scholarly journals An Algorithm for Evaluation of Lightning Electromagnetic Fields at Different Distances with respect to Lightning Channel

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Mahdi Izadi ◽  
Mohd Zainal Abidin Ab Kadir ◽  
Maryam Hajikhani
Keyword(s):  
Electromagnetic Fields ◽  
Time Domain ◽  
Observation Point ◽  
Geometrical Parameters ◽  
Induced Voltage ◽  
Base Current ◽  
Lightning Channel ◽  
The Time Domain

The analytical field expressions are proposed to estimate the electromagnetic fields associated with vertical lightning channel at an observation point directly in the time domain using current and geometrical parameters. The proposed expressions embrace a large number of channel base current functions and widely used engineering current models. Moreover, they can be joined with different coupling models for evaluation of lightning induced voltage when they provide different required field components directly in the time domain. The data from measured fields and simulated fields from previous works were employed to validate the proposed field expressions. The simulated results were compatible with both computed field values from previous studies and the measured fields.

scholarly journals Lightning Channel-Base Current Identification as Solution of a Volterralike Integral Equation

2008 ◽  
Vol 2 (1) ◽  
pp. 160-165 ◽  
Author(s):  
Federico Delfino ◽  
Renato Procopio ◽  
Mansueto Rossi
Keyword(s):  
Integral Equation ◽  
Numerical Simulations ◽  
Time Domain ◽  
Measurement Noise ◽  
Induction Field ◽  
Base Current ◽  
Lightning Channel ◽  
Regularization Techniques ◽  
Ill Conditioning ◽  
The Time Domain

In this paper, a novel procedure to reconstruct the lightning channel-base current starting from the measurement of the induction field generated by it is presented. The procedure is based on a suitable mathematical manipulation of the equation expressing the induction field in the time domain, in order to transform it into a Volterra-like integral equation. Such kind of equations can be easily numerically solved without resorting to any sort of regularization techniques as they are not affected by the typical ill-conditioning of the inverse problems. The developed algorithm has been validated by means of several numerical simulations, which have shown its effectiveness also in presence of measurement noise on the induction field values.

scholarly journals On the Lightning Electromagnetic Fields due to Channel with Variable Return Stroke Velocity

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
M. Izadi ◽  
M. Z. A. Ab Kadir ◽  
M. Hajikhani
Keyword(s):  
Electromagnetic Fields ◽  
Time Domain ◽  
Calculation Methods ◽  
Return Stroke ◽  
Average Value ◽  
Lightning Current ◽  
Lightning Channel ◽  
The Time Domain ◽  
General Velocity ◽  
Good Agreement

Numerical field expressions are proposed to evaluate the electromagnetic fields due to the lightning channel with variable values of return stroke velocity. Previous calculation methods generally use an average value for the return stroke velocity along a lightning channel. The proposed method can support different velocity profiles along a lightning channel in addition to the widely used channel-base current functions and also the general form of the engineering current models directly in the time domain without the need to apply any extra conversions. Moreover, a sample of the measured lightning current is used to validate the proposed method while the velocity profile is simulated by the general velocity function. The simulated fields based on constant and variable values of velocity are compared to the corresponding measured fields. The results show that the simulated fields based on the proposed method are in good agreement with the corresponding measured fields.

Analytical Expressions for Electromagnetic Fields Associated with the Inclined Lightning Channels in the Time Domain

2012 ◽  
Vol 40 (4) ◽  
pp. 414-438 ◽  
Author(s):  
Mahdi Izadi ◽  
Mohd Zainal Ab Kadir ◽  
Chandima Gomes ◽  
Wan Fatin Hamamah Wan Ahmad
Keyword(s):  
Electromagnetic Fields ◽  
Time Domain ◽  
The Time Domain ◽  
Analytical Expressions

On: “Time‐Dependent Electromagnetic Fields of an Infinite, Conducting Cylinder Excited by a Long Current‐Carrying Cable” by S. K. Verma (GEOPHYSICS, April 1973, p. 369–379)

Geophysics ◽  
1974 ◽  
Vol 39 (3) ◽  
pp. 355-355
Author(s):  
Shri Krishna Singh
Keyword(s):  
Magnetic Field ◽  
Frequency Domain ◽  
Electric Current ◽  
Electromagnetic Fields ◽  
Time Domain ◽  
Static Solution ◽  
Transverse Magnetic ◽  
Time Dependent ◽  
Axially Symmetric ◽  
The Time Domain

In this paper Verma obtains a time‐domain solution by inverting the frequency‐domain solution given by Wait (1952). However, it has been recently pointed out by Singh (1973a) (see also Wait, 1973) that there is an error in the quasi‐static solution of Wait. Wait neglected the axially symmetric inducted electric current in the cylinder giving rise to a secondary transverse magnetic field outside (the n=0 term in the scattered wavefield). Singh (1973a) has shown that this term dominates. [It should be noted that Wait in his other works on the cylinder retains this term (e.g., Wait, 1959).] It is clear that this term would be dominant in the time‐domain also. This has been shown by Singh (1972, 1973b). Since the theoretical solution given by Verma in the paper under discussion is incomplete, his interpretation schemes are meaningless.

scholarly journals Electromagnetic fields in linear and nonlinear chiral media: a time-domain analysis

2004 ◽  
Vol 2004 (6) ◽  
pp. 471-486 ◽  
Author(s):  
Ioannis G. Stratis ◽  
Athanasios N. Yannacopoulos
Keyword(s):  
Electromagnetic Fields ◽  
Time Domain ◽  
Linear Time ◽  
Time Domain Analysis ◽  
Local Approximation ◽  
Well Posedness ◽  
Chiral Media ◽  
The Time Domain ◽  
Nonlocal Media ◽  
Nonlocal Medium

We present several recent and novel results on the formulation and the analysis of the equations governing the evolution of electromagnetic fields in chiral media in the time domain. In particular, we present results concerning the well-posedness and the solvability of the problem for linear, time-dependent, and nonlocal media, andresults concerning the validity of the local approximation of the nonlocal medium (optical response approximation). The paper concludes with the study of a class of nonlinear chiral media exhibiting Kerr-like nonlinearities, for which the existence of bright and dark solitary waves is shown.

scholarly journals Considering on Lightning Electric Fields in Presence of Ground Reflection at Non-Perfect Ground

2014 ◽  
Vol 65 (4) ◽  
pp. 242-247
Author(s):  
Mahdi Izadi ◽  
M. Z. A. Ab Kadir ◽  
Maryam Hajikhani
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Time Domain ◽  
General Electric ◽  
Base Current ◽  
Triggered Lightning ◽  
The Time Domain ◽  
Ground Conductivity

Abstract In this paper, general electric field expressions are proposed to consider the effect of channel base ground reflections and ground conductivity on the electric field components due to lightning. The proposed method can support different current models and functions directly in the time domain without the need to apply any extra conversions. The proposed method is applied on a sample of measured channel base current from triggered lightning experiment and the results are discussed accordingly. The results show that the ground reflection and ground conductivity can have an effect on the peak values of the electric fields whereby the electric field components have a great effect on the widely used coupling models.

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