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Publication Metadata only An analytical approach for analysing the impact of risks on production planning: Case of Öztiryakiler(2020) Telatar, E.; Bekeç, T.; Başaran, A.; Balıkçı, N.; Bilgin, B.; İlbay, E.; AKTİN, AYŞE TÜLİNAccurate and applicable production plans are a must for manufacturing companies. Although companies tend to prepare ideal production plans, some exogenous factors can affect their validity. These risks, which occur unexpectedly, will have a negative influence on the plan. This study aims to determine the exogenous factors affecting the success of production planning of square and rectangular food containers manufactured by Öztiryakiler, and analyse their impacts on the plans. The risk factors are evaluated using Failure Mode and Effects Analysis, and their risk priority numbers are calculated. A mixed-integer linear programming model with the objective of total cost minimisation is developed to obtain the production plan of containers. Initially, an ideal data set is used as input; hence, this model’s output displays a risk-free plan. Similarly, for each of the risk factor scenarios, mathematical models are solved with risk-related data. GAMS software and CPLEX solver is utilised in the solution of all models. Finally, for each of the selected high risk alternative, the expected total costs are calculated. This is achieved by multiplying the normalized risk priority number obtained from the Failure Mode and Effects Analysis with the corresponding optimal total cost of the risky plan. This analysis highlights the most critical risks, and comparison with the risk-free plan helps in proposing system improvements. © 2020, Springer Nature Switzerland AG.Publication Metadata only Investigation of New Facility Location Fır Elvan Gıda(2019-06) Dinçer, Tutku; Tuncer, Müge; Özgür, Müge; İnce, Buse; Bayramoğlu, Feyzanur; Altınyar, Aydan; YÜKSEKTEPE, FADİME ÜNEY; 108243Elvan Gıda, established in 1952 as a small candy shop in Istanbul, started to manufacture sweet and chocolate to meet high quality confectionery demand with affordable prices. Elvan has 7 different production facilities located in Istanbul (5), Sakarya and Eskişehir. Currently, company is dealing with a problem of gathering all facilities in a single facility to eliminate fixed operating costs of each while covering desired increased capacity. In this study, an analytical approach will be proposed to solve the facility location problem of the company. First of all, the necessary data about distribution channels of finished goods, transportability, capacity of current and planned facilities, desired optimal distance to Ambarlı harbor and planned budget will be collected. According to determined criteria’s, AHP methodology will be used for selecting 5 promising potential alternatives by considering the executive boards’ evaluations. As a next step, a mathematical model will be developed to decide the least cost location alternative by considering both inbound and outbound transportation costs. Consequently, the optimal facility location with an aggregate layout plan will be proposed to ELVAN company.Publication Metadata only Solving the Cutting Stock Problem for a Steel Industry(Springer-Verlag Singapore Pte Ltd., 2022) ÜLKÜ, İLAYDA; TEKEOĞLU, UĞUR; ÖZLER, MÜGE; ERDAL, NİDA; TOLONAY, YAĞIZThe problem of stock cutting takes an important place in the steel industry, as it is in many sectors. It is desired to ensure a minimum amount of waste in every manufacturing factory. Reaching the minimum level of waste reduces the costs of factories and companies and strengthens the possibility of making profits. In this way, it is ensured that our resources are used correctly in our developing world. In this study, the Cutting Stock Problem has been handled, in order to minimize the amount of waste within the scope of the complete the study and to solve this problem. In this study, first of all, the size of the steel to be used in line with the customer's request, the process of taking the steel plates from the stock and the molds of the parts to be cut are prepared by the production planning department, and these operations are carried out with the program used in the factory. Then the dies are sent to the workshop for cutting, where they are cut. Before creating the model, the data of the molds made for the previous cut are collected. In order to create the correct mathematical model, the data are collected by making simultaneous measurements at the cutting table. The cutting Stock Problem is used to formulate the molds prepared for cutting and the amount of waste loss is calculated. Determined parameters and constraints GAMS software is used to create a mathematical model using the GAMS MIP (Mixed Integer Programming) method and then analyze the created model. As a conclusion, we investigated 3 different scenarios. According to those experiments, the study with the proposed scenario can achieve a better production line especially about time and waste amount. Those developments can be important earnings for a real production line.Publication Metadata only A mathematical model for the delivery routing problem via drones(Pamukkale Üniversitesi, 2019) Han, Sinem; Özer, Begüm; Alioğlu, Barış; POLAT, ÖZGÜR; AKTİN, AYŞE TÜLİNLogistics sector aims to distribute merchandise to designated places on time, while focusing on the entire process that starts from storing the goods at warehouses. Transportation by land is the most common and preferred way in logistics in terms of cost and service. Studies have been going on for drone transportation with the purpose of reducing the service time and making the process automated. Advancement of this technology has led to an increase in transportation with drones. Traffic is a huge problem in land transportation causing delays in delivery time. Furthermore, nature and economy are affected because of the CO2 emission, which is a consequence of intense traffic. In this study, utilizing drones for delivery is proposed with the aim of increasing customer satisfaction and minimizing transportation cost per delivery in a green way. Istanbul's Bakirkoy district is selected as the implementation region, and daily drug delivery to pharmacies with drones is examined. In the first stage, a mathematical model that uses pharmacy coordinates as an input is developed for clustering analysis. In the second stage, one of these clusters is selected, and the location of the drone center that will serve pharmacies in the cluster is obtained by center of gravity method. Then, a vehicle routing model is proposed for finding the drone routes and calculating the total distance travelled within this cluster. Mathematical models are solved with GAMS/CPLEX solver. It is believed that this study will trigger new studies in "green delivery" literature in near future.Publication Metadata only Technician Planning in Arçelik Authorized Services via Optimization(2019-09) Çebi, Ceren; Kurtoğlu, Gizem; Öcal, Cansu; YÜKSEKTEPE, FADİME ÜNEY