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Magnetics, IEEE Transactions on

Issue 1  Part 1 • Date Jan. 2008

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Displaying Results 1 - 18 of 18
  • [Front cover]

    Publication Year: 2008 , Page(s): C1
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  • IEEE Transactions on Magnetics publication information

    Publication Year: 2008 , Page(s): C2
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  • Table of contents

    Publication Year: 2008 , Page(s): 1
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  • IEEE Magnetics Society Distinguished Lecturers for 2008

    Publication Year: 2008 , Page(s): 2 - 5
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  • Micro-Brillouin Light Scattering Spectroscopy of Magnetic Nanostructures

    Publication Year: 2008 , Page(s): 6 - 12
    Cited by:  Papers (40)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (627 KB) |  | HTML iconHTML  

    We describe a new technique, micro-Brillouin light scattering spectroscopy, for investigation of spin wave dynamics in magnetic nanostructures. The technique offers advantages for studies of small magnetic squares with closure domain structure and magnetic nanoelements similar to those used in magnetic random access memory. The technique is particularly effective in two-dimensional mapping of spin waves excited by a single nanocontact due to the spin torque transfer effect. View full abstract»

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  • Influence of {\hbox {Fe}}_{2}{\hbox {O}}_{3} Stoichiometry on Initial Permeability and Temperature Dependence of Core Loss in MnZn Ferrites

    Publication Year: 2008 , Page(s): 13 - 16
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (378 KB) |  | HTML iconHTML  

    We investigated the relationship between magnetic properties of MnZn ferrites and Fe2O3 stoichiometry by measuring magnetic properties, electrical resistivity, and density. We used a scanning electron microscope to observe the fractured surface of sintered samples. MnZn ferrites were prepared by adapting the conventional ceramic technique. Toroidal cores were sintered at 1355degC for 4 h with 4% oxygen. The results show that the initial permeability and power losses of MnZn ferrites strongly depend on the content of Fe2O3. And there is an obvious secondary maximum peak in the curve of mui versus T at about 100degC. The initial permeability mui reaches a maximum value and the power loss is lowest over a wide temperature ranging from 20degC to 180degC when the content of Fe2O3 is 52.5 mol%. View full abstract»

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  • Optimal Design of Magnetostrictive Composites: An Analytical Approach

    Publication Year: 2008 , Page(s): 17 - 23
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB) |  | HTML iconHTML  

    Giant magnetostriction materials, such as Terfenol-D, have allowed the development of a new class of actuators and sensors based on magnetoelastic properties. However, their mechanical properties are a limiting factor for some applications. Composites, made of Terfenol-D particles in a matrix, can bypass these limitations, improving the overall mechanical properties while maintaining the magnetostriction effect. But, to optimize the design of magnetostrictive composites, advanced modeling tools are needed. This paper proposes a homogenization model based on inclusion problems. It compares modeling results to experimental data from the literature, and it illustrates the use of the model as a tool for optimal design. View full abstract»

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  • Generalized Permeability Tensor Model: Application to Barium Hexaferrite in a Remanent State for Self-Biased Circulators

    Publication Year: 2008 , Page(s): 24 - 31
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (381 KB) |  | HTML iconHTML  

    We describe a theoretical approach for determining the permeability tensor of polycrystalline ferrites regardless of their magnetization state. To take into account both the demagnetizing dynamic fields related to the magnetic domain and grain shapes and the magnetic interactions between adjoining domains and between adjoining grains, we transform the classical Landau-Lifschitz-Gilbert equation into a coupled two-equation system. We introduce statistical distribution laws for both the domain and grain demagnetizing coefficients into the calculation to take the domain and grain shape diversity into account and derive static vectorial quantities such as the internal magnetic dc field and magnetization in each domain that depends on the applied dc magnetic field from the Stoner-Wohlfarth hysteresis model. We compare results with those for existing models for various magnetized states. Then we apply the model to predict the permeability tensor behavior of barium hexaferrite thin film, especially in the remanent state, which is of great interest for the design of self-biased Y-junction circulators in the millimeter-wave range. View full abstract»

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  • Magnetic Flux Density and Vector Potential of Uniform Polyhedral Sources

    Publication Year: 2008 , Page(s): 32 - 36
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (133 KB) |  | HTML iconHTML  

    The magnetic flux density and the magnetic vector potential produced by a uniform current density or a uniform magnetization inside an arbitrary polyhedron are calculated analytically. The obtained closed-form expressions are remarkably simple and provided in an intrinsic vector form, independently of any reference frame. They are well suited to cope with the data structures, i.e., faces-edges and edges-vertices incidence matrices, provided by unstructured polygonal meshes generators. The expressions obtained contain only elementary functions, and computed results illustrate their effectiveness. View full abstract»

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  • A New Identification and Implementation Procedure for the Isotropic Vector Preisach Model

    Publication Year: 2008 , Page(s): 37 - 42
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (223 KB) |  | HTML iconHTML  

    A factorable Preisach distribution function is a reasonable assumption in modeling soft magnetic materials. With this assumption it is possible to define and employ a single-input Preisach function for easier implementation and identification of a scalar Preisach model. On the basis of this simplification, we developed a new method for identification and implementation of the isotropic vector Preisach model. With the aid of a newly derived equation, the Preisach function of the vector Preisach model can be identified from the corresponding scalar one. We verified the correctness of the proposed method by comparing the results of scalar and vector models in a scalar condition of input variation. View full abstract»

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  • Magnetic Flux Density Tracking Control for the Measurement of Isomagnetic Lines

