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Magnetics, IEEE Transactions on

Issue 6 • Date Nov. 1998

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Displaying Results 1 - 19 of 19
  • IEEE Transactions on Magnetics 1998 Subject Categories

    Publication Year: 1998 , Page(s): 3931 - 3932
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  • 1998 Index IEEE Transactions on Magnetics Vol. 34

    Publication Year: 1998 , Page(s): 1 - 33
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    Freely Available from IEEE
  • Subject index

    Publication Year: 1998 , Page(s): 33 - 103
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  • Three-dimensional analytic model of permanent magnet axial flux machine

    Publication Year: 1998 , Page(s): 3897 - 3901
    Cited by:  Papers (18)  |  Patents (1)
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    A three-dimensional (3-D) magnetic field problem in an axial flux machine with a toroidal winding is considered. The precise solutions generated by the integral transform and Fourier methods in elementary subregions are joined using the iterative Schwartz algorithm. The comparison between two dimensional and 3-D models is performed and a correction factor taking into account the radial variation of the magnetic flux is given View full abstract»

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  • Calculation of no-load induction motor core losses using the rate-dependent Preisach model

    Publication Year: 1998 , Page(s): 3876 - 3881
    Cited by:  Papers (11)
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    In this paper the authors present a two-step algorithm for predicting the core losses in an electrical machine. As a first step, the flux patterns in the cross section of the machine are calculated by using a time stepped two-dimensional finite element (FE) model, neglecting hysteresis and eddy currents in the laminated core. The second step consists in enforcing the calculated tooth and yoke flux waveforms to a one-dimensional FE lamination model in which the variation along the thickness of the induction and of the induced eddy currents is considered. The hysteretic behavior of the ferromagnetic material is taken into account by, means of a rate-dependent Preisach model. The outlined procedure is applied to a 3 kW squirrel-cage induction motor with either open or closed rotor slots, the former yielding elevated flux harmonics. Computation results and measurements at no-load (phase currents, stator tooth flux, and total iron losses) are compared View full abstract»

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  • Fast Preisach-based magnetization model and fast inverse hysteresis model

    Publication Year: 1998 , Page(s): 3857 - 3866
    Cited by:  Papers (24)
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    Fast computational methods for Preisach-based models and their inverses are presented. The methods are based on a differential equation approach to computing a sequence of magnetization values due to a sequence of applied fields. The method used to speed up calculations can be applied to any Preisach model. The Della Torre, Oti, Kadar model was used here as an illustration. Sequential computations for the magnetization model are substantially faster than for standard Preisach models with comparable output error. Computations for the inverse hysteresis model are even faster than for the model. Using the inverse, open loop control of magnetic hysteresis is simulated, showing hysteretic material tracking a desired magnetization in a linear manner for both major loops and minor loops, with less than 2% error in inversion for the waveforms used. The effect of misidentification of material parameters on operation of the inverse is also investigated through simulations View full abstract»

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  • Determination of the capture radii of magnetite bearing hydroxide flocs in magnetic filtration

    Publication Year: 1998 , Page(s): 3902 - 3909
    Cited by:  Papers (7)
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    Magnetic filtration may be applied in water technology for the separation of flocs which are formed in a flocculation tank together with magnetite as an additive. The capture radius is an important mathematical quantity to calculate the performance of such filters in advance. Thus, the capture radii of magnetite bearing copper hydroxide flocs were measured with a direct visual evaluation of the floc trajectories in the neighborhood of a single magnetized wire. For this purpose, an experimental setup was assembled, which allowed the observation and the measurement of the trajectories. With the image processing system used, it was possible to observe flocs larger than 30 μm and the flow velocity was limited to a maximum value of 20 mm/s. Capture radii were calculated by the established single-wire theory under the assumption of potential and creeping flow conditions. It has been proved that further information on the solids content of the flocs, which strongly influences the floc susceptibility, was necessary to obtain an agreement between the experimental data and the theoretical predictions. By introducing a flee size dependent solids content into the single-wire theory, measured by means of sedimentation analysis, an accurate description of the observed capture radii was possible View full abstract»

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  • Adaptive finite element mesh refinement techniques in three-dimensional micromagnetic modeling

