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IEEE Transactions on Magnetics

Issue 5 • Date September 1978

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Displaying Results 1 - 25 of 241
  • [Front cover and table of contents]

    Publication Year: 1978, Page(s): 0
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    Freely Available from IEEE
  • Test and evaluation of bubble memories

    Publication Year: 1978, Page(s):300 - 302
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (448 KB)

    Since January, 1977, a test and evaluation program has been conducted at the Jet Propulsion Laboratory to determine the potential usefulness of bubble memories for spacecraft and commercial applications. The memories evaluated were commercially available units which are similar to a NASA-developed memory cell. It is planned to also test other memories as they become available from manufacturers. O... View full abstract»

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  • A comparison of frequency limited bubble device performance and material characteristics

    Publication Year: 1978, Page(s):303 - 305
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (304 KB)

    We have observed the propagation margins as a function of frequency and temperature for a simple half-disk type test circuit fabricated on an (YSmLuCa)3(FeGe)5O12film. We have also measured the temperature dependence of the stripe width, anisotropy field, collapse field, mobility and dynamic coercivity. The frequency dependence of the margin demonstrates that in th... View full abstract»

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  • Bias magnet design for bubble memory devices

    Publication Year: 1978, Page(s):306 - 308
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (272 KB)

    A study has been made of a system consisting of a pair of magnets with thin plates of permeable material on their inner faces. The effect of the plates on the profile of the field between the magnets is predicted as a function of the geometry and the permeability and the way in which the uniformity can be improved is demonstrated.The effect of the permeability is very limited. View full abstract»

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  • Interactions between drive coils and ferrite sheets in bubble memory packages

    Publication Year: 1978, Page(s):309 - 311
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (304 KB)

    Sheets of ferrite or other permeable materials situated very close to drive coils are expected to affect the field distributions within the coils and the inductances of the coils. A theoretical study has been made of a system consisting of a flat rectangular coil with sheets in contact with its flat faces, including the effects of the shapes of the sheets and their permeability and of an angle of ... View full abstract»

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  • Operation of 3µm bubble serial loop devices designed on single level masking

    Publication Year: 1978, Page(s):312 - 314
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (456 KB)

    An all-permalloy single mask level design for a serial loop circuit has been developed and successfully operated using 3 μm bubbles. The design of individual elements for a single level circuit such as generator, replicator and annihilator which were compatible with half-disk propagation patterns was successfully investigated and optimization of permalloy and SiO2spacer film thickn... View full abstract»

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  • An experimental, multilevel, high density disk recording system

    Publication Year: 1978, Page(s):315 - 317
    Cited by:  Papers (16)  |  Patents (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (472 KB)

    Communication technology has been applied to a magnetic disk recording channel to achieve up to a fourfold increase in linear bit density as compared to conventional binary recording. Among the techniques incorporated were digital data transmission by Class IV Partial-Response signaling (Interleaved NRZI), recording channel pre-emphasis, equalization and filtering, and periodic amplitude sampling ... View full abstract»

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  • Magnetic recording at video cassette recorder for home use

    Publication Year: 1978, Page(s):318 - 320
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (288 KB)

    A 2-head helical scan type, home-use video cassette recorder was developed and this new system was named "VHS". The basic tape pattern enables variable speed playback, permitting noise-free still-frame and double-speed playback. For equipment built to the NTSC standard, to attain high-density recording, various techniques including a 90° phase-shift color signal processing technique, double l... View full abstract»

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  • Power spectra of channel codes for digital magnetic recording

    Publication Year: 1978, Page(s):321 - 323
    Cited by:  Papers (18)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (360 KB)

    The power spectral density (PSD) is the average power per unit frequency of encoded random data transmitted over a perfect channel. The one-sided PSDs of a number of channel codes of recent interest in digital magnetic recording are calculated from codeword dictionaries and state diagrams. Given here are: View full abstract»

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  • System response and extra bit errors

