Scopus İndeksli Yayınlar Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/395

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  • Conference Object
    Minimising the Cycle Time with Assembly Line Balancing and Worker Assignment: A Case Study in a Medical Device Manufacturer Company
    (ISRES Publishing, 2025-10-27) Kayser, A.; Sipahi, G.; Sevimli, O.; Toplu, N.; Turan, S.; Satic, U.
    In this research, we considered the mixed-model assembly line balancing and worker assignment problems of a medical device manufacturer in Türkiye. We combined these problems into a single integer programming model where multiple types of products can be assembled simultaneously on a single assembly line, and workers are assigned to workstations based on their abilities while ensuring the balance and efficiency of the assembly line. Our proposed approach seeks to minimise the cycle time and ability-based assignment costs on the assembly line. We used the Gurobi solver to find the optimal solution for the proposed problem. Our approach provides higher efficiency and results in a 76% increase in productivity without requiring additional work hours or workers. © 2025 Published by ISRES Publishing.
  • Conference Object
    Scheduling in Flexible Flow Shop Environments with Re-Entrant Jobs and Heterogeneous Workers
    (ISRES Publishing, 2025-10-27) Bekli, S.; Kayisoglu, B.
    In many industries, manufacturing is organized as a flexible flow shop (FFS), which has gotten the researchers' attention. The scheduling studies, particularly those on FFS scheduling, are concerned with homogeneous workers with the same skill set or heterogeneous workers who can only perform one specific type of operation on the production lines. Moreover, jobs are mainly assumed to go through an operation once. Yet, in real-life production, workers might have different skill sets with varying processing times. Furthermore, certain jobs may require revisiting the same machine multiple times, i.e., re-entrant jobs. We study an FFS environment with re-entrant jobs, considering worker flexibility. We propose a mixed integer linear programming model to find the optimal sequences of jobs to be processed by the multiskilled workers assigned to the production system, ensuring each re-entrant job waits for a predefined time window before reprocessing on the same operation. The objective of the model is to minimize makespan. We tested the proposed model on a dataset taken from a real production system of a PVC windows and doors production facility. © 2025 Published by ISRES Publishing.
  • Conference Object
    Citation - Scopus: 2
    Parallel Machine Scheduling With Re-Entrant Jobs With Consideration of Set Up Times
    (ISRES Publishing, 2024-12-30) Kayisoglu, Betul; Bekli, Seyma; Sahin, Ayse Sena; Akyurek, Gamze Gul; Aydinli, Ruveyda; Copur, Sevda Nur; Ekinci, Tugba
    We study the identical parallel machine problem with re-entrant jobs. Re-entrant jobs require to pass through the processing line multiple times. In many real-life manufacturing systems with parallel machine environments, one of the scheduling problems that needs to be addressed is the order of jobs on each machine with re-entrant jobs. In addition, manufacturing systems may require periodic maintenance, systematic manufacturing equipment cleaning, or predetermined upper limits on the overtime. Therefore, machine availability may vary during the scheduling horizon. We propose an integer programming model to find the optimal sequence of the re-entrant jobs at parallel machines with consideration of machine availability. The model aims to reduce setup times and maximize capacity utilization by scheduling tasks with similar set up requirements consecutively. We tested the proposed model at a panel line manufacturing company located in Turkey. The order of the panels is scheduled optimally by the proposed model for 3 different instances on the identical parallel machines for the coating process. We also provided relevant information on the user interface we developed to make the proposed scheduling model usable to by the company. The proposed model and interphase offer a systematic approach to panel line planning and can also be implemented in other industries. © 2025 Elsevier B.V., All rights reserved.
  • Conference Object
    Citation - Scopus: 1
    Incorporating Worker Heterogeneity in Flexible Flow Shop Environment
    (ISRES Publishing, 2025-08-15) Ozpacaci, Kubra; Bekli, Seyma; Kayisoglu, Betul
    We study the flexible flow shop scheduling problem with the heterogeneous worker assignment. In many real-life manufacturing systems with flow shop environments, one of the fundamental scheduling challenges that needs to be addressed is job sequences across multiple workers. In addition, the manufacturing system may require workers to have different skills at various stages during their assignment. Therefore, worker availability at each stage may vary during the scheduling horizon. Unlike traditional flexible flow shop scheduling problem, where homogeneous workers are assumed, we consider workers with different skill levels, capabilities, and capacities. We present a mixed integer linear programming model to find the optimal sequence of job assignments, guaranteeing that jobs follow their predefined operation sequence while assigning workers with various skill sets in a flexible flow shop environment. The proposed model is tested at a battery manufacturing company. By analyzing the solution, we confirm its capability to represent the problem accurately. The proposed model offers a systematic scheduling approach for a flexible flow shop environment with a heterogeneous workforce and can be implemented in other industries. © 2025 Elsevier B.V., All rights reserved.