Yazar "Yelkenci, Tanju" seçeneğine göre listele

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    A mathematical computer model for estimating phase weight/ atomic fractions for iron slags’ system (SiO2-Al203-CaO-MgO) at subsolidus temperatures
    (Springer, 2023) Yelkenci, Tanju; Erkmen, Z. Engin
    In this study, the 3 dimensional description of the quaternary subsolidus slag system aluminasilicacalciamagnesia is evaluated using Mathematica programming based on previous experimental research data. The lever rule in the tetrahedra is then applied for a given arbitrary liquid composition %A ? %B ? %C ? %D = 100 in order to calculate the solid phases present (neglecting solid solutions) with their relative proportions after the solidification is completed. A novel transformation and algorithm are then developed using simple geometry and Matlab programming which can also be used for other subsolidus systems in case appropriate data are provided.
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    A Mathematical Computer Model for Estimating Phase Weight/Atomic Fractions for Iron Slags' System (SiO2-Al203-CaO-MgO) at Subsolidus Temperatures
    (Springer, 2023) Yelkenci, Tanju; Erkmen, Z. Engin
    In this study, the 3 dimensional description of the quaternary subsolidus slag system aluminasilicacalcia-magnesia is evaluated using Mathematica programming based on previous experimental research data. The lever rule in the tetrahedra is then applied for a given arbitrary liquid composition A% + %B + %C + %D = 100 in order to calculate the solid phases present (neglecting solid solutions) with their relative proportions after the solidification is completed. A novel transformation and algorithm are then developed using simple geometry and MathLab programming which can also be used for other subsolidus systems in case appropriate data are provided.
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    Analysis of the Matching Media Effects by Microwave Field Distribution Simulations for the Cylindrically Layered Human Arm Model
    (Mdpi, 2025) Yelkenci, Tanju
    In this study, a method is presented to determine the matching media parameters that maximize the electromagnetic energy penetrating into the human arm modeled as a radially stratified cylinder. In this context, first, the electromagnetic scattering problem related to the layered cylindrical model in question was solved analytically using cylindrical harmonics. Then, based on this solution, a frequency-dependent functional in terms of the electromagnetic parameters of the matching medium was defined, and the parameters that minimize this functional were determined through the graphs of this functional. In this functional, which depends on the permittivity, conductivity and frequency of the matching medium, one parameter was kept constant at every turn while the other two parameters were optimized. The accuracy of the approach was demonstrated by calculating the electric field amplitudes inside and outside the layers for the parameters determined by the proposed method. The numerical results given in this context demonstrate that if a matching medium is used, the penetrating field increases between 1.3 to 13.96 times compared to the case where the matching medium is absent.
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    Determination of the Dielectric Coating Parameters to Reduce the Radar Cross-section of the Perfectly Conducting Cylinder
    (Institute of Electrical and Electronics Engineers Inc., 2023) Yelkenci, Tanju
    By defining a functional, a parametric analysis of the dielectric coated infinitely long perfect electromagnetic conducting (PEC) cylinder at a fixed frequency is carried out in order to reduce the radar cross section (RCS) over a range of thickness and permittivity of the layer. The RCS of the cylindrical structure is determined analytically where the fields in different regions are expressed in terms of infinite series summation of Bessel and Hankel functions when a TM polarized plane wave is incident. A comparison of the simulation results with those of the bistatic RCS far- field approximation demonstrates very good agreement. © 2023 IEEE.
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    Dielektrik Kaplı İletken Silindirden Saçılan Alanın Minimizasyonu
    (Dokuz Eylül Üniversitesi, 2024) Yelkenci, Tanju
    Bu çalışmada, TM polarize düzlem dalga ile aydınlatılan, dielektrik malzeme ile kaplı sonsuz uzun, mükemmel iletken, dairesel bir silindirin RKA (radar kesit alanı)’ nı en aza indirmek için analitik yönteme dayalı bir analiz önerilmektedir. Silindirik yapıdan saçılan alan, farklı bölgelerde Bessel ve Hankel fonksiyonlarının sonsuz seri toplamı cinsinden ifade edilerek analitik olarak belirlenmiştir. Burada temel yaklaşım olarak kalınlık veya permitivite veya frekansın sabit olduğu varsayılarak, iki değişken parametreye bağımlı bir fonksiyonelin parametrik analizi yapılmış ve yapının RKA’nı en aza indirgeyen parametreler belirlenmiştir. Elde edilen sonuçların tutarlılığı, uzak alan ifadeleri gözlemlenerek gösterilmiş ve önerilen yöntemin başarısı çeşitli durumlar için tartışılmıştır.
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    Imaging of cylindrical inhomogeneites in a parallel plate waveguide with reverse time migration method
    (Walter De Gruyter Gmbh, 2024) Yelkenci, Tanju
    While reverse time migration (RTM) algorithm is commonly used in geophysical explorations, this paper addresses the RTM imaging procedure for reconstructing of lossy dielectric discontinuities in a planar waveguide using electromagnetic waves at a single frequency. The direct problem of the related configuration is solved via method of moments (MoM) to produce the synthetic scattered data to be used in RTM. The achievements of the method are examined and verified by including different numerical examples. It is shown that the RTM approach can be used as an alternative imaging methodology in parallel plate waveguide problems.
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    Imaging of Rough Surfaces by RTM Method
    (Ieee-Inst Electrical Electronics Engineers Inc, 2024) Sefer, Ahmet; Yapar, Ali; Yelkenci, Tanju
    An electromagnetic (EM) imaging framework is implemented utilizing a single-frequency reverse time migration (RTM) technique to accurately reconstruct inaccessible 2-D rough surface profiles from the knowledge of scattered field data. The unknown surface profile, which is expressed as a 1-D height function, is either perfectly electric conducting (PEC) or an interface between two penetrable media. For both cases, it is assumed that the surface is illuminated by a number of line sources located in the upper medium. The scattered fields, which should be collected by real measurements in practical applications, are obtained synthetically by solving the associated direct scattering problem through the surface integral equations. RTM is subsequently applied to generate a cross correlation imaging function which is evaluated numerically and provides a 2-D image of the region of interest. A high correlation is observed by the function in the regions where the transitions between two media occur. Hence, it results in the acquisition of the unknown surface profile at the sites where the function attains its highest values. The efficiency of the proposed method is comprehensively tested by numerical examples covering various types of scattering scenarios.