Browsing by Author "Ercan, Elif"

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Citation - WoS: 13
Citation - Scopus: 16
Multi-Period Vehicle Routing & Replenishment Problem of Neighbourhood Disaster Stations for Pre-Disaster Humanitarian Relief Logistics
(ELSEVIER, 2019) Mahmut Ali Gokce; Elif Ercan; Gökçe, Mahmut Ali; Ercan, Elif
Natural disasters are uncontrollable situations that affect human life directly. Despite the researches and technological progress it is still not possible to predict when or where the natural disaster will occur beforehand. Natural disasters cause severe loss of lives and damages. In addition they cause physical financial social and environmental losses. Pre-disaster during disaster and post-disaster activities are significant in order to decrease the losses caused by natural disasters. This study is about one of the pre-disaster activities. In the pre-disaster management process a new activity is being tried in Turkey. Called Neighborhood Disaster Stations containers filled with emergency relief items such as medicines painkillers antiseptics and canned goods are located at the different predetermined locations. It is important to keep items in these stations usable at all times. Since these commodities have expiration dates they need to be replenished periodically in order to remain useable at any time. The proper time for the replenishment should be determined by considering the probability of reselling or re-using the commodities with the maximum return as much as possible. However replenishing frequently will result in large operational costs. Therefore there is a trade-off between routing costs and replenishment. We propose a novel mixed integer-programming model in order to solve this problem. The proposed model determines the replenishment policy for each commodity in the containers and generates the route of each vehicle within a given planning horizon. The objective of this study is to maximize the total profit which is the difference between expected revenue from reselling and the transportation cost for total routing costs for time periods in the planning horizon. The model determines the replenishment date of each commodity in each disaster container and provides optimal route for each vehicle within planning horizon. The proposed mixed integer programming model is solved optimally for a small instance in IBM ILOG CPLEX Optimization Studio 12.8 and validation of the model is done. (C) 2019 IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.
Citation - Scopus: 6
Optimization of Costs in Empty Container Repositioning
(Springer Science and Business Media Deutschland GmbH, 2020) Mehmet Yasin Göçen; Öykü Çağlar; Elif Ercan; Damla Kizilay; Ercan, Elif; Kizilay, Damla; Göçen, Mehmet Yasin; Çağlar, Öykü; M.N. Osman Zahid , R. Abd. Aziz , A.R. Yusoff , N. Mat Yahya , F. Abdul Aziz , M. Yazid Abu , N.M. Durakbasa , M.G. Gençyilmaz
In this study the empty container repositioning problem in a liner shipping company is considered. The research includes necessary information about the company and maritime transportation highlighting the importance of empty container storage. As the worldwide containerized trade increases the container traffic increases. Consequently the surplus containers are repositioned to locations where they are required which causes high costs. Therefore in the existing system the company deals with higher prices. In this study the storage location of the empty containers which are coming from the vessels to the ports are determined according to the different cost policies of the warehouses. Thus our problem is defined as an empty container repositioning problem. The primary objective of this study is to build an operations-research based decision-making system in order to minimize the total cost regarding changing prices of warehouses and transportation cost of containers. In the decision-making process this study will help the company to overcome the complexity about repositioning empty containers regarding the container size storage day of the containers changing inventory holding costs of the warehouses and the transportation costs of the containers from port to the corresponding warehouses. Taking into consideration all these parts of the problem this study will eventually help in reducing inventory holding and transportation costs of the empty container storage. As a solution methodology the mixed integer linear programming model is proposed and optimal solutions are obtained in a concise time. © 2022 Elsevier B.V. All rights reserved.