Effects of Lightning Current and Ground Conductivity on the Values of Vertical Electric Fields

2013 ◽  
Vol 64 (4) ◽  
Author(s):  
M. Izadi ◽  
M. Z. A. Ab Kadir ◽  
M. Hajikhani ◽  
N. Rameli
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Lightning Current ◽  
Lightning Channel ◽  
Vertical Electric Field ◽  
The Relationship ◽  
Ground Conductivity

In this paper, the relationship between current front time and front time of vertical electric field due to lightning channel at non perfect ground is considered. Results showed that the peak of simulated vertical electric fields under non perfect ground conductivity condition is decreased compared to the corresponding field at perfect ground while the front time of field is increased at non perfect case compared to the perfect one. Likewise, the effect of ground conductivity on the peak and front time of simulated vertical electric field is considered and the results are discussed accordingly.

The Effect of Direct Lightning Shielding Rod on Lightning Electromagnetic Fields Aboveground

Frequenz ◽  
2017 ◽  
Vol 71 (5-6) ◽  
Author(s):  
Ya-Peng Fu ◽  
Cheng Gao ◽  
Bo Yang
Keyword(s):  
Electric Field ◽  
Electromagnetic Fields ◽  
Fdtd Method ◽  
Shielding Effect ◽  
Azimuthal Magnetic Field ◽  
Lightning Channel ◽  
Vertical Electric Field ◽  
New Type ◽  
Difference Time ◽  
Ground Conductivity

AbstractA practical new type direct lightning shielding rod is designed to reduce the electromagnetic radiation produced by lightning stroking to Franklin lightning rod in the paper. The Finite-Difference Time-Domain (FDTD) method is adopted for analyzing. It is the shielding layer that affects the electromagnetic fields and the insulating medium make no difference. All the electromagnetic fields amplitude obtained decrease for the shielding layer existing, regardless of any condition, but the extent is different. That is, the effect on the horizontal electric field is most noticeable, the vertical electric field comes second, minimum the azimuthal magnetic field. All the field components are affected by shielding layer height and the distance between shielding layer and lightning channel, but not significantly by the shielding layer grounding depth. The shielding effect is more obvious with lower ground conductivity, but the ground relative permittivity makes no difference.

Electric Field Effects on the Stability of Vapor Microlayers: Enhancement of Heat Transfer

Materials ◽  
2003 ◽  
Author(s):  
Subramanian Sankaran ◽  
Jeffrey S. Allen ◽  
Leonard Gumennik
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Heat Fluxes ◽  
Enhancement Of Heat Transfer ◽  
Electric Field Effects ◽  
Heater Wire ◽  
Experimental Parameters ◽  
Flux Level ◽  
The Stability ◽  
The Relationship

The effect of dc electric fields on destabilization of a vapor microlayer formed during film boiling at various subcooling levels is investigated. High voltage electric fields up to 2000 volts were applied between a 127 μm heater wire and a screen electrode that is concentrically placed at a radius of 25 mm. The qmax and qmin heat fluxes were also measured for the various subcooling and electric field strengths. Up to 50% increase in the qmax and the qmin heat fluxes were observed when using the electric fields in this range of experimental parameters. The relationship among subcooling level for a given fluid, the heat flux level, and the electric field strength required to reach the qmin condition is of interest. The preliminary experimental results and the bubble departure and transition boiling patterns resulting from destabilization of the vapor microlayer are discussed.

Investigation of Retention Properties for YMnO3 Based Metal/Ferroelectric/Insulator/Semiconductor Capacitors

2003 ◽  
Vol 784 ◽  
Author(s):  
T. Yoshimura ◽  
D. Ito ◽  
H. Sakata ◽  
N. Shigemitsu ◽  
K. Haratake ◽  
...  
Keyword(s):  
Electric Field ◽  
Leakage Current ◽  
Electric Fields ◽  
Retention Time ◽  
Memory Retention ◽  
Frenkel Emission ◽  
Transient Spectroscopy ◽  
Leakage Current Mechanism ◽  
Capacitance Transient ◽  
The Relationship

