Endüstri Mühendisliği Ana Bilim Dalı Tez Koleksiyonu

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Browsing Endüstri Mühendisliği Ana Bilim Dalı Tez Koleksiyonu by Author "Kayışoğlu, Betül"

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    Development of models and solution methodologies for tree of hubs location and arc capacitated hub location problems
    (Abdullah Gül Üniversitesi Fen Bilimleri Enstitüsü, 2022) Kayışoğlu, Betül; AGÜ, Fen Bilimleri Enstitüsü, Endüstri Mühendisliği Ana Bilim Dalı
    In this dissertation, we study two different extensions to hub location problems, namely, Multiple Allocation Tree of Hubs Location Problem (MATHLP) that result from incorporating a tree topology requirement for the hub network and Multiple Allocation Arc Capacitated Hub Location Problem (MACHLP) that result from imposing capacities on the arcs. We consider both problems in a multiple allocation framework and try to minimize total flow cost by locating p hubs. Unlike most studies in the literature that use complete networks with costs satisfying the triangle inequality to formulate the problems, we define the problems on non-complete networks and develop a modeling approach that does not require any specific cost and network structure. Our proposed approach provides more flexibility in modeling several characteristics of reallife hub networks. We solve the proposed models using CPLEX-based algorithm and Gurobi-based algorithm with NoRel heuristic. For MATHLP, we develop Benders decomposition-based heuristic algorithms and for MACHLP, we develop a heuristic algorithm based on simulated annealing. We conduct computational experiments using problem instances defined on non-complete networks with up to 500 and 400 nodes for MATHLP and MACHLP respectively. The results indicate that the proposed solution methodologies are especially effective in finding good feasible solutions for large instances.