Elektronik ve Haberleşme Mühendisliği Bölümü Yayın Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/260
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Article Citation - WoS: 1Citation - Scopus: 2Physical Optics Approach To Wave Diffraction by a Perfect Electromagnetic Conductor Half-Plane(Springer, 2021) Umul, Yusuf ZiyaThe scattering of electromagnetic plane waves by a perfect electromagnetic conductor is investigated. The method of physical optics is used for the analysis of the problem. The reflected fields by a whole-plane are taken into account. The surface electric and magnetic current densities are constructed with the aid of the incident wave and the reflected field from the whole-surface. The scattering integrals are obtained for the electric and magnetic vector potentials. The scattered electric and magnetic fields are expressed in terms of the vector potentials. The scattering integrals are evaluated asymptotically for large values of the wave-number. Some numerical results are given.Article Hydrogen hosting of nanoscale boron cluster(Editura Academiei Romane, 2008) Böyükata, Mustafa; Özdoğan, C.; Güvenç, Ziya B.; Bäoyäukata, M.; ÄozdoGan, C.; Gäuvenc, Z.B.In this paper the Density Functional Results of hydrogen bonded boron micro clusters with B3LYP/6-311++G(d,p) level of computations will be presented. Energetics and structural stability with their possible stable geometries of various selected micro complexes of B(m)H(n) (for m and n <= 11 )boron hydrides have been analysed, and their binding energies with HOMO-LUMO energy gaps have been determined. Mainly, erects of the number of hydrogen atoms on the structures of the boranes are assessed. Moreover, for the cage configurations their distortions have been investigated for the neutral, anionic and cationic cases. It has been observed that there have been two opposing factors for the cage configurations. One of which is the "peeling" of the cage structures by the hydrogen atoms, and the other one is reforming a smaller cage form simultaneously with there remaining boron atoms inside. This is observed mostly for the odd values of m. From our studies it has been also observed that with the bare boronclusters alone, it is difficult to increase the capacity of the hydrogen storage. Therefore, further studies are necessary with the boron complexesArticle Citation - WoS: 4Citation - Scopus: 4Boundary Diffraction Wave Theory Approach To Corner Diffraction(Springer, 2019) Umul, Yusuf ZiyaThe scattering process of plane waves by a discontinuous edge contour is studied with the three dimensional boundary diffraction wave theory. The edge and corner diffracted fields are obtained from the stationary phase and edge point evaluations of the line integral. A new corner diffraction coefficient is derived. The behaviors of the uniform edge and corner diffracted waves are investigated numerically.Article Citation - WoS: 22Citation - Scopus: 20The Method of Transition Boundary for the Solution of Diffraction Problems(Springer, 2019) Umul, Yusuf ZiyaA new method, which enables one to solve some diffraction problems, is put forth. The technique is based on a relation between the diffracted and scattered geometric optics waves at the transition boundaries. The concept of initial waves is also used instead of the incident field. The general algorithm of the method is outlined and applied to the diffraction problems of waves by perfect electric conductor half-screen, resistive half-plane and impedance sheet junction.Article Citation - WoS: 6Citation - Scopus: 8Diffraction of Waves by a Perfect Electromagnetic Conductor Half-Plane Between Isorefractive Media(Springer, 2019) Basdemir, Husnu DenizIn this study, diffraction of waves by a perfectly electromagnetic conductor half-plane which is lying at the boundary of isorefractive media is investigated. The diffracted field expressions are constructed by using the relation between scattered geometrical optics fields and the transition boundaries. The high frequency asymptotic expressions of diffracted fields reach infinite magnitude values at the transition boundaries. The uniform expressions of fields are obtained by using the uniform theory of diffraction method in order to obtain the finite magnitude values at the transition boundaries and the results are analyzed numerically for different set of parameters.Article Citation - WoS: 4Citation - Scopus: 5Interaction of Plane Waves by a Half-Screen Between Two Different Media(Springer, 2018) Umul, Yusuf ZiyaThe diffraction process of plane waves by a perfectly electric conducting half-screen, residing at a planar junction between two different media, is investigated. The scattered geometrical optics waves are evaluated by subtracting the initial fields from the total geometrical optics waves. The diffracted waves are obtained from the scattered geometrical optics fields by using a relation at the transition boundaries. The diffracted waves are expressed separately for both of the media. The uniform representations of the diffracted fields are obtained by using the uniform theory of diffraction. The scattered fields are analyzed numerically.Article Citation - WoS: 3Citation - Scopus: 4Edge Diffraction in an Anomalously Reflecting Half-Plane(Springer, 2018) Umul, Yusuf ZiyaA half-plane, formed of anomalously reflecting metasurface, is taken into account. The layer is modeled by an impedance half-screen. In order to obtain the diffracted fields, the geometrical optics waves are evaluated as a sum of equivalent soft, hard and impedance surfaces. The diffracted waves are derived by the superposition of the diffracted fields from the equivalent surfaces. The uniform field expressions are obtained by the method of uniform theory of diffraction. The behaviors of the fields are studied numerically.Article Citation - WoS: 15Citation - Scopus: 13Diffraction of Line Source Field by a Resistive Half-Plane Between Isorefractive Media(Springer, 2017) Umul, Yusuf ZiyaThe scattering process of cylindrical waves by a resistive half-plane, residing at the interface of isorefractive media, is investigated. The uniform expression of the diffracted cylindrical waves by a resistive half-screen is obtained for a single medium. Then the initial fields are found for an interface between isorefractive media. The scattered geometrical optics waves are derived by subtracting the initial fields from the total geometrical optics waves when the resistive half-plane exists at the interface. The diffracted fields are determined by using the scattered geometrical optics waves. The behavior of the resultant waves is analyzed numerically.Article Mass Gain and Loss of Non-Relativistic Electrons in Photon-Electron Interactions(Springer, 2011) Umul, Yusuf Ziya; Ziya Umul, YusufIt is shown that the electrons gain mass as their non-relativistic velocities increase. This process is realized by the absorption of photons in the colliding process. In an inverse manner, they loss their mass when they radiate photons. The related equations are derived by using the relativistic mass equation and independently by considering the non-relativistic energy relation. The Compton scattering and photon emission phenomena are revisited with the new theory.