Un algorithme d'identification de frontières soumises à des conditions aux limites de Signorini
Un algorithme d'identification de frontières soumises à des conditions aux limites de Signorini
This work deals with a non linear inverse problem of reconstructing an unknown boundary γ, the boundary conditions prescribed on γ being of Signorini type, by using boundary measurements. The problem is turned into an optimal shape design one, by constructing a Kohn & Vogelius-like cost function, the only minimum of which is proved to be the unknown boundary. Furthermore, we prove that the derivative of this cost function with respect to a direction θ depends only on the state u0, and not...
Une approche géométrique du contrôle optimal de l’arc atmosphérique de la navette spatiale
L’objectif de ce travail est de faire quelques remarques géométriques et des calculs préliminaires pour construire l’arc atmosphérique optimal d’une navette spatiale (problème de rentrée sur Terre ou programme d’exploration de Mars). Le système décrivant les trajectoires est de dimension 6, le contrôle est l’angle de gîte cinématique et le coût est l’intégrale du flux thermique. Par ailleurs il y a des contraintes sur l’état (flux thermique, accélération normale et pression dynamique). Notre étude...
Une approche géométrique du contrôle optimal de l'arc atmosphérique de la navette spatiale
The aim of this article is to make some geometric remarks and some preliminary calculations in order to construct the optimal atmospheric arc of a spatial shuttle (problem of reentry on Earth or Mars Sample Return project). The system describing the trajectories is in dimension 6, the control is the bank angle and the cost is the total thermal flux. Moreover there are state constraints (thermal flux, normal acceleration and dynamic pressure). Our study is mainly geometric and is founded on the...
Unification of the abstract duality scheme
Upper and lower bounds for minimal norm problems under linear constraints
Upper bounds on the solution of coupled algebraic Riccati equation.
Use of semidefinite programming for solving the LQR problem subject to rectangular descriptor systems
This paper deals with the Linear Quadratic Regulator (LQR) problem subject to descriptor systems for which the semidefinite programming approach is used as a solution. We propose a new sufficient condition in terms of primal dual semidefinite programming for the existence of the optimal state-control pair of the problem considered. The results show that semidefinite programming is an elegant method to solve the problem under consideration. Numerical examples are given to illustrate the results.