Elektronik ve Haberleşme Mühendisliği Bölümü

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Citation - Scopus: 1
Relativistic Wave Equation for a Quantum Particle With Potential Energy
(Elsevier Gmbh, 2019) Umul, Yusuf Ziya
A new relativistic wave equation is derived for a quantum particle which moves in a potential. The relativistic equation of energy is reconsidered with the potential energy term. The energy-momentum relation is obtained for this case. The related differential equation is derived by taking into account a wave function in terms of a plane wave. It is shown that the new equation directly reduces to the Schrodinger equation of a particle, moving in a potential in the non-relativistic limit. The wave equation is applied to the interaction of wave function with a potential barrier.
Citation - WoS: 7
Citation - Scopus: 8
Hermite Hyperbolic/Sinusoidal Gaussian Beams in Abcd Systems
(Elsevier Gmbh, 2007) Eyyuboglu, Halil Tanyer
For a Hermite hyperbolic/sinusoidal Gaussian beam with focusing properties, passing through an arbitrarily shaped rectangular aperture on the source plane and an on-axis x-y asymmetric ABCD system, the receiver plane expression is derived using the Collins integral. The specific example of a single thin lens placed on the propagation path is examined at selected source, propagation and optical element parameters. Viewing the progress of the beam in propagation, we find that subjecting the source beam to an aperture will give rise to excessive spreading during propagation. The lens setup will act to concentrate the energy of the beam around its focal point as expected, while in some circumstances it will also execute beam profile changes. By adjusting the aperture opening in the shape of a narrow slit, the beam will become aligned in the opposite direction after propagating after having traveled sufficiently. The results are presented as intensity graphs in the form of contour plots and 3D illustrations. (c) 2006 Elsevier GmbH. All rights reserved.
Modified Theory of Physical Optics Approach To Impedance Surfaces for Skew Incidence
(Elsevier Gmbh, 2020) Umul, Yusuf Ziya
A three dimensional modified theory of physical optics integral is constructed for the impedance surfaces, illuminated by a plane wave for skew incidence. The scalar fields are taken into account. The kernel of the physical optics integral is evaluated by using a relation with the geometric optics waves and stationary phase evaluation of the integral. The obtained surface integral is applied to the diffraction problem of waves by an impedance half-plane. The scattered fields are investigated numerically.
Citation - WoS: 14
Citation - Scopus: 15
Scattering of Electromagnetic Waves by a Perfect Electromagnetic Conductor Half-Screen
(Elsevier Gmbh, 2019) Umul, Yusuf Ziya
The diffraction of plane electromagnetic waves by a perfect electromagnetic conductor half screen is investigated. The total geometrical optics fields are obtained by using the boundary conditions of a perfect electromagnetic conductor surface. A general relation is defined for the scattered fields in terms of waves by soft and hard surfaces. The total scattered field is derived by using this relation. Some numerical simulations are also given.
Citation - WoS: 2
Citation - Scopus: 8
Scattering of Electromagnetic Waves by an Impedance Sheet Junction in Anisotropic Plasma
(Elsevier Gmbh, 2020) Umul, Yusuf Ziya
The diffraction of electromagnetic plane waves by the edge discontinuity of an impedance sheet junction, which is located in an anisotropic plasma, is investigated. The problem is solved by the integral theory of diffraction. The scattering integral is obtained from the scattered geometric optics wave. The diffracted fields are derived by the edge point evaluation of the scattering integral. The evaluated field expressions are analyzed numerically.
Citation - WoS: 1
Citation - Scopus: 1
Application of the Method of Transition Boundary To the Half-Planes With Mixed Boundary Conditions
(Elsevier Gmbh, 2020) Umul, Yusuf Ziya
The scattering problems of waves by soft-hard and hard-soft half-planes are investigated by the method of transition boundary. The functional values at the transition boundaries are found to be identical to the ones for the soft and hard half-screens. It is shown that the factorization process should be applied by also taking into account the boundary conditions besides the principle of reciprocity. The exact diffracted field expressions are obtained for both of the half-planes.
