| 1. |
- Ahmad, Noor Azlinda, 1978-, et al.
(author)
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Radiation Field Spectra of Long-duration Cloud Flashes
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In: IEEE transactions on electromagnetic compatibility (Print). - 0018-9375 .- 1558-187X.
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Journal article (peer-reviewed)abstract
- The radiation electric fields produced by long-duration cloud flashes have been Fourier analyzed to determined the frequency spectrum in the range of 10 kHz to 10 MHz. The flashes were recorded within a distance of less than 20 km. The spectrum was normalized to 50 km distance and it shows a f-1 dependence within the entire frequency range.
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| 2. |
- Becerra, Marley, et al.
(author)
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On the interaction of lightning upward connecting positive leaders with humans
- 2009
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In: IEEE transactions on electromagnetic compatibility (Print). - USA : IEEE. - 0018-9375 .- 1558-187X. ; 51:4, s. 1001-1008
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Journal article (peer-reviewed)abstract
- Upward connecting leaders can be initiated from humans under the influence of lightning downward stepped leaders, thereby causing severe injuries. In order to improve the scarce knowledge about the interaction of upward connecting leaders with humans, a self-consistent model based on the physics of leader discharges is used in this paper. Furthermore, a current-generation-type return-stroke model is applied to calculate the current pulse produced during the neutralization of unsuccessful aborted upward leaders. It is estimated that an upward connecting leader can be initiated even when the victim is located several tens of meters away from the lightning channel. However, the lightning exposure to a direct strike and to an aborted leader is found to be reduced by 50% and 70%, respectively, when an individual standing straight adopts the squat position. In the case of an aborted upward leader, it is estimated that a short-duration pulse of opposite polarity in the kiloampere range would be produced by the neutralization of the leader charge. Rough estimates of the total energy dissipated in the victim's body by the current of an aborted unsuccessful upward leader range between hundred and thousand joules.
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| 3. |
- Carlberg, Ulf, 1978, et al.
(author)
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Numerical study of position stirring and frequency stirring in loaded reverberation chamber
- 2009
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In: IEEE Transactions on Electromagnetic Compatibility. - 0018-9375 .- 1558-187X. ; 51:1, s. pp. 12-17
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Journal article (peer-reviewed)abstract
- A numerical model of a loaded reverberation chamber is used to study the effectiveness of 3-D position stirring and frequency stirring. The numerical model is based on thin wires, the moment method, and a cavity Green's function. The average power transfer level between two dipole antennas is compared to the average power transfer level between a dipole antenna and a loop antenna. The two transmission levels should ideally be the same, as both the dipole and the loop are treated as being lossless and impedance matched. The standard deviation of the level differences is a measure of the accuracy of the chamber, and this is used to estimate the stirring effectiveness. It is shown that frequency stirring must be done over a larger bandwidth than the average mode bandwidth to be effective. The 3-D position stirring is also shown to be much more efficient than expected.
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| 4. |
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| 5. |
- Carlsson, Jan, 1962, et al.
(author)
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Transmission through corrugated slots
- 1995
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In: IEEE Transactions on Electromagnetic Compatibility. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9375 .- 1558-187X. ; 37:1, s. 114-121
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Journal article (peer-reviewed)
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| 6. |
- Colombi, Davide, et al.
(author)
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Efficient Whole-Body SAR Assessments by Means of Surface Scan Measurements
- 2014
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In: IEEE transactions on electromagnetic compatibility (Print). - 0018-9375 .- 1558-187X. ; 56:3, s. 539-548
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Journal article (peer-reviewed)abstract
- In this study, an experimental method has been investigated for efficient assessments of whole-body specific absorption rates (SAR) from radio base station antennas. Using surface amplitude measurements of the electric field components together with an integral equation technique, a method is obtained which is not biased to specific antenna designs or phantom shapes. For realistic material parameters, it has been found that only the amplitude of the tangential field components over the phantom boundary is needed to accurately assess whole-body SAR, which makes the proposed method well suited for integration with commercially available SAR measurement systems. The method has been validated with simulations and measurements. Compared with a volumetric scan, and for the cases investigated, the measurement time was reduced with a factor larger than 3 while keeping the relative error smaller than 8%.
