International Journal of Applied Electromagnetics and Mechanics - Volume 9, issue 3

Authors: Gottvald, Aleš

Article Type: Editorial

DOI: 10.3233/JAEM-1998-122

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 9, no. 3, pp. 225-226, 1998

Authors: Ramirez, J.A. | Freeman, E.M.

Article Type: Research Article

Abstract: This work is concerned with the automatic design of electromagnetic devices in 3D using numerical methods, i.e., deterministic methods coupled with finite elements (FE). In particular this work considers the choice of deterministic methods, limitations concerning the number of variables, convergence, CPU time and choice of potentials for the field analysis. Two different approaches are considered for the sensitivity analysis, the direct differentiation of the FE matrices and the adjoint variable method. The FE formulation uses the magnetic vector potential for domains with current densities and the scalar potential for domains in which current densities are not present. The results …of two static problems are presented. In general, the increase in the number of variables, from 2D to 3D, did not represent a major problem for the convergence of the methods studied. In terms of CPU time, the sequential quadratic programming method performed better than the augmented Lagrange multiplier method. Both sensitivity analysis methods investigated proved to require similar field calculations. Show more

DOI: 10.3233/JAEM-1998-099

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 9, no. 3, pp. 227-239, 1998

Authors: Dyck, Derek N. | Lowther, David A.

Article Type: Research Article

Abstract: This paper introduces a Response Surface Model (RSM) which is constructed using both the function value and its derivative (or gradient) at the sample points. The model is a version of Interpolating Moving Least Squares (IMLS) which is essentially quadratic interpolation in a multi-dimensional table of scattered sample points. The method is especially cost-effective for response surfaces in many dimensions (on the order of 10 variables). The method is tested on a speaker assembly design problem with seven design variables, and compared to a Multiquadric RSM.

DOI: 10.3233/JAEM-1998-100

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 9, no. 3, pp. 241-248, 1998

Authors: Kwak, In-gu | Byun, Jin-kyu | Park, Il-han | Hahn, Song-yop

Article Type: Research Article

Abstract: This paper presents a design sensitivity algorithm for temperature distribution control in induction heating problems which require electro-thermal analysis. The eddy current distribution is calculated with the electromagnetic 2D finite element procedure. The obtained eddy current becomes a heat source which determines the temperature distribution, which is also obtained by the thermal 2D finite element method. In this paper, the goal of the design is to have the uniform distribution of the temperature on a surface of heated metal. The positions of exciting coils are taken as design parameters. The steepest descent method is used as an optimization algorithm. For …the optimal design of an induction heating system, the design sensitivity is derived using the relation of two analysis system equations, and is applied to a numerical example. Show more

DOI: 10.3233/JAEM-1998-101

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 9, no. 3, pp. 249-261, 1998

Authors: Gizolme, O. | Thollon, F. | Clerc, G. | Rojat, G.

Article Type: Research Article

Abstract: This paper describes a shape optimization of a synchronous machine rotor to reduce torque ripples. The procedure of optimization is based on coupling a finite element 2D software and a genetic algorithm. One of the most important criteria for minimizing the torque ripple is the distribution of the flux density in the airgap of the machine. Therefore, in the first investigations, we search to minimize the harmonics’ rate of the flux density. The field analysis is done through the finite element method. Simplifying assumptions, involving material characteristic and geometrical domains, are made in order to limit computational time. Different objective …functions (taking into account flux density harmonics) used by the genetic algorithm for the optimization and different strategies of evolution are tested and some results are presented. One of these is used to calculate torque ripples by the finite element method. This result is compared with the initial torque and shows the improvement on the torque ripple. Show more

DOI: 10.3233/JAEM-1998-102

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 9, no. 3, pp. 263-275, 1998

Authors: Brown, Robert W. | Fujita, Hiroyuki | Shvartsman, Shmaryu M. | Thompson, Michael R. | Morich, Michael A. | Petropoulos, Labros S. | Srivastava, Vishnu C.

