| 6/2000 |
Parallel solution of contact problems Zdenek Dostál, Francisco A. M. Gomes Neto, Sandra A. Santos An efficient non-overlapping domain decomposition algorithm of the Neumann-Neumann type for solving both coercive and semicoercive frictionless contact problems of elasticity has been recently presented. The method reduces, by the duality theory of convex programming, the discretized problem to a quadratic programming problem with simple bounds and equality constraints on the contact interface. This dual problem is further modified by means of orthogonal projectors to the natural coarse space, and the resulting problem is solved by an augmented Lagrangian type algorithm. The projectors guarantee an optimal rate of convergence for the solution of auxiliary linear problems by the conjugate gradients method. With this approach, it is possible to deal separately with each body or subdomain, so that the algorithm can be implemented in parallel. In this paper, an efficient parallel implementation of this method is presented, together with numerical experiments that indicate the high parallel scalability of the algorithm.  rp-2000-6.pdf |
| 5/2000 |
A study of the initialization problem for the magnetohydrodynamic type equations Eduardo A. Notte-Cuello, Marko A. Rojas-Medar, M. Santos The initialization problem for the magnetohydrodynamic type equations in a 2d bounded domain is formulated as an optimal control problem. We prove that this problem has at least one solution and at most finite many solutions. rp-2000-5.pdf |
| 4/2000 |
Periodic solutions of a generalized Boussinesq model for thermally driven convection in exterior domains Antônio Carlos Moretti, Marko A. Rojas-Medar, M. D. Rojas-Medar We establish the existence of periodic weak solutions of a generalized Boussinesq model for thermally driven convection in exterior domains. rp-2000-4.pdf |
| 3/2000 |
Uma introdução às funções invexas diferenciáveis com aplicações em otimização Adilson J. Vieira-Brandão, Marko A. Rojas-Medar, G. N. Silva The notion of invex functions was introduced by Hanson in 1981as a generalization of convex functions. In fact, let $f: \Re^n\rightarrow \Re$ be a differentiable function. The function $f$is called invex if there exists a map $\eta : \Re^n \times \Re^n\rightarrow \Re^n$ such that, for all $x,u \in \Re^n$,\[f(x) - f(u) \geq f'(u) \cdot \eta(x,u).\]The convex case corresponds to $\eta(x,u)=x - u$. It isremarkable that many results in optimization involving convexfunctions actually hold for invex functions. In this article wecompile some of these results. rp-2000-3.pdf |
| 2/2000 |
Approximating characteristics of multiplier operators on S 2 Benjamin Bordin, Alexander Kushpel, Sérgio A. Tozoni Walsh functions on $S^{2}$ are introduced and considered. We are demonstrating different properties of such functions and establishing sharp orders of $\epsilon$ - entropy for a wide range of multiplier operators on $S^{2}$. The analysis is essentially based on martingale technique and estimates of volumes of special convex bodies which are of independent interest. rp-2000-2.pdf |
| 1/2000 |
Uma implementação de pontos interiores para fluxo em redes lineares por partes Clóvis Perin, M. Mello, Fábio A. S. Marins rp-2000-1.pdf |
| 71/1999 |
The Hopf invariant conjectures and the homology of manifolds Ricardo N. Cruz  rp-1999-71.gif, rp-1999-71.pdf |
| 70/1999 |
On the regularization of mixed complementarity problems Roberto Andreani, José Mario Martínez, Benar F. Svaiter rp-1999-70.gif, rp-1999-70.pdf |
| 69/1999 |
Reformulation of variational inequalities on a simplex and compactification of complementarity problems Roberto Andreani, José Mario Martinez rp-1999-69.gif, rp-1999-69.pdf |
| 68/1999 |
Covariant Derivatives on Minkowski Manifolds Virginia V. Fernández, Antonio M. Moya, Waldyr A. Rodrigues Jr. rp-1999-68.gif, rp-1999-68.pdf |
