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Location based spectrum sensing performance analysis over fading channels in cognitive radio networks

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The Journal of china Universities of Posts and Telecommunications 2010年第5期17卷 26-31页

作者： YAO Hai-peng,ZHOU Zheng,SUN Xuan,LI Bin School of information and Communication engineering,beijing university of Posts and Telecommunications,beijing 100876,china School of information and Communication engineering Beijing University of Posts and Telecommunications Beijing 100876 China

This paper analyzes the spectrum sensing performance over fading channel,in which a licensee and multiple unlicensed users coexist and operate in the licensed channel in a local *** overall average probabilities of detection and false alarm by jointly taking the fading and the locations of all secondary users into account are derived,and a statistical model of cumulate interference is *** on the cumulate interference,a closed-form expression of outage probability at the primary user’s receiver according to a specific distribution of the fading is ***,the sensing parameters so as to minimize the total spectrum sensing error and maximize the average opportunistic throughput are *** is noted that the overall average performance analysis and results here enable to benchmark the design of specific spectrum sensing algorithms.

关键词： spectrum sensing cognitive radio cumulate interference outage probability

Image-based modeling of inhomogeneous single-scattering participating media

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Science china(information Sciences) 2010年第6期53卷 1141-1150页

作者： HU Yong 1 , QI Yue 1 & TONG Xin 2 1 State Key Laboratory of Virtual Reality Technology and Systems, beihang university, beijing 100191, china 2 Microsoft Research Asia, beijing 100080, china State Key Laboratory of Virtual Reality Technology and Systems Beihang University Beijing China Microsoft Research Asia Beijing China

We propose a method to reconstruct inhomogeneous single-scattering participating media, which could preserve fine high-frequency details of density *** data and the ratio of absorption coefficient to scattering coefficient are used to describe the spatial-varying density distribution and optical properties of certain participating media, and a function between the above parameters and captured pixel values is *** the problem of how to find solutions to these parameters is formulated into a nonlinear numerical optimization *** order to reduce large time overheads and numerical instability brought by simultaneously solving large numbers of voxels, we propose an initialization algorithm for enabling the assigned density values to satisfy the regularity of brightness distribution in captured images approximately as well as a progressive refinement algorithm for multi-resolution volumetric ***, we propose a parallel multi-voxel gradient computation algorithm of utilizing hardware acceleration to reduce time overheads in gradient computation for large numbers of *** results indicate that our method is well suited for reconstructing thin smoke, retaining high-frequency details from images captured from multiple viewpoints.

关键词： single-scattering participating media smoke modeling volumetric modeling image based modeling

Pointwise estimates for the maximal multilinear singular integral operators

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Science china Mathematics 2005年第12期48卷 1696-1706页

作者： HU Guo’en, LI Dengfeng & LU Shanzhen Department of Applied Mathematics, university of information engineering, P. O. Box 1001 -747, Zhengzhou 450002, china College of Mathematical and information Sciences, Henan university, Kaifeng 475001, china Department of Mathematics, beijing Normal university, beijing 100875, china Department of Applied Mathematics University of Information Engineering Zhengzhou 450002 China College of Mathematical and information Sciences Henan University Kaifeng 475001 China Department of Mathematics Beijing Normal University Beijing 100875 China

Two pointwise estimates relating the maximal multilinear singular integral operators and some classical maximal operators are established. These pointwise estimates imply the rearrangement estimate and the BLO(Rn) est... 详细信息

关键词： multilinear singular integral,maximal operator,BMO (Rn),BLO (Rn).

A rate based congestion control algorithm in networks with coexisting unicast and multicast sessions

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Journal of university of Science and Technology beijing 2003年第3期10卷 66-72页

作者： Qian Dong and Jianying XieSchool of electronics & information Technology, Shanghai Jiaotong university, Shanghai 200030, china Sch. of Electron. and Info. Technol. Shanghai Jiaotong Univ. Shanghai 200030 China

The optimal rate control problem in networks with unicast and multiratemulticast sessions is investigated. A penalty function approach is used to solve a convex programformulation of this problem, and then a heuristic rate control algorithm is derived. The algorithmis distributed, and suitable both for source-driven unicast sessions and receiver-driven multicastsessions. To obtain practical viability, the computational burden on core routers as well asend-hosts is kept very low, also is the overhead of network congestion feedback. Simulation resultsshow that the algorithm guarantees TCP (Transmission Control Protocol)-based unicast sessionscoexisting with multirate multicast sessions in a fair and friendly manner. It is also shown thatvarious fairness criteria of resource allocation could be achieved by choosing appropriate utilityfunctions, and resource-utilizing efficiencies would be likewise different.

关键词： multicast unicast congestion control rate control fairness

Application of intelligent control theory in AC servo system

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International Journal of Minerals,Metallurgy and Materials 1997年第3期11卷 43-45页

作者： WANG Zhiliang XIE Lun IJ Chongjian (information engineering School, university of Science and Technology beijing, beijing 100083, china) (Automation Research institute of Metallurgical Industry, beijing 100071, china) Univ of Science and Technology Beijing Beijing China

An AC servo system based on neuron control theory is presented. Experimental results show that the neuralcontrol mode doesn't need the Precise model of the system, therefore, it has many advantages, such as simple designand high response performance. The simulation research of the AC servo system which is non-linear, *** on neuro-fuzzy controller is done. The results of the simulation show that the performances of the system areconsiderably improved and it is one of the novel pathways to realize intelligent control of servo system.

