International Journal of Applied Electromagnetics and Mechanics - Volume 48, issue 1

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

Article Type: Research Article

Abstract: Space debris is considered as a serious threat to man's utilization and exploration of space. While some information is available on the material composition of orbital debris, most measurements of projectile size and velocity distributions can not distinguish material compositions and type. The analysis and understanding of impact flash signatures can determine projectile's size and impact velocity distributions for projectile segregated by material composition and type. This paper based on the derivation of the shock jet initiated model for light flash and an understanding of how material shock properties govern the flash signature arising from the impact of a spherical …projectile against a target. Analytical results are presented that identify the most promising target materials with respect to producing impact flash signatures that can characterize size effect of spherical projectile, impact angle and impact velocity effects during LY12 aluminum projectile hypervelocity impact LY12 aluminum spacecraft shield material. Show more

Keywords: Hypervelocity impacts, LY12 aluminum projectile, light flash, projectile's size and impact velocity effects, pyrometer

DOI: 10.3233/JAE-140036

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 48, no. 1, pp. 1-9, 2015

Authors: Ning, Yinhang | Liu, Chuang | Zhu, Shushu | Tang, Jie

Article Type: Research Article

Abstract: The paper presents a hybrid excited synchronous generator (HESG) with field windings and permanent magnets. This paper focuses on the analysis in the operating principle, rotor shape optimization, and inductance characteristic, based on finite element method. The measured voltage waveforms suggest that the rotor shape optimization in the study is a feasible solution to improve the quality of output voltage. Both the simulation and the tested results on generator performance verify further that the electric excitation can efficiently adjust the air-gap flux. Compared to conventional electric excited synchronous generator, the load capacity is improved due to relatively low armature inductance …of the HESG. Show more

Keywords: Hybrid excitation, synchronous generator, cogging torque, rotor pole optimization, inductance, air-gap flux regulation

DOI: 10.3233/JAE-140116

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 48, no. 1, pp. 11-19, 2015

Authors: Xu, Lizhong | Wang, Zhichong

Article Type: Research Article

Abstract: The micro resonant pressure sensor is attractive because it outputs the frequency signals. As the dimensions of the sensor decreases, the effects of the van der Waals forces and the electrostatic forces on its dynamics performance should be considered. It is a multi-field coupled dynamics problem. Here, the dynamic equations of the micro resonant beam for the micro resonant pressure sensor under multi-field coupled situations are deduced. Using these equations, the effects of the van der Waals force or the electrostatic force on the natural frequencies of the micro resonant beam are investigated. The effects become more obvious under certain …conditions. The results are useful to improve design about dynamics performance for the micro resonant pressure sensor. Show more

Keywords: Multi-field coupled, free vibration, micro resonant pressure sensor, natural frequency

DOI: 10.3233/JAE-140128

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 48, no. 1, pp. 21-31, 2015

Authors: Xiang, Jintao | He, Siyuan | Zhang, Yunhua | Zhu, Guoqiang

Article Type: Research Article

Abstract: A method for the calculation of the scattering of the stratified uniaxial electric anisotropic media (UEAM) under point source excitation with arbitrary orientation is presented. In this method, the total field is decomposed into three parts, the radiated field of the point source in free space, the reflected field from the top interface of the UEAM and the transmitted field after multiple reflections in the anisotropic layer. The three parts are derived in spectral domain respectively and can be expressed by using Fourier transform. Then the saddle point technique (SPT) is introduced to obtain an asymptotic solution of the scattered …field. Results from the asymptotic solution are compared with the results calculated by the method of moments (MOM) and the comparison shows good agreement. Show more

Keywords: Point source, scattering, uniaxial electric anisotropic, spectral domain method, saddle point technique

DOI: 10.3233/JAE-140145

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 48, no. 1, pp. 33-46, 2015

Authors: Lin, Ling | Weng, Chun-Sheng

Article Type: Research Article

Abstract: The technology of magnetohydrodynamic (MHD) acceleration has received significant attention due to its wide application prospect in aeronautics and astronautics. With the development of MHD acceleration, thrust of pulse detonation engines can be increased by MHD augmentation. In the pulse detonation induced MHD ejector (PDIME) concept, under-expanded flow at the exit of converging-diverging nozzle propagates upstream into the bypass tube. The seeded air stream in the bypass tube is first shocked and raises to high-temperature to ionize thermally. The magnetic field energy is appended to accelerate the ionization gas in bypass tube, thus augments the propulsive performance of PDE. In …this paper, the model of gas-liquid two-phase detonation engine with bypass was established. The engine was ignited by plasma jet. Conservation Element and Solution Element (CE/SE) method was deduced to solve plasma jet ignition and detonation process with MHD accelerator. The computational results show that the deduced CE/SE method can be efficient to capture discontinuity such as the shock at the appliance of PDIME. It has been observed that thrust augmentation can be accomplished by the bypass accelerator, even the bypass accelerator will activate originally only under a given magnetic field intensity and diameter of the bypass tube. Further analysis and optimization are required to improve performance. The results have certain significant reference for the experimental study in future. Show more

Keywords: Pulse detonation engines, plasma jet ignition, MHD augmentation, the CE/SE method

