By Topic

Magnetics, IEEE Transactions on

Issue 5 • Date Sept. 2003

Filter Results

Displaying Results 1 - 10 of 10
  • High-response inductive electromagnetic sensor

    Page(s): 2190 - 2193
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (315 KB) |  | HTML iconHTML  

    A high-response inductive electromagnetic sensor can be made by arranging a conductive and/or magnetic material between the primary coil and the secondary coil. Compared with the conventional inductive electromagnetic sensor, the new sensor has a larger responsivity index (used here to evaluate its characteristics), though it also has a smaller induced voltage at the secondary coil. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Computing Maxwell eigenvalues by using higher order edge elements in three dimensions

    Page(s): 2149 - 2153
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (429 KB) |  | HTML iconHTML  

    We use recently proposed hierarchic basis functions and a tetrahedral partitioning to compute Maxwell eigenvalues on a bounded polygonal domain in R3, using a p-version finite-element procedure based on edge elements. The problem formulation requires a set of basis functions that are H(curl)-conforming and another compatible set that is H1-conforming. In this preliminary study, we employ a uniform order of approximation throughout the domain. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Measuring the permeability of stressed steel by the magnetomotive-force-vane method with magnetization perpendicular to the surface

    Page(s): 2179 - 2189
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (567 KB) |  | HTML iconHTML  

    This paper describes a new method of measuring some magnetic properties of steel under applied biaxial stresses in the x-y plane when the steel is magnetized in the z direction (called "z magnetization"). Results are compared with two other sets of experimental data. The conclusions are that z magnetization is prone to several sources of error of significant amounts, whichever technique is used, and that these errors must be reduced if the small changes in magnetic properties predicted by the theory are to be reliably verified. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Worst case tolerance design of magnetic devices by evolutionary algorithms

    Page(s): 2170 - 2178
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (431 KB) |  | HTML iconHTML  

    This paper presents an evolutionary approach to worst case tolerance design of magnetic devices. The algorithm improves on the classical nominal design, accounting for parameter variations and tolerances, so that the system performance does not exceed upper and lower specifications imposed in advance by the designer. The evolutionary algorithm adjusts central values and tolerances of parameters so that a user-defined objective function is optimized and the design constraints are met. The feasibility of the candidate sets of design parameters and tolerances is estimated by means of vertex analysis. The algorithm ensures that the optimized design set of parameters and tolerances is 100% feasible in a large number of practical cases. This paper gives an example of the design of a magnetic device and discusses the salient features and limitations of the approach. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Hybrid genetic algorithm for electromagnetic topology optimization

    Page(s): 2163 - 2169
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (599 KB) |  | HTML iconHTML  

    This paper proposes a hybrid genetic algorithm (GA) for electromagnetic topology optimization. A two-dimensional (2-D) encoding technique, which considers the geometrical topology, is first applied to electromagnetics. Then, a 2-D geographic crossover is used as the crossover operator. A novel local optimization algorithm, called the on/off sensitivity method, hybridized with the 2-D encoded GA, improves the convergence characteristics. The algorithm was verified by applying it to various case studies, and the results are presented herein. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Magnetic design optimization and objective function approximation

    Page(s): 2154 - 2162
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1336 KB) |  | HTML iconHTML  

    This paper addresses the problem of optimizing a device by using an interpolation of the objective function. Optimization by means of stochastic methods can explore the objective function and give reliable indications on its global extrema, but the number of function calls can be unacceptably large when numerically evaluated functions are used. An optimization procedure applied not directly on the objective function but on its interpolation can significantly reduce the cost of the optimization. An efficient coupling between interpolation technique and optimization method is needed both to explore features of the optimization algorithm and to exploit advantages of the interpolation. This paper analyzes the performance of a multiquadric interpolation procedure on analytical functions and on finite-element evaluations. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Nanoscale structure and magnetic properties of Nd-Fe-Nb-B-C permanent magnets

    Page(s): 2194 - 2197
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (510 KB) |  | HTML iconHTML  

    We investigated the nanoscale structure and magnetic properties of Nd2(FeNb)14(BC)/α-Fe. We studied several alloy compositions and the effect of C and Nb on the properties, and thus produced a new alloy of Nd9Fe85.5Nb1.0B4C0.5. Its mean grain size is about 40 nm. Grain refinement enhanced the remanence, because of greater ferromagnetic exchange coupling between the hard and soft magnetic phase grains. Annealing improved the properties further. By optimizing the processing conditions, we obtained relatively high performance [Jr=1.099 T, Hci=518.3 kA/m, Jr/Js=0.82, (BH)max=137.8 kJ/m3] when the alloy was annealed at 700°C for 15 min. We examined the magnetic domain structure in the nanophase alloy by magnetic force microscopy. The length of the magnetic contrast in the alloy is in the range of 450-550 nm, much bigger than the mean grain size. Here, we interpret the length in terms of interaction domains, which originate from the exchange coupling effect. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Magnetostatic energy of structures with rotating vector magnetizations

    Page(s): 2146 - 2148
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (387 KB) |  | HTML iconHTML  

    We show that, no matter which of two methods of calculating the change in magnetostatic energy is used, there is no change in energy when a hollow cylinder with a one-sided flux, rotating vector magnetization is placed in a uniform magnetic field. Similarly, there is no energy change when a planar one-sided flux structure is exposed to a uniform field. Only one case has been found where a one-sided flux, spherical structure shows no such energy change. We show this phenomenon to be a result of the rotating magnetization and not a property of one-sided flux structures. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Ultrathin amorphous carbon overcoats by filtered cathodic arc deposition

    Page(s): 2201 - 2204
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (227 KB) |  | HTML iconHTML  

    We studied properties of 2- to 25-nm-thick tetrahedral amorphous carbon films produced by filtered cathodic arc deposition. We found that nitrogen doping was effective in controlling film properties. Both the amount of sp3 bonding in the film and the hardness decreased with nitrogen incorporation. The adhesion of lubricant to the carbon film was improved by nitrogen doping. Tests of wear and corrosion on a nanometer scale showed the superior tribological and anticorrosion performance of tetrahedral amorphous carbon films over hydrogenated amorphous carbon films. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Magnetic properties and morphology of block copolymer templated ferrimagnetic CoFe2O4 nanoparticles

    Page(s): 2198 - 2200
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (353 KB) |  | HTML iconHTML  

    We synthesized the block copolymer of poly(norbornene-dicarboxcylic acid) and poly(norbornene) at room temperature, using ring opening metathesis polymerization. We then templated the CoFe2O4 nanoparticles within the polymer matrix, utilizing the self-assembled nature of the block copolymer. We used transmission electron microscopy, superconducting quantum interference device magnetometry, and X-ray powder diffraction to investigate the morphology and magnetic properties of the nanocomposites. The nanocomposite films are ferrimagnetic at room temperature. The CoFe2O4 nanoparticles are spherical and have an average radius of 8.7±0.4 nm. The nanoparticles are uniformly distributed within the polymer matrix with a nanoparticle density of 1109 particles/cm2. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

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.

Full Aims & Scope

Meet Our Editors

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