The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform

Tai Kuo Wang - One of the best experts on this subject based on the ideXlab platform.

  • Adaptive multilevel method for the air bearing problem in hard disk drives
    Tribology International, 2004
    Co-Authors: Chung Jen Lu, Shean Son Chiou, Tai Kuo Wang
    Abstract:

    An adaptive Grid-generating algorithm is constructed and integrated with the multiGrid method to form a numerical scheme that suits slider air-bearing simulation of hard disk drives. The relative truncation error, a by-product of the multiGrid method, is used in Grid adaptation criteria. Finer meshes are constructed over nodes of the current Finest Grid where the relative truncation error exceeds a predetermined tolerance. The union of these finer meshes forms a new level of Grid, which may not cover the entire domain of the coarse Grid underneath. The final Grid system thus constructed is composed of levels of uniform Grids with decreasing mesh sizes. This composite Grid structure incorporates with numerical resolution as needed and efficiency of computation. A shaped rail, negative pressure slider is used to demonstrate the effectiveness of this numerical scheme. Compared with the traditional multiGrid method, the proposed adaptive multilevel method can significantly reduce the computation work for achieving the same level of accuracy.

  • Adaptive multilevel method for the air bearing problem in hard disk drives
    Tribology International, 2004
    Co-Authors: Chung Jen Lu, Shean Son Chiou, Tai Kuo Wang
    Abstract:

    An adaptive Grid-generating algorithm is constructed and integrated with the multiGrid method to form a numerical scheme that suits slider air-bearing simulation of hard disk drives. The relative truncation error, a by-product of the multiGrid method, is used in Grid adaptation criteria. Finer meshes are constructed over nodes of the current Finest Grid where the relative truncation error exceeds a predetermined tolerance. The union of these finer meshes forms a new level of Grid, which may not cover the entire domain of the coarse Grid underneath. The final Grid system thus constructed is composed of levels of uniform Grids with decreasing mesh sizes. This composite Grid structure incorporates with numerical resolution as needed and efficiency of computation. A shaped rail, negative pressure slider is used to demonstrate the effectiveness of this numerical scheme. Compared with the traditional multiGrid method, the proposed adaptive multilevel method can significantly reduce the computation work for achieving the same level of accuracy. © 2004 Elsevier Ltd. All rights reserved.

Chung Jen Lu - One of the best experts on this subject based on the ideXlab platform.

  • Adaptive multilevel method for the air bearing problem in hard disk drives
    Tribology International, 2004
    Co-Authors: Chung Jen Lu, Shean Son Chiou, Tai Kuo Wang
    Abstract:

    An adaptive Grid-generating algorithm is constructed and integrated with the multiGrid method to form a numerical scheme that suits slider air-bearing simulation of hard disk drives. The relative truncation error, a by-product of the multiGrid method, is used in Grid adaptation criteria. Finer meshes are constructed over nodes of the current Finest Grid where the relative truncation error exceeds a predetermined tolerance. The union of these finer meshes forms a new level of Grid, which may not cover the entire domain of the coarse Grid underneath. The final Grid system thus constructed is composed of levels of uniform Grids with decreasing mesh sizes. This composite Grid structure incorporates with numerical resolution as needed and efficiency of computation. A shaped rail, negative pressure slider is used to demonstrate the effectiveness of this numerical scheme. Compared with the traditional multiGrid method, the proposed adaptive multilevel method can significantly reduce the computation work for achieving the same level of accuracy.

  • Adaptive multilevel method for the air bearing problem in hard disk drives
    Tribology International, 2004
    Co-Authors: Chung Jen Lu, Shean Son Chiou, Tai Kuo Wang
    Abstract:

    An adaptive Grid-generating algorithm is constructed and integrated with the multiGrid method to form a numerical scheme that suits slider air-bearing simulation of hard disk drives. The relative truncation error, a by-product of the multiGrid method, is used in Grid adaptation criteria. Finer meshes are constructed over nodes of the current Finest Grid where the relative truncation error exceeds a predetermined tolerance. The union of these finer meshes forms a new level of Grid, which may not cover the entire domain of the coarse Grid underneath. The final Grid system thus constructed is composed of levels of uniform Grids with decreasing mesh sizes. This composite Grid structure incorporates with numerical resolution as needed and efficiency of computation. A shaped rail, negative pressure slider is used to demonstrate the effectiveness of this numerical scheme. Compared with the traditional multiGrid method, the proposed adaptive multilevel method can significantly reduce the computation work for achieving the same level of accuracy. © 2004 Elsevier Ltd. All rights reserved.

J. Zerubia - One of the best experts on this subject based on the ideXlab platform.

  • Multiscale Markov random field models for parallel image classification
    1993 (4th) International Conference on Computer Vision, 1993
    Co-Authors: Z. Kato, M. Berthod, J. Zerubia
    Abstract:

    The authors consider multiscale Markov random field (MRF) models. It is well known that multiGrid methods can improve significantly the convergence rate and the quality of the final results of iterative relaxation techniques. A hierarchical model is proposed, which consists of a label pyramid and a whole observation field. The parameters of the coarse Grid can be derived by simple computation from the Finest Grid. In the label pyramid, a new local interaction is introduced between two neighbor Grids. This model gives a relaxation algorithm which can be run in parallel on the entire pyramid. The model allows propagation of local interactions more efficiently, giving estimates closer to the global optimum for deterministic as well as for stochastic relaxation schemes. It can also be seen as a way to incorporate cliques with far apart sites for a reasonable price.