    Publication Year: 1998 , Page(s): 3922 - 3930
    Cited by:  Papers (23)
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    Two different methods to adaptively refine tetrahedral finite element meshes are presented. The influence of the mesh refinement on the obtained results of micromagnetic calculations is demonstrated for the case of magnetization patterns in soft magnetic platelets. The specific addition of vertices and finite elements in inhomogeneous regions is used to resolve the magnetic structure on small length scales. A method discussed in detail is the shrinking of finite elements in regions with strong inhomogeneities View full abstract»

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  • Characterization of electrodeposited magnetic multilayers

    Publication Year: 1998 , Page(s): 3910 - 3912
    Cited by:  Papers (3)
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    Electrodeposition will prove to be a promising candidate for the preparation of magnetic nanostructures. Multilayered Co/Pt nanostructures grown on a Cu(111) single-crystal substrate by electrodeposition under potential control exhibit a remanent perpendicular magnetization and a large coercivity, which depend on the deposition overpotential and hence the multilayer growth mechanism. Giant magnetoresistance and oscillatory antiferromagnetic interlayer coupling have been observed in a face-centered cubic (fcc) (111) textured Co/Cu multilayered nanostructure. Moreover, a large saturation magnetoresistance of more than 20% has been achieved at room temperature for a heterogeneous Co-Cu alloy, which consists of ultrafine fcc Co-rich clusters in a nonmagnetic Cu matrix View full abstract»

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  • Temperature- and time-dependent Preisach model for a Stoner-Wohlfarth particle system

    Publication Year: 1998 , Page(s): 3867 - 3875
    Cited by:  Papers (15)
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    In this paper, a dynamic (time and temperature dependent) Preisach model is described. In the Preisach plane one uses a double well potential distribution calculated with the Stoner-Wohlfarth model. Both static and dynamic interactions for a ultrafine particulate system are taken into account in order to simulate various magnetization processes, such as: field-cooled (FC), zero field-cooled (ZFC), thermo-remanent magnetization (TRM), magnetic relaxation in applied field (MR), and the major hysteresis loop (MHL) as a function of temperature. The results of the simulations are in good qualitative agreement with experimental data obtained for ferromagnetic ultrafine particulate systems View full abstract»

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  • Frequency modulation in video tape recorders

    Publication Year: 1998 , Page(s): 3916 - 3921
    Cited by:  Papers (3)  |  Patents (3)
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    Essentially all consumer video tape recorders use frequency modulation for the luminance component of the video signal and demodulation is performed by zero-crossing detection. Distortion-free video requires that the zero crossings of the frequency modulation waveforms be preserved exactly. In this paper, the complete set of mathematical conditions for zero-crossing preservation is derived from first principles. While some of these conditions have been discussed previously, the complete set derived here is believed to be novel View full abstract»

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  • Reducing hysteresis in magnetostrictive-piezoelectric magnetic sensors

    Publication Year: 1998 , Page(s): 3913 - 3915
    Cited by:  Papers (6)
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    In this paper, we present a method to avoid hysteresis in magnetostrictive-piezoelectric sensors. It is based on the application of an alternating magnetic field of a frequency different than the piezoelectric exciting frequency that supplies enough energy to overcome any domain wall pinning. The signal is filtered with a notch filter synchronized to the magnetic field frequency and thus it does not contribute to the useful response of the sensor. The results show an appreciable decrease in the magnetic hysteresis and also a small decrease in the sensitivity of the sensor View full abstract»

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  • Hysteresis motor using magnetically anisotropic Fe-Cr-Co magnet

    Publication Year: 1998 , Page(s): 3888 - 3896
    Cited by:  Papers (4)  |  Patents (1)
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    For the rotor ring of the hysteresis motor, semihard Alnico magnets have been almost applied until now. However, the hysteresis motor using Alnico magnets has several disadvantages. In order to improve the disadvantages of conventional hysteresis motors, the Fe-Cr-Co magnet steel with magnetic anisotropy is applied for hysteresis rotor ring. Magnetic anisotropy is used to cause large reluctance torque and large hysteresis torque at synchronous pull out. It is made clear from experimental results that these hysteresis motors have large output, high efficiency, and high power factor, to add the reluctance torque to hysteresis torque effectively View full abstract»