Citation - WoS: 4
Citation - Scopus: 5
Surface Wave Contribution in Physical Optics Type Scattering Integrals
(Elsevier Gmbh, 2020) Umul, Yusuf Ziya
The contribution of the poles in a real valued physical optics integral is investigated. First of all, a complex integral of scattered waves is taken into account. The edge diffracted and surface wave components are evaluated by the methods of saddle point and Cauchy integral theorem. The physical optics integral is constructed with the aid of the asymptotic expressions of the edge diffraction field. A second PO integral is obtained for the surface waves. The theory is applied to an impedance half-plane.
Citation - WoS: 2
Citation - Scopus: 2
Scattering of Electromagnetic Waves by a Perfectly Conducting Half-Screen at the Interface of Two Different Media: E-Polarization
(Elsevier Gmbh, 2019) Umul, Yusuf Ziya
The interaction of electromagnetic waves with a perfectly conducting half-screen, which is residing between two media with different electromagnetic properties, is investigated for electric polarization. The diffracted fields, in two regions, are determined by using a relation between diffraction and scattered geometric optics waves. Additional terms are included in the diffracted waves in order to satisfy the boundary conditions in the interface. The behavior of the total field and its components are analyzed numerically.
Citation - WoS: 12
Citation - Scopus: 13
Three Dimensional Modified Theory of Physical Optics
(Elsevier Gmbh, 2016) Umul, Yusuf Ziya
The 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.
Citation - WoS: 1
Citation - Scopus: 1
Kinetic Energy Based Relativistic First Order Wave Equations
(Elsevier Gmbh, 2019) Umul, Yusuf Ziya
A relativistic wave equation is derived for spin-1/2 particles. The energy relation is taken into account with respect to the kinetic energy term. Two first order differential equations are obtained from the kinetic energy based relativistic equations. The spin information is integrated to the new equations in two alternative forms.
Citation - WoS: 8
Citation - Scopus: 8
Scattering of Plane Waves by a Rational Half-Plane Between Dng Media
(Elsevier Gmbh, 2019) Basdemir, Husnu Deniz
Scattering of plane waves by a hard-soft half-plane which is lying between double negative material is investigated. The diffracted fields are determined by dividing the diffraction coefficient to four subfields for satisfying the boundary conditions. It is observed that the shadow boundary shifts towards to lower surface of the half-plane. Also geometric optics fields are determined by using the geometry of the problem. As a result, the behavior of the fields is investigated numerically.
Citation - WoS: 19
Citation - Scopus: 17
Effects of Liver Tissue Turbulence on Propagation of Annular Beam
(Elsevier Gmbh, 2018) Baykal, Yahya; Gokce, Muhsin Caner
Effects of tissue turbulence on the propagation properties of an annular laser beam is examined. In this respect, the average intensity profile and the beam spread at the observation plane are formulated and evaluated after the annular laser beam propagates through the turbulent liver tissue. In our formulation, the extended Huygens-Fresnel method is utilized with the involvement of the turbulence power spectrum of the liver tissue. Results obtained from the performed simulations include the variations of the received average intensity and the effective beam size of the annular beam against the changes in the liver tissue turbulence and the laser beam parameters, i.e., against the laser wavelength, tissue length, primary and secondary source sizes of the annular laser beam. Our work in this paper will prove to be helpful in obtaining clues to diagnose abnormalities such as cancer and tumor in a liver tissue.
Citation - WoS: 1
Citation - Scopus: 1
The Relation Between Wave Vector and Momentum in Quantum Mechanics
(Elsevier Gmbh, 2016) Umul, Yusuf Z.
The fundamental relation of quantum mechanics, which correlates the momentum of a quantum particle to the wave vector of the matter wave, is re-interpreted. The wave vector, in the relation, is formulized as the integration of it along the angular coordinates for two and three dimensional cases. Various evaluations of the wave vector are performed for different types of waves and the results are discussed. Also the edge diffracted fields are considered according to the new interpretation. (C) 2016 Elsevier GmbH. All rights reserved.
