http://hdl.handle.net/20.500.12416/410 Elektrik Elektronik Mühendisliği Bölümü yayınlarını içerir. 2026-10-28T16:04:24Z http://hdl.handle.net/20.500.12416/8487 Multimode beam propagation through atmospheric turbulence Gökçe, Muhsin Caner; Baykal, Yahya; Ata, Yalçın; Gerçekcioğlu, Hamza The investigation focuses on studying the propagation characteristics of multimode lasers in the turbulent amosphere. By employing the Huygens-Fresnel integral, we develop analytical formulations for various propagation parameters. These include the average intensity distribution, kurtosis parameter, beam spread, and the average transmittance of multimode beams in turbulent atmosphere. Our findings reveal that as the propagation distance or the structure constant of the atmosphere increases, i.e., turbulence becomes stronger, the kurtosis parameter and the beam spread increase. The multimode beam exhibits a Gaussian like intensity profile when the propagation distance is significantly increased or when the structure constant becomes sufficiently large. For the case of the Gaussian beam, the kurtosis parameter is found to be 3. The multimode beam's kurtosis parameter rises as the turbulence becomes stronger and eventually approaches 3. Raising the mode content leads to a rise in the average transmittance; however, it leads to a decline in the Kurtosis parameter and the beam spread. 2024-02-01T00:00:00Z http://hdl.handle.net/20.500.12416/8443 Depth dependence of oceanic turbulence optical power spectrum under any temperature and salinity concentration Gerçekcioğlu, Hamza; Baykal, Yahya The Oceanic Turbulence Optical Power Spectrum (OTOPS) with depth variations is acquired under any temperature and salinity concentration. It is supposed that specific medium is the Atlantic Ocean at high latitude and the Pacific Ocean at high, mid and low latitudes. For the OTOPS model, a depth-varying functions that include low-latitude, high- and mid-latitude-summer and mid-latitude-winter salinity and temperature changes are found. With the help of the equations for the temperature and salinity changes, figures are obtained for the eddy diffusivity ratio depth of seawater and OTOPS model against the depth and κ at these media. In the ocean, downlink (uplink) is defined as the optical wireless communication link where the receiver (transmitter) is located at a deeper point than the transmitter (receiver), i.e., in the downlink, optical signal proceeds from a point close to ocean surface to deeper ocean and in the uplink, optical signal proceeds from deeper ocean to a point close to ocean surface. In this paper, the OTOPS model is investigated on how its properties change in the underwater environment in downlink and uplink. Different behavior of the OTOPS model is exhibited. 2024-04-01T00:00:00Z http://hdl.handle.net/20.500.12416/8439 Cost optimization of oil type distribution transformer using multi-objective genetic algorithm Telli, Simay; İskender, İres; Yükselen, Emir The demand for electrical energy is increasing day by day with the development of technology in the world. Distributing electric energy to all regions that need energy is a principal issue, and this necessitates the use of transformers to convert the voltage to the desired level. Accordingly, the use of transformers, one of the electrical devices converting AC voltage level at a defined frequency has grown significantly. In this study, design parameters of a 25 kVA, 33/0.4 kV, Yzn11, oil-type distribution transformer are optimized using the Multi-Objective Genetic Algorithm (MOGA) technique by decreasing the weight of the significant materials and manufacturing cost. Electromagnetic analysis of the transformer is performed with ANSYS Maxwell based on the design results obtained from the optimization study for validation of the method. The experimental design parameters are also compared with the optimization results. It is observed that optimum results are achieved by using the proposed approach. 2024-03-31T00:00:00Z http://hdl.handle.net/20.500.12416/8437 Correlations of multimode optical incidences in a turbulent biological tissue Baykal, Yahya; Gökçe, Muhsin Caner; Gerçekcioğlu, Hamza; Ata, Yalçın In a turbulent biological tissue, field correlations at the observation plane are found when a multimode optical incidence is used. For different multimode structures, variations of the multimode field correlations are evaluated against the biological tissue turbulence parameters, i.e., the strength coefficient of the refractive-index fluctuations, fractal dimension, characteristic length of heterogeneity, and the small length-scale factor. Using a chosen multimode content, for specific biological tissue types of liver parenchyma (mouse), intestinal epithelium (mouse), upper dermis (human), and deep dermis (mouse), field correlations are evaluated versus the strength coefficient of the refractive-index fluctuations and small length-scale factor. Again, with a chosen multimode content, behavior of the field correlations is studied against the strength coefficient of the refractive-index fluctuations for various diagonal lengths and the transverse coordinate at the observation plane. Finally, the field correlation versus the strength coefficient of the refractive-index fluctuations is reported for different single modes, which are special cases of multimode excitation. This topic is being reported in the literature for the first time, to our knowledge, and the presented results can be employed in many important biological tissue applications. 2023-01-01T00:00:00Z