International Journal of Applied Electromagnetics and Mechanics - Volume 40, issue 1

Authors: Ghaffar, Abdul | Ahmed, Shakeel | Naqvi, Q.A.

Article Type: Research Article

Abstract: A theoretical investigation is made for the problem of electromagnetic field focussing by wide angle spherical reflector receiving obliquely incident plane waves of linearly polarized monochromatic radiation. The Maslov's method has been applied to determine the electromagnetic fields in the caustic region of the reflector. High frequency field expression which contains caustic region is converted into caustic free field expression by transforming the situation into hybrid domain. The high-frequency field solution that …contains the caustic region is obtained from geometrical optics. The defect in high frequency solution due to geometrical optics is overcome by Maslov's method. Two cases of polarization of the incident wave have been considered, namely, (1) with the field parallel and (2) perpendicular to the meridional plane of incidence. The numerical computations are made to study the behavior of field intensity in caustic region using Maslov's method. The analytical and numerical results obtained from Maslov's method are also compared with method of angular spectrum which are in agreement. Show more

Keywords: High frequency, Maslov's method, geometrical optics, Hamilton, caustic

DOI: 10.3233/JAE-2012-1420

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 40, no. 1, pp. 1-17, 2012

Authors: Pereira de Siqueira Campos, Antonio Luiz

Article Type: Research Article

Abstract: This paper describes the use of anisotropic substrates to improve Frequency Selective Surfaces (FSS) response. Initially, we present the entire formulation to analysis of FSS on anisotropic dielectric substrates. After this, we present numerical and experimental results to point out that the use of anisotropic substrates can improve the FSS response. Those results are compared with isotropic substrates for the same structures. Finally, conclusions are listened.

Keywords: Frequency selective surfaces (FSS), anisotropic substrates, PBN, sapphire

DOI: 10.3233/JAE-2012-1421

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 40, no. 1, pp. 19-25, 2012

Authors: Hassan, Muhammad Haseeb | Mughal, Muhammad Junaid | Ali, Muhammad Mahmood | Naqvi, Qaiser Abbas

Article Type: Research Article

Abstract: The present study deals with the propagation of electromagnetic fields and power in a circular waveguide, with DB-boundary conditions, internally coated with chiral-nihility medium. The two layer circular waveguide defined by DB-boundary conditions, with one layer containing free space while other layer containing chiral-nihility medium, is investigated. DB-boundary conditions require vanishing of normal field components of the D and B vectors, hence termed as DB-boundary conditions. It has been studied that there is non-zero electric and …magnetic fields in free space as well as in chiral-nihility medium in a circular waveguide defined by DB-boundary conditions. Hence, there is non-zero power transfer both in nihility as well as non-nihility regions Show more

Keywords: DB boundary conditions, chiral-nihility medium, circular waveguide

DOI: 10.3233/JAE-2012-1426

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 40, no. 1, pp. 27-35, 2012

Authors: Yang, Wenming | Li, Decai | He, Xinzhi | Li, Qiang

Article Type: Research Article

Abstract: The magnetic levitation force exerted on the magnets immersed in ferrofluid is the theoretical basis of various application of ferrofluid. In this paper, based on the equivalent magnetic charge models and the equivalent current models of cylindrical magnets, magnetic charge image method and current image method are used to calculate the magnetic levitation force exerted on the cylindrical magnets immersed in ferrofluid respectively. The magnetic levitation force under the same conditions is calculated by the Comsol …Multiphysics software according to the mechanical formula after the distribution of the magnetic field is obtained using finite element method. The magnetic levitation force is also measured experimentally, whose results are compared with the theoretical results obtained by the three methods. The analysis shows that the variation law of the magnetic levitation force and the influence by various parameters can be evaluated by the calculation with magnetic charge image method and current image method, but there is great difference between the theoretical results and the experimental results, and the greatest difference are 46% and 62% respectively. The agreement between the theoretical and the experimental results is quite good when the finite element method is used, whose greatest difference is 9%. Show more

Keywords: Ferrofluid, magnets, magnetic levitation force, image method, finite element method

DOI: 10.3233/JAE-2012-1428

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 40, no. 1, pp. 37-49, 2012

Authors: Woo, Dong-Kyun | Lim, Dong-Kuk | Jung, Hyun-Kyo

Article Type: Research Article

Abstract: This paper proposes a rotor-design strategy of interior permanent magnet synchronous machine (IPMSM) considering various design constraints for a fuel-cell electric vehicle. The conventional process in the rotor design only considers the magnitude of the iron loss or the magnet loss while neglecting the loss distributions in the rotor core. This approach results in a design where losses are accumulated on a localized region in the rotor core, especially in the case of IPMSM with a …fractional number of slots per pole. This can cause significant irreversible demagnetization of the permanent magnets since the rotor core usually suffers from poor heat transfer. The proposed strategy targets this problem by focusing on the loss distributions according to driving condition. In addition, it offers a parallel approach where mechanical stress analysis is combined with the rotor design process in order to guarantee mechanical strength by centrifugal force at maximum speed. The validity of proposed method was verified by comparing simulation result using the finite element method with experimental data. Show more

Keywords: Demagnetization, fuel cell electric vehicle (FCEV), interior permanent magnet synchronous motor (IPMSM), rotor

DOI: 10.3233/JAE-2012-1429

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 40, no. 1, pp. 51-66, 2012

Authors: Zhu, Xiaohua | Lai, Chunlin

Article Type: Research Article

Abstract: To mitigate the severe drillstring vibration during oil and gas drilling, this paper presents a design of mixed mode magnetorheological (MR) fluid damper based on the electromagnetic finite element analysis and Bingham plastic model. The 2D axisymmetric finite element model has been established, and a structural optimization method on the base of magnetic circuit design has also been put forward. The effects of structural parameters such as the radius of bobbin, the thickness of cylinder and …the active bobbin length on the flux density inside the fluid gap have been analyzed, which consequently obtain the appropriate design with a higher and more even magnetic intensity. Besides, this analysis has found the relations between damping force, amplifying factor and vibration velocity under different field currents by a typical Bingham plastic model and test data when considering the negative effects of temperature on MR fluid, finally, made prediction on the performance of the MR fluid damper. The main research of the paper lays an important foundation to develop control strategy of the MR fluid damper for drillstring. Show more

Keywords: Drillstring vibration, magnetorheological fluid damper, magnetic circuits, finite element analysis, optimal design, temperature

DOI: 10.3233/JAE-2012-1430

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 40, no. 1, pp. 67-83, 2012