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Inferring playback rate and rate resets of P2P video streaming transmissions by piecewise line envelope approximation

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The Journal of china Universities of Posts and Telecommunications 2009年第2期16卷 58-62,79页

作者： LI Chun-xi CHEN Chang-jia school of electronics and information engineering,beijing Jiaotong university,beijing 100044,china school of electronics and information engineering Beijing Jiaotong University Beijing 100044 China

Conventionally, P2P video is regarded as CBR traffic. However, our measurements have shown that the rate reset cannot be neglected in a practical IPTV system because each rate reset often leads to performance degradation. Thus, addressing the problem of inferring playback rate and rate reset in a P2P video system is significant. In this article, an algorithm termed piecewise linear envelope approximation （PLEA） is proposed, in which a follow-up time is introduced to smooth rate fluctuations in a small time scale and to adapt rate jumps in a large time scale automatically. With the PLEA algorithm, discontinuity introduced by blind segmentations adopted by current methods is avoided. Furthermore, unlike existing algorithms in which both segmentation and combinations are performed in multiple runs, only a single computation path is involved in the PLEA algorithm. This makes PLEA algorithm amenable to implementation of low complexity by either software or hardware. Both theoretical analysis and experiment based on measured data show that the PLEA outperforms existing algorithms based on segmentation.

关键词： P2P video playback rate rate reset convex hull linear program

Large field of view computed laminography with the asymmetric rotational scanning geometry

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Science china(Technological Sciences) 2010年第8期53卷 2261-2271页

作者： FU Jian 1,2 ,JIANG BaiHong&LI Bin 1 school of Mechanical engineering and Automation,beihang university,beijing 100191,china 2 Research Center of Digital Radiation Imaging and Biomedical Imaging,beihang university,beijing 100191,china school of Mechanical engineering and Automation Beihang University Beijing China Research Center of Digital Radiation Imaging and Biomedical Imaging Beihang University Beijing China

X-ray computed laminography(CL)is used in the fields of industrial inspection and medical *** can provide the internal structure three-dimensional(3D)information of a region of the objects *** is important to the clinical diagnosis and the quality control of flat objects like printed circuit boards,aircraft wings and satellite solar *** the restriction that the imaging region must be within the X-ray beam formed by the X-ray source and the detector,the imaging field of view of CL is limited by the size of detector.A new CL method with an asymmetric rotational cone-beam scanning geometry,called large field of view CL,is presented to overcome the existing *** can extend the imaging region when the imaging spatial resolution keeps the same as that of the conventional *** can also improve the imaging spatial resolution when the imaging region keeps the same as that of the conventional *** asymmetric configuration can be achieved by offsetting the detector from the conventional symmetric *** does not,however,require new detectors and X-ray source nor alter the scanning mechanical *** filtered back-projection(FBP)reconstruction algorithm and the data truncation smoothing functions have been deduced to reconstruct the images directly from the data acquired with this asymmetric *** performed numerical studies and experiments to demonstrate and validate the proposed approach. Results in these studies and experiments confirm that the proposed method can enlarge the imaging region and improve the spatial *** proposed approach may find applications in the CL system with the rotational scanning geometry.

关键词： computed laminography image reconstruction reconstruction algorithm imaging field of view imaging spatial resolution

Evolution and stability of Linux kernels based on complex networks

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Science china(information Sciences) 2012年第9期55卷 1972-1982页

作者： WANG Lei,WANG Zheng,YANG Chen & ZHANG Li school of Computer Science and engineering,beihang university,beijing 100191,china school of Computer Science and engineering Beihang University Beijing China

This paper presents a novel method to study Linux kernel evolution using complex *** investigated the node degree distribution and average path length of the call graphs corresponding to the kernel modules of 223 different versions(V1.1.0 to V2.4.35),we found that the call graphs are scale-free and smallworld *** on the relationship between average path length and nodes,we propose a method to find unusual points during Linux kernel evolution using the slope of the average path *** the unusual points we identify major structural changes in kernel modules.A stability coefficient is also proposed to describe quantitatively the stability of kernel modules during ***,we verify our result through Vasa’s metrics method.

