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Author Lespay, H.; Suchan, K.
Title A case study of consistent vehicle routing problem with time windows Type
Year 2021 Publication International Transactions In Operational Research Abbreviated Journal Int. Trans. Oper. Res.
Volume 28 Issue Pages 1135-1163
Keywords vehicle routing; multiperiod routing; distribution logistics; service consistency; customer satisfaction; heuristics
Abstract We develop a heuristic for the consistent vehicle routing problem with time windows (ConVRPTW), which is motivated by a real-world application at a food company's distribution center. Besides standard VRPTW restrictions, ConVRPTW assigns each customer just one driver to fulfill his or her orders during the whole multiperiod planning horizon. For each driver and period, a route is sought to serve all their customers with positive demand. For each customer, the number of periods between consecutive orders and the ordered quantities is highly irregular. This causes difficulties in the daily routing, negatively impacting the service level of the company. Similar problems have been studied as ConVRP, where the number of drivers is fixeda priori, and only the total travel time is minimized. Moreover, the clients present no time window constraints, but the visits should be scheduled with a small arrival time variation. In our model, the objective is to minimize the number of drivers. We impose hard time windows but do not consider time consistency in more detail. We compare solutions given by the heuristic with solutions of a mixed-integer linear programming model on a set of small artificial instances and solutions used by the food company on real-world instances. The results show the effectiveness of the heuristic. For the company, we obtain significant improvements in the routing plans, with a lower number of vehicles and a higher rate of orders delivered within the prescribed time window.
Address [Lespay, Hernan] Univ Adolfo Ibanez, Fac Ingn & Ciencias, Ave Diagonal Torres 2640, Santiago 7941169, Chile, Email: hlespay@alumnos.uai.cl;
Corporate Author Thesis
Publisher Wiley Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0969-6016 ISBN Medium
Area Expedition Conference
Notes WOS:000579246000001 Approved
Call Number UAI @ alexi.delcanto @ Serial 1232
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Author Mondschein, S.; Yankovic, N.; Matus, O.
Title Age-dependent optimal policies for hepatitis C virus treatment Type
Year 2019 Publication International Transactions In Operational Research Abbreviated Journal Int. Trans. Oper. Res.
Volume to appear Issue Pages 27 pp
Keywords dynamic programming; public health; hepatitis C virus
Abstract In recent years, highly effective treatments for hepatitis C virus (HCV) have become available. However, high prices of new treatments call for a careful policy evaluation when considering economic constraints. Although the current medical advice is to administer the new therapies to all patients, economic and capacity constraints require an efficient allocation of these scarce resources. We use stochastic dynamic programming to determine the optimal policy for prescribing the new treatment based on the age and disease progression of the patient. We show that, in a simplified version of the model, new drugs should be administered to patients at a given level of fibrosis if they are within prespecified age limits; otherwise, a conservative approach of closely monitoring the evolution of the patient should be followed. We use a cohort of Spanish patients to study the optimal policy regarding costs and health indicators. For this purpose, we compare the performance of the optimal policy against a liberal policy of treating all sick patients. In this analysis, we achieve similar results in terms of the number of transplants, HCV-related deaths, and quality of adjusted life years, with a significant reduction in overall expenditure. Furthermore, the budget required during the first year of implementation when using the proposed methodology is only 12% of that when administering the treatment to all patients at once. Finally, we propose a method to prioritize patients when there is a shortage (surplus) in the annual budget constraint and, therefore, some recommended treatments must be postponed (added).
Address [Mondschein, Susana; Matus, Omar] Univ Adolfo Ibanez, Fac Ingn, Diagonal Las Torres 2640, Santiago 755000, Chile, Email: susana.mondschein@uai.cl;
Corporate Author Thesis
Publisher Wiley Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0969-6016 ISBN Medium
Area Expedition Conference
Notes WOS:000481229600001 Approved
Call Number UAI @ eduardo.moreno @ Serial 1041
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