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Magnetics, IEEE Transactions on

Issue 4 • Date July 1982

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Displaying Results 1 - 10 of 10
  • [Front cover and table of contents]

    Page(s): 0
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    Freely Available from IEEE
  • Computer simulation of the operation of a magnetic bubble domain propagation circuit modeled after a current-access device

    Page(s): 933 - 940
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    The operation of a bubble-domain straight-line propagation circuit has been simulated successfully. This simulation has been achieved by our approximating the motion of an s = 0 frozen-azimuth bubble placed under a drive fieldH_{Z}(X, Y, T)= -H_{p} cdot cos [2pi(X/R_{X} - n(T)/4)] cdot exp [-(Y/R_{Y})^{2}]. The simulation has been generated from a previously developed numerical scheme to simulate the motion of a bubble, whose domain shape and magnetization structure along its domain wall were variable. The drive field has been modeled after a dual conductor-sheet, current-access propagation structure, which has a bit period RXand a transverse width on the order of2R_{Y}. The entire field contour has been advanced stepwise in the positiveXdirection by an increase of the integern(T), which represents the drive-phase number. The bubble motion has been observed during the first six drive phases to produce operating margin diagrams for drive frequencies of 250 KHz, 796 KHz and 1 MHz. The method of calculation and the results of the simulation are given. View full abstract»

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  • Low cobalt Fe-Co-W semihard magnetic alloys for remanent reed switch applications

    Page(s): 941 - 944
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    Semihard magnetic alloys of Fe-Co-W have been developed for application in remanent reed switches. These alloys are very ductile and can be processed into fine wires. The 78%Fe-12%Co- 10%W alloy shows the magnetic properties: Br= 19.2 kG, Br/B200= 0.95, and Hc= 25 Oe. These magnetic properties are superior to those of the commercially used Remendur (49%Co-48%Fe-3%V) or Nibcolloy (85%Co-12%Fe-3%Nb), and the alloy itself consists of a much less expensive cobalt content than those alloys. This 78%Fe-12%Co-10%W alloy is flattenable into reeds, plateable with contact materials, and sealable in glass vials without losing its magnetic properties. Fe-Co-W alloys are adequate for use in remanent reed switches and present distinct advantages from the aspects of their inexpensiveness and superior characteristics. View full abstract»

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  • Some loss relationships in Mn-Zn ferro ferrites and their response to magnetic disturbance

    Page(s): 944 - 950
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    The loss properties of some rings of manganese zinc ferro ferrites, with varying Fe2+contents, have been measured as a function of flux density, frequency, and temperature. At any frequency or temperature the loss factor[tgdelta/mu]^{hat{B}=0}and the hysteresis coefficientetaBhave a linear relationship for the samples which suggests the presence of an effective friction or viscosity field (or aftereffect field). Extrapolation toeta_{B} = 0results in a positive loss[tgdelta/mu]_{0}. This nonhysteresis loss has a large frequency dependent component which is proportional to temperature and which cannot be accounted for by eddy-current losses in the material. There appears to be, by extrapolation, a large nonhysteresis loss at zero frequency. The variability of[tgdelta/mu]_{hat{B}=0}and ηBis examined. The increases in loss after capacitor discharge demagnetization are found to be much greater than the corresponding increases in permeability. Results of the experiments are discussed in terms of the Néel after effect theory. View full abstract»

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  • Effect of raw material and process conditions on properties of Mn-Zn ferrous ferrites

    Page(s): 950 - 952
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    Studies have been carried out on samples of manganese zinc ferrous ferrites prepared using different types of raw materials and varying process conditions like mixing, calcination, and sintering under controlled atmosphere in production type tunnel kilns. Results are presented to show that by optimization of process conditions it is possible to prepare the following. a) Grade-I ferrites with high purity materials, though processed in different ways. b) Grade-II ferrites can tolerate Silica of 0.5% to 0.6% which is normally found in beneficiated iron ore. View full abstract»

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  • Dynamic circuit and Fourier series methods for moment calculation in electrodynamic repulsive magnetic levitation systems

    Page(s): 953 - 960
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    A general theory of moments for electrodynamic magnetic levitation systems has been developed using double Fourier series and dynamic circuit principles. Both employ Parseval's theorem using either wave constant derivatives or the polar waveconstant principle of the Fourier-Bessel/double Fourier series equivalence. A method for calculating angular derivatives of moments and forces is explained, and for all of these methods comparisons are made with experimental results obtained for single and split rail configurations. Extensions of dynamic circuit theory for tilted nonflat and circular magnets are also explained. View full abstract»

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  • Domain interactions between stacked HI-B SiFe sheets

    Page(s): 961 - 963
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    Attempts to reduce anomalous eddy current losses by means of domain refinement are usually performed on single crystals or polycrystalline single sheets. However, studies on stacked sheets reported in this paper showed that arranging the single sheet into a stack may result in a refinement of large 180 degree domains without additional treatments such as scratching. On the other hand, an example is shown which demonstrates that stacking of scratched sheets may result in a distinct widening of domains previously refined by scratches. It can be concluded that single sheet investigations concerning the ac demagnetized domain patterns are of restricted practical relevance. View full abstract»

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  • Domain structures and stress distributions due to ball-point scratching in 3% Si-Fe single crystals with orientation near

    Page(s): 963 - 969
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    To determine a stress distribution due to ball-point scratching, we have observed, using a scanning electron microscope, domain structures on the top and bottom surfaces at 3% Si-Fe single crystals with orientation near View full abstract»

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  • [Back cover]

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  • Simulation of skew domain wall bowing in SiFe laminations with asymmetric roll orientation

    Page(s): 970 - 980
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    Cyclic motion of 180° domain walls spanning perfect monocrystalline laminations with first-order positive cubic anisotropy (like 3% SiFe) has been simulated using a finite segment technique. Only drive field, eddy field, and surface tension forces on the domain wall were considered. Calculations were made for various crystal orientations over the range between View full abstract»

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Aims & Scope

IEEE Transactions on Magnetics publishes research in science and technology related to the basic physics and engineering of magnetism, magnetic materials, applied magnetics, magnetic devices, and magnetic data storage.

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Editor-in-Chief
Pavel Kabos
National Institute of Standards and Technology