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Magnetics, IEEE Transactions on

Issue 7 • Date July 2012

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Displaying Results 1 - 23 of 23
  • [Front cover]

    Publication Year: 2012 , Page(s): C1
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  • IEEE Transactions on Magnetics publication information

    Publication Year: 2012 , Page(s): C2
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  • Table of contents

    Publication Year: 2012 , Page(s): 2101 - 2102
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  • Micromagnetic Investigation of the S-State Reconfigurable Logic Element

    Publication Year: 2012 , Page(s): 2103 - 2111
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1383 KB) |  | HTML iconHTML  

    Magnetic nanostructures are promising for nonvolatile data storage applications, as well as for reconfigurable logic devices. The derived magnetic logic concepts are commonly relying on the magnetostatic coupling of small ensembles or larger chains and networks of nanostructures. Recently, we presented a simple single-layer logic element based on an S-shaped geometry. This reconfigurable device can be integrated with magnetoresistive elements and is relatively simple to fabricate. We present a detailed micromagnetic analysis of the geometrical parameter space in which the logic element performs reliably. The influence of imperfections on the device characteristics, that is, sidewall roughness and roundedness of the edges, is investigated. Special attention is paid to obtain configurations with symmetric input field values. View full abstract»

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  • Magnetic Fields and Forces in Permanent Magnet Levitated Bearings

    Publication Year: 2012 , Page(s): 2112 - 2120
    Cited by:  Papers (4)
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    Magnetic fields and magnetic forces from magnetic bearings made of circular Halbach permanent-magnet arrays are computed and analyzed. The magnetic fields are calculated using superposition of fields due to patches of magnetization charge at surfaces where the magnetization is discontinuous. The magnetic force from the magnetic bearing is computed using superposition of forces on each patch of magnetization charge. The magnetic force from a Halbach array magnetic bearing is compared to an annular ring bearing of the same dimensions. A comparison is also made between the results obtained using the magnetic surface charge method and the simpler approximate method using a 2-D analytic representation of the Halbach array fields. View full abstract»

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  • Analytical Prediction of Magnetic Field in Parallel Double Excitation and Spoke-Type Permanent-Magnet Machines Accounting for Tooth-Tips and Shape of Polar Pieces

    Publication Year: 2012 , Page(s): 2121 - 2137
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5096 KB) |  | HTML iconHTML  

    This paper presents an analytical method based on subdomain method for the computation of open circuit, armature reaction, and on-load magnetic field distribution in integer slot winding parallel double excitation and spoke-type tangential permanent-magnet machines. The proposed model takes into account for stator and rotor slots tooth tips and shape of polar piece. A 2-D exact analytical solution of magnetic field distribution is established. It involves solution of Laplace's and Poisson's equations in semi-closed stator and rotor slots, air-gap, buried permanent magnets into rotor semi-closed slots, and nonmagnetic region under magnets. Obtained exact analytical results of open circuit, armature reaction, and on-load magnetic field distribution are verified with those issued from the finite element method. View full abstract»

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  • Analytical Model of Eddy Current Loss in Windings of Permanent-Magnet Machines Accounting for Load

    Publication Year: 2012 , Page(s): 2138 - 2151
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4654 KB) |  | HTML iconHTML  

    This paper presents an analytical model for predicting open-circuit, armature reaction and on-load resistance limited eddy current losses in the conductors of surface-mounted permanent-magnet machines, based on the subdomain field model accounting for tooth-tips. The analytical model can be applied to machines having single-layer, two-radial-layer, or two-circumferential-layer windings. The interaction between spatial harmonics is accurately accounted for in the calculation of the AC copper loss. The investigation shows that neglecting the interaction in the analytical model has negligible influence on the prediction of total AC copper loss but results in significant error in the predicted loss distribution among conductors. The influence of tooth-tip dimension, conductor segmentation, and current on the AC copper loss is also investigated by the analytical model. The finite element analysis has verified the validity of the developed analytical model. View full abstract»

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  • Scalability Prospect of Three-Terminal Magnetic Domain-Wall Motion Device

    Publication Year: 2012 , Page(s): 2152 - 2157
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (832 KB) |  | HTML iconHTML  

