scholarly journals A new lightning return stroke model based on antenna theory

2000 ◽  
Vol 105 (D24) ◽  
pp. 29693-29702 ◽  
Author(s):  
Rouzbeh Moini ◽  
Behzad Kordi ◽  
Gholamreza Z. Rafi ◽  
Vladimir A. Rakov
Keyword(s):  
Stroke Model ◽  
Return Stroke ◽  
Antenna Theory ◽  
Model Based

Stroke-model-based character extraction from gray-level document images

2001 ◽  
Vol 10 (8) ◽  
pp. 1152-1161 ◽  
Author(s):  
Xiangyun Ye ◽  
M. Cheriet ◽  
C.Y. Suen
Keyword(s):  
Gray Level ◽  
Document Images ◽  
Stroke Model ◽  
Model Based ◽  
Character Extraction

scholarly journals Modeling of the Stepping Process of Negative Lightning Stepped Leaders

2017 ◽  
Author(s):  
Vernon Cooray ◽  
Liliana Arevalo
Keyword(s):  
Physical Model ◽  
Reasonable Agreement ◽  
Propagation Speed ◽  
Step Length ◽  
Experimental Investigations ◽  
Small Length ◽  
Return Stroke ◽  
Subsequent Formation ◽  
Peak Current ◽  
Model Based

A physical model based on the mechanism observed in experimental investigations is introduced to describe the formation of negative leader steps. Starting with a small length of a space leader located at the periphery of the negative streamer system of the stepped leader the model simulates the growth and the subsequent formation of the leader step. Based on the model, the average step length, the average step forming time and the average stepped leader propagation speed is estimated as a function of prospective return stroke peak current. The results show that the average step length and the average leader speed increases with increasing prospective return stroke current. The results also show that the speed of the stepped leader increases as it approaches the ground. For a 30 kA prospective return stroke current the average leader speed obtained is about 5 x 105 m/s and the average step length was about 10 m. The results obtained are in reasonable agreement with the experimental observations. 

scholarly journals Lightning Return-Stroke Transmission Line Modelling Based on the Derivative of Heidler Function and CN Tower Data

2021 ◽  
Author(s):  
Mariusz Milewski
Keyword(s):  
Transmission Line ◽  
Telecommunication Networks ◽  
Stroke Model ◽  
Return Stroke ◽  
Measured Current ◽  
Lightning Current ◽  
Current Parameter ◽  
Measured Field ◽  
Current Characteristics ◽  
Current Derivative

One of the most important parameters in a lightning flash that is of interest to researchers is the lightning return-stroke current as it causes most of the destructions and disturbances in electrical and telecommunication networks. In most cases, the lightning return-stroke current can not be directly measured and current characteristics are determined from measured electric and magnetic fields through the use of lightning return-stroke models. The main objective of this work is the development of a lightning return-stroke model for an elevated object. Also, an important objective is the correlation of the wavefront parameters (peak, maximum rate of rise and risetime) of the return-stroke current with the wavefront parameters of its associated lightning electromagnetic pulse (LEMP), measured 2 km north of the tower. The developed field-current parameter relationships for CN Tower lightning return strokes are compared with those obtained from measurements conducted at the Peissenberg Tower in Germany. A 3-section transmission line (TL) model of the CN Tower, along with the derivative of the modified Heidler function, is used to simulate the measured current derivative signal. Then, the spatial-temporal distribution of the lightning current along the CN Tower and the lightning channel, during the lightning return-stroke phase, is determined. The presented model simulates the measured current derivative signal instead of the current as has been used by other researchers. The use of the derivative of the modified Heidler function to simulate the lightning current derivative proved to be superior than simulating the lightning current. For the quantitative assessment of the proposed model, a comparison between the simulated field, obtained through the usage of Maxwell’s equations and the simulated current, and the measured field is performed. The developed 3-section TL model based on the measured current derivative and the derivative of the modified Heidler function produced a simulated magnetic field that is much closer to the measured field in comparison with previous models. The developed field-current parameter relationships as well as the experimentally verified lightning return-stroke model can contribute to solving the inverse-source problem, one of the most challenging problems in lightning research, where the lightning current characteristics are estimated based on the characteristics of the measured LEMP.

scholarly journals Calculation of the channel discharge function for the generalized lightning traveling current source return stroke model

Filomat ◽  
2018 ◽  
Vol 32 (20) ◽  
pp. 6937-6951 ◽  
Author(s):  
Dragan Pavlovic ◽  
Gradimir Milovanovic ◽  
Jovan Cvetic
Keyword(s):  
Transmission Line ◽  
Numerical Method ◽  
Current Source ◽  
Stroke Model ◽  
Propagation Models ◽  
Return Stroke ◽  
Current Generation ◽  
Special Cases ◽  
Stroke Models ◽  
Source Models

The generalized lightning traveling current source return stroke model (also called GTCS model) represents generalization of all engineering lightning return stroke models that is generalization of the transmission line (TL models, also called current propagation models) and traveling current source models (TCS models, also known as current generation models). The channel discharge function was introduced and calculated for special cases within the GTCS model. We applied new numerical method for the calculation of the channel discharge function. The proposed method is highly accurate, extremely efficient and relatively simple.

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