Browsing by Author "Azizoglu, Meral"

Now showing 1 - 4 of 4

Citation - WoS: 5
Citation - Scopus: 5
A blood distribution problem with new transportation options - an application for the Turkish Red Crescent
(inderscience Enterprises Ltd, 2019) Kurt, Atıl; Kurt, Atil; Cetinkaya, Ferda Can; Çetinkaya, Ferda Can; Azizoglu, Meral; 50129; Endüstri Mühendisliği
This paper considers the blood distribution problem in the Central Anatolian Regional Blood Centre of the Turkish Red Crescent (TRC) and proposes several demand satisfaction options considering the irradiation centres, urgent demands, and product availability. Our aim is to maximise the total weighted blood demand satisfaction. To address the problem, we develop a mixed integer linear programming model and propose a hybrid genetic algorithm (HGA). The results of our experiments have revealed that the mathematical model cannot handle even small sized problem instances in reasonable times; however, the hybrid genetic algorithm is capable of handling complex daily operations of the Turkish Red Crescent.
Citation - WoS: 0
Citation - Scopus: 0
An integrated inventory and distribution planning problem for the blood products: An application for the Turkish Red Crescent
(Growing Science, 2023) Kurt, Atıl; Kurt, Atil; Azizoglu, Meral; Çetinkaya, Ferda Can; Cetinkaya, Ferda Can; 50129; Endüstri Mühendisliği
This study considers an integrated inventory planning and distribution problem based on an applied case at the Turkish Red Crescent's Central Anatolian Regional Blood Center. We define two echelons, the first echelon being the regional blood center and the second echelon being the districts. The blood products are perishable so that the outdated products are disposed of at the end of their lives. We aim to minimize the cost of inventory keeping at both echelons, the shortage, and disposal amounts at the second echelon. We consider two distribution strategies: all deliveries are realized by the regional blood center (current implementation), and the deliveries are directly from the regional blood center or the other districts. We develop a mixed -integer linear programming model for each strategy. Our experimental results show that the decentralized strategy brings significant cost reductions over the centralized strategy. The mathematical model for the centralized distribution strategy can handle large-sized instances. On the other hand, the model for the decentralized distribution strategy is more complex and could not handle large-sized instances in our pre-specified termination limit of two hours. For large -sized instances of the decentralized distribution strategy, we design a decomposition-based heuristic algorithm that benefits from the optimal solutions of the original model and finds near -optimal solutions very quickly. (c) 2023 by the authors; licensee Growing Science, Canada.
Citation - WoS: 5
Citation - Scopus: 7
LP relaxation-based solution algorithms for the multi-mode project scheduling with a non-renewable resource
(inderscience Enterprises Ltd, 2015) Azizoglu, Meral; Çetinkaya, Ferda Can; Cetinkaya, Ferda Can; Pamir, Selin Kirbiyik; 5546; 50129; Endüstri Mühendisliği
In this study, we consider a multi-mode resource allocation problem with a single non-renewable resource. We assume the resource is released at defined time points and at defined quantities. We also assume that the activity costs are charged once they are completed. Our aim is to minimise the project completion time. We formulate the problem as a pure integer programming model and show that it is strongly NP-hard. We find lower bounds by pure and mixed integer linear programming relaxations of the model and develop three heuristic procedures based on those relaxations. The results of our computational study have revealed the satisfactory performances of our lower bounds and heuristic procedures.
Citation - WoS: 6
Citation - Scopus: 6
Solution approaches to the blood distribution problem of the Turkish Red Crescent
(inderscience Enterprises Ltd, 2018) Kurt, Atıl; Kurt, Atil; Azizoglu, Meral; Çetinkaya, Ferda Can; Cetinkaya, Ferda Can; 21650; 5546; 50129; Endüstri Mühendisliği
This paper considers the blood distribution problem that includes irradiation centres, urgent demands, and product availability in Turkey, Central Anatolian Regional Blood Center of the Turkish Red Crescent. To address the problem, we develop a mixed integer linear program with two objectives: maximising the demand satisfaction and minimising total time travelled by the vehicles. We propose two decomposition-based heuristic solution approaches. The results of our experiments have revealed that the model cannot solve even small sized instances in reasonable times; however, the heuristic solution approaches are appropriate for solving complex real life problems.