Petronio Pulino

Controlling Dispersal Dynamics of Aedes aegypti

The dengue virus is transmitted in regions previously infested with the mosquito Aedes aegypti. To assess the spreading and establishment of the dengue disease vector, a mathematical model is developed that takes into account the diffusion and advection phenomena. A discrete model based on the cellular automata approach, which is a good framework to deal with small populations, is also developed to be compared with the continuous modeling.

New developments on the combined application of charge simulation and numerical methods for the computation of electric fields

A new mathematical treatment is proposed to the hybrid method of charge simulation and finite differences for the computation of electric fields, entirely applicable to the similar hybrid method of charge simulation and finite elements. The resulting system of linear equations is solved by making use of the fixed point theory, the QR decomposition (by using the modified Gram-Schmidt method) and the conjugate gradients squared method with a preconditioning technique. New procedures are suggested for the discretization of the boundary conditions, which lead to results with higher precision. Case studies are included. >

Numerical Simulation of the Cavitation in the Hydrodynamic Lubrication of Journal Bearings: a Parallel Algorithm

In this paper we present an algorithm for the numerical simulation of the cavitation in the hydrodynamic lubrication of journal bearings. Despite the fact that this physical process is usually modelled as a free boundary problem, we adopted the equivalent variational inequality formulation. We propose a two-level iterative algorithm, where the outer iteration is associated to the penalty method, used to transform the variational inequality into a variational equation, and the inner iteration is associated to the conjugate gradient method, used to solve the linear system generated by applying the finite element method to the variational equation. This inner part was implemented using the element by element strategy, which is easily parallelized. We analyse the behavior of two physical parameters and discuss some numerical results. Also, we analyse some results related to the performance of a parallel implementation of the algorithm.

Um método de projeção para problemas de complementaridade linear

In this article we present an iterative two-step algorithm for the numerical solution of linear complementarity problems (LCP). The algorithm presented combine the active set strategy with the square conjugated gradient method for the linear system solution. This iterative two-step algorithm was based in a similar one developed by Kocvara & Zowe (1994), that combine the symmetric successive over relaxation with projection method and the precondicioned conjugated gradient method. In the Numerical Experience section, we have tested the method for solve some LCP with non-singular matrices. Such matrices belong to semi positive definite matrix class, P-matrix class and P0-matrix class. Furthermore we show a comparision between our method and the one developed by Pardalos, Ye, Han & Kaliski (1993).

Biocybernetics : fitting the oxyhaemoglobin dissociation curve

Proposes a modified Hill model for the oxyhaemoglobin dissociation curve. The model fits normal oxyhaemoglobin dissociation experimental data quite accurately, and can easily be adapted to experimental data of subjects suffering haemoglobinopathies when available. Discusses the Adair equation, as well as correcting factors for varying temperature and pH.

Bidimensional simulation of MOSFETs in thermal equilibrium

The rapid increase in the development of new VLSI structures indicates that the most cost effective way to design semiconductor devices is using numerical simulation based on sophisticated bi or three- dimensional models. In this paper we detail the solution of the bi- dimensional Poisson equation applied to a MOSFET in thermal equilibrium. This problem, although quite simple, can give detailed information about the operation of submicron devices in certain conditions, and serves as a good introduction to the study of the dimensional effects in the operation of semiconductor structures. We obtain numerical results and establish some comparisons between devices with channels length of 5.0 micrometers and 1.0 micrometers .