International Journal of Applied Electromagnetics and Mechanics - Volume Pre-press, issue Pre-press

Authors: Wu, Jiamin | He, Yucheng | Shen, Sheng | Guo, Pan | Huang, Xin | Xu, Zheng

Article Type: Research Article

Abstract: Traditional nuclear magnetic instruments are not convenient for measurement in situ due to the closed magnet structure and heavy weight. It is crucial to improve tree planting by exactly detecting moisture parameters of living trees. To investigate this problem, an open and portable magnetic resonance sensor was proposed. In this work, we introduced unilateral magnetic resonance sensor which can achieve onsite nondestructive measurement of large-volume samples due to its open structure. To fit the shape of living trees, the region of interest was set in an arc region. A magnet structure was optimized by ANSYS software. Because the magnet has …a constant natural gradient along radial direction, we need gradient fields in the other two directions (Z and Y). Z/Y gradient coils for unilateral magnetic resonance sensor are studied based on the Fourier series method. Current density in gradient coils is assumed as Fourier series composed of trigonometric functions. We introduced stream function to establish relationship between the current density and the winding structure, then constructed an optimization model by combining power dissipation with the deviation between calculated field and target field. The coils are manufactured using a flexible printed circuit board and measured by gauss meter. The measurement and simulation results are consistent. Measurement results of the gradient coils showed that the magnetic fields have good linearity which is helpful to realize 3D measurement in the upcoming work. Show more

Keywords: Unilateral magnetic resonance, Fourier series method, gradient coil design

DOI: 10.3233/JAE-190076

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-13, 2019

Authors: Liu, Bingcheng | Liu, Ning | Wang, Shaoyi | Jia, Wenguang

Article Type: Research Article

Abstract: Magnetic induction intensity and current are crucial factors to determine the effect of electromagnetic anti-fouling technology (EAFT). For getting the current value in the coil which was tightly wrapped around the PVC pipe, the inductance and equivalent resistance of the coil was measured by LCR meter, and the current in the circuit of the anti-fouling system was obtained by Ohm’s law. The magnetic induction intensity in the solenoid centre can be calculated by Faraday’s law. The purpose of the experiment was to find the optimal output parameters of EAFT and explored the anti-fouling effect. Therefore, we established an experimental platform …to optimize the output parameters and explore the effect of different output frequency on solution conductivity and particle diameter. Through experiments, it’s found that current in the coil was reduced with increasing frequency, the number of turns and the diameter. As the frequency and diameter increase, the magnetic induction intensity reduced, and the turns basically no impact on the magnetic induction intensity. The hardness solution of 10 mol ⋅ m−3 (as CaCO3 ) is treated by four different frequencies electromagnetic field shows that the lower the frequency, the greater decrease in conductivity and the greater increase in particle size, that phenomenon verifying that the higher current and stronger magnetic field intensity has a better anti-fouling effect. Show more

Keywords: Electromagnetic anti-fouling technology, current, magnetic induction, conductivity, particle diameter

DOI: 10.3233/JAE-190055

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-13, 2019

Authors: Gong, Qi | Zhang, Weiwei | Su, Yufeng | Zhang, Kun

Article Type: Research Article

Abstract: In this paper, a diamagnetic-airflow hybrid levitation structure is reported, with a floating magnet rotor stably levitated above a diamagnetic disc just using a lifting magnet and airflow. Compared with the typical diamagnetically stabilized structure, the rotation speed of the rotor is increased from 9570 rpm to 16666 rpm, and the levitation gap is increased from 0.3 mm to 0.7 mm when the airflow rate exceeds 2198 sccm under standard temperature and pressure (STP). At the same time, the rotor can be stably levitated at any height from 0.2 mm to 0.8 mm by adjusting the vertical position of the nozzles. With the hybrid levitation structure, it’s …possible to overcome the structural limitation of typical diamagnetically stabilized levitation structure and enhance the working performance of the rotor. This levitation structure is expected to be applied to sensing, energy harvesting and air bearing under actuation of airflow. Show more

Keywords: Diamagnetic, airflow, stabilized levitation, simulation, energy harvesting

