Oscillatory Flow of a Magnetic Fluid in a Pipe at Low Frequency Range Under a Magnetic Field: Phase Difference of Pressure

2003 ◽  
Author(s):  
Kunio Shimada ◽  
Shigemitsu Shuchi ◽  
Shinichi Kamiyama
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
Phase Difference ◽  
Mass Concentration ◽  
Oscillatory Flow ◽  
Low Frequency ◽  
Nonuniform Distribution ◽  
Straight Pipe ◽  
Number Range ◽  
Steady Magnetic Field

We made on numerical analysis of phase difference between pressure along the pipe axis and given oscillatory flow velocity in an straight pipe under a nonuniform steady magnetic field. In the analysis, a few cases under the assumption of numerical condition were conducted on: the first is taking into account the least compressibility of the fluid with using the obtained experimental data of the bulk modulus, the second taking into account the nonuniform distribution of mass concentration of particles, and the thrid taking into account the aggregation with the number of aggregated particles proposing as a prorate spheroid. By considering the three effects of the least compressibility and the nonuniform distribution of mass concentration, the aggregation as a prorate spheroid, the phase difference varies quantitatively at the lowest Womersley number range. And then, the numerical results were compared with the experimental data.

ANALYTIC RELATION BETWEEN THE PEAK TEMPERATURE OF THE IMAGINARY PART OF THE ac SUSCEPTIBILITY OF A SUPERCONDUCTOR AND THE APPLIED dc MAGNETIC FIELD

1992 ◽  
Vol 06 (06) ◽  
pp. 335-341
Author(s):  
ZENG XINGLIN ◽  
CAO LIEZHAO ◽  
ZHANG YUHENG
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
Theoretical Prediction ◽  
Power Law ◽  
Ac Susceptibility ◽  
Low Frequency ◽  
Field Amplitude ◽  
Peak Temperature ◽  
Analytic Relation ◽  
Dc Magnetic Field

The critical state model is employed to calculate the real (χ′) and imaginary parts (χ″) of ac susceptibility of a homogeneous superconducting slab (or a cylinder) under the conditions of ac magnetic field amplitude H ac ≪H dc (superimposed dc magnetic field) and low frequency. The calculated results are analytic and a relation (4π/c)J c (T p , H dc )d= (3/4) H ac between the χ″-peak temperature (T p ) and H dc is obtained. The theoretical prediction for χ′-χ″ curve is consistent with our experimental data, and the experimental power law [Formula: see text] in high-T c superconductors was explained using the above relation.

scholarly journals Frequency-induced negative magnetic susceptibility in epoxy/magnetite nanocomposites

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Che-Hao Chang ◽  
Shih-Chieh Su ◽  
Tsun-Hsu Chang ◽  
Ching-Ray Chang
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
Electromagnetic Field ◽  
Magnetic Susceptibility ◽  
Memory Effect ◽  
Low Frequency ◽  
Magnetization Vector ◽  
Microwave Frequency ◽  
Debye Relaxation ◽  
X Band

AbstractThe epoxy/magnetite nanocomposites express superparamagnetism under a static or low-frequency electromagnetic field. At the microwave frequency, said the X-band, the nanocomposites reveal an unexpected diamagnetism. To explain the intriguing phenomenon, we revisit the Debye relaxation law with the memory effect. The magnetization vector of the magnetite is unable to synchronize with the rapidly changing magnetic field, and it contributes to diamagnetism, a negative magnetic susceptibility for nanoparticles. The model just developed and the fitting result can not only be used to explain the experimental data in the X-band but also can be used to estimate the transition frequency between paramagnetism and diamagnetism.

scholarly journals Study of the effect of low-frequency magnetic fields on biological objects

2011 ◽  
Vol 16 (4) ◽  
pp. 144-148
Author(s):  
M.M. Baran ◽  
R.V. Bubnov ◽  
T.O. Vojcekhovskaya ◽  
L.S. Gnatyuk ◽  
V.I. Zubchuk ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
Magnetic Fields ◽  
Low Frequency ◽  
Ph Changes ◽  
Biological Objects ◽  
Water Ph ◽  
Environment Parameters ◽  
The Magnetic Field

One of the possible approaches on modeling of the magnetotherapeutic effects on biological objects is considered, using water as an example. Experimental data of the water pH changes depending on the effect of the magnetic field and the environment parameters are

Response Sensitivity of Faraday Magneto-Optical Effects of Ferrofluid

2010 ◽  
Vol 663-665 ◽  
pp. 1221-1224 ◽  
Author(s):  
Shi Bin Wang ◽  
Cheng Bo Yu ◽  
Lin Du ◽  
Cai Xin Sun ◽  
Jia Yang
Keyword(s):  
Magnetic Field ◽  
Mass Concentration ◽  
Modulation Depth ◽  
Polarized Light ◽  
Low Frequency ◽  
Magnetic Domain ◽  
Optical Transmittance ◽  
Mean Value ◽  
Field Frequency ◽  
Frequency Properties

