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Magnetics, IEEE Transactions on

Issue 9 • Date Sept. 2006

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Displaying Results 1 - 19 of 19
  • [Front cover]

    Publication Year: 2006 , Page(s): c1
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  • IEEE Transactions on Magnetics publication information

    Publication Year: 2006 , Page(s): c2
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  • Table of contents

    Publication Year: 2006 , Page(s): 2113 - 2114
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  • Nano /spl alpha/-Fe/epoxy resin composite absorber coatings fabricated by thermal spraying technique

    Publication Year: 2006 , Page(s): 2115 - 2120
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2764 KB) |  | HTML iconHTML  

    In this paper, the low temperature high velocity air fuel (LTHVAF) spraying technique was applied to prepare the alpha-Fe/epoxy resin nanocomposite coatings. The composite powders were mixed with different mass fractions, and the microstructure and reflectivity coefficient of coatings were tested. The results show that the microstructure of coatings is dense and low porosity; nano metal particles are dispersed in the coatings. The coatings are closely combined with substrate. In these coatings, the volume fraction calculated with density, component distribution, properties of metal particle, and coating thickness can affect the microwave absorption ability of the coatings. The reflectance coefficient of 70 mass% nano alpha-Fe/epoxy resin composite coatings is lower than others. In these nanocompsite absorber coatings, the relationship of the reflectivity coefficient and the coating structure were constructed with permittivity, permeability, and thickness. The optimal mass fraction of absorber coatings is about 0.3. It is analyzed with self-bonding strength and reflectivity coefficient. This means that the change of the coating structure affects the performance of the nanocomposite coatings View full abstract»

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  • Viscosity-based magnetodynamic model of soft magnetic materials

    Publication Year: 2006 , Page(s): 2121 - 2132
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (584 KB) |  | HTML iconHTML  

    A time-stepping method based on the concept of magnetic viscosity developed to reproduce the excess loss in electrical steel is proposed. A numerical scheme for simultaneous solution of Maxwell equations and equations describing the magnetic viscosity has been developed. The method is suitable for describing arbitrary magnetization regimes such as waveforms associated with pulsewidth modulation (PWM) voltage excitation, and the model differential equations can be conveniently combined with equations of an external electric circuit. The accuracy of the proposed dynamic model is shown using three nonoriented electrical steel as examples. Fitting of the magnetic viscosity parameters for one sinusoidal flux regime enables dynamic hysteresis loops and losses to be predicted with high accuracy over a wide range of frequencies and amplitudes of sinusoidal or nonsinusoidal flux densities View full abstract»

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  • Theoretical modeling and experimental tests of an electromagnetic fluid transportation system driven by a linear induction motor

    Publication Year: 2006 , Page(s): 2133 - 2151
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3274 KB) |  | HTML iconHTML  

    We report on a theoretical and experimental study of the use of a traveling magnetic field generated by a linear induction motor to propel a conducting fluid in a closed channel. We initially developed an analytical model to predict the distribution of density currents, forces, and fluid speed. To verify the validity of our assumptions for the analytical model, we developed a finite-element model and compared its results to those ones obtained from the analytical model. We built a prototype of the fluid transportation system, using mercury as the conducting fluid. Here, we present the prototype's experimental characteristics with various alternating current values and compare them with the analytical model's results View full abstract»

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  • Magnetic vector potential based model for eddy-current loss calculation in round-wire planar windings

    Publication Year: 2006 , Page(s): 2152 - 2158
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (602 KB) |  | HTML iconHTML  

    An analytical development of the magnetic vector potential is used to investigate the losses in round-wire planar windings. The current distribution in wires is affected by the skin effect and the field created by adjacent wires (proximity effect). This field depends on the current distribution in conductors, resulting in a closed-form problem. In this paper, we obtain the vector potential outside a conductor to estimate the effect of induced currents in the field shape over the neighboring conductors. We use the results to calculate the losses in planar windings such as those in domestic induction heaters. We obtain an equivalent resistance representing the losses in windings and compare it with measurements. This solution provides an accurate analytical approach to modeling the losses in close-packed windings View full abstract»

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  • A comparison of single-layer coaxial coil mutual inductance calculations using finite-element and tabulated methods

    Publication Year: 2006 , Page(s): 2159 - 2163
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (821 KB) |  | HTML iconHTML  

