Title: Solution approaches for a class of r-allocation hub location problems
Date: 28 November 2025, Friday
Time: 13:30-14:30
Place: EA409
Abstract: For many transportation and telecommunication companies, providing equitable service to clients is an important priority, which can be achieved by solving p-hub center problems. However, due to NP-hard nature of the p-hub center problem, tackling realistic instances of such problems in reasonable time is not an easy task at all. This study addresses the uncapacitated r-allocation p-hub center problem, and proposes two solution approaches for that. The first is a Benders decomposition algorithm that obtains proven optimal solutions for medium and large instances, whereas the second is a matheuristic approach that is able to solve very large instances of the problem in short computational time. The matheuristic algorithm is composed of two components one for determining the location of hubs and the other for allocation of non-hub nodes to the hubs. Both components use Benders decomposition for solving the related problems, and are run in an iterative manner to guide the search in converging to high quality solutions (optimal in most cases). The efficiency and effectiveness of the proposed algorithms is demonstrated by conducting a comprehensive set of computational experiments using different test instances with up to more than 400 nodes. Obtained results indicate the superiority of the proposed methods compared to the state-of-the art, both in terms of solution quality and computational time.
Bio: Nader Ghaffarinasab is an assistant professor at the Department of Industrial Engineering at Middle East Technical University (METU). Before joining METU, he worked as a faculty member in the Department of Industrial Engineering at University of Tabriz between 2014 and 2023. He has received his Ph.D. degree from Iran University of Science and Technology (IUST) in 2014. During his Ph.D. studies, he spent six months as a visiting student at the Department of Industrial Engineering and Innovation Sciences at Eindhoven Institute of Technology. His main research interests include facility location, vehicle routing and transport economics, large-scale optimization, and heuristic methods.