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.

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.

Current and radiated electromagnetic fields due to lightning return strokes when hitting elevated objects

2016 ◽  
Vol 35 (3) ◽  
Author(s):  
Maryam Hajebi ◽  
Mojtaba Khosravi-Farsani ◽  
Seyed Hossein Hesamedin Sadeghi ◽  
Rouzbeh Mazandarani Moini
Keyword(s):  
Electromagnetic Fields ◽  
Current Distribution ◽  
Design Methodology ◽  
Fdtd Method ◽  
Measurement Data ◽  
Vertical Component ◽  
Uniform Mesh ◽  
Large Space ◽  
Lightning Channel ◽  
The Impact

Purpose Tall towers have a high potential for being struck by lightning which is a major source of electromagnetic radiation with adverse effects on electric, electronic and telecommunication instruments. The paper aims to present an accurate method for predicting the radiated electromagnetic fields and current distribution along the lightning channel and the tower hit by the lightning. Design/methodology/approach The electromagnetic model is utilized to model the lightning channel and the tower is represented by lossy conducting wires. The finite difference time domain (FDTD) method is used to solve for the governing Maxwell’s equations. Due to the large computational space, the FDTD code is paralleled between several computer processors. To enhance the efficiency of the code, a non-uniform mesh is used, reducing the mesh length in the air-ground interface. For model evaluation, simulated current distribution along the lightning channel and tower, and the radiated electromagnetic fields are compared with the measurement data and those obtained using the engineering models. Findings The proposed modeling technique has proved to be more accurate than the conventional methods, particularly in the prediction of current distribution along the tall tower and the vertical component of the radiated electric field. Originality/value The main feature of the proposed technique is its ability to consider the impact of metallic structures in a large space around lightning channel on the predicted radiated electromagnetic fields, having no concern on computer memory requirements.

Two Dimensional Photonic Filter with a Circular Resonant Cavity

2013 ◽  
Vol 712-715 ◽  
pp. 1751-1754
Author(s):  
Zhao Xia Wu ◽  
Yuan Long Shao ◽  
Wen Chao Li ◽  
Er Dan Gu
Keyword(s):  
Dielectric Constant ◽  
Resonant Cavity ◽  
Fdtd Method ◽  
Circular Ring ◽  
Two Dimensional ◽  
Transmission Characteristics ◽  
New Type ◽  
Micro Cavity ◽  
The Impact ◽  
Difference Time

A new type of the two dimensional photonic filter which includes two in-line waveguides and a circular ring resonant cavity is presented in this paper. By using Finite Difference Time Domain (FDTD) method, we calculated and demonstrated the broadband frequency response of the filter and analyzed the impact of changing the dielectric constant of the inner rods on the transmission characteristics of the filter. Compared with the transmission characteristics of a micro-cavity,our numerical results show that such a filter can transmit multiple narrowband signals simultaneously. The number of the passbands of the filter increases with the rings of inner dielectric rods in the cavity. The center wavelength of the passbands can be tuned by adjusting the dielectric constant of the whole rods and inner rods without changing the size of the cavity..

scholarly journals Wave Propagation in a Fractional Viscoelastic Tissue Model: Application to Transluminal Procedures

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2778
Author(s):  
Antonio Gomez ◽  
Guillermo Rus ◽  
Nader Saffari
Keyword(s):  
Wave Propagation ◽  
Soft Tissue ◽  
Imaging Modality ◽  
Shear Waves ◽  
Fdtd Method ◽  
Propagation Model ◽  
Rheological Models ◽  
New Type ◽  
Difference Time ◽  
Wave Propagation Model

In this article, a wave propagation model is presented as the first step in the development of a new type of transluminal procedure for performing elastography. Elastography is a medical imaging modality for mapping the elastic properties of soft tissue. The wave propagation model is based on a Kelvin Voigt Fractional Derivative (KVFD) viscoelastic wave equation, and is numerically solved using a Finite Difference Time Domain (FDTD) method. Fractional rheological models, such as the KVFD, are particularly well suited to model the viscoelastic response of soft tissue in elastography. The transluminal procedure is based on the transmission and detection of shear waves through the luminal wall. Shear waves travelling through the tissue are perturbed after encountering areas of altered elasticity. These perturbations carry information of medical interest that can be extracted by solving the inverse problem. Scattering from prostate tumours is used as an example application to test the model. In silico results demonstrate that shear waves are satisfactorily transmitted through the luminal wall and that echoes, coming from reflected energy at the edges of an area of altered elasticity, which are feasibly detectable by using the transluminal approach. The model here presented provides a useful tool to establish the feasibility of transluminal procedures based on wave propagation and its interaction with the mechanical properties of the tissue outside the lumen.

