Gives a dynamic mathematical model of a typical type of multiple discs hydroviscous drive device which has been proved to be correct through tests.Utilizing the method of root-locus analysis the dynamic performance of...Gives a dynamic mathematical model of a typical type of multiple discs hydroviscous drive device which has been proved to be correct through tests.Utilizing the method of root-locus analysis the dynamic performance of this device is studied according to the model.Theoretical analysis and test re- suits show that the dynamic performance of the object of study can be greatly improved by speed negative feedback.展开更多
This paper investigates the effects of material and dimension parameters on the frequency splitting,frequency drift,and quality factor(Q)of aluminium nitride(AlN)-on-n-doped/pure silicon(Si)microelectromechanical syst...This paper investigates the effects of material and dimension parameters on the frequency splitting,frequency drift,and quality factor(Q)of aluminium nitride(AlN)-on-n-doped/pure silicon(Si)microelectromechanical systems(MEMS)disk resonators through analysis and simulation.These parameters include the crystallographic orientation,dopant,substrate thickness,and temperature.The resonators operate in the elliptical,higher order,and flexural modes.The simulation results show that i)the turnover points of the resonators exist at 55°C,-50°C,40°C,and-10°C for n-doped silicon with the doping concentration of 2×1019 cm-3 and the Si thickness of 3.5μm,and these points are shifted with the substrate thickness and mode variations;ii)compared with pure Si,the modal-frequency splitting for n-doped Si is higher and increases from 5%to 10%for all studied modes;iii)Q of the resonators depends on the temperature and dopant.Therefore,the turnover,modal-frequency splitting,and Q of the resonators depend on the thickness and material of the substrate and the temperature.This work offers an analysis and design platform for high-performance MEMS gyroscopes as well as oscillators in terms of the temperature compensation by n-doped Si.展开更多
我国全膜高压并联补偿电容器经过20年的普及使用,不论是生产厂家还是用户均有人提出:当年由全国无功补偿装置专家工作组确定的全膜电容器设计场强不宜大于57 k V/mm(k=1)的指标不适用了,应提高电容器设计场强。经对我国主导生产厂家的...我国全膜高压并联补偿电容器经过20年的普及使用,不论是生产厂家还是用户均有人提出:当年由全国无功补偿装置专家工作组确定的全膜电容器设计场强不宜大于57 k V/mm(k=1)的指标不适用了,应提高电容器设计场强。经对我国主导生产厂家的三膜结构并联电容器绝缘耐受水平的研究,得出专家工作组的这一规定对我国全膜高压并联电容器健康快速发展起到了十分关键的作用,进一步提高设计场强应谨慎,应在进行充分研究的基础上再做提高设计场强变更,否则对产品的运行可靠性是不利的。展开更多
文摘Gives a dynamic mathematical model of a typical type of multiple discs hydroviscous drive device which has been proved to be correct through tests.Utilizing the method of root-locus analysis the dynamic performance of this device is studied according to the model.Theoretical analysis and test re- suits show that the dynamic performance of the object of study can be greatly improved by speed negative feedback.
文摘This paper investigates the effects of material and dimension parameters on the frequency splitting,frequency drift,and quality factor(Q)of aluminium nitride(AlN)-on-n-doped/pure silicon(Si)microelectromechanical systems(MEMS)disk resonators through analysis and simulation.These parameters include the crystallographic orientation,dopant,substrate thickness,and temperature.The resonators operate in the elliptical,higher order,and flexural modes.The simulation results show that i)the turnover points of the resonators exist at 55°C,-50°C,40°C,and-10°C for n-doped silicon with the doping concentration of 2×1019 cm-3 and the Si thickness of 3.5μm,and these points are shifted with the substrate thickness and mode variations;ii)compared with pure Si,the modal-frequency splitting for n-doped Si is higher and increases from 5%to 10%for all studied modes;iii)Q of the resonators depends on the temperature and dopant.Therefore,the turnover,modal-frequency splitting,and Q of the resonators depend on the thickness and material of the substrate and the temperature.This work offers an analysis and design platform for high-performance MEMS gyroscopes as well as oscillators in terms of the temperature compensation by n-doped Si.
文摘我国全膜高压并联补偿电容器经过20年的普及使用,不论是生产厂家还是用户均有人提出:当年由全国无功补偿装置专家工作组确定的全膜电容器设计场强不宜大于57 k V/mm(k=1)的指标不适用了,应提高电容器设计场强。经对我国主导生产厂家的三膜结构并联电容器绝缘耐受水平的研究,得出专家工作组的这一规定对我国全膜高压并联电容器健康快速发展起到了十分关键的作用,进一步提高设计场强应谨慎,应在进行充分研究的基础上再做提高设计场强变更,否则对产品的运行可靠性是不利的。
