WoS İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/8653
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Article Citation - WoS: 5Citation - Scopus: 5Exact Form of the Physical Optics Integral(Elsevier Gmbh, Urban & Fischer verlag, 2017) Umul, Yusuf ZiyaThe exact structure of the physical optics integral is obtained. With this aim, the rigorous solution of the diffraction problem of waves by a perfectly conducting half-plane is considered. The Fresnel integrals of the incident and reflected scattered fields are transformed into the physical optics integrals by defining a suitable variable transform. The relation of the obtained integral with the modified theory of physical optics is discussed. (C) 2016 Elsevier GmbH. All rights reserved.Article Citation - WoS: 4Citation - Scopus: 5Wave Diffraction by a Soft/Hard Strip: Modified Theory of Physical Optics Solution(Elsevier Gmbh, Urban & Fischer verlag, 2018) Umul, Yusuf ZiyaThe scattering problem of waves by a strip, the faces of which are composed of soft and hard surfaces, is investigated by the method of modified theory of physical optics. The scattering integral is divided into two parts according to the single effects of the faces. The boundary conditions are integrated into the integrals and the resultant field expressions are obtained by the asymptotic evaluation methods. The scattered waves are examined numerically. (C) 2017 Elsevier GmbH. All rights reserved.Article Citation - WoS: 17Citation - Scopus: 17Integral Theory of Diffraction for Material Junctions(Elsevier Gmbh, Urban & Fischer verlag, 2017) Umul, Yusuf ZiyaA new approach to the scattering problem of waves by junctions is developed with the aid of the modified theory of physical optics (MTPO). The relation between the fundamental MTPO integral and the Fresnel function is given as a theorem with its proof. Then the integrals relation with the geometrical optics (GO) and diffracted waves is put forth with a theorem on the uniform asymptotic evaluation of scattering integrals. A new definition is introduced for the scattering process and it is shown that the solutions of some problems, related with material half-planes and junctions can be obtained easily by only evaluating the GO fields according to the new definition of the scattering phenomenon. The scattered and diffracted fields can be derived directly in terms of the MTPO integrals as a result of the relation between the GO and scattered waves. The resultant diffracted field expressions are investigated numerically. (C) 2016 Elsevier GmbH. All rights reserved.Article Citation - Scopus: 1Diffraction of Waves by a Conductive Half-Plane(Elsevier Gmbh, Urban & Fischer verlag, 2017) Umul, Yusuf ZiyaThe scattering process of plane waves by a conductive half-plane is investigated. The scattered geometrical optics waves are obtained by subtracting the incident field from the total geometrical optics waves. The physical optics integral is constructed from the scattered geometrical optics fields. The diffracted waves are evaluated by the application of the edge point method to the physical optics integral. A correction field is added to the diffracted waves in order to satisfy the conductive boundary conditions on the surfaces of the half plane. The uniform diffracted fields are evaluated and the resultant scattered waves are compared with the literature numerically. (C) 2016 Elsevier GmbH. All rights reserved.Article Wave Diffraction by a Metallic Half-Plane(Elsevier Gmbh, Urban & Fischer verlag, 2016) Umul, Yusuf ZiyaThe scattering problem of plane waves by a half-screen with different face impedance is obtained with a geometrical optics-physical optics based method. The kernel of the physical optics integral is redefined by using coefficients that guarantee the satisfaction of the boundary condition on the surface of the scatterer. The uniform diffraction fields are obtained and the behavior of the scattered waves is investigated numerically for different values of the surface impedance. (C) 2015 Elsevier GmbH. All rights reserved.Article Citation - WoS: 3Citation - Scopus: 3The Mtpo/Malyughinetz Hybrid Method for the Scattering Analysis of Parabolic Impedance Reflectors(Elsevier Gmbh, Urban & Fischer verlag, 2013) Umul, Yusuf ZiyaThe scattering process of cylindrical waves, radiated by a line source, from a parabolic reflector is investigated with the MTPO/Malyughinetz hybrid method. The geometrical optics and diffracted waves are evaluated asymptotically from the radiation integral. The scattered, diffracted and geometrical optics waves are plotted numerically for different impedance values. (C) 2013 Elsevier GmbH. All rights reserved.Article Scattering of Waves by an Aperture in an Impedance Screen(Elsevier Gmbh, Urban & Fischer verlag, 2012) Umul, Yusuf ZiyaThe transmission and diffraction of waves by an aperture in an impedance screen is investigated. The Senior's solution of the scattering problem of waves by an impedance half-plane is transformed into a physical optics type integral. The obtained method is applied to the transmission problem of waves by a slit in an impedance screen. The results are compared with the aperture problem in black and conducting screens numerically. (C) 2012 Elsevier GmbH. All rights reserved.Article Citation - WoS: 5Citation - Scopus: 5Fringe Waves in Wedge Diffraction(Elsevier Gmbh, Urban & Fischer verlag, 2012) Umul, Yusuf Z.Explicit expressions for the non-uniform currents of the physical theory of diffraction are derived in terms of Fresnel functions for wedge diffraction by taking into account the surface integrals of the modified theory of physical optics. The obtained fringe waves are compared numerically by the asymptotic representations, found in the literature. (C) 2011 Elsevier GmbH. All rights reserved.