A modified distorted Born iterative method (DBIM), which includes clustering of reconstructed electrical properties (EPs) after certain iterations, is presented for brain imaging aiming at stroke detection and classification. For this approach to work, a rough estimation number different materials (or bio-tissues) in the imaged domain their corresponding dielectric (permittivity conductivity) are needed as prior information. The proposed adaptive DBIM (AC-DBIM) compared with three...

The accuracy of approximate formulas for the evaluation lightning electromagnetic fields above and inside a lossy ground is investigated taking as reference full-wave numerical results obtained using parallel implementation finite-difference time-domain (FDTD) technique. return stroke channel modeled antenna theory model with fixed inductive loading which appropriately incorporated into FDTD algorithm. First, validity Cooray-Rubinstein (CR) formula above-ground horizontal electric field...

In this paper, we propose an efficient modeling technique for incorporating surge arresters in finite-difference time-domain (FDTD) simulations of lightning-induced disturbances power networks. Instead using piecewise linear approximations the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V–I</i> curve arrester, as usually done literature, derive new updating equations calculation electric field components required at each FDTD time step....

A lens antenna that performs both as a matching medium and spherical-to-planar wave transformer for near-field electromagnetic medical scanning is presented. By achieving those two main targets, the antenna, which can be classified body-matched gradient index (GRIN) lens, maximizes signal penetration forms focused plane incident field distribution inside torso. Consequently, it improves image quality in imaging (EMI) applications. design process proposed based on theory of multilayer with...

Hepatic steatosis is one of the most prevalent chronic liver conditions. Traditional non-invasive imaging modalities are not suitable for observation and treatment evaluation this disease. Hence, study proposes an electromagnetic technique to assist in detection hepatic steatosis. Effective permittivity contrast between left right sides torso exploited aim detection. Firstly, transfer functions transmitter-receiver paths on modeled using a 2D line source approximation form non-linear...

This paper proposes an efficient method for the evaluation of impedance/admittance matrix elements in time-domain integral equation analysis uniformly meshed planar structures. In this method, computation time related to numerical integration required double surface integrals is remarkably reduced by discretizing surfaces equally spaced quadrature points and using spatial translation invariant characteristic Green's function. It shown that computational burden proposed scales as O(N <sub...

Purpose Tall towers have a high potential for being struck by lightning which is major source of electromagnetic radiation with adverse effects on electric, electronic and telecommunication instruments. The paper aims to present an accurate method predicting the radiated fields current distribution along channel tower hit lightning. Design/methodology/approach model utilized represented lossy conducting wires. finite difference time domain (FDTD) used solve governing Maxwell’s equations. Due...

This paper proposes an efficient time-domain method to solve the method-of-moments-formulated integral equation pertinent electromagnetic coupling through aperture into a parallel plate waveguide (PPW) filled with lossy and dispersive dielectric. The proposed utilizes fast Fourier transform-accelerated marching-on-in-time algorithm as solution framework. Appropriate numerical procedures are introduced avoid adverse effects associated frequency-domain windowing aliasing when convolving...

Using a parallel implementation of the finite difference time domain (FDTD) technique, we test accuracy Cooray formula in which underground horizontal electric field is evaluated using its counterpart at air-soil interface. This latter can be calculated either (i) original Cooray-Rubinstein (CR) magnetic ground level assuming as perfect conductor, (ii) taking into account propagation effects computation field. We show that, by fields used CR and for conductivities 0.001 S/m higher, with...