Papers by Author: Qin Shi

Abstract: Ni-P-multi-walled carbon nanotubes (Ni-P-MWNTs) composite coating was successfully co-deposited on 45 steel substrate by electroless plating. The microscopic morphology of Ni-P-MWNTs composite coating was observed by SEM. The influences of CNTs concentration in plating bath on the microstructure and corrosion resistance of the composite coating were investigated. The results indicated that the deposited composite coating shows dispersed CNTs and continuous Ni-P matrix, and there are no pores and cracks and other defects at the interface between the substrate and composite coating, and the thickness of the composite coating is about 50 μm. The Ni-P-MWNTs composite coating with 0.3g/L CNTs in bath displayed the best corrosion resistance, the corrosion potential of the composite coating is-0.372V.

Abstract: The principle of drive closed-loop for tuning fork comb MEMS vibratory gyroscope is analyzed. The core of the closed-loop is to keep the vibration speed stable by adding driving force offset the damping force. The closed-loop with a single Automatic Gain Control (AGC) loop is chosen to maintain the vibration speed stable, and then the closed-loop with AGC is analyzed to obtain its transfer function. The transfer function simplifies the nonlinear AGC system to a linear system which is easy analyzed its parameters impacting the system. The values of two important parameters of AGC were chosen via simulation. The whole closed-loop system was simulated in SIMULINK. The circuit is built and tested in accordance with the theory of analysis and simulation. Experimental results demonstrate that the stability of the amplitude of vibration speed is 90ppm; and that of the frequency of vibration speed is 114ppm.

Abstract: The performance of silicon micro gyroscope affected by the quality factor of silicon micro gyroscope is introduced. The temperature characteristics of quality factor of silicon micro gyroscope are also presented. The theoretical analysis suggests that the air damping is the key factor determining the quality factor of silicon micro gyroscope and the quality factor determined by the air damping is in inverse proportion to the square root of temperature. According to the theory, the reciprocal of the quality factor of gyroscope can be approximately expressed as a linear equation with respect to temperature over a temperature range from 238K to 328K. Using the high speed data acquisition card to sample the decayed drive amplitude signal of gyroscope, the quality factor of gyroscope can be calculated from those sample data. The quality factors of gyroscopes at different temperature are experimented in a high accurate thermostat. The experimental results validate the approximate relationship between the quality factor of silicon micro gyroscope and the temperature.