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  • Dynamical micromagnetics by the finite element method

    Publication Year: 1998 , Page(s): 3842 - 3852
    Cited by:  Papers (23)
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    We developed a new numerical procedure to study dynamical behavior in micromagnetic systems. This procedure solves the damped Gilbert equation for a continuous magnetic medium, including all interactions in standard micromagnetic theory in three-dimensional regions of arbitrary geometry and physical properties. The magnetization is linearly interpolated in each tetrahedral element in a finite element mesh from its value on the nodes, and the Galerkin method is used to discretize the dynamic equation. We compute the demagnetizing field by solution of Poisson's equation and treat the external region by means of an asymptotic boundary condition. The procedure is implemented in the general purpose dynamical micromagnetic code (GDM). GDM uses a backward differential formula to solve the stiff ordinary differential equations system and the generalized minimum residual method with an incomplete Cholesky conjugate gradient preconditioner to solve the linear equations. GDM is fully parallelized using MPI and runs on massively parallel processor supercomputers, clusters of workstations, and single processor computers. We have successfully applied GDM to studies of the switching processes in isolated prolate ellipsoidal particles and in a system of multiple particles View full abstract»

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  • An evolutionary algorithm for the optimal design of induction motors

    Publication Year: 1998 , Page(s): 3882 - 3887
    Cited by:  Papers (26)
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    This paper describes the application of an evolutionary algorithm to the design of induction motors. It is shown that the use of an evolutionary algorithm offers advantages over other approaches. These include a high rate of global convergence and the ability to handle discrete variables View full abstract»

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  • Analytical determination of eddy currents in a hollow sphere excited by an arbitrary dipole

    Publication Year: 1998 , Page(s): 3822 - 3829
    Cited by:  Papers (7)
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    In this paper an analytical solution for the quasistationary eddy current distribution in a hollow sphere is presented using a divergence free vector potential derived from another spatial vector function by applying the curl operator. The field is excited by a dipole of arbitrary orientation and position. The dissipated power is also considered and hints are given for the analytical treatment of multishield problems excited by current loops View full abstract»

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  • Spin-wave emitting diodes and spin diffusion in magnetic multilayers

    Publication Year: 1998 , Page(s): 3837 - 3841
    Cited by:  Papers (18)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (164 KB)  

    When a dc current traverses a magnetic multilayer, a spontaneous precession of the magnetization is predicted to arise. In the present work, we discuss three different configurations for this device. We show that the multilayer must not exhibit complete mirror symmetry with respect to the median plane of the precessing layer. Also, we solve the Valet-Fert spin-diffusion equations in the various layers. The results lead to certain optimum values for the layer thicknesses and for the conduction-electron spin-relaxation time in some layers. Finally, we propose an alternate mechanism to “pump” the conduction-electron spins View full abstract»

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  • Intrinsic low-field loss in microwave ferrites

    Publication Year: 1998 , Page(s): 3830 - 3836
    Cited by:  Papers (5)
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    The off-resonance damping parameter due to the three-magnon splitting process is calculated by extending the theory of intrinsic magnetic relaxation processes. The imaginary part of the diagonal component of the microwave permeability tensor is found to decrease with increasing internal magnetic field and to be proportional to the absolute temperature. In magnitude it is somewhat smaller than the subthreshold absorption under parallel pumping, which has a similar physical origin and has previously been calculated and verified by experiments. Since the calculated magnetic damping occurs in all magnetic materials, it is expected to contribute significantly to the insertion loss of many ferrite microwave devices View full abstract»

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  • Artificial neural networks for finite element modeling of giant magnetostrictive devices

    Publication Year: 1998 , Page(s): 3853 - 3856
    Cited by:  Papers (1)
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    The author investigates the contribution of artificial neural networks to the improvement of giant magnetostrictive devices nonlinear modeling. In fact, the use of experimental data through artificial neural networks modeling allows the introduction of the magnetostrictive coupling. The proposed model has been tested on a basic magnetostrictive actuator 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