Person: ÜLKÜ, İLAYDA
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Dr. Öğr. Üyesi
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ÜLKÜ
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İLAYDA
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Publication Open Access Triggering Corporate Sustainable Performance in Construction Sector through Green Training: Moderating Effect of Barrier in Construction Management(Yıldız Teknik Üniversitesi Rektörlüğü, 2023) WARIS, IMRAN; ÜLKÜ, İLAYDAConstruction barrier plays a significant but negative role-play between green training and corporate sustainability performance due to limited resources. The research question in this study is to explore the relationship between green training and sustainable performance in the construction industry, while also considering the moderating role of construction barriers. This study gives extensive knowledge of green training and corporate sustainability performance. Data is obtained from 225 employees using a convenience sampling technique from the construction sector. The research employed SPSS/PROCESS and follows a cross-sectional research design. Study findings show green training is an antecedent of the sustainable performance of the construction sector. The result shows that Green training significantly and positive role-play in sustainable performance. Person-organization fit theory covers the whole phenomenon. That focuses on productivity, performance, and personal well-being. Under P-O fit theory results are showing the compatibility between a person and an organization where they are doing work. This study's results highlight the green training that transforms the em- employee’s mindset towards corporate sustainable performance. In the future, need longitudinal studies that will be more acceptable. This study provides insights to the managers, policymakers, and practitioners of sustainable environment and performance. The current study will help economies in the developing world, such as Pakistan.Publication Metadata only Optimization of Multi-token circulation with master UAV method in multi-UAV systems for location information sharing(2019) Ülkü, Eyüp Emre; ÜLKÜ, İLAYDAIn order to perform smooth and coordinated flights in multi-UAV systems, UAVs (Unmanned Aerial Vehicle) need to know each other's location information. Multi-token circulation method allows UAVs to learn each other's location information in the Flying Ad Hoc Network (FANET) quickly and this information can be updated continuously. In the multi-token circulation method, it is very important to determine how many tokens are used and how these tokens circulate in the FANET depending on the number and deployment of the UAVs. In this paper, we developed a master UAV method to determine number of tokens and circulation of these tokens.Publication Open Access Optimization of cable layout designs for large offshore wind farms(John Wiley and Sons Ltd Wiley, 2020) Alabaş Uslu, Çiğdem; ÜLKÜ, İLAYDAInstallation of a wind farm exposes several problems such as site selection, placement of wind turbines in the site, and designing of cable infrastructure within the farm. The latter problem, called cable layout design, is the determination of cable connections among turbines and one or more transmitters such that energies generated by turbines will be sent through the cable routes, and eventually gathered at the transmitter(s). This problem is especially important for offshore wind farms where the featured and expensive cables are used. The main objective of the present study is to address the cable layout design problem of offshore wind farms to reduce cable costs in the design using optimization-based approaches. The problem, firstly, is modelled as a mixed integer linear program (MIP) under a set of real-life constraints such as different cable and transmitter types and non-crossing connections between the turbines. Then, a novel mathematical model, which is a modification of the MIP model by imposing several heuristic rules, is proposed to solve the layout problem of large offshore wind farms. Experiments on a set of small- and moderate-sized test instances reveal that the heuristic model, MIP_H, reduces the computer time nearly 55% compared to that of MIP model while the average cable costs generated by the models are close to each other. MIP_H, besides its efficiency, provides more cost-effective layouts compared to MIP model for large-sized real-life examples. Additionally, a comparative study on MIP_H and existing methods in the literature shows that MIP_H is able to solve all instances of the real-life examples providing less cable costs in average.Publication Metadata only Optimization of Offshore Windfarm Cable Layouts(2018-06) Alabaş Uslu, Çiğdem; ÜLKÜ, İLAYDA; 51700; 126061As renewable energy arises to be an alternative energy source around the world, installation of the wind farms increases in the areas where the wind potential is efficient. One of the design problems in the installation of wind farms is determination of cable connections between turbines and transmitter(s) to provide the flow of generated energy from each turbine to the transmitter(s) through one or more routes. While layout of turbines should minimize wake losses to provide maximum of energy production, layout of cables should provide gathering of total energy at one or more transmitters minimizing total cost of cables. The present study takes layout of a set of turbines and a single transmitter as input data and addresses the optimization of cable layout problem to minimize of total cost of cables which can be different in types and capacities. The problem is modeled as a mixed integer linear program and optimal solutions or feasible solutions are obtained to a set of test instances using the proposed model. Experiments show that the instances can be optimized up to 20 turbines and feasible solutions are available for the larger problems.