    Quick and accurate methods to calculate the mutual inductance of coaxial single layer coils remains important to this day in a large variety of engineering and physical disciplines. While modern finite-element electromagnetic field codes can do this accurately, the engineer often requires only a first- or second-order estimate before proceeding to the numerical analysis stage. Grover's tabular data, developed in the first half of the 20th century, remains the standard for manually calculating mutual inductance for a wide variety of coil and wire forms. This investigation reports the accuracy of mutual inductance calculations for single-layer coaxial coils based on Grover's tables when compared to estimates obtained with a finite-element electromagnetic field code (FEEFC). Since it is impractical to construct and characterize the numerous coils needed for this type of investigation, the FEEFC results are treated as actual inductance measurements. Grover reported his tabular data to be accurate within five significant digits excluding the cases when the coils are loosely coupled and when the coils are short. This investigation found Grover's tabular method to be inaccurate for loosely coupled and short coils, but also found that significant error for closely coupled coils as well. The maximum error between Grover's tabular method and the FEEFC results is 9.8%. Knowing the error associated with Grover's method and the coil geometry for which the error occurs is an important aid for the engineer and scientist View full abstract»

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  • Effects of numerical formulation on magnetic field computation using meshless methods

    Publication Year: 2006 , Page(s): 2164 - 2171
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1710 KB) |  | HTML iconHTML  

    Meshless methods have some advantages over their counterparts such as the finite-element method (FEM). However, existing meshless methods for computational electromagnetic fields are still not as efficient as FEM. In this paper, we compare two meshless methods of discretizing the computational domain of Poisson-like problems; namely, the point collocation and Galerkin methods (which use the strong and weak forms of the governing equation respectively), and their effects on the computational accuracy and efficiency of the magnetic fields. We also discuss methods of handling discontinuities at the material interface. We present several examples, which also provide a means to validate and evaluate both meshless methods. Exact solutions and/or FEM are used as a basis for comparison. In addition, we also verify the results by comparing computed magnetic forces against those measured experimentally View full abstract»

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  • Reciprocating flux-concentrated induction generator for free-piston generator

    Publication Year: 2006 , Page(s): 2172 - 2178
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2009 KB) |  | HTML iconHTML  

    This paper presents and examines a self-excited tubular induction generator for a free-piston generator system. The induction generator utilizes flux concentration by eddy currents. The paper shows that leakage flux is thereby reduced in the proposed generator and its performance is greatly improved. A three-dimensional finite-element method is employed to investigate its performance. A comparison of the calculated and measured results for standstill thrust force confirms the validity of the model View full abstract»

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  • Design and performance of permanent-magnet DC linear motors

    Publication Year: 2006 , Page(s): 2179 - 2183
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2044 KB) |  | HTML iconHTML  

    Energy-efficient direct linear electric drives are gaining increased attention as a result of continuous developments in high-energy permanent magnets and advances in power electronics and microcontrollers. This paper presents a step-by-step approach to the design of permanent-magnet dc linear motors (PMDCLMs). The problems of armature reaction and saturation of the permeable members of the motor lead to a nonlinear and asymmetric air-gap magnetic flux density as a function of position and, consequently, the static thrust versus position characteristics of PMDCLMs. The paper describes a prototype PMDCLM that reveals these phenomena and presents design concepts aimed at alleviating these problems View full abstract»

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  • Fast finite-element solver for a reluctance mass accelerator

    Publication Year: 2006 , Page(s): 2184 - 2192
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (729 KB) |  | HTML iconHTML  

    By choosing an appropriate method for partitioning and linearizing the system equations that describe a time-domain finite-element model of a reluctance mass accelerator, it is possible to reduce the computation time considerably over a traditional material reluctance model. In this work, we have constructed an axisymmetric magnetic field finite-element solver based on the induced magnetization of the saturable materials, instead of the more common field-dependent reluctance model. Eddy currents and driving circuit elements are also included in the model. Using this platform, we demonstrate how a well-conditioned set of field equations is produced and how a simple nonlinear iteration scheme can produce reliable results without repeated factorization of the finite-element matrix. Some comparisons with an established simplified model and experimental results help to verify the model View full abstract»

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  • Mechanisms for the longitudinal recoil force in railguns based on the Lorentz force law

    Publication Year: 2006 , Page(s): 2193 - 2195
    Cited by:  Papers (2)
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    In this paper, the electric induction force due to a time-varying current is used to account for the longitudinal recoil force exerted on the rails of railgun accelerators. The analysis is based on the Lorentz force law. The paper shows that the induction force is longitudinal to the rails, and that its magnitude depends on the location, speed, and acceleration of the armature, and can be the strongest at the heads of the rails as observed in experiments View full abstract»