DOI: 10.3233/JAE-190081

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-14, 2019

Authors: Mingliang, Zheng

Article Type: Research Article

Abstract: In this paper, the Lie symmetry theory of singular mechanico-electrical coupling systems is studied in phase space. Firstly, the Hamilton canonical equation of singular mechanico-electrical coupling systems is established through energy; Secondly, considering the inherent constraints brought by singularity, the determining equations, definitions, structural equations and conserved quantities of Lie symmetry are all given; Finally, an application example is given. It is shown that if the structural equation of Lie symmetry is just right the criterion equation for Noether symmetry, then the Lie symmetry can lead to the conserved quantity of Noether type; if the structural equation of Lie symmetry …does not involve the Hamiltonian function, the conserved quantity of non-Noether type can be obtained only through finding the invariant of symmetric group. Show more

Keywords: Singular mechanico-electrical coupling systems, Lie symmetries, structural equations, conserved quantities

DOI: 10.3233/JAE-190059

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-9, 2019

Authors: Shi, Yan | Lin, Cong | Lu, Bin

Article Type: Research Article

Abstract: Electromagnetic linear actuator (EMLA) is an alternative of the conventional damper in vehicle suspensions and harvests suspensions vibration energy which is wasted generally. Due to large variations of its Back Electromotive Force (Back-EMF), it will thus be interest to investigate how to recycle the electricity efficiently. In this paper, to improve the recycling efficiency of the EMLA, a feedback energy circuit featured with combination of parallel switchover supercapacitors technology and a boost-buck DC-DC converter is proposed on the basis of the generating characteristics of a newly designed EMLA. By modeling the feedback energy circuit, its dynamic characteristics are simulated and …its efficiency is investigated. The results of simulations and experiments show that the feedback energy circuit can achieve a wide range of energy recovery regardless of large variations of Back-EMF induced by the EMLA. Simultaneously, by keeping the boost-buck ratio less than 3, the efficiency of energy recovery is high, in some cases could reach 94%. Show more

Keywords: Energy harvesting, electromagnetic linear actuator, active suspensions, feedback energy circuit

DOI: 10.3233/JAE-180135

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-15, 2019

Authors: Liu, Yafeng | Wang, Xinjie | Wang, Jiong | Chen, Hejuan

Article Type: Research Article

Abstract: The lanthanum-doped lead zirconate titannate (PLZT) ceramic has shown its potential applications as light-controlled micro actuators activated by ultraviolet light for the photovoltaic effect in the field of micro-driven. Aiming to the slow response of photostriction of PLZT ceramic, the primary purpose of this article is to propose a light-controlled actuator with the novel opto-electrostatic hybrid driving based on PLZT ceramic. The mathematical model of the proposed light-controlled actuator is established on basis of the anomalous photovoltaic effect model of PLZT ceramic. The actuation characteristics of the micro actuator are investigated based on the established mathematical model and the experiments …of the photovoltage of PLZT ceramic. Furthermore, the actuation curves of the micro actuator driven by opto-electrostatic hybrid driving based on PLZT ceramic are acquired to verify the rationality and feasibility of the light-controlled micro actuator design. So according to the analysis and experimental results, the light-controlled actuator driven by the novel opto-electrostatic hybrid driving based on PLZT can conduct the effectively and precisely displacement control with fast response speed. In addition, the driving method based on the novel opto-electrostatic hybrid driving has advantages of non-contact control, remote control and no electromagnetic interference, etc. Show more

Keywords: PLZT, micro actuator, opto-electrostatic hybrid driving, light-controlled

DOI: 10.3233/JAE-190035

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-12, 2019

Authors: Li, Zhao | Yan, Li | Qu, Boyang | Fu, Kai

Article Type: Research Article

Abstract: In this paper, an analytical model is proposed to predict the magnetic field and torque characteristics of flux-concentration cage-type eddy-current couplings with slotted conductor rotor topology. Due to the presence of discontinuous boundary conditions in permanent magnet rotor domain and conductor rotor domain, the accurate sub-domain method is employed in polar coordinates. The permanent magnet domain and the conductor domain are divided into different sub-domain according to the number of poles and slots. The magnetic vector potential in each domain is obtained by solving the field equation based on the separated variable method. Then the magnetic field distributions and output …torque are computed. By using the nonlinear 2D and 3D finite element analysis, the validity of such model is proved, and the cause of deviation is discussed. In the end, the proposed formula is used for a design optimization using particle swarm optimization algorithm. Show more

