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Clearance Measurement Equipment for Gas Lubricated Dynamic Pressure Bearing of Gyro Motor
Tong-qun Ren,Zhi-rou Liu,Xiang-dong Xu,Yu Liu,Xiaodong Wang 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.12
The clearance of gas lubricated dynamic pressure bearing of gyro motor refers specifically to small internal air gap between the rotor and stator. The clearance size is an important indicator of running performance of a motor. In this work, a dedicated clearance measurement equipment is developed. The clearance is converted to external micro displacement and measured by dual inductive probes with relative measurement principle. For this purpose, three main functional modules are designed together with corresponding electronic and pneumatic control systems. The clamp fixation module helps to support the measured bearing flexibly at the shaft end, which is conducive to protect the bearing and ensure the smoothness of force application. The force application module consists of a 3-D precision motion platform and a triaxial force sensor. It converts internal air gap to external micro displacement in cooperation with the clamp fixation module. The displacement measurement module is a 2-D precision motion platform carrying dual inductive probes. Based on theoretical analysis and practical experiments, the measurement accuracy is superior to 0.3 μm. Moreover, it realizes controllable and continuous force application, which is suitable for batch measurement.
Asymmetrical Pulse-Width-Modulated Full-Bridge Secondary Dual Resonance DC–DC Converter
Zhangyong Chen,Qun Zhou,Jianping Xu,Xiang Zhou 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.6
A full-bridge secondary dual-resonant DC?DC converter using the asymmetrical pulse-width modulated (APWM) strategy is proposed in this paper. The proposed converter achieves zero-voltage switching for the power switches and zero-current switching for the rectifier diodes in the whole load range without the help of any auxiliary circuit. Given the use of the APWM strategy, a circulating current that exists in a traditional phase-shift full-bridge converter is eliminated. The voltage stress of secondary rectifier diodes in the proposed converter is also clamped to the output voltage. Thus, the existing voltage oscillation of diodes in traditional PSFB converters is eliminated. This paper presents the circuit configuration of the proposed converter and analyzes its operating principle. Experimental results of a 1 kW 385 V/48 V prototype are presented to verify the analysis results of the proposed converter.
FDU-12 Mesoporous Materials Detection Hg (Ⅱ) Ions by QCM
Huihui Lou,Chong Shen,Qun Xiang,Jiaqiang Xu,Tianjun Lou 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.8
Thiol-functionalized three-dimensional (3D) mesoporous silica FDU-12 and SBA-15 with ordered pore were prepared. All the obtained materials were characterized by small angle X-ray scattering (SAXS), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Mesoporous silica FDU-12 (Fm3m) materials with various unit cell sizes, multifaceted pore were convenient for the interaction of subject and object; the 2D SBA-15 mesoporous silica materials with short and order pore channel were better than the traditional SBA-15 mesoporous silica, in which the pore channel can be used fully. 3D mesoporous silica FDU-12 is used as a sensing material to reconstruct QCM sensors to enhance the stability and this material is an ideal material to deal with heavy metal ions in water.
SIMULATION AND OPTIMIZATION METHODS OF THE THERMAL CONTROL LOOP OF SPACECRAFT
Xin Gang Liang,Qun Chen,Xiang Hua Xu 대한기계학회 2019 대한기계학회 춘추학술대회 Vol.2019 No.5
Power consumption keeps increasing with increase in their functions and capabilities of spacecraft, which in turn results in the requirement of thermal control techniques, efficient that dissipation and thermal management. The numerical simulation of the thermal control loop should be performed before and after its design and ground test of the thermal control and management is necessary to measure their reliability. A semi-physical ground test method for the thermal control loop of space station is proposed which can realize dynamic measurement of the thermal control loop. A method of simplifying the numerical simulation of the thermal control loop is developed and a new technique, the heat flow circuit, is induced for the numerical simulation and optimization of the thermal control loop.
Asymmetrical Pulse-Width-Modulated Full-Bridge Secondary Dual Resonance DC-DC Converter
Chen, Zhangyong,Zhou, Qun,Xu, Jianping,Zhou, Xiang The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.6
A full-bridge secondary dual-resonant DC-DC converter using the asymmetrical pulse-width modulated (APWM) strategy is proposed in this paper. The proposed converter achieves zero-voltage switching for the power switches and zero-current switching for the rectifier diodes in the whole load range without the help of any auxiliary circuit. Given the use of the APWM strategy, a circulating current that exists in a traditional phase-shift full-bridge converter is eliminated. The voltage stress of secondary rectifier diodes in the proposed converter is also clamped to the output voltage. Thus, the existing voltage oscillation of diodes in traditional PSFB converters is eliminated. This paper presents the circuit configuration of the proposed converter and analyzes its operating principle. Experimental results of a 1 kW 385 V/48 V prototype are presented to verify the analysis results of the proposed converter.
Yue Li,Jing-Ying Zhang,Xin-Yue Zhao,Li-Ya Pan,De-Hao Jin,He-Xing Xu,Hu-Zhe Cui,Yan-Qun Liu,Xiang-Zheng Qin,Qingyuan Li 대한정형외과학회 2021 Clinics in Orthopedic Surgery Vol.13 No.2
Background: The accessory tendon of the extensor hallucis longus (ATEHL) muscle is a common abnormal structure, and its clinical significance remains debatable. In this study, we provide the incidence of the ATEHL and characterize its morphological types in Asian cadavers and investigate its clinical applications. Methods: The tendons from 50 adult cadaveric feet, fixed in 10% formalin, were analyzed. We measured the length and width of both the ATEHL and the extensor hallucis brevis (EHB). Results: All dissected specimens had an ATEHL. The first metatarsophalangeal joint was surrounded by an accessory tendon that inserted onto the joint capsule and the dorsal base of the proximal phalanx. We classified the ATEHL into 3 types based on their directions. Differences in ATEHL type based on sex were not statistically significant. Conclusions: We found an ATEHL in all cadaveric specimens in this study. We surmise that the ATEHL acts as an antagonist with the EHB when the toe is extending, which might help prevent the occurrence of hallux valgus deformity.