关键词： complex networks operating system scale-free networks small-world networks average path length

Logical verification of scientific discovery

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Science china(information Sciences) 2010年第4期53卷 677-684页

作者： LI Wei State Key Laboratory of Software Development Environment, school of Computer Science and engineering, beihang university, beijing 100191, china State Key Laboratory of Software Development Environment School of Computer Science and Engineering Beihang University Beijing China

This paper shows that the discovery processes of Einstein’s special theory of relativity and Darwin’s theory of evolution of species can be formally verified by R-calculus which is a logical inference system. The aim of R-calculus is to delete the principles of scientific theories which contradict empirical evidence. The paper shows that the special theory of relativity is the only and correct choice for physics to meet the experimental evidence given at the time. As far as the biology of Darwin’s time is concerned, however, the R-calculus has derived three logically correct but different theories, which are all consistent with the empirical evidence provided by Darwin and his principle of natural selection. Darwin’s theory of evolution matches one of the three theories derived by R-calculus. This theory has a logical consequence that is "each species has been independently created is erroneous". But the other two theories support the negation of the above statement. The existence of the other two theories may be a reason of the controversies over Darwin’s theory.

关键词： R-calculus theory of relativity theory of evolution

A new approach for generating function sequences——Hybrid Bridge functions derived from Walsh functions

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Progress in Natural Science:Materials International 2009年第9期19卷 1153-1158页

作者： Yan Li, Qing Chang*, Qishan Zhang school of Electronic and information engineering, beihang university, beijing 100083, china school of Electronic and information engineering Beihang University Beijing 100083 China

This paper reviews the essence of the Walsh and Bridge functions from the point of view of the recursive relationship; it also unifies their expressions. A new kind of function-the hybrid Bridge function-is constructed from the definition of the hybrid matrix, in which the row vectors are taken from the Walsh and Bridge function matrices. We also propose a new approach for generating function sequences; one that uses the column vectors of the hybrid Bridge function matrix as the new function sequences. These sequences are able to adjust the number of zeroes flexibly; thus, resolving the constraint on the application of excessive zeroes in Bridge function sequences, while at the same time maximizing the research field for function sequences. Through strict mathematical analysis, it is proved that when the initial matrix order of the parent matrices and the similarity of the hybrid matrices meet certain conditions, the hybrid function sequences exhibit good orthogonal characteristics. This provides a theoretical basis for its further applications in communication systems.

关键词： Copy theory Walsh functions Bridge functions Hybrid Bridge functions

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 College of Software Beihang University Beijing China College of Computer Beihang University Beijing China Institute of Remote Sensing and GIS Peking University Beijing 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

Application of Diagonal Recurrent Neural Network toDC Motor Speed Control Systems

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International Journal of Minerals,Metallurgy and Materials 2000年第1期14卷 68-71页

作者： Jing Wang Hui Chen information engineering school, university of Science and Technology beijing, beijing 100083, china information engineering school University of Science and Technology Beijing Beijine 100083 China

A new kind of dynamic neural network--diagonal recurrent neural network (DRNN) and its learning method and architecture are presented. A direct adaptive control scheme is also developed that is applied to a DC (Direct Current) speed control system with the ability to auto-tune PI (Proportion Integral) parameters based on combining DRNN with PI controller. The simulation results of DRNN show better control performances and potential practical use in comparison with PI controller.

关键词： diagonal recurrent neural network PI controller DC Motor speed control system

A WT-STFT combining Algorithm

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International Journal of Minerals,Metallurgy and Materials 2000年第4期14卷 315-317页

作者： Xisheng Li, Shaochun Wang (information engineering school, university of Science and Technology beijing, beijing 100083, china) information engineering school University of Science and Technology Beijing Beijing 100083 China

A fast wavelet packet (WP) algorithm is presented, in which the wavelet transform (WT) and the short-time Fourier transform (STFT) are combined. As WT produces multiresolution of frequency and time, and STFT has a fas... 详细信息

关键词： signal processing, wavelet transform short-time Fourier transform Informatid

Multimedia Data Coding and its Development

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International Journal of Minerals,Metallurgy and Materials 2000年第3期14卷 229-232页

作者： Xingye Yu, Yang Yang (information engineering school, university of Science and Technology beijing, beijing 100083, china) information engineering school University of Science and Technology Beijing Beijing 100083 China

The requirements of data coding in multimedia applications are presented, the current technique of coding and relative standards is introduced, then the work that have been doing is presented, i.e. the wavelet-based coding method and the VE (Visual Entropy)-based coding method. The experiment results prove that these methods have gained a better perceptual quality of a reconstructed image and a lower bit rate. Their performance evaluations are better than JPEG (Joint Photographic Experts Group) coding. Finally, the future topics of study are put forward.

关键词： multimedia data coding MPEG (Moving Picture Experts Group) VE (Visual Entropy)