Scopus İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/8651
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Article Random Vibration Analysis of Nuclear Power Plant Structures(Elsevier Science Sa, 2026) Dal, Gizem Caglar; Soyluk, Kurtulus; Çağlar Dal, GizemIn this study, random vibration analysis of a nuclear power plant building under earthquake loading is performed based on a large-magnitude earthquake of Kobe 1995. A typical nuclear power plant structure widely used in China is selected as a numerical model and modeled as a 3D system. Within the scope of the study, random vibration and deterministic analyses were performed on firm, medium, and soft soils to determine the effects of earthquake motions on nuclear power plant systems. In the study, the theory of random vibration analysis based on the filtered white noise (FWN) ground motion model was utilized and it was intended to determine to what extent the FWN model reflects the real earthquake motion. In addition to soil type, the considered power plant system is analyzed for the ground motions showing near-fault and far-fault characteristics. As a result of the study, it is concluded that the FWN ground motion model used to model earthquake ground motion can be used to consider the effect of real earthquakes. It is also underlined that differences in soil type, fault type and analysis methods affect the results for the considered nuclear power plant structure.Article Citation - WoS: 1Scintillation Index in Non-Kolmogorov Jet Engine Exhaust Turbulence(IOP Publishing Ltd, 2026) Baykal, YahyaIn a non-Kolmogorov jet engine exhaust turbulence environment, scintillation index is found and evaluated. Effects of non-Kolmogorov turbulence spectrum, i.e., power law on the scintillations are studied. Variations of the scintillations against the change in the power law are found for various link lengths, structure constants, wave numbers, jet engine exhaust turbulence strengths, source sizes and scale parameters of jet engine exhaust turbulence. When the power law of non-Kolmogorov turbulence varies, the changes in the scintillations in jet engine exhaust turbulence are not large. The results in this paper could be of help to designers of optical wireless communication systems operating in atmosphere experiencing non-Kolmogorov jet engine exhaust turbulence.Article Transmittance of Gaussian Beam in Anisotropic Jet Engine Exhaust Turbulence(Pergamon-Elsevier Science Ltd, 2026) Baykal, YahyaTransmittance is a metric that provides information on how much of the intensity is transferred to the receiver for a given medium. One of the definitions of transmittance is the ratio of the average received intensity in the presence of turbulence to the received intensity in the absence of turbulence. Under such definition, transmittance is found in an anisotropic jet engine exhaust turbulent environment. For various receiver points, transmittances versus the wireless optical communication (WOC) link and anisotropic jet engine exhaust turbulence parameters are presented. The results are useful for designers of WOC links that are installed in the premises such as the airports that possess jet engine exhaust turbulence.Article CFD and DEM Analysis of Cyclone Separator Performance: Implications of Cylinder-to Ratios for Sustainable Engineering(Springer Heidelberg, 2025) Ayli, Ece; Kocak, EyupThis research addresses a common industrial challenge: efficiently separating particles from gas using cyclone separators, a critical component for various applications in sustainable engineering. While several studies have focused on airflow within these separators, this research introduces a novel approach by combining two advanced simulation methods (CFD and DEM) to analyze how different cone heights in a cyclone separator impact its performance. This combined methodology enables the examination of particle movement within the separator, a critical aspect often overlooked in previous studies. By visualizing particle dynamics and analyzing them with DEM, the research underscores the importance of considering particle behavior for obtaining accurate results. Overall, this study enhances our understanding of cyclone separators through state-of-the-art simulations and empirical testing. By elucidating the complex airflow and the influence of geometric design on performance, practical recommendations are provided for the development of more efficient cyclone separators. These improvements can lead to enhanced particle separation and reduced energy consumption, offering significant benefits across multiple industries. The findings reveal that as the conical height-to-total height ratio (h/hc) increases, indicating a more pointed cone, there is a substantial increase in efficiency alongside a minimal and tolerable rise in pressure drop. For instance, at a velocity of 25 m/s, increasing the h/hc ratio from 0.33 to 3 results in a 0.7% reduction in pressure drop and a 14% efficiency increase, contributing to more sustainable operational practices.Article Improved Arithmetic Efficiency in TFHE Through Gate-Level Optimizations(Springer, 2025) Tasel, Faris Serdar; Saran, Ayse NurdanFully homomorphic encryption (FHE) enables computations to be performed directly on encrypted data without decryption, offering a promising solution for privacy-preserving applications, such as secure cloud computing, confidential machine learning, and encrypted analytics. However, one major drawback of FHE is the high computational cost of homomorphic operations, which slows down real-world implementations, making them impractical. This paper explores the implementation of arithmetic operations within the framework of Torus FHE (TFHE) and demonstrates the construction of gate-level optimization for fundamental operations such as addition, subtraction, negation, comparison, and multiplication on fixed-point numbers. Our work emphasizes optimizing arithmetic logic to reduce the number of bootstrapping operations, a critical factor in improving computational efficiency. Furthermore, we investigate the error rates associated with the proposed operations, providing valuable insight into their accuracy and practical applicability. This study contributes to developing more efficient and reliable arithmetic logic for privacy-preserving computations in FHE systems. The experimental results indicate that the proposed optimizations yield speedups of up to 2.27x for addition/subtraction, 3.55x for comparison, and 1.80x for multiplication