All Years Seminars
[INMA] 2006-12-14 (16.30pm) : Colloquium CESAME/MAPA "Geometric Knot theory"
At Auditoire Euler
Speaker :
John Sullivan (T.U. Berlin)
Abstract :
Geometric knot theory is the study of geometric properties of
space curves that derive from their topological knottedness.
Perhaps the most famous result is the Fary/Milnor theorem relating
total curvature to bridge number, but the field can be dated back
to work of Pannwitz on quadrisecant lines for knots. There has been
a surge of interest in geometric knot theory over the past decade,
partly due to biophysical applications to the shapes of knotted
polymers like DNA molecules. One interesting problem with some
surprising answers asks for the shapes of knots and links tied
tight in rope of fixed thickness. We will survey recent results on
this so-called ropelength problem, as well as some new strengthened
versions of the theorems of Pannwitz and Fary/Milnor.
[INMA] 2006-12-05 (14.00 pm) : "How to track an agent in a network ?"
At Euler building
Speaker :
Jungers, Raphaël M.
Abstract :
Consider an agent moving from node to node in a directed graph
whose edges are colored. The agent knows the colored graph but does not know where he is,
and he tries to reconstruct his position in the graph based on the color sequence he observes.
We say that an edgecolored directed graph is observable if there is some observation time length
after which, whatever the color sequence observed, the agent is able to determine his position in the
graph and is able to do so for all subsequent times. This framework leads to several interesting questions:
How can the agent deduce his position from the sequence of colors he observes? Will he be able to do so in all case?
How to assign colors in a graph so that he will be able to compute his position efficiently?
This problem is related with well studied problems in several fields
of engineering, including Hidden Markov Models, Discret Events Systems in control theory, and
Local Automata in the theory of automata and formal languages . We review and connect the main results
arising from those areas, and present some new complexity results on the design question.
[INMA] 2006-11-28 (14.00 pm) : "Modélisation et contrôle du trafic autoroutier"
At Euler building
Speaker :
Bertrand HAUT (CESAME)
Abstract :
Avec la hausse constante du nombre de véhicules, les problèmes
de congestion sur les autoroutes deviennent de plus en plus préoccupants.
Il n'est pas toujours possible de construire de nouvelles routes et cela peut même
s'avérer contre-productif. C'est pourquoi il est nécessaire de développer de nouvelles
stratégies afin d'utiliser au mieux le réseau existant. Ces stratégies de contrôle ne peuvent être
développées sans se baser sur une modélisation correcte du phénomène. Au cours de cette présentation,
une famille de modèle capable de reproduire la majorité des phénomènes observés sur autoroute sera présentée.
Sur base de cette modélisation, quelques moyens de contrôle seront discutés.
[INMA] 2006-11-21 (14.00 pm) : "Closed-loop identification of MIMO systems: A new look at identifiability and experiment design"
At Euler building
Speaker :
Ljubisa Miskovic (Ecole Polytechnique Fédérale de Lausanne, Suisse/CESAME)
Abstract :
In this talk, the identifiability of closed loop systems is re-examined
with a double objective: (i) clarify the differences between already existing
definitions of identifiability and propose one that is both realistic and workable;
(ii) establish conditions on the controller and on the external excitation that guarantee
identifiability in the case of multi-input multi-output (MIMO) systems. Furthermore, the
following question is addressed: is it necessary that all reference inputs be excited in a MIMO
system if a certain accuracy level is desired for the parameter covariance matrix?
[INMA] 2006-11-17 (16.15 pm) : "Solveurs AMG (Algebraic MultiGrid) et multifrontaux pour points de selle et matrices non symétriques"
At Salle de séminaires TERM, Bâtiment Stevin
Speaker :
Jean-Marie Marchal (CAE Consulting)
Abstract :
Seminars
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