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Magnetics, IEEE Transactions on

Issue 2 • Date March 1982

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Displaying Results 1 - 25 of 104
  • [Front cover and table of contents]

    Publication Year: 1982 , Page(s): 0
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    Freely Available from IEEE
  • Welcoming remarks

    Publication Year: 1982 , Page(s): 315
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    Freely Available from IEEE
  • The trials, tribulations, and thrills of setting up and operating a one-person computer job shop for calculating magnetics fields and other sundry things

    Publication Year: 1982 , Page(s): 316 - 318
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    A brief history of job shops since the caveman era is surveyed, and the essential elements of a job shop are found to be: to earn your living performing a useful service, or creating a useful object, for your contemporaries. The complexities of setting up a computer job shop are described. Inspection of a symbolic floor plan of the shop shows a Program Development, Installation, and Repair Lab that operates with the well-known pitfalls and traps that occur when a real live person interacts with a large, stupid computer. The Output Assembly and Analysis Lab is the holding area where up to N projects are worked on simultaneously. On the main floor of the shop resides the program load modules, some of which are described in detail. Separate from the main shop area is the Remote Job Entry Lab, affectionately called the Physics Group Zoo. The creatures that dwell there are also described to illustrate the difficulty in data preparation and job submission. In spite of all these adversities, the thrill of solving complex problems makes it all worthwhile. View full abstract»

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  • Complementary and dual energy finite element principles in magnetostatics

    Publication Year: 1982 , Page(s): 319 - 324
    Cited by:  Papers (23)
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    A method of providing bounded solutions to a wide range of magnetostatic field problems is outlined. The method extends complementary and dual energy variational principles to encompass the T-Ω formulation of electromagnetic field problems and shows how this leads to efficient finite element implementation of the technique. Examples are given that show clearly the bounded nature of the procedure, and indicate how it may be used to reduce the computational requirements necessary for a specific accuracy of solution. View full abstract»

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  • Direct finite element analysis of flux and current distributions under specified conditions

    Publication Year: 1982 , Page(s): 325 - 330
    Cited by:  Papers (70)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (608 KB)  

    When the flux distribution of a magnetic circuit is analyzed by using the conventional finite element method, the magnetizing currents must be given. Therefore, if the flux distribution is specified, it is difficult to obtain the distributions of magnetomotive forces or configuration of magnets producing the specified field distribution by the conventional finite element method. New methods which are called the "finite element method taking account of external power source" and the "finite element method with shape modification" have been developed. The processes of calculation in these methods are contrary to the conventional technique. These new methods have the following advantages: (a) If there are many unknown independent magnetizing currents, these currents are directly calculated by the new method. (b) When a flux distribution is specified, the optimum shapes of the magnets can be directly calculated. (c) As these new methods need no repetition, computing time can be considerably reduced. The principles and the finite element formulations of these new methods are described, and a few examples of application of these methods are shown. These new methods make it possible to design the optimum magnetic circuits by using the finite element method. View full abstract»

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  • Accurate field computation with the boundary element method

    Publication Year: 1982 , Page(s): 331 - 335
    Cited by:  Papers (19)
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    Interface problems in magnetostatics are formulated as boundary integral equations of the second kind involving the appropriate scalar (no current sources) or vector potentials. The boundary element method (BEM), which employs parametric representation of surfaces and sources, is used to solve some two-dimensional examples by way of illustration. A novel approach, automated to address Green's functions singularities over arbitrarily-shaped geometries, is introduced. View full abstract»

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  • On the coupled differential-integral equations for the solution of the general magnetostatic problem

    Publication Year: 1982 , Page(s): 336 - 339
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (376 KB)  

    The paper discusses some coupled differential-integral formulations of the magnetostatic problem. These formulations are derived from the original integral equation. Their main features are differential equations inside the iron; and an integral equation on the iron boundary, that is coupled with the differential equations. An application of perturbation estimates is illustrated. Preliminary computational results support our belief that the methodology described is functional. View full abstract»

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  • An integral-equation/singularity-method approach for 3-D electromagnetic field determination in the end region of a turbine-generator

    Publication Year: 1982 , Page(s): 340 - 345
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (576 KB)  

    A mathematical model using an integral-equation/singularity-method approach is derived for determining the magnetic field and electromagnetic forces induced by current-carrying conductors in a region bounded by 3-D material-body surfaces which have complex configurations. Special analytical and numerical techniques that eliminate near-field computational difficulties and bypass the cumbersome matrix manipulations required by other integral-equation approaches are described. A comprehensive computer program package has been developed using this approach for obtaining the 3-D solutions in the end region of a turbine-generator due to armature end windings. Special computational techniques for handling the complex end-winding and surface geometry are described and detailed numerical results are presented for the 3-D field solution and the forces acting on the conductors. View full abstract»

