Scopus İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/8651
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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 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 Diffraction of Cylindrical Waves by a Transmissive Half-Plane(Asme, 2017) Umul, Yusuf Ziya; Ziya Umul, YusufThe scattered acoustic waves by a transmissive half-plane, which is illuminated by a line source, are investigated. The high-frequency diffracted wave expressions are obtained by taking into account a resistive half-screen that is defined in electromagnetics. The uniform diffracted fields are expressed in terms of the Fresnel cylinder functions. The behavior of the waves is compared with the case when the uniform theory of diffraction is considered. The geometrical optics and diffracted fields are examined numerically.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 Citation - WoS: 7Citation - Scopus: 7Diffraction of Waves by a Perfectly Conducting Half-Plane Between Two Dielectric Media(Elsevier, 2014) Umul, Yusuf ZiyaThe scattered fields by a perfectly conducting half-plane, located at the interface of two dielectric media, are investigated. The diffracted fields are defined with novel reflection and transmission coefficients that are functions of the observation distance and angle. These coefficients reduce to the constant reflection and transmission coefficients of the geometrical optics wave. The unknown quantities in the coefficients of the diffracted waves are determined according to the boundary conditions on the half-plane and the interface of the dielectric media. The resultant field expressions are investigated numerically and the behavior of the scattered and diffracted waves are studied. (C) 2013 Elsevier B.V. All rights reserved.Article Citation - WoS: 4Citation - Scopus: 4Transmission of a Bessel Beam Through a Circular Aperture in an Impedance Screen(Iop Publishing Ltd, 2014) Umul, Yusuf ZiyaThe scattering effect of a circular aperture, located in an impedance plane, on a Bessel beam is investigated by decomposing the scattered wave into two subcomponents, namely the geometrical optics and diffracted fields. The diffracted waves are investigated with the aid of the geometrical theory of diffraction. The detour parameter is evaluated and the existence zones of the geometrical optics fields are determined. The various aspects of the reflected and transmitted scattered waves, including the self healing of the beam, are studied numerically.Article The Method of the Boundary Diffraction Wave for Impedance Surfaces(Elsevier, 2012) Umul, Yusuf ZiyaThe line integral of the boundary diffraction wave theory is extended for the diffraction process of waves by the impedance surfaces with edge discontinuities. With this aim, the exact diffraction field expression of Maliuzhinets is transformed into a line integral. The method is applied to the scattering problems of waves by a spherical reflector with edge discontinuity and the diffracted fields are evaluated asymptotically. The resultant expressions of the waves are examined numerically. (C) 2011 Elsevier B.V. All rights reserved.