Earth's Solid Iron Core May Skew Its Magnetic Field

The direct coil cooling method is one of the existing cooling techniques for electric machines with concentrated windings, in which cooling tubes of conductive material are inserted between the windings. In such cases, eddy current losses are induced in those cooling tubes because of the time variant magnetic field. To compute the cooling tubes losses, either a transient finite element simulation (mostly based on commercial software), or a full analytical method, which is more complex to be constructed, is required. Instead, this paper proposes a simple and an accurate combined semi-analytical-finite element method to calculate the losses of electric machines having cooling tubes. The 2D magnetostatic solution of the magnetic field is obtained e.g., using the free package “FEMM”. Then, the eddy current losses in the tubes are computed using simple analytical equations. In addition, the iron core losses could be obtained. In order to validate the proposed method, two cases are investigated. In Case 1, a six-toothed stator of a switched reluctance machine (SRM), without rotor, is employed in which six cooling tubes are used while in Case 2 a complete rotating SRM is studied. The proposed method is validated by a 2D transient simulation in the commercial software “ANSYS Maxwell” and also by experimental measurements. Evidently, the proposed method is simple and fast to be constructed and it is almost free of cost.

Download Full-text

Quadruple Fortification of Salt with Iodine, Iron, Vitamins B9 and B12 to Reduce Maternal and Neonatal Mortality by Reducing Anemia and Nutritional Deficiency Prevalence (P24-041-19)

Current Developments in Nutrition ◽

10.1093/cdn/nzz044.p24-041-19 ◽

2019 ◽

Vol 3 (Supplement_1) ◽

Author(s):

Venkatesh Mannar ◽

Levente Diosady

Keyword(s):

Folic Acid ◽

Vitamin B12 ◽

Pilot Scale ◽

Iron Core ◽

Ferrous Fumarate ◽

Funding Sources ◽

Spray Solution ◽

Solid Iron ◽

Gates Foundation ◽

Average Size

Abstract Objectives To develop a quadruple fortified salt(QFS) formulation that provides100 + % of RDA for iodine and vitamin B12 and 30–50% of RDA for iron and folic acid in forms that are organoleptically stable, bioavailable and acceptable to consumers Methods Iodine was sprayed onto salt as an aqueous solution of potassium iodate. Iron was admixed as a solid premix, which was colour masked with TiO2 and encapsulated in soy stearine to provide a water-impervious coating. The iron core was made of ferrous fumarate, which was agglomerated to an average size matching salt grain, i.e., 300–500 µm. Folic acid and vitamin B12 were added either in the iodate spray solution or in the solid iron premix. The premixes and salt were stored at 25, 35 and 45°C at 65% RH for up to a year. The loss of iodine, folic acid and vitamin B12 were monitored. An optimized formulation was tested on the pilot scale at JVS Foods Pvt, Jaipur, India. Results Folic acid can be stabilized in the iodine spray solution, and triple fortified salt containing iodine, folic acid and encapsulated ferrous fumarate retained >90% of both the added iodine and folic acid for 6 months. Stable QFS was made by incorporating vitamin B12 in the solid iron premix at a 1:200 ratio. The process was scaled up to produce some 25 kg of iron and B12premix, sufficient for 5 tons of salt, or 500,000 daily doses of salt. Organoleptic testing of Indian meals produced with quadruple fortified salt were found to be acceptable by a consumer panel at the University of Delhi. Conclusions Stable quadruple fortified salt that can provide up to 50% of RDA of folic acid and iron and 100 + % of RDA of vitamin B12 and iodine has been developed. The product was pilot tested and had high consumer acceptability. The formulation could reduce the incidence of maternal and infant mortality at a cost of less than 20¢/annum. Funding Sources This research was funded by Grand Challenges Canada through the Saving Lives at Birth program, and by the Bill and Melinda Gates Foundation.

