Sürdürülebilir Kalkınma Amaçları
Yazarlar
- Kahraman, Gökhan(4)
- Işık, Erdem(3)
- Akkurt, Nevzat(1)
- Aksöz, Ahmet(1)
- Ağdaş, Mehmet Tevfik(1)
- Bakır Gür, Eda(1)
- Canpolat, Erdal(1)
- Hadi Attia, Mohammed El(1)
- Hudaverdi, Burcu(1)
- Hussein, Ahmed Kadhim(1)
- Kahraman, Gokhan(1)
- Karakaya Cirit, Didem(1)
- Korkmaz, Meral(1)
- Oyucu, Saadin(1)
- Polat, Hüseyin(1)
- Polat, Onur(1)
- Radhakrishnan, Ganesh(1)
- Susam, Selim Orhun(1)
- Taşgın, Yahya(1)
- Türkoğlu, Muammer(1)
- Uçar, Aynur(1)
- Vaithilingam, Sivakumar(1)
- Younis, Obai(1)
Yayınlar
- MakaleAçık Erişim2026Scopus SJRQ1Numerical analysis of PCM integrated in solar dryers for thermal efficiency
Bakır Gür, Eda; Işık, Erdem; Uçar, Aynur
Solar dryers using phase change materials buffer heat, yet the combined influence of airflow regime and PCM placement on melting remains underexplored. A controlled like-for-like study fixed geometry and PCM properties while varying placement and operating conditions. A 3D transient CFD model simulated a forced-convection dryer with RT28HC over Re = 3000–9000 and inlet temperatures Ti = 50–60 °C. Raising either Re or Ti shortened melt time, and three-wall coverage melted faster and more uniformly than a rear-wall-only layout. For three walls, melt time dropped from 13 h (50 °C, Re = 3000) to 7 h (60 °C, Re = 9000) (−46 %) for the rear wall it fell from 19 h to 11 h (−42 %). A 10 °C increase in Ti reduced overall melt time by 4 h across Re. Practically, three wall PCM with Re ≥ 6000 at Ti = 60 °C achieved reliably 7–9 h melting, enabling late afternoon heat release without auxiliary heating.
AtıfScopus17WoS16OpenAlex12
İncele - MakaleAçık Erişim2024Scopus SJRQ1Ensemble Learning Framework for DDoS Detection in SDN-Based SCADA Systems
Oyucu, Saadin; Polat, Onur; Türkoğlu, Muammer; Polat, Hüseyin; Aksöz, Ahmet; Ağdaş, Mehmet Tevfik
Supervisory Control and Data Acquisition (SCADA) systems play a crucial role in overseeing and controlling renewable energy sources like solar, wind, hydro, and geothermal resources. Nevertheless, with the expansion of conventional SCADA network infrastructures, there arise significant challenges in managing and scaling due to increased size, complexity, and device diversity. Using Software Defined Networking (SDN) technology in traditional SCADA network infrastructure offers management, scaling and flexibility benefits. However, as the integration of SDN-based SCADA systems with modern technologies such as the Internet of Things, cloud computing, and big data analytics increases, cybersecurity becomes a major concern for these systems. Therefore, cyber-physical energy systems (CPES) should be considered together with all energy systems. One of the most dangerous types of cyber-attacks against SDN-based SCADA systems is Distributed Denial of Service (DDoS) attacks. DDoS attacks disrupt the management of energy resources, causing service interruptions and increasing operational costs. Therefore, the first step to protect against DDoS attacks in SDN-based SCADA systems is to develop an effective intrusion detection system. This paper proposes a Decision Tree-based Ensemble Learning technique to detect DDoS attacks in SDN-based SCADA systems by accurately distinguishing between normal and DDoS attack traffic. For training and testing the ensemble learning models, normal and DDoS attack traffic data are obtained over a specific simulated experimental network topology. Techniques based on feature selection and hyperparameter tuning are used to optimize the performance of the decision tree ensemble models. Experimental results show that feature selection, combination of different decision tree ensemble models, and hyperparameter tuning can lead to a more accurate machine learning model with better performance detecting DDoS attacks against SDN-based SCADA systems.
AtıfScopus36OpenAlex27
İncele - MakaleYalnız künye2024Scopus SJRQ2Stress–strength reliability for electricity systems based on the Bernstein copula approximation
Susam, Selim Orhun; Hudaverdi, Burcu
Electricity is a critical resource for modern society, and its availability is essential for various aspects of daily life, from powering homes to supporting industrial processes and infrastructure. Ensuring a reliable supply of electricity is vital for economic stability and the well-being of a population. As the world moves toward more sustainable and renewable energy sources, understanding the reliability of these sources compared to traditional fossil fuels is crucial. In this study, we develop a methodology that enables the measurement of stress–strength reliability when electricity consumption is considered as the strength variable, positioned between electricity generation from renewable energy sources and fossil fuels as stress variables. We achieve this using the copula-based reliability with Bernstein copula approximation. The methodology is applied to the U.S. monthly electricity data. The result shows that the current rates of electricity output from fossil fuels and renewables will not be sufficient to meet the demand for electricity.
