Cluster Events

Dear Professors,

The OMOR Cluster and the CERESSEC Research Center have the pleasure to invite you to our next seminar with 

Bahar Yetiş Kara - Bilkent University Industrial Engineering Department 

On Friday, April 10 from 12pm to 1pm

Room : N406

Title: Disaster Resilient Cities: An OR Approach to Disaster Management

Abstract: There have been decades of research in the field of humanitarian logistics, and academics in the field of logistics are becoming more and more interested in it. That being said, we still acquire insight and identify new problems with each disaster. We have also observed various humanitarian logistics applications during Covid-19, e.g. for PCR test sites and vaccination centers. Unfortunately, the recent earthquake in Turkey has led us to re-evaluate the response cycle of disaster management. Close inspection reveals that this response phase actually leads to a variety of new applications of distribution logistics problems. We investigated the potential decision problems and linked these problems with OR literature. During this talk we will explain the general framework and then we will focus on “Fair allocation of In-Kind Donations”

Bio: Bahar Yetis Kara is a Professor in the Department of Industrial Engineering at Bilkent University where she has been a faculty member since 2001. Dr. Kara holds an M.S. and Ph.D. degree from Bilkent University Industrial Engineering Department, and she worked as a Postdoctoral Researcher at McGill University in Canada.

Dr Kara’s current research interests include distribution logistics, humanitarian logistics, hub location and hub network design. Dr. Kara is one of the founders and a member of the executive board of the EURO Working Group on Humanitarian Operations (HOpe). She is also a member of the executive board of Bilkent University and of Turkish OR Society. Dr. Kara editored 4 books and authored/co-authored more than 90 journal and conference papers.

Dr. Kara holds “Best Dissertation Award” given by INFORMS-UPS-SOLA (2001), TUBA-GEBIP (National Young Researchers Career Development Grant) reward (2008), IAP Young Researchers Award (2009), and TÜBİTAK Young Scientist Incentive Award (2010). She is currently co-Editor-in-Chief of Transportation Research- Part B, and working as an associate editor of IIE Transactions, Operations Research, Data Analytics and Logistics, and Socio Economic Planning and Science.

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Daniel KUHN - EPFL 

On Tuesday, April 21 from 12pm to 1pm

Room : N406

Title: On Robust Optimization, Blackouts and the Law

Abstract: Vehicle-to-grid is a concept for mitigating the growing storage demand of electricity grids by using the batteries of parked electric vehicles for providing frequency regulation. Vehicles owners offering frequency regulation promise to charge or discharge their batteries whenever the grid frequency deviates from its nominal value, and they must be able to honor their promises for all frequency deviation trajectories that satisfy certain properties prescribed by EU law. We show that the relevant EU regulations can be encoded exactly in a robust optimization model, and we use this model to demonstrate that the penalties for non-compliance with market rules are currently too low. This suggests that “crime pays” and that the stability of the electricity grid is jeopardized if many frequency providers abuse the system, which could ultimately result in blackouts. The decision problem of a vehicle owner constitutes a non-convex robust optimization problem affected by functional uncertainties. By exploiting the structure of the uncertainty set and exact linear decision rules, however, we can prove that this problem is equivalent to a tractable linear program. Through numerical experiments based on data from France, we quantify the economic value of vehicle-to-grid and elucidate the financial incentives of vehicle owners, aggregators, equipment manufacturers, and regulators. The proposed robust optimization model is relevant for a range of applications involving energy storage.

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Quentin LOUVEAUX - University of Liège 

On Thursday, April 23 from 12pm to 1pm

Room : N406

Title: Sensitivity analysis for linear changes of the constraint matrix of a (mixed-integer) linear program

Abstract: Understanding how the optimal value of an optimisation problem changes when its input data is modified is an old question in mathematical optimisation. In this talk, we investigate the computation of the optimal values of a family of (possibly mixed-integer) linear optimisation problems in which the constraint matrix is subject to linear perturbations controlled by a scalar parameter that varies within a given interval. This is a largely unresolved question with the additional burden that the resulting value function may be largely irregular.

We first discuss the question of complexity of such a model and show in which cases it becomes tractable. We also propose several bounding techniques that provide formal guarantees on the behaviour of the objective value across the entire parameter range. The proposed bounds rely on tools from robust optimisation, Lagrangian relaxation, and ad-hoc reformulations. Each method is assessed in terms of accuracy, precision, and computational performance. Experimental results on a large benchmark set show that the proposed bounding techniques effectively address this class of problems, delivering strong guarantees and good precision.