Browsing by Author "Eliiyi, Ugur"

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Citation - WoS: 13
Citation - Scopus: 14
Energy-efficient single machine total weighted tardiness problem with sequence-dependent setup times
(Springer Verlag service@springer.de, 2018) M. Fatih Tasgetiren; Hande Oztop; Uǧur Eliiyi; D. T. Eliiyi; Quanke Pan; Tasgetiren, M. Fatih; Fatih Tasgetiren, M.; Oztop, Hande; Pan, Quan-Ke; Eliiyi, Ugur; Eliiyi, Deniz Tursel; P. Premaratne , P. Gupta , D. Huang , V. Bevilacqua
Most of the problems defined in the scheduling literature do not yet take into account the energy consumption of manufacturing processes as in most of the variants with tardiness objectives. This study handles scheduling of jobs with due dates and sequence-dependent setup times (SMWTSD) while minimizing total weighted tardiness and total energy consumed in machine operations. The trade-off between total energy consumption (TEC) and total weighted tardiness is examined in a single machine environment where different jobs can be operated at varying speed levels. A bi-objective mixed integer linear programming model is formulated including this speed-scaling plan. Moreover an efficient multi-objective block insertion heuristic (BIH) and a multi-objective iterated greedy (IG) algorithm are proposed for this NP-hard problem. The performances of the proposed BIH and IG algorithms are compared with each other. The preliminary computational results on a benchmark suite consisting of instances with 60 jobs reveal that the proposed BIH algorithm is very promising in terms of providing good Pareto frontier approximations for the problem. © 2018 Elsevier B.V. All rights reserved.
Intelligent Container Repositioning with Depot Pricing Policies
(Springer Science and Business Media Deutschland GmbH, 2022) Ceyhun Güven; Erdinc Oner; Uǧur Eliiyi; Eliiyi, Ugur; Guven, Ceyhun; Oner, Erdinc; C. Kahraman , S. Cevik Onar , B. Oztaysi , I.U. Sari , A.C. Tolga , S. Cebi
Empty container management has always been a crucial issue in the logistics sector. Specifically the repositioning of empty containers plays an important role in the industry of maritime shipping. Not only has an economic impact on the stakeholders affiliated with the container logistics chains but also has an effect on the society in terms of environment and sustainability as the reduction in the movement of empty containers will also reduce fuel consumption. The main objective of this paper is to minimize the total cost. This total cost includes the cost required for transportation of the empty containers to their depots and the storage cost of these containers in the assigned depots. The types of costs involved in empty container repositioning are defined via the review of the related literature and industrial practices. In this study a mixed-integer linear programming model is developed that minimizes the total cost require in the repositioning of empty containers. The proposed model determines the storage depot of each empty container considering the depot pricing policies and distances between the port terminals and container depots. Computational results indicate that the proposed model can identify the best alternatives for empty container storage with minimum total cost. © 2022 Elsevier B.V. All rights reserved.