All Years Seminars
[INMA] 2007-11-27 (14.00) : "Thermodynamics of Linear Systems"
At Euler building
Speaker :
Delvenne, Jean-Charles
Abstract :
We rigorously derive the main results of thermodynamics,
including Carnot's theorem, in the framework of
time-varying linear systems.
[INMA] 2007-11-20 (14.00) : Opinion dynamics on complex networks
At Euler building
Speaker :
Lambiotte, Renaud
Abstract :
In the last years, several models have been introduced in order to
model the way opinions diffuse in society and consensus is (or not)
reached. In this talk, I'll first focus on the Voter model and on the
Vacillating Voter model [1] and show that their features may be
radically different depending on the underlying topology, i.e. the
social network, on which the dynamics takes place. I will also focus
on the Majority Rule and the Unanimity Rule [2], and discuss in
detail the role played by the degree heterogeneity [3] and the
presence of communities [4,5] in the network.
[INMA] 2007-11-13 (14.00) : "Optimal control techniques for fast nonlinear systems"
At Euler building
Speaker :
Jean-Baptiste COULAUD
(CESAME)
Abstract :
"Several software packages have been designed in the past few years to bring
the efficiency of constrained optimal control to nonlinear systems with fast dynamics,
like robots. One of them (NTG), uses a spline description of the trajectories and reduces
the optimal control problem to an optimization one, taking advantage of dynamics inversion based on
differential flatness. The talk will focus on these techniques and some proposals for improvements
and adaptations."
[INMA] 2007-11-08 (16.30) : Colloquium CESAME/MAPA "Les khipus non décryptés des Incas : les mathématiques à l'aide de l'archéologie"
At Auditoire Ch.-J de La Vallée Poussin (cycl 01)
Speaker :
Jean-Jacques QUISQUATER
( ELEC-DICE )
Abstract :
Un sujet unissant archéologie, mathématique, informatique et linguistique.
Durant près d'un siècle (1438-1534), l'empire inca s'est étendu jusqu'à atteindre plus de 4000 km de long.
Cet empire fut administré avec rigueur à partir de la capitale Cuzco avec une langue, le Quechua, dont il existe près de 700 dialectes.
Il y a un mystère non élucidé : les Incas n'avaient pas d'écriture, contrairement aux Mayas, par exemple, leurs voisins du Nord, des siècles auparavant.
Il y a un autre mystère : les Incas utilisaient des cordelettes et des noeuds en un assemblage à la fois fort complexe et très structuré, des khipus, aussi notés quipus.
Nous décrirons ces khipus en détail (ils en restent plus de 600 disséminés dans des musées). A l'aide des mathématiques, des statistiques,
de l'informatique, etc, nous montrerons comment des chercheurs essaient aujourd'hui de décrypter ces khipus, et, de là, retrouver, peut-être,
les traces d'une écriture inconnue ...
[INMA] 2007-10-30 (14.00) : "Nonlinear modal analysis of structural systems"
At Euler building
Speaker :
Gaëten KERSCHEN
( ULg )
Abstract :
The concept of nonlinear normal modes (NNMs) is discussed in this presentation.
The fundamental properties of NNMs are first described and illustrated using simple examples.
Their usefulness for modal analysis of nonlinear vibrating structures is the discussed.
Because there is virtually no application of the NNMs to large-scale engineering structures, several aspects
that might drive their development in the future are also highlighted. Specifically, we support that (i) numerical
methods for the continuation of periodic solutions pave the way for an effective and practical
computation of NNMs, and (ii) time-frequency analysis is particularly suitable for the analysis of the resulting dynamics.
Seminars
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