电磁分析与应用期刊(英文)最新文献_第3页

A Model for RF Loss through Vegetation with Varying Water Content 不同含水量植被的射频损耗模型

电磁分析与应用期刊(英文) Pub Date : 2021-03-31 DOI: 10.4236/JEMAA.2021.133003

S. Peden, Ronald C. Bradbury, D. Lamb, M. Hedley

{"title":"A Model for RF Loss through Vegetation with Varying Water Content","authors":"S. Peden, Ronald C. Bradbury, D. Lamb, M. Hedley","doi":"10.4236/JEMAA.2021.133003","DOIUrl":"https://doi.org/10.4236/JEMAA.2021.133003","url":null,"abstract":"Assessing plant water status is important for monitoring plant physiology. Radio signals are attenuated when passing through vegetation. Both analytical and empirical models developed for radio frequency (RF) loss through vegetation have been dependent on experimental measurements and those measurements have been completed in specific situations. However, for models to be more broadly applicable across a broad range of vegetation types and constructs, basic electrical properties of the vegetation need to be characterised. Radio waves are affected especially by water and the relationship between water content in vegetation expressed as effective water path (EWP) in mm and measured RF loss (dB) at 2.4 GHz was investigated in this work. The EWP of eucalyptus leaves of varying amounts of leaf moisture (0% - 41.5%) ranged from 0 - 14 mm, respectively. When the model was compared with the actual RF loss there was a systematic offset equivalent to a residual leaf moisture content of 6.5% that was unaccounted for in the leaf moisture content determination (oven drying). This was attributed to bound water. When the model was adjusted for this amount of additional leaf water, the average RMSE in predicted RF loss was ±2.2 dB and was found to explain 89% of the variance in measured RF loss.","PeriodicalId":58231,"journal":{"name":"电磁分析与应用期刊(英文)","volume":"76 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70292803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

Bulk Waves in the Infinite Electric-Magnetic-Elastic Plate with Mixed Boundary Conditions 混合边界条件下无限电-磁-弹板中的体波

电磁分析与应用期刊(英文) Pub Date : 2021-02-28 DOI: 10.4236/JEMAA.2021.132002

Genquan Xie, Xingpeng Song, Xiao Xiao

引用次数: 0

Finite Element CAD Experiments on the Effect of Magnetic Loss in Power Transformers with Laminated Cores 叠片铁芯电力变压器磁损耗影响的有限元CAD实验

电磁分析与应用期刊(英文) Pub Date : 2021-01-28 DOI: 10.4236/JEMAA.2021.131001

Antônio Flavio Licarião Nogueira, R. Weinert, Leonardo José Amador Salas Maldonado

{"title":"Finite Element CAD Experiments on the Effect of Magnetic Loss in Power Transformers with Laminated Cores","authors":"Antônio Flavio Licarião Nogueira, R. Weinert, Leonardo José Amador Salas Maldonado","doi":"10.4236/JEMAA.2021.131001","DOIUrl":"https://doi.org/10.4236/JEMAA.2021.131001","url":null,"abstract":"The paper describes a simulated experiment that focuses on the numeric computation of magnetic loss in the laminated core of a single-phase power transformer. The students’ laboratory work is part of the library of experiments of the Electrical Machines virtual laboratory and makes use of the two-dimensional open-access electromagnetic field analysis software Finite Element Method Magnetics. The idea of the simulated exercise is to demonstrate how the magnetic loss caused by time-varying excitations affects the magnetic permeability, μ, of the laminated core and the terminal quantities of the energizing winding. A parametric analysis employing different values for the electrical conductivity and maximum hysteresis-induced angle of the laminated material yields five different field problems with increasing magnetic loss. Electric circuits characterized by the (I-V) operating point and reflected impedance of the energizing winding provide the information required to compute the changes in real power ΔP, reactive power ΔQ and magnetically stored energy ΔWm between successive problems characterized by increasing magnetic loss. The concept of reflected impedance helps to explain the physical meaning of the changes in power dissipation and energy storage in the laminated core.","PeriodicalId":58231,"journal":{"name":"电磁分析与应用期刊(英文)","volume":"13 1","pages":"1-19"},"PeriodicalIF":0.0,"publicationDate":"2021-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44597987","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

An Introductory Note on Finite Element Problems Based on the Eddy Current Testing Approach 基于涡流测试方法的有限元问题导论

电磁分析与应用期刊(英文) Pub Date : 2021-01-01 DOI: 10.4236/jemaa.2020.1311011

Antônio Flavio Licarião Nogueira, R. Weinert, Leonardo José Amador Salas Maldonado

引用次数: 0

A New Electrostatic Generator Driven by Only an Electric Field of an Electret 一种仅由驻极体电场驱动的新型静电发生器

电磁分析与应用期刊(英文) Pub Date : 2021-01-01 DOI: 10.4236/jemaa.2021.1312012

K. Sakai

引用次数: 0

Analysis of a Stochastic Emission Theory Regarding Its Ability to Explain the Effects of Special Relativity 随机发射理论解释狭义相对论效应的能力分析

电磁分析与应用期刊(英文) Pub Date : 2020-12-30 DOI: 10.4236/jemaa.2020.1212014

S. Kühn

引用次数: 2

Different Geometries of Superheterodyne Amplification of Electromagnetic Beams in Waveguides Nitride-Dielectric 波导氮化物介质中电磁束超外差放大的不同几何结构

