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Finite element method for a nonsmooth elliptic equation

中国高等学校学术文摘·数学 2010年第2期5卷 191-209页

作者： Lili CHANG Wei GONG Ningning YAN State Key Laboratory of Scientific and Engineering Computing Institute of Systems Science Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing 100190 China State Key Laboratory of Scientific and Engineering Computing Institute of Computational Mathematics Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing 100190 China

In this paper, we study the finite element method for a nonsmooth elliptic equation. Error analysis is presented, including a priori and a posteriori error estimates as well as superconvergence analysis. We also propose two algorithms for solving the underlying equation. Numerical experiments are employed to confirm our error estimations and the efficiency of our algorithms.

关键词： Finite element method nonsmooth elliptic equation a priori error estimate a posteriori error estimate superconvergence analysis active set method

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Flexible alignment of images using B-spline reparameterization and L 2-gradient flows

Flexible alignment of images using B-spline reparameterizati...

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International Congress on Image and Signal Processing

作者： Xu, Guoliang Zheng, Yanmei State Key Laboratory of Scientific and Engineering Computing Institute of Computational Mathematics Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing 100190 China

ISBN: (纸本)9781424465149

In this paper, we present a new flexible alignment method to align two or more similar images. By minimizing an energy functional measuring the difference of the initial image and target image, a L2-gradient flow is derived. The flow is integrated by a finite element method in the spatial direction and a semi-implicit Euler scheme in the temporal direction. The experimental results show that the proposed method is efficient, effective and capable of capturing large variation of the initial and the target images. ©2010 IEEE.

关键词： Finite element method

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Fast facial fitting based on mixture appearance model with 3D constraint

Fast facial fitting based on mixture appearance model with 3...

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Chinese Conference on Pattern Recognition

作者： Huang, Xiangsheng Gong, Lujin Wang, Xiaoyan Institute of Automation Chinese Academy of Sciences Beijing 100190 China State Key Laboratory of Scientific and Engineering Computing Institute of Computational Mathematics and Scientific/Engineering Computing AMSS Beijing 100190 China College of Computer Science and Technology Zhejiang University of Technology Hangzhou 310023 China

ISBN: (纸本)9781424472109

Fast facial points fitting plays an important role in applications such as Human-Computer Interaction, entertainment, surveillance, and is highly relevant to the techniques of facial expression analysis, face recognition, 3D face model generation, etc. Active Appearance Models (AAMs) are generative models commonly used to fit face. They are sensitive to illumination and expression changes because they use only raw intensity to build observation models. In this paper, a real time facial points fitting approach using mixture observation models is presented. Furthermore, the 3D modes are used to constrain the AAM so that it can only generate model instances that can also be generated with the 3D modes. Finally, we give a derivative process for fast energy minimization using the inverse compositional algorithm. A coarse-to-fine fitting strategy is used for realtime and robust facial points fitting. We apply this algorithm to facial expression cloning of 3D Avatar system. Experimental results demonstrate that fitting the AAM with mixture observation models and 3D constraint outperforms other classical algorithms. ©2010 IEEE.

关键词： Mixtures

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A new reconstruction algorithm in tomography with geometric feature-preserving regularization

A new reconstruction algorithm in tomography with geometric ...

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International Conference on BioMedical engineering and Informatics (BMEI)

作者： Chong Chen Guoliang Xu Institute of Computational Mathematics and Scientific Engineering Computing State Key Laboratory of Scientific and Engineering Computing Chinese Academy of Sciences Beijing China Institute of Computational Mathematics and Scientific Engineering Computing State Key Laboratory of Scientific and Engineering Computing Chinese Academy and Sciences Beijing China

We present a new optimization-based reconstruction model with geometric feature-preserving regularization. The previous construction approach of optimization-based requires generally solving a tremendously large discrete linear system. In addition, the analytic algorithms, such as, back-projection related methods, Fourier transform based reconstruction algorithms, are sensitive to noise. These disadvantages motivate us naturally to present a new optimization-based regularization algorithm, as distinct from traditionally constructing a discrete linear system, that is based upon a continuous energy functional model like analytic one. Some theoretical derivations and numerical computing of our model are discussed. Experimental results illustrate the desirable performance of the algorithm under various noiseless data situations. And the geometric feature-preserving regularizer is used in numerical simulations to demonstrate the robustness and effectiveness of the algorithm under various contaminated data scenarios.

关键词： Image reconstruction Noise Distributed databases Mathematical model Computational modeling Numerical models Computed tomography

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Kinetics of diffusion-controlled enzymatic reactions with charged substrates

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PMC Biophysics 2010年第1期3卷 1-5页

作者： Lu, Benzhuo McCammon, J Andrew State Key Laboratory of Scientific/Engineering Computing Institute of Computational Mathematics and Scientific/Engineering Computing Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China Department of Chemistry and Biochemistry Center for Theoretical Biological Physics Department of Pharmacology Howard Hughes Medical Institute La Jolla CA 92093-0365 United States

The Debye-Hückel limiting law (DHL) has often been used to estimate rate constants of diffusion-controlled reactions under different ionic strengths. Two main approximations are adopted in DHL: one is that the solution of the linearized Poisson-Boltzmann equation for a spherical cavity is used to estimate the excess electrostatic free energy of a solution;the other is that details of electrostatic interactions of the solutes are neglected. This makes DHL applicable only at low ionic strengths and dilute solutions (very low substrate/solute concentrations). We show in this work that through numerical solution of the Poisson-Nernst-Planck equations, diffusion-reaction processes can be studied at a variety of conditions including realistically concentrated solutions, high ionic strength, and certainly with non-equilibrium charge distributions. Reaction rate coefficients for the acetylcholine-acetylcholinesterase system are predicted to strongly depend on both ionic strength and substrate concentration. In particular, they increase considerably with increase of substrate concentrations at a fixed ionic strength, which is open to experimental testing. This phenomenon is also verified on a simple model, and is expected to be general for electrostatically attracting enzyme-substrate systems. © 2010 Lu and McCammon.

