Numerical Study on an Equivalent Source Model for Inhomogeneous Magnetic Field Dosimetry in the Low-Frequency Range

2004 ◽  
Vol 51 (4) ◽  
pp. 612-616 ◽  
Author(s):  
S. Nishizawa ◽  
H.-O. Ruo ◽  
F.M. Landstorfer ◽  
O. Hashimoto
Keyword(s):  
Magnetic Field ◽  
Numerical Study ◽  
Low Frequency ◽  
Source Model ◽  
Inhomogeneous Magnetic Field ◽  
Frequency Range ◽  
Equivalent Source

scholarly journals A broadband two axis flux-gate magnetometer

1998 ◽  
Vol 41 (3) ◽  
Author(s):  
P. Palangio
Keyword(s):  
Magnetic Field ◽  
Low Frequency ◽  
High Sensitivity ◽  
Magnetic Sensors ◽  
Frequency Range ◽  
Field Station ◽  
Low Weight ◽  
Highly Sensitive ◽  
Flux Gate ◽  
Magnetic Field Variations

A broadband two axis flux-gate magnetometer was developed to obtain high sensitivity in magnetotelluric measurements. In magnetotelluric sounding, natural low frequency electromagnetic fields are used to estimate the conductivity of the Earth's interior. Because variations in the natural magnetic field have small amplitude(10-100 pT) in the frequency range 1 Hz to 100 Hz, highly sensitive magnetic sensors are required. In magnetotelluric measurements two long and heavy solenoids, which must be installed, in the field station, perpendicular to each other (north-south and east-west) and levelled in the horizontal plane are used. The coil is a critical component in magnetotelluric measurements because very slight motions create noise voltages, particularly troublesome in wooded areas; generally the installation takes place in a shallow trench. Moreover the coil records the derivative of the variations rather than the magnetic field variations, consequently the transfer function (amplitude and phase) of this sensor is not constant throughout the frequency range 0.001-100 Hz. The instrument, developed at L'Aquila Geomagnetic Observatory, has a flat response in both amplitude and phase in the frequency band DC-100 Hz, in addition it has low weight, low power, small volume and it is easier to install in the field than induction magnetometers. The sensivity of this magnetometer is 10 pT rms.

scholarly journals Numerical study of magnetic particles mixing in waste water under an external magnetic field

2020 ◽  
Vol 69 (3) ◽  
pp. 266-275 ◽  
Author(s):  
Christos Liosis ◽  
Evangelos G. Karvelas ◽  
Theodoros Karakasidis ◽  
Ioannis E. Sarris
Keyword(s):  
Magnetic Field ◽  
Magnetic Particles ◽  
Numerical Study ◽  
Low Frequency ◽  
Water And Wastewater Treatment ◽  
Novel Approach ◽  
Optimal Value ◽  
Frequency Optimum ◽  
Combined Action ◽  
Aligned Magnetic Field

Abstract The combination of nanotechnology and microfluidics may offer an effective water and wastewater treatment. A novel approach combines the use of magnetic particles which can capture heavy metal impurities in microfluidic ducts. The purpose of this study is to investigate the mixing mechanism of two water streams, one with magnetic particles and the other with wastewater. The optimum mixing is obtained when particles are uniformly distributed along the volume of water in the duct for the combined action of a permanent, spatially and temporally aligned magnetic field. Results showed that mixing is enhanced as the frequency of the magnetic field decreases or its amplitude increases, while magnetic gradient is found to play an insignificant role in the present configuration. Moreover, for simulations with low frequency, the mean concentration of particles is found to be twice as high as compared to the cases with higher frequency. Optimum distribution of particles inside the micromixer is observed for the combination of 0.6 T, 8 T/m and 5 Hz for the magnetic magnitude, gradient and frequency, respectively, where concentration reaches the optimal value of 0.77 mg/mL along the volume of the duct.

scholarly journals System for detection of the inhomogeneous distribution of magnetic field based on liquid crystals with magnetic nanoparticle

2021 ◽  
Vol 4 (2) ◽  
Keyword(s):  
Magnetic Field ◽  
Liquid Crystals ◽  
Magnetic Nanoparticles ◽  
Low Frequency ◽  
Inhomogeneous Magnetic Field ◽  
Inhomogeneous Distribution ◽  
Frequency Magnetic Field ◽  
Reorientation Time ◽  
Main Component ◽  
To Receive

The main objective of this article is to develop the basic technological principles of production of the magnetosensitive layer based on nematic liquid crystals with magnetic nanoparticles as the main component of the system, which allows obtaining a two-dimensional picture of the inhomogeneous distribution of low-frequency magnetic field and to identify the object creating this field. In work are described physical methods which allow to increase sensitivity and to expand a working frequency range of the magneto-sensitive layer based on such liquid crystals. By us it has been shown, that the time of reorientation of director in oriented liquid crystals with magnetic nanoparticles is less than the analogous reorientation time in nonoriented crystals. In work also it is shown, that to significantly increase the speed of reorientation in a magnetic field of the director of liquid crystals with magnetic nanoparticles is possible if submitting an additional magnetic field with given amplitude. This method allows to increase sensitivity to a magnetic field and to receive parametrical amplification of signals in liquid crystals with magnetic nanoparticles. In the conclusion on the basis of liquid crystals with magnetic nanoparticles the scheme of system of detection of inhomogeneous magnetic field is described.

