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

Authors: Li, Ping | Gao, Shiqiao | Cai, Huatong | Cui, Yan

Article Type: Research Article

Abstract: MEMS piezoelectric energy harvester is optimally designed and fabricated, and its vibration characteristics, output voltage, power, power spectral density (SD) and frequency response function under harmonic and random excitation is studied by theory analysis, simulation and experimental test. For the designed MEMS piezoelectric energy harvester, the accurate solutions and expressions of amplitude, voltage, power and power spectral density are derived. Then, vibration characteristic, voltage, power and power SD with different load resistance, …sinusoidal acceleration and random acceleration SD are simulated and tested; moreover, frequency response function of MEMS piezoelectric energy harvester is obtained by experimental test, and the results are consistent with theoretical model. When sinusoidal acceleration is 0.6 g, the maximal amplitude of mass is 116 μm and the power density is 0.1 mW/cm^{3} . By testing results, output voltage of piezoelectric energy harvester is proportional to the amplitude, and the amplitude at optimal load is smaller than of at open circuit because of the feedback effect of load resistance. In addition, output power SD linearly increases with acceleration SD increasing. When acceleration SD is 5 × 10^{-4} (m/s^{2} )^{2} /Hz, power SD is 1.24 μW^{2} /Hz. Show more

Keywords: MEMS energy harvester, amplitude, random excitation, frequency response function

DOI: 10.3233/JAE-140002

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 125-139, 2015

Authors: El-Kharashi, Eyhab

Article Type: Research Article

Abstract: Most of the electrical machines designed to have their stators on the outside and their rotors on the inside. However, it was noticed that the shaft fills a relatively high volume inside the machine without producing any torque. That means there is a wasted volume within the machine and this volume does not produce any torque. From this point of view, there are some trends in designing and building electrical machines to have their rotors outside the …machine and their stators inside the machine. Here the example used for the machines using those designs is the permanent magnet (PM) machine, which is an electrical machines designed by the two different methods, inner and outer rotors to be used in many applications such as wind turbines and electric vehicle wheel motors. This paper is dedicated to prove that the external rotor permanent magnet machine is preferred for some significant reasons. The paper uses two approaches to demonstrate that. The first approach is using the geometrical volume of each machine to compare the torque capabilities in case of two possible topologies of the PM machines. The second approach is to compare the PM machine with another type of electrical machine, that has the same magnetic circuit topology and the rotor can be inside and outside as well. Show more

Keywords: Permanent magnets machine, outer rotor, inner rotor, geometric approach, segmented rotor

DOI: 10.3233/JAE-140003

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 141-152, 2015

Authors: Wang, Tao | Wang, Qingfeng

Article Type: Research Article

Abstract: Electro-hydraulic power units are key components of hybrid driven mobile machines such as forklifts and excavators. To satisfy the requirement of limited installation space, this paper proposes a compact and reversible electro-hydraulic energy conversion unit which is the integration of an axial piston hydraulic pump/motor and an electrical machine excited by a segmented Halbach permanent magnet array. The magnets are fixed on the surface of a barrel so that the hydraulic rotor and the electrical rotor …are integrated together. Analytical and numerical methods are used to investigate the coupling issues including the common rotor's effect on flux density distribution, combined torque ripple, flow and energy losses in the oil gap, and some design criteria are presented to provide further development with references. Show more

Keywords: Electro-hydraulic, structure integration, halbach array, energy conversion, coupling effect

DOI: 10.3233/JAE-140004

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 153-162, 2015

Authors: Singh, Ashish | Ansari, J.A. | Kamakshi, Dr. | Aneesh, Mohd. | Sayeed, Saiyed Salim

Article Type: Research Article

Abstract: In this article, analysis of slot loaded compact rectangular patch antennas have been presented theoretically using circuit theory concept. The theoretical investigations of L-strip fed slot loaded compact rectangular microstrip patch antenna parameters such as return loss, VSWR, radiation pattern have been calculated. It is found that antenna resonates at 2.95 GHz and 6.01 GHz for lower and upper resonance frequencies respectively. The bandwidth of the L-strip fed slot loaded compact rectangular microstrip patch …antenna at lower resonance frequency is 1.16% (simulated) and 10.16% (theoretical) whereas at upper resonance frequency, it is 1.5% (simulated) and 2.51% (theoretical). The characteristics of the L-strip fed slot loaded compact rectangular microstrip patch antennas is compared with other rectangular patch antennas. Circuit diagram of this antenna is proposed, fabricated and simulated using AWR circuit simulator. The theoretical results are compared with IE3D and AWR simulation results along with measured results and they are in close agreement. Show more

Keywords: Microstrip patch antenna, dualband, slot, L-strip, shorting pin

DOI: 10.3233/JAE-140020

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 163-175, 2015

Authors: Wang, Xiuchen | Liu, Zhe | Zhou, Zhong

Article Type: Research Article

Abstract: Though electromagnetic interference (EMI) shielding fabric with rectangular hole has wide application in various fields, there is not a mature approach to calculate its shielding effectiveness (SE) at present. This paper constructs a rapid computation model of the SE of the EMI shielding fabric with hole based on equivalent coefficient. Firstly, the rectangular hole characteristic is analyzed and a structure model of the rectangular hole under the consideration of the hole edge characteristic is described. The …equivalent relationship between the fabric hole and the standard hole is presented according to the equivalent theory. The rapid computation model of the SE of the EMI shielding fabric with hole is built including the equivalent coefficient and transmission coefficient according to the EMI shielding theory and the method to determine the equivalent coefficient is also given. Finally, the computation model is verified by experiments. The results show that the accuracy and the computational efficiency of the proposed model are good, and the model can be applied to the fabrics with wide weaves and various rectangular hole sizes. Show more

