Browsing by Author "Yucel, Hazel"

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A Revisit To The Plane Problem For Low-Frequency Acoustic Scattering By An Elastic Cylindrical Shell
(Başkent Üniversitesi Mühendislik Fakültesi, 2024-03-16) Yucel, Hazel; Ege, Nihal; Erbas, Baris; Kaplunov, Julius
The proposed revisit to a classical problem in fluid-structure interaction is due to an interest in the analysis of the narrow resonances corresponding to a low-frequency fluid-borne wave, inspired by modeling and design of metamaterials. In this case, numerical implementations would greatly benefit from preliminary asymptotic predictions. The normal incidence of an acoustic wave is studied for a circular cylindrical shell governed by plane strain equations in elasticity. A novel high-order asymptotic procedure is established considering for the first time all the peculiarities of the low-frequency behavior of a thin fluid-loaded cylinder. The obtained results are exposed in the form suggested by the Resonance Scattering Theory. It is shown that the pressure scattered by rigid cylinder is the best choice for a background component. Simple explicit formulae for resonant frequencies, amplitudes, and widths are presented. They support various important observations, including comparison between widths and the error of the asymptotic expansion for frequencies.
The Effect of Uncertainties in Skin Layers on Photoacoustic Imaging of Skin Cancer
(2020) Yucel, Hazel; Ozdemir, Ozgur; 0000-0001-9617-3747; AAJ-1090-2021
Photoacoustic imaging has started to be used as a new modality for imaging cancerous tissues in layered skin tissue consisting of epidermis, dermis and hypodermis layers. In the imaging algorithms used in photoacoustic imaging, the layered environment Green function is calculated by assuming that the thickness of each layer is known and imaging is performed. However, the value of these layer thicknesses varies from person to person and it is not possible to know the actual values during imaging. In this study, what kind of errors in the estimation of skin layer thicknesses will lead to the errors in photoacoustic imaging is investigated by using Back-projection imaging algorithm. For this purpose, the error rates at the site of cancerous tissue were determined due to changes in layer thicknesses in layer structures with different acoustic properties.
Green's Functions For A Layered High-Contrast Acoustic Media
(2022) Ozdemir, Ozgur; Yucel, Hazel; Ucar, Yagmur Ece; Erbas, Baris; Ege, Nihal; 35778187
A parametric approach based on parametric analysis of the acoustical properties of a layered media is proposed to derive a reduced layered Green's function. The approach relies on the smallness of one of the problem parameters and allows a simpler form of Green's function by disregarding the smaller parametric terms. Several illustrative examples comparing the amplitudes of exact and reduced Green's function for small parameter of density ratio in various source and observation location setups are presented. It is demonstrated that the CPU times calculated at different points decrease considerably for the reduced Green's function, further justifying the presented method. (C) 2022 Acoustical Society of America.