Browsing by Subject "Covering"

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    ItemOpen Access
    Clean water network design for refugee camps
    (Springer, 2021-03) Karsu, Özlem; Yetiş Kara, Bahar; Akkaya, Elif; Ozel, Aysu
    Motivated by the recent rise in need for refugee camps, we address one of the key infrastructural problems in the establishment process: The clean water network design problem. We formulate the problem as a biobjective integer programming problem and determine the locations of the water source, water distribution units and the overall network design (pipelines), considering the objectives of minimizing cost (total network length) and maximizing accessibility (total walking distance) simultaneously. We solve the resulting model using exact and heuristic approaches that find the set (or a subset) of Pareto solutions and a set of approximate Pareto solutions, respectively. We demonstrate the applicability of our approach on a real-life problem in Gaziantep refugee camp and provide a detailed comparison of the solution approaches. The novel biobjective approach we propose will help the decision makers to make more informed design decisions in refugee camps, considering the trade-off between the two key criteria of cost and accessibility.
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    The hub covering problem over incomplete hub networks
    (2006) Kalaycılar, Murat
    The rising trend in the transportation and telecommunication systems increases the importance of hub location studies in recent years. Hubs are special types of facilities in many-to-many distribution systems where flows are consolidated and disseminated. Analogous to location models, p-hub median, p-hub center and hub covering problems have been studied in the literature. In this thesis, we focus on a special type of hub covering problem which we call as “Hub Covering Problem over Incomplete Hub Networks”. Most of the studies in the hub location literature assume that the hub nodes are fully interconnected. We observe that, especially in cargo delivery systems, hub network is not complete. Thus, in this study we relax this fundamental assumption and propose integer programming models for single and multi allocation cases of the hub covering problem. We also propose three heuristics for both single and multi allocation cases of the problem. During the computational performance of proposed models and heuristics, CAB data was used. Results and comparisons of these heuristics will also be discussed.