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  • Magnetic circuit for a controllable reactor

    Publication Year: 2006 , Page(s): 2196 - 2200
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (430 KB) |  | HTML iconHTML  

    Reactive power compensation is vital for obtaining efficient operation of long transmission power lines or cables. A controllable shunt reactor that controls the transmission of power by continuous reactive power compensation will reduce the transmission losses and increase the transmission capacity of active power. We show that the saturation phenomena of iron and the high current density of a high-temperature superconductor can be utilized to design controllable reactors with large dynamic range, low losses, and limited harmonic distortion. We have designed and constructed a small-scale prototype of a controllable shunt reactor with a high-temperature superconductor control winding. We present a simple model of the magnetic circuit of the controllable reactor and we compare calculations from the model to experimental measurements on the controllable reactor View full abstract»

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  • Three-phase electromagnetic filter for zero-sequence harmonics

    Publication Year: 2006 , Page(s): 2201 - 2207
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (708 KB) |  | HTML iconHTML  

    This paper proposes a shunt electromagnetic filter to attenuate zero-sequence harmonic injection into three-phase star-grounded supplies. The device is built on the basis of zigzag windings and a three-leg core-type magnetic arrangement. Physical considerations as well as mathematical modeling and computer implementation are fully described. The paper reports on computational investigations to verify the filter performance under balanced and unbalanced supply voltages and on laboratory validation of a prototype device. Both the modeling and the laboratory results are in close agreement and demonstrate the capacity of the equipment to filter the components of the zero-sequence currents. The product performance in a real system is also included in the analysis. The theoretical and practical studies show that the level of zero-sequence harmonic injected into the mains can be reduced by 80% or more, depending on the control of filter leakage inductance. This method also leads to cheaper, simpler, and more robust equipment View full abstract»

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  • Field distributions around arbitrary shape surface cracks in metals, induced by high-frequency alternating-current-carrying wires of arbitrary shape

    Publication Year: 2006 , Page(s): 2208 - 2214
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (440 KB) |  | HTML iconHTML  

    We propose an efficient modeling technique for theoretical prediction of magnetic field distributions around an arbitrary shape surface-breaking crack in a metal, induced by an alternating-current-carrying wire of arbitrary shape. The finite-difference method is first used to solve the governing Laplace equation inside the crack region. The normal component of magnetic field at the crack opening is thus obtained to derive a closed-form solution in the Fourier domain for the regions outside the crack. To support the validity of the model, we compare experimental results with their theoretical counterparts View full abstract»

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  • Role of bottom layer of double recording layer structure for antiferromagnetically coupled longitudinal media

    Publication Year: 2006 , Page(s): 2215 - 2217
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    Double recording layers stacked on a Ru spacing layer are commonly used to obtain good recording properties for antiferromagnetically coupled (AFC) longitudinal media. In this paper, we report on a study that clarified the role of the bottom recording layer (BRL). We measured physical magnetic properties such as magnetic anisotropy field (Hk ), magnetocrystalline anisotropy energy (Ku), intergranular interaction, and thermal agitation of the AFC media, with and without BRL. Results showed that: 1) even a thin BRL (1 nm thick) significantly increases remanent coercivity Hcr; 2) this increase in Hcr is mainly caused by an increase in Hk due to elimination of the low Ku region at the bottom portion of the top recording layer; and 3) judging from magnetic cluster size, insertion of a BRL can reduce the intergranular exchange coupling at the initial growth region of the recording layer View full abstract»

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  • Information rates of multidimensional front ends for digital storage channels with data-dependent transition noise

    Publication Year: 2006 , Page(s): 2218 - 2228
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (925 KB) |  | HTML iconHTML  

    This paper presents a simulation-based method for the computation of the information rates of recently proposed multidimensional front ends for digital storage channels with transition noise. First, we propose an algorithm, based on linear prediction and state reduction techniques, that extends recent work on the information rates of magnetic recording channels affected by colored Gaussian thermal noise, intersymbol interference, and signal-dependent transition noise. Following a previous study on statistical sufficiency, we apply this algorithm to compute the information rates of digital storage systems featuring a multidimensional detection front end. The resulting information rates indicate that significant gains may be achievable by multidimensional signal processing techniques in transition-noise-limited digital storage channels View full abstract»

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  • IEEE Magnetics Society Information

    Publication Year: 2006 , Page(s): c3
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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