Power Frequency Еlectromagnetic Fields of Electrical Installations in Buildings

2021 ◽  
pp. 56-61
Author(s):  
VN Nikitina ◽  
NI Kalinina ◽  
GG Lyashko ◽  
EN Dubrovskaya ◽  
VP Plekhanov
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Electromagnetic Fields ◽  
Electric Fields ◽  
Residential Buildings ◽  
Electrical Equipment ◽  
Current Load ◽  
Public Buildings ◽  
Magnetic Field Gradients ◽  
Power Frequency

Introduction: All components of the power supply system are sources of electric and magnetic fields of industrial frequency of 50 Hz, both posing risks to human health. Estimation of predicted magnetic field levels from switchboards and transformers inside buildings is challenging and implies the importance of full-scale measurements of electromagnetic fields from built-in electrical equipment. Objectives: To establish the levels of 50 Hz electromagnetic fields during operation of built-in electrical installations in industrial, public, and residential premises. Materials and methods: We studied 50 Hz electromagnetic fields generated by electrical installations located in buildings. EMF levels were measured near transformers, switchboards, and switchgear. The electromagnetic situation in the rooms above the electrical equipment was investigated. The assessment of EMF levels was carried out in accordance with the current hygienic standards. Results: The intensity of electric fields near the equipment and in the surveyed premises was significantly lower than that of magnetic fields. The excess of maximum permissible levels at workplaces of operators servicing EMF sources in residential buildings was not detected. In the rooms of public buildings located above electrical installations, measured values of magnetic field induction ranged from 0.18 to 31 µT. The intensity of magnetic fields depended on the current load and the distance from EMF sources. Discussion: Electromagnetic field intensity depends on specifications of equipment, current loads, and distances from the sources of electromagnetic fields. Induction of 50 Hz magnetic fields in adjacent rooms may exceed hygienic standards set for residential and public buildings. Additional adverse factors include instability of magnetic fields caused by current load changes and significant magnetic field gradients in premises.

Nuclear magnetic resonance microscopy

1989 ◽  
Vol 47 ◽  
pp. 828-829
Author(s):  
Paul C. Lauterbur
Keyword(s):  
Magnetic Field ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Fields ◽  
Signal To Noise ◽  
Field Gradients ◽  
Useful Signal ◽  
Magnetic Field Gradients ◽  
Observation Times ◽  
Nuclear Magnetic

Nuclear magnetic resonance imaging can reach microscopic resolution, as was noted many years ago, but the first serious attempt to explore the limits of the possibilities was made by Hedges. Resolution is ultimately limited under most circumstances by the signal-to-noise ratio, which is greater for small radio receiver coils, high magnetic fields and long observation times. The strongest signals in biological applications are obtained from water protons; for the usual magnetic fields used in NMR experiments (2-14 tesla), receiver coils of one to several millimeters in diameter, and observation times of a number of minutes, the volume resolution will be limited to a few hundred or thousand cubic micrometers. The proportions of voxels may be freely chosen within wide limits by varying the details of the imaging procedure. For isotropic resolution, therefore, objects of the order of (10μm) may be distinguished.Because the spatial coordinates are encoded by magnetic field gradients, the NMR resonance frequency differences, which determine the potential spatial resolution, may be made very large. As noted above, however, the corresponding volumes may become too small to give useful signal-to-noise ratios. In the presence of magnetic field gradients there will also be a loss of signal strength and resolution because molecular diffusion causes the coherence of the NMR signal to decay more rapidly than it otherwise would. This phenomenon is especially important in microscopic imaging.

A Case for Magneto Hydro Dynamics (MHD)

2001 ◽  
Author(s):  
Haim H. Bau
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Lorentz Force ◽  
Electric Fields ◽  
Biological Fluids ◽  
Fluid Volume ◽  
Chaotic Advection ◽  
Complex Flows ◽  
Electric Currents

Abstract In this paper, I review some of our work on the use of magneto hydrodynamics (MHD) for pumping, controlling, and stirring fluids in microdevices. In many applications, one operates with liquids that are at least slightly conductive such as biological fluids. By patterning electrodes inside flow conduits and subjecting these electrodes to potential differences, one can induce electric currents in the liquid. In the presence of a magnetic field, a Lorentz force is generated in a direction that is perpendicular to both the magnetic and electric fields. Since one has a great amount of freedom in patterning the electrodes, one can induce forces in various directions so as to generate complex flows including “guided” flows in virtual, wall-less channels. The magnetic flux generators can be either embedded in the device or be external. Despite their unfavorable scaling (the magnitude of the forces is proportional to the fluid volume), MHD offers many advantages such as the flexibility of applying forces in any desired direction and the ability to adjust the magnitude of the forces by adjusting either the electric and/or magnetic fields. We provide examples of (i) MHD pumps; (ii) controlled networks of conduits in which each conduit is equipped with a MHD actuator and by controlling the voltage applied to each actuator, one can direct the liquid to flow in any desired way without a need for valves; and (iii) MHD stirrers including stirrers that exhibit chaotic advection.

