WoS İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/8653
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Article Comparison of Diffraction Methods for Lunar Occultations(Elsevier Gmbh, 2020) Umul, Yusuf Z.The only analytical method, which is used for the mathematical analysis of lunar occultations, is the Fresnel diffraction. The Fresnel integral is derived from the diffraction integral of Kirchhoff under some approximations. This paper aims to compare this method with the exact solution of Sommerfeld, which is obtained for a perfect electric conductor half-plane. The geometrical optics and diffracted fields are expressed separately. Numerical simulations are given for the comparison of two different total and diffracted waves.Article Citation - WoS: 2Citation - Scopus: 2Scattering of a Bessel Beam by a Resistive Disc(Elsevier Gmbh, Urban & Fischer verlag, 2017) Umul, Yusuf Z.Bessel beam has two important advantages that make it preferable for the illumination process of biological samples in microscopy. These are the properties of non-diffraction and self-healing. In this paper, the interaction of the zeroth order Bessel beam with a resistive disc, which models a cell or tissue, is investigated by using the uniform geometrical theory of diffraction. The geometrical optics and diffracted waves are evaluated. The scattering characteristics of the beam and the property of self-healing are studied numerically for different values of the surface resistivity. (C) 2016 Elsevier GmbH. All rights reserved.Article Citation - WoS: 1Citation - Scopus: 1Scattering of Waves by a Half-Screen With Different Face Impedances: Closed Form Series Solution(Taylor & Francis Ltd, 2013) Umul, Yusuf Z.A novel series solution is obtained for the scattering problem of waves by a half-plane with different face impedances. The impedance condition is expressed in terms of the sum of Dirichlet and Neumann conditions, multiplied by appropriate coefficients. The scattering problem of plane waves by an interface between two half-planes with different impedances is also investigated. The results are compared with the literature, numerically.Article Citation - WoS: 15Citation - Scopus: 15Diffraction of Waves by a Resistive Half-Plane(Elsevier Science Bv, 2014) Umul, Yusuf Z.The scattered waves by a resistive half-plane are investigated with defining reflection and transmission coefficients for the diffracted waves. The coefficients are determined according to suitable conditions that are derived from the boundary conditions and the limiting cases of the reflection and transmission coefficients of the geometrical optics fields. The resultant field expressions are examined and compared with the literature numerically. (C) 2014 Elsevier By All rights reserved.Article Citation - WoS: 2Citation - Scopus: 2Diffraction of Plane Waves by the Interface Between Black and Soft/Hard Semi-Planes(Elsevier Gmbh, 2012) Umul, Yusuf Z.A theory of scattering, based on the non-perturbation of the incident field, is developed for the black bodies. The method is applied to the diffraction problem of plane waves by an interface between the black and soft/hard half-planes. The solutions are obtained in terms of infinite series and then transformed into Fresnel integrals. The scattered fields are investigated numerically. (C) 2011 Elsevier GmbH. All rights reserved.Article Citation - WoS: 2Citation - Scopus: 2Scattering of Plane Waves by a Wedge With Different Face Impedances(Elsevier Gmbh, 2012) Umul, Yusuf Z.The scattering process of plane waves by a wedge with different face impedances is examined in terms of the closed form series solution. A new boundary condition is derived using the solution of the reflection problem of plane waves by an impedance plane. The series solution is obtained for the wedge problem. The results are investigated numerically. (C) 2011 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.Article Citation - WoS: 4Citation - Scopus: 5Application of the Complex Point Source Method To the Schrodinger Equation(Elsevier Sci Ltd, 2010) Umul, Yusuf Z.The paraxial wave equation is a reduced form of the Helmholtz equation. Its solutions can be directly obtained from the solutions of the Helmholtz equation by using the method of complex point source. We applied the same logic to quantum mechanics, because the Schrodinger equation is parabolic in nature as the paraxial wave equation. We defined a differential equation, which is analogous to the Helmholtz equation for quantum mechanics and derived the solutions of the Schrodinger equation by taking into account the solutions of this equation with the method of complex point source. The method is applied to the problem of diffraction of matter waves by a shutter. (C) 2010 Elsevier Ltd. All rights reserved.Article Citation - WoS: 2Citation - Scopus: 3Wedge Diffraction in Terms of the Method of Physical Optics(Ieice-inst Electronics information Communications Eng, 2009) Umul, Yusuf Z.The method of physical optics is extended for wedge diffraction. The classical integral of physical optics is taken into account for the diffraction problem of plane waves by a conducting half-plane. The integral is decomposed according to the transmitted and reflected scattered waves. The sinusoidal term in the integrand is rewritten by considering the fact that the half-plane is a special case of the wedge. Two cases of soft and hard surfaces are examined and the uniform diffracted waves are obtained by the asymptotic evaluation of the integrals. The results are compared with the literature numerically.