    Publication Year: 2008 , Page(s): 43 - 51
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1788 KB) |  | HTML iconHTML  

    A fast measurement system that can characterize a magnet during manufacturing would be a great aid to quality control. The traditional approach measures the magnetic flux density across a specified plane to precisely characterize the magnet. However, this is a time-consuming process. To speed up the magnet characterization, we have developed a new characterization concept based on isomagnetic line inspection at a designated flux density, as well as a servo control system for isomagnetic line measurement and two measuring techniques (magnetic vector tracking and triple-point searching). Experimental results verify the feasibility and performance of the proposed method.Due to the increasing use of magnets in industrial applications, a measurement system that can characterize a magnet during manufacturing has become an important issue. This will be a great aid to quality control. The traditional approach measures the magnetic flux density across a specified plane to precisely characterize the magnet. However, this is a very time consuming process. To speed up the magnet characterization, this paper proposes a new characterization concept using an isomagnetic line inspection method at a designated flux density. In addition, a servo control system for isomagnetic line measurement and two measuring techniques (magnetic vector tracking and triple-point searching) are developed. Experimental results verify the feasibility and performance of the proposed methods. View full abstract»

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  • Analytical Solution for Cogging Torque in Surface Permanent-Magnet Motors Using Conformal Mapping

    Publication Year: 2008 , Page(s): 52 - 65
    Cited by:  Papers (65)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (807 KB) |  | HTML iconHTML  

    We present an analytical method for the calculation of cogging torque in surface permanent-magnet (PM) motors. The cogging torque is calculated by integrating the Maxwell stress tensor inside the air gap. The principle of complex relative air-gap permeance derived from conformal transformation of the slot geometry is used to take into account the effect of slotting and to calculate the radial and tangential components of the air-gap flux density required for integration of the tangential component of the Maxwell stress tensor. We implemented the proposed analytical solution on a 7-kW four-pole surface PM motor and compared the results with finite-element solutions. We present an example of finding the optimal magnet angular span to yield minimum cogging torque as an example of the effectiveness of the method. View full abstract»

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  • Finite-Element Transient Analysis of Induction Motors Under Mixed Eccentricity Fault

    Publication Year: 2008 , Page(s): 66 - 74
    Cited by:  Papers (43)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (572 KB) |  | HTML iconHTML  

    In a three-phase squirrel-cage induction motor, eccentricity is a common fault that can make it necessary to remove the motor from the production line. However, because the motor may be inaccessible, diagnosing the fault is not easy. We have developed a time-stepping finite-element method (FEM) that identifies mixed eccentricity (a combination of static and dynamic) by analysis, without direct access to the motor. The method overcomes the difficulty of applying FEMs to transient behavior. It simulates the spectrum of the line current of a production-line motor and compares it to the spectrum of a known healthy motor to detect eccentricity. Agreement between the simulation and actual measurements of eccentricity is good.Protection and fault diagnosis are integral to sound application of three-phase squirrel-cage induction motors in industry. Eccentricity is a common fault in induction motors that might force the motor to be removed from the production line. However, diagnosis of this fault due to inaccessibility to the rotor is not easy. Performance analysis, investigation and diagnosis of static, dynamic and mixed eccentricities at steady-state and during transient modes have already been published using analytical methods. However, study of static and dynamic eccentricities only at steady-state using finite element method (FEM) has been previously reported. This paper uses time stepping FE (TSFE) method with voltage-fed source for performance analysis and diagnosis of mixed eccentricity in induction motor at start up. The method used here overcomes the difficulty of FE application which makes it possible to analyze the transient behavior of a faulty induction motor. Spectra of line current of healthy motor and motor under mixed eccentricity conditions are predicted by simulation and then compared with the experimental results. This comparison shows a very good agreement between the simulation and test results. View full abstract»

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  • Design, Prototyping, and Analysis of a Low Cost Axial-Flux Coreless Permanent-Magnet Generator

    Publication Year: 2008 , Page(s): 75 - 80
    Cited by:  Papers (31)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (788 KB) |  | HTML iconHTML  

    This paper presents the design, prototyping, and analysis of a relatively small and cheap axial-flux three-phase coreless permanent-magnet generator. The excitation of the machine is done by rectangular flat shaped neodymium-iron-boron magnets. A two-dimensional model of the machine is analyzed with finite-element software to obtain the machine parameters. One special feature of the constructed generator is in the design and prototyping of nonferromagnetic holders to counteract centrifugal forces acting on magnets, especially at high speeds. By implementing the nonferromagnetic holders, one can expect to construct high-speed axial-flux permanent-magnet generators at low cost. View full abstract»

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  • Augmentation of Short-Span Seeking Performance Using Dynamic Saturation

    Publication Year: 2008 , Page(s): 81 - 83
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (207 KB)  

    We present a method for improving the short-span seeking performance of a recently proposed compensator-based control system for a dual-stage servo actuator. The method consists of replacing a constant saturation nonlinearity in the secondary loop of the dual-stage control system by a dynamic saturation nonlinearity. This results in a significantly faster response of the secondary actuator and hence faster seeking times. The improvement in seeking times is greatest for short-range seeks that are within the range of the secondary actuator. We also present experimental results comparing the performance of a dual-stage servo actuator with constant and with dynamic saturation in the secondary loop. View full abstract»

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  • Order form for reprints

    Publication Year: 2008 , Page(s): 84
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  • IEEE Magnetics Society Information

    Publication Year: 2008 , Page(s): C3
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  • IEEE Transactions on Magnetics institutional listings

    Publication Year: 2008 , Page(s): C4
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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