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.

scholarly journals Comparison of lightning return stroke channel-base current models with measured lightning current

2019 ◽  
Vol 8 (4) ◽  
Author(s):  
Chin-Leong Wooi ◽  
Zulkurnain Abul-Malek ◽  
Mohamad Nur Khairul Hafizi Rohani ◽  
Ahmad Muhyiddin Bin Yusof ◽  
Syahrun Nizam Md Arshad ◽  
...  
Keyword(s):  
Full Width Half Maximum ◽  
Electronic Systems ◽  
Stroke Model ◽  
Lightning Stroke ◽  
Return Stroke ◽  
Current Function ◽  
Base Current ◽  
Lightning Current ◽  
Lightning Channel ◽  
Good Agreement

Electromagnetic pulse radiation produced around the lightning stroke channel has caused the disturbance to the microelectronic industry, especially to disturbance of high frequency to electronic systems. Lightning channel-base current function (CBC) characteristics and parameters determine lightning electromagnetic field (LEMF) results obtained on the basis of the used models. This paper evaluated and compared the measured lightning current and six lightning current-based channels models namely Bruce and Golde, Heidler, Diendorfer and Uman, Nucci, Pierce and Cianos and new current-based current (NCBC) models. In terms of the waveshape, among all the six lightning channel-based current models discussed, the models developed by Javor, Nucci and Diendorfer and Uman have showed a good agreement compared to the measured lightning current. In terms of 10-90% risetime and full width half maximum time (FWHM) comparison, NCBC and Nucci models have showed compatible comparison. However, Nucci model is not easily adjustable to different desired pulse-current waveshapes. On the other hand, NCBC model can be simplified, the values of lightning peak current and risetime can be chosen arbitrarily and independently from other parameters, and there is no need for the peak-correction factor, so that reduces the number of parameters. Therefore, the NCBC model was suggested to be used in the future in order to simulate much accurate return stroke model. This knowledge will contribute to the development of a new accurate and efficient return stroke model.

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.

High Amplitude Sound Propagation at Low Frequencies in a Flow Duct Lined With Resonators: A Time Domain Solution

1988 ◽  
Vol 110 (4) ◽  
pp. 545-551 ◽  
Author(s):  
A. Cummings ◽  
I.-J. Chang
Keyword(s):  
Time Domain ◽  
Internal Combustion Engines ◽  
Sound Propagation ◽  
Sound Field ◽  
High Amplitude ◽  
Combustion Engines ◽  
Low Frequencies ◽  
The Time Domain ◽  
Flow Duct ◽  
Good Agreement

A quasi one-dimensional analysis of sound transmission in a flow duct lined with an array of nonlinear resonators is described. The solution to the equations describing the sound field and the hydrodynamic flow in the neighborhood of the resonator orifices is performed numerically in the time domain, with the object of properly accounting for the nonlinear interaction between the acoustic field and the resonators. Experimental data are compared to numerical computations in the time domain and generally very good agreement is noted. The method described here may readily be extended for use in the design of exhaust mufflers for internal combustion engines.

Analysis of the DLR Planetary Roller Spindle Drive

1998 ◽  
Author(s):  
Matthias Balázs ◽  
Martin Spieck
Keyword(s):  
Time Domain ◽  
Multibody System ◽  
Dynamical Behaviour ◽  
Calculation Methods ◽  
Operating Characteristics ◽  
Modelling Analysis ◽  
Linear Movement ◽  
And Performance ◽  
The Time Domain ◽  
German Aerospace

Abstract The DLR Planetary Roller Spindle Drive (PRSD), a new linear actuator developed at the German Aerospace Center (DLR), transforms fast rotation of a drive into slow but powerful linear movement. To optimize dynamical behaviour and performance of modified PRSD design versions, modelling and calculation methods have been developed, taking into account the very special requirements of this new design. To analyze the operating characteristics and performance figures, the DLR Planetary Roller Spindle Drive was modelled as a multibody system (MBS). Special attention was directed on the description of the complex contact mechanics between the PRSD elements. Accompanying experiments ensured the accuracy of the modelling. Analysis of the MBS model of an existing PRSD in the time domain showed satisfying accordance with testbench measurements.

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.

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

Research on the Static and Dynamics Characteristics of Soft Yoke Mooring System Based on Multi-Rigid Body Interaction

2020 ◽  
Author(s):  
Hongwei Wang ◽  
Zizhao Zhang ◽  
Gang Ma ◽  
Rongtai Ma ◽  
Jie Yang
Keyword(s):  
Time Domain ◽  
Rigid Bodies ◽  
Coupled Analysis ◽  
Mooring System ◽  
Accurate Analysis ◽  
Restoring Force ◽  
Stiffness Characteristics ◽  
The Time Domain ◽  
Multi Body ◽  
Good Agreement

Abstract Select the common mooring system-soft yoke mooring system as the research object. The soft yoke mooring system is regarded as a structure composed of multiple rigid bodies, and the theoretical analysis of multi-body dynamics is used to discuss the interaction of multi-rigid bodies. The classical HYSY113 FPSO is selected as an example, for the soft yoke mooring system, the stiffness characteristics and static restoring force curved compared with those of software OrcaFlex, and they are in good agreement, which verify the reliability of the formula derived, and it is a prerequisite for the accurate simulations in further steps. Coupled analysis to the whole system in time domain is also carried out both in OrcaFlex and AQWA, and the representative response of the FPSO under different environmental conditions is compared, the results are consistent well with each other. It is a good reference for the future study in this field. Good static characteristics are a prerequisite for accurate analysis of time-domain motion. By comparing the results in the time domain, it is found that under the same working conditions, the analysis results calculated by different commercial software (AQWA and OrcaFlex) may be different. We need to perform design analysis based on the characteristics of the software.

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.

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