International Journal of Applied Electromagnetics and Mechanics - Volume 29, issue 2

Authors: Primin, M. | Nedayvoda, I.

Article Type: Research Article

Abstract: This paper describes the development of the magnetostatic inverse problem solution methods for studies of the magnetic field of human heart (magnetocardiography – MCG). A set of N different dipole sources is associated with the spatial distribution of the heart magnetic field parameters, measured in the observation plane. Methods: Estimation of the field sources quantity in the heart for a given time-point of the average cardiocycle is obtained after spatial-and-time analysis of the spatial gradients …intensity of the magnetic field in the observation area (plane). Relative powers of the field sources have been obtained by plotting the Voronoi diagram. Mutual locations (coordinates) of the sources in the heart volume are obtained after examining the analytical solution of the magnetostatic inverse problem for each of the N magnetic dipoles. Results: The analytical solution of the magnetostatic inverse problem for several magnetic field sources, independently distributed in a 3D volume, has been obtained. The validity of the problem solution is supported by the results of numerical and physical simulations. Conclusions: Algorithm of the magnetostatic inverse problem solution is implemented as a software package for the magnetocardiograph and used for cardiology diagnosis. Show more

Keywords: Magnetic field, inverse problem solution, magnetocardiography, SQUID

DOI: 10.3233/JAE-2009-1001

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 29, no. 2, pp. 65-81, 2009

Authors: Hou, Peng-Fei | Yi, Tao | Leung, Andrew Y.T.

Article Type: Research Article

Abstract: We use the compact harmonic general solutions of transversely isotropic electro-magneto-thermo-elastic material to construct the three-dimensional Green's function for a steady point heat source acted in the interior of a semi-infinite transversely isotropic electro-magneto-thermo-elastic material by five newly introduced harmonic functions. All components of coupled field are expressed in terms of elementary functions and are convenient to use. Numerical results are given graphically by contours.

Keywords: Green's function, point heat source, semi-infinite, transversely isotropic, electro-magneto-thermo-elastic

DOI: 10.3233/JAE-2009-1003

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 29, no. 2, pp. 83-100, 2009

Authors: Yang, Zengtao | Yang, Jiashi

Article Type: Research Article

Abstract: We study anti-plane or shear horizontal piezoelectric waves propagating along the interface between two semi-infinite half-spaces of polarized ceramics with consideration of the effects of electric field gradient. An equation that determines the dispersion relations is obtained. Numerical solutions to the equation show that, different from the prediction from the linear theory of piezoelectricity, short interface waves become dispersive when electric field gradient is considered.

Keywords: Piezoelectricity, wave, dispersion

DOI: 10.3233/JAE-2009-1006

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 29, no. 2, pp. 101-108, 2009

Authors: Hamid, A.K. | Cooray, F.R.

Article Type: Research Article

Abstract: An algebraic solution is presented to the problem of radiation from an axisymmetric slot on a conducting prolate spheroid confocally coated with an isorefractive material, when the slot is excited by a delta gap source. The formulation of the problem is realized by expanding the electromagnetic field in each region in terms of spheroidal vector wave functions and a set of unknown expansion coefficients. Imposing the boundary conditions at the interface between the surface of the …spheroid and the isorefractive coating, as well as that between the coating and the medium exterior to the coating leads to a set of simultaneous equations, the solution of which yields the unknown expansion coefficients. Numerical results are presented as normalized power patterns and radiation patterns for isorefractive materials, to show the effects of the coating on the radiation from the antenna. Show more

Keywords: Isorefractive, radiation, slotted antenna, spheroid

DOI: 10.3233/JAE-2009-1004

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 29, no. 2, pp. 109-116, 2009

Authors: Kumar, G.V. Nagesh | Amarnath, J. | Singh, B.P. | Srivastava, K.D.

Article Type: Research Article

Abstract: Metallic particle contamination is one of the areas of insulation design that are considered critical. The management and control of particle contamination are crucial considerations as the industry moves forward to higher voltage GIS and long GITL designs using SF_{6} in some components. Free conducting particles may lower the corona onset and breakdown voltage of a GIS/GITL system considerably. Under an applied electric field a conducting particle acquires a charge and lifts off from …its resting position on the conductor when the electromagnetic force from the field becomes equal to the gravity force. Metallic particles move randomly in a horizontally mounted GIS/GITL system due to the electrode surface roughness and particle irregularities. Under 50 Hz AC voltage, the particle can cross the gap at a sufficiently high voltage level. Monte Carlo simulation is carried out on a single phase GIS for determining the motion of free conducting particles in the presence of Electromagnetic field. The results have been presented and analyzed. Show more

Keywords: Metallic particles, electromagnetic field, gas insulated substations

DOI: 10.3233/JAE-2009-1008

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 29, no. 2, pp. 117-129, 2009