某型教练机机翼整体油箱上壁板腐蚀原因分析和防腐处理措施

介绍了某型教练机多架机翼整体油箱上壁板在特定位置先后发现的不同程度的腐蚀情况,通过分析当地使用环境和结构特点,找出了壁板发生腐蚀的原因,结合飞机在当地的实际使用环境编制了加速腐蚀试验谱,并设计模拟件进行了加速腐蚀试验验证,确定了防腐处理措施.     

先进上面级变轨段姿态解耦控制研究

针对多星部署先进上面级变轨段三轴姿态严重耦合以及主发动机开机引起的较大干扰力矩问题,研究了基于反馈线性化的姿态解耦算法。通过给出上面级多星部署任务中的坐标系和姿态角定义,建立了欧拉角描述的姿态动力学与运动学方程。分析了推力矢量与姿控发动机的控制方案,描述了该方案中主发动机、伺服机构和姿控发动机的配置结构,推导了推力矢量控制中的主发动机摆角计算公式和主发动机工作时质心偏移引起的干扰力矩。基于反馈线性化理论,设计了上面级姿态解耦控制律。算例验证结果表明姿态角速率误差和姿态角误差能够快速趋于1°/s和0.5°。文中设计的姿态解耦控制算法具有良好的稳定性和可行性。     

A model of foreground emission in UV using GALEX deep observations

Foreground emission, mainly airglow and zodiacal light, is a significant contributor in an ultraviolet observation especially from low earth orbit. Its careful estimation and removal are tedious yet unavoidable processes in the study of diffuse UV radiation and by extension interstellar dust studies. Our analysis of deep GALEX observations show that airglow is not only a function of Sun angle but also a strong function of Solar activity at the time of observation. We present here an empirical model of airglow emission, derived from GALEX deep observations, as a function of 10.7 cm Solar flux and Sun angle. We obtained the model by training machine learning models on the data using a variant of the regression algorithm that is both resilient toward outlier data and sensitive to the complexities of the provided data. Our model predictions across various observations show no loss in generalization as well as good agreement with the observed values. We find that the total airglow in an observation is the sum of a baseline part (AG_c) that depends on the Solar flux and Sun angle, and a variable part (AG_v) that depends on the Sun angle and the time of observation with respect to local midnight. We also find that the total airglow can vary between 85 – 390 photon units in FUV and 80 – 465 photon units in NUV.