On Some Estimation Problems Arising in Environmental and Pollution Models

The problem of estimating some unknown parameters in a dynamical system described by stochastic differential equations is discussed. A method of estimation based on non-linear filtering and maximum of likelihood theories is presented. A numerical procedure for the estimation is developed, and the condition for convergence of the method is obtained

Physical modeling of bilabial plosives production

International audienceThe context of this study is the physical modeling of speech production. The first step of our approach is to realize in-vivo measurements during the production of the vowel-consonant-vowel sequence /apa/. This measurements concerns intra-oral pressure, acoustic pressure radiated at the lips and labial parameters (aperture and width of the lips) derived from a high-speed video recording of the subject face. In a second time, theoretical models from speech production literature are under investigation to predict the air flow trough the lips. A model is validated by comparing his predictions with results obtained from measurements on a replica of phonatory system. Then, the same experimental set-up is used to introduce an aerodynamic model of supraglottal cavity expansion. Finally, we achieve numerical simulations of a vowel-bilabial plosive-vowel utterance, by using these models. Simulation results highlight the influence of the cheeks expansion during the production of bilabial plosives

Multi-speed solitary waves of nonlinear Schrödinger systems: theoretical and numerical analysis

International audienceWe consider a system of coupled nonlinear Schrödinger equations in one space dimension. First, we prove the existence of multi-speed solitary waves, i.e solutions to the system with each component behaving at large times as a solitary wave. Then, we investigate numerically the interaction of two solitary waves supported each on one component. Among the possible outcomes, we find elastic and inelastic interactions, collision with mass extraction and reflexion

Considerations on travelling waves in the horn equation and energetic aspects

International audienceThe digital waveguide synthesis of wind resonators and of the vocal tract is based on decompositions into travelling waves. Typical ones are planar waves in straight pipes and spherical waves in conical pipes. However, approximating a bore by cascading such basic segments introduce unrealistic discontinuities on the radius R or the slope R' (with acoustic consequences). It also can generate artificial instabilities in time-domain simulations, e.g. for non convex junctions of cones. In this paper, we investigate the case of the "conservative curvilinear horn equation" for segments such that the flaring parameter R''/R is constant, with which smooth profiles can be built. First, acoustic states that generalize planar waves and spherical waves are studied. Examining the energy balance and the passivity for these travelling waves allows to characterize stability domains. Second, two other definitions of travelling waves are studied: (a) one locally diagonalizes the wave propagation operator, (b) one diagonalizes the transfer matrix of a segment. The propagators obtained for (a) are known to efficiently factorize computations in simulations but are not stable if the flaring parameter is negative. A study in the Laplace domain reveals that propagators (b) are stable for physically meaningful configurations

The strongly confined {S}chrödinger-{P}oisson system for the transport of electrons in a nanowire

International audienceWe study the limit of the three-dimensional Schrödinger-Poisson system with a singular perturbation, to model a quantum electron gas that is strongly confined near an axis. For well-prepared data, which are polarized on the ground space of the transversal Hamiltonian, the resulting model is the cubic defocusing nonlinear Schrödinger equation. Our main tool is a refined analysis of the Poisson kernel when acting on strongly confined densities. In that direction, an appropriate scaling of the initial data is required, to avoid divergent integrals when the gas concentrates on the axis

L'alimentation de l'émeu (Dromaius novaehollandiae)

L'élevage de l'émeu (Dromaius novaehollandiae) a commencé en Australie dans les années 1970 et est apparu en France depuis une dizaine d'années. La maîtrise de l'alimentation est essentielle pour la production de cet animal. La première partie de ce travail présente la zoologie et quelques notions d'élevage de l'émeu. La seconde partie est consacrée aux particularités de l'appareil digestif et à la digestion. Puis, les besoins alimentaires, les apports recommandés et la pratique du rationnement sont abordés avant de présenter les troubles liés à l'alimentation

On a stochastic differential game and its relationship with mixed H2/Hinfini control

Projet META2Résumé disponible dans le fichier PD