Aiming at a kind of middle ear implant（MEI）, the driving voltage of a piezoelectric floating mass actuator is analyzed using a 0. 7Pb （Mg1/3Nb2/3） O3-0. 3PbTiO3 （ PMN- 30% PT）stack as a new type of vibrator. For...Aiming at a kind of middle ear implant（MEI）, the driving voltage of a piezoelectric floating mass actuator is analyzed using a 0. 7Pb （Mg1/3Nb2/3） O3-0. 3PbTiO3 （ PMN- 30% PT）stack as a new type of vibrator. For the purpose of facilitating the analysis, a simplified coupling model of the ossicular chain and the piezoelectric actuator is constructed. First, a finite element model of a human middle ear is constructed by reverse engineering technology, and the validity of this model is confirmed by comparing the simulated motion of the stapes footplate obtained by this model with experimental measurements. Then the displacement impedance of the incus long process is analyzed, and a single mass-spring-damper equivalent model of the ossicular chain attached with the clamp is derived. Finally, a simplified coupling model of the ossicular chain and the piezoelectric actuator is established and used to analyze the driving voltage property of the actuator. The results show that the required driving voltage decreases with the increase in the frequency, and the maximum required driving voltage is 20. 9 V in the voice frequencies. However, in the mid-high frequencies where most sensorineural hearing loss occurs, the maximum required driving voltage is 3.8 V, which meets the low-voltage and low-power requirements of the MEI.展开更多
In the period 2003-2011, lightning over-voltages accounted for about 47% of the total number of distribution transformer failures observed in the service area ofAES Sul, a power company that operates in the state of R...In the period 2003-2011, lightning over-voltages accounted for about 47% of the total number of distribution transformer failures observed in the service area ofAES Sul, a power company that operates in the state of Rio Grande doSul, in South Brazil. This paper presents the results of an investigation on the influence of the distance between transformer and MV arresters on the surges at the transformer windings caused by direct strikes to the MV network. The analysis, performed through simulations using the Alternative Transients Program, shows that in general higher voltages are produced by subsequent strokes. Although in relation to the primary side the surges transferred to the secondary are much less affected by the distance between transformers and primary arresters, such distance should always be kept as short as possible in order to reduce the probability of occurrence of transformer failures due to over-voltages at the MV bushings.展开更多
基金The National Natural Science Foundation of China(No10772121)the Med-Science Cross Research Foundation of Shanghai Jiao-tong University (NoYG2007MS14)
文摘Aiming at a kind of middle ear implant（MEI）, the driving voltage of a piezoelectric floating mass actuator is analyzed using a 0. 7Pb （Mg1/3Nb2/3） O3-0. 3PbTiO3 （ PMN- 30% PT）stack as a new type of vibrator. For the purpose of facilitating the analysis, a simplified coupling model of the ossicular chain and the piezoelectric actuator is constructed. First, a finite element model of a human middle ear is constructed by reverse engineering technology, and the validity of this model is confirmed by comparing the simulated motion of the stapes footplate obtained by this model with experimental measurements. Then the displacement impedance of the incus long process is analyzed, and a single mass-spring-damper equivalent model of the ossicular chain attached with the clamp is derived. Finally, a simplified coupling model of the ossicular chain and the piezoelectric actuator is established and used to analyze the driving voltage property of the actuator. The results show that the required driving voltage decreases with the increase in the frequency, and the maximum required driving voltage is 20. 9 V in the voice frequencies. However, in the mid-high frequencies where most sensorineural hearing loss occurs, the maximum required driving voltage is 3.8 V, which meets the low-voltage and low-power requirements of the MEI.
文摘In the period 2003-2011, lightning over-voltages accounted for about 47% of the total number of distribution transformer failures observed in the service area ofAES Sul, a power company that operates in the state of Rio Grande doSul, in South Brazil. This paper presents the results of an investigation on the influence of the distance between transformer and MV arresters on the surges at the transformer windings caused by direct strikes to the MV network. The analysis, performed through simulations using the Alternative Transients Program, shows that in general higher voltages are produced by subsequent strokes. Although in relation to the primary side the surges transferred to the secondary are much less affected by the distance between transformers and primary arresters, such distance should always be kept as short as possible in order to reduce the probability of occurrence of transformer failures due to over-voltages at the MV bushings.
