Thesis Defense - Burak Lefkur (MSIE)

Burak Lefkur - M.Sc. Industrial Engineering

Assoc. Prof. Dr.  Ali Ekici – Advisor

Date: 10.06.2021

Time: 13:30

Location: This meeting will be held ONLINE. Please send an e-mail to gizem.bakir@ozyegin.edu.tr in order to participate in this defense.

SINGLE MACHINE SCHEDULING WITH SEQUENCE-DEPENDENT SETUP TIMES

Thesis Committee:

Assoc. Prof. Dr. Ali Ekici, Özyeğin University

Assoc. Prof. Dr. Okan Örsan Özener, Özyeğin University

Prof. Dr. Serhan Duran, Middle East Technical University

Abstract:

In this thesis, we study a single machine scheduling problem with sequence dependent-setup times where the jobs are processed in shifts with constant length. There is a certain amount of time between each pair of consecutive shifts for periodic maintenance, the machine does not work in maintenance but this time can also be used for the setup. Our goal is to complete the jobs in a minimum amount of time. The setting considered in this thesis has applications in different industries including beverage and chemical industries. The problem can be solved with a small number of jobs by using some mathematical models in a computer environment. However, as the number of jobs increases, the difficulty of solving the problem increases exponentially. In order to overcome the problem, we proposed heuristic algorithms, and they provided us to find good solutions for the problem. The new heuristic algorithm is based on the First Fit Algorithm (FF) that is used for the solution of bin packing problems. As a beginning, First Fit Decreasing (FFD) Algorithm has been applied to the problem, and jobs were assigned to shifts. For each shift in the result of FFD algorithm, used setup times were reduced by changing the orders of jobs in the shift. The gaps occurred in some shifts with a decrease in setup time used. All shifts were combined to fill in the gaps and FF algorithm was run. This process was repeated until there is no more improvement to be achieved for a completion time of the last job. This algorithm was named as Improved First Fit Heuristic (IFFH) algorithm. Then, according to the result of IFFH algorithm, binary combinations of shifts and last shifts were concatenated. The IFFH algorithm was repeated three times for the triple combinations of shifts. The minimum completion time was accepted as a solution. This algorithm was named as Improved First Fit Heuristic-2 (IFFH-2) algorithm. Consequently, the algorithms were compared with benchmarks in the literature.

Bio: 

Burak Lefkur was born in İstanbul, Turkey on September 18, 1994. He received a Bachelor of Science degree in Industrial Engineering from Istanbul Technical University in 2017. After graduation, he started to work as Budget Control and Reporting Specialist at Vestel. He started to Master of Science program at Ozyegin University in 2018. He has been working as Purchasing Specialist at Vestel since November 2020.