International Journal of Applied Electromagnetics and Mechanics - Volume 48, issue 4

Authors: Shiao, Yaojung | Nguyen, Quang-Anh | Zhang, Zhengyang

Article Type: Research Article

Abstract: Conventional MR brake design with single ring-type electromagnetic pole is insufficient in torque increment. A new magnetorheological (MR) brake is designed in this paper to employ magnetic flux effectively on the overall surface of a rotating brake disc. The new MR brake features multiple electromagnetic poles surrounded by several coils to maximize the active chaining areas for the MR fluid, resulting in improvement of brake torque. It also provides flexibility for torque rise by increasing either radial dimension or axial length of the rotating disc. Optimal design parameters are obtained by simulation and the capabilities of the new MR brake …are confirmed. Afterwards, a prototype is manufactured and tested to verify system performance. The tested torque output cohered to the simulation results and the feasibility of the system is proved. The torque analysis shows that the new brake design can offer an advantage in broader ranges of operation compared with conventional MR brake. Show more

Keywords: Magnetorheological fluids, MR brake, multiple electromagnetic poles

DOI: 10.3233/JAE-130183

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 48, no. 4, pp. 309-326, 2015

Authors: Tang, Enling | Zhang, Lijiao | Zhang, Qingming | Wang, Meng | Xiang, Shenghai | Liu, Shuhua | Xia, Jin | He, Liping | Han, Yafei | Shi, Xiaohan | Wangi, Di

Article Type: Research Article

Abstract: In order to understand luminous efficiency of the visible wavelength and the infrared wavelength range generated by hypervelocity impact natural dolomite plate, experimental measurement of the light flash created by hypervelocity impact natural dolomite plate were performed in the visible wavelength range by using the optical transient pyrometer measurement system and two-stage light gas gun loading system at the different impact velocity and the projectile incident angles of 45° and 60° (with the angle along the target plane), respectively. Based on the Planck's blackbody continuous radiation law in the visible wavelength range, luminous efficiency extrapolate to infrared wavelength range by …combining with Matlab computer programming, the calculated results of the luminous efficiency showed that the luminous efficiency of the light flash created by hypervelocity impact natural dolomite plate in the infrared wavelength range was approximately 1∼1.5 times in the visible wavelength range. Show more

Keywords: Hypervelocity impact, impact light flash, optical transient pyrometer, luminous efficiency, visible wavelength, infrared wavelength

DOI: 10.3233/JAE-140058

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 48, no. 4, pp. 327-335, 2015

Authors: Ruan, Jiangjun | Liu, Chao | Liao, Caibo | Du, Zhiye | Zhou, Taotao

Article Type: Research Article

Abstract: There has been a 1000 kV ultra-high-voltage (UHV) AC transmission line running in China, but the related papers introducing the approach path of the helicopter live-line work platform (HLLWP) are still not presented. The model of the HLLWP approaching the transmission lines were established in this paper, based on the real parameters of helicopter MD500 and 1000 kV UHV AC transmission lines. Through calculating electrostatic field with the finite element method, the results of the electric field were obtained when the HLLWP was at different locations nearby a certain phase and approaching different phases. The surface electric fields on the …HLLWP and operator's conductive clothing at different locations were analyzed and then the optimal approaching paths of different phases based on the consideration of the HLLWP and operator's safety were proposed to provide suggestions for the operations of the HLLWP. In the end, the experimental data was compared with the numerical result to prove the reliability of this method. Show more

Keywords: Approaching path, electric field, helicopter, live-line work, platform method

DOI: 10.3233/JAE-140076

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 48, no. 4, pp. 337-344, 2015

Authors: Li, Xiang-Chao | Chen, Puyang | Zhou, Zhongshan | Ye, Ting | Xu, Le | Wang, Chengfang

Article Type: Research Article

Abstract: Surge protective device is widely used in the lightning protection of electric appliances. In order to meet the withstand voltage level of those protected devices, multi-level surge protective devices are applied in the practical situation. Therefore, the optimal choice of decoupling elements is vital to realize the energy coordination between multi-level surge protective devices. This paper intends to expatiate on the process of coordination between these low-voltage multi-level surge protective devices, which is based on the transmission line theory. Through a series of experiments, we found the transmission line theory could be applied to describe the transmission process of lightning …wave in the low-voltage system; When a 5-meter-long wire whose inductance is 5.6 micro-henry was used as the decoupling element, the average shunt ratio between multi-level surge protective device in the first level and multi-level surge protective devices in second was about 0.9: 0.1; upon the experimental results, it was proposed that two voltage limiting type multi-level surge protective devices had a better performance to clamp the overvoltage, which has a certain reference value in the practical application. Show more

