The Experts below are selected from a list of 4527 Experts worldwide ranked by ideXlab platform

Muhammad Zeshan Qasim - One of the best experts on this subject based on the ideXlab platform.

L Grcev - One of the best experts on this subject based on the ideXlab platform.

  • plane wave coupling to Horizontal Wire above lossy soil comparison of electromagnetic complex image and transmission line models
    Facta Universitatis Series: Automatic Control and Robotics, 2013
    Co-Authors: Vesna Arnautovski Tosheva, L Grcev
    Abstract:

    The paper presents modeling of TM plane coupling to Horizontal thin-Wire conductor above homogeneous lossy soil. The main purpose of this work is to compare results of the current distribution obtained by using two approximate approaches based on: complex image theory and transmission line theory with respect to a rigorous electromagnetic approach. A detailed parametric analysis clearly illustrates the validity domain and possible limitations of approximate models in EMC studies.

  • comparison of image and transmission line models of energized Horizontal Wire above two layer soil
    Automatika: Journal for Control Measurement Electronics Computing and Communications, 2012
    Co-Authors: Vesna Arnautovskitoseva, Khalil El Khamlichi Drissi, Kamal Kerroum, Solza Grceva, L Grcev
    Abstract:

    The paper presents comparison between two approximate models of energized Horizontal thin-Wire conductors above two-layer soil. The formulation is posed in frequency domain by using two approaches. The first one is based on quasi-static image theory within Mixed Potential Integral Equation. The second one is based on transmission line theory with approximation of per unit length parameters. The authors compare currents computed by the both approximate models of a center fed Wire to establish the computation errors over a wide frequency range. The main objective is to validate the proposed image and transmission line models for various lengths of Wire conductors, and various cases of low and high conductivities of two-layer soil. The verification of the results is done by comparison with exact model based on full-wave theory. Detailed parametric analysis clearly illustrate validity domain and problems when using both approximate models with respect to their use in practical EMC studies.

Leonid Grcev - One of the best experts on this subject based on the ideXlab platform.

  • On the Image Model of a Buried Horizontal Wire
    IEEE Transactions on Electromagnetic Compatibility, 2016
    Co-Authors: Vesna Arnautovski-toseva, Leonid Grcev
    Abstract:

    It is common practice in the engineering analysis process to use an approximate image method for the computation of the current in buried Horizontal conductors (in the literature, this is often referred to as the “modified image” or “reflection coefficient” method). According to this approach, the earth/air interface is replaced by a positive mirror image of the charge and current in the conductor, and its field is multiplied by a suitable reflection coefficient. Different opinions on the validity of this approximation have been expressed in published debates, but more systematic analysis of the error introduced by this approach is not available in the literature. To establish the amount of error, we compare the computation results of the image model with the rigorous Sommerfeld integral method for a wide range of parameters. Contrary to widespread opinion, our results suggest that the modified image (or reflection coefficient) method in EFIE-based solutions (e.g., the Pocklington equation) leads to a large error (larger than 20%) in the low-frequency range for the computation of the current distribution in conductors longer than 10 m. In such a case, MPIE-based methods are preferred for use to achieve a smaller error (approximately 5%). Guidelines for the application of image models related to the conductor, earth and excitation parameters, upper frequency limit, and modeling method are presented.

  • On the Image Model of a Buried Horizontal Wire
    IEEE Transactions on Electromagnetic Compatibility, 2016
    Co-Authors: Vesna Arnautovski-toseva, Leonid Grcev
    Abstract:

    It is common practice in the engineering analysis process to use an approximate image method for the computation of the current in buried Horizontal conductors (in the literature, this is often referred to as the “modified image” or “reflection coefficient” method). According to this approach, the earth/air interface is replaced by a positive mirror image of the charge and current in the conductor, and its field is multiplied by a suitable reflection coefficient. Different opinions on the validity of this approximation have been expressed in published debates, but more systematic analysis of the error introduced by this approach is not available in the literature. To establish the amount of error, we compare the computation results of the image model with the rigorous Sommerfeld integral method for a wide range of parameters. Contrary to widespread opinion, our results suggest that the modified image (or reflection coefficient) method in EFIE-based solutions (e.g., the Pocklington equation) leads to a large error (larger than 20%) in the low-frequency range for the computation of the current distribution in conductors longer than 10 m. In such a case, MPIE-based methods are preferred for use to achieve a smaller error (approximately 5%). Guidelines for the application of image models related to the conductor, earth and excitation parameters, upper frequency limit, and modeling method are presented.

