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Hosein Ataei,Yaghoub Tadi Beni,Milad Shojaeian 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.4
Pull-in instability and free vibration of cantilever and clamped-clamped beam-type nanoactuators, which are made of Functionally graded materials (FGMs), are investigated using the Modified strain gradient theory (MSGT) under the influence of electrostatic and intermolecular forces. It is assumed that the functionally graded nano-beam made of nickel and silicon nitride and mechanical properties of the nano-beam vary continuously and smoothly in the thickness direction by a simple power-law distribution. Differential quadrature method (DQM), Differential transformation method_Pade approximant (DTM_Pade) and Lumped parameter model (LPM) are used to solve the nonlinear governing equation of the nano-beam, and the obtained results from these methods are compared together. In the end, the effects of size, variation of the length scale parameter, and the volume fraction are discussed and examined. The results show that there are a good agreement between the MSGT and the experimental results, so it can be conclude that the size effect has a substantial impact on the pull-in instability and free vibration results of the beam-type micro/nanoactuator.
Rahmat-Allah Hooshmand,Mohammad Ataei,Mohammad Hosein Rezaei 전력전자학회 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.1
These days, the application of electronic power transformers (EPTs) is expanding in place of ordinary power transformers. These transformers can transmit power via three or four wire converters. Their dynamic performance is extremely important, due to their complex structure. In this paper, a new method is proposed for improving the dynamic performance of distribution electronic power transformers (DEPT) by using sliding mode control (SMC). Hence, to express the dynamic characteristics of a system, different factors such as the voltage unbalance, voltage sag, voltage harmonics and voltage flicker in the system primary side are considered. The four controlling aims of the improvement in dynamic performance include: 1) maintaining the input currents so that they are in sinusoidal form and in phase with the input voltages so they have a unity power factor, 2) keeping the dc-link voltage within the reference amount, 3) keeping the output voltages at a fixed amount and 4) keeping the output voltages in sinusoidal and symmetrical forms. Simulation results indicate the potential and capability of the proposed method in improving DEPT behavior.
Hooshmand, Rahmat-Allah,Ataei, Mohammad,Rezaei, Mohammad Hosein The Korean Institute of Power Electronics 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.1
These days, the application of electronic power transformers (EPTs) is expanding in place of ordinary power transformers. These transformers can transmit power via three or four wire converters. Their dynamic performance is extremely important, due to their complex structure. In this paper, a new method is proposed for improving the dynamic performance of distribution electronic power transformers (DEPT) by using sliding mode control (SMC). Hence, to express the dynamic characteristics of a system, different factors such as the voltage unbalance, voltage sag, voltage harmonics and voltage flicker in the system primary side are considered. The four controlling aims of the improvement in dynamic performance include: 1) maintaining the input currents so that they are in sinusoidal form and in phase with the input voltages so they have a unity power factor, 2) keeping the dc-link voltage within the reference amount, 3) keeping the output voltages at a fixed amount and 4) keeping the output voltages in sinusoidal and symmetrical forms. Simulation results indicate the potential and capability of the proposed method in improving DEPT behavior.