operations.Article Mitigation of Laser Beam Fluctuation and Performance of Probability of Fade in Weak Ocean Turbulence(Pergamon-Elsevier Science Ltd, 2026) Gercekcioglu, Hamza; Baykal, YahyaUtilizing the Rytov method in weakly turbulent oceanic medium, minimum scintillation index of sinusoidal Gaussian (SG) laser beams, named as the optimum beam (OB), is investigated for the underwater wireless optical communication (UWOC). Horizontal link between any underwater vehicles is considered. The formulation of the on-axis scintillation index of these beams is derived analytically, and the minimum scintillation index is determined with suitable adjustment of the complex displacement parameters. The complex displacement parameters are identified and tabulated for the selected propagation distance and source size. Obtained scintillation index results are drawn against the propagation length and source size. When compared with the plane, spherical, collimated, focused Gaussian, cos-Gaussian and cosh-Gaussian beams, OB is found to possess essential advantage. Additionally, with the obtained scintillation index values, probabilities of fade of these beams are calculated and their behaviors are also presented. OB also has a significant advantage when considering the fade probability.Article Numerical and Experimental Investigation of Effects of Porous Layer on Cooling of Electronic Components(American Society of Mechanical Engineers (ASME), 2026) Kocak, E.; Türkoǧlu, H.In this study, heat transfer and temperature distribution characteristics of an electronic component covered with a porous medium were investigated both experimentally and numerically. An experimental setup was designed and constructed to conduct the experiments. For the numerical analysis, a computational fluid dynamics (CFD) software was developed on the OPENFOAM platform. The experimental results were used to validate the mathematical model and the computer program developed. The validated computer program was used to investigate the effects of Reynolds number, porosity, Darcy number, porous layer sizes, and the channel height on the heat transfer rate from the heat dissipating elements (electronic component) to the flow in wider ranges of the parameters. Using the Nusselt number values obtained both experimentally and numerically, a correlation equation was developed, and an artificial neural network architecture was trained for the Nusselt number. Results show that the Nusselt number increases with increasing Reynolds number, porosity, and the ratio of the height of the porous layer to the channel height. It was observed that the width of the porous medium has no noticeable effect on the Nusselt number. The correlation equation developed with four independent parameters predicts the Nusselt number with an average error of 7.59%. The artificial neural network architecture developed prevails as a more accurate tool, with a maximum error of 1%, for the prediction of the Nusselt number in the range of the parameters considered. © © 2026 by ASME.Article A Generalization of Fixed Point Result of Nonlinear Cirić Type Contraction on Suprametric Spaces(Univ Nis, Fac Sci Math, 2025) Yalcin, Ceylan; Bilazeroglu, SeymaIn this study, the nonlinear technique: (psi,phi)-weak contraction, created by Dutta and Choudhury [6], is used to make the Ciric type contraction nonlinear. Moreover, it is demonstrated that there is unique fixed point in suprametric space for this nonlinear Ciric type contraction.Article Propagation Characteristics of Higher-Order Annular Gaussian Beams in Oceanic Turbulence(Institute of Physics, 2025) Arpali, S.A.; Arpali, Ç.; Baykal, Y.This study aims to explore the propagation characteristics of higher-order annular Gaussian (HOAG) beams in oceanic turbulence. We provide an analytical derivation of the average intensity at the receiver plane based on excitation from a HOAG source field. Additionally, we conduct a detailed analyses of various beam intensity moments including kurtosis parameter, power-in-the-bucket (PIB) and the beam size variation. As oceanic turbulence strength increases, the HOAG beam gradually transforms into a pure Gaussian beam. As the strength of turbulence increases, PIB values for all modes of HOAG beams gradually decrease in an exponential manner until they stabilize, exhibiting behavior similar to that of Gaussian beams. It is also observed that modes of HOAG beams having larger mode numbers carry less energy to the receiver compared to lower-order modes as turbulence strength increases. Analyses of the kurtosis parameter for HOAG beams indicate that during propagation over intermediate distances, there is a tendency for more beam energy to be distributed toward the wings rather than to the center. In contrast, at longer distances, the beam redistributes its energy, resulting in a lower energy concentration in the wings compared to the center. This research can enhance our understanding of the effects of higher-order laser beams, thereby potentially facilitating longer communication distances in underwater wireless optical communication technologies. © 2025 IOP Publishing Ltd.Article Dielectric and Thermal Properties of the Ferroelectric NH4HSO4 Close to Phase Transitions(Elsevier, 2025) Kiraci, A.; Yurtseven, H.This work gives the analysis of the dielectric and thermal properties close to the second order and first order types of ferroelectric-paraelectric phase transitions in ferroelectrics, in particular, NH4HSO4. The power-law formula is used by adapting the Kouvel-Fisher (KF) method describing the magnetization (M) and magnetic susceptibility (chi M) in the case of the spontaneous polarization (PS) and the dielectric constant (& varepsilon;), respectively, in ferroelectric systems. Similar treatment is performed to describe the heat capacity (CP) and the thermal expansivity (proportional to P) close to the phase transitions in NH4HSO4. We show that the variations of PS and & varepsilon; with the temperature near the upper Curie point (TC1 = 270 K) exhibit linearity for the second order transition in NH4HSO4. A linear variation is also obtained between the CP and proportional to P with the temperature close to the lower Curie point (TC2 = 160 K) for the first order transition in this crystal. Experimental data are used from the literature for our analysis. Our approach given here to describe dielectric and thermal properties of NH4HSO4 close to the Curie points, can be applied to some other ferroelectric materials.