Electromagnetic fields at work places experts of the cellular companies

10.12737/5019 ◽  
2014 ◽  
Vol 8 (1) ◽  
pp. 1-4
Author(s):  
Горохов ◽  
E. Gorokhov ◽  
Ляпкало ◽  
A. Lyapkalo
Keyword(s):  
Magnetic Fields ◽  
Electromagnetic Radiation ◽  
Electromagnetic Fields ◽  
Electric Fields ◽  
Working Conditions ◽  
Base Stations ◽  
Frequency Range ◽  
Magnetic Components ◽  
Electronic Computers ◽  
The Impact

The paper presents the results of instrumental studies by means of hygienic assessment of levels of electromagnetic fields (EMF) on the workplaces in cellular companies. Measurements of EFM were made on workplaces of 2 groups of employees during the studies: office administrative specialists and technical employees. Instrumental measurements of EMF levels were made by Personal Electronic Computers (PCs) and receivingtransmitting equipment of base cellular stations (BCS). Measurements of EMF from the PC´s screens based on electric and magnetic components were performed: a tension of electric fields with a frequency range of 5Hz-2 kHz and 2 kHz-4 kHz; a tension of magnetic fields in the frequency range of 5Hz-2 kHz and 2 kHz-4 kHz. Measurements of flux density of electromagnetic energy were performed at operating platforms of base stations and at control operating equipment rooms of cellular stations. There were about 150 workplaces of office administrative specialists with PCs surveyed and more 500 workplaces of technical specialists. The activities of administrations of cellular companies were estimated to ensure the safety of working conditions of employees under the influence of electromagnetic radiation (EMR). Literature data on the impact of EMR on human health and health of employees were presented.

scholarly journals Trichomonas vaginalis and Giardia lamblia Growth Alterations by Low-Frequency Electromagnetic Fields

2019 ◽  
Author(s):  
Abraham Octavio RODRÍGUEZ-DE LA FUENTE ◽  
Ricardo GOMEZ-FLORES ◽  
José Antonio HEREDIA-ROJAS ◽  
Edna Marbella GARCÍA-MUÑOZ ◽  
Javier VARGAS-VILLARREAL ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Electromagnetic Fields ◽  
Giardia Lamblia ◽  
Trichomonas Vaginalis ◽  
Low Frequency ◽  
Antagonistic Effect ◽  
Logarithmic Phase ◽  
Physical Factors ◽  
Field Exposure

Background: There is an increasing interest in using physical factors such as magnetic fields as antimicrobial strategy, with variable results. The current study was aimed to evaluate the influence of extremely low-frequency electromagnetic fields (ELF-EMFs) on the axenically-cultured parasite protozoans Trichomonas vaginalis and Giardia lamblia growth. Methods: Bioassays were developed using T. vaginalis, GT-13 and G. lamblia IMSS-0989 strains cultured at 37 ºC in TYI-S-33 medium. The following treatment regimens and controls were considered: (a) cells exposed to ELF-EMFs, (b) untreated cells, (c) cells treated with Metronidazole, used as positive controls, and (d) cells co-exposed to ELF-EMFs and Metronidazole. When cultures reached the end of logarithmic phase, they were exposed to ELF-EMFs for 72 h, in a standardized magnetic field exposure facility. For determining cytotoxic effects, trophozoite density was blindly evaluated in a Neubauer chamber. Results: A significant decrease in trophozoite growth was observed for T. vaginalis, in magnetic field-treated cultures. On the other hand, cultures co-exposed to ELF-EMFs and Metronidazole showed no significant differences when compared with cultures treated with Metronidazole alone. On the contrary, an increased trophozoite density was observed in G. lamblia cultures after exposure to magnetic fields. An absence of a synergistic or antagonistic effect was observed. Conclusion: ELF-EMFs induced T. vaginalis and G. lamblia growth alterations, indicating a potential effect in cell cycle progression.

Sensing of Local, Highly Concentrated Magnetic Field Gradients in Magnetotactic Bacteria Induces Motility Reversal

2012 ◽  
Author(s):  
Lina M. González ◽  
Warren C. Ruder ◽  
William C. Messner ◽  
Philip R. LeDuc
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetotactic Bacteria ◽  
Chemical Gradients ◽  
Field Gradients ◽  
Magnetic Field Gradients ◽  
Direction Of Movement ◽  
Unicellular Organisms ◽  
Sense And Respond ◽  
Direction Reversal

Many motile unicellular organisms have evolved specialized behaviors for detecting and responding to chemical gradients (chemotaxis) or oxygen (aerotaxis), while magnetotactic bacteria sense magnetic fields to align their direction of movement. Herein we show that Magnetospirillum magneticum (AMB-1) have the ability to sense and respond not only to the direction of magnetic fields of naturally occurring magnitude, but also to local, highly concentrated magnetic field gradients that do not occur in their natural environment. We imposed these gradients through our system integrating Helmholtz coils and permalloy (Ni80Fe20) microstructures. The AMB-1 exhibit three distinct behaviors as they approached gradients near the microstructures—unidirectional, single direction reversal, and double direction reversal. These results indicate previously unknown capabilities of the magnetic sensing systems of AMB-1.

scholarly journals Anisotropic cosmological solutions to the Y(R)F2 gravity

2019 ◽  
Vol 34 (35) ◽  
pp. 1950286 ◽  
Author(s):  
Özcan Sert ◽  
Muzaffer Adak
Keyword(s):  
Variational Principle ◽  
Magnetic Fields ◽  
Electromagnetic Fields ◽  
Electric Fields ◽  
Isotropic Case ◽  
Field Equations ◽  
Cosmological Solutions

We investigate anisotropic cosmological solutions of the theory with non-minimal couplings between electromagnetic fields and gravity in [Formula: see text] form. After we derive the field equations by the variational principle, we look for spatially flat cosmological solutions with magnetic fields or electric fields. Then, we give exact anisotropic solutions by assuming the hyperbolic expansion functions. We observe that the solutions approach the isotropic case in late-times.

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