International Journal of Applied Electromagnetics and Mechanics - Volume 41, issue 2

Authors: Haque, M.M. | Alam, M.M. | Ferdows, M. | Al-Mdallal, Qasem M.

Article Type: Research Article

Abstract: A numerical study of Soret and Dufour effects on MHD free convective heat and mass transfer unsteady high speed flow of viscous fluid through a porous medium with induced magnetic field is investigated in a rotating system. In this observation, heat and mass fluxes from the medium are considered to be constant for cooling problem with lighter and heavier particles. Numerical values of velocity, induced magnetic field, temperature and concentration are computed by the conditionally stable …explicit finite difference method with stability and convergence analysis. The shear stress, current density, Nusselt number and Sherwood number are also calculated here. Effects of associated parameters on the above mentioned quantities are shown graphically and physical aspects of the problem are discussed in detail. Finally, both the qualitative and quantitative comparisons of present results with previous work are presented in tabular form. Show more

Keywords: MHD, free convective, thermal-mass diffusion, rotating system, induced magnetic field

DOI: 10.3233/JAE-2012-1598

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 41, no. 2, pp. 121-141, 2013

Authors: Rogers, Uri | Clark, David | Jackson, Scott | Ferguson, Tammy | Harris, David

Article Type: Research Article

Abstract: A renewed focus on Free Piston Stirling Engines (FPSE) for Green Solar based power generation provides a vehicle to explore linear alternator technologies for improved performance and efficiency. This paper evaluates Axially Opposed Magnetization (AOM) linear alternators and the potential advantages this technology provides mechanically and magnetically relative to alternator efficiency, while also addressing potential disadvantages from a thermal perspective. Evaluations include numerical analysis, simulation, physical testing, and commercial technology comparisons.

Keywords: Linear alternator, Free Piston Stirling Engine, FPSE, Axially Opposed Magnetization, AOM

DOI: 10.3233/JAE-2012-1599

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 41, no. 2, pp. 143-152, 2013

Authors: Dao, Vanluu | Zhao, Shengdun | Lin, Wenjie

Article Type: Research Article

Abstract: A two-dimensional model coupling of the electromagnetic field, the temperature field and the flow field of preparation of A356 aluminum alloy semi-solid slurry by electromagnetic stirring (EMS) was established. The Power Law Cut-Off (PLCO) model was used to model the semi-solid slurry. The effect of process parameters such as stirring frequency, stirring current, pouring temperature and crucible preheated temperature on the electromagnetic field, temperature field and flow field were investigated by finite element code ANSYS …combined with secondary development INTEL FORTRAN software and corresponding experimental verification. The results show that the electromagnetic field and flow field increase as stirring frequency and stirring current increase. Similarly, temperature field and flow field increase as pouring temperature and crucible preheated temperature increase. However, too high stirring frequency, stirring current, pouring temperature and crucible temperature may lead to rapid increase in the flow field, as a result, strongly turbulent flow might occur. The reasonable process parameters for preparation of A356 alloy semi-solid slurry by EMS were obtained. The simulation results are significantly approved with corresponding experimental ones, that verifying the reliability of the calculation models and the software algorithm. Show more

Keywords: Semi-solid, electromagnetic stirring, slurry preparation, A356 aluminum alloy, PLCO model, process parameter

DOI: 10.3233/JAE-2012-1600

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 41, no. 2, pp. 153-165, 2013

Authors: Singh, R.K.

Article Type: Research Article

Abstract: In the present paper, a disc-loaded circular waveguide structure has been field analyzed for the power loss and attenuation characteristics. The structure has also been simulated with commercially available simulation tool 'CST Microwave Studio'. The analytical results have been found in close agreement with the simulation results. Attenuation characteristics have been observed for a disc-loaded circular waveguide interaction structure made of materials of different electrical conductivity and has been observed that the …material with higher conductivity results in lower attenuation. Further, the variation of attenuation characteristics has been observed for two different azimuthally symmetric modes typically TE_{01} and TE_{02} . Power loss at different surfaces of the disc-loaded circular waveguide excited in TE_{01} mode has also been observed and it has been found that the tip of the discs is the surface where maximum power loss per unit area occurs. Further, it has been found that with increasing the disc-hole radius the ohmic power loss as well as attenuation constant decreases and with increasing the structure periodicity, the ohmic power loss and attenuation increases. Hence, the structure dimensions should be optimally selected for higher bandwidths and gains. Show more

