All Years Seminars
[INMA] 2010-04-27 (14.00) : Occupation measures and LMI formulation of piecewise affine optimal control design problems
At Euler building
Speaker :
Didier HENRION (LAAS-CNRS, University of Toulouse, France, and Faculty of Electrical Engineering, Czech Technical University in Prague, Czech Republic )
Abstract :
After recalling the mathematical framework of
occupation measures for nonlinear dynamical systems control,
we show how linear matrix inequalities (LMI) can be used
to solve computationally the corresponding generalized
problem of moments. We illustrate these ideas first
on a simple linear quadratic regulator design problem,
and then on a less trivial piecewise affine optimal control
problem for which we know analytically the solution
of the Hamilton-Jacobi-Bellman equation. This is joint work
with Luis Rodrigues, Concordia University, Montreal, Canada.
[INMA] 2010-04-20 (14.00) : The brain accounts for 3D eye and head kinematics in the visuomotor transformation of velocity signals in manual tracking
At Euler building
Speaker :
Leclercq, Guillaume
Abstract :
Visually guided arm movements are common actions carried out each day in our everyday life. When performing visually guided arm movements,
the brain needs to transform the visual information (the tennis ball, an obstacle) into an appropriate motor plan for the arm (i.e. a command to give
to the arm's muscles). Here, we investigated if the brain accounts for the 3D eye position, 3D head position and 3D eye velocity in the visuomotor
transformation of velocity signals for manual tracking movements. A visuomotor transformation model taking into account the complete 3D eye-head-shoulder
kinematics was built using dual quaternions. To test model predictions, human subjects performed manual tracking movements in different eye-head-shoulder
configurations, either static or dynamic. We compared the arm initial open-loop direction with the predictions provided by the model. Results show that the brain
uses internal 3D eye and head position as well as eye velocity signals to account for the eye-head-shoulder kinematics in the visuomotor transformation of velocity
signals for manual tracking movements.
[INMA] 2010-04-13 (14.00) : Quality meshing of medical geometries with harmonic map
At Euler building
Speaker :
Emilie
MARCHANDISE (CESAME)
Abstract :
This work describes an automatic approach to recover a high quality surface mesh from low-quality
or oversampled inputs (STL-files) obtained from medical imaging through classical segmentation
techniques. The approach combines a robust method of parametrization based on harmonic maps
with a recursive call to a multi-level edge partitioning software. By doing so, we are able to get rid
of the topological and geometrical limitations of harmonic maps. The overall remeshing procedure
is implemented, together with the ïnfinite element discretization procedure required for computing
harmonic maps, in the open-source mesh generator Gmsh. We show that the proposed method
produces high quality meshes and we highlight the benefits of using those high quality meshes for
biomedical simulations.
[INMA] 2010-04-06 (14.00) : Polynomial Chaos Expansion in Reliability Analysis and Robust Optimisation
At Euler building
Speaker :
Zein, Samih
Abstract :
The Polynomial Chaos Expansion (PCE) is an efficient numerical method for relating
the output of a nonlinear system with the uncertainty in its input parameters.
The output can be approximated with a multidimensional polynomial function using
the so called PCE. Numerically, such approximation can be obtained using a linear
regression with an adequate design of experiments. In this presentation, a review
is given on the PCE principle and its application in reliability analysis and robust
optimisation. Then, an optimization algorithm is proposed that seeks the best design
of experiments in the D-optimal sens for the PCE. This algorithm is based on the heuristic
optimisation and the Fedorov exchange algorithm and is adapted to the specific case of the
polynomial chaos expansion. We will conclude the presentation with a brief overview of the
integration of a PCE method into an industrial optimization platform and task manager."
[INMA] 2010-03-23 (14.00) : One path is not enough anymore
At Euler building
Speaker :
Olivier
BONAVENTURE (UCL-INGI)
Abstract :
The Internet was designed with the assumption that there was one path
between a pair of communicating hosts. The TCP congestion control scheme
was added in the late 1980s to avoid congestion collapse on bottleneck
links. The growth of multihoming, both at the enterprise/campus network
level and at the host level with multiple wireless interfaces,
completely changes the situation since there are now several useable
paths between communicating hosts. In this talk, I'll survey the broad
implications of this change on the network, transport and application
layers of the Future Internet.
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