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Magnetic Induction (magnetic + induction)

Distribution by Scientific Domains

Physics and Astronomy	44%

Selected Abstracts

Interference of 16.7-Hz electromagnetic fields on measured electrocardiogram

BIOELECTROMAGNETICS, Issue 5 2007
Christoph J. Schlimp
Abstract The extent of electromagnetic interference (EMI) from 16.7-Hz alternate current power lines in the human surface electrocardiogram (ECG) was evaluated. Results showed a direct linear correlation between mean EMI and magnetic induction of 5.8,21 µT on a railroad platform (electric field: 270 V/m). EMI inside a railroad car (10 µT, 0 V/m) was comparable to the electromagnetic field at the platform. Inside a voltage transformer substation (0 µT, 2000 V/m) EMI occurred only when the ECG device was closer to the power line than the test person. Magnetic induction caused 16.7-Hz EMI to a degree that proper diagnosis of ECG-rhythms was rendered impossible. Bioelectromagnetics 28:402,405, 2007. © 2007 Wiley-Liss, Inc. [source]

Leakage field distribution of a transformer for conventional and superconducting conditions

EUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 4 2002
P. Raitsios
The overall distribution of leakage field and current density in a transformer model with cylindrical windings in proximity to the core yokes is investigated from a different viewpoint than that of Kapp or Rogowski, i.e. by taking into consideration the conductivity of the conductive material. Using Maxwell's differential equations and the vector potential and by considering the conductivity of the conductive material, general equations are obtained for the components of the magnetic induction in a two dimensional space. From these components the leakage inductance is calculated and its application for conventional and superconducting conditions is examined. The distribution of current density in the windings is obtained from the vector potential. [source]

Temperature-Sensitive Nanocapsules for Controlled Drug Release Caused by Magnetically Triggered Structural Disruption

ADVANCED FUNCTIONAL MATERIALS, Issue 4 2009
Ting-Yu Liu
Abstract Self-assembled nanocapsules containing a hydrophilic core and a crosslinked yet thermosensitive shell are successfully prepared using poly(ethylene-oxide)-poly(propylene-oxide)-poly(ethylene-oxide) block copolymers, 4-nitrophenyl chloroformate, gelatin, and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide. The core is further rendered magnetic by incorporating iron oxide nanoparticles via internal precipitation to enable externally controlled actuation under magnetic induction. The spherical nanocapsules exhibit a hydrophilic-to-hydrophobic transition at a characteristic but tunable temperature reaching 40,°C, triggering a size contraction and shrinkage of the core. The core content experiences very little leakage at 25,°C, has a half life about 5,h at 45,°C, but bursts out within a few minutes under magnetic heating due to iron oxide coarsening and core/shell disruption. Such burst-like response may be utilized for controlled drug release as illustrated here using a model drug Vitamin B12. [source]

Physical properties of meteorites,Applications in space missions to asteroids

METEORITICS & PLANETARY SCIENCE, Issue 6 2008
T. KOHOUT
However, more detailed observations indicate that differences exist in composition between asteroids and meteorites resulting in difficulties when searching for meteorite-asteroid match. We show that among other physical parameters the magnetic susceptibility of an asteroid can be determined remotely from the magnetic induction by solar wind using an orbiting spacecraft or directly using the AC coil on the lander, or it can be measured in samples returned to the laboratory. The shape corrected value of the true magnetic susceptibility of an asteroid can be compared to those of meteorites in the existing database, allowing closer match between asteroids and meteorites. The database of physical properties contains over 700 samples and was recently enlarged with measurements of meteorites in European museums using mobile laboratory facility. [source]

