scholarly journals Measurement of the transient shielding effectiveness of shielding cabinets

2008 ◽  
Vol 6 ◽  
pp. 293-298 ◽  
Author(s):  
H. Herlemann ◽  
M. Koch
Keyword(s):  
Numerical Simulations ◽  
Electromagnetic Fields ◽  
High Frequency ◽  
Comsol Multiphysics ◽  
Magnetic Shielding ◽  
Shielding Effectiveness ◽  
Transient Electromagnetic ◽  
Electric And Magnetic Fields ◽  
Numerical Tools ◽  
Gtem Cell

Abstract. Recently, new definitions of shielding effectiveness (SE) for high-frequency and transient electromagnetic fields were introduced by Klinkenbusch (2005). Analytical results were shown for closed as well as for non closed cylindrical shields. In the present work, the shielding performance of different shielding cabinets is investigated by means of numerical simulations and measurements inside a fully anechoic chamber and a GTEM-cell. For the GTEM-cell-measurements, a downscaled model of the shielding cabinet is used. For the simulations, the numerical tools CONCEPT II and COMSOL MULTIPHYSICS were available. The numerical results agree well with the measurements. They can be used to interpret the behaviour of the shielding effectiveness of enclosures as function of frequency. From the measurement of the electric and magnetic fields with and without the enclosure in place, the electric and magnetic shielding effectiveness as well as the transient shielding effectiveness of the enclosure are calculated. The transient SE of four different shielding cabinets is determined and discussed.

scholarly journals Measurement of the transient shielding effectiveness of enclosures using UWB pulses inside an open TEM waveguide

2007 ◽  
Vol 5 ◽  
pp. 75-79 ◽  
Author(s):  
H. Herlemann ◽  
M. Koch
Keyword(s):  
Electromagnetic Field ◽  
High Frequency ◽  
Measurement Procedure ◽  
Ultra Wideband ◽  
Magnetic Shielding ◽  
Shielding Effectiveness ◽  
Transient Electromagnetic ◽  
Electric And Magnetic Fields ◽  
Conductive Textile ◽  
Shielding Material

Abstract. Recently, new definitions of shielding effectiveness (SE) for high-frequency and transient electromagnetic fields were introduced by Klinkenbusch (2005). Numerical results were shown for closed as well as for non closed cylindrical shields. In the present work, a measurement procedure is introduced using ultra wideband (UWB) electromagnetic field pulses. The procedure provides a quick way to determine the transient shielding effectiveness of an enclosure without performing time consuming frequency domain measurements. For demonstration, a cylindrical enclosure made of conductive textile is examined. The field pulses are generated inside an open TEM-waveguide. From the measurement of the transient electric and magnetic fields with and without the shield in place, the electric and magnetic shielding effectiveness of the shielding material as well as the transient shielding effectiveness of the enclosure are derived.

Method of high frequency therapy at cows' mastitis during machine milking

2020 ◽  
pp. 9-12
Author(s):  
Viktor E. Lyubimov ◽  
Keyword(s):  
Dairy Cows ◽  
Electromagnetic Fields ◽  
High Frequency ◽  
High Efficiency ◽  
Environmentally Friendly ◽  
Ultrahigh Frequency ◽  
Machine Milking ◽  
High Frequency Electromagnetic Field ◽  
Milking Machine ◽  
Methods Of Treatment

Health of dairy cows ensures human health, so it is important that dairy products do not contain antibiotics that are used to treat any inflammation, including mastitis. In Russia at present, the problem of mastitis in cows exists with both attached and loose housing of cows. Mastitis of dairy cows are the great problem in milking husbandry. Losses from mastitis in milk yield can reach 15-20%. The main reasons for the occurrence of nonspecific mastitis of cows are the shortcomings of the working components of the milking machine: the degree of deterioration of the nipple rubber and the violation of machine milking technology (the reduction in pre-milking time and vacuum fluctuations account for 70% of all causes). Treatment of mastitis with antibiotics is effective, but not environmentally friendly and unacceptable. For the treatment of inflammation of the udder, it is necessary to use more environmentally friendly methods of treatment, one of which is the exposure to ultra-high frequency electromagnetic field tested by medicine. Use of three types of medical-mobile milking machines with the same method of exposure to ultrahigh-frequency electromagnetic fields on cow's nipples through electrodes in milking cups: LPDA-1-UHF, LPDA-2-UHF and LPDA-UHF-30 M, is described in the article. Author proved that cows with subclinical forms of mastitis recovered faster during milking with exposure to the ultrahigh frequency than when treated by antibiotics, and milking with the ultrahigh frequency device helps to recover 82% of the affected quarters with clinical forms and 100% of cows with subclinical forms of mastitis or with udder irritation. The high efficiency of the method of exposure to electromagnetic fields of the ultrahigh frequency during machine milking by means of medical-mobile milking machines LPDA-UHF for the prevention and treatment of mastitis of cows was shown.

