Browsing by Subject "Mathematical methods"

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    11th international conference MMET*2006
    (IEEE, 2007) Altıntaş, Ayhan
    The 11th International Conference on Mathematical Methods in Electromagnetic Theory (MMET*06) was organized and sponsored by the IEEE AP-S East Ukraine Joint Chapter at the Kharkiv National University, Kharkiv, Ukraine, june 26-29, 2006. The objective of the conference was to provide an environment for the efficient exchange of research ideas and results, and for the emergence of new friendships and international collaborations across wide range of electromagnetic modeling techniques and applications, as well as to encourage and motivate the young scientists and students in the region.
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    Analysis of an arbitrary profile reflector antenna having resistive-type surface-H-polarization case
    (IEEE, 2008-06-07) Oǧuzer, T.; Altıntaş, Ayhan; Nosich, A. I.
    A regularization-based numerical solution is obtained for arbitrary-shape conic section profile reflector antenna in 2-D, for the H-polarization case. New point is that the reflector surface is assumed a resistive-type material. The problem is treated by reducing the singular integral equation obtained from the boundary condition to the dual series equations and application of the Riemann Hilbert Problem (RHP) technique. The resulting matrix equation has regularized form. Sample numerical results are obtained for various values of the eccentricity of the conic section contour of reflector and the resistivity of its surface. © 2008 IEEE.
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    Numerical modeling of electromagnetic scattering by perfectly conducting surfaces of revolution
    (IEEE, 2008-06-07) Nechitaylo, S.; Sukharevsky, I.; Altıntaş, Ayhan; Sukharevsky, O.
    The integro-differential equation (IDE) of a three-dimensional (3-D) electromagnetic excitation problem of unclosed surfaces is numerically treated by means of the novel direct solver. © 2008 IEEE.
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    Ultraefficient förster-type nonradiative energy transfer enabled by the complex dielectric medium with tuned permittivity
    (American Chemical Society, 2021-06-10) Hernandez-Martinez, P. L.; Yücel, A. C.; Demir, Hilmi Volkan
    Förster-type nonradiative energy transfer (FRET) is one of the primary near-field phenomena and is a useful, fundamental mechanism allowing us to control the excitation energy flow. Using carefully chosen pairs of quantum emitters/absorbers (donors/acceptors), FRET has proved to be essential in a variety of light-generating and -harvesting systems. However, FRET takes place only in a limited spatial range, and its efficiency suffers from an adversely rapidly decreasing profile over the increasing distance between the donor and acceptor. To foster FRET, reaching ultimate levels of efficiency and extending its range, we systematically studied the FRET mechanism by tuning the background medium’s permittivity. The FRET rates of donor–acceptor pairs consisting of a point-like, quasi-0-dimensional quantum dot and quasi-2-dimensional quantum well nanostructures are analytically derived to characterize the change of FRET rates with respect to the medium’s permittivity. The analysis reveals that the FRET rate becomes singular when the permittivity approaches zero and there is a fixed value for the point-like and all other nanostructures, respectively. By setting the medium’s relative permittivity to realistic values near the singular point, which can be realized by a digital metamaterial approach, ultrahigh FRET rates and thereby ultraefficient FRET-based systems are achievable.