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.     

国外典型核武器内部氢气气氛分析

核武器密闭空间内部气氛中的氢气对铀材料、钚材料可靠性有长期的影响,将会引起严重的腐蚀失效,导致武器装备战技指标下降,同时也给核武器本身的安全性也带来了隐患。以基于理论模型的假想核武器为研究对象,经分析表明,核武器内部氢气主要来源于铀材料与外界渗漏气体的反应,以及有机材料的老化,这些气体在热应力条件下扩散到核武器密闭空间内部。国外有核国家目前主要采用研制生产时改进加工工艺,控制初始状态;交付后,在核武器内部放置干燥剂、吸氢剂2种措施相结合的方法控制核武器内部的氢气浓度,这些做法对我国武器装备的发展都有一定的借鉴意义。