Simulation-based assessment of coupled frequency response of magneto-electro-elastic auxetic multifunctional structures subjected to various electromagnetic circuits

2021 ◽  
pp. 146442072110219
Author(s):  
Vinyas Mahesh ◽  
Vishwas Mahesh ◽  
Dineshkumar Harursampath ◽  
Ahmed E Abouelregal
Keyword(s):  
Electric Fields ◽  
Solid Mechanics ◽  
Natural Frequencies ◽  
Comsol Multiphysics ◽  
Simulation Based ◽  
Electric And Magnetic Fields ◽  
Auxetic Structures ◽  
Triangular Elements ◽  
Benchmark Solutions ◽  
Free Vibration Response

This article deals with the modeling of magneto-electro-elastic auxetic structures and developing a methodology in COMSOL Multiphysics® to assess the free vibration response of such structures when subjected to various electromagnetic circuit conditions. The triple energy interaction between elastic, magnetic, and electric fields are established in the COMSOL Multiphysics® using structural mechanics and electromagnetic modules. The multiphase magneto-electro-elastic material with different percentages of piezoelectric and piezomagnetic phases are used as the material. In the solid mechanics module, the piezoelectric and piezomagnetic materials were created in stress-charge and stress-magnetization forms, respectively. The electric and magnetic fields are defined in COMSOL Multiphysics® through electromagnetic equations. Further, the customized controlled meshing constituted of free tetrahedral and triangular elements is adapted to trade-off between the accuracy and the computational expenses. The eigenvalue analysis is performed to obtain the natural frequencies of the MEE re-entrant auxetic structures. Also, the efficiency of smart auxetic structures over conventional honeycomb structures is presented throughout the manuscript. In addition, the discrepancy in the natural frequencies of the structures considering coupled and uncoupled state is also illustrated. It is believed that the modeling procedure and its outcomes serve as benchmark solutions for further design and analysis of smart auxetic magneto-electro-elastic structures.

scholarly journals The perturbation of electromagnetic fields at distances that are large compared with the object's size

2014 ◽  
Vol 80 (3) ◽  
pp. 865-892 ◽  
Author(s):  
Paul D Ledger ◽  
William R B Lionheart
Keyword(s):  
Magnetic Fields ◽  
Electromagnetic Fields ◽  
Asymptotic Expansions ◽  
Low Frequency ◽  
Perfect Conductor ◽  
Small Object ◽  
Leading Order ◽  
Material Parameters ◽  
Electric And Magnetic Fields

Abstract We rigorously derive the leading-order terms in asymptotic expansions for the scattered electric and magnetic fields in the presence of a small object at distances that are large compared with its size. Our expansions hold for fixed wavenumber when the scatterer is a (lossy) homogeneous dielectric object with constant material parameters or a perfect conductor. We also derive the corresponding leading-order terms in expansions for the fields for a low-frequency problem when the scatterer is a non-lossy homogeneous dielectric object with constant material parameters or a perfect conductor. In each case, we express our results in terms of polarization tensors.

scholarly journals Finite element modelling of transient electromagnetic fields near steel-cased wells

2015 ◽  
Vol 202 (2) ◽  
pp. 901-913 ◽  
Author(s):  
Evan Schankee Um ◽  
Michael Commer ◽  
Gregory A. Newman ◽  
G. Michael Hoversten
Keyword(s):  
Finite Element ◽  
Electromagnetic Fields ◽  
Finite Element Modelling ◽  
Element Modelling ◽  
Transient Electromagnetic
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