AtıfScopus2WoS3OpenAlex3İncele - MakaleYalnız künye2024Scopus SJRQ1Modeling of Optimal Power Generation in Small Hydropower Plants
Kahraman, Gokhan
Small hydropower plants (SHPs) have gained international attention as a reliable and versatile renewable energy source. Unfortunately, this energy source is not used efficiently. This is because these systems utilize headwaters with lower water capacity called forebays instead of large water reservoirs like dams. Since this hinders the control of electricity generation, the headwater is either wasted before it can be converted into electricity or it is exhausted very quickly and electricity generation stops after a short time. The aim of this study is to prevent the loss of electricity generation through the efficient use of SHP headwater. For this purpose, a mathematical model was created based on two SHPs operating in tandem. The mathematical model obtained was analyzed, and forebay water level simulation graphs for electricity generation at water flowrates of 2000, 4000, 6000, and 8000 kg/h were obtained. With the help of the obtained graphs, critical wicket gate openings for maximum electricity generation at flowrates of 2000, 4000, 6000, and 8000 kg/h were calculated. The results of this study are applicable to all SHPs. These results are also promising in terms of optimizing the use of a renewable energy source.
AtıfScopus7WoS6OpenAlex6İncele - MakaleYalnız künye2024Scopus SJRQ2Dynamic Analysis and Metallographic Examination of Linings with Different Composite Contents used in the Brakes of a Hydraulic Turbine
Işık, Erdem; Kahraman, Gökhan
The main aim of this study was to find ways to increase the performance and life of generator brake linings, which can lead to cost reduction and adequate downtime periods for hydroelectric power plants. First, the dynamic analysis of the linings used in hydraulic turbines was realized and their reactions were examined under different operating conditions. Second, two types of brake linings with different composite components produced in the market were examined metallographically and tested to determine both the stopping performance and durability time of the turbine-generator unit for a sufficient period of time in the vertical 150-megawatt Francis turbine with approximately 500 tons of rotary weight. As a result of these experiments, the lining with the boron component led to much better results than the other brake linings. It has been determined that the boron-containing lining makes 100 stops more than the other lining and stops 20 s earlier in one stop. Therefore, the use of a composite lining with boron content in the braking systems of hydroelectric power plants significantly reduces maintenance incidents and operation costs as it prolongs brake replacement periods in these plants. Graphical Abstract: (Figure presented.)
AtıfScopus1WoS1OpenAlex1İncele - MakaleAçık Erişim2023Theoretical and Practical Investigation of Stability Performance for Power Regulation in Hydroelectric Power Plants
Kahraman, Gökhan; Işık, Erdem
Hydroelectric power plants are the insurance of the interconnected system in order to provide fast energy to the system compared to other fossil fueled power plants. Hydroelectric power plants control the balance between the energy it supplies to the interconnected system and the pressurized water it uses with a system based on the fully automatic control principle. The quality of the energy supplied to the interconnected system depends entirely on this automatic control mechanism. In this study, mathematical models of the mechanisms that affect the automatic control system during the generation of energy in hydroelectric power plants are formed. Transfer functions of the obtained mathematical models are calculated by laplace transform. With the calculated transfer functions, the responses of the units of a hydroelectric power plant to the change of the amount of energy produced under different operating conditions are determined. The obtained data are compared with the actual conditions in a 1330 MW hydroelectric power plant with 8 Francis turbines. It is seen that the mathematical model and the turbine responses in real conditions are similar. In the calculations made at 115, 125, 135, 145 m. net head, the best stability conditions were obtained at 135 m. In addition, as a result of the calculations obtained under different operating conditions, ideal operating conditions are determined to minimize the fluctuations in energy production.
AtıfScopus2OpenAlex2
İncele - MakaleYalnız künye2023Scopus SJRQ1Energy, exergy and cost analysis of different hemispherical solar distillers: A comparative study
Hadi Attia, Mohammed El; Hussein, Ahmed Kadhim; Radhakrishnan, Ganesh; Vaithilingam, Sivakumar; Younis, Obai; Akkurt, Nevzat
The experimental study of the results of reflective aluminum foils, metal sheets, and phosphate granules on the productivity and efficiency of hemispherical solar stills was given throughout this work under the solar conditions of the city of El-Oued (Algeria). Solar stills were designed, manufactured, and tested in August 2020. A standard hemispherical solar still was made of wood and coated with black silicon. It was considered a traditional solar still. Although it was compared to traditional solar stills, it was improved by covering its side walls with reflective aluminum foil, zinc metal sheets, and copper sheets. It had been found that the productivity of the modified still was 8.67%, 29.08%, and 42.35%, respectively, on top of that of the traditional solar still. This could be due to the activity of the foils and metals, which reflect more radiation and store energy, increasing the temperature of the salt water in the basin. In the second experiment, three modified solar stills in line with aluminum foil and phosphate granules (30 g/L), zinc metal sheet and phosphate granules, and copper metal sheet and phosphate granules were collectively used. It had been found that the productivity of the modified solar still with aluminum foil and phosphate granules (the improvement rate is 30.61%) was on the far side of that with zinc metal sheets and phosphate granules (the improvement rate is 49.961%) and copper metal sheets and phosphate granules (the improvement rate is 62.24%).