Keywords: Surge protective device, transmission line theory, energy coordination

DOI: 10.3233/JAE-140121

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 48, no. 4, pp. 345-356, 2015

Authors: Li, Yuanyuan | Lei, Gang | Sun, Yu | Wang, Li

Article Type: Research Article

Abstract: Magnetic flux leakage inevitably occurs between an axial electromagnetic bearing and a rotor because of the structural arrangement of the former. The effects of magnetic flux leakage of the axial electromagnetic bearing on an active electromagnetic bearing system are studied in this research. Despite the occurrence of a magnetic flux leakage, the axial electromagnetic force produced by the axial electromagnetic bearing is greater than that without magnetic flux leakage at a smaller air gap ratio K (K = 1, 2, 3; where K is the ratio of the air gap between the stator and the rotor to the air gap …between the stator and the thrust plate), and the axial electromagnetic force decreases continuously with the increase in air gap ratio K. When air gap ratio K increases to 4, the axial electromagnetic force with magnetic flux leakage is less than that without magnetic flux leakage. In addition, a deviation is noted between the centers of the rotor and the axial bearing because of machining precision, installation error, or change of running state, and the axial electromagnetic bearing produces additional radial forces on the rotor. The resultant radial force produced by axial electromagnetic bearing increases from 2.1 N to 9.18 N as the radial deviation of the rotor increases from 0.1 mm to 0.4 mm in our simulation conditions. The direction of radial force is the same as that of the radial deviation, which increases the control current of the radial electromagnetic bearing control system and the joule heat of the radial electromagnetic bearing coil. Hence, the additional radial forces produced by axial electromagnetic bearing must be considered in the optimal design of a radial electromagnetic bearing control system. The joule heat of the radial electromagnetic bearing increases from 0.38% to 17.1% because of the additional radial force produced by the axial electromagnetic bearing, which increases the control current of the radial electromagnetic bearing control system. Such increase has an adverse effect on the refrigeration expander, particularly on the cryogenic expander systems in which the bearing is used. Show more

Keywords: Finite element analysis, magnetic flux leakage, radial force, nonlinear

DOI: 10.3233/JAE-140131

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 48, no. 4, pp. 357-366, 2015

Authors: Zhang, Chenyang | Zhao, Shengdun | Han, Xiaolan | Wang, Yongfei | Zhao, Xuzhe

Article Type: Research Article

Abstract: The effects of stirring current and stirring frequency on the microstructure of semisolid AlCu2.4 alloy prepared by electromagnetic stirring (EMS) were investigated. The microstructural evolution of the partial remelting semi-solid AlCu2.4 alloy under different stirring currents, stirring frequencies, and isothermal holding time was also investigated. Results showed that with increased stirring current and frequency, the microstructures of semisolid AlCu2.4 alloy evolved from coarse dendrites to fine, small, and quasi-globular solid particles uniformly distributed among the eutectic. Moreover, after partial remelting, these microstructures became smaller and more spherical and were distributed more evenly with increased stirring current and stirring frequency. When …the stirring parameters were 30 A and 30 Hz, the average grain size was approximately 80 μ m and the shape factor was about 0.76. During partial remelting, both average particle size and the degree of spheroidization constantly increased with prolonged holding time because of Ostwald ripening. The current coarsening rate constant of the semisolid AlCu2.4 alloy prepared by EMS was 567 μm3 s-1 at 590°C. Comparison between the present work and other literature results indicated that the coarsening rate was associated with the microstructure prior to partial remelting, as well as with the alloy composition. Show more

Keywords: Aluminum alloy, semisolid, microstructure, electromagnetic stirring

DOI: 10.3233/JAE-140139

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 48, no. 4, pp. 367-378, 2015

