The purpose of this paper is twofold. The first is to remove a possible ill-posedness related to a local minimax method developed in SIAM J. Sci. Comput. 23 (2001) 840-865, SIAM J. Sci. Comput. 24 (2002) 840-865 and t...
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The purpose of this paper is twofold. The first is to remove a possible ill-posedness related to a local minimax method developed in SIAM J. Sci. Comput. 23 (2001) 840-865, SIAM J. Sci. Comput. 24 (2002) 840-865 and the second is to provide a local characterization for nonminimax type saddle points. To do so, a local L-perpendicular to selection is defined and a necessary and sufficient condition for a saddle point is established, which leads to a min-orthogonal method. Those results exceed the scope of a minimax principle, the most popular approach in critical point theory. An example is given to illustrate the new theory. With this local characterization, the local minimax method in SIAM J. Sci. Comput. 23 (2001) 840-865, SIAM J. Sci. Comput. 24 (2002) 840-865 is generalized to a local min-orthogonal method for finding multiple saddle points. In a subsequent paper, this approach is applied to define a modified pseudo gradient (flow) of a functional for finding multiple saddle points in Banach spaces. (C) 2003 Elsevier Inc. All rights reserved.
The equivalence between the propagation of dispersive modal fields in two-dimensional waveguides, and plane waves in a one-dimensional plasma is presented. Exploitation of this equivalence allows a time domain variant...
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The equivalence between the propagation of dispersive modal fields in two-dimensional waveguides, and plane waves in a one-dimensional plasma is presented. Exploitation of this equivalence allows a time domain variant of the effective index approach to be used to model dispersive waveguides problems very efficiently. A time domain integral equation is developed for this important practical case and the stability of a computer algorithm based upon it is improved by means of both a semi-implicit formulation and the use of a modified space - time mesh.
A new class of body-fitted grid system that can keep the third-order accuracy in time and space is proposed with the help of the CIP (constrained interpolation profile/cubic interpolated propagation) method. The grid ...
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A new class of body-fitted grid system that can keep the third-order accuracy in time and space is proposed with the help of the CIP (constrained interpolation profile/cubic interpolated propagation) method. The grid system consists of the straight lines and grid points moving along these lines like abacus - Soroban in Japanese. The length of each line and the number of grid points in each line can be different. The CIP scheme is suitable to this mesh system and the calculation of large CFL (>10) at locally refined mesh is easily performed. Mesh generation and searching of upstream departure point are very simple and almost mesh-free treatment is possible. Adaptive grid movement and local mesh refinement are demonstrated. (C) 2003 Elsevier B.V. All rights reserved.
A novel, simple iterative algorithm is used to calculate the temperature distribution in a finite medium for the case of non-Fourier (hyperbolic) heat conduction. In this algorithm the temperature is calculated explic...
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A novel, simple iterative algorithm is used to calculate the temperature distribution in a finite medium for the case of non-Fourier (hyperbolic) heat conduction. In this algorithm the temperature is calculated explicitly in one simple calculation that is repeated for each time step as the heat wave propagates through the medium with constant speed. When the wave reaches a boundary of the medium, it bounces back and moves in the opposite direction. All simple initial and boundary conditions can be modelled. An example of using the algorithm for the case of a finite, thermally insulated medium is given, and the results are compared with an exact analytical solution.
作者：
Mullan, HBUniv Coll Swansea
EPSRC Engn Doctorate Ctr Automot Appl Corus RD&T Swansea SA2 8PP W Glam Wales
This paper investigates the major difficulty associated with the bending of sheet steel products, namely that of material elastic recovery (springback). Key material, and loading factors that influence springback have...
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This paper investigates the major difficulty associated with the bending of sheet steel products, namely that of material elastic recovery (springback). Key material, and loading factors that influence springback have been assessed from an experimental study of this phenomenon, using a variety of forming methods. The results of which, in conjunction with previously published data are used to derive an expression for predicting springback using a numerical algorithm method. In addition, comparison is made between the best performing analytical model and that of the numerical algorithm derived in this study. (C) 2004 Published by Elsevier B.V.
Dumped heat wave algorithm is used to approximately calculate temperature distribution in a finite, one-dimensional medium and the results are compared to known analytical solutions and finite difference numerical alg...
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Dumped heat wave algorithm is used to approximately calculate temperature distribution in a finite, one-dimensional medium and the results are compared to known analytical solutions and finite difference numerical algorithm. The proposed algorithm can serve as a rapid, easy to understand and easy to implement alternative to existing numerical and analytical procedures for calculating the temperature distribution in solids. (C) 2003 Elsevier Inc. All rights reserved.
The Gauss-Chebyshev quadrature formula is suggested to calculate the transparency of the potential barrier at the metal-vacuum boundary. It is shown that in the most interesting cases ONE node is enough to obtain accu...
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The Gauss-Chebyshev quadrature formula is suggested to calculate the transparency of the potential barrier at the metal-vacuum boundary. It is shown that in the most interesting cases ONE node is enough to obtain accuracy of a few percent when calculating thermo-field. electron emission current density.
Details are given of the development of a two-dimensional vertical numerical model for simulating unsteady free-surface flows, using a non-hydrostatic pressure distribution. In this model, the Reynolds equations and t...
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Details are given of the development of a two-dimensional vertical numerical model for simulating unsteady free-surface flows, using a non-hydrostatic pressure distribution. In this model, the Reynolds equations and the kinematic free-surface boundary condition are solved simultaneously, so that the water surface elevation can be integrated into the solution and solved for, together with the velocity and pressure fields. An efficient numerical algorithm has been developed, deploying implicit parameters similar to those used in the Crank-Nicholson method, and generating a block tri-diagonal algebraic system of equations. The model has been applied to simulate a range of unsteady flow problems involving relatively strong vertical accelerations. The results show that the numerical algorithm described is able to produce accurate predictions and is also easy to apply. Copyright (C) 2001 John Wiley & Sons, Ltd.
We present an algorithm to analytically solve two-person affine-quadratic difference games, and to numerically calculate nonlinear quadratic difference games using an appropriate local linearization procedure for a ti...
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We present an algorithm to analytically solve two-person affine-quadratic difference games, and to numerically calculate nonlinear quadratic difference games using an appropriate local linearization procedure for a time-structure relevant for economic modeling. The numerical approximation and the derivation of different solutions of the underlying affine-quadratic dynamic games are explained; in particular, we determine open-loop and feedback Nash and Stackelberg equilibrium solutions and Pareto-optimal solutions.
The paper deals with the numerical analysis of large elastic-plastic deformation behavior of anisotropically damaged ductile solids based on a generalized macroscopic theory within the framework of nonlinear continuum...
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The paper deals with the numerical analysis of large elastic-plastic deformation behavior of anisotropically damaged ductile solids based on a generalized macroscopic theory within the framework of nonlinear continuum damage mechanics. Estimates of the stress and strain histories are obtained from a straightforward numerical integration algorithm based on operator split methodology which employs an inelastic (damage plastic) predictor followed by an elastic corrector step. The finite element method is used to approximate the linearized variational problem. Furthermore, identification of material parameters is discussed. numerical simulation of the elastic-plastic deformation behavior of damaged tension specimens demonstrate the efficiency of the formulation. (C) 2003 Elsevier B.V. All rights reserved.
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