Browsing by Author "Cetinkaya, F. C."

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Citation - WoS: 2
Citation - Scopus: 3
Single-Machine Scheduling of Indivisible Multi-Operatıon Jobs
(Southern African inst industrial Engineering, 2019) Çetinkaya, Ferda Can; Cetinkaya, F. C.; Catmakas, H. A.; Görür, Abdül Kadir; Gorur, A. K.; 50129; 57532; 107251; Endüstri Mühendisliği; Bilgisayar Mühendisliği
This paper considers a single-machine scheduling problem of multi-operation jobs where each job consists of several operations processed contiguously, rather than being intermingled with the operations of different jobs. That is, the jobs are indivisible. A sequence-independent setup is required if the machine switches from one operation to another. However, no setup is necessary before the first operation of a job if this first operation is the same as the last operation of the immediately previous job. A job is complete when all of its operations have been processed. We investigate the problem for two cases. Makespan, which is the time needed to complete all jobs, is minimised in the first case; whereas the total completion time, which is the sum of the job completion times, is minimised in the second case. We show that the makespan problem is solvable in polynomial time. For the problem of minimising total completion time, we develop a mixed integer linear programming (MILP) model, which is capable of solving small and medium-sized problem instances optimally, and obtain a very small gap between the solution found and the best possible solution for the unsolved large-sized problem instances.
Citation - WoS: 4
Citation - Scopus: 4
Unrelated Parallel Machine Scheduling Under Machine Availability and Eligibility Constraints To Minimize the Makespan of Non-Resumable Jobs
(Univ Novi Sad, Fac Technical Sciences, 2024) Kurt, A.; Cetinkaya, F. C.
This study considers the scheduling problem of multiple independent and non-resumable jobs on unrelated parallel machines subject to machine availability and eligibility constraints. For each machine, there is a maximum continuous working time due to an unavailable period required for maintenance or tool changeover so that multiple unavailable periods on each machine may occur. The start time of an unavailable period on each machine is flexible and depends on the sum of the processing times of all jobs completed before this unavailability period. The objective is to minimize the makespan, which is the time to complete the processing of all non-resumable jobs. We develop a mixed integer linear programming (MILP) model to solve the problem optimally and a heuristic algorithm to solve the problem instances for which the MILP model cannot achieve an optimal solution in a reasonable allowed solution time. Computational experiments are done to evaluate our solution approaches' performance in terms of quality and time. The results show that using a mixed integer linear programming model is not a practical alternative, especially for large -sized problem instances. However, the proposed heuristic algorithm finds near -optimal solutions in a very short time.