Citation - WoS: 2
Citation - Scopus: 1
Airy-Type Relativistic Matter Wave
(Elsevier Gmbh, 2021) Umul, Yusuf Ziya
A new relativistic Airy-type matter wave is introduced as a solution of the kinetic energy based wave equation. The parametric solution of the related differential equation is obtained. The total energy and momentum of the relativistic particle are derived by using a Bohmian type of decomposition of the kinetic energy based equation. The acceleration of the particle is also evaluated. The behavior of the matter wave is investigated numerically.
Citation - WoS: 9
Citation - Scopus: 11
Wave Diffraction by a Perfect Electromagnetic Conductor Wedge
(Elsevier Gmbh, 2019) Umul, Yusuf Ziya
The scattering of plane electromagnetic waves by a perfect electromagnetic conductor wedge is investigated. The diffraction coefficient of the wedge is obtained by considering the structure of the scattered waves by a whole perfect electromagnetic conductor plane and the diffraction coefficients of the soft and hard wedges. The behavior of the total, total geometric optics and uniform diffracted waves are analyzed numerically.
Scattering of Electromagnetic Waves by a Perfectly Conducting Wedge for Grazing Incidence
(Elsevier Gmbh, 2019) Umul, Yusuf Ziya
The diffraction phenomenon of electromagnetic waves by a perfect electric conductor and perfect magnetic conductor wedges is investigated for the grazing incidence. It is shown that the rigorous solution does not reduce to the correct diffraction fields when the angle of incidence is zero according to the one of the faces of wedge. A new expression is obtained by dividing the high-frequency asymptotic diffracted field expression into four parts. Some numerical results are given.
Citation - WoS: 5
Citation - Scopus: 6
Scattering of Waves by a Half-Screen Between Isorefractive Media
(Elsevier Gmbh, 2018) Umul, Yusuf Ziya
The scattering process of plane electromagnetic waves by a perfectly conducting half-plane, residing between isorefractive media, is investigated. The semi-infinite interface between two different media is modeled by using a resistive surface, since it causes the reflection and transmission of the incident wave. Thus the scenario is reduced to the diffraction problem of waves by the junction of two half-screens. The diffracted field is expressed with the aid of the split function that occurs in the Wiener-Hopf factorization of the scattered waves by imperfectly conducting half-planes. The total, geometrical optics and diffracted waves are analyzed numerically. (C) 2017 Elsevier GmbH. All rights reserved.
Citation - WoS: 3
Citation - Scopus: 5
On the Reality of the Bohmian Potential
(Elsevier Gmbh, 2020) Umul, Yusuf Ziya
The existence of the Bohmian quantum potential is investigated in terms of the energy relation of a quantum particle. The derivation process of the quantum potential is applied to the Helmholtz equation and it is shown that a similar term also occurs in this case. The possibility of the existence of a potential term is questioned according to the frequency and wave-number quantities of a wave which is the solution of the Helmholtz equation. By using the same approach, it is shown that the quantum potential should be equal to zero. Some examples are studied in terms of the wave function.
Citation - WoS: 1
Citation - Scopus: 2
The Surface Wave Phenomenon on an Impedance Half-Plane
(Elsevier Gmbh, 2020) Umul, Yusuf Ziya
The excitation of surface waves on an impedance half-plane is investigated by considering the complex integral of scattering. The poles of the split function are examined with respect to some criteria, obtained from an inhomogeneous plane wave. It is shown that two poles of the complex integral lead to null fields. The surface wave expressions were derived according to the remaining two poles. The diffraction of the surface waves at the edge discontinuity of the half-plane is studied by using the theory, developed for grazing incidence. The uniform representation of the diffracted field is performed according to the uniform theory for evanescent waves. The behaviors of the obtained field expressions were examined numerically.
Citation - Scopus: 1
The Factorization Process in the Modified Theory of Physical Optics
(Elsevier Gmbh, 2020) Umul, Yusuf Ziya
The factorization process is integrated to the procedure of the modified theory of physical optics. The scattering integral for the diffraction problem of waves by a soft half-plane is taken into account. The values of the kernel is obtained for two special values of the scattering angle beta. By considering the behavior of the integrand at these special values, a technique for the factorization process is determined. The new approach is applied to the problems of hard, impedance and conductive half-screens.

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