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  • Solution of three-dimensional, anisotropic, nonlinear problems of magnetostatics using two scalar potentials, finite and infinite multipolar elements and automatic mesh generation

    Publication Year: 1982 , Page(s): 346 - 350
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (496 KB)  

    The two-scalar potentials idea has been used with success for the computation of static magnetic fields in the presence of nonlinear isotropic magnetic materials by the finite element method. In this communication we formulate the two-scalar-potentials method for anisotropic materials and present a computer program and the solution of an example problem. The use of infinite multipolar elements is also discussed. Several advanced methods and ideas are employed by the program: scalar potentials, rather than vector potentials, giving only one unknown quantity; the finite element method, in which the solution is approximated by a continuous function; the Galerkin method to solve the differential equations; accurate infinite elements, which avoid the introduction of an artificial boundary for unbounded problems; automatic mesh generation, which means that the user can construct a large mesh and represent a complicated geometry with little effort; automatic elimination of nodes outside the iron, which restricts the iterations to the nonlinear anisotropic region with economy of computer time; use of sparse matrix technology, which represents a further economy in computer time when assembling the linear equations and solving them by either Gauss elimination or iterative techniques such as the conjugated gradient method, etc. The combination of these techniques is very convenient. View full abstract»

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  • A microprocessor based electromagnetic field analysis system

    Publication Year: 1982 , Page(s): 351 - 356
    Cited by:  Papers (1)
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    The construction of an interactive finite element analysis system is described. First the components of the finite element software are considered. Second, the advantages of dedicated single user workstations are discussed. An example is given of a complete system implemented on a microprocessor based workstation. View full abstract»

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  • A new computational approach for the linearized scalar potential formulation of the magnetostatic field problem

    Publication Year: 1982 , Page(s): 357 - 361
    Cited by:  Papers (1)
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    We consider the linearized scalar potential formulation of the magnetostatic field problem in this paper. Our approach involves a reformulation of the continuous problem as a parametric boundary problem. By the introduction of a spherical interface and the use of spherical harmonics, the infinite boundary condition can also be satisfied in the parametric framework. The reformulated problem is discretized by finite element techniques and a discrete parametric problem is solved by conjugate gradient iteration. This approach decouples the problem in that only standard Neumann type elliptic finite element systems on separate bounded domains need be solved. The boundary conditions at infinity and the interface conditions are satisfied during the boundary parametric iteration. View full abstract»

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  • A space charge beam option for the PE2D and TOSCA packages

    Publication Year: 1982 , Page(s): 362 - 366
    Cited by:  Papers (1)
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    An outline is given of the further development of the PE2D finite element package to take account of space charge forces in particle trajectory plotting. Extension to 3D using the TOSCA package is also discussed. View full abstract»

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  • Alternative vector potential formulations of 3-D magnetostatic field problems

    Publication Year: 1982 , Page(s): 367 - 372
    Cited by:  Papers (22)
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    A unified theory of three-dimensional vector potential formulations of magnetostatic field problems is presented. It is shown that existing formulations are based on one of two equivalent boundary value problems. A new formulation is derived, using the concept of projection between the space of arbitrary vector finite elements and the space of non-divergent vector finite elements. The merits of the different approaches are examined. View full abstract»

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  • Computation of magnetostatic fields in three-dimensions based on Fredholm integral equations

    Publication Year: 1982 , Page(s): 373 - 378
    Cited by:  Papers (15)
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    An integral equation method is described for solving three-dimensional magnetostatic problems involving linear permeability interfaces and current sources. The interface is replaced by magnetic charges in free space to provide an equivalent interface condition. Application has been made to leakage field calculations in transformers. Numerical methods are combinations of analytical formulas and numerical integration; basis functions approximate the charge distribution. View full abstract»

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  • A point-iterative algorithm for three-dimensional magnetic vector problems

    Publication Year: 1982 , Page(s): 379 - 384
    Cited by:  Papers (1)
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    Magnetostatic field problems are solved in three dimensions by applying a variational method that employs finite elements. Formulation through a partial differential equation allows solution for the magnetic vector potential given an inhomogeneous, orthotropic medium and a distributed current source. Three vector boundary conditions are discussed and interior sheet currents are allowed within the medium. In addition, the Lorentz condition is enforced by including a penalty term in the energy functional. A point-iterative algorithm is used to solve the set of equations resulting from finite element discretization. This method is particularily suitable for regions with regular geometry and a moderate (1,000 to 10,000) number of unknowns. View full abstract»

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  • Synthesis of magnetic fields

    Publication Year: 1982 , Page(s): 385 - 390
    Cited by:  Papers (7)
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    The paper deals with some problems of magnetic fields synthesis, depending on determination of the current density distribution, which generates the required magnetic field in the investigated region. Such problems can be reduced to the linear, or nonlinear Fredholm integral equations of the first kind, or to the set of these equations. Fredholm integral equation of the first kind belongs to the class of the ill-posed problems, and for its solving the method of regularisation has been used. In the paper there are given some useful results of synthesis of magnetic fields in few practical configurations. View full abstract»