    We studied a scaling property of a three-terminal domain wall (DW)-motion device, which is one of the promising candidates for future low-power nonvolatile memory and logic-in-memory architecture. Using several assumptions, we derived the scaling factor of the switching current, switching time, resistance of the write-current path, and data storage stability. We also quantitatively evaluated the variation of these parameters with the device size. It was found that the switching current and time decrease almost linearly with the device size, while the variation of the resistance of the write-current path is negligible. The switching current and time for 32-nm-wide device are less than 100 μA and 2 ns, respectively. A required critical field which assures a sufficient thermal stability of stored data was calculated for each generation. Furthermore, future issues and intrinsic limiter for the size reduction were discussed. View full abstract»

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  • Characterization of the Reader Width Using the Micro-Track Test in Perpendicular Recording

    Publication Year: 2012 , Page(s): 2158 - 2160
    Cited by:  Papers (2)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1305 KB) |  | HTML iconHTML  

    Micro-track test is a valuable tool used to characterize the electrical reader width in perpendicular recording. The test is based on trimming both sides of a track written with a single tone and followed by a cross-track scan of the remaining track. The reader cross-track profile or read sensitivity function is characterized by a narrow band measurement of the read-back signal as a function of cross-track position. With increasing track density, the signal amplitude decreases due to incomplete media saturation and to an increase in the off-track noise due to percolation and opposite polarity media saturation. These effects cause a lump at the edge of the micro-track profile that changes the width of the profile (MT10 and MT50). Micro-magnetic analysis indicates that the off-track demagnetization field creates a track-edge section in the media with opposite polarity relative to the originally written track. This section is coherent with the main track and decreases the read-back signal during the scan of the micro-track. Consequently, the shape of the cross-track read sensitivity function becomes distorted, causing a reduction in MT10 and a side lump. The solution to this problem is to increase the amplitude of the micro-track read-back signal by reduced trimming and by the use of a higher density (KFCI) in the main track that minimizes the off-track demagnetization field. These test improvements are shown to preserve the integrity of the micro-track profile and to enable an accurate measurement of MT10 and MT50. Optimizing reader and writer widths in perpendicular recording requires an accurate measurement of these parameters. View full abstract»

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  • An Extended Iterative Finite Element Model for Simulating Eddy Current Testing of Aircraft Skin Structure

    Publication Year: 2012 , Page(s): 2161 - 2165
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (693 KB) |  | HTML iconHTML  

    This paper presents a new finite element (FE) model for three-dimensional simulation of eddy current testing of aircraft skin structure. More specifically, scanning of ferrite-core probe over aluminum plates riveted by steel fasteners is simulated. The model uses different FE meshes to discretize the ferrite core, the aluminum plates, and the fasteners. The coil is not meshed. The reduced magnetic vector potential generated by the induced currents and/or magnetization in each domain is calculated and updated by an iterative procedure. Re-meshing due to changing probe position in conventional models is avoided. Efficiency of the model is demonstrated. View full abstract»

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  • Investigation of Model Simplification and Its Influence on the Accuracy in FEM Magnetic Calculations of Gearless Drives

    Publication Year: 2012 , Page(s): 2166 - 2177
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2596 KB) |  | HTML iconHTML  

    Finite-element models of electrical motors often become very complex and time consuming to evaluate when taking into account every little detail. There is therefore a need for simplifications to make the models computational within a reasonable time frame. This is especially important in an optimization process, as many iterations usually have to be performed. The focus of this work is an investigation of the electromagnetic part of a gearless mill drive based on real system data which is part of a larger project building a multiphysics model including electromagnet, thermal, and structural interactions. This multiphysics model will later on be used for simulating and parameter optimization of a gearless mill drive with the use of Evolution Strategies which necessitates the reduction in computation time. What has been investigated is how model simplifications influence the accuracy on the calculated forces and torque coming from the drive where each simplification made is described and justified. To further reduce the evaluation time, it is examined how coarse the mesh can be, while still predicting the results with a high accuracy. From this investigation, it is shown that there are certain ratios between the mesh size in the air gap and the iron core, which will result in an optimal determination of the forces and torque. It will be shown that it is possible, just through simplifications and choosing the correct mesh size, to reduce the computational time by 98%, keeping an accuracy for the torque and forces of less than 0.3% and 1.2%, respectively. View full abstract»

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  • Analytical Armature Reaction Field Distribution of Slotless Brushless Machines With Inset Permanent Magnets

