P-hub maximal covering problem and extensions for gradual decay functions

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Author
Peker, Meltem
Advisor
Kara, Bahar Y.
Date
2013Publisher
Bilkent University
Language
English
Type
Thesis
Metadata
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http://hdl.handle.net/11693/16893Abstract
Hubs are special facilities that serve as switching, transshipment and sorting nodes in
many to many distribution systems. The hub location problem deals with the selection of
the locations of hub facilities and finding assignments of demand nodes to hubs
simultaneously. The p-hub maximal covering problem, that is one of the variations of
the hub location problems, aims to find locations of hubs so as to maximize the covered
demand that are within the coverage distance with a predetermined number of hubs. In
the literature of hub location, p-hub maximal covering problem is conducted in the
framework of only binary coverage; origin-destination pairs are covered if the total path
length is less than coverage distance and not covered at all if the path length exceeds the
coverage distance. Throughout this thesis, we extend the definition of coverage and
introduce “partial coverage” that changes with the distance, to the hub location
literature. In this thesis, we study the p-hub maximal covering problem for single and
multiple allocations and provide new formulations that are also valid for partial
coverage. The problems are proved to be NP-Hard. We even show that assignment
problem with a given set of hubs for the single allocation version of the problem is also
NP-Hard. Computational results for all the proposed formulations with different data
sets are presented and discussed.