AtıfScopus37OpenAlex34İncele - MakaleYalnız künye2021TREND ANALYSIS OF THE EFFECT OF RAIN ON SOLAR ENERGY PRODUCTION IN A SUSTAINABLE FUTURE
Korkmaz, Meral
The greatest need of the modern world is energy. From production to consumption, energy has become essential in all areas. As fossil-derived energy production systems cause global warming and climate change, interest in renewable energy sources is increasing. Despite the pandemic, solar production has shown promising growth throughout the world. Turkey has been encouraging investments in renewable energy sources, especially solar energy, for the last 10 years. Feasibility studies before the installation of solar power plants are crucial for investors. As a result of feasibility studies, the cost of the investment and the depreciation period can be calculated. In this study, feasibility studies of the 474 kWp power plant in Samsun province were carried out with PVsyst program. Significant differences were found between the software results and the actual results of the solar plant built in Samsun province. Production losses between actual data and numerical data are thought to be related to meteorological data. There are numerous studies in the literature about PV software. However. current studies have not examined the effect of meteorological data of the region on the difference in production between PV software results and solar power plant production values. In this study, the Sen method was used to determine the precipitation trend by taking meteorological data from Samsun province. With this method, rainfall in Samsun province was seen to be on an upward trajectory. For this reason, in regions where there is a lot of precipitation; feasibility studies of solar power plants are falling by approximately 9 percent.
- MakaleYalnız künye2021Scopus SJRQ1Crack failure in hydrodynamically lubricated bearings: A case study hydraulic turbine
Taşgın, Yahya; Kahraman, Gökhan
This study investigates the trunnion crack of a 50 MW hydraulic turbine in the generator guide bearing. The crack area has been examined metallographically and the fixing method for the the trunnion crack has been explained. Result of the study shows that the reason for the formation of the bearing trunnion crack can be the thermal stresses that occur during the mounting of the bearing trunnion to the turbine shaft and the material fatigue that occurs during the operation of the hydraulic turbine.
AtıfScopus9WoS7OpenAlex9İncele - MakaleYalnız künye2020Scopus SJRQ3Investigation of the Effect of Operating Conditions Change on Water Hammer in Hydroelectric Power Plants
Kahraman, Gökhan
Renewable energy sources do not harm the environment, and they contribute greatly to national economies. Hydraulic energy is the leading renewable energy source. Hydraulic energy is used more widely than other renewable energy sources around the world. This situation of hydraulic energy makes it important to solve the faults in hydraulic turbine-generator units. In this study, water hammer impacts have been investigated. This issue is important and can be dangerous in hydroelectric power plants. As a result of the research, the optimum sudden shutdown time of the adjusting wings in the snail is determined by considering the different operating conditions of a hydroelectric power plant. When the turbine-generator units are operated according to the specified instantaneous shutdown time, they will be protected against the impact of the water hammer pressure and the turbine shaft overspeed. Thus, they will be operated with less risk.
AtıfScopus9WoS8OpenAlex8İncele - MakaleAçık Erişim2019Scopus SJRQ1A study on the technological pedagogical contextual knowledge of science teacher candidates across different years of study
Karakaya Cirit, Didem; Canpolat, Erdal
This case study survey investigates the Technological Pedagogical Contextual Knowledge (TPCK) of Science Teacher Candidates (STC) across different years of study in the Topic of Renewable Energy (TRE). In line with the transformative model, the study treats TRE-TPCK as a new knowledge domain emerging from the interaction between content, technology, pedagogy and contextual knowledge. Participants were 36 Science Education students who were in their 1st, 2nd, 3rd and 4th years of study during the 2014–2015 academic year. Teacher candidates’ TPCK was identified through semi-structured interviews based on (1) Vignettes, (2) Anecdotes from a teacher named Zeynep and the (3) Content Presentation Technique (CPT). The data were analyzed by using the content analysis technique. The findings showed that the TRE-TPCK of teacher candidates across different years of study was at a similar and less-than-ideal level. STCs in different years of study mostly disregarded the macro and meso contexts when teaching the topic of renewable energy and were partially competent in the sub-meso, micro and sub-micro contexts. They particularly lacked technology-integrated evaluation knowledge when teaching TRE.
AtıfScopus8WoS8OpenAlex10İncele