Browsing by Author "Umul, Yusuf Ziya"

Now showing 1 - 20 of 113

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: 3
Citation - Scopus: 3
A Hybrid Maliuzhinets/Po Method for Diffraction Problems by Impedance Wedges
(Elsevier Science Bv, 2011) Umul, Yusuf Ziya
The solution of Maliuzhinets of the diffraction problem of waves by an impedance wedge is transformed into a physical optics integral. The resultant expression is suitable for the investigation of various diffraction problems having impedance wedges. The method is applied to the scattering of waves by an impedance spherical reflector with wedge structure at its discontinuity. The results are examined numerically. (C) 2011 Elsevier B.V. All rights reserved.
Citation - WoS: 1
A Uniform Function for the Diffraction of Spherical Waves
(Elsevier Gmbh, Urban & Fischer verlag, 2017) Umul, Yusuf Ziya
A function which occurs in the scattering problem of the spherical waves by a perfectly conducting half-plane is introduced for constructing the transition functions of the uniform theory of diffraction and uniform asymptotic theory of diffraction. The important properties of the function, related with the geometrical optics and diffracted field components, are derived mathematically. A uniform asymptotic theory of wedge diffraction is introduced based on the new function. The resultant field expressions-are investigated numerically. (C) 2016 Elsevier GmbH. All rights reserved.
Citation - WoS: 5
Citation - Scopus: 5
Boundary Diffraction Wave Theory of Junctions Between Two Surfaces With Different Face Impedances
(Elsevier Sci Ltd, 2012) Umul, Yusuf Ziya
The line integral of the boundary diffraction wave theory is derived for the diffraction process of waves by a junction between two surfaces with different face impedances. The exact solution of Maliuzhinets is used with this aim. The resultant integral is applied to the diffraction of waves by a circular junction between two impedance surfaces. The results are examined numerically. (C) 2011 Elsevier Ltd. All rights reserved.
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: 2
Citation - Scopus: 2
Diffraction by Material Half-Planes for Grazing Incidence
(Elsevier Gmbh, Urban & Fischer verlag, 2018) Umul, Yusuf Ziya
It is shown that the actual solutions of the diffraction problem of waves by material half planes do not reduce to the correct diffracted field expressions for grazing incidence. The correct expressions are obtained for the diffracted waves by resistive and conductive half screens. The case for the impedance half-plane directly emerges in terms of the diffracted fields by the previous two semi-screens. The behaviors of the geometric optics and diffraction waves are investigated numerically. (C) 2017 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: 4
Citation - Scopus: 5
Interaction of Plane Waves by a Half-Screen Between Two Different Media
(Springer, 2018) Umul, Yusuf Ziya
The diffraction process of plane waves by a perfectly electric conducting half-screen, residing at a planar junction between two different media, is investigated. The scattered geometrical optics waves are evaluated by subtracting the initial fields from the total geometrical optics waves. The diffracted waves are obtained from the scattered geometrical optics fields by using a relation at the transition boundaries. The diffracted waves are expressed separately for both of the media. The uniform representations of the diffracted fields are obtained by using the uniform theory of diffraction. The scattered fields are analyzed numerically.
Citation - WoS: 4
Citation - Scopus: 5
Wave Diffraction by a Soft/Hard Strip: Modified Theory of Physical Optics Solution
(Elsevier Gmbh, Urban & Fischer verlag, 2018) Umul, Yusuf Ziya
The scattering problem of waves by a strip, the faces of which are composed of soft and hard surfaces, is investigated by the method of modified theory of physical optics. The scattering integral is divided into two parts according to the single effects of the faces. The boundary conditions are integrated into the integrals and the resultant field expressions are obtained by the asymptotic evaluation methods. The scattered waves are examined numerically. (C) 2017 Elsevier GmbH. All rights reserved.
Diffraction Theory of Waves by Resistive Surfaces
(2010) Umul, Yusuf Ziya; Yalçın, Uğur
Diffraction of scalar plane waves by resistive surfaces are investigated by defining a new boundary condition in terms of the Dirichlet and Neumann conditions. The scattering problems of waves by a resistive half-plane and the interface between resistive and perfectly magnetic conducting half-planes are examined with the developed method. The resulting fields are plotted numerically. The numerical results show that the evaluated field expressions are in harmony with the theory.
