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P2P traffic optimization

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Science china(Information Sciences) 2012年第7期55卷 1475-1492页

作者： ZHANG GuoQiang 1,2 ,TANG MingDong 3 ,CHENG SuQi 2,4 ,ZHANG GuoQing 2 ,SONG HaiBin 5 ,CAO JiGuang 6 & YANG Jing 7 1 School of computer Science and technology,Nanjing Normal University,Nanjing 210046,china 2 institute of Computing technology,Chinese Academy of Sciences,beijing 100190,china 3 School of computer Science and Engineering,Hunan University of Science and technology,Xiangtan 411201,china 4 Graduate University of Chinese Academy of Sciences,beijing 100190,china 5 Nanjing R&D center,Huawei Technologies,Nanjing 210012,china 6 china Academy of Telecommunication Research of MIIT,beijing 100191,china 7 china Mobile Research institute,beijing 100053,china 1. School of computer Science and technology Nanjing Normal University Nanjing 210046 China2. Institute of Computing Technology Chinese Academy of Sciences Beijing 100190 China3. School of Computer Science and Engineering Hunan University of Science and Technology Xiangtan 411201 China4. Graduate University of Chinese Academy of Sciences Beijing 100190 China5. Nanjing R&D Center Huawei Technologies Nanjing 210012 China6. China Academy of Telecommunication Research of MIIT Beijing 100191 China7. China Mobile Research Institute Beijing 100053 China

Peer-to-peer (P2P) based content distribution systems have emerged as the main form for content distribution on the Internet,which can greatly reduce the distribution cost of content providers and improve the overall system ***,the mismatch between the overlay and underlay networks causes large volume of redundant traffic,which intensifies the tension between P2P content providers and ***,how to efficiently use network resources to reduce the traffic burden on the ISPs is crucial for the sustainable development of P2P *** paper surveys the state-of-art P2P traffic optimization technologies from three perspectives:P2P cache,locality-awareness and data *** details,comparison between these technologies and their applicabilities are presented,followed by a discussion of the issues that remain to be addressed and the direction of future content distribution research.

关键词： P2P traffic localization P2P traffic optimization P2P cache locality-awareness network coding content-centric network

Spatio-temporal pattern analysis of single-trial EEG signals recorded during visual object recognition

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Science china(Information Sciences) 2011年第12期54卷 2519-2527页

作者： WANG ChangMing 1 , HU XiaoPing 3 , YAO Li 1,2 , XIONG Shi 2 & ZHANG JiaCai 2 1 National Key Laboratory of Cognitive Neuroscience and Learning, beijing Normal University, beijing 100875, china 2 College of Information Science and technology, beijing Normal University, beijing 100875, china 3 Biomedical Imaging technology center, Emory University/Georgia institute of technology, Atlanta 30322, USA 1. National Key Laboratory of Cognitive Neuroscience and Learning Beijing Normal University Beijing 100875 China3. Biomedical Imaging Technology Center Emory University/Georgia Institute of Technology Atlanta 30322 USA2. College of Information Science and Technology Beijing Normal University Beijing 100875 China

Object discrimination is a fundamental cognitive function for human brains. In this study, we utilized an analysis approach for single-trial electroencephalography (EEG) to analyze the spatio-temporal activation patterns of visual objects processing in human brains, and attempted to apply it to discriminate different visual objects. The spatial patterns were respectively extracted from scalp EEG and the reconstructed cortical sources, while the experiment participants were perceiving 4 different categories of visual objects (faces, buildings, cats and cars). By classifying the patterns extracted from single-trial EEG, the presented visual objects could be discriminated by a computer, and the classification accuracies may provide a quantitative index to evaluate the spatial differences of the brain activations related to different visual objects. Our results demonstrated that the spatial patterns on both the scalp and the sources levels resulted in higher classification accuracies than chance rate. We also examined the classification results using temporally non-overlapping time intervals of different event-related potential (ERP) components. The temporal changes of classification accuracies may reflect the temporal distribution of the discriminative information in the EEG responses. The present pattern extraction and classification methods may compose a computational model for single-trial EEG data analysis in investigations of the spatio-temporal activation patterns for object recognition. These spatio-temporal patterns in EEG may be useful to identifying the discriminative spatial areas and time stages to improve the accuracies and efficiencies of object discrimination. In addition, investigating and utilizing humans'cognitive mechanisms of object recognition may improve computers' processing efficiency of visual information.

