,China 2The key laboratory of Embedded system and Service Computing,Ministry of Education,Tongji University,Shanghai 200092,China 3department of computer science and technology,Peking University,Beijing 100871,China 1. Department of Computer Science and Technology Tongji University Shanghai 201804 China2. The Key Laboratory of Embedded System and Service Computing Ministry of Education Tongji University Shanghai 200092 China3. Department of Computer Science and Technology Peking University Beijing 100871 China

Skyline query processing has recently received a lot of attention in database *** a set of multi-dimensional objects,the skyline query finds the objects that are not dominated by *** the best of our knowledge,the existing researches mainly focus on how to efficiently return the whole skyline ***,as the cardinality and dimensionality of input dataset increase,the number of skylines grows exponentially,and hence this "huge" skyline set is completely useless to *** by the above fact,in this paper,we present a novel type of l-SkyDiv query,which only returns l skylines having maximum diversity,to improve the usefulness of skyline ***,we prove that the l-SkyDiv query belongs to the NP-Hard problem theoretically,and propose three efficient heuristic algorithms whose time complexities are polynomial to fast implement the proposed ***,we present detailed theoretical analyses and extensive experiments,demonstrating that our algorithms are both efficient and effective.

关键词： skyline query diversity heuristic algorithm query optimization performance evaluation

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Factor analysis and majority voting based speech emotion recogntion

Factor analysis and majority voting based speech emotion rec...

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International Conference on Intelligent system Design and Engineering Application (ISDEA)

作者： Xu, Lu Xu, Mingxing Yang, Dali State Key Laboratory of Intelligent Technology and Systems Department of Computer Science and Technology Tsinghua University Beijing 100084 China Department of Computer Science and Technology Beijing Information Science and Technology University Beijing 100101 China

ISBN: (纸本)9780769542126

There are some problems to be resolved for speech emotion recognition, such as the dimension of feature sets is usually too high and the redundancy among various features is relatively stronger. Considering these problems, the factor analysis and majority voting based speech emotion recognition was proposed. How to extract emotional factors from global statistical features and GMM supervectors was researched. Several classifiers were adopted to perform the majority voting based decision fusion. Experimental results demonstrated that factor scores are stronger correlated with emotional states and the majority voting based method effectively enhanced the cohesion of training data. © 2010 IEEE.

关键词： Factor analysis

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Multicast capacity scaling for cognitive networks: General extended primary network

Multicast capacity scaling for cognitive networks: General e...

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2010 IEEE 7th International Conference on Mobile Adhoc and Sensor systems, MASS 2010

作者： Wang, Cheng Li, Xiang-Yang Tang, Shaojie Jiang, Changjun Department of Computer Science Tongji University Shanghai China Key Laboratory of Embedded System and Service Computing Ministry of Education Shanghai China Tsinghua National Laboratory for Information Science and Technology Tsinghua University Beijing China Department of Computer Science Illinois Institute of Technology Chicago IL 60616 United States

ISBN: (纸本)9781424474882

We study the capacity scaling laws for the cognitive network that consists of the primary hybrid network (PhN) and secondary ad hoc network (SaN). PhN is further comprised of an ad hoc network and a base station based (BS-based) network. SaN and PhN are overlapping in the same deployment region, operate on the same spectrum, but are independent with each other in terms of communication requirements. The primary users (PUs), i.e., the ad hoc nodes in PhN, have the priority to access the spectrum. The secondary users (SUs), i.e., the ad hoc nodes in SaN, are equipped with cognitive radios, and have the functionalities to sense the idle spectrum and obtain the necessary information of primary nodes in PhN. We assume that PhN adopts one out of three classical types of strategies, i.e., pure ad hoc strategy, BS-based strategy, and hybrid strategy. We aim to directly derive multicast capacity for SaN to unify the unicast and broadcast capacity under two basic principles: (1) The throughput for PhN cannot be undermined in order sense due to the presence of SaN. (2) The protocol adopted by PhN does not alter in the interest of SaN, anyway. Depending on which type of strategy is adopted in PhN, we design the optimal-throughput strategy for SaN. We show that there exists a threshold of the density of SUs according to the density of PUs beyond which it can be proven that: (1) when PhN adopts the pure ad hoc strategy or hybrid strategy, SaN can achieve the multicast capacity of the same order as it is stand-alone;(2) when PhN adopts the BS-based strategy, SaN can asymptotically achieve the multicast capacity of the same order as if PhN were absent, if some conditions of the relations among the number of SUs, PUs, the destinations of each multicast sessions in SaN, and the base stations in PhN hold. ©2010 IEEE.

关键词： Base stations

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Filling n-sided regions with G1 triangular Coons B-spline patches

Filling n-sided regions with G1 triangular Coons B-spline pa...

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作者： Shi, Kan-Le Yong, Jun-Hai Sun, Jia-Guang Paul, Jean-Claude Gu, He-Jin School of Software Tsinghua University Beijing 100084 China Department of Computer Science and Technology Tsinghua University Beijing 100084 China Key Laboratory for Information System Security Ministry of Education of China Beijing 100084 China Tsinghua National Laboratory for Information Science and Technology Beijing 100084 China INRIA Nancy France Jiangxi Academy of Sciences Nanchang 330029 China

Filling n-sided regions is an essential operation in shape and surface modeling. Positional and tangential continuities are highly required in designing and manufacturing. We propose a method for filling n-sided regions with untrimmed triangular Coons B-spline patches, preserving G1 continuity exactly. The algorithm first computes a central point, a central normal, the central, and the corner derivative vectors. Then the region is split into n triangular areas by connecting the central point to each corner of the boundary. These inner curves and all cross-boundary derivatives are computed fulfilling G1 compatibility conditions. And finally, the triangular patches are generated in the Coons B-spline form, one boundary of which is regressed to the central vertex. Neither positional nor tangential error is introduced by this method. And only one degree elevation is needed. © Springer-Verlag 2010.

