All Years Seminars
[INMA] 2016-03-01 (14:00) : Le PAT technique en INMA
At Euler building (A002)
Speaker :
Huens, Etienne
,
and
François WIELANT (UCL)
Abstract : Explication de quelques-unes de leurs activités.
[INMA] 2016-02-23 (16.30) : A Forward-Backward Quasi-Newton algorithm for minimizing the sum of two nonconvex functions
At CORE (b-135)
Speaker :
Panos Patrinos (ESAT, KULeuven
)
Abstract :
In this talk we consider the problem of minimizing the sum of two nonconvex functions, one of which is smooth and the other prox-bounded and possibly nonsmooth. Such weak requirements on the functions significantly widen the range of applications compared to traditional splitting methods which typically rely on convexity. Our approach is based on the Forward-Backward Envelope (FBE), namely a locally Lipschitz continuous function whose stationary points coincide with those of the original problem. The proposed algorithm exhibits superlinear convergence rates under mild assumptions such as prox-regularity and second-order sufficiency conditions, by using exactly the same oracle information as forward-backward splitting to perform quasi-Newton steps. We show how our theoretical results are backed up by promising numerical simulations on large-scale problems, where the proposed algorithm with limited quasi-Newton updates dramatically outperforms, even in the convex case, popular algorithms like ADMM and the fast proximal gradient method. Joint seminar with the CORE Operations Research seminar series.
[INMA] 2016-02-09 (14:00) : Riemannian geometry applied to EEG-based cerebral interfaces: Challenges and opportunities
At Euler building (A002)
Speaker :
Sylvain Chevallier (Laboratoire d'Ingénierie des Systèmes de Versailles
)
Abstract :
Brain computer interfaces (BCI) allow to interact with a computer without relying on the user's motor capabilities. In rehabilitation and assistive technologies, BCI offer promising solutions to compensate for physical disabilities. A common choice for BCI is to rely on electroencephalogram (EEG) recording for detecting specific brain waves. These brain signals could be recorded with lightweight equipment and have a good temporal resolution but are plagued by several sources of noise (electronic, electrical and biological). Most of the state-of-the-art approaches deal with covariance matrices to reduce the effect of these noise. Indeed, Riemannian geometry has provided a substantial framework for developing new algorithms. Most notably, a straightforward algorithm such as Minimum Distance to Mean yields competitive results when applied with a Riemannian distance. Combined with other approaches, algorithms based on Riemannian geometry have won several machine learning
challenges, outperforming Euclidean-based algorithms. After introducing the basics of electroencephalography and brain computer interface, this talk will explore the benefits brought by the Riemannian distances and their properties.
[INMA] 2016-02-04 (14:00) : From Sand to Silicon Wafers: A Process Systems View of Solar Cell Production
At Euler building (A002)
Speaker :
B. Erik Ydstie (Carnegie Mellon University
)
Abstract :
Solar cell manufacture on global scale is of recent origin and the industrial experience as a whole is limited. Only very recently has the industry grown to the point where intermediate products, such as solar grade silicon, silicon wafers, solar cells and solar panels are commodities with global market potential. Many processes are carried out in batch and difficult to adapt for continuous production. Other processes are in a very early stage of development. This talk reviews the production process for silicon solar cells, starting with quartz and ending with wafers. We highlight challenges relevant to the field of process systems engineering, such as process modeling, design and control. Research work in three distinct areas is reviewed: the application of real time optimization in silicon production, the development of scale-up models for a fluidized bed poly-silicon process and a new process concept for silicon wafer production. We will show how process innovation and the application of process systems engineering tools such as design, optimization and control can reduce cost of solar cells by a factor of two or more.
[INMA] 2015-12-21 (10.30) : La théorie des graphes au service de l'évaluation et de la remédiation
At Euler building (A002)
Speaker :
Laurent Fourny (UCL)
Abstract :
À tous les niveaux de l'enseignement, certains élèves/étudiants éprouvent des difficultés
à apprendre de nouvelles notions. Dans de nombreux cas, la cause principale réside dans une
maîtrise incomplète des prérequis. Il est utile, pour aider les élèves en difficulté, d'établir
un diagnostic focalisé sur les prérequis indispensables, puis de les accompagner dans leur mise
à niveau. Nous verrons comment la théorie des graphes, couplée à la statistique, peut nous aider
à relever ce défi. Nous présenterons également brièvement un site en ligne qui a été développé
sur base de notre recherche.
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+32 10 47 80 36
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