Keywords: Attenuation, disc-loaded circular waveguide, field constant, periodic loading, power loss, power transmitted

DOI: 10.3233/JAE-2012-1601

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 41, no. 2, pp. 167-179, 2013

Authors: Huang, Chung-Hsin | Li, Ching-Lieh | Tuen, Lung-Fai

Article Type: Research Article

Abstract: In this paper, we apply the DDE algorithm to solve the inverse scattering problem for which a two-dimensional (2-D) dielectric cylinder with unknown cross section is buried in a dielectric slab medium. Finite difference time domain method (FDTD) is used to solve the scattering electromagnetic wave of a dielectric cylinder. The inverse problem is resolved by an optimization approach and the global searching scheme dynamic differential evolution (DDE) is then employed to search the parameter space. …By properly processing the scattered field, some EM properties can be reconstructed. One is the location of the dielectric cylinder; the others are the shape of the dielectric cylinder and permittivity of the dielectric cylinder. This method is tested by several numerical examples, and it is found that the performance of the DDE is robust for reconstructing the dielectric cylinder. Numerical simulations show that even when the measured scattered fields are contaminated with Gaussian noise, the quality of the reconstructed results obtained by the DDE algorithm is very good. Show more

Keywords: Inverse scattering, time domain, subgridding FDTD, dynamic differential evolution, slab medium, cubic-spline.

DOI: 10.3233/JAE-2012-1602

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 41, no. 2, pp. 181-192, 2013

Authors: Ullah, M. Habib | Islam, M.T. | Mandeep, J.S.

Article Type: Research Article

Abstract: A parametric study on three different high dielectric substrate materials for antenna miniaturization is conducted in this paper. The antenna substrates of three different dielectric materials in 2 GHz frequency ranges from 7.5 GHz to 9.5 GHz are investigated. Rectangular microstrip antenna on Aluminium oxide, Rogers RT Duroid 6010 and Silicon substrate is designed at the three resonant frequencies of 8.95 GHz, 8.79 GHz and 8.15 GHz respectively. The antenna is designed and analyzed by using …three dimensional full-wave electromagnetic field simulators. The performances of the proposed antenna are analyzed using finite element method formulation within the volumetric region. The overall result shows that, aluminium oxide material substrate performs better in terms of bandwidth, gain and radiation characteristics compare to other two substrate materials. Show more

Keywords: High dielectric material, aluminium oxide, Rogers RT Duroid 6010, silicon, finite element method and microstrip patch antenna

DOI: 10.3233/JAE-2012-1603

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 41, no. 2, pp. 193-198, 2013

Authors: Lai, Ying-Xin | Yang, Lei | Zhang, Shi-Chang

Article Type: Research Article

Abstract: By making use of coupled-wave theory, the transmission characteristics of a defected coaxial Bragg structure which operates in the vicinity of 100 GHz are investigated. Results reveal that the overmoded operation of the example structure excites serious interaction among the operating mode and its neighboring modes, which spoils the passband structure and causes hybrid-mode transmission. However, single-mode output can be ensured by applying Hamming-window-function distribution to the ripple amplitude of the example …structure, and one or more desired narrow passbands can be generated and controlled by adjusting the localized ripple defect or/and the initial phase difference between the outer-wall and the inner-rod ripples. These peculiarities provide potential applications of defected coaxial Bragg waveguides in constructing high-Q open resonators and narrow passband filters in the sub-terahertz and terahertz frequency ranges. Show more

Keywords: Coaxial Bragg structure, localized defect, transmission, passband, mode interaction

DOI: 10.3233/JAE-121604

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 41, no. 2, pp. 199-206, 2013

Authors: Patel, Shobhit K. | Kosta, Y.P.

Article Type: Research Article

Abstract: Magnetic properties were imparted to a naturally nonmagnetic material by metallic inclusions. In this paper, microstrip based meandered radiating structure using artificial substrate has been reported. Here metallic split ring resonators are added in the conventional dielectric substrate to make artificial substrate material. The patch size is reduced 50% using the artificial material. Comparison of artificial substrate material design and conventional material design is shown in this paper. Artificial substrate Design has one …band at 0.64 GHz centre frequency. Design results are obtained by a HFSS (High Frequency Structure Simulator) which is used for simulating microwave passive components. Show more

Keywords: Artificial substrate, Double Negative (DNG), metamaterial, microstrip, Single Negative (SNG), Split Ring Resonator (SRR)

DOI: 10.3233/JAE-121605

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 41, no. 2, pp. 207-216, 2013