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Small amplitude homogenization applied to models of non-periodic fibrous materials

David Manceau (2007)

ESAIM: Mathematical Modelling and Numerical Analysis

In this paper, we compare a biomechanics empirical model of the heart fibrous structure to two models obtained by a non-periodic homogenization process. To this end, the two homogenized models are simplified using the small amplitude homogenization procedure of Tartar, both in conduction and in elasticity. A new small amplitude homogenization expansion formula for a mixture of anisotropic elastic materials is also derived and allows us to obtain a third simplified model.

Small positive values for supercritical branching processes in random environment

Vincent Bansaye, Christian Böinghoff (2014)

Annales de l'I.H.P. Probabilités et statistiques

Branching Processes in Random Environment (BPREs) ( Z n : n ≥ 0 ) are the generalization of Galton–Watson processes where in each generation the reproduction law is picked randomly in an i.i.d. manner. In the supercritical case, the process survives with positive probability and then almost surely grows geometrically. This paper focuses on rare events when the process takes positive but small values for large times. We describe the asymptotic behavior of ℙ ( 1 ≤ Z n ≤ k | Z 0 = i ) , k , i ∈ ℕ as n → ∞ . More precisely, we characterize the exponential...

Sobre la conveniencia de la existencia de un área de bioestadística.

Antonio Martín Andrés (1996)

Qüestiió

La conveniencia de que todos los profesores de Bioestadística en España se encuentren aglutinados en una única Area de Conocimiento ha sido reiteradamente expuesta por este colectivo en más de una ocasión (I Jornadas de Bioestadística, Barcelona, septiembre de 1984; solicitud al Consejo de Universidades de 28-5-87 y, más recientemente, la de 16-3-95).

Solving Maximum Clique Problem for Protein Structure Similarity

Malod-Dognin, Noël, Andonov, Rumen, Yanev, Nicola (2010)

Serdica Journal of Computing

Computing the similarity between two protein structures is a crucial task in molecular biology, and has been extensively investigated. Many protein structure comparison methods can be modeled as maximum weighted clique problems in specific k-partite graphs, referred here as alignment graphs. In this paper we present both a new integer programming formulation for solving such clique problems and a dedicated branch and bound algorithm for solving the maximum cardinality clique problem. Both approaches have...

Solving Ratio-Dependent Predator-Prey System with Constant Effort Harvesting using Variational Iteration Method

Barari, A., Ghotbi, Abdoul R., Omidvar, M., Ganji, D. D. (2009)

Serdica Journal of Computing

Due to wide range of interest in use of bio-economic models to gain insight into the scientific management of renewable resources like fisheries and forestry,variational iteration method (VIM) is employed to approximate the solution of the ratio-dependent predator-prey system with constant effort prey harvesting.The results are compared with the results obtained by Adomian decomposition method and reveal that VIM is very effective and convenient for solving nonlinear differential equations.

Some mathematical problems arising in heterogeneous insular ecological models.

Sébastien Gaucel, Michel Langlais (2002)

RACSAM

En esta nota se analizan dos modelos matemáticos deterministas planteados en problemas ecológicos causados por la introducción de nuevas especies en ambientes insulares heterogéneos. En el primero desarrollamos un modelo epidemológico con transmisión indirecta del virus por medio del ambiente. En el segundo se introduce un modelo específico de depredador-presa que exhibe la extinción en tiempo finito de las especies. Ambos modelos involucran sistemas de ecuaciones en derivadas parciales con interesantes...

Some necessary and sufficient conditions for the output controllability of temporal Boolean control networks

Yang Liu, Jianquan Lu, Bo Wu (2014)

ESAIM: Control, Optimisation and Calculus of Variations

This paper investigates the output controllability problem of temporal Boolean networks with inputs (control nodes) and outputs (controlled nodes). A temporal Boolean network is a logical dynamic system describing cellular networks with time delays. Using semi-tensor product of matrices, the temporal Boolean networks can be converted into discrete time linear dynamic systems. Some necessary and sufficient conditions on the output controllability via two kinds of inputs are obtained by providing...

Some Parameter Estimation Issues in Functional-Structural Plant Modelling

P.-H. Cournède, V. Letort, A. Mathieu, M. Z. Kang, S. Lemaire, S. Trevezas, F. Houllier, P. de Reffye (2011)

Mathematical Modelling of Natural Phenomena

The development of functional-structural plant models has opened interesting perspectives for a better understanding of plant growth as well as for potential applications in breeding or decision aid in farm management. Parameterization of such models is however a difficult issue due to the complexity of the involved biological processes and the interactions between these processes. The estimation of parameters from experimental data by inverse methods...

Some tracks in air pollution modelling and simulation.

Bruno Sportisse, Jaouad Boutahar, Edouard Debry, Denis Quélo, Karine Sartelet (2002)

RACSAM

In this article we discuss some issues related to Air Pollution modelling (as viewed by the authors): subgrid parametrization, multiphase modelling, reduction of high dimensional models and data assimilation. Numerical applications are given with POLAIR, a 3D numerical platform devoted to modelling of atmospheric trace species.

Some unresolved issued in non-linear population dynamics.

Joe N. Perry (1997)

Qüestiió

The Lyapunov exponent is a statistic that measures the sensitive dependence of the dynamic behaviour of a system on its initial conditions. Estimates of Lyapunov exponents are often used to characterize the qualitative population dynamics of insect time series. The methodology for estimation of the exponent for an observed, noisy, short ecological time series is still under development. Some progress has been made recently in providing measures of error for these exponents. Studies that do not account...

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