FDTD Modelling of Triangular Gold Nanoparticle Pairs

2014 ◽  
Vol 703 ◽  
pp. 220-223
Author(s):  
Yang Fan
Keyword(s):  
Electric Field ◽  
Gold Nanoparticle ◽  
Time Domain ◽  
Finite Difference Time Domain ◽  
Fdtd Method ◽  
Field Enhancement ◽  
Electric Field Enhancement ◽  
Plasmon Resonances ◽  
Simulation Results ◽  
Difference Time

The optical properties of triangular gold nanoparticle pairs are investigated by numerical simulations using Finite-difference time-domain (FDTD) method. The simulation results show the significant red shifts of plasmon resonances as the size of nanoparticle is increased. The large electric field enhancement is also verified by calculating the local electric field distributions.

An Algorithm of 3-D ADI-R-FDTD Based on Non-Zero Divergence Relationship

2011 ◽  
Vol 317-319 ◽  
pp. 1172-1176
Author(s):  
Xiu Hai Jin ◽  
Yi Wang Chen ◽  
Pin Zhang
Keyword(s):  
Magnetic Field ◽  
Finite Difference ◽  
Electric Field ◽  
Time Domain ◽  
Finite Difference Time Domain ◽  
Fdtd Method ◽  
Memory Requirement ◽  
Alternating Direction ◽  
Relationship Of ◽  
Difference Time

In this letter, an alternating-direction reduced finite-difference time-domain (ADI-R-FDTD) method is presents. It is proven that the divergence relationship of electric-field and magnetic-field is non-zero even in charge-free regions, when the electric-field and magnetic-field are calculated with alternating-direction finite-difference time-domain (ADI-FDTD) method in 3 dimensions case, and the expression of the divergence relationship is derived. Based on the non-zero divergence relationship, the ADI-FDTD method is combined with the reduced finite-difference time-domain (R-FDTD) method. In the proposed method, the memory requirement of ADI-R-FDTD is reduced by1/12 of the memory requirement of ADI-FDTD averagely in 3D case. The formulation is presented and the accuracy and efficiency of the proposed method is verified by comparing the results with the conventional results.

Anisotropic refraction and valley-spin-dependent anomalous Klein tunneling in an 1T′-MoS2-based p-n junction

2021 ◽  
Author(s):  
Fenghua Qi ◽  
Xingfei Zhou
Keyword(s):  
Electron Beam ◽  
Band Structure ◽  
Electric Field ◽  
Transport Properties ◽  
Incident Angle ◽  
External Fields ◽  
Valley Splitting ◽  
Klein Tunneling ◽  
Vertical Electric Field ◽  
New Type

Abstract We investigate the transport properties of electron in an 1T′-MoS2-based p-n junction. The anisotropic refraction of electron is found when the electron beam crosses the p-n junction, which brings the phenomenon of valley splitting without any external fields. Besides, the valley-spin-dependent anomalous Klein tunneling, i.e., the perfect transmission exists at a nonzero incident angle of valley-spin-dependent electron, happens when the vertical electric field is equal to the critical electric field. These two peculiar properties arise from the same reason that the tilted band structure makes the directions of wavevector and velocity different. Our work designs a special valley splitter without any external fields and finds a new type of Klein tunneling.

scholarly journals Implementation of an analytical formulation for LEMP to assess the lightning performance of a distribution line

TecnoLógicas ◽  
2018 ◽  
Vol 21 (42) ◽  
pp. 51-62 ◽  
Author(s):  
Edison Soto ◽  
Ernesto Pérez
Keyword(s):  
Electric Field ◽  
Analytical Formula ◽  
Computation Time ◽  
Finite Conductivity ◽  
Wave Shape ◽  
Azimuthal Magnetic Field ◽  
Analytical Formulation ◽  
Vertical Electric Field ◽  
Distribution Line ◽  
Time Required

This paper presents the implementation of an analytical formulation to calculate the lightning electromagnetic pulse (LEMP) assuming a current wave-shape linearly rising with flat top and a transmission Line (TL) return-stroke model. It also describes the development of the expressions for the image dipoles required to calculate the vertical electric field, the azimuthal magnetic field and, specially, the horizontal electric field. The expressions to calculate the contribution of source dipoles were detailed in a previous publication by other authors. The complete formulation is used to calculate electromagnetic fields and lightning-induced voltages on a typical overhead distribution line. The results were compared with traditional formulas to calculate the LEMP (such as Rubinstein’s) and to calculate induced voltages (such as Rusck’s) showing errors below 1%. If a more complex wave shape was used (such as Heidler’s), errors below 5% were found. Additionally, the formula was employed to calculate the flashover rate of a distribution line above a ground with infinite and finite conductivity. Errors less than 5% were found compared to the results obtained in the IEEE 1410 Standard. On the other hand, the computation time required to the assessment of an overhead line indirect lightning performance is reduced by half when the analytical formula is used.

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