关键词： servo system fuzzy control neural networks neuro-fuzzy networks

Optimized statistical analysis of software trustworthiness attributes

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Science china(information Sciences) 2012年第11期55卷 2508-2520页

作者： ZHANG Xiao1,LI Wei2,ZHENG ZhiMing1,2 & GUO BingHui1 1Key Laboratory of Mathematics,Informatics and Behavioral Semantics,Ministry of Education,beihang university,beijing 100191,china 2State Key Laboratory of Software Development Environment,beihang university,beijing 100191,china Key Laboratory of Mathematics Informatics and Behavioral Semantics Ministry of Education Beihang University Beijing China State Key Laboratory of Software Development Environment Beihang University Beijing China

Software trustworthiness has become one of the key restrictions for software service quality and the development of the software ***,trustworthiness attributes interlace structured and dynamical coupling relations,which causes great barriers for trustworthiness measurements of large-scale *** to the dynamical evolutionary characteristics of software trustworthiness attributes,this paper proposes a new approach for optimizing the trustworthiness measurement in terms the kernel trustworthiness attributes,and improves a downsize-optimized statistical analysis method for software trustworthiness attributes based on their nonlinear *** improved method considerably simplifies the trustworthiness assessment of largescale *** theoretical analysis and numerical simulations,the feasibility of this method is verified using two typical examples that illustrate the realization of the trustworthiness measurement.

关键词： software trustworthiness kernel attributes optimization statistical analysis

Network layered priority mapping theory

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Science china(information Sciences) 2010年第9期53卷 1713-1726页

作者： YANG Dong*,ZHANG HongKe,SONG Fei&LI ShiYong National engineering Laboratory for Next Generation Internet Interconnection Devices, School of electronics and information engineering,beijing Jiaotong university,beijing 100044,china National engineering Laboratory for Next Generation Internet Interconnection Devices School of Electronics and Information Engineering Beijing Jiaotong University Beijing China

In the early days of the Internet layered design,the information between layers did not exchange in large amount *** the rapid growth of the Internet,the emergence of many technologies such as service data partition,multi-connection and multi-path has made it possible to frequently exchange complex information between *** regard to these changes,this paper introduces "network layered priority mapping(NLPM)" for future Internet *** NLPM aims to maximize the satisfaction of the Internet *** NLPM is designed to differentiate priority of the information on different layers and integrate the information using priority *** NLPM,network services can be delivered more efficiently;network utilization such as the utilization of connection,path and channel can also be *** analysis,NS simulation and prototype implementation have proved the efficiency of NLPM.

关键词： future Internet layered priority mapping

Efficient visualization techniques for high resolution remotely sensed data in a network environment

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Science china(Technological Sciences) 2008年第S1期51卷 124-134页

作者： WENG JingNong1,WU Lun2,HUANG Jian1,XIA YuBin3 & CAI Heng1 1 College of Software,beihang university,beijing 100083,china 2 Institute of Geographical information System and Remote Sensing,Peking university,beijing 100871,china 3 College of Computer,beihang university,beijing 100083,china College of Software Beihang University Beijing China Institute of Geographical information System and Remote Sensing Peking University Beijing China College of Computer Beihang University Beijing China

There are three major research hotspots in efficient visualization techniques of high resolution remotely sensed data in network environment: the data organiza-tion and access in disk storage,the image data stitching and fitting methods,and the network transfers and access. In this paper a new method of "Big File" organi-zation for improving the storage access efficiency of high resolution remote data is presented; a "virtual data source" concept is introduced to solve the stitching problem of remotely sensed data from different sources with different resolutions; a remotely sensed data access engine design based on ATL technique is discussed to process the network transfers and access of remotely sensed data. All these techniques have been adopted in a prototype of digital china named "chinaStar".

关键词： high resolution remotely sensed data spatial index pyramid model LOD Big File

基于空时聚焦传输的多源单中继超宽带网络传输性能分析

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通信学报 2012年第3期33卷 20-27页

作者：田亚飞杨晨阳北京航空航天大学电子信息工程学院北京100191

超宽带空时聚焦传输降低了多用户传输时的互相干扰,可以让多个源节点和多个目的节点通过一个中继节点进行通信。研究了基于空时聚焦传输的多源单中继超宽带网络的传输性能,分别推导了多址阶段和广播阶段的中断概率,得到了网络吞吐量与... 详细信息

超宽带空时聚焦传输降低了多用户传输时的互相干扰,可以让多个源节点和多个目的节点通过一个中继节点进行通信。研究了基于空时聚焦传输的多源单中继超宽带网络的传输性能,分别推导了多址阶段和广播阶段的中断概率,得到了网络吞吐量与用户数目、节点距离、超宽带脉冲宽度、信号帧周期、接收信干噪比等参数之间的解析关系,并通过最大化网络吞吐量以及优化结果分析得到了传输方案的设计准则。最后,仿真结果验证了不同路径损耗因子下2个阶段的中断概率。

关键词：超宽带通信空时聚焦协作中继