A new type fully reversible combined blade is presented, which can fully reverse airflow during the inverse ventilation by simply reversion. It is suitable for reversible axial flow fans used in tunnel and mine ventil...A new type fully reversible combined blade is presented, which can fully reverse airflow during the inverse ventilation by simply reversion. It is suitable for reversible axial flow fans used in tunnel and mine ventilation. The optimal parameters such as overlap ratio and pitch ratio are determined through cascade experiment. Experiment results also show a big promotion of maximum lift coefficient C1,max and stall attack angle a1,max compared to the existing bi-directional symmetry airfoils.展开更多
Microelectromechanical systems(MEMS)gyroscopes with higher precision have always been a focal point of research.Due to limitations in resonant structure,fabrication processes,and measurement and control techniques,MEM...Microelectromechanical systems(MEMS)gyroscopes with higher precision have always been a focal point of research.Due to limitations in resonant structure,fabrication processes,and measurement and control techniques,MEMS gyroscopes with bias instability better than 0.01°/h are still rare and expensive.This paper incorporates electrode machining error and capacitance detection nonlinear error into the gyroscope model,resulting in a more comprehensive bias output model.Based on this,a mode reversal combined mode deflection control method is proposed to eliminate the thermal drift and decrease the bias instability of the gyroscope.Experimental results demonstrate that compared with the traditional force-to-rebalance mode,the new method achieves a 595 times reduction in bias variation during−40℃ to+60℃ temperature cycles and a 6.3 times reduction in bias instability at room temperature.The average bias instability of honeycomb disk resonator gyroscopes can reach 0.003°/h at integration times of 8500 s after applying the new method across three prototypes,which is the best reported performance of the MEMS gyroscope thus far.This paper provides a new paradigm for achieving higher precision MEMS gyroscopes.展开更多
文摘A new type fully reversible combined blade is presented, which can fully reverse airflow during the inverse ventilation by simply reversion. It is suitable for reversible axial flow fans used in tunnel and mine ventilation. The optimal parameters such as overlap ratio and pitch ratio are determined through cascade experiment. Experiment results also show a big promotion of maximum lift coefficient C1,max and stall attack angle a1,max compared to the existing bi-directional symmetry airfoils.
基金supported by the National Key Research and Development Program of China under grant no.2022YFB3207301in part by the National Natural Science Foundation of China under grant 62304255 and grant U21A20505。
文摘Microelectromechanical systems(MEMS)gyroscopes with higher precision have always been a focal point of research.Due to limitations in resonant structure,fabrication processes,and measurement and control techniques,MEMS gyroscopes with bias instability better than 0.01°/h are still rare and expensive.This paper incorporates electrode machining error and capacitance detection nonlinear error into the gyroscope model,resulting in a more comprehensive bias output model.Based on this,a mode reversal combined mode deflection control method is proposed to eliminate the thermal drift and decrease the bias instability of the gyroscope.Experimental results demonstrate that compared with the traditional force-to-rebalance mode,the new method achieves a 595 times reduction in bias variation during−40℃ to+60℃ temperature cycles and a 6.3 times reduction in bias instability at room temperature.The average bias instability of honeycomb disk resonator gyroscopes can reach 0.003°/h at integration times of 8500 s after applying the new method across three prototypes,which is the best reported performance of the MEMS gyroscope thus far.This paper provides a new paradigm for achieving higher precision MEMS gyroscopes.
