Modelling electromagnetic induction via accelerated electron motion

2015 ◽  
Vol 93 (7) ◽  
pp. 802-806 ◽  
Author(s):  
Ray T. Smith ◽  
Stephen Taylor ◽  
Simon Maher

The two forms of electromagnetic induction are generally referred to as motional and transformer induction, and although these phenomena have been observed and discussed for well over 150 years, certain aspects remain controversial in the scientific literature. It is well-known that an electromotive force (emf) is induced in a loop of wire encircling a long solenoid carrying alternating current. This is true however even in a region in which there is a negligibly small magnetic or electric field. Although the flux linking concept can explain the induced emf, more recent explanations utilise the concept of vector potential as the causal explanation of induction. In this present investigation, we propose that Weber’s force, based on inter-particle forces, provides a more fundamental explanation. The induced emf is measured directly across a closely wound, 1000 turn narrow coil encircling a long solenoid carrying alternating current. Weber’s force formula has been adapted to the case of transformer induction by treating the solenoid as a stack of current loops and applying the principle of superposition. Analytical calculation is also included for the application of Faraday’s law. Close agreement with experimentally measured values is demonstrated in all cases for low-frequency induction up to around 5 kHz.

Author(s):  
Ray T. Smith ◽  
Fred P. M. Jjunju ◽  
Iain S. Young ◽  
Stephen Taylor ◽  
Simon Maher

A physical model of electromagnetic induction is developed which relates directly the forces between electrons in the transmitter and receiver windings of concentric coaxial finite coils in the near-field region. By applying the principle of superposition, the contributions from accelerating electrons in successive current loops are summed, allowing the peak-induced voltage in the receiver to be accurately predicted. Results show good agreement between theory and experiment for various receivers of different radii up to five times that of the transmitter. The limitations of the linear theory of electromagnetic induction are discussed in terms of the non-uniform current distribution caused by the skin effect. In particular, the explanation in terms of electromagnetic energy and Poynting’s theorem is contrasted with a more direct explanation based on variable filament induction across the conductor cross section. As the direct physical model developed herein deals only with forces between discrete current elements, it can be readily adapted to suit different coil geometries and is widely applicable in various fields of research such as near-field communications, antenna design, wireless power transfer, sensor applications and beyond.


Author(s):  
Jianqi Li ◽  
Yu Zhou ◽  
Jianying Li

This paper presented a novel analytical method for calculating magnetic field in the slotted air gap of spoke-type permanent-magnet machines using conformal mapping. Firstly, flux density without slots and complex relative air-gap permeance of slotted air gap are derived from conformal transformation separately. Secondly, they are combined in order to obtain normalized flux density taking account into the slots effect. The finite element (FE) results confirmed the validity of the analytical method for predicting magnetic field and back electromotive force (BEMF) in the slotted air gap of spoke-type permanent-magnet machines. In comparison with FE result, the analytical solution yields higher peak value of cogging torque.


2021 ◽  
pp. 106-114
Author(s):  
M.M. Zablodsky ◽  
◽  
P.B. Klendiy ◽  
O. P. Dudar ◽  
◽  
...  

The article considers the issue of studying the value of pH, substrate in the process of methane fermentation in the mesophilic regime and the influence of the electromagnetic field of industrial frequency. The aim is to investigate the influence of electromagnetic fields on the pH value of the substrate during fermentation. Different types of microorganisms are involved in the process of methanogenesis, and the decisive role in it is played by methane-forming archaea, which are most sensitive to pH and should be in the range of 6.5 - 8. Therefore, it is necessary to check the effect of low frequency electromagnetic field on substrate pH. The study was performed for 25 days on two substrates, one of which was exposed to a low-frequency electromagnetic field with an electromagnetic induction of 3.5 mT. The research results show that the pH value of the substrate exposed to the electromagnetic field during the methane fermentation process was within acceptable limits, and the second substrate decreased, that is, it was acidified. Key words: methane fermentation, substrate, pH value, electromagnetic field


2016 ◽  
Vol 64 (6) ◽  
pp. 2322-2336 ◽  
Author(s):  
Szymon Oryński ◽  
Marta Okoń ◽  
Wojciech Klityński

2021 ◽  
Vol 74 (1) ◽  
Author(s):  
Áine Rowe ◽  
Sharon Flanagan ◽  
Gerald Barry ◽  
Lisa M. Katz ◽  
Elizabeth A. Lane ◽  
...  

Abstract Background Warmblood Fragile Foal Syndrome (WFFS) is an autosomal recessive disorder caused by a mutation in the procollagen-lysine, 2-oxoglutarate 5-dioxygenase 1 (PLOD1) gene. Homozygosity for the mutation results in defective collagen synthesis which clinically manifests as the birth of non viable or still born foals with abnormally fragile skin. While the mutation has been identified in non Warmblood breeds including the Thoroughbred, to date all homozygous clinically affected cases reported in the scientific literature are Warmblood foals. The objective of this study was to investigate the carrier frequency of the mutation in the Thoroughbred and sport horse populations in Ireland. Methods A test was developed at the UCD School of Veterinary Medicine using real-time PCR to amplify the PLOD1 gene c.2032G > A variant. A subset of the samples was also submitted to an external laboratory with a licensed commercial WFFS genetic test. Results Warmblood Fragile Foal Syndrome genotyping was performed on hair samples from 469 horses representing 6 different breeds. Six of 303 (1.98%) sport horses tested and three of 109 (2.75%) Thoroughbreds tested were heterozygous for the WFFS polymorphism (N/WFFS). The WFFS polymorphism was not identified in the Standardbred, Cob, Connemara, or other pony breeds. Conclusions The study identified a low frequency of the WFFS causative mutation in sport horses and Thoroughbreds in Ireland, highlighting the importance of WFFS genetic testing in order to identify phenotypically normal heterozygous carriers and to prevent the birth of nonviable foals.


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