Browsing by Author "Mullaoğlu, Gizem"

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Industry 4.0 challenges to IE paradigms: A pilot study in materials handling
(International University of Sarajevo, 2020) Gizem Mullaoğlu; Sencer Yeralan; Yeralan, Sencer; Mullaoğlu, Gizem
Industrial engineering practices are expected to be affected by and most likely adapt to the new paradigms of Industry 4.0. Early indications in practice as well as extrapolations from the current technology trends point toward a few fundamental features. Among these are further integration leaner and hence more agile practices and the use of real-time data. The final objective is to reduce complexity while striving for real-time supply- and production-chain optimization. We argue that the optimization of highly integrated production systems cannot be sought by simply aggregating the known operations management tools of industrial engineering. Specifically we present evidence gleaned from a recent industrial project that indicates how as the systems become more integrated the concept of operations optimization needs to be revisited. Our work has two distinct contributions to the literature. We develop and present a state-of-the-art optimization model for a joint materials handling inventory and scheduling model. The model incorporates aspects of the knapsack bin packing vehicle routing and inventory control formulations. Further we show that simply collecting existing industrial engineering models into larger aggregations albeit in line with the current best practices of our profession will not necessarily suffice to completely fulfill the ambitions of Industry 4.0. © 2021 Elsevier B.V. All rights reserved.
Citation - Scopus: 1
Optimization of review periods and (S s) levels of floor stock items in a paint production environment
(IEOM Society, 2020) Banu Yetkin Yetkin Ekren; Gizem Mullaoğlu; Mullaoğlu, Gizem; Ekren, Banu Yetkin
In this paper a mixed integer linear programming model is proposed in order to optimize review periods and (s S) inventory levels of floor stock items (FSIs) in a paint production facility to decrease the number pauses in the production process. In the model power-of-two policy for periodic review scenario is considered. The optimum review periods are determined for multi-item types satisfying pre-defined cycle service level (CSL) under a capacity constraint. It is significant to determine the optimum review periods and safety stock levels of FSIs to be hold in the floor stock storage areas (FSSAs) so that the number of stops will be minimized in the production process. We model the problem as multi-item single-echelon inventory system using periodic review (s S) policy. In the facility raw materials are hold in nine inside inventory locations which are supplied from the main warehouse whose capacity is infinite. The objective function is considered as minimization of total number of reviews completed in a year i.e. the total number of transportations completed from the main warehouse. The results indicate that there is a positive correlation between the review periods and the difference between the S and s values. © 2020 Elsevier B.V. All rights reserved.
Yanal aktarma politikalarının tedarik zinciri ağları için çok amaçlı en iyileme ve benzetim modellerine etkisi
(2020) Bayram, Serkan; Mullaoğlu, Gizem
Supply chain systems play a crucial role to meet customer demands on time, especially in competitive markets. Nowadays, these systems have to consider the environment as much as economical perspectives because of the increase in carbon emission awareness and possible future regulations. Therefore, in this thesis, we developed a multi-objective mixed-integer programming and simulation models while allowing lateral transshipment distribution strategy which provides product transportation within the echelons. Also, electric vehicles are considered in these models to give more opportunities to reduce carbon emissions. As a result of these models' computational studies, it has been observed that lateral transshipment could increase the efficiency of the supply chain. However, it has been noticed that when carbon emission is more superior to the total cost, less lateral transshipment occurs. Therefore, we can conclude that even though lateral transshipment provides efficiency in the total cost, it is less favorable when carbon emission is more important. Moreover, it has been observed that electric vehicles have a positive effect on total carbon emission and total cost as expected. Hence, electric vehicles can play a crucial role in the supply chain system if they can be integrated more in line with lateral transshipment policies.