International Journal of Applied Electromagnetics and Mechanics - Volume 42, issue 2

Authors: Xu, Lizhong | Li, Huaiyong

Article Type: Research Article

Abstract: The Authors propose an electromechanical integrated harmonic piezodrive system in which the piezodrive principle is combined with the harmonic drive and the movable tooth drive principles. The free vibration behavior of the flexible ring has important effects on operating performance of the drive system. Here, the dynamic equations for the harmonic piezodrive system are deduced. The natural frequencies and dynamic displacements of the drive system are investigated. Results show that a large length of the flexible …ring, a small thickness of the flexible ring should be selected, and the flexible ring should be made with Cu in order to obtain better operating behavior of the drive system. These results are useful in design and manufacture of the drive system. Show more

Keywords: Electromechanical integrated, harmonic piezodrive, dynamic displacement, natural frequency

DOI: 10.3233/JAE-131663

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 2, pp. 269-282, 2013

Authors: Awasthi, Mukesh Kumar | Asthana, Rishi | Agrawal, G.S.

Article Type: Research Article

Abstract: The linear analysis of Kelvin-Helmholtz instability of the interface between two viscous fluids in the presence of horizontal electric field has been carried out when there is heat and mass transfer across the interface. The viscous correction for the viscous potential flow theory has been used for the investigation. Both fluids are taken as incompressible, viscous and dielectric with different kinematic viscosities and different permittivities. In the viscous potential flow theory, viscosity enters through normal stress …balance and effect of shearing stresses is completely neglected. We include the viscous pressure in the normal stress balance along with irrotational pressure and it is assumed that this viscous pressure will resolve the discontinuity of the tangential stresses at the interface of two fluids. A dispersion relation has been derived and stability is discussed theoretically as well as numerically. Stability criterion is given in terms of a critical value of relative velocity of two fluids as well as critical value of the applied electric field. It has been observed that tangential electric field and vapor fraction both have stabilizing effect on the stability of the system while heat and mass transfer destabilizes the interface. Also, it has been found that the effect of irrotational shearing stresses stabilizes the system. Show more

Keywords: Viscous correction, viscous potential flow, Kelvin-Helmholtz stability, incompressible fluid, viscous pressure, tangential electric field

DOI: 10.3233/JAE-131664

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 2, pp. 283-301, 2013

Authors: Izadi, M. | Ab Kadir, M.Z.A. | Hajikhani, M.

Article Type: Research Article

Abstract: In this paper a general set of field expressions associated with a lightning channel are proposed to evaluate the electromagnetic fields due to lightning in the presence of a ground reflection at the channel base. The ground reflection factor is due to the difference between the channel and ground impedances and can enter additional reflected currents into the lightning channel. The proposed field expressions can support the widely used current functions and current models directly in …the time domain without the need to apply any extra conversions. Moreover, the proposed expressions are applied on a sample of lightning current that has been obtained from a triggered lightning experiment and the evaluated electromagnetic fields are compared to the corresponding measured fields and the results discussed accordingly. The results illustrate that the simulated fields based on the proposed method are in good agreement with the measured fields. Moreover, the ground reflection factor can have a great effect on the values of the lightning electromagnetic fields. The proposed field expressions consider all field components directly in the time domain and vary appropriately to join with widely used coupling models to evaluate the lightning induced voltage on power lines without the need to apply any extra conversions. Show more

Keywords: Lightning, electromagnetic fields, ground reflection factor

DOI: 10.3233/JAE-131665

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 2, pp. 303-317, 2013

Authors: Zhou, Deqiang | Li, Yong | Yan, Xiangyang | You, Lihua | Zhang, Qiuju | Liu, Xiangbiao | Qi, Yong

Article Type: Research Article

Abstract: Pulsed Eddy Current Testing (PECT) is one of the advanced Electromagnetic Nondestructive Evaluation (ENDE) technology. In applications for crack detection and evaluation, rectangular probes are found superior to the cylindrical ones in terms of the directional characteristics and capability of creating uniform eddy current distributions. In this paper, in a bid to investigate the influence of parameters of a rectangular probe on inspection sensitivity and seek the optimal probe structure, a numerical model for …conductivity/defect assessment with a rectangular probe is built up by using Comsol. Following this, experiments on flaw evaluation are undertaken by using the probe with the optimal parameters found in Finite Element Modelling (FEM). Through simulations and experiments, it can be seen that the rectangular probe with dimensions in the proportion of 2:1:1.5 (length:width:height) is optimal for conductivity evaluation. Show more

Keywords: Electromagnetic nondestructive evaluation, pulsed eddy current, rectangular probe, conductivity, defect detection and evaluation, finite element simulation

DOI: 10.3233/JAE-131681

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 2, pp. 319-326, 2013