ABSTRACTThe memory retention properties of Pt/YMnO3/Y2O3/Si capacitors were investigated for the application of ferroelectric gate transistors. The epitaxially grown Pt/YMnO3/Y2O3/Si capacitors showed ferroelectric type hysteresis loop on the capacitance-voltage properties. Although the retention time of the as-deposited capacitors was ∼103 s, it was prolonged up to 104 s when the leakage current density was reduced from 4×10-8 A/cm2 to 2×10-9 A/cm2 by the annealing under N2 ambience. To reveal the relationship between the retention time and leakage current, the leakage current mechanism was investigated comparing several conduction mechanisms. It was found that the dominant leakage mechanisms at high and low electric fields were Poole-Frenkel emission from the Y2O3 layer and ohmic conduction, respectively. This result indicates that the leakage current was limited by the Y2O3 layer at high electric field and was mainly dominated by the amount of defects in the YMnO3 layer at low electric field. From the pseudo isothermal capacitance transient spectroscopy (ICTS), it was determined that the trap density was in an order of 1015 cm-3. Since the variation of the leakage current by annealing was observed only in the low electric field region, it is suggested that the retention properties of the Pt/YMnO3/Y2O3/Si capacitors was influenced by the amount of defects in the YMnO3 layer.

scholarly journals Seafloor massive sulphide exploration using deep-towed controlled source electromagnetics: Navigational uncertainties

2019 ◽  
Author(s):  
Romina A S Gehrmann ◽  
Amir Haroon ◽  
McKinley Morton ◽  
Axel T Djanni ◽  
Timothy A Minshull
Keyword(s):  
Electric Field ◽  
Error Estimation ◽  
Electric Fields ◽  
Final Model ◽  
Controlled Source ◽  
Precise Knowledge ◽  
Geophysical Surveys ◽  
Vertical Electric Field ◽  
Irregular Motion ◽  
Data Error

SUMMARY Deep-towed geophysical surveys require precise knowledge of navigational parameters such as instrument position and orientation because navigational uncertainties reflect in the data and therefore in the inferred geophysical properties of the sub-seafloor. We address this issue for the case of electrical conductivity inferred from controlled source electromagnetic data. We show that the data error is laterally variable due to irregular motion during deep towing, but also due to lateral variations in conductivity, including those resulting from topography. To address this variability and quantify the data error prior to inversion, we propose a two-dimensional perturbation study. Our workflow enables stable and geologically reliable results for multi-component and multi-frequency inversions. An error estimation workflow is presented, which comprises the assessment of navigational uncertainties, perturbation of navigational parameters, and forward modelling of electric field amplitudes for a homogeneous and then a heterogeneous sub-seafloor conductivity model. Some navigational uncertainties are estimated from variations of direct measurements. Other navigational parameters required for inversion are derived from the measured quantities and their error is calculated by means of error propagation. Some navigational parameters show direct correlation with the measured electric fields. For example, the antenna dip correlates with the vertical electric field and the depth correlates with the horizontal electric field. For the perturbation study each standard deviation is added to the navigational parameters. Forward models are run for each perturbation. Amplitude deviations are summed in quadrature with the stacking error for a total, laterally varying, data error. The error estimation is repeated for a heterogeneous sub-seafloor model due to the large conductivity range (several orders of magnitude), which affects the forward model. The approach enables us to utilize data from several components (multiple electric fields, frequencies and receivers) in the inversion to constrain the final model and reduce ambiguity. The final model is geologically reasonable, in this case enabling the identification of conductive metal sulphide deposits on the seafloor.

scholarly journals Computation of Lightning Current from Electric Field Based on Laplace Transform and Deconvolution Method

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4201
Author(s):  
Grzegorz Karnas
Keyword(s):  
Transfer Function ◽  
Electric Field ◽  
Laplace Transform ◽  
Vertical Component ◽  
Lightning Strike ◽  
Function Estimation ◽  
Base Current ◽  
Lightning Current ◽  
Lightning Channel ◽  
Lightning Impulse

A method for computation of the lightning channel base current from the corresponding vertical component of lightning electric field was presented. The algorithm was developed by applying Laplace transform. The lightning current was estimated from its deconvolution with a special transfer function. The transfer function includes information about geometry and physical properties of entire lightning impulse generation system. The method was verified for a Heidler-type base current and a MTLL model of its propagation within the lightning channel. Research was done for close, middle, and far distance to the lightning strike point. Optimum performance was obtained for the middle distance of several kilometers where the electrostatic, induction, and radiation components of the transfer function were of the same range. An analysis was done for input electric field with and without noise superimposed on its time domain waveform. Relative uncertainties for the electric field and calculated lightning channel base current were similar each other. The presented approach can substantially increase a number of lightning current parameters which can be identified on the basis of its electric field signature. This method can be applied by the lightning location systems using preprocessing which increases the timing efficiency of the transfer function estimation.

