International Journal of Applied Electromagnetics and Mechanics - Volume 34, issue 3

Authors: Yahaghia, Alireza | Hafner, Christian | Fallahi, Arya | Smajic, Jasmin | Cranganu-Cretu, Bogdan | Vahldieck, Ruediger

Article Type: Research Article

Abstract: Different optimization algorithms are applied to determine the best configuration of a shielding device for eddy currents. The algorithms include seven stochastic binary optimizers, which are based on the concept of genetic algorithms and evolutionary strategies, as well as one quasi-deterministic optimizer based on an algorithm inspired by hill-climbing strategies. The comparison of results obtained from each algorithm shows a very high probability of finding global optima when a special quasi-deterministic algorithm …is applied. Show more

Keywords: Stochastic optimization, eddy currents, electromagnetic shielding

DOI: 10.3233/JAE-2010-1307

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 34, no. 3, pp. 141-154, 2010

Authors: Xu, Lizhong | Geng, Yanbo

Article Type: Research Article

Abstract: In this paper, using the differential equation of the armature motion for the electromagnetic Railguns, influences of the driving current distribution on the velocities of the projectile are investigated. Several kinds of the typical energy losses are considered. The influences of the driving current distribution on the transfer efficiency of the railgun system are analyzed. For a given exit velocity of the projectile and rail length, a proper relative time ratio of the pulse currents is …determined which corresponds to the optimum system transfer efficiency. The results can be used to design pulse current distribution of the railgun system. Show more

Keywords: Railgun, velocities of the projectile, transfer efficiency, pulse currents, relative time ratio

DOI: 10.3233/JAE-2010-1308

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 34, no. 3, pp. 155-170, 2010

Authors: Liu, Bo | Jiang, Qing | Yang, Jiashi

Article Type: Research Article

Abstract: We study thickness-shear vibration of a piezoelectric crystal plate whose one surface is in contact with a viscous fluid layer of finite thickness. The crystal plate is driven by a lateral electric field. The theory of piezoelectricity and the theory of Newtonian fluids are used. Both free and forced vibration solutions are obtained. An approximate expression for the frequency shift in the crystal plate due to the presence of the fluid is presented. The admittance of …the structure is also calculated. The results are useful for acoustic wave fluid sensors. Show more

DOI: 10.3233/JAE-2010-1309

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 34, no. 3, pp. 171-180, 2010

Authors: Imran, Amjad | Naqvi, Q.A. | Hongo, K.

Article Type: Research Article

Abstract: In this paper, diffracting behavior of a perfectly electromagnetic conductor (PEMC) strip has been studied. Both the E- and H-polarization are considered. The method of analysis is Kobayashi Potential (KP). Imposition of boundary conditions results into dual integral equations (DIEs). These DIEs are solved by using the discontinuous properties of Weber-Schafheitlin's integral. The resulting expressions, finally, reduce to matrix equations with infinite number of unknowns whose elements are expressed in terms of infinite integrals. …These integrals are hard to solve analytically so numerical simulation is done. Illustrative computations are presented for different parameters of interest especially the dependence of co-polarized and cross-polarized components on the admittance parameter. Show more

DOI: 10.3233/JAE-2010-1310

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 34, no. 3, pp. 181-193, 2010

Authors: Son, Hungsun | Bai, Kun | Lim, Jungyoul | Lee, Kok-Meng

Article Type: Research Article

Abstract: Design and control of many electromagnetic actuators involve solving three dimensional (3D) magnetic fields of permanent magnets and/or electromagnets in the presence of magnetic conducting surfaces. This paper extends the distributed multipole (DMP) method, which offers compact but precise analysis for three dimensional magnetic fields in closed form, to account for the effects of magnetic conducting boundaries using the image method on the torque generated by electromagnetic actuators. We validate the proposed …method referred to here as DMP-Image method by comparing the calculated torques against results computed by a finite element method (FEM). While two methods agree to within 5% in maximum torque, the DMP-image method takes less than 1% of the FEM computation time. Finally, we demonstrate the DMP-Image method to design a spherical motor in a class of multi-DOF actuators. While developed in the context of the multi-DOF actuators, the modeling methods presented in this paper are applicable to design of other PM-based actuators. Show more

Keywords: Magnetic field, dipole, magnetic conducting boundary, image method, spherical motor

DOI: 10.3233/JAE-2010-1311

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 34, no. 3, pp. 195-210, 2010