关键词： EEG spatio-temporal pattern object recognition single-trial analysis visual information processing

Radar Imaging Based on Iterative Algorithms

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Journal of Systems Engineering and Electronics 1991年第2期2卷 91-99页

作者： Qiangfu Zhao, Zhong Wang and Youan KeDept. of Electronic Eng., beijing institute of technology, P.O.Box 327, beijing 100081, china Dept. of Electronic Eng. Beijing Institute of Technology P.O. Box 327 Beijing 100081 China

It has long been realized that the problem of radar imaging is a special case of image reconstruction in which the data are incomplete and noisy. In other fields, iterative reconstruction algorithms have been used successfully to improve the image quality. This paper studies the application of iterative algorithms in radar imaging. A discrete model is first derived, and the iterative algorithms are then adapted to radar imaging. Although such algorithms are usually time consuming, this paper shows that, if the algorithms are appropriately simplified, it is possible to realize them even in real time. The efficiency of iterative algorithms is shown through computer simulations.

关键词： Radar imaging computerized tomography Discrete model Iterative reconstruction algorithm Algebraic reconstruction technique.

Semantic Session Analysis for Web Usage Mining

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Wuhan University Journal of Natural Sciences 2007年第5期12卷 773-776页

作者： ZHANG Hui SONG Hantao XU Xiaomei Department of computer Science and Engineering Beijing Institute of Technology Beijing 100081 China

A semantic session analysis method partitioning Web usage logs is presented. Semantic Web usage log preparation model enhances usage logs with semantic. The Markov chain model based on ontology semantic measurement is used to identifying which active session a request should belong to. The competitive method is applied to determine the end of the sessions. Compared with other algorithms, more successful sessions are additionally detected by semantic outlier analysis.

关键词： Web usage mining Web log preparation session analysis

Concatenating construction of the multisymplectic schemes for 2+1-dimensional sine-Gordon equation

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Science china Mathematics 2004年第1期47卷 18-30页

作者： WANG Yushun, WANG Bin & QIN MengzhaoLASG, institute of Atmospheric Physics, Chinese Academy of Sciences, beijing 100029, china School of Mathematics and computer Science, Nanjing Normal University, Nanjing 210097, china School of Mathematics and System Science, Chinese Academy of Sciences, beijing 100080, china 1. LASG Institute of Atmospheric Physics Chinese Academy of Sciences 100029 Beijing China 2. School of Mathematics and computer Science Nanjing Normal University 210097 Nanjing China 3. School of Mathematics and System Science Chinese Academy of Sciences 100080 Beijing China

In this paper, taking the 2+1-dimensional sine-Gordon equation as an example, we present the concatenating method to construct the multisymplectic schemes. The method is to discretizee independently the PDEs in different directions with symplectic schemes, so that the multisymplectic schemes can be constructed by concatenating those symplectic schemes. By this method, we can construct multisymplectic schemes, including some widely used schemes with an accuracy of any order. The numerical simulation on the collisions of solitons are also proposed to illustrate the efficiency of the multisymplectic schemes.

关键词： 2+l-climensional sine-Gordon equation multisymplectic scheme concatenating method solitons

INVESTIGATION OF THE EFFECT OF TEMPERATURES ONTENSILE LOAD DROPS OF TITANIUM ALLOY

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Acta Metallurgica Sinica(English Letters) 1997年第3期10卷 198-202页

作者： Z Zhang ZH Tu L.F. Li L.Z. Zhaoand D. Jin (Cryogenic Laboratory Chinese Acaderw of Sciences, beijing 100080, china )H.J Lu (beijing institute of Aerospace Materials and technology, beijing 100076, china) Cryogenic Lab Chinese Acad of Sciences Beijing China