Download Full-text

Magnetorotational supernovae with different equations of state

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312013336 ◽

2011 ◽

Vol 7 (S279) ◽

pp. 357-358

Author(s):

Sergey G. Moiseenko ◽

Gennady S. Bisnovatyi-Kogan

Keyword(s):

Magnetic Field ◽

Shock Wave ◽

Angular Momentum ◽

Differential Rotation ◽

Equations Of State ◽

Supernova Explosion ◽

Explosion Energy ◽

Iron Core ◽

Wave Forms ◽

The Magnetic Field

AbstractWe present results of the simulation of a magneto-rotational supernova explosion. We show that, due to the differential rotation of the collapsing iron core, the magnetic field increases with time. The magnetic field transfers angular momentum and a MHD shock wave forms. This shock wave produces the supernova explosion. The explosion energy computed in our simulations is 0.5-2.5 ċ 1051erg. We used two different equations of state for the simulations. The results are rather similar.

Download Full-text

Planetary Magnetic Fields and Dynamos

Oxford Research Encyclopedia of Planetary Science ◽

10.1093/acrefore/9780190647926.013.31 ◽

2019 ◽

Cited By ~ 3

Author(s):

Ulrich R. Christensen

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Field Strength ◽

Thermal Evolution ◽

Rotation Axis ◽

Space Environment ◽

Conducting Layer ◽

Iron Core ◽

Complex Flow ◽

Dynamo Theory

Since 1973 space missions carrying vector magnetometers have shown that most, but not all, solar system planets have a global magnetic field of internal origin. They have also revealed a surprising diversity in terms of field strength and morphology. While Jupiter’s field, like that of Earth, is dominated by a dipole moderately tilted relative to the planet’s spin axis, the fields of Uranus and Neptune are multipole-dominated, whereas those of Saturn and Mercury are highly symmetric relative to the rotation axis. Planetary magnetism originates from a dynamo process, which requires a fluid and electrically conducting region in the interior with sufficiently rapid and complex flow. The magnetic fields are of interest for three reasons: (i) they provide ground truth for dynamo theory, (ii) the magnetic field controls how the planet interacts with its space environment, for example, the solar wind, and (iii) the existence or nonexistence and the properties of the field enable us to draw inferences on the constitution, dynamics, and thermal evolution of the planet’s interior. Numerical simulations of the geodynamo, in which convective flow in a rapidly rotating spherical shell representing the outer liquid iron core of the Earth leads to induction of electric currents, have successfully reproduced many observed properties of the geomagnetic field. They have also provided guidelines on the factors controlling magnetic field strength and morphology. For numerical reasons the simulations must employ viscosities far greater than those inside planets and it is debatable whether they capture the correct physics of planetary dynamo processes. Nonetheless, such models have been adapted to test concepts for explaining magnetic field properties of other planets. For example, they show that a stable stratified conducting layer above the dynamo region is a plausible cause for the strongly axisymmetric magnetic fields of Mercury or Saturn.

Download Full-text

Magnetic Field Analysis of a Complex Construction Transformer Using Direct Field-Circuit Coupling Method

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.614-615.1230 ◽

2012 ◽

Vol 614-615 ◽

pp. 1230-1233

Author(s):

Yan Li Zhang ◽

Ning Zhang ◽

Ya Hua Kang ◽

Xiu Ke Yan ◽

De Xin Xie

Keyword(s):

Magnetic Field ◽

Field Distribution ◽

Magnetic Field Distribution ◽

Field Analysis ◽

Main Magnetic Field ◽

Iron Core ◽

Special Configuration ◽

Magnetic Field Analysis ◽

Calculation Results ◽

Transport Condition

This paper deals with the main magnetic field distribution for a three-phase five-column disintegration transformer with the iron core disassembled into several parts owing to limited transport condition. The finite element method is employed to solve such a special configuration transformer, in which the direct field-circuit coupling formulation is derived and programmed by APDL programming language. The calculation results, such as the magnetic field distribution in transformer core, the exciting current magnitude and no-load loss are investigated. The optimum size of air gap between each separated iron core limbs is discussed.

Download Full-text