Prochains exposés

SPOT 63– Lundi 1 Juillet 2019 –  Amphi des thèses ENSEEIHT

14h – Bachir El Khadir – Princeton Univ, USA

Power and Limitations of Sum of Squares Programming for Stability Analysis of Dynamical Systems

We study the power and limitations of sum of squares optimization and semialgebraic Lyapunov functions for proving asymptotic stability of polynomial dynamical systems. We give the first example of a globally asymptotically stable polynomial vector field with rational coefficients that does not admit a polynomial (or even analytic) Lyapunov function in any neighborhood of the origin. We show, however, that if the polynomial vector field is homogeneous, then its asymptotic stability is equivalent to existence of a rational Lyapunov function whose inequalities have sum of squares proofs. This statement generalizes the classical result in control on the equivalence between asymptotic stability of linear systems and existence of a quadratic Lyapunov function satisfying a certain linear matrix inequality.

15h – Tillmann Weisser – Los Alamos Nat Lab, USA

Relaxations and Uncertainty Quantification for the Power Grid

Optimal scheduling power generation such that the energy needs in the grid are met everywhere and at all time is a challenging problem. In particular due to the significant increase of renewable energies in the last years, the search for a global optimal operating point has become more difficult because the generation capacities change over time and often are not entirely predictable. In this talk I address this problem in two ways: First, I will talk about relaxations of the AC Power Flow problem which are used to detect whether locally found solutions are globally optimal. In my current research we are trying to strengthen these relaxations without increasing their computational cost to an unacceptable level.  In the second half, I propose a strategy to avoid solving expensive robust or stochastic programs online by precomputing deterministic approximations.

Comité local d’organisation

Cf un glossaire expliquant ces sigles et affiliations du système universitaire toulousain.

 Fréquence et structure

Une séance par mois environ, avec deux conférenciers chaque fois (deux conférences de type différent : une orientée fondements et une orientée applications, un conférencier de l’environnement toulousain et un conférencier extérieur, un conférencier du milieu académique et un conférencier du milieu de l’industrie et des services, etc.).

Horaire habituel : le lundi après-midi de 14h à 16h.


Sauf indication contraire, à l’amphithéâtre des (SPOT-) thèses à l’ENSEEIHT (N7), 2 rue Charles Camichel, 31000 Toulouse  (métro B, François Verdier). Attention, présentez-vous au poste de garde afin d’accéder au site.