Citation - WoS: 4
Citation - Scopus: 5
The Theory of the Boundary Diffraction Wave
(Elsevier Academic Press inc, 2011) Umul, Yusuf Ziya
Comparison of physical optics integral and exact solutions for cylinder problem
(2003) Umul, Yusuf Ziya; Yengel, Emre; Aydın, Ayhan
The sound source composition of the urban sound environment varies depending on the geography and socio-cultural context. Current sound taxonomies in the literature categorize urban sound sources by their source types (e.g., human-made, natural, electromechanical) and respective semantic attributes. This study aims to add another taxonomical layer to the existing urban sound source categorization methods. The additional layer is a recently proposed sound source classification framework (CLIC). The CLIC framework identifies sound sources based on their Diegesis and Intention parametric attributes. The former parametric attribute, diegesis, was derived from film sound design. The geographical and socio-cultural context of the built environment can be considered as its narrative; hence, every event that happens within the functional context can be called diegetic, while the events that do not belong to that specific place can be called nondiegetic. The latter parametric attribute, intention, was derived from product design. One of the prominent sound source categorization methods in product sound design is to group the product emitted sounds as consequential and intentional. Combining these two parametric attributes with the existing taxonomies, the CLIC framework outputs a place-specific design guideline, clearly dictating the actions a sound designer should take. The two parametric attributes group the sound sources under four distinct areas, which dictates the degree of influence of designers on the specific sound source. The four zones are defined as the creation zone, limitation zone, isolation zone, and control zone. Each zone dictates step-by-step sound design instructions for the sound designer. This study consists of two main phases: field recordings and web-based listening tests. The sound sources present in the urban sound environment were identified in the field recordings phase. Later, in the web-based listening tests phase, the identified sound sources were evaluated based on the CLIC framework, and hence, their respective zones on the model were identified. The outcomes of the study propose clear step-by-step design guidelines and present action suggestions for environmental sound designers.
Wave Diffraction by Material Half-Planes
(Elsevier Gmbh, Urban & Fischer verlag, 2017) Umul, Yusuf Ziya
The diffraction of E-polarized electromagnetic waves by resistive and conductive half planes is studied. The solution of Maliuzhinets for the scattering problem of plane waves from an impedance half-screen is taken into account. The diffracted fields from the resistive and conductive half-planes are obtained by using a relation between the scattered waves from material surfaces. The integrals ofscattering are also constructed in the complex plane. The resultant field expressions are compared with the literature numerically. (C) 2016 Elsevier GmbH. All rights reserved.
Scattering of Waves by an Aperture in an Impedance Screen
(Elsevier Gmbh, Urban & Fischer verlag, 2012) Umul, Yusuf Ziya
The transmission and diffraction of waves by an aperture in an impedance screen is investigated. The Senior's solution of the scattering problem of waves by an impedance half-plane is transformed into a physical optics type integral. The obtained method is applied to the transmission problem of waves by a slit in an impedance screen. The results are compared with the aperture problem in black and conducting screens numerically. (C) 2012 Elsevier GmbH. All rights reserved.
Citation - WoS: 1
Citation - Scopus: 1
Physical Optics Based Simple Expressions for Diffracted Waves by Transmissive Half-Planes
(Elsevier Gmbh, Urban & Fischer verlag, 2018) Umul, Yusuf Ziya
The diffracted fields by resistive and conductive half-screens, which transmit a portion of the incident wave and reflect the remaining part, are expressed in terms of simple expressions that are based on the diffraction coefficient of an impedance half-plane. Also alternative representations are derived for the diffracted fields and their effects are studied for different values of surface parameters. The results are examined numerically. (C) 2018 Elsevier GmbH. All rights reserved.
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: 4
Uniform Asymptotic Theory for the Edge Diffraction of Cylindrical Waves
(inst Engineering Technology-iet, 2017) Umul, Yusuf Ziya
The uniform asymptotic theory of diffraction is reintroduced in terms of the Fresnel cylinder function for the diffraction problems of cylindrical waves. The transition function of the above theory, which compensates the discontinuities of the diffracted wave, is constructed according to the new function. The scattering problem of waves by a resistive half-plane is studied by the aid of the improved method. The uniform wave expressions are compared with the ones, obtained by the Fresnel integral at the near and far fields of the edge.
Citation - WoS: 2
Citation - Scopus: 3
Diffraction in Time of an Entangled Non-Relativistic Quantum Particle
(Iop Publishing Ltd, 2021) Umul, Yusuf Ziya
The diffraction process of an entangled non-relativistic quantum particle in time domain is investigated. The scenario consists of two entangled spin-0 particles and a quantum shutter, which is opened at an initial time. The particles are traveling in two opposite sides and expressed with a single wave function. The integral solution of the Schrodinger equation is considered for two particles case. The initial condition is expressed in terms of an entangled wave function. The time-diffracted matter wave is obtained in terms of the Fresnel integral. The effect of the phenomenon of diffraction in time is examined numerically for the entangled system of two particles.
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.
Diffraction of Waves by a Wedge With Phase Conjugate Faces
(2011) Umul, Yusuf Ziya
The scattering process of waves by a wedge with phase conjugate faces is investigated with the aid of the modified diffraction theory of Kirchhoff. The scattering integral is evaluated asymptotically. The uniform diffracted waves and geometrical optics fields are plotted and examined numerically.