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Zhu Junchao,Wei Guangcheng,Peng Zilong,Xia Zhaowang,Zheng Liangyan,Zhu Hanhua 대한조선학회 2022 International Journal of Naval Architecture and Oc Vol.14 No.1
Warship always face the threat of underwater explosion shock, which may affect the ship stern tube bearing lubrication performance when the propeller shaft is bending. This paper builds the coupling model of shaft longitudinal vibration and bearing lubrication with consideration of shaft axial shock and misalignment. The performance of stern bearing under the influence of explosion shock was analyzed by solving the generalized Reynolds equation, shaft longitudinal vibration equation and explosion shock equation. The result shows that: the effect of underwater explosion shock on bearing lubrication performance is transient, and the effect will be more obvious when the bearing works at close quarter, larger misaligned angle, eccentricity and rotation speed. Moreover, the edge effect which caused by shaft bending will increase with the decrease of explosion distance and the increase of eccentricity.
Lianxi Liu,Junchao Mu,Wenzhi Yuan,Wei Tu,Zhangming Zhu,Yintang Yang 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.3
For wearable health monitoring systems, a fundamental problem is the limited space for storing energy, which can be translated into a short operational life. In this paper, a highly efficient active voltage doubling rectifier with a wide input range for micro-piezoelectric energy harvesting systems is proposed. To obtain a higher output voltage, the Dickson charge pump topology is chosen in this design. By replacing the passive diodes with unbalanced-biased comparator-controlled active counterparts, the proposed rectifier minimizes the voltage losses along the conduction path and solves the reverse leakage problem caused by conventional comparator-controlled active diodes. To improve the rectifier input voltage sensitivity and decrease the minimum operational input voltage, two low power common-gate comparators are introduced in the proposed design. To keep the comparator from oscillating, a positive feedback loop formed by the capacitor C is added to it. Based on the SMIC 0.18-μm standard CMOS process, the proposed rectifier is simulated and implemented. The area of the whole chip is 0.91×0.97 ㎟, while the rectifier core occupies only 13% of this area. The measured results show that the proposed rectifier can operate properly with input amplitudes ranging from 0.2 to 1.0V and with frequencies ranging from 20 to 3000 Hz. The proposed rectifier can achieve a 92.5% power conversion efficiency (PCE) with input amplitudes equal to 0.6 V at 200 Hz. The voltage conversion efficiency (VCE) is around 93% for input amplitudes greater than 0.3 V and load resistances larger than 20kΩ.
Liu, Lianxi,Mu, Junchao,Yuan, Wenzhi,Tu, Wei,Zhu, Zhangming,Yang, Yintang The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.3
For wearable health monitoring systems, a fundamental problem is the limited space for storing energy, which can be translated into a short operational life. In this paper, a highly efficient active voltage doubling rectifier with a wide input range for micro-piezoelectric energy harvesting systems is proposed. To obtain a higher output voltage, the Dickson charge pump topology is chosen in this design. By replacing the passive diodes with unbalanced-biased comparator-controlled active counterparts, the proposed rectifier minimizes the voltage losses along the conduction path and solves the reverse leakage problem caused by conventional comparator-controlled active diodes. To improve the rectifier input voltage sensitivity and decrease the minimum operational input voltage, two low power common-gate comparators are introduced in the proposed design. To keep the comparator from oscillating, a positive feedback loop formed by the capacitor C is added to it. Based on the SMIC 0.18-μm standard CMOS process, the proposed rectifier is simulated and implemented. The area of the whole chip is 0.91×0.97 mm<sup>2</sup>, while the rectifier core occupies only 13% of this area. The measured results show that the proposed rectifier can operate properly with input amplitudes ranging from 0.2 to 1.0V and with frequencies ranging from 20 to 3000 Hz. The proposed rectifier can achieve a 92.5% power conversion efficiency (PCE) with input amplitudes equal to 0.6 V at 200 Hz. The voltage conversion efficiency (VCE) is around 93% for input amplitudes greater than 0.3 V and load resistances larger than 20kΩ.