Master's Theses

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Browsing by Author "Akça, Berna"

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    Scheduling and routing of chronic dialysis patients in the aftermath of a disaster
    Akça, Berna; Koyuncu, Burcu Balçık; Koyuncu, Burcu Balçık; Yanıkoğlu, İhsan; Erçetin, E. D. G.; Department of Industrial Engineering; Akça, Berna
    Disasters have devastating effects on patients with chronic diseases who need regular treatments to preserve their health. In this thesis, we focus on developing effective, fast and joint solution methodologies to support the scheduling and routing decisions of chronic dialysis patients assigned to a dialysis center after a disaster. The problem involves determining whether a patient is served or transferred out of the dialysis center. The days, sessions and treatment types of patients for their visits must be assessed over the planning horizon. The vehicle routes must be constructed for each session. We formulate a multi-objective mathematical model in which the primary objective is to minimize the number of patients transferred. With their hierarchical order, the secondary objectives are minimizing the sum of the number of vehicles required each day, the number of short and normal treatments, and the total travel time. The secondary objectives increase the effectiveness of the solutions. The short treatment type is considered to decrease the number of patients transferred. Besides, visiting frequency of patients differs according to the treatment types provided. To solve this problem, we propose a constructive heuristic and two matheuristics. Within the heuristics, we apply various strategies to improve the solutions. A rapid approach for the matheuristics is proposed to obtain solutions in a shorter time. To evaluate the performance of heuristics, we provide several metrics and present insights on different problem characteristics. We perform a numerical study based on actual data of a dialysis center in Turkey. In the results, even if the same value of the primary objective is achieved under both matheuristics, in most instances, Matheuristic MO results in the best solutions. Our heuristics lead to effective solutions that can be applied in a post-disaster setting.