三轴稳定地球同步轨道卫星帆板季节性闪光现象研究

季节性闪光现象是由三轴稳定地球同步轨道(GEO)卫星保持的特殊对地位置及卫星帆板的运动特点产生的。结合卫星帆板材质的双向反射分布函数及太阳在地球坐标系下的运动规律,分析了帆板季节性闪光现象的原理,定量研究了地面站观测帆板闪光现象的相关规律并进行了仿真验证。研究表明,地面任意地点的望远镜每年都有两个时段能够观测到GEO卫星帆板闪光现象,每次持续约21d,每颗卫星每天的观测时间约32min。该结论不仅能够为观测GEO卫星提供参考,也可为分析卫星工作及运动状态提供依据。     

N-type core-shell heterostructured Bi2S3@Bi nanorods/polyaniline hybrids for stretchable thermoelectric generator

With the growing need on distributed power supply for portable electronics,energy harvesting from environment becomes a promising solution.Organic thermoelectric(TE)materials have advantages in intrinsic flexibility and low thermal conductivity,thus hold great prospect in applications as a flexible power generator from dissipated heat.Nevertheless,the weak electrical transport behaviors of organic TE materials have severely impeded their development.Moreover,compared with p-type organic TE materials,stable and high-performance n-type counterparts are more difficult to obtain.Here,we developed a n-type polyaniline-based hybrid with core-shell heterostructured Bi;S;@Bi nanorods as fillers,showing a Seebeck coefficient-159.4μV/K at room temperature.Further,a couple of n/p legs from the PANI-based hybrids were integrated into an elastomer substrate forming a stretchable thermoelectric generator(TEG),whose function to output stable voltages responding to temperature differences has been demonstrated.The in situ output performance of the TEG under stretching could withstand up to 75%elongation,and stability test showed little degradation over a one-month period in the air.This study provides a promising strategy to develop stable and high thermopower organic TEGs harvesting heat from environment as long-term power supply.     

基于实验测量与OCS仿真计算的卫星光学散射特性对比验证

卫星的光度数据与卫星的姿态、材质、观测角度等多种因素有关,仿真计算往往无法获取这些因素,导致仿真计算结果无法与实测进行对比.针对仿真结果无法通过实测进行验证的问题,结合卫星工具箱中卫星运动场景,分别通过实验测量与仿真计算获取卫星光学散射特性的时序数据.实验测量中,在实验室内模拟太空光学环境,实现实验过程中卫星模型姿态与卫星工具箱中卫星姿态的并行分析,保证了测量的准确性.仿真计算中,采用基于前期空间目标常用材质双向反射分布函数实测数据拟合出的双向反射分布函数模型,且考虑卫星表面材料褶皱对空间目标光学散射特性的影响,提高仿真精度.此外,设计了一个轨道参数为:半长轴a=7 716.14km,偏心率e=0.001,轨道倾角i=58°,近日点幅角ω=36°,升交点赤经Ω=345°,平近点角M=231.1°,相位角变化范围为38°~98°的三轴稳定卫星运动场景,通过实验测量与仿真计算获取该场景下卫星的光度数据,发现二者趋势相同,幅值相近,相关系数为0.69.