Article Type: Research Article

Abstract: An inverse procedure is developed and applied to the design of new short actively shielded main magnet coils and new radio frequency (rf) coils in Magnetic Resonance Imaging (MRI). The new main magnet system is found through the use of inverse functional methods on bundled, discrete solenoidal coil systems, following the design procedure of Thompson et al. (1994). An additional wire bundle placed at the center of the system is a novel feature of the design. Similar functional methods are combined with the method of moments for the design of new rf coils where an advantage of the procedure is …that it provides a computational technique for optimization of field uniformity, signal-to-noise, feeding, tuning, and impedance matching. Successful prototypes have been built for both of the new coil designs. Show more

DOI: 10.3233/JAEM-1998-103

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 9, no. 3, pp. 277-290, 1998

Authors: Rekanos, I.T. | Tsiboukis, T.D.

Article Type: Research Article

Abstract: The application of the generalised radial basis functions neural networks to the solution of inverse problems in electromagnetism is investigated. A training strategy for the implementation of such networks is presented. The attractive property of these networks to work as universal approximators and the simplicity of their training process is examined in two application problems. In the first problem the evaluation of the conductivity profile of a layered planar structure is performed after the inversion of the impedance of a circular air cored probe coil, of rectangular cross section, which is placed above the considered structure. The second problem involves …the introduction of the generalised radial basis functions to the estimation of geometrical parameters of inaccessible structures via a set of field or potential measurements. The results obtained from these applications illustrate the efficiency and accuracy of the estimation and generalisation abilities of the generalised radial basis functions networks. Show more

DOI: 10.3233/JAEM-1998-104

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 9, no. 3, pp. 291-302, 1998

Authors: Lysenko, L.I. | Omelyanenko, V.I. | Sergeev, S.A.

Article Type: Research Article

Abstract: The problem of globally optimizing linear synchronous motor (LSM) design parameters in order to minimize power consumption is of great practical interest to those involved in engineering MAGLEV trains. The paper describes an optimization technique based on a Parallel Genetic Algorithm in which separate subpopulations of possible solutions in the search space are interpreted not as demes but as individuals with the subpopulation-points co-ordinate matrices identified as the individual chromosome sets. The second exclusive detail of the algorithm results from using a deformed polyhedron method as a means of improving the algorithm ability to fine-tune the solution. The subpopulation points …are treated as polyhedron apices, after which search heuristics borrowed from the Nelder–Mead method are applied to polyhedrons to provide their adaptation. The developed algorithm was examined via a ten-dimensional multiextrema test function before being applied to the multicriteria problem of LSM optimization. In both cases, it has coped with the tasks quite successfully, and has improved on results reported earlier. The paper also explores the lower bound of a feasible domain in the LSM criteria space. Show more

DOI: 10.3233/JAEM-1998-105

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 9, no. 3, pp. 303-314, 1998

Authors: Alotto, P. | Brandstaetter, B. | Fuerntratt, G. | Magele, Ch. | Molinari, G. | Nervi, M. | Repetto, M. | Richter, K.R.

Article Type: Research Article

Abstract: The scope of this paper is to throw some light on the difficulties occurring when optimizing in a discrete parameter space. In the first section of this paper some general considerations on the optimization of a SMES device in a discrete space are made. In the second part a pattern search technique as a representative for deterministic, an evolution strategy and a simulated annealing algorithm as members of the class of stochastic methods are presented and used to optimize the problem. The effect of varying the discretization is investigated for the pattern search method. In the next section some features …of the benchmark problem are introduced and finally the optimization results are given. Show more

DOI: 10.3233/JAEM-1998-106

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 9, no. 3, pp. 315-324, 1998

Authors: Albanese, R. | Formisano, A. | Martone, R. | Morabito, F.C. | Rubinacci, G. | Villone, F.

Article Type: Research Article

Abstract: The application of a rotating field like that of induction machines is proposed for the eddy current testing of conducting cylindrical structures. This method allows for fast tracking of the position and geometrical parameters of cracks. In order to improve the capability to discriminate the depth of buried cracks, a suitable range of frequencies is considered. The measurement data are processed with a hybrid neuro-fuzzy system. Two artificial neural networks are used, one is specialized for surface cracks and the other one for buried cracks. The fuzzy system is used to perform the switching strategy between the two networks.

DOI: 10.3233/JAEM-1998-123

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 9, no. 3, pp. 325-338, 1998