International Journal of Applied Electromagnetics and Mechanics - Volume 47, issue 1

Authors: Kim, Tae Heoung

Article Type: Research Article

Abstract: A 3-phase flux-reversal motor (FRM) driven by a 6-switch converter has been studied for its various merits such as a low inertia, a high efficiency and fault tolerance. However, it is needed to develop the FRM with a 4-switch converter to reduce motor and converter construction costs. Among the many different 4-switch converter topologies, the one with a compensated current regulation base on a novel pulse width modulation (PWM) control technique has been proposed as a …good solution. In this paper, we introduce a two dimensional time-stepped voltage source finite-element method (2D-FEM) to analyze the FRM driven by the proposed 4-switch converter. We also compare the characteristics of the FRM when the compensated current regulation is adopted or not. To verify the analysis method and simulated results, the 4-switch converter and the prototype FRM are built and experiments are performed. Show more

Keywords: Flux-reversal machine, 4-switch converter, finite element method

DOI: 10.3233/JAE-130065

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 1-9, 2015

Authors: Sharma, Ashish Kumar | Gupta, Navneet

Article Type: Research Article

Abstract: An improved design of microelectromechanical system (MEMS) switch for radio frequency (RF) applications has been proposed using non-uniform serpentine flexure structure. An analytical modeling of non-uniform serpentine flexure is obtained using small displacement theory and is compared with finite element method (FEM). It is observed that in comparison to the uniform serpentine flexure reported so far, the proposed design shows a considerable reduced spring constant of 0.65 to 0.04 N/m and pull-in voltage of 15 to …3 V with better RF power handling capabilities of 4.29 to 0.2 W for span beam length varying from 100 to 280 μm. The proposed switch design shows with better RF response in terms of return loss of −20 dB and isolation of −40 dB at 26 GHz. Show more

Keywords: MEMS switch, FEM, radio frequency, spring constant

DOI: 10.3233/JAE-130085

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 11-19, 2015

Authors: Mahmoodi, Mostafa | Esfe, Mohammad Hemmat | Akbari, Mohammad | Karimipour, Arash | Afrand, Masoud

Article Type: Research Article

Abstract: Magnetohydrodynamic natural convection fluid flow and heat transfer in a square enclosure with a pair of source and sink on its walls, filled with liquid Gallium fluid with Prandtl number of 0.02 has been investigated numerically. The heat source and heat sink are maintained at a constant temperature T_{h} and T_{c} , respectively with T_{h} > T_{c} . By variation of relative location of the heat source and sink on the walls …of the enclosure, five different cases are generated. The governing equations written in terms of the primitive variables are solved numerically using the finite volume method and the SIMPLER algorithm. Using the developed code, a parametric study is performed, and the effects of the Rayleigh number, the Hartman number, and the locations of the source and sink on the fluid flow and heat transfer inside the enclosure are investigated. The results show that the flow and temperature distributions inside the enclosure are affected by the strength of the magnetic field, the Rayleigh number, and the relative location of the heat source and sink. The magnetic field decreases the rate of heat transfer, suppresses the convection heat transfer, and tends to slows down the flow velocity in the cavity. Moreover in some cases the magnetic field changes the flow pattern inside the enclosure. Show more

Keywords: Magnetic field, natural convection, square enclosure, heat source, heat sink

DOI: 10.3233/JAE-130097

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 21-32, 2015

Authors: Tang, Mingsheng | Zou, Huiming | Xu, Hongbo | Shao, Shangquan | Tian, Changqing

Article Type: Research Article

Abstract: The electromagnetic transduction coefficient has a strong influence on efficiency as well as the sensorless control of linear oscillation electrical machine (LOEM). This paper presents a reciprocal LOEM method for measurement of the electromagnetic transduction coefficient, to investigate the effect of the magnet length on the characteristics of the transduction coefficient. The result shows that the transduction coefficient has two regimes, a constant regime and a nonlinear regime. As the harmonic distortion …begins to appear in the induced electromotive force, the electromagnetic transduction coefficient passes from the constant regime to the nonlinear regime, and the corresponding stroke is defined as critical stroke. The range of constant regime equals the observed critical stroke, and the critical stroke is 8.81 mm and 10.78 mm when the length of the permanent magnet is 11 mm and 13 mm respectively. The relationship among the geometrical dimension of yoke and permanent magnet, the critical stroke and the stroke of the LOEM are carefully investigated. Then optimal lengths for both the yoke and the permanent magnet are suggested for the LOEM design with the rated stroke, to achieve the highest efficiency and least material cost simultaneously. Show more

Keywords: Electromagnetic transduction coefficient, magnet length, nonlinear characteristic, harmonic distortion

DOI: 10.3233/JAE-130110

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 33-43, 2015

Authors: Muthu, Ganesh Madhan | Kumar, Jagadeesh Velan | Jayaraman, Roopchand

Article Type: Research Article

Abstract: Radar Cross Section (RCS) computation and analysis are carried out for a high speed, kinetic energy missile at 35 GHz. The radar cross section simulations were performed under bistatic conditions, using a 3D Electromagnetic field solver. RCS values for standard geometries such as cylinder, cone – cylinder combination are calculated under different excitation conditions and the results are verified with literature, so as to fix the settings in the solver. A maximum RCS value for the …missile is obtained as −4.9 dBsm under broad side excitation. RCS values of −22.25 dBsm and 4.94 dBsm are obtained for 0° (Nose cone) and 180° direction, when excited in the frontal region, i.e., 0° azimuth and 0° elevation. Further, monostatic simulation under 0° to 180° excitation shows a large RCS value of −4 dBsm at 90°, corresponding to large surface area of the missile. The effect of frequency on the RCS of the missile is also determined in 30 to 40 GHz band. A comparison of integral equation solver and asymptotic solver for RCS computation indicates almost similar values, with a deviation less than 5 dB in most of the ranges. However, with compromise on accuracy, the asymptotic solver is found to consume only 5% of the total time required by integral equation solver. Show more

