All Years Seminars
[INMA] 2006-10-24 (09.00 am) : Study day IAP V/22
At Katholieke Universiteit Leuven, College De Valk, Building DV1, Aud. 02.56, Tiensestraat 41, 3000 Leuven
Speaker :
None
Abstract :
[INMA] 2006-10-17 (14.00 pm) : The problem of persistent disturbance rejection via invariant ellipsoids technique
At Euler building
Speaker :
Sergey Nazin (CESAME, previously Institute of Control Science, Moscow)
Abstract :
The problem of disturbance rejection is commonly solved
via dynamic programming technique or l_1 optimal control.
An alternative is to use the invariant set approach, particularly the method
of invariant ellipsoids. The dynamic system under consideration is supposed to
be linear time-invariant and affected by unknown-but-bounded exogenous disturbances.
The influence of these disturbances is measured by the size of invariant ellipsoids. The design
of an optimal state-feedback controller that returns a minimum of the size of the corresponding invariant
ellipsoid for the closed-loop system is reduced to LMI and onedimensional convex minimization. The problem is
considered in continuous and discrete time cases.
[INMA] 2006-10-10 (14.00 pm) : "Coupling between projected matrices and graph matching"
At Euler building
Speaker :
Catherine Fraikin (CESAME)
Abstract :
We consider the problem of finding the optimal
coupling between two projected matrices U_AU and V _BV .
The square matrices A and B are of different dimensions but the isometries U* and V* have
a common column dimension k. The coupling is measured by the real
function c(U, V ) = Rtrace(U_AUV _B_V ), which we maximize of the isometries U_U = V _V = Ik.
This problem can be viewed as an extension of the generalized numerical range of two matrices, which are
now allowed to be of different dimension. Two recursive algorithm are developed to solve the optimization
problem: the first one is based on the Singular Value Decomposition and the second one is a gradient-type
algorithm. We derive also the expressions for the fixed points of the algorithm. This problem can be applied
in the context of graph analysis. We consider here the fundamental task of graph matching which plays a
fundamental role e.g. in pattern recognition. More specifically, we are interested in the problem of matching
directed graphs of different size. In particular, we show how the matching between the two graphs can be
solved by optimally projecting the adjacency matrices in a lower-dimensional subspace.
[INMA] 2006-10-06 (16.15 pm) : "Modélisation par une approche multi-échelles de la mise en forme d'un acier multiphasé à effet TRIP"
At Salle de séminaires TERM, Bâtiment Stevin
Speaker :
Delannay, Laurent
Abstract :
Les aciers multiphasés à effet TRIP présentent un intérêt grandissant, notamment
dans lindustrie automobile où lon exploite leur ductilité et leur résistance afin daugmenter
la quantité dénergie absorbée par la carrosserie lors dun crash. Ces propriétés mécaniques
exceptionnelles sont le résultat de processus micromécaniques relativement complexes. Le comportement
mécanique macroscopique (anisotropie, écrouissage ou retour élastique après mise en forme) ne peut, dès lors,
être prédit que sur base dune approche micro-macro. Le modèle présenté au cours de cet exposé a pour objectifs
de prédire la répartition des déformations entre les phases, le taux de transformation de lausténite en martensite, et les
conséquences de laccommodation plastique autour des particules transformées. Les résultats des simulations numériques
sont confrontés à des mesures expérimentales réalisées à diverses échelles lors de différents modes de chargement.
[INMA] 2006-10-03 (14.00 pm) : "Control and information architectures for formations"
At Euler building
Speaker :
Brian ANDERSON (Australian National University)
Abstract :
Formations of robots, underwater vehicles and autonomous airborne vehicles are
slowly being deployed to tackle problems in both civilian and military spheresbush
fire control, surveillance and the like. In many situations, it is desirable that
the formation members rendezvous, that they move in the same direction or even move
to maintain the formation shape while executing an overall change of location.; Other capabilities are to
change from one shape to another, perhaps to avoid an obstacle, and to split or merge with a different formation.
Living organisms, especially fish and birds, often exhibit this sort of behaviour.
The presentation will consider the types of control, communications and sensing
architecture that allow scalability for formations with many individual agents,
and allow preservation of the formation shape, merging, splitting, or closing ranks
in the event of loss of one or more agents. The scalability requirement imposes a
need for significant decentralization of information and control structures, and,
just as in a formation of birds, no one bird can be expected to watch all other birds and compute its
own trajectory using even partial knowledge of the trajectories of all other individual birds, so the amount
of sensing, communication and control computation by any one agent has to be limited.
Seminars
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secretaire-inma@uclouvain.be
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