GCRIS Repository Collection:https://hdl.handle.net/20.500.13091/22024-03-29T11:48:46Z2024-03-29T11:48:46ZModified Coot bird optimization algorithm for solving community detection problem in social networksAslan, MuratKoç, İsmailhttps://hdl.handle.net/20.500.13091/52172024-03-16T09:49:30Z2024-01-01T00:00:00ZTitle: Modified Coot bird optimization algorithm for solving community detection problem in social networks
Authors: Aslan, Murat; Koç, İsmail
Abstract: Community detection (CD) is a powerful way to extract meaningful information from networks such as political election networks, biological networks, social networks, technological networks. This study proposes a modified discrete version of Coot bird natural life model (COOT) optimization algorithm to solve CD problem in the networks. The basic COOT method is based on the different collective behaviors of the birds of the coot family. These collective actions of coots are regular and irregular movements on the water surface. The position update rule of the basic COOT method does not provide a balance between exploitation and exploration ability for the problem addressed in this study. Therefore, a new update mechanism is integrated into the basic COOT method to extend the local and global search tendencies of the basic COOT method. In the proposed COOT method (for short MCOOT), in order to create a new position for the current coot individual, first the original update mechanism of COOT method is carried out; then, the proposed update mechanism is executed. Three important modifications have been made in the new update mechanism: (1) Some dimensions of the current coot individual are randomly selected in the range of 1 to the dimension size of the problem; (2) the selected dimensions of the coot individual are updated according to the proposed update rule; (3) a genetic mutation operator is executed on the current coot position according to a mutation probability to improve the exploration ability. Furthermore, in the proposed MCOOT method, the continuous values of the current coot positions are converted to discrete values, because the CD problem is a discrete problem. Based on these modifications, in order to analyze and validate the effectiveness of the proposed MCOOT, it is applied on ten different small-sized or large-sized network problems. Finally, the experimental results of MCOOT method are compared with those of some state-of-the-art optimization methods in terms of solution quality and time evaluation. According to the experiments of our study, the proposed algorithm is obtained the best results for all community detection problems used in this study when compared with 22 other algorithms. As a result, the proposed method achieves superior or comparable performance in terms of solution quality and robustness according to the general results. Therefore, the proposed method can be much more competitive, especially for discrete problems.2024-01-01T00:00:00ZInvestigation of the importance of criteria in potential wind farm sites via machine learning algorithmsSarı, FatihYalçın, Mustafahttps://hdl.handle.net/20.500.13091/52132024-03-16T09:49:30Z2024-01-01T00:00:00ZTitle: Investigation of the importance of criteria in potential wind farm sites via machine learning algorithms
Authors: Sarı, Fatih; Yalçın, Mustafa
Abstract: Wind energy has received greater attention than other energy resources due to its superior economics, low greenhouse gas emissions, and limitless wind resources. As a result, wind energy capacity has significantly increased, and the selection of the best locations for wind farms is an issue that has received extensive research. A significant step toward environmentally responsible land use planning is the site suitability assessment for the placement of wind farms. This study was conducted to determine the best locations for wind farms and to pri- oritize different locations and alternatives in the West of Turkey by using Maximum Entropy (MaxEnt) and Logistic Regression (LR) Methods based on Geographic Information Systems (GIS). Eight criteria were selected for creating the suitability map: air density, power density, wind speed, capacity factor, elevation, slope, aspect, and land use. Both methods were effective at choosing locations for wind farms because all the results were statistically significant in the consistency tests. MaxEnt calculated the potential wind energy fields with high accuracy and reliability with 0.915 AUC and LR multiple R square values of 0.883. Compared to the current installed power values, the MaxEnt analysis results were more consistent with the recent status. Izmir has been calculated as the province with the highest potential for wind energy area of 663 km(2) by MaxEnt and 620.4 km(2) by LR.2024-01-01T00:00:00ZInvestigation of possible causes of ionospheric anomalies pre/post-earthquakes based on space weather conditions (SWC)Bulbul, Sercanhttps://hdl.handle.net/20.500.13091/52152024-03-16T09:49:30Z2024-01-01T00:00:00ZTitle: Investigation of possible causes of ionospheric anomalies pre/post-earthquakes based on space weather conditions (SWC)
Authors: Bulbul, Sercan
Abstract: Earthquakes in the world from past to present have caused many loss of life and property. Earthquake forecasting studies are very important in order to prevent destructive effects of these loss of life and property. Total electron content (TEC) is a component that can be easily used to predict natural disasters such as earthquakes. TEC values can be calculated according to the desired location with the help of dual-frequency GNSS receivers and GPS satellites surrounding the whole world. However, it is impossible to predict a possible earthquake with only TEC values. For this purpose, TEC values should be examined together with indices such as space weather conditions indices, and then a possible forecast scenario should be determined. In this study, GPS-TEC anomalies were investigated with possible causes of ionospheric anomalies based on space weather conditions (SWC) indices such as solar activity (EUV and F10.7), geomagnetic activity (Dst), geomagnetic storm (Kp), magnetic field changes (Bz), proton density (Np) changes in the Sivrice-Elazig earthquake (Mw 6.8) that occurred on January 24, 2020, and the Seferihisar (Izmir) earthquakes (Mw 6.6) that occurred on October 30, 2020, in the Aegean Sea off the coast of Seferihisar-Izmir.2024-01-01T00:00:00ZExperimental and numerical investigation of bending performance of prestressed purlins having different longitudinal web openingAksoylu, CeyhunÖzkılıç, Yasin OnuralpÇeledir, EmrullahBaşaran, BoğaçhanArslan, Musa Hakanhttps://hdl.handle.net/20.500.13091/52142024-03-16T09:49:30Z2024-01-01T00:00:00ZTitle: Experimental and numerical investigation of bending performance of prestressed purlins having different longitudinal web opening
Authors: Aksoylu, Ceyhun; Özkılıç, Yasin Onuralp; Çeledir, Emrullah; Başaran, Boğaçhan; Arslan, Musa Hakan
Abstract: Variable cross-section pre-stressed precast concrete purlin (PPCP) members are frequently used in industrial buildings. Lightening these elements, which create a significant weight on the roof plane, is extremely important to reduce both concrete consumption and the weight that will affect the earthquake force. The voids left in the purlin bodies can make them even more economical. A series of experimental and numeric studies were carried out to find an answer to this research question. In the study, 8 PPCP beams with different 1/1 geometric scale web opening ratios (ranging between 7.5%similar to 35% depending on the beam length) were tested. At the end of the experimental study, the openings created in the beams did not significantly reduce the load carrying capacity. In addition, bearing capacity of the reference beam was obtained approximately 17% greater than the calculated analytical value. The results of the tests were validated utilizing ABAQUS FEM. Then, a parametric study was performed on 48 models according to three different pre-stressing levels (0.3 P, 0.6 P and 0.9 P) and three different concrete strengths (30 MPa, 40 MPa and 50 MPa). According to results, especially in PPCP with web opening ratios of 27.5% and 32.5%, both initial stiffness and ductility values increased compared to the reference beam. From the numerical models, it was revelead that the decrease in concrete strength caused a capacity loss of up to 17%, especially in beams with the highest opening ratio. It was discovered that the increase in the pre-stress level increased the stiffness and capacity, but the least increase was in the beam with the highest opening ratio.2024-01-01T00:00:00Z