The transmitted intensity and the modulation depth of plane polarized light are implemented to investigate influences of the low frequency external magnetic field on the ferrofluid film. The frequency of AC magnetic field is modulated from 5Hz to 400Hz, and the thickness of ferrofluid films are changed as 12 μm, 25 μm, 140 μm and 520 μm, and the mass concentration of magnetic nanoparticles is 5 %, 10 %, 20 % and 33.6 %, respectively. The experimental results show that (1) the mean value of the optical transmittance of ferrofluid film is decided by the thickness of ferrofluid film and the mass concentration of nanoparticles, but the frequency of magnetic field has no direct relation with it; (2) under a given magnetic field intensity, the optical modulation depth of ferrofluid film is determined by the film thickness, the nanoparticle concentration and the magnetic field frequency. It is further found that the single relaxation characteristics of magnetic nanoparticle, whose size is smaller than the critical value of the single magnetic domain, is the important factor of the frequency properties of nanoparticle in ferrofluid. These results may be beneficial to applications of ferrofluid in magneto-optic sensors.

scholarly journals Penetration of magnetic field into superconductors. II. Measurements by the Casimir method

1949 ◽  
Vol 198 (1055) ◽  
pp. 560-581 ◽  
Keyword(s):  
Magnetic Field ◽  
Transition Temperature ◽  
Principal Axis ◽  
Current Flow ◽  
Low Frequency ◽  
Mutual Inductance ◽  
Surface Conditions ◽  
Significant Difference ◽  
Steady Magnetic Field ◽  
Experimental Errors

The changes with temperature of penetration of a magnetic field into superconducting tin and mercury were studied by a method due to Casimir in which a mutual inductance with a superconducting core is measured using low-frequency currents. The results were found to be very sensitive to surface conditions, but single crystals with smooth surfaces gave reproducible measurements of λ(T) — λ (2.17° K) as a function of temperature T . These were consistent with the formula λ(T) = λ 0 (1—( T/T c ) 4 ) -½ , where T c is the transition temperature, and λ 0 was found to be 5.2 x 10 -6 cm. for tin and 4.3 x 10 -6 cm. for mercury. For tin there was no significant difference between the values of λ 0 for current flow in different crystal directions, though a difference of up to 20% is not excluded. For mercury there is a suggestion that λ 0 is about 20% higher for current flow perpendicular to the principal axis than it is for current flow parallel to the principal axis, but this difference is little more than might be due to experimental errors. There was no evidence for any dependence of λ on a steady magnetic field H , though an increase of 10% up to 80% of the critical field is not excluded.

scholarly journals Propagation of low frequency geomagnetic field fluctuations in Antarctica: comparison between two polar cap stations

2007 ◽  
Vol 25 (11) ◽  
pp. 2405-2412 ◽  
Author(s):  
L. Santarelli ◽  
S. Lepidi ◽  
L. Cafarella
Keyword(s):  
Magnetic Field ◽  
Interplanetary Magnetic Field ◽  
Phase Difference ◽  
Low Frequency ◽  
Propagation Direction ◽  
Field Conditions ◽  
Polar Cap ◽  
Night Time ◽  
Substorm Activity ◽  
A Minor

Abstract. We conduct a statistical analysis of the coherence and phase difference of low frequency geomagnetic fluctuations between two Antarctic stations, Mario Zucchelli Station (geographic coordinates: 74.7° S, 164.1° E; corrected geomagnetic coordinates: 80.0° S, 307.7° E) and Scott Base (geographic coordinates: 77.8° S 166.8° E; corrected geomagnetic coordinates: 80.0° S 326.5° E), both located in the polar cap. Due to the relative position of the stations, whose displacement is essentially along a geomagnetic parallel, the phase difference analysis allows to determine the direction of azimuthal propagation of geomagnetic fluctuations. The results show that coherent fluctuations are essentially detectable around local geomagnetic midnight and, in a minor extent, around noon; moreover, the phase difference reverses in the night time hours, indicating a propagation direction away from midnight, and also around local geomagnetic noon, indicating a propagation direction away from the subsolar point. The nigh time phase reversal is more clear for southward interplanetary magnetic field conditions, suggesting a relation with substorm activity. The introduction, in this analysis, of the Interplanetary Magnetic Field conditions, gave interesting results, indicating a relation with substorm activity during nighttime hours. We also conducted a study of three individual pulsation events in order to find a correspondence with the statistical behaviour. In particular, a peculiar event, characterized by quiet magnetospheric and northward interplanetary magnetic field conditions, shows a clear example of waves propagating away from the local geomagnetic noon; two more events, occurring during southward interplanetary magnetic field conditions, in one case even during a moderate storm, show waves propagating away from the local geomagnetic midnight.

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