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Uniform Meshes (uniform + mesh)

Distribution by Scientific Domains
Engineering60%
Mathematics and Statistics40%

Selected Abstracts

Adaptive moving mesh methods for simulating one-dimensional groundwater problems with sharp moving fronts

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 11 2002
Weizhang Huang
Abstract Accurate modelling of groundwater flow and transport with sharp moving fronts often involves high computational cost, when a fixed/uniform mesh is used. In this paper, we investigate the modelling of groundwater problems using a particular adaptive mesh method called the moving mesh partial differential equation approach. With this approach, the mesh is dynamically relocated through a partial differential equation to capture the evolving sharp fronts with a relatively small number of grid points. The mesh movement and physical system modelling are realized by solving the mesh movement and physical partial differential equations alternately. The method is applied to the modelling of a range of groundwater problems, including advection dominated chemical transport and reaction, non-linear infiltration in soil, and the coupling of density dependent flow and transport. Numerical results demonstrate that sharp moving fronts can be accurately and efficiently captured by the moving mesh approach. Also addressed are important implementation strategies, e.g. the construction of the monitor function based on the interpolation error, control of mesh concentration, and two-layer mesh movement. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Input impedance calculation of dipole antenna using FDTD method

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 9 2008
Wenhua Yu
Abstract Since the input impedance of half wavelength dipole antenna is well known, therefore, a dipole antenna is frequently used to validate the computational electromagnetic method. Though its structure is relatively simple, it is not a simple problem for the most computational electromagnetic methods. In this article, we investigate the input impedance of half wavelength dipole antenna using the FDTD method. Numerical experiments have demonstrated that the FDTD method can be used to accurately calculate its input impedance using uniform mesh, nonuniform mesh, or subgridding. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2335,2337, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23631 [source]

The two-median problem on Manhattan meshes

NETWORKS: AN INTERNATIONAL JOURNAL, Issue 3 2007
Mordecai J. Golin
Abstract We investigate the two-median problem on a mesh with M columns and N rows (M , N), under the Manhattan (L1) metric. We derive exact algorithms with respect to m, n, and r, the number of columns, rows, and vertices, respectively, that contain requests. Specifically, we give an O(mn2 log m) time, O(r) space algorithm for general (nonuniform) meshes (assuming m , n). For uniform meshes, we give two algorithms both using O(MN) space. One is an O(MN2) time algorithm, while the other is an algorithm running in O(MN log N) time with high probability and in O(MN2) time in the worst case assuming the weights are independent and identically distributed random variables satisfying certain natural conditions. These improve upon the previously best-known algorithm that runs in O(mn2r) time. © 2007 Wiley Periodicals, Inc. NETWORKS, Vol. 49(3), 226,233 2007 [source]

Adaptive numerical solution of thick plates using first-order shear deformation theory.

NUMERICAL METHODS FOR PARTIAL DIFFERENTIAL EQUATIONS, Issue 1 2003
Part I: Error estimates
Abstract A posteriori error estimation employing both a residual based estimator and a recovery based estimator is discussed. Interest is focused upon the application to Reissner-Mindlin type thick plates modeled using first-order shear deformation theory, and our investigation is limited to uniform meshes of bilinear quadrilateral elements. Numerical results for selected test problems are presented for the resulting error estimators and discussed. © 2002 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 19: 44,66, 2003 [source]

MGM Optimal convergence for certain (multilevel) structured linear systems

PROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2003
Antonio Aricó Dr.
We present a multigrid algorithm to solve linear systems whose coefficient metrices belongs to circulant, Hartley or , multilevel algebras and are generated by a nonnegative multivariate polynomial f. It is known that these matrices are banded (with respect to their multilevel structure) and their eigenvalues are obtained by sampling f on uniform meshes, so they are ill-conditioned (or singular, and need some corrections) whenever f takes the zero value. We prove the proposed metod to be optimal even in presence of ill-conditioning: if the multilevel coefficient matrix has dimension ni at level i, i = 1, , , d, then only ni operations are required on each iteration, but the convergence rate keeps constant with respect to N(n) as it depends only on f. The algorithm can be extended to multilevel Toeplitz matrices too. [source]