Asian Transactions on Fundamentals of Electronics, Communication & Multimedia

Volume: 02, Issue: 03, July 2012
ISSN 2221-4305

Title: Dual-Frequency Energy Distribution and Computational Analysis for Spectrogram
Author(s): Abdullah Ali Alshehri
Paper ID: ATFECM-70206038
Pages: 1 - 5
Abstract: Time-frequency distributions and their analysis are receiving increased attention in the signal processing research field. Most of the distribution methods that have been proposed do not completely satisfy all distribution properties. Those that satisfy the frequency and time marginals suffer from cross terms or artefacts, while those that are free of cross terms do not satisfy the time and frequency marginals. In this research work, a new distribution will be shown that has a dual-frequency plane instead of the classical time-frequency distribution plane. The dualfrequency distribution is computed from the short-time Fourier transform (STFT) or the spectrogram of the desired signal. The new frequency domain provides spectral information about the old time-frequency kernel but with a high-frequency resolution that improves the frequency marginal property, as seen from the new frequency domain. It compresses the energy spectrum into smaller support regions, unlike the time-frequency spectrum. The details of this new representation will be examined through a simulated multi-component sinusoidal signal to illustrate its frequency-frequency spectrum and its frequency marginals.

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Author(s): Funda Ergün YARDIM, Nursel AKÇAM
Paper ID: ATFECM-30225037
Pages: 6 - 11
Abstract: This paper presents the analysis of the reflection error of anisotropic perfectly matched layer (UPML) using two dimensional Finite Difference Time Domain (FDTD) method. UPML method is introduced briefly and then the difference equations and parameters are defined using central difference approximations. The explicit update equations of the electromagnetic fields are obtained. Numerical examples show that the UPML leads to very small reflection error for TEz and TMz polarized waves.

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Title: The Chromatic Field Aberration of Monopole, Dipole and Quadrupole Magnetic Lenses
Author(s): Bahaa A.H. Jawad, Ayad A. Al-Ani, and Oday A. Hussien
Paper ID: ATFECM-10233037
Pages: 12 - 17
Abstract: The chromatic field aberration of magnetic lenses with field distribution in the form of inverse law has been theoretically studied by using analytical method. Analytical expressions for magnification and rotation chromatic aberration coefficients, for all magnetic lenses at the focus, are given. The results of calculations show that the increasing in the order of multipole “n” leads to increasing the magnification chromatic aberration coefficient although the rotation chromatic aberration coefficient is slightly decreasing.

Full Text: PDF (530 KB)