Scopus İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/8651
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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: 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: 3Citation - Scopus: 4General Formulation of the Edge-Diffracted Paraxial Waves(Elsevier Sci Ltd, 2009) Umul, Yusuf Z.A general formula for edge-diffracted paraxial waves is derived in terms of the Fourier integral transform. It is observed that the scattered paraxial wave can be divided into components of the geometrical optics and diffracted fields in the spectral domain. An edge-diffracted Gaussian beam is examined numerically as an application of the formula. (C) 2008 Elsevier Ltd. All rights reserved.Article Citation - WoS: 11Citation - Scopus: 11Uniform Theory of the Boundary Diffraction Wave(Elsevier Sci Ltd, 2009) Umul, Yusuf Z.A uniform version of the potential function of the Maggi-Rubinowicz boundary diffraction wave theory is obtained by using the large argument expansion of the Fresnel integral. The derived function is obtained for the problem of diffraction of plane waves by a circular edge. The results are plotted numerically. (c) 2008 Elsevier Ltd. All rights reserved.