International Journal of Applied Electromagnetics and Mechanics

In this paper an automated multiobjective optimisation based on fuzzy logic is applied to the magnetic core design of induction machines. The fuzzy logic is used in order to merge all the objectives of the vector optimisation in a single scalar function, so that the problem can be handled through a scalar optimisation algorithm. The estimation of the objectives is obtained through the field analysis performed by the Finite Element Method (FEM). The proposed procedure is used to improve performances of industrial induction motors where iron losses, electromotive forces and weight are optimisation objectives, while airgap thickness, external stator radius and stator tooth width are considered as design parameters.

The coupled electromagnetic, thermal and elastic–plastic field simulation is described for new technological processes of multi‐impulse inductive heating of metal. An iterative algorithm, taking into account the special features of multi‐impulse inductive heating, has been developed. The algorithm consists in the solution of the eddy current problem for one impulse and in the extension of the obtained distribution to a number of next impulses. Thermal and mechanical fields are determined for a series of the impulses using the increased value of the time step and the time average distribution of the heat sources. This paper presents the detailed description of the numerical technique and of the obtained results concerning real technological processes.

This paper is concerned with the development of a soft palpation sensor for detection of prostatic cancer and hypertrophy. The sensor is a layered medium with two polyvinylidene fluoride (PVDF) films embedded in the matrix sponge rubber. It is pressed against the prostates and the output voltage signals from the polymer films are measured. The temporal mean values, {I}_1 and {I}_2 , of absolute voltage signals from the films are calculated and their ratio {I}_1/{I}_2 is used as the sensor output. First, the fundamental characteristics of a rectangular sensor with a plane surface are examined. Then, the surface geometry of the sensor was designed so that it clearly indicates the nature on the stiffness of the soft material. Finally, a compact cylindrical sensor attached to the doctor’s forefinger is described and experimental studies of its performance as a palpation sensor are presented. Some representative clinical data on the normal and hardened prostate glands are also presented.

The diffraction of an electromagnetic plane wave by a perfectly conducting strip in a biisotropic medium is considered. The problem is solved by using the Wiener–Hopf technique and the asymptotic methods. The diffracted field is shown to be the sum of a field produced by the two edges of the strip and a field due to the interaction of the two edges.

An inverse problem concerning the industrial process of steel bars hardening is considered. The associated optimization problem is formulated in terms of normalized membership functions and, for the sake of comparison, also in terms of quadratic residuals; both geometric and electromagnetic design variables have been considered. The numerical solution is achieved by coupling an electrothermal field simulator to a deterministic strategy of minimization.

The combination of Genetic Algorithms (GAs) and Artificial Neural Networks (ANNs) has already resulted in researchers advancing in quite a few real world applications but it is in control that this alliance yields such appreciable benefit.

The paper reports a Radial Basis Function (RBF) network training technique which joins together global strategy of GAs and a local adjusting procedure typical for RBF networks. While activation function window centres and widths are processed via a “slow” numeric GA, output‐layer neurone synaptic weights are defined by a “fast” analytical method.

The technique allows to minimize not only the network hidden-layer size but also the pattern set required for training the adequate dynamical object neuroemulator.

A large number of methods for the design optimization have been proposed in recent years. However, it is not easy to apply these methods to practical use because of many iterations. So, in the design optimization, physical and engineering investigation of the given model are very important, which results in an overall increase in the optimization speed.

This paper describes a novel optimization procedure utilizing the conformal transformation method. This approach consists of two phases and has the advantage of grasping the physical phenomena of the model easily. Some numerical results that demonstrate the validity of the proposed method are also presented.

Cheng obtained the electromagnetic fields radiated by a time-varying source in a homogeneous chiral material, but the results are unphysical because the essentially dispersive nature of chiral materials was totally ignored in the analysis.

I acknowledge this comment [A. Lakhtakia, Int. J. Appl. Electromagn. Mech. 9(1) (1998), 89] and add that the original results [D. Cheng, Int. J. Appl. Electromagn. Mech. 8(2) (1997), 179], which treat the purely instantaneous response, are only useful for a chiral medium when it can be approximately considered to be nondispersive under certain specified conditions.