Authors: Zhang, Zhi-Ya | Huang, Peng | Zuo, Shao-Li | Zhao, Jia-Yue | Fu, Guang

Article Type: Research Article

Abstract: A circularly polarized (CP) spiral antenna array for wideband application is presented, which employs a simple single-arm spiral antenna (SASA), as the radiating element. By introducing a small round disc backed near the antenna center and loading a termination resistor, the SASA achieves a wide impedance bandwidth without a balun circuit and a good axial ratio (AR) performance, respectively. A total of four array elements are used in the 2 × 2 configuration to obtain a higher gain. Particularly, a method of sequentially rotating the elements is used to improve the axial ratio. The array performs an impedance bandwidth for …VSWR ≤ 1.5 of 40% ranging from 1.25 to 1.88 GHz, an excellent AR of better than 0.74 dB, and a gain variation from 11.34 to 14.56 dB within the operating band. Measured and simulated results presented for the array confirm its wide impedance, axial ratio, and gain bandwidths. Acceptable agreement between the simulation and measured results validates the proposed design. Show more

Keywords: Circular polarization, array antenna, spiral antenna, wideband antenna

DOI: 10.3233/JAE-140151

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 48, no. 4, pp. 379-386, 2015

Authors: Belounis, A. | Mehasni, R. | Ouili, M. | Latreche, M.E.

Article Type: Research Article

Abstract: In this work, we present a 3D approach for the optimization of the capture element for an open-gradient magnetic separation (OGMS) used for the purification of flowing liquids in a channel of small diameter D = 2.5 × 10-2 m. This optimization is concerned with the research of the capture element design and the excitation current that allow the separation of ferromagnetic particles of fine size Rp = 3 × 10-5 m. The proposed approach is based on the minimization of an objective function which is the distance between the particle capture site and the central point …of the capture element assumed to be the perfect capture site. To obtain the particle capture site we have computed its behavior where the important magnetic and hydrodynamic applied forces have been taken into account. To perform the minimization of the objective function, we have applied the Tabu search method. To validate the obtained results, experiments have been performed on a flowing water containing particles of iron. Such validation has dealt with the verification of the capture site and the quantification of the volume of the separated particles buildup. Show more

Keywords: Interdisciplinary applications of physics, magnetic separation, magnetic device characterization, particle dynamics, optimization.

DOI: 10.3233/JAE-140157

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 48, no. 4, pp. 387-397, 2015

Authors: Yang, Bo | Zhang, Qi | Jiang, Zhidong

Article Type: Research Article

Abstract: The two-step finite-difference time-domain method of solving full-wave Maxwell's equations is adopted to analyze the lightning electromagnetic pulse (LEMP) coupled to shielding enclosure with different apertures. The coupled field at different positions in the shielding room is calculated. The results suggest that the shielding enclosure can attenuate most of LEMP energy at its center even if there are some apertures on the shielding room. However, in the shielding enclosure the coupled LEMP is still rather strong near the apertures. Furthermore, both the size and direction of the slots on the shielding enclosure strongly affect the coupled field.

Keywords: Aperture coupling, lightning electromagnetic pulse, shielding enclosure, two-step finite-difference time-domain method

DOI: 10.3233/JAE-140182

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 48, no. 4, pp. 399-408, 2015

Authors: Zhou, Jinzhu | Song, Liwei | Huang, Jin | Wang, Congsi

Article Type: Research Article

Abstract: This paper proposes a coupling approach to investigate the effects of dynamic loads on the performance of structurally integrated antenna. In this method, the deformed displacement of radiating elements is determined by using the modal superposition principle of dynamic mechanic equation. Subsequently, the deformed displacement is coupled to the radiated field equation of the antenna array considering the effect of mutual coupling. Finally, an electromechanical coupling model is built by combining the equations from two different disciplines. An iterative solution method is presented to solve the coupling model. Some experimental devices are designed by utilizing a 2.5 GHz structurally integrated …antenna, and the results confirm the effectiveness of the coupling model. The validated model is applied to investigate the influences of dynamic loads on the mechanical and electrical performance. The results show that the deformed displacement of radiating elements depends on the structural constraint forms and dynamic load values. Moreover, the greater the deformed displacement of the antenna array surface, the more serious the degradation of the electrical performance. The coupling model is particularly suited to the multidisciplinary analysis and design of structurally integrated antenna. Show more

Keywords: Structurally integrated antenna, electromechanical coupling, deformed displacement, mutual coupling

DOI: 10.3233/JAE-140184

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 48, no. 4, pp. 409-422, 2015