Study of Energy Methods to Strongly Nonlinear Vibrations in a Loudspeaker Cone-Shaped Shell

2005 ◽  
Author(s):  
F. D. Zong ◽  
Z. L. Zhang ◽  
J. W. Fang ◽  
Y. J. Yu ◽  
Q. Chen
Keyword(s):  
Magnetic Field ◽  
Limit Cycles ◽  
Nonlinear Oscillations ◽  
Low Frequency ◽  
Approximate Solutions ◽  
Energy Methods ◽  
Frequency Range ◽  
Strongly Nonlinear ◽  
Harmonic Vibrations ◽  
Strongly Nonlinear Oscillations

H. F. Olson points out that a loudspeaker cone-shaped shell, as a nonlinear oscillation system, can be described as the Classical Duffing Equation in low frequency range. Yoshinisa, a Japanese scholar, studied the nonlinear phenomena of the loudspeaker cone-shaped shell in low frequency range driven by a stable galvanic source, including the resonance frequency changing with amplitude and leap phenomena. But their research were not taken the influence of nonlinear magnetic field into account. Its work mostly related to getting solution of nonlinear differential equation by the Numerical Calculation, but it didn’t get approximate solutions. Through research and analysis of the experiment on the loudspeaker cone-shaped shell, we obtain the Generalized Duffing Equation that’s a strongly nonlinearity system which is used to describe the loudspeaker cone-shaped shell driven by a stable voltage source, it considers the nonlinearity of mechanical resilience and the magnetic field. This paper focuses on first finding the approximate solutions (limit cycles) of strongly nonlinear oscillations and nonlinear heteronomy of the loudspeaker cone-shaped shell in low frequency range by use of energy methods. They obtained the equation relating to the forced vibration amplitude with frequency and the corresponding relation about phase versus frequency, and analysed particularly complete stability of limit cycles belonged to the strongly nonlinear systems, and drew several important conclusions. (1) As to strongly nonlinear oscillations of the loudspeaker cone-shaped shell in low frequency range, it is only likely to appear main oscillation and odd-order sub-harmonic oscillations. But it cannot appear super-harmonic vibrations and even-order sub-harmonic vibrations. (2) As to strongly nonlinear oscillations of the loudspeaker cone-shaped shell in low frequency range, two cases about main oscillation and one third sub-harmonic oscillation whose approximate solutions accord with numerical solutions very well. (3) It is worthy to study strongly nonlinear oscillations of commonly thin shell structure such as a loudspeaker cone-shaped shell by use of energy methods, and we will continue to carry out this research.

Equivalent Source Model for Electrical Appliances emitting low Frequency Magnetic Fields

2001 ◽  
Author(s):  
Shinichiro Nishizawa ◽  
Wolfgang Spreitzer ◽  
Hans-Oliver RuoB ◽  
F.M Landstorfer ◽  
Osamu Hashimoto
Keyword(s):  
Magnetic Fields ◽  
Low Frequency ◽  
Source Model ◽  
Equivalent Source

Effect of probe geometry on the Hall response in an inhomogeneous magnetic field: A numerical study

1998 ◽  
Vol 83 (11) ◽  
pp. 6161-6165 ◽  
Author(s):  
S. Liu ◽  
H. Guillou ◽  
A. D. Kent ◽  
G. W. Stupian ◽  
M. S. Leung
Keyword(s):  
Magnetic Field ◽  
Numerical Study ◽  
Inhomogeneous Magnetic Field ◽  
Probe Geometry

THE INFLUENCE OF THE IONOSPHERE ON THE VERTICAL FORCE EXCITED BY A HORIZONTAL ELECTRIC DIPOLE

2020 ◽  
pp. 68-76
Author(s):  
P. E. Tereshchenko
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Vertical Component ◽  
Low Frequency ◽  
Vertical Force ◽  
Frequency Range ◽  
The Earth ◽  
Horizontal Electric Dipole ◽  
Lower Frequency Range ◽  
The Magnetic Field

An analytical expression for the vertical component of the magnetic field has been obtained, with the help of which calculations have been made showing the effect of the ionosphere on the low-frequency field in the Earth-ionosphere waveguide. At distances from the source that are less than the doubled waveguide height, in ELF, and a lower frequency range, noticeable changes in the field strength caused by the state of the ionosphere are found.

scholarly journals Магнитно-резонансная силовая спектроскопия колебаний магнитного вихря

2020 ◽  
Vol 90 (11) ◽  
pp. 1821
Author(s):  
В.Л. Миронов ◽  
Е.В. Скороходов ◽  
Д.А. Татарский ◽  
И.Ю. Пашенькин
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Longitudinal Magnetic Field ◽  
Low Frequency ◽  
Inhomogeneous Magnetic Field ◽  
Magnetic Vortex ◽  
Significant Shift ◽  
Main Attention ◽  
Micromagnetic Modeling ◽  
Spectroscopy Studies

We present the results of micromagnetic modeling and experimental magnetic resonance force spectroscopy studies of forced magnetization oscillations in a circle NiFe disk in an external longitudinal magnetic field. The main attention is paid to the low-frequency resonance associated with the gyrotropic motion of the magnetic vortex core. It is shown that the applying external magnetic field in the plane of the sample leads to a significant shift in the resonance frequency of the gyrotropic mode. The influence of the inhomogeneous magnetic field of the probe on the peculiarities of the magnetization oscillations is discussed.

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