| 8/2003 |
Multilevel Pseudo-Wavelet Schemes: a Consistency Analysis J. E. Castilho, Sônia M. Gomes The study of this paper is devoted to the analysis of multilevel approximation schemes, in the context of multiresolution analysis. We have particular interest in expansions where the coefficients are obtained in terms of discrete convolutions of function point values with some specific wheights. In the first part we analyze aspects, such as, algorithm of construction, their accuracy and multilevel implementation for three cases: interpolation, quasi-interpolation and discrete projection. The second part is dedicated to hybrid formulations for the discretization of nonlinear differential operators. The idea is to combine two different approximation schemes: one approximation scheme is used for functions or linear terms; another one, defined in terms of function point values, is used for nonlinear operations. Taking the bilinear advection operator as a model, we establish the consistency of the discretizations in terms of the order of the truncation error.  rp-2003-8.pdf |
| 7/2003 |
Stochastic Exponential in Lie Groups and its Applications Pedro J. Catuogno, Paulo R. C. Ruffino The aim of this article is to develop new simple proofs for the basic formulas of stochastic analysis in Lie groups, in particular the stochastic exponential and logarithm. We present applications to direct proofs of the (multiplicative) DoobMeyer decomposition, Girsanov theorem for semimartingales in Lie groups and solution of stochastic Lax equations. rp-2003-7.pdf |
| 6/2003 |
Notas Sobre os Espaços de Besov e a Equação de Vlasov-Poisson Marcelo M. Santos rp-2003-6.pdf |
| 5/2003 |
Um Método Iterativo para Minimização de Quadráticas em Caixas Lucas Garcia Pedroso, Maria A. Diniz-Ehrhardt In this work we focus our attention on a variation of the conjugate gradient method for bound--constrained quadratic minimization. This approach is implemented in the subroutine QUACAN, a software developed by A. Friedlander, J.M. Martinez and S.A. Santos, from DMA -- IMECC (UNICAMP). Our aim is to insert preconditioners to the method, trying to accelerate its convergence. Numerical experiments are presented. rp-2003-5.pdf |
| 4/2003 |
Simulação Numérica da Dispersão-Advecção de Pesticidas sob o Efeito da Temperatura do Solo: o Modelo DAPESTE Lourival Costa Paraíba, Petrônio Pulino A dispersion-advection equation, which is denominated DAPESTE model, of one-dimensional evolution to simulate pesticide leaching in soil with sinusoidal function to describe the daily average soil temperature at different depths will be presented. In numerical simulation, the Finite Elements Method (FEM) will be used for the space semi-discretization and the Backward Euler Method for time discretization. It will be used appropriated FEM for dispersion-advection problems in which the predominat advective transport over the dispersive one. Let us suppose that the pesticide diffusivities in the gaseous and aqueous soil phases depend on the soil temperature. In this way, the effective hydrodynamic dispersion coefficient of the dispersion-advection equation will depend on the soil temperature. The pesticide air-water partition coefficient of the Henry law, varying with the temperature, will be determined by the Clausius-Clapeyron equation. The van't Hoff equation will be used to determine the temperature dependence of the pesticide soil sorption coefficient. The Arrhenius equation will be used to estimated the effect of the soil temperature on the pesticide degradation rate. These temperature dependence relationships can help comprehend the pesticide behavior in the soil under different scenarios of the soil temperatures, especially in pesticide concentration leaching and its half-life in soil. rp-2003-4.pdf |
| 3/2003 |
The Use of Unitary Functions in the Behaviour Analysis of Elliptic Integrals Valério Ramos Batista We show how unitary functions can simplify the analysis of some elliptic integrals. rp-2003-3.pdf |
| 2/2003 |
Hydrostatic Stokes equations with non-smooth Neumann data Francisco Guillén-González, Marko A. Rodríguez-Bellido, Marko A. Rojas-Medar rp-2003-2.pdf |
| 1/2003 |
Stationary solution of the Navier-Stokes equations for inhomogeneous incompressible fluids in 2d domains with channels having bounded cross sections Ammar Khodja Farid, Marcelo M. Santos We consider the boundary value problem for the stationary Navier-Stokes equations describing an inhomogeneous incompressible fluid in infinite and semi-infinite channels with bounded cross sections. We show the existence of a weak solution with density in $L^{\infty}$ and arbitrary fluxes for the velocity and momentum. We also solve the density-dependent Leray's problem when the flux for the velocity is small. (The authors are supported by CNPq/Brazil: 451387/00-7, 453155/00-6, Pronex/27697100500 300050/92-5,and FAPESP/Brazil: 2000/07015-3.) rp-2003-1.pdf |
| 76/2002 |
Characterization of Solutions in Variational Problems. Duality M. Arana-Jiménez, R. Osuna-Gómez, G. Ruiz-Garzón, Marko A. Rojas-Medar In this paper we introduce a new class of pseudoinvex functions for variational problems. Using this new concept, we obtain a suffcient and necessary condition for a critical point of the variational problem to be an optimal solution. Weak, strong and converse duality are established. rp-2002-76.pdf |
| 75/2002 |
Population Dynamics by Fuzzy Differential Inclusions Yurilev Chalco-Cano, Rodney C. Bassanezi, Marko A. Rojas-Medar, Marina T. Mizukoshi We introduced another point of view of population dynamics using the theory of fuzzy differential inclusions. We give an application example as well as a study of stability for this example. rp-2002-75.pdf |
