Datos obtenidos el lunes 11 de febrero de 2002

Registro 1 de 4 en EI COMPENDEX (1997-1998/12) TI: Short communication comments on a recent paper dealing with the finite-analytic method AU: Ramos-JI; Garcia-Lopez-CM SO: International-Journal-of-Numerical-Methods-for-Heat-and-Fluid-Flow. v 7 n 8 1997, p 794-800. IS: 0961-5539 AB: In a study conducted recently by Montgomery and Fleeter, a finite-analytic method was used to analyze steady, two-dimensional, inviscid, compressible, subsonic flow in a nozzle. As a follow-up, the present study shows that the cell boundary conditions employed in the previous study are not exact. By means of a simple one-dimensional example, it is illustrated that the finite-analytic method is really a piecewise-parabolic approximation which involves only three consecutive grid points. A finite-analytic method is proposed which employs the exact boundary conditions at the cell boundaries and provides continuous and differentiable solutions. 6 Refs. PY: 1997 LA: English AN: EIX98144054234 Mostrar Registro Completo

Registro 2 de 4 en EI COMPENDEX (1997-1998/12) TI: Linearized Theta -methods. Part II: reaction-diffusion equations AU: Garcia-Lopez-CM; Ramos-JI SO: Computer-Methods-in-Applied-Mechanics-and-Engineering. v 137 n 3-4 Nov 15 1996, p 357-378. IS: 0045-7825 AB: Second-order accurate in space, partially-linearized, triangular and diagonal Theta -methods for reaction-diffusion equations, which employ either a standard or a delta formulation, are developed and applied to both the study of a system of one-dimensional, reaction-diffusion equations with algebraic nonlinear reaction terms and the propagation of a one-dimensional, confined, laminar flame. These methods require the solution of tridiagonal matrices for each dependent variable, and either uncouple or sequentially couple the dependent variables at each time step depending on whether they are diagonally- or triangularly-linearized techniques, respectively. Partially-linearized, diagonal methods yield larger errors than partially-linearized, triangular techniques, and the accuracy of the latter depends on the time step, standard or delta formulation, implicitness parameter and the order in which the equations are solved. Fully- and partially-linearized, operator-splitting methods for reaction-diffusion equations are also developed; the latter provide explicit expressions for the solution of the reaction operator. (Author abstract) 11 Refs. PY: 1996 LA: English AN: EIX97093481678 FTXT: ScienceDirect (tm) Mostrar Registro Completo

Registro 3 de 4 en EI COMPENDEX (1995-1996) TI: Piecewise-linearized method for ordinary differential equations: two-point boundary value problems AU: Garcia-Lopez-CM; Ramos-JI SO: International-Journal-for-Numerical-Methods-in-Fluids. v 22 n 11 Jun 15 1996, p 1089-1102. IS: 0271-2091 AB: Piecewise-linearized methods for the solution of two-point boundary value problems in ordinary differential equations are presented. These problems are approximated by piecewise linear ones which have analytical solutions and reduced to finding the slope of the solution at the left boundary so that the boundary conditions at the right end of the interval are satisfied. This results in a rather complex system of non-linear algebraic equations which may be reduced to a single non-linear equation whose unknown is the slope of the solution at the left boundary of the interval and whose solution may be obtained by means of the Newton-Raphson method. This is equivalent to solving the boundary value problem as an initial value one using the piecewise-linearized technique and a shooting method. It is shown that for problems characterized by a linear operator a technique based on the superposition principle and the piecewise-linearized method may be employed. For these problems the accuracy of piecewise-linearized methods is of second order. It is also shown that for linear problems the accuracy of the piecewise-linearized methods is superior to that of fourth-order-accurate techniques. For the linear singular perturbation problems considered in this paper the accuracy of global piecewise linearization is higher than that of finite difference and finite element methods. For non-linear problems the accuracy of piecewise-linearized methods is in most cases lower than that of fourth-order methods but comparable with that of second-order techniques owing to the linearization of the non-linear terms. (Author abstract) 7 Refs. PY: 1996 LA: English AN: EIX96333227844 Mostrar Registro Completo

Registro 4 de 4 en EI COMPENDEX (1995-1996) TI: Linearized Theta -methods. I. Ordinary differential equations AU: Ramos-JI; Garcia-Lopez-CM SO: Computer-Methods-in-Applied-Mechanics-and-Engineering. v 129 n 3 Jan 15 1996, p 255-269. IS: 0045-7825 AB: Fully-linearized Theta -methods for autonomous and non-autonomous, ordinary differential equations are derived by approximating the non-linear terms by means of the first-degree polynomials which result from Taylor's series expansions. These methods are implicit but result in explicit solutions. A-stable, consistent and convergent; however, they may be very demanding in terms of both computer time and storage because the matrix to be inverted is, in general, dense. The accuracy of fully-linearized Theta -methods is comparable to that of the standard, implicit, iterative Theta -methods, and deteriorates as the value of Theta is decreased from Theta equals 0.5, for which both Theta - and fully-linearized Theta -methods are second-order accurate. Partially-linearized Theta -methods based on the partial linearization of non-linear terms have also been developed. These methods result in diagonal or triangular matrices which may be easily solved by substitution. Their accuracy, however, is lower than that of fully-linearized Theta - methods. (Author abstract) 10 Refs. PY: 1996 LA: English AN: EIX96243142251 FTXT: ScienceDirect (tm) Mostrar Registro Completo