Production of magnetic flux A rotating magnetic field in the stator is the first part of operation. To produce a torque and thus rotate‚ the rotors must be carrying some current. In induction motors‚ this current comes from the rotor conductors. The revolving magnetic field produced in the stator cuts across the conductive bars of the rotor and induces an e.m.f. The rotor windings in an induction motor are either closed through an external resistance or directly shorted. Therefore‚ the e.m.f induced
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a rather low intensity magnetic field. Alnico magnet alloy is now mainly used in applications where the magnet will be exposed to elevated temperatures. • Rare Earth Magnets Samarium Cobalt (SmCo) and Neodymium Iron Boron (NdFeB) are called Rare Earth because Neodymium and Samarium are found in the rare earth elements on the periodic table. Both Samarium Cobalt and Neodymium magnet alloys are powdered metals which are compacted in the presence of a strong magnetic field and are then sintered.
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Temperature Limitation EMI* Resistance Mechanical Durability Coil and Magnet Velocity Sensor Piezoelectric Velocity Sensor Yes No Yes Yes Acceptable Excellent No Good Sensor Dependent > +707°F (+375°C) Acceptable Good Yes Good Yes +248°F (+120°C) Excellent Excellent *EMI–Electro Magnetic Interference Traditional velocity sensors are of a mechanical design that uses an electromagnetic (coil and magnet) system to generate the velocity signal. Recently‚ hardier
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HISTROY The evolution of active magnetic bearings may be traced through the patent issued in this field. Earlier patents for magnetic suspensions can be found but are excluded here because they consist of assemblies of permanent magnets of problematic stability per Earns haw’s Theorem. Early active magnetic bearing patents were assigned to Jesse beams at the university of Virginia during World War II and are concerned with ultracentrifuges for purification of the isotopes of various elements for
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Chapter 4‚ page 1 4 Nuclear Magnetic Resonance Pieter Zeeman observed in 1896 the splitting of optical spectral lines in the field of an electromagnet. Since then‚ the splitting of energy levels proportional to an external magnetic field has been called the "Zeeman effect". The "Zeeman resonance effect" causes magnetic resonances which are classified under radio frequency spectroscopy (rf spectroscopy). In these resonances‚ the transitions between two branches of a single energy level
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Magnetic tape is a medium for magnetic recording‚ made of a thin magnetizable coating on a long‚ narrow strip of plastic film. It was developed in Germany‚ based on magnetic wire recording. Devices that record and play back audio and video using magnetic tape are tape recorders and video tape recorders. A device that stores computer data on magnetic tape is a tape drivOver years‚ magnetic tape can suffer from deterioration called sticky-shed syndrome. Caused by absorption of moisture into the binder
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Magnetic ink is very useful because it is readable both by humans and by specialized equipment. It is one of the components that makes it possible to process personal checks securely‚ quickly and accurately. Magnetic ink character recognition (MICR) is a character-recognition technology used mainly by the banking industry to ease the processing and clearance of cheques and other documents. The MICR encoding‚ called the MICR line‚ is at the bottom of cheques and other vouchers and typically includes
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Design‚ Construction‚ and Testing of an Inductive Pulsed-Power Supply for a Small Railgun A. Sitzman‚ D. Surls‚ and J. Mallick Institute for Advanced Technology‚ The University of Texas at Austin Abstract—Advances in high-power-density batteries have rekindled interest in using inductive store as a pulse compression system. Although these batteries are considered very power dense‚ they lack over an order of magnitude of power density to drive a deployable electric gun. However‚ one can add
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INTRODUCTION: Magnetic Resonance Imaging(MRI) is a non invasive medical imaging method widely used in hospitals and in research. In year 1946 Felix Bloch of Standard /university and Edward Purcell of Harvard University made the first succesful nuclear magnetic resonance experiment to study chemical compounds‚ they were awarded the Nobel Prize for physics in 1952. In early 1980 ’s the first human magnetic resonance imaging( MRI) scanners became available‚ producing images of the inside of the
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Journal of Magnetism and Magnetic Materials 324 (2012) 3351–3355 Contents lists available at SciVerse ScienceDirect Journal of Magnetism and Magnetic Materials journal homepage: www.elsevier.com/locate/jmmm Investigation of magnetocaloric effect in La0.45Pr0.25Ca0.3MnO3 by magnetic‚ differential scanning calorimetry and thermal analysis M. Aparnadevi‚ S.K. Barik‚ R. Mahendiran n Department of Physics‚ 2 Science Drive 3‚ National University of Singapore‚ Lower Kent Ridge Road‚ Singapore-117
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