International Journal of Applied Electromagnetics and Mechanics - Volume 42, issue 4

Authors: Lu, Rongsheng | Yi, Hong | Wu, Weiping | Jiang, Yun | Ni, Zhonghua

Article Type: Research Article

Abstract: We propose a general global optimal algorithm to optimize the miniature permanent magnet structure of a micro magnetic resonance chip (μ NMR-chip). For this purpose, we analyze the sensitivity of the permanent magnet structure to the design variables and determine the optimization variables. After this, radial basis function neural networks (RBFNNs) are constructed to model the objective functions, and the nondominated sorting genetic algorithm II (NSGA II) is improved by introducing a different …weighting factor for each objective function in calculating the crowding distance. Combining the RBFNN with the improved NSGA II optimizes the miniature permanent magnet structure. Through comparison, the optimization solutions are proven effective. Finally, the optimized permanent magnet structure is manufactured and tested experimentally. After optimization, the volume of the permanent magnet block is reduced by 39%, and the permanent magnet becomes easier to manufacture. Show more

Keywords: Microfluidic chip, nuclear magnetic resonance, permanent magnet, multiobjective optimization

DOI: 10.3233/JAE-131678

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 4, pp. 479-489, 2013

Authors: Taravati, Sajjad

Article Type: Research Article

Abstract: In this article, design method of 3-dimensional external cloak based on the coordinate transformation theory has been studied. The relative constitutive parameters of the complementary media and the core material of the external cloak are derived. In the proposed external cloak, the cloaked object is not blinded within the cloaking shell because it's located outside of the cloak and can communicate with the outer region while the object is hides from electromagnetic waves incident from different …angles. Full-wave simulations in three dimension domain with both plane and spherical wave irradiations for cloaking homogeneous and inhomogeneous objects have been carried out to verify the efficiency of the proposed 3-D external cloak. Show more

Keywords: Coordinate transformation, electromagnetic cloaking, external cloak, invisibility, three-dimensional

DOI: 10.3233/JAE-131679

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 4, pp. 491-499, 2013

Authors: Li, Y.S. | Liu, L.B. | Meng, W.Q. | Cai, Z.Y.

Article Type: Research Article

Abstract: In this paper, an interfacial penny-shaped crack between magnetoelectroelastic thin film and elastic substrate subjected to mechanical and electric loads is investigated. Four kinds of crack-face magnetoelectrically boundary conditions are adopted. Using Hankel transform technique, the mixed boundary value problem is reduced to a system of singular integral equations. The integral equations are further reduced to a system of algebraic equations with the aid of Jacobi polynomials. The stress intensity factor and …energy release rate are determined. Numerical results reveal the effects of electric and magnetic loadings, magnetoelectroelastic boundary conditions and material parameters of composite on crack propagation and growth. The results seem useful for design of the magnetoelectroelastic composite structures and devices of high performance. Show more

Keywords: Interfacial crack, penny-shaped crack, Hankel transform, energy release rate, magnetoelectroelastic material

DOI: 10.3233/JAE-131680

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 4, pp. 501-517, 2013

Authors: Ghoggal, Adel

Article Type: Research Article

Abstract: This paper proposes a novel analytical model of air-gap eccentricity in induction motors (IMs) by allowing teeth saturation due to the local air-gap over-fluxing to be taken into account. The approach takes into account the magnetic saturation by means of a fictive permeance variation while supposing that, under air-gap eccentricity conditions, the saturation factor must be revaluated in function of the varying air-gap length. The well-known 2D-modified winding function approach (2D-MWFA) is used to get the …formalism of the inductances by assuming a partial uniform rise of the saturation factor with respect to the air-gap length. We show that applying the new approach confirms that the magnetic saturation reduces the asymmetry of the air-gap flux distribution due to rotor eccentricity. In contrast to the harmonic and flux models, the proposed one allows us to proceed with a full dynamic simulation without any need for the experimental data. Thanks to a fast convolution-based technique of inductance calculation, we demonstrate that the 2D-MWFA preserves its major qualities even with these new extensions. The study is supported by simulation and experimental results. Show more

Keywords: Induction motor, 2D-MWFA, convolution, FFT, space harmonics, skew, teeth saturation, air-gap eccentricity

DOI: 10.3233/JAE-131682

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 4, pp. 519-537, 2013

Authors: Shirvani Moghaddam, Shahriar

Article Type: Research Article

Abstract: The main objective of this paper is to model environmental effects on the read range of radio frequency identification (RFID) system. In order to evaluate the performance of an RFID system in real applications, electric and magnetic radiated fields (E or H) of a circular loop antenna should be derived. In this investigation, three cases are considered, free space model, the case that there is a perfect parallel or non-parallel surface, and finally the general model …considering non-parallel non-perfect conductive/dielectric surface. In general model, besides the method of images, a new approach is proposed which model non-parallel main and image CLAs as two equivalent vertical and horizontal loops. According to this model, the radiated fields and also induced voltage are functions of the current intensity, wavenumber, reflection coefficient of the surface, both angle and the distance between antenna and surface, and the distance between the RFID tag and reader. To compare the analytical values extracted from E and B formulas of proposed model and associated results derived from computational methods, MATLAB and FEKO outputs are compared in the same conditions. Using this new proposed model, the performance of an RFID system operating in metal environment and also effective read range can be evaluated. It is also able to show the environmental effects on radiated fields of reader as well as tag's antenna. In addition, the interference effect of different RFIDs can be easily modeled by these new formulas. Show more

Keywords: RFID, tag, reader, circular loop antenna, environmental effects, radiated fields

DOI: 10.3233/JAE-131683

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 4, pp. 539-559, 2013

Authors: Gulistan, Samina | Syed, A.A.

