Février 2014


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Mardi 4 Février
Heure: 12:00 - 13:30
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: Capacity Planning for Natural Gas Transmission Networks
Description: Jesco Humpola We present a procedure for capacity planning of large-scale real-world
natural gas distribution networks. It decides which combination of
network extensions such as additional pipelines, compressors or valves
should be added to increase the network's capacity or enhance its
operational flexibility. We formulate this as a mixed-integer nonlinear
problem. A sub-problem has different convex reformulations. Hence we use
a combination of linear outer approximation and NLP solution techniques
to solve the MINLP. We show that every dual solution of the convex
reformulations allows to generate capacity inequalities (or cutting
planes) which reduce the overall solution time when added to the
formulation. The dual solution also enables the measurement of
infeasibility level of the scenario. Furthermore we give a primal
heuristic for our model. We present computational results that are
obtained by a special tailored version of the solvers SCIP and IPOPT.
Mardi 18 Février
Heure: 12:30 - 13:30
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: Circuit and bond polytopes in series-parallel graphs
Description: Mathieu Lacroix We describe the circuit polytope in series-parallel graphs. We show the existence of a compact extended formulation for the latter, which inductively provides the description in the original space. As a consequence, using the link between bonds and circuits in planar graphs, we also describe the bond polytope in series-parallel graphs.This is a joint work with S. Borne, R. Grappe, P. Fouilhoux and P. Pesneau.