Domino tilings and related models: space of configurations of domains with holes

We first prove that the set of domino tilings of a fixed finite figure is a distributive lattice, even in the case when the figure has holes. We then give a geometrical interpretation of the order given by this lattice, using (not necessarily local) transformations called {\em flips}. This study allows us to formulate an exhaustive generation algorithm and a uniform random sampling algorithm. We finally extend these results to other types of tilings (calisson tilings, tilings with bicolored Wang tiles).Comment: 17 pages, 11 figure

Interaction of a glow discharge with an ion beam

The aim is to derive a fluid model, of hydrodynamic/diffusion type, describing the interaction of a glow discharge with an ion beam at atmospheric pressure

Diffusion limits of the Lorentz model: Asymptotic preserving schemes

This paper deals with the diffusion limit of a kinetic equation where the collisions are modeled by a Lorentz type operator. The main aim is to construct a discrete scheme to approximate this equation which gives for any value of the Knudsen number, and in particular at the diffusive limit, the right discrete diffusion equation with the same value of the diffusion coefficient as in the continuous case. We are also naturally interested with a discretization which can be used with few velocity discretization points, in order to reduce the cost of computation