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: 7Citation - Scopus: 9Rubinowicz Transform of the Mtpo Surface Integrals(Elsevier Science Bv, 2008) Umul, Yusuf Z.The surface integral of the modified theory of physical optics is reduced to a line integral by using the Rubinowicz transform for the incident scattered fields by an arbitrary aperture in a black surface. The integral theorem of Kirchhoff is applied to the scattering geometry and the diffracted fields are expressed in terms of a line integral along the contour of the diffracting edge. (C) 2008 Elsevier B.V. All rights reserved.Article Citation - WoS: 12Citation - Scopus: 13Three Dimensional Modified Theory of Physical Optics(Elsevier Gmbh, 2016) Umul, Yusuf ZiyaThe three dimensional version of the modified theory of physical optics is introduced with the aid of a Green's function that satisfies the Helmholtz equation in local spherical coordinates. The algorithm which leads to the construction of the scattering integral is given. The method is applied to the three dimensional diffraction problem of plane waves by a perfectly conducting half-plane. The comparison of the resulting field expressions with the literature shows that the modified theory of physical optics leads to the exact solution. (C) 2015 Elsevier GmbH. All rights reserved.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: 12Citation - Scopus: 13The Relation Between the Boundary Diffraction Wave Theory and Physical Optics(Elsevier Science Bv, 2008) Umul, Yusuf Z.The physical optics surface integral is asymptotically reduced to a line integral along the contour of the diffracting edge. It is shown that the resultant integral can be separated into two sub-integrals which represent the reflected and transmitted diffracted fields. The integrands are transformed into the same forms with the potential function of the boundary diffraction wave theory. (C) 2008 Elsevier B.V. All rights reserved.