Optimality certificates for convex minimization and Helly numbers

We consider the problem of minimizing a convex function over a subset of R^n that is not necessarily convex (minimization of a convex function over the integer points in a polytope is a special case). We define a family of duals for this problem and show that, under some natural conditions, strong duality holds for a dual problem in this family that is more restrictive than previously considered duals.Comment: 5 page

Coupled visco-mechanical and diffusion void growth modelling during composite curing

Most critical processing step during long fiber reinforced epoxy matrix composite laminate manufacturing is the polymerization stage. If not optimized, it gives birth to defects in the bulk material, such as voids. These defects are considered as possible sources of damage in the composite parts. The aim of this work is to model the evolution of void growth in thermoset composite laminates after ply collation (autoclave processes) or resin impregnation (RTM, LCM process). A coupled mechanical and diffusion model is presented to better predict the final void size at the end of polymerization. Amongst the parameter investigated, onset of pressure application and diffusive species concentration where found to have a major effect on void size evolution during curing process

Model-free based water level control for hydroelectric power plants

International audienceAutomatic water level control methods for open channels have difficulties to keep good performances for a large range of flow and significant unknown disturbances. A new concept called "model-free control" is applied in this paper for hydroelectric run-of-the river power plants. To modulate power generation, a level trajectory is planned for cascaded power plants. Numerous dynamic simulations show that with a simple and robust control algorithm, the set-point is followed even in severe operating conditions

Vers une commande sans mod\`ele pour am\'enagements hydro\'electriques en cascade

A new concept called "Model-Free Control" is applied to hydroelectric run-of-the river power plants, with severe constraints and operating conditions. Numerous computer simulations display excellent results, which are obtained thanks to simple and robust algorithms

Une "commande sans modèle" pour aménagements hydroélectriques en cascade

International audienceOn aborde, par la "commande sans modèle", la régulation du niveau d'eau dans un aménagement hydraulique, soumis à de fortes contraintes, pour produire de l'électricité. Les nombreuses simulations numériques fournissent d'excellents résultats, obtenus grâce à des algorithmes robustes et simples

Concentration of symmetric eigenfunctions

In this article we examine the concentration and oscillation effects developed by high-frequency eigenfunctions of the Laplace operator in a compact Riemannian manifold. More precisely, we are interested in the structure of the possible invariant semiclassical measures obtained as limits of Wigner measures corresponding to eigenfunctions. These measures describe simultaneously the concentration and oscillation effects developed by a sequence of eigenfunctions. We present some results showing how to obtain invariant semiclassical measures from eigenfunctions with prescribed symmetries. As an application of these results, we give a simple proof of the fact that in a manifold of constant positive sectional curvature, every measure which is invariant by the geodesic flow is an invariant semiclassical measure.Comment: 8 page