Browsing by Author "Ziya Umul, Yusuf"

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Citation - WoS: 11
Citation - Scopus: 9
Diffraction of Cylindrical Waves by a Perfectly Conducting Half-Screen: a Modified Theory of Physical Optics Solution
(Wiley-blackwell, 2016) Umul, Yusuf Ziya; Ziya Umul, Yusuf
The scattering problem of waves, radiated by a line source, is investigated by the method of modified theory of physical optics. The solution is obtained for both of the Dirichlet and Neumann boundary conditions. Two dimensional modified theory of physical optics integral is considered, since the problem is symmetric according to one of the spatial coordinates. The scattering integral is directly evaluated and a new function is defined for the scattered fields. The mathematical properties of the function are studied. The total, geometrical optics and diffracted waves are analyzed numerically. (C) 2016 Wiley Periodicals, Inc. View this article online at wileyonlinelibrary.com.
Diffraction of Cylindrical Waves by a Transmissive Half-Plane
(Asme, 2017) Umul, Yusuf Ziya; Ziya Umul, Yusuf
The 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.
Mass Gain and Loss of Non-Relativistic Electrons in Photon-Electron Interactions
(Springer, 2011) Umul, Yusuf Ziya; Ziya Umul, Yusuf
It is shown that the electrons gain mass as their non-relativistic velocities increase. This process is realized by the absorption of photons in the colliding process. In an inverse manner, they loss their mass when they radiate photons. The related equations are derived by using the relativistic mass equation and independently by considering the non-relativistic energy relation. The Compton scattering and photon emission phenomena are revisited with the new theory.
Citation - WoS: 6
Citation - Scopus: 5
A New Representation of the Kirchhoffs Diffraction Integral
(Elsevier Science Bv, 2013) Umul, Yusuf Ziya; Ziya Umul, Yusuf
The diffraction integral of Kirchhoff is rearranged according to its integral boundaries. The new approach is based on the theory of the edge dislocation waves and provides a more correct field representation for the semi-infinite and infinite integrals in the direct numerical computation. The integral is studied on the diffraction problem of plane waves by a perfectly conducting half-plane. The correctness of the scattering diagrams is compared with the classical approach and the Fresnel integral representation of the scattered waves numerically. (c) 2012 Elsevier B.V. All rights reserved.