  • Applicability of approximate Green's functions in MPIE model of a Horizontal Wire conductor in lossy soil
    Przegląd Elektrotechniczny, 2014
    Co-Authors: Vesna Arnautovski-toseva, Leonid Grcev, M. Kacarska
    Abstract:

    The paper presents a study of the applicability of approximate Green's functions in frequency domain analysis of a Horizontal Wire conductor above or buried in homogeneous lossy soil. The authors analyze the effects of two distinct approximate formulations of Sommerfeld integrals based on the use of quasi-static image theory and complex image theory. This analysis is focused on the current distribution with respect to conductor length and position, soil parameters and frequency range. Streszczenie. W artykule przedstawiono badania nad zastosowaniem przyblizonych funkcji Greena w analizie czestotliwościowej poziomych przewodow usytuowanych nad lub zakopanych w jednorodnej stratnej ziemi. Autorzy przeanalizowali efekty dwoch przyblizonych sformulowan calek Sommerfelda w oparciu o kwasistatyczną teorie odbic i kompleksową teorie odbic. Skupiono sie na analizie rozkladu prądu z odniesieniem do dlugości przewodnika i jego pozycji, parametrow gleby i zakresu czestotliwości. (Stosowalnośc przyblizonych funkcji Greena w MPIE modelach poziomych przewodow w stratnej glebie)

  • Comparison of approximate models of Horizontal Wire conductor above homogeneous ground
    2012 6th European Conference on Antennas and Propagation (EUCAP), 2012
    Co-Authors: Vesna Arnautovski-toseva, Khalil El Khamlichi Drissi, Kamal Kerroum, Leonid Grcev
    Abstract:

    The paper presents comparison between approximate models of Horizontal Wire conductor above homogeneous lossy ground based on image theory and transmission line theory. The main objective of this study is to indicate the cases of applicability of the proposed approximate models in practical EMC studies. The results are verified by comparison with exact model based on the electromagnetic theory.

  • Electromagnetic analysis of Horizontal Wire in two-layered soil
    Journal of Computational and Applied Mathematics, 2004
    Co-Authors: Vesna Arnautovski-toseva, Leonid Grcev
    Abstract:

    Simulation of grounding systems at high frequencies is of interest in electromagnetic compatibility, especially related to lightning, and in emerging technologies, such as power line telecommunications. This paper presents first results in the effort to extend the electromagnetic field theory based modeling of grounding systems to a two-layer model of earth. A rigorous mathematical model which solution involves numerical solution of Sommerfeld-type integrals is described. Also new more approximate but computationally more efficient solution based on quasi-static image theory is introduced. Comparison between these two solutions led to conclusion related to the applicability of the image theory approach, which may be of interest for practical problems.

John W. Rose - One of the best experts on this subject based on the ideXlab platform.

  • Condensation on a Horizontal Wire-Wrapped Tube
    Journal of Heat Transfer, 2005
    Co-Authors: Takahiro Murase, Adrian Briggs, Hua Sheng Wang, John W. Rose
    Abstract:

    Measurements for film condensation of steam, R113 and ethylene glycol on a Horizontal Wire-wrapped tube are reported. All measurements were made at near atmospheric vapor pressure and with coolant at around 20 °C. Care was taken to avoid error due to the presence of air in the vapor. Complete wetting (film condensation) was observed in all cases. Wire diameter and pitch of winding were systematically varied and heat-transfer measurements made for a range of coolant flow rates. Data, in the form of heat flux and vapor-to-surface temperature difference, are presented. These were used to determine enhancement ratios (ratio of heat flux or heat-transfer coefficient for a Wire-wrapped tube to the corresponding value for a plain tube at the same vapor-to-surface temperature difference). Enhancement ratios exceeding 3 for R113 and 2 for steam and ethylene glycol were obtained. The results are discussed in the light of earlier measurements and theory.

  • An Analysis of Film Condensation on a Horizontal Wire-Wrapped Tube
    Chemical Engineering Research and Design, 2002
    Co-Authors: John W. Rose
    Abstract:

    The paper gives a provisional analysis of heat transfer during laminar film condensation on a Horizontal, Wire-wrapped tube. This preliminary report is based on an approximate, partly empirical, earlier solution 1 . The present work includes capillary condensate retention between the Wire and tube determined using the approach of Masuda and Rose 2 for condensation on integral-finned tubes. The final result is given in the form of a simple equation for the enhancement ratio (heat transfer for the Wire-wrapped tube divided by the Nusselt value for the plain tube with the same vapour-to-surface temperature difference). The theoretical enhancement ratio depends only on the tube and Wire diameters and the pitch of the winding, as well as the surface tension and density of the condensate, and is independent of the vapour-to-surface temperature difference. The expression for enhancement may readily be used to optimize the geometric variables for condensation of a given fluid. Comparison with limited available experimental data is inconclusive and indicates the need for further experimental work and scrutiny of approximations used in the model.

Vesna Arnautovski-toseva - One of the best experts on this subject based on the ideXlab platform.