Low temperature may greatly affect the mechanical properties of materials. Some in-teresting mechanical phenomena were detected at very low temperature. In this study,a multi-sample tensile installation was designed to study the plastic deformation be-havior for Ti-5Al-2.5Sn extra-low-interstitial (ELI) alloy at liquid helium *** special geometrical instability phenomena in low temperature, serrated deforma-tion and multi necking, was studied in detail in this project. Slip and twinning were determined in the process of plastic fiow by SEM/TEM analysis. Efficts of temper-ature and sequential straining on load drops in tensile stress-strain curves were also studied. Optical measurement method was used to gauge the geometrical characteristic of multi-necking specimens. The sensitivity of partial thermoplastic deformation and the equivalency of low tempemture with high velocity of this material were studied by using micro-mechanics *** criterion of geometrical instability has been discussed. A computer simulation of the low temperature instability of plastic fiow in Ti-5Al-2.5Sn ELI alloy has been carried out. A computer model has been established which links the hot dtffusion and the plastic fiow of hcp alloys under assumption that the tempemture is homogeneous within the specimen and that the heat exchange with the thermal bath is the control-ling step in the heat release. The computer simulation of the deformation curves as a function of several mechanincal, geometrical and thermal parameters provides a re-alistic description of the experiments. The experimental data available are discnssed in the light of the computer simulation model.

关键词： mechanical property plastic deformation computer simulation

3D building modeling,organization and application in digital city system

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中国科学：技术科学英文版 2010年第S1期53卷 134-142页

作者： YANG Xue 1,WENG JingNong 1,2,XIA YuBin 2,WU Lun 3 & SUI ZhengWei 3 1 College of Software,Beihang University,beijing 100191,china 2 College of computer,Beihang University,beijing 100191,china 3 institute of Remote Sensing and GIS,Peking University,beijing 100871,china Beihang Univ Coll Software Beijing 100191 Peoples R China Beihang Univ Coll Comp Beijing 100191 Peoples R China Peking Univ Inst Remote Sensing & GIS Beijing 100871 Peoples R China

The real world is a three-dimensional(3D)space requiring that 3D geospatial information applications be developed in alignment with the observer’s visual and perceptive ***,3D building model data are required in a wide range of areas such as urban planning,environmental protection,real estate management and emergency *** the same time,the development of Web service[LU1]technologies allows the possibility of the widely distributed 3D geospatial data on the web.3D city building model with its related information is an important part in the construction of a digital city system,and has become a staple resource on the web *** view of the hierarchical representation of a 3D building model,an abstract of a 3D building model based on structure details is studied,and a novel representation approach named 3D transparent building hierarchical model is presented in this *** approach fully uses both the existing 3D modeling technologies and CAD constructing mapping *** the spatial relationship description,structural components inside a building can be represented and integrated as hierarchical models in a unified 3D *** addition,based on the characteristics of the 3D building model data,a service-oriented architecture and Web service technologies for 3D city building models are *** aim of the approach is that 3D city building models can be used as a kind of data resource service on the web,and can also exist independently in various different web applications.

关键词： 3D modeling 3D transparent building hierarchical models china Star web services

Concrete Physics Method for Solving NP hard Problem

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Wuhan University Journal of Natural Sciences 2001年第Z1期6卷 140-146页

作者： Huang Wen\|qi College of computer Science, Huazhong University of Science and technology, Wuhan 430074,china Laboratory of computer Science, institute of Software, Chinese Academy of Sciences, beijing 100080, china College of computer Science Huazhong University of Science and Technology Wuhan China Laboratory of computer Science Institute of Software Chinese Academy of Sciences Beijing China

With a NP hard problem given, we may find a equivalent physical world. The rule of the changing of the physical states is simply the algorithm for solving the original NP hard problem .It is the most natural algorithm for solving NP hard problems. In this paper we deal with a famous example , the well known NP hard problem——Circles Packing. It shows that our algorithm is dramatically very efficient. We are inspired that, the concrete physics algorithm will always be very efficient for NP hard problem.

关键词： concrete physics algorithm NP hard problem circles packing the rule of the changing of the physical states

A New Method of Structuring the Hierarchy of a System

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Journal of Systems Engineering and Electronics 1991年第2期2卷 27-33页

作者： Zhou Shipengbeijing Research institute of Engineering technology, beijing 100012, china beijing Research institute of Engineering technology. beijing 100012 China

Structuring the hierarchy of a system is an important link of solving problems with the analytic hierarchy process. This paper gives and proves the two theorems about the relationship between the hierarchy and the reachability matrix of the system. On the basis of it, we propose a method of structuring hierarchy by directly using the reachability matrix of the system. This method is simpler and clearer than that of interpretive structural modeling and is suitable for both manual calculating and computer proceeding. It fully shows the simplicity of the AHP.

关键词： Analytic hierarchy process Hierarchy Reachability matrix.