    Publication Year: 2012 , Page(s): 2178 - 2191
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4874 KB) |  | HTML iconHTML  

    An analytical armature reaction magnetic field calculation is proposed for slotless brushless machines with inset permanent magnets (PMs). The rotor/stator back-irons are assumed to have infinite permeability and therefore the analytical solutions are obtained for the winding, air-gap, and magnets regions. The analytical expressions can be used for the brushless slotless surface-inset PM machines with any armature current waveform and any number of phases. The effects of the iron inter-poles on the armature reaction field have been studied. To verify the model, the analytical results have been compared with those obtained from finite-element analyses (FEA). View full abstract»

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  • Novel Method for Selective Nonlinear Flux Guide Switching for Contactless Inductive Power Transfer

    Publication Year: 2012 , Page(s): 2192 - 2195
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (935 KB) |  | HTML iconHTML  

    Efficient inductive power transfer has become an area of increasing scientific interest as it can solve some problems associated with traditional wired or contact power transmission. These include but are not limited to corrosion, mechanical friction, clutter and impracticality in places like underwater and subterranean applications. This wireless energy transfer is made possible by the optimization of electromagnetic induction, circuit frequency resonance all achieved with advanced power electronics. One of the components of this technology is the precise delivery of the incident electromagnetic fields to the precise location to which they are converted to power via induction, without indiscriminate emission of these electromagnetic fields inefficiently into the surrounding areas. This paper presents a method in achieving bounded spatial freedom using flux-guide saturation for flux delivery to one or more secondary coils for contactless inductive power transfer. The experiments demonstrate the principle of using the nonlinearity of a ferrite flux shield in order to “open up” a flux path from the primary to the secondary coil to achieve inductive power transfer. View full abstract»

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  • Air-Gap Flux Density Characteristics of Salient Pole Synchronous Permanent-Magnet Machines

    Publication Year: 2012 , Page(s): 2196 - 2204
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1595 KB) |  | HTML iconHTML  

    The detailed knowledge of the field distribution in the air gap is of main importance for predicting and optimizing the performance of electric machines. In this paper, the air-gap flux density of a salient pole permanent-magnet (PM) synchronous machines is determined and investigated using a new analytical model. The stator slotting and rotor saliency effect, and also the air-gap MMF harmonics are considered. Different no-load and under load simulations are performed to show the permeance effect (rotor saliency and stator slotting) on the air-gap flux density characteristics of this type of machine. The simulations results show that as results of the permeance harmonics additional harmonics are induced on the air-gap flux density and these harmonics are very sensitive on the rotor pole shape parameters. Furthermore, the time domain analysis shows also that the permeance harmonics leads to the fluctuation of the resulting air-gap flux density harmonics with the time. View full abstract»

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  • Controlling Rotor Vibrations of a Two-Pole Induction Machine With Unipolar Actuator

    Publication Year: 2012 , Page(s): 2205 - 2210
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (926 KB) |  | HTML iconHTML  

    A three-phase two-pole induction machine has been fitted with coils wound around the machine shaft inside the end shields of the machine. The coils induce unipolar flux in to the machine when supplied with a controllable voltage supply. These windings act as a unipolar actuator that can be used to produce radial force on the rotor. The machine does have a short-circuited extra four-pole stator-winding to reduce unbalanced magnetic pull (UMP) due to the interaction of the two- and four-pole flux components. In two-pole machines, unipolar flux and slot harmonics cause the whirling orbit of an eccentric rotor to pulsate with double slip frequency. The unipolar actuator will mitigate this pulsation when voltage is supplied to the unipolar coils at slip frequency and at correct phase. Current needed to remove pulsation is higher than what is needed to counter the measured unipolar flux. Effects of zero frequency unipolar flux are studied. Theory and measurements are presented. View full abstract»

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  • A Novel Positioning and Orientation System Based on Three-Axis Magnetic Coils

    Publication Year: 2012 , Page(s): 2211 - 2219
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2212 KB) |  | HTML iconHTML  

