in seismic exploration studies different types of techniques are used to recognize seismic features in terms of their temporal and spatial spectra. variations in frequency content are sensitive to subtle changes in reflection information (castro de matos et al., 2003). in this study the joint time-frequency analysis is used for seismic texture recognition. discrete wavelet transform (dwt) witho...

abstract time domain reflectometry (tdr) is a widely used method for measuring the dielectric constant (ka) and bulk electrical conductivity (σa) in soils. the tdr-measured σa and ka can be used to calculate the soil solution electrical conductivity, (σp). a theoretical model describing a linear relationship between bulk electrical conductivity, σa, and dielectric constant, ka, in moist soil wa...

0

in this paper, an advanced formulation of the spectral finite element method (sfem) is presented and applied in order to carry out site response analysis of 2d topographic structures subjected to vertically propagating incident in-plane waves in time-domain. the accuracy, efficiency and applicability of the formulation are demonstrated by solving some wave scattering examples. a numerical param...

a time-domain approach is presented to calculate electromagnetic fields inside a large electromagnetic pulse (emp) simulator. this type of emp simulator is used for studying the effect of electromagnetic pulses on electrical apparatus in various structures such as vehicles, a reoplanes, etc. the simulator consists of three planar transmission lines. to solve the problem, we first model the meta...

in this work, time domain analysis is used to solve adler’s equation in order to obtain the required time, for an oscillator under external injection, reaching the steady-state condition. mathematical approach has been applied to fully describe the transient of frequency acquisition in injection-locked lc and ring oscillators considering their time-varying nature. then, the analysis is verified...

this paper presents time domain fundamental solutions for the extended biot's dynamic formulations of two-dimensional (2d) unsaturated poroelasticity. unsaturated porous media is considered as a porous media in which the voids are saturated with two immiscible fluids, i.e. liquid and gas. at first, the corresponding explicit laplace transform domain fundamental solution is obtained in term...

in this paper, a new algorithm for studying elastic wave propagation in the phononic crystals is presented. at first, the displacement-based forms of elastic wave equations are derived and then the forms are discretized using finite difference method. so the new algorithm is called the displacement-based finite difference time domain (dbfdtd). three numerical examples are computed with this met...

designing a power splitter with five ports has been shown in this article. in order to prevent the direct coupling between waveguides, a t-shaped structure with an appropriate distance has been used. the coupling between the parallel photonic crystal waveguides is based on multimode interference, while selecting the output efficiency is performed by setting the refractive coefficients and radiu...