Investigation of Retention Properties for YMnO3 Based Metal/Ferroelectric/Insulator/Semiconductor Capacitors

2003 ◽  
Vol 786 ◽  
Author(s):  
T. Yoshimura ◽  
D. Ito ◽  
H. Sakata ◽  
N. Shigemitsu ◽  
K. Haratake ◽  
...  
Keyword(s):  
Electric Field ◽  
Leakage Current ◽  
Electric Fields ◽  
Retention Time ◽  
Memory Retention ◽  
Frenkel Emission ◽  
Transient Spectroscopy ◽  
Leakage Current Mechanism ◽  
Capacitance Transient ◽  
The Relationship

ABSTRACTThe memory retention properties of Pt/YMnO3/Y2O3/Si capacitors were investigated for the application of ferroelectric gate transistors. The epitaxially grown Pt/YMnO3/Y2O3/Si capacitors showed ferroelectric type hysteresis loop on the capacitance-voltage properties. Although the retention time of the as-deposited capacitors was ∼103 s, it was prolonged up to 104 s when the leakage current density was reduced from 4×10−8 A/cm2 to 2×10−9 A/cm2 by the annealing under N2 ambience. To reveal the relationship between the retention time and leakage current, the leakage current mechanism was investigated comparing several conduction mechanisms. It was found that the dominant leakage mechanisms at high and low electric fields were Poole-Frenkel emission from the Y2O3 layer and ohmic conduction, respectively. This result indicates that the leakage current was limited by the Y2O3 layer at high electric field and was mainly dominated by the amount of defects in the YMnO3 layer at low electric field. From the pseudo isothermal capacitance transient spectroscopy (ICTS), it was determined that the trap density was in an order of 1015 cm−3. Since the variation of the leakage current by annealing was observed only in the low electric field region, it is suggested that the retention properties of the Pt/YMnO3/Y2O3/Si capacitors was influenced by the amount of defects in the YMnO3 layer.

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.

Electrical Tomography Sensing and Dielectrophoresis in Microchannel for 3D Particle Mixing

2011 ◽  
Author(s):  
Nur Tantiyani Ali Othman ◽  
Je-Eun Choi ◽  
Masahiro Takei
Keyword(s):  
Electric Field ◽  
Cross Section ◽  
Electric Fields ◽  
Cross Sections ◽  
Electrical Tomography ◽  
Field Frequency ◽  
Particle Mixing ◽  
Measurement Plane ◽  
Electric Field Frequency ◽  
The Relationship

The present study describes the electrical tomography sensing and dielectrophoresis (DEP) force for visualize the 3D particle mixing in the microchannel system. In the presence of non-uniform electric fields generated by point microelectrodes, the dynamic distribution behaviors of a polystyrene particle and deionized water had been investigated in this system. Microchannel was fabricated with five cross sections where 12 electrodes were installed for each measurement plane. In this experiment, the relationship between electric field frequency and DEP force of particles are calculated at different electric frequencies and diameter of particles. The applied electric field intensities are E = ±1 V/mm, ±3 V/mm and ±5 V/mm while the electric field frequencies are f = 1 kHz, 10 kHz, 100 kHz and 1 MHz and the diameter of particles are 1.3μm, 1.5μm and 2.0μm are investigated in this experiment. Simultaneously, imaged by manipulating tomography sensing at cross section A, C and D and the coupled DEP forces at cross section B and D, the particles flowing had been visualized and concentrate uniformly at near the outlets. The electrical capacitances and DEP forces between the electrode pairs of the microchannel were measured and the ECT tomograms representing the particle distribution were constructed from the measured capacitance data for each cross section in microchannel.

Formaldehyde diffusion within crystalline and amorphous cellulose at different temperatures and electric fields: A molecular dynamics study

2017 ◽  
Vol 28 (2) ◽  
pp. 175-185 ◽  
Author(s):  
Bo Xu ◽  
Zhenqian Chen
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Coefficient ◽  
Molecular Dynamics Simulation ◽  
Electric Field ◽  
Electric Fields ◽  
Amorphous Region ◽  
Dynamics Simulation ◽  
Amorphous Cellulose ◽  
Different Temperatures ◽  
The Relationship

To provide a microcosmic theoretical support for the reduction of formaldehyde in building material, the diffusion process was investigated by molecular dynamics simulation. In addition, the diffusion model of formaldehyde molecules in crystalline and amorphous cellulose was built, and diffusion coefficients at different temperatures and electric fields were studied. The simulation temperature was from 293 to 393 K and electric field was from 0 to 400 kV/m. Diffusion coefficient increased with greater temperature and electric field both in crystalline and amorphous region. However, the diffusion coefficient in amorphous region could be ignored for it was two orders of magnitude lower than diffusion coefficient in crystalline region. The relationship between diffusion coefficient and temperature, and the relationship between diffusion coefficient and electric field were obtained by simulation, verified by the experiment. Temperature was shown to have a significant contribution to formaldehyde diffusion than electric field. Compared with experimental studies, the molecular dynamics simulation could only analyse the diffusion coefficient qualitatively because of the difference between micro-scale and macro-scale.

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