Journées Nîmoises d’optimisation de forme

Session

Exposé

15 juin 2026, 14:00

Amphi A3 (Fort Vauban, Nîmes)

7. Une inégalité isopérimétrique quantitative en $\mathbb{R}^3$

Gisella Croce

15/06/2026 14:00

Dans ce séminaire nous allons étudier un problème de stabilité pour l'inégalité isopérimétrique dans $\mathbb{R}^3$, faisant intervenir une asymétrie de type Hausdorff. Pour un corps convexe $F \subset \mathbb{R}^3$ de volume $4\pi/3$ (c'est-à-dire le volume de la boule unité dans l'espace), nous considérons la fonctionnelle
$$ Q^*(F) :=...

4. Régularité et unicité des minima $BV$

Pierre Bousquet

15/06/2026 14:50

Les minima de problèmes de calcul des variations scalaires posés dans $BV$ sont généralement discontinus et sont rarement uniques, lorsque l'intégrande associé est supposé convexe (mais pas nécessairement strictement convexe). En l'absence de toute hypothèse de croissance linéaire, on montre comment des conditions géométriques ou de régularité sur le domaine d'intégration ou la condition au...

2. Lemme de Gehring pour les équations cinétiques et ultraparaboliques

Jessica Guerand

15/06/2026 16:10

Le lemme de Gehring affirme qu’une fonction satisfaisant une inégalité de Hölder inverse sur des sous-domaines possède une meilleure intégrabilité. Introduit à l’origine par Gehring dans le cadre de problèmes ouverts en théorie des applications quasiconformes, ce résultat a depuis été adapté à l’étude de gain d'intégrabilité des gradients de solutions d’équations elliptiques et...

3. Boundary Regularity of a Fourth Order Alt–Caffarelli Problem

Jimmy Lamboley

16/06/2026 09:00

In this talk, we will present recent results obtained with Mickaël Nahon on a free boundary problem involving the bi-laplace operator. This can be seen as a higher-order analogue of the classical Alt–Caffarelli free boundary problem from 1981. This kind of results can be applied to different shape optimization problems, including the minimization of the first buckling eigenvalue under area...

11. A Unified Semi-Smooth Newton--PDAS Framework for Finite-Strain Contact with SMA-Inspired Transformation

Thuong Nguyen

16/06/2026 09:50

In this work, we propose a unified computational framework for large-strain dynamic contact in shape-memory-alloy (SMA) structures, with application to stent deployment in an artery-like environment. The model couples persistent unilateral contact and Coulomb friction at interfaces with finite-strain SMA inelastic transformations. A key feature is that both interface constraints and...

5. Topological derivative for Kirchhoff-Love shells

Samuel Amstutz

16/06/2026 10:50

Joint work with Michael Gfrerer (TU Graz)

I will present a recent work dedicated to the topological sensitivity analysis for the linear Kirchhoff-Love shell model in the case of an elastic inclusion. It extends prior works on plates, but significant additional difficulties are due to curvature, in a more or less direct way. In particular, the coupling between the bending and in-plane...

12. Reverse Isoperimetric Inequalities

Zakaria Fattah

16/06/2026 11:40

The classical isoperimetric inequality gives a sharp lower bound on the perimeter of a domain with fixed volume, with equality attained by the ball. Reverse isoperimetric inequalities ask the opposite question: how large can the perimeter or surface area be under a volume constraint? Since this problem is generally ill-posed without additional assumptions, one has to impose geometric...

6. A theorem by Goldstein and Vodopyanov and its generalizations

Reza Pakzad

16/06/2026 14:00

A theorem by Goldstein and Vodopyanov from 70s states the following: Let $\Omega \subset {\mathbb R}^n$ be a domain and $u : \Omega \to {\mathbb R}^n$  a deformation of $W^{1,n}$ regularity. If the Jacobian determinant ${\rm det}\, Du$ is positive almost everywhere, then $u$ is continuous. We will discuss a few recent generalizations of this theorem to other function spaces (such as fractional...

13. Stable full-field simulation of a multiscale elliptic equation by means of Quantized Tensor Trains

Anas El Hachimi

16/06/2026 14:50

This work addresses the numerical approximation of elliptic differential equations in heterogeneous media, with a particular focus on high-resolution discretizations and large computational challenges. Our main motivation is handling multiscale problems with oscillating coefficient. The proposed framework relies on tensor-based techniques, in particular Quantized Tensor Train (QTT)...

10. Homogenization of singular SPDEs

Nicolas Clozeau

16/06/2026 15:50

I will present an ongoing joint research project with Harprit Singh (postdoctoral researcher at the University of Vienna) on the stochastic homogenization of parabolic singularstochastic PDEs (singular SPDEs) in correlated media. Our goal is to understand the large-scale behavior of such equations, that is, to derive an effective equation, for parabolic singularSPDEs with oscillatory random...