  • ICCV - Multiscale Markov random field models for parallel image classification
    1993 (4th) International Conference on Computer Vision, 1993
    Co-Authors: Z. Kato, M. Berthod, J. Zerubia
    Abstract:

    The authors consider multiscale Markov random field (MRF) models. It is well known that multiGrid methods can improve significantly the convergence rate and the quality of the final results of iterative relaxation techniques. A hierarchical model is proposed, which consists of a label pyramid and a whole observation field. The parameters of the coarse Grid can be derived by simple computation from the Finest Grid. In the label pyramid, a new local interaction is introduced between two neighbor Grids. This model gives a relaxation algorithm which can be run in parallel on the entire pyramid. The model allows propagation of local interactions more efficiently, giving estimates closer to the global optimum for deterministic as well as for stochastic relaxation schemes. It can also be seen as a way to incorporate cliques with far apart sites for a reasonable price. >

Shean Son Chiou - One of the best experts on this subject based on the ideXlab platform.

  • Adaptive multilevel method for the air bearing problem in hard disk drives
    Tribology International, 2004
    Co-Authors: Chung Jen Lu, Shean Son Chiou, Tai Kuo Wang
    Abstract:

    An adaptive Grid-generating algorithm is constructed and integrated with the multiGrid method to form a numerical scheme that suits slider air-bearing simulation of hard disk drives. The relative truncation error, a by-product of the multiGrid method, is used in Grid adaptation criteria. Finer meshes are constructed over nodes of the current Finest Grid where the relative truncation error exceeds a predetermined tolerance. The union of these finer meshes forms a new level of Grid, which may not cover the entire domain of the coarse Grid underneath. The final Grid system thus constructed is composed of levels of uniform Grids with decreasing mesh sizes. This composite Grid structure incorporates with numerical resolution as needed and efficiency of computation. A shaped rail, negative pressure slider is used to demonstrate the effectiveness of this numerical scheme. Compared with the traditional multiGrid method, the proposed adaptive multilevel method can significantly reduce the computation work for achieving the same level of accuracy.

  • Adaptive multilevel method for the air bearing problem in hard disk drives
    Tribology International, 2004
    Co-Authors: Chung Jen Lu, Shean Son Chiou, Tai Kuo Wang
    Abstract:

    An adaptive Grid-generating algorithm is constructed and integrated with the multiGrid method to form a numerical scheme that suits slider air-bearing simulation of hard disk drives. The relative truncation error, a by-product of the multiGrid method, is used in Grid adaptation criteria. Finer meshes are constructed over nodes of the current Finest Grid where the relative truncation error exceeds a predetermined tolerance. The union of these finer meshes forms a new level of Grid, which may not cover the entire domain of the coarse Grid underneath. The final Grid system thus constructed is composed of levels of uniform Grids with decreasing mesh sizes. This composite Grid structure incorporates with numerical resolution as needed and efficiency of computation. A shaped rail, negative pressure slider is used to demonstrate the effectiveness of this numerical scheme. Compared with the traditional multiGrid method, the proposed adaptive multilevel method can significantly reduce the computation work for achieving the same level of accuracy. © 2004 Elsevier Ltd. All rights reserved.

Zhangxin Chen - One of the best experts on this subject based on the ideXlab platform.

  • Uniform convergence of Galerkin‐multiGrid methods for nonconforming finite elements for second‐order problems with less than full elliptic regularity
    Numerical Methods for Partial Differential Equations, 2002
    Co-Authors: Zhangxin Chen
    Abstract:

    In this article we prove uniform convergence estimates for the recently developed Galerkin-multiGrid methods for nonconforming finite elements for second-order problems with less than full elliptic regularity. These multiGrid methods are defined in terms of the “Galerkin approach,” where quadratic forms over coarse Grids are constructed using the quadratic form on the Finest Grid and iterated coarse-to-fine interGrid transfer operators. Previously, uniform estimates were obtained for problems with full elliptic regularity, whereas these estimates are derived with less than full elliptic regularity here. Applications to the nonconforming P1, rotated Q1, and Wilson finite elements are analyzed. The result applies to the mixed method based on finite elements that are equivalent to these nonconforming elements. © 2002 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 18: 203–217, 2002; DOI 10.1002/num.10004

  • V -cycle Galerkin-multiGrid methods for nonconforming methods for nonsymmetric and indefinite problems
    Applied Numerical Mathematics, 1998
    Co-Authors: Zhangxin Chen, Y. Kwak
    Abstract:

    Abstract In this paper we analyze a class of V -cycle multiGrid methods for discretizations of second-order nonsymmetric and/or indefinite elliptic problems using nonconforming P1 and rotated Q1 finite elements. These multiGrid methods are based on the so-called Galerkin approach where the quadratic forms over coarse Grids are constructed from the quadratic form on the Finest Grid and iterated coarse-to-fine Grid operators. The analysis shows that these V -cycle multiGrid iterations with one smoothing on each level converge at a uniform rate provided that the coarsest level in the multilevel iterations is sufficiently fine (but independent of the number of multiGrid levels). Various types of smoothers for the nonsymmetric and indefinite problems are considered and analyzed. The theory presented here also applies to mixed finite element methods for the nonsymmetric and indefinite problems.

  • The analysis of interGrid transfer operators and multiGrid methods for nonconforming finite elements.
    1997
    Co-Authors: Zhangxin Chen
    Abstract:

    In this paper we first analyze interGrid transfer operators and their iterates for some nonconforming finite elements used for discretizations of second- and fourth-order elliptic problems. Then two classes of multiGrid methods using these elements are considered. The first class is the usual one, which uses discrete equations on all levels which are defined by the same discretization, while the second one is based on the Galerkin approach where quadratic forms over coarse Grids are constructed from the quadratic form on the Finest Grid and the iterates of interGrid transfer operators, which we call the Galerkin multiGrid method. The properties of these interGrid transfer operators are utilized for the analysis of the first class, while the properties of their iterates are exploited for the second one. Convergence results available for these two classes of multiGrid methods are summarized here.