International Journal of Applied Electromagnetics and Mechanics - Volume 38, issue 4

Authors: Jung, Sang-Yong | Lee, Dongsu | Choi, Min-Goo | Kim, Jong-Wook

Article Type: Research Article

Abstract: In this paper, optimal design of the direct-driven PM wind generator, combined with uDEAS (univariate Dynamic Encoding Algorithm for Searches) and FEA (Finite Element Analysis), has been performed to maximize the Annual Energy Production (AEP) over the whole operating wind speed. In particular, an adaptive scheme of arranging search variable sequence in uDEAS is newly proposed according to variable's measured gradient to cost function. The proposed adaptive scheme is embedded in uDEAS and validated through two …test functions, and the modified uDEAS is applied to optimal design of the direct-driven PM wind generator. With the comparable quality of the attained solution, uDEAS enormously reduces computation time when compared with Genetic Algorithm (GA) implemented by the parallel computing method. Show more

Keywords: Permanent magnet generator, optimization methods, wind power generation, univariate dynamic encoding algorithm for searches, gradient information

DOI: 10.3233/JAE-2011-1403

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 38, no. 4, pp. 167-180, 2012

Authors: Farooqi, Abdul Razzaq | Mughal, Muhammad Junaid | Mehmood, Muhammad Qasim

Article Type: Research Article

Abstract: High frequency electromagnetic field expressions are analyzed for the focal region of a circular reflector coated with chiral medium. Maslov's method has been used for the study of focal region fields because geometrical optics is an approximate method and fails at the focal points. The effects of chirality parameter, thickness of chiral coating and permittivity of the medium on the focused fields are observed. It is concluded from the results that focused field strength increases with …increase in chirality parameter, relative permittivity and thickness of the chiral coating. Show more

Keywords: Circular reflector, chiral medium, perfect electric conductor, Maslov's method, geometrical optics

DOI: 10.3233/JAE-2012-1422

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 38, no. 4, pp. 181-193, 2012

Authors: Singh, R.K.

Article Type: Research Article

Abstract: The present paper is devoted to the study of mode competition and control in a 170 GHz gyrotron cavity for potential application in electron cyclotron resonance heating (ECRH) of plasmas. An extensive analysis has been carried out for coupling coefficient, start oscillation current, voltage depression, and limiting current for the candidate modes in the gyrotron cavity resonator. The study reveals that the main competing modes for TE_{28,8}^{-} come from TE_{25,9}^{+} and …TE_{27,8}^{-} . The optimum beam position for TE_{28,8}^{ - } mode is found to be at 8.28 mm. To avoid excitation of competing modes, it has been found that slight increase in electron beam radius from 8.28 mm to 8.40 mm avoids the excitation of all the competing modes. Based on the considerations of coupling coefficient, start oscillation current, voltage depression, and limiting current; the TE_{28,8}^{-} mode is selected as the operating mode. Show more

Keywords: Gyrotron, cavity design, mode competition

DOI: 10.3233/JAE-2012-1423

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 38, no. 4, pp. 195-202, 2012

Authors: Zhao, Pei | Zhang, Xingyi | Liang, Yirui | Zhou, Youhe

Article Type: Research Article

Abstract: In this paper, the influences of compressive stress on the narrow hysteresis (magnetostriction hysteresis, W_h ) and maximum piezomagnetic coefficient (d_{33}^{Max} ) of the <110> oriented Tb_{0.27} Dy_{0.73} Fe_{1.95} polycrystalline alloys have been investigated at high drive levels. The simultaneous measurements of magnetostriction and magnetization are carried out as a function of applied magnetic field 0 < H < 800 kA/m and compressive …stress 0 to 50 MPa. The results show that the magnetostriction increases sharply in the low and/or moderate magnetic field, and than gains its saturation slowly with increase of the applied magnetic field. However, according to increase of the compressive stress, the magnetostriction decreases in the low and moderate magnetic field, while the saturation magnetostriction (λ _s ) increases. Specifically, λ _s increases from 1143 × 10^{ - 6} to 1778 × 10^{ - 6} when the compressive stress increases from 0 to 50 MPa and W_h increases from 7.90 to 27.22 kA/m at the same conditions. In addition, the characteristics of d_{33}^{Max} are reported under varied compressive stresses. It is found that the higher compressive stress the lower is d_{33}^{Max} , while at a fixed compressive stress, d_{33}^{Max} in the forward magnetostriction process is lower than that in the reversal magnetostriction process. These results presented are available for a kind of Tb-Dy-Fe alloys applications. Show more

Keywords: Magnetostrictive material, magnetostriction hysteresis, piezomagnetic coefficient

DOI: 10.3233/JAE-2012-1424

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 38, no. 4, pp. 203-209, 2012

Authors: Zhong, Fuqun | Zhang, Bo | Fan, Yong | Zhao, Minghua | Chen, Zhe

Article Type: Research Article

Abstract: Accompany with the rapid development of millimeter-wave science and technology, sub-harmonically pumped mixers have received more and more attention. One important issue of the mixer is its parasitic parameters of the diode structure play an important role in the conversion loss. Therefore, the influence of parasitic parameter on the performance of the mixer is studied by extraction of parasitic parameter of antiparallel GaAs Schottky diode in this research. Based on the research, a mixer working in …the 91–98 GHz band is designed and fabricated based on rogers substrate process. The single side band (SSB) conversion loss is about 8 ∼ 11 dB when pumped with 6mW of local oscillator power and minimum SSB conversion loss of 8 dB is measured at 93 GHz. The measured performance of the proposed mixer is sufficient and robust for the foreseen applications. Show more

Keywords: Extraction of parasitic parameter, sub-harmonic mixer, fix-tuned, planar Schottky diodes

DOI: 10.3233/JAE-2012-1425

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 38, no. 4, pp. 211-215, 2012

Authors: Li, Zheng | Sun, Huiqin | Wu, Xueli | Liu, Qingrui

Article Type: Research Article

Abstract: Modeling and torque characteristics analysis are important for actuators or motors with complicated structures. Based on the presented configuration design, the magnetic field and torque calculation for a multiple degrees-of-freedom (M-DOF) spherical actuator are performed using 3D FEM. To reduce the computation workload, a simplified torque calculation model and non-linear system dynamic model have been proposed, and magnetic levitation mechanism is developed for alleviating the friction and resistance to improve the dynamic …performance of this M-DOF actuator. A linear mathematical model of the levitation force is deduced and corresponding control scheme with power drive unit is discussed. Then the diagonal recurrent neural network (DRNN) based control scheme is presented to improve the performance of levitation by adjusting parameters online as identifiers. Simulation and experiment results show that the actuator can effectively implement 3-DOF motion combined with levitation mode, and that the proposed approach can be applied to M-DOF actuators of the same kind effectively. Show more

Keywords: Magnetic levitation, M-DOF actuator, modeling, neural network control

DOI: 10.3233/JAE-2012-1427

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 38, no. 4, pp. 217-230, 2012

Article Type: Other

Abstract: Author Index Volume 38 (2012)

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 38, no. 4, pp. 231-233, 2012