  • On the Image Model of a Buried Horizontal Wire
    IEEE Transactions on Electromagnetic Compatibility, 2016
    Co-Authors: Vesna Arnautovski-toseva, Leonid Grcev
    Abstract:

    It is common practice in the engineering analysis process to use an approximate image method for the computation of the current in buried Horizontal conductors (in the literature, this is often referred to as the “modified image” or “reflection coefficient” method). According to this approach, the earth/air interface is replaced by a positive mirror image of the charge and current in the conductor, and its field is multiplied by a suitable reflection coefficient. Different opinions on the validity of this approximation have been expressed in published debates, but more systematic analysis of the error introduced by this approach is not available in the literature. To establish the amount of error, we compare the computation results of the image model with the rigorous Sommerfeld integral method for a wide range of parameters. Contrary to widespread opinion, our results suggest that the modified image (or reflection coefficient) method in EFIE-based solutions (e.g., the Pocklington equation) leads to a large error (larger than 20%) in the low-frequency range for the computation of the current distribution in conductors longer than 10 m. In such a case, MPIE-based methods are preferred for use to achieve a smaller error (approximately 5%). Guidelines for the application of image models related to the conductor, earth and excitation parameters, upper frequency limit, and modeling method are presented.

  • On the Image Model of a Buried Horizontal Wire
    IEEE Transactions on Electromagnetic Compatibility, 2016
    Co-Authors: Vesna Arnautovski-toseva, Leonid Grcev
    Abstract:

    It is common practice in the engineering analysis process to use an approximate image method for the computation of the current in buried Horizontal conductors (in the literature, this is often referred to as the “modified image” or “reflection coefficient” method). According to this approach, the earth/air interface is replaced by a positive mirror image of the charge and current in the conductor, and its field is multiplied by a suitable reflection coefficient. Different opinions on the validity of this approximation have been expressed in published debates, but more systematic analysis of the error introduced by this approach is not available in the literature. To establish the amount of error, we compare the computation results of the image model with the rigorous Sommerfeld integral method for a wide range of parameters. Contrary to widespread opinion, our results suggest that the modified image (or reflection coefficient) method in EFIE-based solutions (e.g., the Pocklington equation) leads to a large error (larger than 20%) in the low-frequency range for the computation of the current distribution in conductors longer than 10 m. In such a case, MPIE-based methods are preferred for use to achieve a smaller error (approximately 5%). Guidelines for the application of image models related to the conductor, earth and excitation parameters, upper frequency limit, and modeling method are presented.

  • Applicability of approximate Green's functions in MPIE model of a Horizontal Wire conductor in lossy soil
    Przegląd Elektrotechniczny, 2014
    Co-Authors: Vesna Arnautovski-toseva, Leonid Grcev, M. Kacarska
    Abstract:

    The paper presents a study of the applicability of approximate Green's functions in frequency domain analysis of a Horizontal Wire conductor above or buried in homogeneous lossy soil. The authors analyze the effects of two distinct approximate formulations of Sommerfeld integrals based on the use of quasi-static image theory and complex image theory. This analysis is focused on the current distribution with respect to conductor length and position, soil parameters and frequency range. Streszczenie. W artykule przedstawiono badania nad zastosowaniem przyblizonych funkcji Greena w analizie czestotliwościowej poziomych przewodow usytuowanych nad lub zakopanych w jednorodnej stratnej ziemi. Autorzy przeanalizowali efekty dwoch przyblizonych sformulowan calek Sommerfelda w oparciu o kwasistatyczną teorie odbic i kompleksową teorie odbic. Skupiono sie na analizie rozkladu prądu z odniesieniem do dlugości przewodnika i jego pozycji, parametrow gleby i zakresu czestotliwości. (Stosowalnośc przyblizonych funkcji Greena w MPIE modelach poziomych przewodow w stratnej glebie)

  • Comparison of approximate models of Horizontal Wire conductor above homogeneous ground
    2012 6th European Conference on Antennas and Propagation (EUCAP), 2012
    Co-Authors: Vesna Arnautovski-toseva, Khalil El Khamlichi Drissi, Kamal Kerroum, Leonid Grcev
    Abstract:

    The paper presents comparison between approximate models of Horizontal Wire conductor above homogeneous lossy ground based on image theory and transmission line theory. The main objective of this study is to indicate the cases of applicability of the proposed approximate models in practical EMC studies. The results are verified by comparison with exact model based on the electromagnetic theory.

  • Electromagnetic analysis of Horizontal Wire in two-layered soil
    Journal of Computational and Applied Mathematics, 2004
    Co-Authors: Vesna Arnautovski-toseva, Leonid Grcev
    Abstract:

    Simulation of grounding systems at high frequencies is of interest in electromagnetic compatibility, especially related to lightning, and in emerging technologies, such as power line telecommunications. This paper presents first results in the effort to extend the electromagnetic field theory based modeling of grounding systems to a two-layer model of earth. A rigorous mathematical model which solution involves numerical solution of Sommerfeld-type integrals is described. Also new more approximate but computationally more efficient solution based on quasi-static image theory is introduced. Comparison between these two solutions led to conclusion related to the applicability of the image theory approach, which may be of interest for practical problems.