检索结果-南通市图书馆

A class of discounted models for singular diffusion control

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2000年第5期45卷 405-408页

作者： LIU Kunhui, QIN Mingda & LU Chuanlai1. College of Sciences, Northern jiaotong university, beijing 100044, china 2. department of mathematics and Mechanics, beijing university of Science and Technology, beijing 100083 .china 3. department of Information Engineering, beijing university of Posts and Telecommunications, beijing 100876, china Correspondence should be addressed to Lu Chuanlai College of Sciences Northern Jiaotong University Beijing China department of mathematics and Mechanics Beijing University of Science and Technology Beijing China department of Information Engineering Beijing University of Posts and Telecommunications Beijing China

A kind of discounted problems for singular diffusion control have been studied. The drift and diffusion coefficients of state process are nonlinear. The class of models has been basically extended from a corresponding one established by Karatzes et al. before. By applying some analysis methods different from earlier works, the sufficient and necessary conditions of the existence of optimal control have been obtained. If an optimal control exists, it is a 'transient reflection' of state process for two lines.

关键词： stochastic control variational equation singular stochastic control.

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

在线全文

学校读者我要写书评

暂无评论

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

An improved reduced-rank STAP interference suppression method in design of GNSS receivers

在线全文

学校读者我要写书评

暂无评论

Science china(Information Sciences) 2012年第10期55卷 2329-2342页

作者： GONG WenFei & SUN Xin School of Electronics and Information Engineering,beijing jiaotong university,beijing 100044,china School of Electronics and Information Engineering Beijing Jiaotong University Beijing China

In this paper,we address the problem of interference cancellation in global positioning system(GPS) receiver using an adaptive reduced-rank space-time adaptive processing(STAP) interference suppression method based on multistage nested Wiener filter(MSNWF).This improved adaptive reduced-rank method is based on the improved Gerschgorin radii ***,the cross-correlations between the desired signals of the adjacent stages of MSNWF are directly used to calculate the Gerschgorin radii instead of employing the eigenvalue decomposition of the covariance ***,a heuristic decision rule based on Gerschgorin disk estimator(GDE) is employed to estimate the rank of interference *** optimal rank can be adaptively selected without increasing the *** and results of the experiment show that the proposed method further reduces the computation of STAP and enhances its real-time property with the interference suppression performance unaffected.

关键词： global positioning system reduced-rank space-time adaptive processing multistage nested Wiener filter Gerschgorin disk estimator

Stem cells and neurodegenerative diseases

在线全文

同方期刊数据库

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 Institute of Biological Science and Technology Beijing Jiaotong University Beijing 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

Multi-parameter infinite-dimensional(r,δ)-OU process

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1999年第5期44卷 418-423页

作者： WANG ZikunInstitute of mathematics, Shantou university, Shantou 515063, china department of mathematics, beijing Normal university, beijing 100875, china Institute of mathematics Shantou University Shantou China department of mathematics Beijing Normal University Beijing China

The definition of n-parameter infinite-dimensional (r, δ) -Ornstein-Uhlenbeck process {X_t (·)}((r,δ)-OUP_n~∞ for short) is given. The absolute continuity of distribution μ_t of X_t(·) and the limit of X_t(·) w... 详细信息

关键词： multi-parameter (r δ)-OUPn∞ absolute continuity in hierarchy.

L~∞ CONVERGENCE OF QUASI-CONFORMING FINITE ELEMENTS FOR THE BIHARMONIC EQUATION

在线全文

学校读者我要写书评

暂无评论

Journal of Computational mathematics 1995年第2期13卷 108-122页

作者： Wang Ming (department of mathematics, Peking university, beijing, china) 北京大学数学系北京

In this paper we consider the L∞ convergence for quasi-conforming finite ele-ments solving the boundary value probzlems of the biharmonic equation and give the nearly optimal order L∞ estimates.

关键词：双调和方程拟共形有限元 L↑∞收敛性 L↑∞估计

Existence of the solutions and the attractors for the large-scale atmospheric equations

在线全文

学校读者我要写书评

暂无评论

Science china Earth Sciences 2006年第6期49卷 650-660页

作者： HUANG Haiyang1 & GUO Boling2 1. department of mathematics, beijing Normal university, beijing 100875, china 2. Institute of Applied Physics and Computational mathematics, beijing 100080, china department of mathematics Beijing Normal University Beijing China Institute of Applied Physics and Computational mathematics Beijing China

In this paper, firstly, the proper function space is chosen, and the proper expression of the operators is introduced such that the complex large-scale atmospheric motion equations can be described by a simple and abstract equation, by which the definition of the weak solution of the atmospheric equations is made. Secondly, the existence of the weak solution for the atmospheric equations and the steady state equations is proved by using the Galerkin method. The existence of the non-empty global attractors for the atmospheric equations in the sense of the Chepyzhov-Vishik’s definition is obtained by constructing a trajectory attractor set of the atmospheric motion equations. The result obtained here is the foundation for studying the topological structure and the dynamical behavior of the atmosphere attractors. Moreover, the methods used here are also valid for studying the other atmospheric motion models.

关键词： atmosphere equations, weak solution, trajectory attractor, global attractor, equilibrium.

DIMENSIONS OF SELF-AFFINE SETS WITH OVERLAPS

在线全文

学校读者我要写书评

暂无评论

Chinese Annals of mathematics,Series B 2003年第3期24卷 275-284页

作者： HUA Su department of mathematics, Tsinghua university, beijing 100084, china. department of mathematics Tsinghua University Beijing 100084 China

The authora develop an algorithm to show that a class of self-affine sets with overlaps can be viewed as sofic affine-invariant sets without overlaps,thus by using the results of [11] and [10],the hausdorff and minkow... 详细信息

关键词： self-affine set overlap hausdorff dimension minkowski dimension

Oblique Derivative Problems for Second OrderNonlinear Equations of Mixed Type inMultiply Connected Domains

在线全文

学校读者我要写书评

暂无评论

Communications in Nonlinear Science and Numerical Simulation 1999年第4期4卷 281-284页

作者： Guochun WEN(department of mathematics, Peking university, beijing 100871, china) department of mathematics Peking University Beijing 100871 China

1FormulationoftheProblemLetDbeNconnectedboundeddomaininthecomplexplaneCwiththeboundaryNZNOD=WUL,wherer=ZrjEn（00},L=ULi’andrhastheendj=1j=1poiatsal=02,LiaredeadedasLI={x=;)05x51}L:={x=--y+hi,hi... 详细信息

关键词： oblique derivative problems quasinonlinear equations of mixed type mul-tiply connected domains.