电磁分析与应用期刊(英文) Pub Date : 2020-12-11 DOI: 10.4236/jemaa.2020.1211013

J. Escobedo-Alatorre, V. Grimalsky, S. Koshevaya, M. Tecpoyotl-Torres

引用次数: 0

Diffusion Coefficient at Resonance Frequency as Applied to n+/p/p+ Silicon Solar Cell Optimum Base Thickness Determination 共振频率下的扩散系数在n+/p/p+硅太阳能电池最佳基底厚度测定中的应用

电磁分析与应用期刊(英文) Pub Date : 2020-10-30 DOI: 10.4236/jemaa.2020.1210012

A. Ndiaye, S. Gueye, Mame Faty Mbaye Fall, G. Diop, Amadou Mamour Ba, Mamadou Lamine Ba, Ibrahima Diatta, Lemrabott Habiboullah, G. Sissoko

引用次数: 3

Design and Development of High Efficiency 150 kW Very Compact PLA Core Electromagnetic Coupler for Highly Resonant Power Transfer Technology 用于高谐振功率传输技术的高效150kW超紧凑型PLA芯电磁耦合器的设计与开发

电磁分析与应用期刊(英文) Pub Date : 2020-09-30 DOI: 10.4236/jemaa.2020.129011

F. Z. Boudara, M. Rivaletto, L. Pécastaing, A. Ferron, S. Paquet, J. Brasile

{"title":"Design and Development of High Efficiency 150 kW Very Compact PLA Core Electromagnetic Coupler for Highly Resonant Power Transfer Technology","authors":"F. Z. Boudara, M. Rivaletto, L. Pécastaing, A. Ferron, S. Paquet, J. Brasile","doi":"10.4236/jemaa.2020.129011","DOIUrl":"https://doi.org/10.4236/jemaa.2020.129011","url":null,"abstract":"Highly Resonant Power Transfer (HRPT) technology is currently receiving very significant attention from the industry and the smart power grid distribution community in particular. This technology ensures electrical power transmission between two points while controlling the level of transmitted power and ensures the immediate shutdown of the transmitted power in the event of a problem. This paper reviews the inductive power transfer method and describes the design of an ultra-compact PLA core electromagnetic coupler. The proposed architecture confines the magnetic field in a toroidal PLA core transformer, and by avoiding the use of heavy and bulky shielding plates, reduces magnetic losses and avoids the Curie point. As a result, the overall unit has a weight of 5 kg and a volume of only 0.013 m3. The electromagnetic coupler is capable of transferring a peak power of 150 kW with an operating frequency of 193 kHz, giving a satisfactory efficiency of 95%. The proposed novel system was first investigated through CST 3D numerical modelling to determine the electrical parameters of the coupler’s equivalent circuit and its efficiency, to verify its compatibility with the ICNIRP 2010 standard and to evaluate its temperature rise with an air-cooling system. Afterwards, the designed coupler was built with a 3D printing device and finally tested experimentally. Simulation and experimental results are compared and show a good agreement.","PeriodicalId":58231,"journal":{"name":"电磁分析与应用期刊(英文)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45529643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Finite Element Analysis and Experimental Characterization of Soil Electrical Resistivity at El Roque de los Muchachos Observatory El Roque de los Muchachos天文台土壤电阻率的有限元分析与实验表征

电磁分析与应用期刊(英文) Pub Date : 2020-07-16 DOI: 10.4236/jemaa.2020.127008

Ronda Silvia, Martinez Oibar, Oliver Clara, Marquez Patricia, M. Miguel

{"title":"Finite Element Analysis and Experimental Characterization of Soil Electrical Resistivity at El Roque de los Muchachos Observatory","authors":"Ronda Silvia, Martinez Oibar, Oliver Clara, Marquez Patricia, M. Miguel","doi":"10.4236/jemaa.2020.127008","DOIUrl":"https://doi.org/10.4236/jemaa.2020.127008","url":null,"abstract":"This paper presents a study of the soil electrical resistivity of El Roque de los Muchachos Observatory, located in La Palma Island (Spain). This work is mainly motivated by the current plans of building an array of Cherenkov Telescopes (CTA) as well as other scientific installations, which demand low earth resistances for the operation of sensitive instruments, prevention of damage due to electrostatic discharges and protection against lightning strikes. Despite the top quality of the sky, the terrain is mostly filled of hard rocks and materials with high resistivity and hardness. No reliable data of resistivities could be found in available literature, therefore a dedicated resistivity survey onsite like the one presented here is essential to optimize the earth resistance of future installations. In this work, we present measurements done in six different locations of an area covering around 250 m × 275 m and centered on coordinates 28˚45'42.9\"N, 17˚53'28.5\"W. Low resistivity (Ωm) layers have been found at specific places and depths. The resistivity at the sites has been simulated with COMSOL Multiphysics software using two different models: a simple single layer model and a three-layer model. Agreement with measurements within 10% discrepancies was obtained in all cases. The main contributions of this work are the presentation of reliable values of soil resistivity at ORM, together with the accurate simulation of the soil profiles.","PeriodicalId":58231,"journal":{"name":"电磁分析与应用期刊(英文)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44346357","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2