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Flexible alignment of images using B-spline reparameterization and L2-gradient flows

Flexible alignment of images using B-spline reparameterizati...

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Congress on Image and Signal Processing, CISP

作者： Guoliang Xu Yanmei Zheng State Key Laboratory of Scientific and Engineering Computing Institute of Computational Mathematics Chinese Academy and Sciences Beijing China

In this paper, we present a new flexible alignment method to align two or more similar images. By minimizing an energy functional measuring the difference of the initial image and target image, a L 2 -gradient flow is derived. The flow is integrated by a finite element method in the spatial direction and a semi-implicit Euler scheme in the temporal direction. The experimental results show that the proposed method is efficient, effective and capable of capturing large variation of the initial and the target images.

关键词： Spline Image registration Linear systems Correlation Equations

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Wave propagation and boundary absorbing with the high order finite element method

Wave propagation and boundary absorbing with the high order ...

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第七届计算物理国际会议

作者： Wensheng Zhang Chaowei Wang State Key Laboratory of Scientific and Engineering Computing Institute of Computational Mathematics and Scientific/Engineering Computing Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing P.O.Box 2719 100190

Wave propagation simulation has important applications in oil ***, the finite difference method is the most popular numerical method for simulation of wave propa gation as it has high computational efficiency and is easy to handle boundary *** this paper, we focus on how to simulate wave propagation efficiently by high order Lagrange element on triangular *** the mass matrix must be inverted at each time step, the mass lumping technique is required to improve *** low order such as linear Lagrange element, the mass lumping can be implemented by using the quadratic rules for numerical integration, but it is not obvious for high order Lagrange finite element.

关键词： wave equation finite element mass lumping boundary absorbing

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LSSC-Ⅲ集群的作业调度与系统管理

LSSC-Ⅲ集群的作业调度与系统管理

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首届中国科学院超级计算应用大会(SCA2011)

作者： Qian Ying 钱莹 Cui Tao 崔涛 State Key Laboratory of Scientific and Engineering Computing Beijing 100190 China Institute of Com 科学与工程计算国家重点实验室北京 100190 中国科学院数学与系统科学研究院计算数学与科学工程计算研究所北京 100190

“科学与工程计算国家重点实验室”(LSEC)的三号集群LSSC-Ⅲ,于2010年3月建成并投入使用。在总结了实验室前两套PC机群的作业调度与系统管理经验的基础上,我们开发了一系列基于OpenPBS和Maui的适应于科学计算Linux集群用户的作业提交、... 详细信息

“科学与工程计算国家重点实验室”(LSEC)的三号集群LSSC-Ⅲ,于2010年3月建成并投入使用。在总结了实验室前两套PC机群的作业调度与系统管理经验的基础上,我们开发了一系列基于OpenPBS和Maui的适应于科学计算Linux集群用户的作业提交、调度与系统管理脚本。本文详细介绍了LSSC-Ⅲ的作业调度与系统管理方案,以期能为中小规模集群(结点数在1 024个以内)用户提供一套稳定、高效且易用的作业调度与系统管理解决方案。

关键词：计算机集群系统作业调度系统管理

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Fast Facial Fitting Based on Mixture Appearance Model with 3D Constraint

Fast Facial Fitting Based on Mixture Appearance Model with 3...

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Chinese Conference on Pattern Recognition (CCPR)

作者： Xiangsheng Huang Lujin Gong Xiaoyan Wang Institute of Automation Chinese Academy and Sciences Beijing China State Key Laboratory of Scientific and Engineering Computing AMSS Institute of Computational Mathematics and Scientific/Engineering Computing Chinese Academy and Sciences Beijing China College of Computer Science and Technology Zhejiang University of Technology Hangzhou China

关键词： Three dimensional displays Shape Active appearance model Solid modeling Face Pixel Robustness

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Electric-potential reconstructions of single particles using L2-gradient flows

Electric-potential reconstructions of single particles using...

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International Conference on BioMedical engineering and Informatics (BMEI)

作者： Ming Li Guoliang Xu Carlos O. S. Sorzano Roberto Melero Chandrajit Bajaj State Key Laboratory of Scientific and Engineering Computing Institute of Computational Mathematics Academy of Mathematics and System Sciences Chinese Academy and Sciences Beijing China Biocomputing Unit. Centro Nacional de Biotecnologia CSIC Campus University Autonoma Madrid Mexico Austin Department of Computer Sciences and Institute of Computational Engineering & Sciences University of Texas Austin Austin TX USA

In this paper, we present a stable, reliable and robust method for reconstructing a three dimensional density function from a set of two dimensional electron microscopy images. By minimizing an energy functional consisting of a fidelity term and a regularization term, a L 2 -gradient flow is derived. The flow is integrated by a finite element method in the spatial direction and an explicit Euler scheme in temporal direction. The experimental results show that the proposed method is efficient and effective.

关键词： Image reconstruction Spline Three dimensional displays Adenoviruses Microscopy Finite element methods

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