Toroidal magnetic fields in type II superconducting neutron stars

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2008
T. Akgün
ABSTRACT We determine constraints on the form of axisymmetric toroidal magnetic fields dictated by hydrostatic balance in a type II superconducting neutron star with a barotropic equation of state. Using Lagrangian perturbation theory, we find the quadrupolar distortions due to such fields for various models of neutron stars with type II superconducting and normal regions. We find that the star becomes prolate and can be sufficiently distorted to display precession with a period of the order of years. We also study the stability of such fields using an energy principle, which allows us to extend the stability criteria established by R. J. Tayler for normal conductors to more general media with magnetic free energy that depends on density and magnetic induction, such as type II superconductors. We also derive the growth rate and instability conditions for a specific instability of type II superconductors, first discussed by P. Muzikar, C. J. Pethick and P. H. Roberts, using a local analysis based on perturbations around a uniform background. [source]

Core loss reduction by laser scribing in grain-oriented 3% Si,Fe under different magnetizing direction

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2004
K. S. Ryu
Abstract To reduce the core loss of grain oriented silicon steel, various metallurgical attempts have been made. The laser scribing reduces the core loss of 3% Si,Fe, because sub-domains induced by scribing produce many active domain walls which reduce the eddy current loss. The profiles of ac hysteresis loop and core loss have been measured for samples oriented parallel and perpendicular to the [001] axis in (110)[001] grains of 3% Si,Fe before and after laser scribing. The observed ac hysteresis loop profiles have been analyzed in terms of domain reorientation under field. For the parallel and perpendicular samples, the reductions of core loss are 5.7% and 30.3% by laser scribing at the magnetic induction 1.3 T and magnetizing frequency 60 Hz. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Core loss depending on magnetizing angle from easy axis in grain-oriented 3% silicon-iron

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2004
K. S. Ryu
Abstract The profiles of ac hysteresis loops have been measured as function of the angle , between H -field and [001] axis in (110)[001] grain oriented 3% silicon-iron. As , increases, for , , 30° the loop changes into a wasp-waisted shape with inflection points. The observed ac hysteresis loop profiles have been analyzed in terms of domain reorientation under field. The core losses in silicon-iron are measured for various magnetizing angles with respect to the easy axis at magnetizing frequency 50 Hz and 60 Hz and at magnetic induction 1.3 T and 1.0 T. At magnetic induction 1.3 T, the core loss increased to near 70° and decreased at magnetizing frequency 60 Hz, but at 50 Hz this trend was different from 60 Hz and the core loss was monotonously increased. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Analyzing digital vector waveforms of 0,3000,Hz magnetic fields for health studies,

BIOELECTROMAGNETICS, Issue 5 2010
Joseph D. Bowman
Abstract To improve the assessment of magnetic field exposures for occupational health studies, the Multiwave® System III (MW3) was developed to capture personal exposures to the three-dimensional magnetic field vector B(t) in the 0,3000,Hz band. To process hundreds of full-shift MW3 measurements from epidemiologic studies, new computer programs were developed to calculate the magnetic field's physical properties and its interaction with biological systems through various mechanisms (magnetic induction, radical pair interactions, ion resonance, etc.). For automated calculations in the frequency domain, the software uses new algorithms that remove artifacts in the magnetic field's Fourier transform due to electronic noise and the person's motion through perturbations in the geomagnetic field from steel objects. These algorithms correctly removed the Fourier transform artifacts in 92% of samples and have improved the accuracy of frequency-dependent metrics by as much as 3300%. The output of the MwBatch software is a matrix of 41 exposure metrics calculated for each 2/15,s sample combined with 8 summary metrics for the person's full-period exposure, giving 294 summary-exposure metrics for each person monitored. In addition, the MwVisualizer software graphically explores the magnetic field's vector trace, its component waveforms, and the metrics over time. The output was validated against spreadsheet calculations with pilot data. This software successfully analyzed full-shift MW3 monitoring with 507 electric utility workers, comprising over 1 million vector waveforms. The software's output can be used to test hypotheses about magnetic field biology and disease with biophysical models and also assess compliance with exposure limits. Bioelectromagnetics 31:391,405, 2010. © 2010 Wiley-Liss, Inc. [source]