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| 7. |
- Cooray, Vernon
(author)
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A novel procedure to represent lightning return strokes : current dissipation return stroke models
- 2009
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In: IEEE transactions on electromagnetic compatibility (Print). - USA : IEEE. - 0018-9375 .- 1558-187X. ; 51:3, s. 748-755
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Journal article (peer-reviewed)abstract
- Engineering return stroke models available in the literature can be divided into two categories, namely, current propagation models and current generation models. Based on the theory of pulse propagation along transmission lines in the presence of corona, a third procedure to describe return strokes, which, in fact, is the inverse of current generation models, is introduced. Models based on the new concept are called current dissipation models. In the current generation models, the corona currents generated by the neutralization of the corona sheath travel downward and the cumulative effects of these corona currents generate the return stroke current. In current dissipation models, the return stroke is initiated by a current pulse injected into the core of the leader channel at ground level. This injected current pulse travels upward with speed vc . If the return stroke channel is treated as a transmission line, then this speed is equal to the speed of light. The propagation of this pulse along the central core initiates the neutralization of the corona sheath leading to the release of corona currents into the central core. In contrast to current generation models in which corona currents travel downward, these corona currents travel upward along the core. The speed of propagation of the corona pulses upward along the core is also equal to vc. The corona currents, being of opposite polarity, lead to the dissipation of the injected current pulse. As in the case of current generation models, a current dissipation model can be described completely by any three of the following four parameters. They are: 1) channel base current; 2) spatial variation of the return stroke velocity; 3) spatial variation of the corona decay time constant; and 4) the spatial variation of the positive charge deposited by the return stroke on the leader channel. It is also shown that current propagation models available in the literature are special cases of current dissipation models.
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| 8. |
- Cooray, Vernon, et al.
(author)
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Engineering Lightning Return Stroke Models Incorporating Current Reflection From Ground and Finitely Conducting Ground Effects
- 2011
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In: IEEE transactions on electromagnetic compatibility (Print). - 0018-9375 .- 1558-187X. ; 53:3, s. 773-781
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Journal article (peer-reviewed)abstract
- A return stroke model that incorporates a reflected wave from ground without introducing any current discontinuities at the return stroke front is introduced. The incident current is treated using current generation concepts and the reflected current using current dissipation concepts. It is shown that the effect of the reflected current wave is to cause flattening of close electric field waveforms within about 10 mu s. Additionally, it is shown how a return stroke model could be utilized to study the effect of ground conductivity on the return stroke current. The results show that the peak time derivative of current in lightning strokes terminating on poorly conducting ground is significantly lower than in the case of highly conducting ground. The model is also used to predict the spatial variation of return stroke velocity. The results show that the return stroke velocity increases initially, reaches a peak, and then decays with increasing height.
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| 9. |
- Cooray, Vernon, 1952-, et al.
(author)
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Field-to-Transmission Line Coupling Models With Special Attention to the Cooray-Rubinstein Approximation
- 2021
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In: IEEE transactions on electromagnetic compatibility (Print). - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9375 .- 1558-187X. ; 63:2, s. 484-493
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Journal article (peer-reviewed)abstract
- There are three equivalent procedures to evaluate the voltages induced by lightning on power lines, namely, the Agrawal-Price-Gurbaxani model, the Taylor-Satterwhite-Harrison model, and the Rachidi model. The Cooray-Rubinstein approximation is a procedure used by scientists and engineers to estimate the horizontal electric field from the lightning that is used in the induced voltage calculations for lines located over a finitely conducting ground. The Cooray-Rubinstein approximation is usually incorporated in calculating the induced overvoltages using the Agrawal-Price-Gurbaxani model. In this article, it is shown how this approximation could be incorporated into the other two coupling models. The resulting coupling equations are compared to each other by calculating the voltages induced on two idealized overhead transmission lines.
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| 10. |
- Cooray, Vernon, 1952-, et al.
(author)
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Formulation of the Field-to-Transmission Line Coupling Equations in Terms of Scalar and Vector Potentials
- 2017
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In: IEEE transactions on electromagnetic compatibility (Print). - 0018-9375 .- 1558-187X. ; 59:5, s. 1586-1591
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Journal article (peer-reviewed)abstract
- More than 60 years ago, Prof. S. Rusck introduced a coupling model to take into account the interaction of lightning-generated electromagnetic fields with overhead power transmission and distribution lines. The model which assumes that the ground is perfectly conducting has served the power system research community for many decades. Recently, it was found that this model is not complete because some of the forcing terms in the relevant transmission line equations, which are based purely on the scalar and vector potentials, were missing. In the present paper, the correct transmission line equations pertinent to the interaction of external electromagnetic fields with overhead lines, described in terms of scalar and vector potentials, are derived by incorporating the effects of a finitely conducting ground. The model presented in this paper can be considered as a correction and an extension of the Rusck model to account for a finitely conducting ground.
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