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Non-Markovian quadratic forms obtained by homogenization

Marc Briane — 2003

Bollettino dell'Unione Matematica Italiana

This paper is devoted to the asymptotic behaviour of quadratic forms defined on L 2 . More precisely we consider the Γ -convergence of these functionals for the L 2 -weak topology. We give an example in which some limit forms are not Markovian and hence the Beurling-Deny representation formula does not hold. This example is obtained by the homogenization of a stratified medium composed of insulating thin-layers.

Is it wise to keep laminating ?

Marc BrianeVincenzo Nesi — 2004

ESAIM: Control, Optimisation and Calculus of Variations

We study the corrector matrix P ϵ to the conductivity equations. We show that if P ϵ converges weakly to the identity, then for any laminate det P ϵ 0 at almost every point. This simple property is shown to be false for generic microgeometries if the dimension is greater than two in the work Briane et al. [Arch. Ration. Mech. Anal., to appear]. In two dimensions it holds true for any microgeometry as a corollary of the work in Alessandrini and Nesi [Arch. Ration. Mech. Anal. 158 (2001) 155-171]. We use this...

Is it wise to keep laminating?

Marc BrianeVincenzo Nesi — 2010

ESAIM: Control, Optimisation and Calculus of Variations

We study the corrector matrix P ε  to the conductivity equations. We show that if P ε  converges weakly to the identity, then for any laminate det P ε 0 at almost every point. This simple property is shown to be false for generic microgeometries if the dimension is greater than two in the work Briane [, to appear]. In two dimensions it holds true for any microgeometry as a corollary of the work in Alessandrini and Nesi [ (2001) 155-171]. We use this property of laminates to prove that, in any...

Estimate of the pressure when its gradient is the divergence of a measure. Applications

Marc BrianeJuan Casado-Díaz — 2011

ESAIM: Control, Optimisation and Calculus of Variations

In this paper, a W - 1 , N ' estimate of the pressure is derived when its gradient is the divergence of a matrix-valued measure on N , or on a regular bounded open set of  N . The proof is based partially on the Strauss inequality [Strauss, 23 (1973) 207–214] in dimension two, and on a recent result of Bourgain and Brezis [ 9 (2007) 277–315] in higher dimension. The estimate is used to derive a representation result for divergence free distributions which read as the divergence of a measure, and to prove an...

Homogenization of systems with equi-integrable coefficients

Marc BrianeJuan Casado-Díaz — 2014

ESAIM: Control, Optimisation and Calculus of Variations

In this paper we prove a H-convergence type result for the homogenization of systems the coefficients of which satisfy a functional ellipticity condition and a strong equi-integrability condition. The equi-integrability assumption allows us to control the fact that the coefficients are not equi-bounded. Since the truncation principle used for scalar equations does not hold for vector-valued systems, we present an alternative approach based on an approximation result by Lipschitz functions due to...

Estimate of the pressure when its gradient is the divergence of a measure. Applications

Marc BrianeJuan Casado-Díaz — 2011

ESAIM: Control, Optimisation and Calculus of Variations

In this paper, a W - 1 , N ' estimate of the pressure is derived when its gradient is the divergence of a matrix-valued measure on N , or on a regular bounded open set of  N . The proof is based partially on the Strauss inequality [Strauss, (1973) 207–214] in dimension two, and on a recent result of Bourgain and Brezis [ (2007) 277–315] in higher dimension. The estimate is used to derive a representation result for divergence free distributions which read as the divergence of...

Which electric fields are realizable in conducting materials?

Marc BrianeGraeme W. MiltonAndrejs Treibergs — 2014

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

In this paper we study the realizability of a given smooth periodic gradient field ∇ defined in R, in the sense of finding when one can obtain a matrix conductivity such that ∇ is a divergence free current field. The construction is shown to be always possible locally in R provided that ∇ is non-vanishing. This condition is also necessary in dimension two but not in dimension three. In fact the realizability may fail for non-regular gradient fields, and in general the conductivity cannot be both...

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