    Publication Year: 1978, Page(s):324 - 326
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (200 KB)

    A simplified model of a digital disc system and its response to an extra bit error is examined. Calculations of the resultant bitshift of a 2-F waveform peak as a function of extra bit pulse amplitude and timing are presented. The detection of extra bits on a system is discussed. View full abstract»

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  • Position sensing for high track density recording

    Publication Year: 1978, Page(s):327 - 329
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (352 KB)

    Progress towardhigher digital areal densities is related to the data track position sensing accuracy obtainable in future disk drives. In most systems available, position sensing is done remotely from the data track and subject to different dimensional stability conditions. To obtain higher track densities, position sensing reference information must be moved near the data track. Several technique... View full abstract»

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  • Reduction of the average access time with thin-film head arrays

    Publication Year: 1978, Page(s):330 - 332
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (264 KB)

    The average access time, ta, of a moving head disc file can be drastically reduced by the application of multi-track Thin-Film Head Arrays. It is shown analytically that ta= ts+ 16/15(Sm/a)1/2, where tsis the settling time, Sm, the maximum seek length and a, the constant acceleration and deceleration. When eight arrays ea... View full abstract»

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  • Study of the effect of static/dynamic Coulomb friction variation at the tape-head interface of a spacecraft tape recorder by non-linear time response simulation

    Publication Year: 1978, Page(s):333 - 335
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (376 KB)

    NASA's Voyager 1977 mission to Jupiter-Saturn utilizes a magnetic digital tape recorder (DTR) on each of the two flyby spacecrafts. It has been experimentally determined that about 97% of the total output torque of the drive motor of the Voyager DTR's is required to overcome the static/dynamic Coulomb friction at the tape-head interface while the remaining 3% of the torque is utilized to overcome ... View full abstract»

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  • Flexible disk--Read/write head interface

    Publication Year: 1978, Page(s):336 - 338
    Cited by:  Papers (12)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (408 KB)

    The response of a rotating flexible magnetic disk interacting with a stationary read/write head is analyzed using a theory that accounts for the effects of bending forces, membrane forces of rotation, and inertia forces. The solution thus obtained is coupled with the solution to the Reynolds equation to determine the pressure profile and film thickness (flying height) between the head and disk. View full abstract»

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  • A predictive analysis for optimum contour-after-wear for magnetic heads

    Publication Year: 1978, Page(s):339 - 341
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (384 KB)

    Reliable reproduction of recorded signals is dependent upon a good head-tape interface, and particularly, upon adequate contact pressure at the gap. In the case of grooved magnetic heads the pressure profiles are complex 3-dimensional surfaces. The head contours, as machined, may cause pressure profiles which are unfavorable to good signal reproduction. A mathematical analysis is outlined, which f... View full abstract»

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  • Magnetic strip cartridge for rotating-head file

    Publication Year: 1978, Page(s):342 - 344
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (624 KB)

    A strip of magnetic tape is attached to a stiff nonmagnetic backing sheet so that it can lie flat and be contained in an envelope. When partially withdrawn from the envelope, a loop is formed from the strip. The loop can be wrapped around a rotating head assembly for writing and reading and can be moved along the axis of the rotating head to register a multiplicity of tracks. Experimental results ... View full abstract»

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  • A new high permeability grain oriented Fe-3%Si steel

    Publication Year: 1978, Page(s):345 - 349
    Cited by:  Papers (3)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (392 KB)

    The metallurgy of a new high permeability magnetic steel with Goss texture is shortly described. Some details are given on the magnetic properties obtained and on the magnetic losses measured in transformers built with this steel. View full abstract»

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  • Approaches to the lowest core loss in grain-oriented 3% silicon steel with high permeability

    Publication Year: 1978, Page(s):350 - 352
    Cited by:  Papers (17)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (424 KB)

