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A hybrid method for nonlinear least squares that uses quasi-Newton updates applied to an approximation of the Jacobian matrix

Lukšan, Ladislav, Vlček, Jan (2019)

Programs and Algorithms of Numerical Mathematics

In this contribution, we propose a new hybrid method for minimization of nonlinear least squares. This method is based on quasi-Newton updates, applied to an approximation A of the Jacobian matrix J , such that A T f = J T f . This property allows us to solve a linear least squares problem, minimizing A d + f instead of solving the normal equation A T A d + J T f = 0 , where d R n is the required direction vector. Computational experiments confirm the efficiency of the new method.

A Hybrid Model Describing Different Morphologies of Tumor Invasion Fronts

M. Scianna, L. Preziosi (2012)

Mathematical Modelling of Natural Phenomena

The invasive capability is fundamental in determining the malignancy of a solid tumor. Revealing biomedical strategies that are able to partially decrease cancer invasiveness is therefore an important approach in the treatment of the disease and has given rise to multiple in vitro and in silico models. We here develop a hybrid computational framework, whose aim is to characterize the effects of the different cellular and subcellular mechanisms involved...

A hybrid scheme to compute contact discontinuities in one-dimensional Euler systems

Thierry Gallouët, Jean-Marc Hérard, Nicolas Seguin (2002)

ESAIM: Mathematical Modelling and Numerical Analysis - Modélisation Mathématique et Analyse Numérique

The present paper is devoted to the computation of single phase or two phase flows using the single-fluid approach. Governing equations rely on Euler equations which may be supplemented by conservation laws for mass species. Emphasis is given on numerical modelling with help of Godunov scheme or an approximate form of Godunov scheme called VFRoe-ncv based on velocity and pressure variables. Three distinct classes of closure laws to express the internal energy in terms of pressure, density and additional...

A hybrid scheme to compute contact discontinuities in one-dimensional Euler systems

Thierry Gallouët, Jean-Marc Hérard, Nicolas Seguin (2010)

ESAIM: Mathematical Modelling and Numerical Analysis

The present paper is devoted to the computation of single phase or two phase flows using the single-fluid approach. Governing equations rely on Euler equations which may be supplemented by conservation laws for mass species. Emphasis is given on numerical modelling with help of Godunov scheme or an approximate form of Godunov scheme called VFRoe-ncv based on velocity and pressure variables. Three distinct classes of closure laws to express the internal energy in terms of pressure, density...

A hyperbolic model for convection-diffusion transport problems in CFD: numerical analysis and applications.

Héctor Gómez, Ignasi Colominas, Fermín L. Navarrina, Manuel Casteleiro (2008)

RACSAM

In this paper we present a numerical study of the hyperbolic model for convection-diffusion transport problems that has been recently proposed by the authors. This model avoids the infinite speed paradox, inherent to the standard parabolic model and introduces a new parameter called relaxation time. This parameter plays the role of an “inertia” for the movement of the pollutant. The analysis presented herein is twofold: first, we perform an accurate study of the 1D steady-state equations and its...

A hyperbolic model of chemotaxis on a network: a numerical study

G. Bretti, R. Natalini, M. Ribot (2014)

ESAIM: Mathematical Modelling and Numerical Analysis - Modélisation Mathématique et Analyse Numérique

In this paper we deal with a semilinear hyperbolic chemotaxis model in one space dimension evolving on a network, with suitable transmission conditions at nodes. This framework is motivated by tissue-engineering scaffolds used for improving wound healing. We introduce a numerical scheme, which guarantees global mass densities conservation. Moreover our scheme is able to yield a correct approximation of the effects of the source term at equilibrium. Several numerical tests are presented to show the...

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