Article Type: Research Article

Abstract: In electromagnetics, a set of boundary conditions requiring vanishing of the normal components of the flux densities D and B (DB boundary) or their normal derivatives (D'B' boundary) have assumed great importance, recently. In the present study, we employ D'B', DB' and D'B boundary conditions to investigate the fields in a three layered fractional dual planar waveguide. Middle layer of the waveguide is filled with air and other two layers are filled with chiral nihility metamaterial. …Fractional dual solutions for the waveguide are obtained using a fractional curl operator with a parameter 'α' defining the fractional order of the operator. For limiting values of the parameter, i.e., α =0 and α =1, the solutions to the Maxwell's equations correspond to the original and dual to the original solutions, respectively. Whereas, in general ( 0<α<1), so called intermediate solutions are obtained. It has been noted that fields do exist in chiral nihility material backed by D'B', DB' or D'B boundary, and a circular wave behaviour of the fields is observed in the core of the waveguide. In this sense DB', D'B and D'B' chiral nihility waveguides behave identical to their DB counterpart. Show more

Keywords: Flux densities, fractional curl operator, chiral materials, waveguides

DOI: 10.3233/JAE-131684

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 4, pp. 561-578, 2013

Authors: Guo, Hui | Wang, Yansong | Wen, Quan

Article Type: Research Article

Abstract: Metal Injection Molding (MIM) technology is introduced into the EFI production processing. Magnetic circuit of the EFI is designed, and three different kinds of EFI samples are manufactured. Through comparisons of simulation and experiments, the comprehensive performance of one EFI sample, which is made of Fe-based nanocrystalline soft magnetic alloy by MIM technology, is found to be obviously better than that of others, which are made of traditional material and processing. The dynamic response times of …opening and closing are respectively shorter by 32.5% and 62.2%, and the dynamic flow range is wider by 8.3%. Show more

Keywords: Electronic gasoline injector, MIM technology, electromagnetic performance, dynamic response

DOI: 10.3233/JAE-131685

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 4, pp. 579-588, 2013

Authors: Ghadi, Ariyan Zare | Noroozi, Mohammad Javad | Esfe, Mohammad Hemmat

Article Type: Research Article

Abstract: In this research, effects of adding nano-sized particles to base fluid on heat transfer and fluid flow in a lid-driven cavity in presence of magnetic field has been numerically analyzed. In the present work, nano-sized additives are alumina nanoparticles which play controlling role in the adjustment of heat transfer performance and fluid motion behavior for an application which is under a variable strength magnetic field. Since a fairly low value of volume fraction is assumed in …this research, nanoparticles together with the base fluid behave like a new fluid. Top moving lid and bottom walls of cavity are insulated, whereas left and right walls are defined as hot and cold sources, respectively. Relevant parameters in the present article are Reynolds number, considered to be 100, Prandtl number, assumed to be 6.2, Rayleigh number (10^{2} < Gr < 10^{5} ), volume fraction number (0 < φ 0.05) and Hartmann number (0 < Ha < 50). Results are presented in form of streamlines, isotherms, local and average Nusselt numbers. Show more

Keywords: MHD flow, nanofluid, cavity, finite volume method, free convection

DOI: 10.3233/JAE-131686

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 4, pp. 589-602, 2013

Authors: Li, Xi | Yang, Lin | Wang, Min

Article Type: Research Article

Abstract: A novel design of wideband metallic contact annular stacked patch antenna is presented for global navigation satellite system (GNSS) in this letter. The wideband characteristic is achieved by employing L-probe coupled feeding structure. The antenna is fed by four-output-ports feeding network composed of three normal Wilkinson power dividers. As a result, the antenna has an effective bandwidth of 54.8% from 1.1 to 1.93 GHz for VSWR < 2, and 42.9% from 1.1 to 1.7 GHz …for AR < 3 dB respectively, which is sufficiently enough to operate for the satellite navigation frequencies including GPS, GLONASS, Galileo and Compass (1100 MHz–1600 MHz). Metallic contact annular stacked patch is introduced in this design to obtain stable gain bandwidth, broad beam width and good axial ratio at low elevation. The final antenna provides very good circularly polarized radiation for GNSS. Show more

Keywords: GNSS, wide band, metallic contact annular stacked patch antenna

DOI: 10.3233/JAE-131687

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 4, pp. 603-611, 2013

Authors: Ghaffar, A. | Shahbaz Ahmad, H. | Naqvi, Q.A.

Article Type: Research Article

Abstract: A theoretical investigation has been carried out to analyze the transmission of electromagnetic field through a slab of quadric inhomogeneous chiral medium. The transmission coefficients at dielectric-chiral and chiral-dielectric interfaces are derived analytically. The transmitted electromagnetic field expressions have been obtained using Maslov's method. The derived analytical field expressions at caustic or focal point of quadratic inhomogeneous chiral slab have been solved numerically using MATHEMATICA. The result obtained using Maslov's method are …compared with Hyugen Kirchhoff's integral which are in good agreement. Show more

Keywords: High frequency, Maslov's method, chiral, quadratic, caustic

DOI: 10.3233/JAE-131688

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 4, pp. 613-622, 2013