    In order to determine the most favorable approach to any reduction in core loss of high permeability silicon steel, detailed investigation on several factors affecting core loss has been made. The results indicated that only a small reduction was achieved by metallurgical approaches such as controls of texture and macrostructure. Any further reduction requires applications of domain-subdividing me... View full abstract»

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  • Some effects of stress in Goss-oriented silicon-iron

    Publication Year: 1978, Page(s):353 - 355
    Cited by:  Papers (15)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (312 KB)

    The magnetic characteristics of Goss-oriented 3% silicon-iron are dependent to a large extent on mechanical stress. This paper describes some effects of applying orthogonal planar stresses to single samples of commercial silicon-iron. Tensile or compressive stresses up to 10 MN/m2were applied simultaneously along and perpendicular to the rolling direction and the material was magnetized... View full abstract»

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  • Rotational power losses in 3% SiFe as a function of frequency

    Publication Year: 1978, Page(s):356 - 358
    Cited by:  Papers (26)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (304 KB)

    Rotational power losses per cycle Pr/f have been measured as a function of rotational frequency f, between about 0 and 25 Hz, on grain oriented and isotro pic 3% SiFe, under different magnetization conditions, up to almost complete saturation. Loss measurements were performed from the rate of change of the angular velocity of a top, spinning freely in a uniform magnetic field, on which ... View full abstract»

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  • Rotational hysteresis in polycrystalline alloys

    Publication Year: 1978, Page(s):359 - 361
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (360 KB)

    Rotational hysteresis has been studied at very low rotational speeds in nearly isotropic polycrystalline materials. Measurements were made on disc shaped samples of pure iron, 1.2% C steel and mild steel. The magnitude and direction of the moment were measured as the disc was rotated starting from an initial magnetization parallel to the external field. For large angles of rotation the measurement... View full abstract»

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  • Theory of negative magnetostriction in grain oriented 3% SiFe for various inductions and applied stresses

    Publication Year: 1978, Page(s):362 - 364
    Cited by:  Papers (14)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (376 KB)

    A theoretical model is presented to quantitatively account for the magnetostrictive behavior of grain oriented 3% SiFe laminations as a function of induction B and of applied tensile stress. Static magnetostriction measurements on high permeability longitudinal laminations show that the elongations Δ1/1 are negative for all B values, except close to saturation, reaching a deep minimum peak fo... View full abstract»

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  • On magnetic properties of Fe-Si-Mn alloy sheet

    Publication Year: 1978, Page(s):365 - 367
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (312 KB)

    Fe-Si-Mn alloys composed of 3.5-7,5%, 0-3.5%Mn and 90-96.5%Fe were melted in argon and hot-rolled. Measurements of their magnetic properties and electrical resistivity indicate that the addition of manganese to higher silicon-iron alloys improves in permeability and coercive force of the alloys. Maximum permeability as high as 83000 is obtained when the alloy of 6.70%Si, 0.55%Mn and 92.75%Fe is qu... View full abstract»

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  • The impedance of a finite length coil immersed in a circular cylindrical conducting structure

    Publication Year: 1978, Page(s):368 - 370
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (344 KB)

    The problem of calculating the impedance of a finite length solenoid immersed in a multiregion cylindrical structure is examined. The transmission line modelling technique is introduced to deal with a large number of regions in a simple and routine way. Bessel functions are completely avoided by replacing each region equivalent T.L. by a cascade connection of elementary T-circuits. The input imped... View full abstract»

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  • A numerical solution of transient nonlinear eddy-current problems including moving iron parts

    Publication Year: 1978, Page(s):371 - 373
    Cited by:  Papers (16)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (464 KB)

    The two-dimensional diffusion equation with nonperiodic driving term is solved by a finite-difference method. Moving parts, inductance-limited eddy currents, and strong saturation of the ferromagnetic materials are taken into account. The numerical procedure is based on time stepping and iterative solution by successive line overrelaxation. The method is used for the calculation of the dynamic beh... 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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Meet Our Editors

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