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 Holistic Approach For The Optimization of Offshore Wind Farm Layouts Considering Cable Layouts(2019-08) Alabaş Uslu, Çiğdem; ÜLKÜ, İLAYDA; 51700A wind farm, mainly, is composed of a set of turbines, one or more transmitters and a set of electrical cable connections between turbines and transmitters. Determination of turbine locations within the farm to maximize total power generation is called turbine location (TL) problem. Relative turbine positions affect the amount of overall energy because of wake effects. Determination of cable connections among turbines and transmitters to collect produced energy by turbines at transmitters is called cable layout (CL) problem. While TL problem is directly effective on the total energy production in the farm, CL problem indirectly affects the total energy due to the power losses. In the literature, TL and CL problems are solved sequentially where the layout found by solving of TL is used as an input of CL problem. To minimize wake effects in TL problem, distances between turbine pairs should be increased, however, as the distances are increased the cable cost increases in CL problem. A new mathematical model is developed to deal with simultaneously solving of TL and CL problems. A set of test instances are used to show the performance of the proposed model. The experiments show the practical use of the proposed holistic model.Publication Metadata only Monthly Logistics Planning for a Trading Company(Springer-Verlag Singapore Pte Ltd., 2022) ÜLKÜ, İLAYDA; KULLAB, HUTHAYFAH; AL MULQI, TALHA; ALMSADI, ALI; ABOUSALEH, RAEDIn this study, the transportation problem is considered in order to minimize the total traveling distance between the nodes. The nodes represent the hospitals and the warehouse. The data is obtained by Salem Trading Company (STC) that operates in various medical sectors including Urology, Gynecology, Endoscopy, Surgery, and other operations. STC has two types of vehicles; the big vehicle and the small vehicle. The big vehicle is used for the machines and it contains up to 4 machines. Whereas, the small vehicle is used for delivering the masks and gloves and its capacity is up to 200 boxes. In order to serve all the market need, they currently have a traditional logistics plan to ship products from the main warehouse to the Hospitals located in Qatar. In this study, there are two stages proposed to solve the transportation problem. In the first stage, the assignment problem is used to determine the unused capacity of each vehicle used. Then, the output of the first stage is used as an input in the second stage in order to apply the Vehicle Routing Problem (VRP). With this second stage, the optimal routes are obtained with the minimum cost. Firstly, the required data will be obtained from the company, which include the number of hospitals, the demand of each hospital, the capacity of the vehicles, the distance between hospitals and the warehouse, loading and unloading time of the vehicle, and the volume of the products. This study focus on finding the low-cost weekly logistics plan for hospitals in Qatar. Two mathematical models are developed to solve the problem with GAMS software. As a result, by using the assignment and VRP model, the unused capacity is increased from 38 to 18 and reduce the cost from 2470 TL to 1170 TL as in Qatar the cost of the fuel is not high, also on the time restriction is focused.Publication Metadata only Rüzgar Türbinlerinin Yerleşim Problemi için Yeni Bir Matematiksel Model(2018-06) ÜLKÜ, İLAYDA; 51700Enerji talebindeki hızlı artışla birlikte, yenilenebilir enerji dünya çapında alternatif bir enerji kaynağı olarak görülmektedir. Rüzgâr enerji santralleri, rüzgâr potansiyelinin en verimli olduğu bölgelere yerleştirilmektedir. Bir rüzgar türbini rüzgardan elde edilen kinetik enerjiyi mekanik enerjiye ve daha sonra elektrik enerjisine çevirir. Bu süreç, aynı zamanda, türbinin arkasında hava akımının değiştiği “gölge" adı verilen bir bölge oluşturur. Bu bölgede rüzgar hızı azalır ve hava akımı girdaba dönüşür. Gölge bölgesine yerleştirilmiş başka türbinler varsa, bu türbinlerin kullandığı rüzgar hızı azaldığı için enerji üretim miktarları da azalmaktadır. Dolayısıyla, rüzgar türbinlerinin birbirlerine göre nasıl konumlandırılacağı “rüzgar türbinlerinin yerleşim CRTYJ problemi” ortaya çıkmaktadır. Gölgelenme etkisi, rüzgâr enerji santrallerinde yıllık enerji üretimini önemli ölçüde etkilemektedir. Bu çalışmada, rüzgar türbini gölgelenme etkisini en aza indirerek enerji üretim miktarını en yüksek seviyeye çıkaracak şekilde RTY problemi ele alınmaktadır. Bu problemde, yerleştirilecek türbin sayısının önceden belirlendiği kabul edilmekte ve gölge etkilerinin hesaplanmasında Jensen modeli kullanılmaktadır. Sunulan çalışmada yeni bir doğrusal olmayan matematiksel model geliştirilmiş ve literatürde raporlanmış olan yöntemlerle bir karşılaştırma yapılmıştır. Karşılaştırma amacıyla, rüzgarın sabit olduğu ve 36 farklı yönden estiği rüzgar senaryosu ve rüzgarın farklı hızlarda ve farklı yönlerden esme olasılıklarının söz konusu olduğu rüzgar senaryosu dikkate alınmıştır.Publication Metadata only Wind farm layout optimization to maximize total power production(2018-05) Alabaş Uslu, Çiğdem; ÜLKÜ, İLAYDA; 51700; 126061With the rapid increase in energy demand, renewable energy has been considered as an alternative energy resource around the world. A new nonlinear mathematical model is developed in the presented study and a comparison is obtained with a mathematical modelling study from the literature. The results superior according to power generation under a single wind direction. Jensen’s wake decay model is used to state multiple wake effect among the turbines. The power production is maximized in terms of the minimization of wake effects. Mathematical formulations are represented and compared with the model from the literature. The generated layouts are presented and expected power among the Introduction turbines are significantly improved.Publication Restricted Forecasting of Turkey's Total Electricity Consumption in Sectoral Bases Using Machine Learning Algorithms(Institute of Electrical and Electronics Engineers Inc., 2022) HAJJAR, MHD KHAIR; ÜLKÜ, İLAYDAElectrical energy is a milestone in the economic growth of each country. This study forecasts the sectoral and total electricity consumption in Turkey until the year 2050. This study, utilize two distinct time series forecasting methods namely Multilayer Perceptron (MLP) and Sequential Minimal Optimization (SMO) as a model to generate the forecasting formulas. The sectoral and total electricity consumption for Turkey from the year 1970 to 2020 was obtained from the Turkish Statistical Institute and fed to the models to forecast the upcoming years. The two models were evaluated and compared using determination coefficient R2 and mean absolute percentage error MAPE. It is found that MLP performed better in forecasting the commercial, governmental, illumination and other sectors and SMO performed better in forecasting the industrial and household sectors alongside the total electricity consumption. © 2022 IEEE.