    The positioning and orientation system consists of three-axis generating coils and three-axis sensor coils in quasi-static magnetic field. The three-axis generating coils are fixed orthogonally and excited by the alternating current (AC) signals with different frequencies. They create the magnetic field that is equivalent to that generated by three orthogonal magnetic dipoles. Using the amplitude and phase information of the sensing signals in the sensor coils, the position and orientation parameters of the sensor coils can be computed by using an appropriate algorithm. In this paper, a novel algorithm is proposed to determine the position of the sensor coil object by some equations directly, so that its position and orientation parameters can be calculated much easier and faster. Based on this method, a system with support circuitry is designed with some special signal acquisition and sampling methods. Especially, a signal extraction (function fitting) method is proposed to pick up the coupling AC signal magnitude of the sensor coils, which simplifies the hardware circuitry and improves the signal acquisition accuracy. The simulation and real experimental results show that the system works satisfactorily with good accuracy. View full abstract»

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  • Incidence Angle Effect of Energetic Carbon Ions on Deposition Rate, Topography, and Structure of Ultrathin Amorphous Carbon Films Deposited by Filtered Cathodic Vacuum Arc

    Publication Year: 2012 , Page(s): 2220 - 2227
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    The effect of the incidence angle of energetic carbon ions on the thickness, topography, and structure of ultrathin amorphous carbon (a-C) films synthesized by filtered cathodic vacuum arc (FCVA) was examined in the context of numerical and experimental results. The thickness of a-C films deposited at different incidence angles was investigated in the light of Monte Carlo simulations, and the calculated depth profiles were compared with those obtained from high-resolution transmission electron microscopy (TEM). The topography and structure of the a-C films were studied by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS), respectively. The film thickness decreased with the increase of the incidence angle, while the surface roughness increased and the content of tetrahedral carbon hybridization (sp3) decreased significantly with the increase of the incidence angle above 45°, measured from the surface normal. TEM, AFM, and XPS results indicate that the smoothest and thinnest a-C films with the highest content of sp3 carbon bonding were produced for an incidence angle of 45°. The findings of this study have direct implications in ultrahigh-density magnetic recording, where ultrathin and smooth a-C films with high sp3 contents are of critical importance. View full abstract»

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  • Modeling of Axial Magnetic Force and Stiffness of Ring-Shaped Permanent-Magnet Passive Vibration Isolator and Its Vibration Isolating Experiment

    Publication Year: 2012 , Page(s): 2228 - 2238
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4482 KB) |  | HTML iconHTML  

    Magnetic suspension vibration isolators have attracted more and more attention in the field of semiconductor industry and high precision equipments. A novel ring-shaped permanent-magnet passive vibration isolator is mainly reported in this paper. An analytical expression of axial magnetic force of the isolator is derived and validated by the finite element analysis and experiment. It proves that the analytical expression is efficient. An analytical expression of the axial stiffness of the isolator is deduced by derivative of the axial magnetic force with respect to the axial relative displacement of the inner ring. Furthermore, the parametric study of the axial magnetic force and stiffness are carried out. As a ring-shaped permanent-magnet passive vibration isolator case study, the isolator was constructed by four couples of the ring-shaped permanent magnets. The vibration isolation performance of the isolator was subsequently calculated and tested. The experimental results have shown a good agreement with the calculated ones. It demonstrates that the proposed isolator can realize low-frequency vibration isolation. View full abstract»

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  • Performance Evaluation of Maximum-Likelihood Page Detection for 2-D Interference Channel

    Publication Year: 2012 , Page(s): 2239 - 2242
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1042 KB) |  | HTML iconHTML  

    The issue of maximum-likelihood page detection (MLPD) of a two-dimensional (2-D) interference channel corrupted by additive white Gaussian noise is studied. A new way of analyzing the performance of MLPD is proposed which provides a distinct understanding of the MLPD for 2-D interference channels. An approximated bounding method is also proposed which can accurately predict the performance bound while greatly reducing the computational complexity. View full abstract»

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  • IEEE Magnetics Letters

    Publication Year: 2012 , Page(s): 2243
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    Freely Available from IEEE
  • IEEE Xplore Digital Library [advertisement]

    Publication Year: 2012 , Page(s): 2244
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    Freely Available from IEEE
  • IEEE Magnetics Society Information

    Publication Year: 2012 , Page(s): C3
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    Freely Available from IEEE
  • IEEE Transactions on Magnetics institutional listings

    Publication Year: 2012 , Page(s): C4
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    Freely Available from IEEE

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