When a pico satellite is under normal operational condi- tions, whether it is extended or unscented, a conventional Kalman filter gives sufficiently good estimation results. However, if the measurements are not reliab...When a pico satellite is under normal operational condi- tions, whether it is extended or unscented, a conventional Kalman filter gives sufficiently good estimation results. However, if the measurements are not reliable because of any kind of malfunc- tions in the estimation system, the Kalman filter gives inaccurate results and diverges by time. This study compares two different robust Kalman filtering algorithms, robust extended Kalman filter （REKF） and robust unscented Kalman filter （RUKF）, for the case of measurement malfunctions. In both filters, by the use of de- fined variables named as the measurement noise scale factor, the faulty measurements are taken into the consideration with a small weight, and the estimations are corrected without affecting the characteristic of the accurate ones. The proposed robust Kalman filters are applied for the attitude estimation process of a pico satel- lite, and the results are compared.展开更多
We report a high repetition frequency, high power stability and low laser noise laser-diode(LD) end-pumped Nd: YAG ceramic passively Q-switched laser at 1123 nm based on a Ti_(3)C_(2)T_(x)-polyvinyl alcohol(PVA) film ...We report a high repetition frequency, high power stability and low laser noise laser-diode(LD) end-pumped Nd: YAG ceramic passively Q-switched laser at 1123 nm based on a Ti_(3)C_(2)T_(x)-polyvinyl alcohol(PVA) film as a saturable absorber(SA). A Brewster polarizer(BP) and a birefringent crystal(BC) are incorporated to enable frequency selection and filtering for the passively Q-switched 1123 nm pulsed laser to improve the power stability and reduce the noise. When the pump power is 5.1 W, an average output power of 457.9 m W is obtained, corresponding to a repetition frequency of 1.09 MHz,a pulse width of 56 ns, a spectral line width of 0.65 nm, a power instability of ±0.92%, and a laser noise of 0.89%.The successful implementation of the “Ti_(3)C_(2)T_(x)-PVA film passively Q-switching” combined with “frequency selection and filtering of BP + BC” technology path provides a valuable reference for developing pulsed laser with high repetition frequency, high stability and low noise.展开更多
目的对V型滤池的设计进行标准化处理,研发V型滤池参数化设计与绘图系统.方法以《室外给水设计规范》(GB50013—2006)为依据,Auto CAD为二次开发平台,利用其内嵌的VBA语言、可视化接口和Active X Automation技术,选用滤速为设计控制参数...目的对V型滤池的设计进行标准化处理,研发V型滤池参数化设计与绘图系统.方法以《室外给水设计规范》(GB50013—2006)为依据,Auto CAD为二次开发平台,利用其内嵌的VBA语言、可视化接口和Active X Automation技术,选用滤速为设计控制参数,反冲洗强度、反冲洗周期、反冲洗时间等为辅助设计参数,建立V型滤池计算模型和参数化绘图模块.结果创建多个绘图点计算定位和参数化绘图的基本函数;系统自动完成滤池主体,水反冲洗、气反冲洗和气水联合反冲洗系统设计;确定V型滤池各部分的尺寸,并按规范对计算结果自动进行校核.结论利用所建模型和基本函数直接调用计算结果,完成V型滤池参数化绘图工作,自动生成CAD图形.展开更多
文摘When a pico satellite is under normal operational condi- tions, whether it is extended or unscented, a conventional Kalman filter gives sufficiently good estimation results. However, if the measurements are not reliable because of any kind of malfunc- tions in the estimation system, the Kalman filter gives inaccurate results and diverges by time. This study compares two different robust Kalman filtering algorithms, robust extended Kalman filter （REKF） and robust unscented Kalman filter （RUKF）, for the case of measurement malfunctions. In both filters, by the use of de- fined variables named as the measurement noise scale factor, the faulty measurements are taken into the consideration with a small weight, and the estimations are corrected without affecting the characteristic of the accurate ones. The proposed robust Kalman filters are applied for the attitude estimation process of a pico satel- lite, and the results are compared.
基金Project supported by the Serving Local Special Project of Shaanxi Provincial Department of Education of China (Grant No. 19JC040)the National Natural Science Foundation of China (Grant No. 61905193)。
文摘We report a high repetition frequency, high power stability and low laser noise laser-diode(LD) end-pumped Nd: YAG ceramic passively Q-switched laser at 1123 nm based on a Ti_(3)C_(2)T_(x)-polyvinyl alcohol(PVA) film as a saturable absorber(SA). A Brewster polarizer(BP) and a birefringent crystal(BC) are incorporated to enable frequency selection and filtering for the passively Q-switched 1123 nm pulsed laser to improve the power stability and reduce the noise. When the pump power is 5.1 W, an average output power of 457.9 m W is obtained, corresponding to a repetition frequency of 1.09 MHz,a pulse width of 56 ns, a spectral line width of 0.65 nm, a power instability of ±0.92%, and a laser noise of 0.89%.The successful implementation of the “Ti_(3)C_(2)T_(x)-PVA film passively Q-switching” combined with “frequency selection and filtering of BP + BC” technology path provides a valuable reference for developing pulsed laser with high repetition frequency, high stability and low noise.
文摘目的对V型滤池的设计进行标准化处理,研发V型滤池参数化设计与绘图系统.方法以《室外给水设计规范》(GB50013—2006)为依据,Auto CAD为二次开发平台,利用其内嵌的VBA语言、可视化接口和Active X Automation技术,选用滤速为设计控制参数,反冲洗强度、反冲洗周期、反冲洗时间等为辅助设计参数,建立V型滤池计算模型和参数化绘图模块.结果创建多个绘图点计算定位和参数化绘图的基本函数;系统自动完成滤池主体,水反冲洗、气反冲洗和气水联合反冲洗系统设计;确定V型滤池各部分的尺寸,并按规范对计算结果自动进行校核.结论利用所建模型和基本函数直接调用计算结果,完成V型滤池参数化绘图工作,自动生成CAD图形.