Keywords: Radar cross section, electromagnetic field solver, kinetic energy missile, Ka band, active protection system

DOI: 10.3233/JAE-130139

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 45-59, 2015

Authors: Xu, Ming-Xiu | Chen, Zhang-Hua | Xu, Min-Qiang | You, Tian-Qing

Article Type: Research Article

Abstract: In metal magnetic memory (MMM) detection, the Jiles-Atherton model describes material magnetization caused by the geomagnetic field and cyclic stress. However, characterization of the effects of fatigue damage on magnetization remains an issue. In this paper, an expression for magnetization intensity M_{0} related to dislocation and plastic strain amplitude ε_{p} was incorporated into a modified Jiles-Atherton model. To validate the M_{0} expression, …standard tensile fatigue tests were performed. Results indicate that the domain wall pinning parameter k_{1} in M_{0} is linear in both dislocation density ρ and average dislocations slippage distance �λ, as is also the shear plastic strain amplitude in the stress control fatigue. The stress amplitude in strain control fatigue however is linear with respect to ρ^{1/2} . Therefore, M_{0} can be expressed as a function of stress and ε_{p} (or �λ and stress amplitude). Experiments showed that calculated M_{0} variations in fatigue development processes can reflect a variation law in the MMM signal, with certain differences. There is a numerical difference between H_{px} and M_{0} because the surface magnetic field is much weaker than that within the ferromagnetic material. H_{px} increases after macro crack initiation caused by an additional material demagnetization field and a leakage field near the crack during cracking. Show more

Keywords: Fatigue, metal magnetic memory, Jiles-Atherton model, dislocations

DOI: 10.3233/JAE-130159

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 61-73, 2015

Authors: Jin, Longwen | Lei, Bin | Li, Zhiyuan | Zhang, Qian

Article Type: Research Article

Abstract: An analytical model is proposed to investigate the dynamic behavior of rail under the effect of both the rail repulsive force and the armature contact force. The rail is modeled as a Bernoulli – Euler beam resting on a continuous elastic foundation with simply support at both ends of the rail. Numerical simulations are carried out using the analytical model at below, near and above the critical velocities respectively. The results show that the dynamic response …of the rail under the effect of both the repulsive force and contact force is more intensive and complicated than the case in which only the repulsive force acted. The additional oscillations caused by the contact force may increase the possibility of electrical contact failure between the armature and the rails. For more detailed analysis, the analytical model is needed to take into account the varying elastic stiffness and damping effect of practical railgun structure. Show more

Keywords: Dynamic response, critical velocity, armature movement, railgun

DOI: 10.3233/JAE-130168

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 75-82, 2015

Authors: Fiaz, M.A. | Ashraf, M.A.

Article Type: Research Article

Abstract: An analytic technique based on spectral plane wave representation of fields (SPRF) for the scattering of a plane wave from a perfectly electric conductor (PEC) cylinder coated with double positive (DPS) or double negative (DNG) materials buried beneath a slightly rough surface is formulated. Small Perturbation Method is used to consider scattering from rough surface. Spectral integrals are evaluated using saddle point method. A comparison with the previously available results has been done for validity. Both …TM and TE polarizations are considered to obtain results varying different geometrical and physical parameters. Show more

Keywords: Scattering, rough surface, DNG, buried object

DOI: 10.3233/JAE-130171

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 83-93, 2015

Authors: Ezzat, Magdy A. | El-Karamany, Ahmed S. | El-Bary, Alaa A.

Article Type: Research Article

Abstract: Some mathematical models of the equations of generalized magneto-thermo-viscoelasticty for isotropic media are given. The formulation is applied to each generalization of the Lord- Shulman theory, the Green-Lindsay theory and the Chandrasekharaiah and Tzou theory as well as to the coupled theory. The state space approach is adopted for the solution of problems in the absence or presence of heat sources. The Laplace-transform technique is used. A numerical method is employed for the inversion of the …Laplace transforms. Numerical results for the stress distribution are given and illustrated graphically for each problem. Comparisons are made with the results predicted by the four theories. Show more

Keywords: Generalized thermoelasticity, magneto-thermo-viscoelasticity, Lord-Shulman theory, the Green-Lindsay theory, chandrasekharaiah and tzou theory, coupled theory, state space approach

DOI: 10.3233/JAE-130177

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 95-111, 2015

Authors: Silva, Anderson O. | Cardoso, Markos P. | Giraldi, Maria T.M.R. | Costa, João C.W.A.

Article Type: Research Article

Abstract: Surface plasmon-polariton excitations are electromagnetic modes responsible for a huge field confinement at the interface between a conductor and a dielectric. These modes mitigate light scattering even below the diffraction limit, which allows the reduction in size of several kinds of electromagnetic devices such as waveguides, resonators and sensors. Within this framework, we apply the FEM-RBCI formulation to investigate the response at the optical spectrum of a nanocavity filled with silver nanodisks. Computational …simulations show that the coupling between localized surface plasmon modes excited at the periphery of the nanodisks yields a high sensitivity degree in an ultra-compact area. Such sensitivity is nearly constant and covers a wide range of refraction indexes of the surrounding medium. Furthermore, it is not required any external phase matching technique to achieve surface plasmon resonance. These characteristics demonstrates the great potential of the structure to improve optical sensing applications. Show more

Keywords: Localized surface plasmon modes, nano-optical devices, refraction index sensors, FEM-RBCI method

DOI: 10.3233/JAE-130182

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 113-123, 2015