DOI: 10.3233/JAE-140179

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 48, no. 1, pp. 47-57, 2015

Authors: Liu, Xiquan | Fang, Jiancheng | Zheng, Shiqiang

Article Type: Research Article

Abstract: The electrical frequency of high speed permanent magnet motor leads to pronounced parasitic effects, such as skin, proximity and circulating current effects. The parasitic effects result in uneven distribution of currents and the increase of the ac resistance of the winding. Ac resistance is proportional to the winding loss and the ratio of ac resistance of winding to dc resistance of winding is used to characterize the winding loss. The parameters of winding, as well as the parameters of slot dimensions of stator, will affect the degree of parasitic effects. The influences of some design parameters are analyzed in this …paper. Show more

Keywords: Winding loss, high speed permanent magnet motor, low voltage, high frequency, parasitic effects

DOI: 10.3233/JAE-140189

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 48, no. 1, pp. 59-67, 2015

Authors: Rybin, Oleg

Article Type: Research Article

Abstract: A quantitative concept of miniaturization of a narrow-band rectangular patch antenna by using a metamaterial substrate with a large value in the real part of the effective permittivity instead of a conventional homogenous high dielectric material is proposed in the microwave frequency range. The volume of the antenna is minimized by tuning the relative permittivity and thickness of the substrate material. The specific type of composite that can be used as substrate material and result in antenna miniaturization is suggested. Possible applications of the concept are discussed.

Keywords: Composite, substrate, narrow band patch antenna, microwaves, miniaturization

DOI: 10.3233/JAE-140197

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 48, no. 1, pp. 69-75, 2015

Authors: Ghandehari, Mehdi Bahdorzadeh | Feiz, Nooshin | Khazaei, Ali Akbar

Article Type: Research Article

Abstract: A novel metamaterial absorber (MA) based on triple hexagonal shaped resonators has proposed in this paper. This metamaterial unit cell absorber possesses a nearly wide angle perfect absorption of incidence wave and polarization independence. The absorption is occurred in three different frequencies. The absorptivity is as high as 94%, 95% and 99%, at 3.4 (GHz), 4.6 (GHz) and 6.4 (GHz), respectively. An important feature of this metamaterial absorber is easy fabrication and maximum absorption is observed in three different frequencies. The proposed metamaterial absorber has wide applications such as stealth technology, thermal detector and imaging. Moreover, a very good agreement …between simulation and measurement results has been observed. Show more

Keywords: Metamaterial absorber, triple band, wide angle independent

DOI: 10.3233/JAE-140180

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 48, no. 1, pp. 77-83, 2015

Authors: Long, Yongjun | Chen, Xinshu | Wang, Chunlei | Wei, Xiaohui | Mo, Jinqiu | Wang, Shigang

Article Type: Research Article

Abstract: This paper considers the pull-in of electromagnetic actuator with permanent magnet for the first time. The pull-in mechanism of electromagnetic actuator is explained from the perspective of system stiffness. Pull-in is about to occur when system stiffness becomes null. Based on the system stiffness analysis method, the pull-in parameters of an E-core electromagnetic actuator with permanent magnet are derived. Then, the effects of the permanent magnet on the derived pull-in parameters are studied. The analysis results show that the permanent magnet enlarges the pull-in displacement for its reluctance. If the permanent magnet length is more than three times as large …as the initial displacement, pull-in would not occur. The effects of the permanent magnet on the pull-in current are complicated, especially the effects of the permanent magnet length. A method based on analyzing the roots of two properly defined equations is introduced to study the effects of the permanent magnet length on the pull-in current. The method is effective and simplifies the complicated analysis. Finally, numerical simulations are presented to validate the pull-in model and analysis methods in this paper. It is shown that the theoretical results are in a good agreement with the simulation results. Show more

Keywords: Pull-in, permanent magnet, electromagnetic actuator, system stiffness

DOI: 10.3233/JAE-140033

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 48, no. 1, pp. 85-100, 2015

Authors: Wang, Zhongzhong | Li, Decai

Article Type: Research Article

Abstract: A new experimental setup was designed in order to study the loading process among stages of magnetic fluid seal. Magnetic field distributions under the pole pieces of the magnetic fluid seal with six stages were simulated by finite element method, and the results proved its rationality. A series of tests on experimental setup were run in order to study the way of pressure transmission among stages of magnetic fluid seal and to extend our knowledge on the mechanism of seal operation. The results of the experiments not only proved the correctness of the corollaries of previous researchers and more detailedly …shows the way of pressure transmission in each stage. A mathematical model of the way of pressure transmission among stages of magnetic fluid sea was constructed by previous inference and the present experimental results, and it is able to express the specific way of pressure transmission at certain extent. The experimental conclusion also shows that the quantity of magnetic liquid in each stage will be redistributed and the quantity of magnetic liquid in each stage may be unevenly distributed when the pressure of the pressure chamber is imposed. It has a certain value of reference in the improvement of design and structure process of magnetic fluid seal in engineering problem. Show more

Keywords: Magnetic fluid seal, loading process of stages, pressure transmission

DOI: 10.3233/JAE-140126

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 48, no. 1, pp. 101-110, 2015