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  • The fixed point theorem in computing magnetostatic fields in a nonlinear medium

    Publication Year: 1982 , Page(s): 391 - 392
    Cited by:  Papers (1)
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    In the paper, a concept of a new method for computing reluctivity distribution in the nonlinear media using Brouwer's fixed point theorem is presented. View full abstract»

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  • Iterative algorithm for magnetostatic problems with saturable media

    Publication Year: 1982 , Page(s): 393 - 396
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    This paper presents an iterative algorithm for computing a static magnetic field in an unbounded region in which the medium is saturable. An analysis is presented that shows the algorithm converges to the correct answer for all starting conditions. View full abstract»

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  • Magnetostatic field calculations associated with superconducting coils in the presence of magnetic material

    Publication Year: 1982 , Page(s): 397 - 400
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    A brief account is given of relevant magnetostatic field calculations in iron-free systems concerning the uniformity of the field produced by current-carrying axi-symmetric conductors. The effects of iron on the uniformity of the field produced by such a conductor are then considered. Using a perturbation analysis a simple analytic expression is obtained which describes the field close to the axis of symmetry. Some of the advantages of this method over traditional finite-difference methods are noted. View full abstract»

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  • A comparison of integral and differential equation solutions for field problems

    Publication Year: 1982 , Page(s): 401 - 405
    Cited by:  Papers (14)
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    Field computation in three dimensions is necessarily expensive. To minimise the cost and increase the reliability of the results it is important to use well behaved formulations. Several integral equation formulations are shown and their conditioning is examined, point matching and weighted residual solutions are compared. Finally the integral methods are compared with finite element solutions of partial differential equations. The applicability of the two approaches is discussed in relation to the development of new computer hardware and costs. View full abstract»

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  • NMLMAP-A two dimensional finite element program for transient or static, linear or nonlinear magnetic field problems

    Publication Year: 1982 , Page(s): 406 - 410
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB)  

    NMLMAP is a finite element program for the solution of two dimensional magnetic field problems. The problems may be transient or static, linear or nonlinear, and planar or axisymmetric. The program has features that include a coarse-to-fine rezone technique; an adaptive acceleration method for speeding the convergence of the nonlinear iteration; and a substructuring technique for decreasing solution times in certain non-linear problems. These features, the governing and finite element equations, and example problems are discussed View full abstract»

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  • The PE2D package for transient eddy current analysis

    Publication Year: 1982 , Page(s): 411 - 415
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (448 KB)  

    The PE2D package is a suite of programs for solving, by the finite element method, the electro-magnetic and electrostatic problems which are described by the Laplace, Poisson, Helmholtz or diffusion equation in two dimensions. This paper describes the package and illustrates its use in solving transient eddy-current problems. View full abstract»

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  • Applications and further developments of the eddy current program EDDYNET

    Publication Year: 1982 , Page(s): 416 - 421
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (544 KB)  

    EDDYNET is a computer code for solving eddy current problems using an integral equation method and a network (wire mesh) approach. The code can be applied to infinitely long prisms, thin plates, and thin shell. Preliminary results with a three-dimensional version are described. Application to a tokamak limiter experiencing a plasma disruption is also described. View full abstract»

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  • A network mesh method to calculate eddy currents on conducting surfaces

    Publication Year: 1982 , Page(s): 422 - 425
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (472 KB)  

    This report describes a network mesh analysis technique which can be used to calculate transient or steady-state eddy current distributions on a conducting surface. In general, the surface may have any continuous three-dimensional shape, may vary in surface resistivity, and may include holes. The surface is divided into a network of branches for each of which are calculated a resistance, a self-inductance, and a set of mutual inductances to all other branches. The resulting branch resistance and branch inductance matrices are transformed into mesh matrices using a conventional network procedure. A set of simultaneous differential equations can then be established to solve for eddy currents. The set of equations is generally solved for a time series of eddy currents caused by an external source of excitation. Various initial conditions can be used to find other solutions of interest such as the self decay of an arbitrary current distribution. Great simplification is possible by imposing boundary conditions to take advantage of symmetry. In addition, the set of equations needs to be solved one time only for the special cases of pure inductance, pure resistance, or steady-state. View full abstract»

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  • Eddy current calculation in 3D using the finite element method

    Publication Year: 1982 , Page(s): 426 - 430
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (368 KB)  

    A vector potential A and an electrical scalar potential φ are taken to describe the three dimensional eddy current problem. A finite element equation system is set up for a non magnetic region using the Galerkin method. The scalar potential φ is eliminated from the equation system in order to reduce the number of unknowns per node. Time dependent solutions for potentials and eddy currents can be obtained using a step by step procedure. 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.

Full Aims & Scope

Meet Our Editors

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