Diffusion Reaction Equations
Mostrando 13-24 de 39 artigos, teses e dissertações.
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13. Nonlinear subgrid methods for convection-difusion-reaction problem / Métodos submalhas não lineares para o problema de convecção-difusão-reação
This work presents a general framework for approximating convection-diffusion-reaction equations based on principles of scale separation. A two-level decomposition of the discrete approximation spaces is performed and the local problem is modified introducing an artificial viscosity acting only on the subgrid scales. The key feature is the local control comi
Publicado em: 2007
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14. Avascular tumor modelling: from celular automata to multiscale models / Modelagem de tumores avasculares: de autômatos celulares a modelos de multiescala
The majority of the clinically used anti-cancer therapies has been developed empirically [1], but the tumour and organism response to these therapies are nonlinear. Therefore mathematical models might be complementary (may be necessary) tools for the understanding of the drug response dynamics in the organism. In this dissertation, some of these models are s
Publicado em: 2007
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15. Um sistema presa-predador com evasão mediada por feromônio de alarme / A predator-prey model with pursuit and evasion triggered by alarm pheromones
Pattern, structure and emergent collective properties are ubiquitous in systems with many units (alive or inanimated) coupled through nonlinear interactions. Within this context, the study of cooperative phenomena in population dynamics of ecological interest has attracted the attention of the mathematicians and physicists since Lotka and Volterra in the 192
Publicado em: 2006
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16. Gradient vector flow and out-of-core image segmentaion by deformable models / Fluxo do Vetor Gradiente e Modelos Deformáveis Out-of-Core para Segmentação e Imagens
Main memory limitations can lower the performance of segmentation applications for large images or even make it undoable. In this work we integrate the T-Surfaces model and Out-of-Core isosurface generation methods in a general framework for segmentation of large image volumes. T-Surfaces is a parametric deformable model based on a triangulation of the image
Publicado em: 2006
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17. Simulações de ondas reentrantes e fibrilação em tecido cardíaco, utilizando um novo modelo matemático / Simulations of re-entrant waves and fibrillation in cardiac tissue using a new mathematical model
Atrial and ventricular fibrillation are characterized by a disorganized electrical activity of the cardiac muscle. While normal heart contracts uniformly as a whole, during fibrillation several small regions of the muscle contracts locally and uncoordinatedly. The present work introduces a new mathematical model for the qualitative study of fibrillation. The
Publicado em: 2005
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18. Modelagem e analise de digestores Kraft descontinuo
Global1y, the Kraft pulping process is beginning to get use of the benefits of the recent developments in the modeling area and process control. Advanced techniques of simulation and control offer tools that allow the analysis and efficient design of multivariable non-linear process, involving the optimization and the advanced control of the process. The pul
Publicado em: 2004
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19. DifusÃo e transporte na presenÃa de macromolÃculas. Imagens e espectroscopia por RMN
The electronic Overhauser effect was employed to enhance nuclear magnetic resonance images obtained in a magnetic eld of only 16 mT. Despite the weak magnetic eld, the technique can reveal, in some systems, various aspects of ionic transport and kinetics apparently not observed in conventional high-eld magnetic resonance imaging. We employed Overhauser imagi
Publicado em: 2004
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20. Mass transfer in porous media with heterogeneous chemical reaction
In this paper, the modeling of the mass transfer process in packed-bed reactors is presented and takes into account dispersion in the main fluid phase, internal diffusion of the reactant in the pores of the catalyst, and surface reaction inside the catalyst. The method of volume averaging is applied to obtain the governing equation for use on a small scale.
Brazilian Journal of Chemical Engineering. Publicado em: 2003-06
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21. Contribuição a simulação computacional do processo de LPCVD
This work deals with the study and simulation of LPCVD-Low Pressure Chemical Vapour Deposition- a basic process for thin film deposition. The reaction of silicon deposition by silane pyrolisis is adopted for its simplicity and importance without sacrifieing the quality of treatment. To begin with, we present the atmospheric presure CVD technique in the light
Publicado em: 1990
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22. Quantum statistical mechanical theory of diffusion and reaction on solid surfaces
We present the derivation of the general kinetic equations of diffusion and diffusion with interaction (or chemical reaction) on solid surfaces (or in dense media) by using the density matrix method. We indicate several problems to which this formalism applies and, in particular, discuss the damping effect on diffusion.
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23. Analysis of Reaction-Diffusion Systems with Anomalous Subdiffusion
Reaction-diffusion equations are the cornerstone of modeling biochemical systems with spatial gradients, which are relevant to biological processes such as signal transduction. Implicit in the formulation of these equations is the assumption of Fick's law, which states that the local diffusive flux of species i is proportional to its concentration gradient;
The Biophysical Society.
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24. Kinetics of Heterogeneous Chemical Reactions: A Theoretical Model for the Accumulation of Pesticides in Soil
A theoretical model for the accumulation of pesticides in soil has been proposed and discussed from the viewpoint of heterogeneous reaction kinetics with a basic aim to understand the complex nature of soil processes relating to the environmental pollution. In the bulk of soil, the pesticide disappears by diffusion and a chemical reaction; the rate processes