检索结果-南通市图书馆

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 [a]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

Stem cells and neurodegenerative diseases

在线全文

学校读者我要写书评

暂无评论

Science China(Life Sciences) 2008年第4期51卷 287-294页

作者： HOU LingLing & HONG Tao Institute of Biological Science and Technology, beijing jiaotong university, beijing 100044, China 1. Institute of Biological Science and Technology Beijing Jiaotong University Beijing 100044 China

Neurodegenerative diseases are characterized by the neurodegenerative changes or apoptosis of neurons involved in networks, which are important to specific physiological functions. With the de-velopment of old-aging society, the incidence of neurodegenerative diseases is on the increase. How-ever, it is difficult to diagnose for most of neurodegenerative diseases. At present, there are too few effective therapies. Advances in stem cell biology have raised the hope and possibility for the therapy of neurodegenerative diseases. Recently, stem cells have been widely attempted to treat neurodegen-erative diseases of animal model. Here we review the progress and prospects of various stem cells, including embryonic stem cells, mesenchymal stem cell and neural stem cells and so on, for the treatments of neurodegenerative diseases, such as Parkinson’s disease, Alzheimer’s disease, Hunt-ington’s disease and Amyotrophic lateral sclerosis/Lou Gehrig’s disease.

关键词： stem cells neurodegenerative diseases therapy

Micromechanical analysis of interaction energy for SMA reinforced composite

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2009年第3期52卷 610-616页

作者： ZHU YuPing1,2, DUI GuanSuo1 & DUO Liu3 1 Institute of Mechanics, beijing jiaotong university, beijing 100044, China 2 Department of Engineering Mechanics, Jiangsu university, Zhenjiang 212013, China 3 State Key Lab of Crystal Materials, Shandong university, Jinan 250100, China Institute of Mechanics Beijing Jiaotong University Beijing 100044 China Department of Engineering Mechanics Jiangsu University Jiangsu Zhenjiang 212013 China State Key Lab of Crystal Materials Shandong University Jinan 250100 China

The energy of the interaction between the matrix and the inclusions in shape memory alloy (SMA) re- inforced composite is one of the most important and complicated parts in thermodynamic constitutive theory. In this paper, the interaction energy is derived based on the classical theory of micromechanics and the thermodynamic theory. The SMA composite is treated as three phases, namely the austenitic phase, the martensite phase and the matrix phase. The interaction among the three phases is analyzed in a way close to the fact. The present expression is used to calculate the interaction energy of a typical SMA composite with attentions paid to understand of the effects of the matrix material, the fiber ge- ometry, and the fiber/matrix volume ratio. It is shown that the method developed in this paper is credible compared with the references. Some useful conclusions are obtained.

关键词： shape memory alloy interaction energy SMA composite micromechanics thermodynamics

Contact position controlling for two-dimensional motion bodies by the boundary element method

在线全文

学校读者我要写书评

暂无评论

Journal of university of Science and Technology beijing 2002年第2期9卷 138-141页

作者： Junping Pu and Yuanfeng Wang School of Civil Engineering and Architecture, Northern jiaotong university, beijing 100044, China School of Civil Engineering and Architecture Northern Jiaotong University Beijing 100044 China

An algorithm is presented for controlling two-dimensional motion contact bodies with conforming discretization. Since a kind of special boundary element is utilized in the algorithm, the displacement compatibility and traction equilibrium conditions at nodes can be satisfied simultaneously in arbitrary locations of the contact interface. In addition, a method is also proposed in which the contact boundary location can be moved flexibly on the possible contact boundary. This method is effective to deal with moving and rolling contact problems on a possible larger moving or rolling contact region. Numerical examples show effectiveness of the presented scheme.

关键词： boundary element method contact move roll

TRANSPORTATION NETWORKS:OLD AND NEW

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics(A Journal of Chinese Universities) 1996年第3期11卷 251-272页

作者： LIU YANPEI(Department of Mathematics,Northern jiaotong university, beijing 100044) Department of Mathematics Northern Jiaotong University Beijing

This paper shows a number of Problems in pure and applied mathematicsthat are solved by constructing transportation ***,it also shows thatall the solutions are characterized by forbidden configurations which are not ***,all the characterizations are much related to the graphic method which wasfound by Chinese for solving a kind of the transportation problem in the fifties.

关键词： Mathematical programming,transportation problem,network graphic method forbidden configuration.