关键词： Filling

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Multi-image based photon tracing for interactive global illumination of dynamic scenes

Multi-image based photon tracing for interactive global illu...

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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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Refinement checking for interface automata with Z notation

Refinement checking for interface automata with Z notation

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作者： Cao, Zining National Key Laboratory of Science and Technology on Avionics System Integration Shanghai 200233 China Department of Computer Science and Technology Nanjing University of Aero. and Astro. Nanjing 210016 China Provincial Key Laboratory for Computer Information Processing Technology Soochow University Suzhou 215006 China

In this paper, we first introduce a specification approach combining interface automata and Z language, which is named ZIA. A refinement relation on ZIAs is proposed. We then give an algorithm for checking refinement ... 详细信息

ISBN: (纸本)1891706268

关键词： Automata theory

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A new subjective trust model in grid computing

A new subjective trust model in grid computing

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International Conference on computer Application and system Modeling

作者： Huang, Hai-Sheng Wang, Ru-Chuan School of Computer Science and Technology Nanjing University of Posts and Telecommunications Nanjing 210003 China State Key Laboratory of Information Security Graduate School of Chinese Academy of Science Beijing 100039 China Department of Mathematics and Computer Chizhou University Chizhou Anhui 247000 China

According to character of grid computing, the subjective trust model is proposed. It discriminates the trust relationships between entities in the same domain and in different domains and handles the two different tru... 详细信息

ISBN: (纸本)9781424472369

关键词： Grid computing

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Availability based trust model of clusters for MANET

Availability based trust model of clusters for MANET

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7th International Conference on Service systems and Service Management, ICSSSM'10

作者： Zhao, Xibin You, Zhiyang Zhao, Zhifeng Chen, Danning Peng, Feng Key Laboratory for Information System Security of Ministry of Education School of Software Tsinghua University 100084 China Department of Computer Science and Technology Tsinghua University 100084 China Department of Computer Science Zhenjiang Watercraft College 212003 China School of Software Tsinghua University 100084 China China Minzu Securities Co. Ltd. 100096 China

ISBN: (纸本)9781424464876

MANET (Mobile ad hoc network) is vulnerable to security attack due to its characteristics such as open network environment, lack of centralized control, dynamic topology, and so on, while traditional security mechanisms cannot meet the security requirements of MANET due to the limited communication bandwidth, computation power, memory and battery capacity, and dynamic deployment environment. Many approaches have been suggested to trade-off between the security strength and efficiency, and most of them focus on the confidentiality and integrity of MANET while pay less attention to the availability issue. Based on the analysis of availability related factors in MANET, we present an availability based trust model in this paper. Furthermore, a cluster based trust model (ABTMC, Availability Based Trust Model of Clusters) is presented with the consideration with the resource constrain of node, dynamic topology, and the unbalance of computing capability and resource capability among MANET nodes. Many availability oriented security service can be obtained based on this model. ©2010 IEEE.

关键词： Availability

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Compositional abstraction refinement for timed systems

Compositional abstraction refinement for timed systems

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2010 4th International Symposium on Theoretical Aspects of Software Engineering, TASE 2010

作者： He, Fei Zhu, He Hung, William N. N. Song, Xiaoyu Gu, Ming School of Software Tsinghua University Beijing China Tsinghua National Laboratory for Information Science and Technology China Key Laboratory for Information System Security MOE China Synopsys Inc. Mountain View CA United States Department of ECE Portland State University Portland OR United States

ISBN: (纸本)9780769541488

Model checking suffers from the state explosion problem. Compositional abstraction and abstraction refinement have been investigated in many areas to address this problem. This paper considers the compositional model checking for timed systems. We present an automated approach which combines compositional abstraction and counter-example guided abstraction refinement (CEGAR). The proposed approach exploits the semantics of a timed automaton to procure its over-approximative abstraction. Any safety property which holds on the abstraction is guaranteed to hold on the concrete model. In the case of a spurious counter-example, our proposed approach refines and strengthens the abstraction in a component-wise method. We implemented our method with the model checking tool Uppaal. Experimental results show promising improvements. © 2010 IEEE .

关键词： Model checking

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Distributed fault detection for wireless sensor based on weighted average

Distributed fault detection for wireless sensor based on wei...

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

作者： Ji, Sai Yuan, Shen-Fang Ma, Ting-Huai Tan, Chang Aeronautic Science Key Laboratory for Smart Materials and Structures Nanjing University of Aeronautics and Astronautics Nanjing China Department of Computer Science and Technology Nanjing University of Information Science and Technology Nanjing China

ISBN: (纸本)9780769540115

This paper presents a distributed fault detection algorithm for wireless sensor networks (WSNs) by exploring the weighted average value scheme. Considering the spatial correlations in WSNs, a faulty sensor can diagnose itself through comparing its own sensed data with the average of neighbors' data. Simulation results show that sensor nodes with permanent faults are identified with high accuracy for a wide range of fault rate, and keep false alarm rate for different levels of sensor fault model. © 2010 IEEE.

关键词： Fault detection

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