Keywords: Hole, electromagnetic interference shielding fabric, shielding effectiveness, computation model

DOI: 10.3233/JAE-140023

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 177-185, 2015

Authors: Jung, Kwang Suk

Article Type: Research Article

Abstract: An axial magnet wheel, in which permanent magnets are arranged circumferentially and polarized periodically, is proposed as a driving method to transfer a conductive rod without mechanical contact in space. The magnet wheel, whose axial plane is laid parallel to the rod, is rotated to generate three axial magnetic forces on the rod. But, the all forces are strongly coupled to each other through the rotational speed of the wheel. Furthermore, the number of degrees of …freedom to be controlled in the transfer system, in which the rod is supported by two pairs of magnet wheels actuated by two wheel motors, is more than the number of input variables. To solve the above problem, a novel method in which the transfer control of the rod is converted to a tilt control of the rod is proposed and verified experimentally. And, the force characteristic of the magnet wheel is analyzed for variations of the main geometric parameters to obtain the desired design specifications. Show more

Keywords: Conductive rod, electrodynamic force, independent control, magnet wheel, noncontact conveyance

DOI: 10.3233/JAE-140026

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 187-197, 2015

Authors: Liao, Yaoyao | Lian, Zisheng | Long, Risheng | Yuan, Hongbing

Article Type: Research Article

Abstract: The large flow electro-hydraulic directional valves are the key operating components for automation of the hydraulic roof supports in the coal mine. Cracking is a common failure mode of the valve. Effects of the buffer damp diameter, the valve type and the static pressure on the stress of the valve were researched. The valve dynamic behavior was investigated by AMESim. The transient collision stresses of the inlet valve sleeve of the main control valve under different …buffer damp diameters and different valve types were investigated by ANSYS/LS-DYNA. The static stress analysis was conducted in ANSYS too. Results show that the valve failure is due to the fatigue of the inlet valve sleeve when suffered from the collision stress wave in the valve opening process, rather than the lack of component strength. The buffer damp diameter, the key parameter of the valve, has a significant effect on the collision stress of the inlet valve sleeve. The integrated type valve has a better stress state compared to the separated type valve. This paper provides an effective method to solve the fracture problems of hydraulic directional valves. It is also significant for the design and optimization of hydraulic components. Show more

Keywords: Electro-hydraulic directional valve, stress analysis, fatigue, collision, hydraulic roof support

DOI: 10.3233/JAE-140028

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 199-209, 2015

Authors: Lin, Chih-Hong

Article Type: Research Article

Abstract: Due to V-belt continuously variable transmission (CVT) driven electric scooter with unknown nonlinear and time-vary characteristics, an accurately dynamic modeling of V-belt CVT driven electric scooter is the time-consuming procedure for the linear controller design. A hybrid modified recurrent Legendre neural network (NN) control system is proposed to control the V-belt CVT driven electric scooter under the occurrence of nonlinear load disturbances with parametric variations in order to acquire good control performance. …Firstly, system structure of the V-belt CVT driven electric scooter by using a permanent magnet synchronous motor (PMSM) servo drive system is proposed in this study. Secondly, the hybrid modified recurrent Legendre NN control system, which consists of an inspector control, a modified recurrent Legendre NN control with adaptive law and a recouped control with estimated law, is proposed to control the V-belt CVT driven electric scooter by using PMSM servo drive. Moreover, the on-line parameters tuning methodology of the modified recurrent Legendre NN is derived according to Lyapunov stability theorem and gradient descent method. Furthermore, two optimal learning rates of the parameters in the modified recurrent Legendre NN are developed to speedup convergence. Finally, to show the effectiveness of the proposed control scheme, comparative studies are demonstrated by simulated and experimental results. Show more

Keywords: Continuously variable transmission, electric scooter, permanent magnet synchronous motor, modified recurrent legendre neural network, lyapunov stability

DOI: 10.3233/JAE-140035

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 211-235, 2015

Authors: Ashraf, Faheem | Ahmed, Shakeel | Syed, A.A. | Naqvi, Q.A.

Article Type: Research Article

Abstract: We study the scattering of time harmonic electromagnetic plane wave from a topological insulator circular cylinder in chiral medium. Variation of scattering behavior for different values of radii and permittivity of the cylinder is noted when time reversal symmetry is protected and we also studied the scattering behavior when time reversal symmetry is broken. Although scattering behavior of co-polarized component of field is not significantly different from chiral cylinder in chiral medium yet it is found …that the same, when time reversal symmetry broken, is similar to scattering from a perfect conductors. Scattering behaviour of cross-polarized field component of topological cylinder in chiral medium is remarkably different from chiral cylinder i.e. it has stronger scattering possibly due to the presence of conducting states near the surface. Moreover, it is noted that the scattering in forward direction for cross-polarized and co-polarized components are not correlated with permittivity but for carefully selected values of permittivity, we can control the scattering behavior of topological insulator circular cylinder. Show more

Keywords: Topological insulator, chiral medium, circuar cylinder, time reversal symmetry, time harmonic electromagnetic waves, scattering

DOI: 10.3233/JAE-140039

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 237-244, 2015

Authors: Jiang, Shunong | Du, Jinlong

Article Type: Research Article

Abstract: Attached masses are utilized in this work to improve the performance of circular cylindrical piezoelectric transformers operating in thickness-shear mode. An exact solution based on the linear theory of piezoelectricity is obtained to verify the concept. The transforming ratio, displacement and stress fields of the transformer are investigated. Numerical results based on the theoretical analysis show the noticeable influences of the attached masses on the behavior of the transformer. The desirable load impedance for a high …transforming ratio is also obtained in this study. Show more

Keywords: Piezoelectric transformer, thickness-shear mode, transforming ratio

DOI: 10.3233/JAE-140043

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 245-253, 2015