All Years Seminars
[INMA] 2007-09-18 (14.00) : "Solution of a distributed linear system stabilisation problem"
At Euler building
Speaker :
Brian ANDERSON (Australian National University)
Abstract : This talk deals with the following problem. Given a real square matrix A, when is there a real diagonal matrix L such that LA has all its eigenvalues with negative real part, and how may such a matrix be constructed? This problem arose in studying how to construct decentralized feedback control laws used by agents in a two-dimensional formation, where the shape of the formation is to be preserved through a sufficient number of agent pairs each maintaining a prescribed separation, and the open-loop system may be unstable. A sufficient condition (which in a sense is not 'far' from a necessary condition) is obtained, involving the principal minors of A, and it is fulfilled in the application problem. Some associated open problems are also exposed.
[INMA] 2007-07-05 (11.00) : Une approche variationnelle de Steklov-Poincaré pour la complétion de données
At Euler building
Speaker :
Henda El Fekih
(Ecole Nationale d'Ingénieur de Tunis, LAMSIM)
Abstract :
Le problème de complétion de données consiste à reconstituer des données sur le bord total du domaine à partir
de mesures partielles et surdéterminées.
Comme application, on peut citer l'EEG (Electro-Encéphalo-Graphie) pour détecter les points sources générant les crises d'épilepsie.
Le sujet principal de cet exposé est d'établir que ce problème (dit de Cauchy) est instable, et possède
une formulation variationnelle qui peut être mise sous forme d'une équation (variationnelle) pseudo-différentielle,
posée sur la frontière incomplète, et définie à l'aide d'un opérateur de type Steklov-Poincaré qui est compact.
Cette approche nous permet d'utiliser les méthodes classiques d'éléments finis pour la résolution du problème de complétion de données.
[INMA] 2007-06-12 (14.00) : Switching Control for Multi-Agent Formation Maintenance
At Euler building
Speaker :
Fidan, B.
Abstract :
This talk is on maintenance of formation geometries of a class of autonomous multi-agent systems
moving in formation, namely persistent formations, using decentralized switching control schemes.
In a persistent formation, the formation shape is maintained during any continuous motion via a set
of constraints on each agent to keep its distances from a pre-specified group of other neighboring agents
constant. The talk consists of several cohesive motion control problems for persistent autonomous formations.
The aim in the first two of these problems is designing distributed control schemes for moving a given persistent
formation with specified initial position and orientation to arbitrary desired final position and orientation without deforming
the shape of the formation during the motion, one for obstacle-free environments and the other for regions with obstacles.
The third problem is on obstacle avoidance and rendezvous of a team of three unmanned aerial vehicles (UAVs) around a common
target. In the fourth problem, a similar team of three UAVs is required to survey a region of interest in formation following a specified path.
The last problem investigated using switching control approaches is acquisition/maintenance of desired inter-agent distances for
non-hierarchical autonomous multi-agent platoons using a decentralized scheme in the existence of measurement noises,
which cause instability problems when classical controllers are used.
[INMA] 2007-05-15 (14.00) : Statistical analysis of shapes of curves and surfaces
At Auditoire Euler
Speaker :
Srivastava, A.
Abstract :
We introduce a statistical framework for studying shapes of curves
and surfaces with applications in 2D and 3D image analysis. An important
tool for comparing and analyzing shapes is to
compute geodesics on shape spaces, under the chosen Riemannian
metrics. I will show two methods -- shooting and
path-straightening -- to compute geodesics on these spaces. Using
geodesics, one can define and compute sample statistics, impose
probability distributions, and study hypothesis testing involving
shapes. The case of analyzing shapes of surfaces, e.g. facial surfaces,
is much more difficult. Our approach is to represent a surface as an
indexed collection of curves and to extend ideas from curve analysis
to perform surface analysis. I will demonstrate this using a database
of facial surfaces.
[INMA] 2007-05-11 (16.15pm) : "Modélisation de l'évolution de texture dans les aciers à effet TWIP"
At Salle séminaire TERM, Bâtiment Stevin
Speaker :
Maxime Melchior (CESAME)
Abstract :
Seminars
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L4.05.01
Avenue Georges Lemaître, 4
+32 10 47 80 36
secretaire-inma@uclouvain.be
Mon – Fri 9:00A.M. – 5:00P.M.
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