Keywords: Eddy-current couplings, sub-domain method, finite-element method, design optimization

DOI: 10.3233/JAE-190056

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-19, 2019

Authors: Zhang, Yuyang | Leng, Yonggang

Article Type: Research Article

Abstract: Magnets are widely used in many fields, both industry and our daily life, because of their unique properties such as non-contact interactions and electricity generation. However, behaviors of permanent magnets seem to deviate from our basic understanding that opposite poles attract and like poles repel. We have recently discovered an interesting phenomenon in pairs of permanent magnets with large different sizes where the like poles do not seem to repel and the unlike poles do not seem to attract with each other, due to a localized area with reversed pole existing in the large permanent magnet. In this paper, we …first experimentally confirm the existence of this particular phenomenon by studying interactions of several groups of permanent magnets with different sizes, then we introduce the property of the irreversible movements of load line and working point of permanent magnet to figure out this transition process from repulsion to attraction between a pair of permanent magnets with large different sizes. A reasonable explanation is finally given. In the end, we suggest a few applications for this special phenomenon. Show more

Keywords: Magnetic force calculation, load line, demagnetizing field, working point

DOI: 10.3233/JAE-190057

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-15, 2019

Authors: Wu, Jie | Hu, Hong | Liang, Jian

Article Type: Research Article

Abstract: This paper investigates the magnetic circuit model of a multi-pole multi-layer magnetorheological (MR) brake. Firstly, a simple introduction to the structure is given. This MR brake has a unique structure design with several MR fluid working gaps set between two-layer coils. Then, magnetic circuit model is conducted to theoretically approximate the effects of the design parameters on the magnetic field strength within the MR fluids. According to the magnetic circuit analysis, a parametric study is performed to optimize the critical design parameters of the magnetic circuit of the designed brake. Finally, the magnetic circuit model is validated based on the …optimized structure and simulation. Simulation results indicate that the magnetic circuit model is feasible to estimate the magnetic field strength in the working gaps, and it can be used to guide the parameters optimization and structure design. Show more

Keywords: Magnetorheological (MR) brake, magnetic circuit, modeling, finite element analysis, optimization

DOI: 10.3233/JAE-190025

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-24, 2019

Authors: Liu, Qing | Wang, Li | Zhang, Shiping | Wang, Xinjie | Yu, Chengyu | Lei, Gang

Article Type: Research Article

Abstract: Based on the non-contact characteristics, active magnetic bearings (AMBs) possess great benefits like no lubrication, high speed, high accuracy and long lifespan. Moreover, the rotor dynamic performance is adjustable and working conditions are monitorable. Nonetheless, AMBs suffer from large power loss and rotor heating. One viable approach is omitting the bias current, i.e., zero-bias AMBs, but this also results in high non-linearity and poor controllability. The common control practices of zero-bias AMBs are based on nonlinear models, for there is only one electromagnet being electrified at any moment to produce a net control force. Here, we propose a linear control …strategy for zero-bias AMB. Assuming that each coil has an average current proportional to the pulse width modulation (PWM) duty cycle, the quantitative relation among the magnetic force, the rotor displacement and the coil current can be acquired. Further, this control algorithm was applied to both the horizontal and the vertical thrust zero-bias AMBs. Experimental results proved the existence of currents in both electromagnetic bearings in the unbalanced state. And the rotor-bearing system restored rapidly to an equilibrium state after sudden disturbances. Overall, this method demonstrates the transition from physics to engineering and shows a good application prospect. Show more

Keywords: Zero-bias magnetic bearing, mathematical model, quantitative control, PWM, power consumption

DOI: 10.3233/JAE-180127

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-22, 2019