The Existence of BIB Designs

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2000年第1期16卷 103-112页

作者： Yanxun Chang Institute of Mathematics,Northern jiaotong university,beijing 100044,P.R.China Institute of Mathematics Northern Jiaotong University Beijing 100044 P.R. China

Given any positive integers k3 and λ,let c（k,λ）denote the smallest integer such that u ∈ B（k,λ）for every integer uc（k,λ）that satisfies the congruences λv（v-1）≡0（mod k（k-1））and λ（u-1）≡0（mod k-1）.In this article we make an improvement on the bound of c（k,λ）provided by Chang in[4]and prove that c（k,λ）exp{k3k6}.In particular,c（k,1）exp{kk2}.

关键词： Wilson’s theorem Balanced incomplete block design PBD-closed

ON THE LINEAR CONVERGENCE OF PC-METHOD FOR ACLASS OF LINEAR VARIATIONAL INEQUALITIES

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 1999年第2期17卷 199-208页

作者： Nai-hua Xiu(Department of Mathematics, Nothern jiaotong university, beijing 100044, China Instituteof Applied Mathematics, Chinese Academy Of Sciences, beijing 100080, China) 北方交通大学数学系北京

This paper studies the linear convergence properties of a class of the projection and contraction methods for the affine variational inequalities, and proposes a necessary and sufficient condition under which PC-Metho... 详细信息

关键词： affine variational inequality projection and contraction method linear convergence

The spectrum for large sets of pure directed triple systems

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2006年第8期49卷 1103-1127页

作者： ZHOU Junling, CHANG Yanxun & Jl Lijun Institute of Mathematics, beijing jiaotong university, beijing 100044, China Department of Mathematics, Suzhou university, Suzhou 215006, China 1. Institute of Mathematics Beijing Jiaotong University Beijing 100044 China 2. Department of Mathematics Suzhou University Suzhou 215006 China

An LPDTS(υ) is a collection of 3(υ - 2) disjoint pure directed triple systems on the same set of υ elements. It is showed in Tian's doctoral thesis that there exists an LPDTS(υ) for υ≡ 0,4 (mod 6), υ≥ 4. In this paper, we establish the existence of an LPDTS(υ) for υ≡ 1, 3 (mod 6), υ＞ 3. Thus the spectrum for LPDTS(υ) is completely determined to be the set {υ:υ≡0, 1 (mod 3),υ≥4}.

关键词： large set, oriented triple system, pure, directed candelabra system.

An efficient algorithm for solving supply chain network equilibria and equivalent supernetwork based traffic network equilibria

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2010年第12期53卷 3264-3274页

作者： XU Meng1 & GAO ZiYou2 1 MOE Key Laboratory for Urban Transportation Complex Systems Theory and Technology, beijing jiaotong university, beijing 100044, China 2 Institute of Systems Science, School of Traffic and Transportation, beijing jiaotong university, beijing 100044, China 1. MOE Key Laboratory for Urban Transportation Complex Systems Theory and Technology Beijing Jiaotong University Beijing 100044 China2. Institute of Systems Science School of Traffic and Transportation Beijing Jiaotong University Beijing 100044 China

This paper is concerned with the algorithm of the supply chain network equilibrium model and its equivalent supernetwork based traffic network equilibrium model with elastic demands. Both models are further written as nonlinear complementarity problems. Semismooth least squares reformulations of the complementarity problems are presented and their convergence properties are investigated. Considering the drawbacks of Quasi-Newton method (using the Fischer-Burmeister function), a semi-smooth Levenberg-Marquardt-type method is proposed to solve the problems. Numerical examples show that the Levenberg-Marquardt-type method can solve the supply chain network equilibrium model and its equivalent supernetwork based traffic network equilibrium model significantly, and is more efficient than the Quasi Newton method and the modified projection method. Furthermore, the Levenberg-Marquardt-type method with the equivalent supernetwork based complementarity formulation can be implemented faster than with the supply chain network equilibrium complementarity formulation.

关键词： supply chain networks traffic network equilibrium supernetwork nonlinear complementarity problem Levenberg Marquardt-type method

The Spectrum of (gv, g, 3, λ)-dDF in Zgv

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2010年第2期26卷 377-392页

作者： Xiao Miao WANG Yan Xun CHANG Institute of Mathematics, beijing jiaotong university, beijing 100044, P. R. China Institute of Mathematics Beijing Jiaotong University Beijing P. R. China

In this paper, several recursive constructions for directed difference family and perfectdirected difference family are presented by means of difference matrix and incomplete difference *** the necessary and sufficient conditions for the existence of a (gv, g, 3, λ)-directed differencefamily in Zare established. As a consequence, the necessary and sufficient conditions for the existenceof a cyclic directed group divisible design with block size three and type g~v are obtained.

关键词： directed difference family incomplete difference matrix perfect directed difference family