WoS İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/8653
Browse
203 results
Search Results
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 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 Comparative Analysis of Impedance Matching Techniques in Wireless Power Transfer Efficiency: A Focus on Resonant, Adaptive, and Hybrid Approaches(Springer, 2025) Hatem, Sude; Kurt, ErolWireless power transfer (WPT) efficiency is highly dependent on impedance matching; however, comparative analyses of matching techniques under dy namic operating conditions remain limited. This study presents a systematic evaluation of three impedance matching approaches, namely resonant, adaptive, and hybrid, via theoretical modeling and numerical simulations. The results prove that adaptive impedance matching maintains stable efficiency (90.0% +/- 0.9%) in load variations (20-100 Omega ), coil misalignment (0<bold>degrees</bold>-30<bold>degrees</bold>), and transmission distances (0.1-1 cm), with minimal fluctuations. In contrast, resonant matching shows the best efficiency (i.e., 95%) under ideal conditions (10 MHz, 0<bold>degrees</bold> misalignment, 50 Omega load) but degrades rapidly to <50% under deviation conditions (e.g., 30 misalignment or 1 cm distance). The hybrid solution yields a balanced compromise that maintaining 85-92% efficiency in larger operating ranges. Quantitative metrics-the fluctuation rate (adaptive: 0.07 vs. resonant: 0.15) and stability index (adaptive: 102 vs. resonant: 20)-exhibit adaptive matching's superior dynamic performance. These find ings present practical advice on selecting impedance matching techniques in real WPTapplications, such as electric vehicle charging and medical implants, where stability under variability is paramount.Article Citation - WoS: 36Citation - Scopus: 41Numerical Treatment of Coupled Nonlinear Hyperbolic Klein-Gordon Equations(Editura Acad Romane, 2014) Doha, E. H.; Baleanu, Dumitru; Bhrawy, A. H.; Baleanu, D.; Abdelkawy, M. A.; MatematikA semi-analytical solution based on a Jacobi-Gauss-Lobatto collocation (J-GL-C) method is proposed and developed for the numerical solution of the spatial variable for two nonlinear coupled Klein-Gordon (KG) partial differential equations. The general Jacobi-Gauss-Lobatto points are used as collocation nodes in this approach. The main characteristic behind the J-GL-C approach is that it reduces such problems to solve a system of ordinary differential equations (SODEs) in time. This system is solved by diagonally-implicit Runge-Kutta-Nystrom scheme. Numerical results show that the proposed algorithm is efficient, accurate, and compare favorably with the analytical solutions.Article Citation - WoS: 60Citation - Scopus: 68Lyapunov-Krasovskii Stability Theorem for Fractional Systems With Delay(Editura Acad Romane, 2011) Baleanu, Dumitru; Baleanu, D.; Ranjbar N, A.; Abdeljawad, Thabet; Sadati R, S. J.; Delavari, R. H.; Abdeljawad (Maraaba), T.; Gejji, V.; MatematikFractional calculus techniques and methods started to be applied during the last decades in several fields of science and engineering. In this paper we studied the stability of fractional order nonlinear time-delay systems for Caputo's derivative and we extended Lyapunov-Krasovskii theorem for the fractional nonlinear systems.Article Citation - WoS: 19Citation - Scopus: 18On Fractional Coupled Whitham-Broer Equations(Editura Acad Romane, 2011) Kadem, Abdelouahab; Baleanu, Dumitru; Baleanu, Dumitru; MatematikFinding the fractional version of a given classical nonlinear equation or to a given system of differential equations is still an open problem in the field of the fractional calculus. In this paper the homotopy perturbation method is used to find an analytical approximate solution for the coupled Whitham-Broer-Kaup equations. The obtained results indicate that the method is efficient and accurate.Article Citation - WoS: 34Citation - Scopus: 38On the Fractional-Order Diffusion-Wave Process(Editura Acad Romane, 2010) Herzallah, Mohamed A. E.; Baleanu, Dumitru; El-Sayed, Ahmed M. A.; Baleanu, Dumtru; MatematikOne of the main applications of the fractional calculus, integration and differentiation of arbitrary orders is the modelling of the intermediate physical processes. Here we formulate a more general model which represents the diffusion wave process in all its cases, and give some examples discussing these different cases.Article Citation - WoS: 19Citation - Scopus: 18New Results for Multidimensional Diffusion Equations in Fractal Dimensional Space(Editura Acad Romane, 2016) Ma, Min; Baleanu, Dumitru; Baleanu, Dumitru; Gasimov, Yusif S.; Yang, Xiao-Jun; MatematikThe multidimensional diffusion equations in fractal dimensional space started to play an important role in physics. In this paper we present the analytical solutions of the multidimensional diffusion equations in fractal dimensional spaces by using the method of separation of variables. The graphs of the exact solutions are presented and the accuracy and efficiency of the approach are revealed for a class of local fractional partial differential equations.Article Citation - WoS: 28Citation - Scopus: 33Lagrangian Formulation of Maxwell's Field in Fractional D Dimensional Space-Time(Editura Acad Romane, 2010) Muslih, Sami I.; Baleanu, Dumitru; Saddallah, Madhat; Baleanu, Dumitru; Rabei, Eqab; MatematikThe Lagrangian formulation for field systems is obtained in fractional space-time fractional dimensions D = D-space + D-time. The equations of motion for Maxwell's field are obtained. It is shown that the form of Maxwell's equations in fractional dimensional space are not invariant and they can be solved in the same manner as in the integer space-time dimensions.Article Citation - WoS: 11Citation - Scopus: 12Uniqueness and Existence of Positive Solutions for Singular Fractional Differential Equations(Texas State Univ, 2014) Nyamoradi, Nemat; Baleanu, Dumitru; Bashiri, Tahereh; Vaezpour, S. Mansour; Baleanu, Dumitru; MatematikIn this article, we study the existence of positive solutions for the singular fractional boundary value problem [GRAPHICS] where 1 < alpha <= 2, 0 < xi <= 1/2, a is an element of [0, infinity), 1 < alpha - delta < 2, 0 < beta(i) < 1, A, B-i, 1 <= i <= k, are real constant, D-alpha is the Reimann-Liouville fractional derivative of order alpha. By using the Banach's fixed point theorem and Leray-Schauder's alternative, the existence of positive solutions is obtained. At last, an example is given for illustration.