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为了研究地球同步轨道量子密钥分发过程中星地量子信道特性,项目团队研制了搭载于实践二十卫星的极弱光偏振态分发设备,开展了地球同步轨道卫星与地面间光子偏振态的传输实验。实验时,星载偏振光分发设备根据遥控指令以50MHz频率驱动四个激光器出光,分发|0〉、|π/2〉、|π/4〉和|3π/4〉四种偏振态光子,经过长距离的空间传输后由地面站望远镜接收,最后由超导探测器探测。研究结果表明,地球同步轨道卫星到地面站的光学链路衰减约为100~110 dB,通道误码率约为2%~8%,满足量子密钥分发误码率的安全性要求。 相似文献
83.
Yuan Xiao Yan Su Shun Dai Jianqing Feng Shuguo Xing Chunyu Ding Chunlai Li 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2019,63(10):3404-3419
The Lunar Regolith Penetrating Radar (LRPR) is an Ultra-Wideband (UWB) array-based Ground penetrating radar (GPR) onboard the lander of Chang’e-5 (CE-5) mission. The primary scientific objectives of the LRPR are to probe the thickness and structure of lunar regolith of the landing site, and support the drilling and sampling process. In order to evaluate the performance of the LRPR, a series of ground experiments are performed using the LRPR prototype mounted on a CE-5 lander model. The performance of the LRPR is evaluated by comparing the experimental data with the simulated data. Data processing and imaging method are verified, and the interferences from the lander and other aspects are analyzed. The results of the ground experiments and simulation demonstrate that the LRPR is able to meet the design requirement of 2-m detection depth. They also indicate that the upper and lower interfaces of the stratified structure in the lunar regolith can be well distinguished by the LRPR when the dielectric constant difference is greater than 0.3, and the imaging effect of the location under the dense antennas is better than that of other positions. However, the identification capability of the LRPR to the independent blocky objects is relatively poor mainly due to the clutters caused by the lander, the sparsity of the antenna elements compared to the size of the basalt block, the limited aperture of the antenna array, and the tail of the transmitted waveform. 相似文献
84.
嫦娥五号探测器月面采样封装任务需利用采样机械臂及其末端执行机构夹持样品容器,为克服非结构化月面环境对机械臂控制造成的不可知影响,确保精确夹持样品容器,提出并设计了一种视觉伺服样品容器夹持的控制方法和系统。系统通过固定安装相机和"眼在手"相机协同获取机械臂末端执行机构以及样品容器特征,采用扩展卡尔曼滤波算法对机械臂末端执行机构位姿的控制参数进行估计,消除控制位姿的轨迹抖动,实现了对样品容器的精确夹持。最后,通过分析在轨月球样品容器被夹持过程的数据和图像,验证了该视觉伺服控制方法和系统设计正确有效。 相似文献
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Wei LIU Xin MA Ling CHEN Zhenyuan JIA Weixiao LIU Xiao LI Jiakun ZHANG Jiwen LU 《中国航空学报》2018,31(1):89-98
The measurement of position and attitude parameters for the isolated target from a high-speed aircraft is a great challenge in the field of wind tunnel simulation technology. This paper proposes a remote-controlled flexible pose measurement system in wind tunnel conditions for the separation of a target from an aircraft. The position and attitude parameters of a moving object are obtained by utilizing a single camera with a focal length and camera orientation that can be changed based on different measurement conditions. Using this proposed system and method, both the flexibility and efficiency of the pose measurement system can be enhanced in wind tunnel conditions to meet the measurement requirements of different objects and experiments, which is also useful for the development of an intelligent position and attitude measurement system. The position and the focal length of the camera also can be controlled remotely during measurements to enlarge both the vertical and horizontal measurement range of this system. Experiments are conducted in the laboratory to measure the position and attitude of moving objects with high flexibility and efficiency, and the measurement precision of the measurement system is also verified through experiments. 相似文献
88.
Honglei Ma Feng Zhang Yu Zhu Yanhua Xiao Abrar Wazir 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
The purpose of the present study was to analyze and predict the changes in acceleration tolerance of human vertebra as a result of bone loss caused by long-term space flight. A human L3–L4 vertebra FEM model was constructed, in which the cancellous bone was separated, and surrounding ligaments were also taken into account. The simulation results demonstrated that bone loss has more of an effect on the acceleration tolerance in x-direction. The results serve to aid in the creation of new acceleration tolerance standards, ensuring astronauts return home safely after long-term space flight. This study shows that more attention should be focused on the bone degradation of crew members and to create new protective designs for space capsules in the future. 相似文献
89.
从带电表面微元出发,通过求解泊松方程,得到带电介质平板表面邻近空间静电势的解析表达式,建立介质表面电位-介电常数模型,求得了带电介质平板表面电位、表面带电量和介质介电常数三者之间的关系式。结合典型的航天器表面介质材料带电案例,对此类圆盘结构介质平板带电问题进行了仿真分析,结果表明,在介质材料表面电位一定的情况下,表面电荷激发的空间静电势值随距离的增大而减小,并且距离介质表面越近,电势的空间变化率越大;在介质材料带电量相等的情况下,介质表面电位随着介质介电常数的增大而减小,并逐渐趋于一个稳定值,所以在一定范围内选择介电常数较大的介质材料可以降低介质的表面电位,减小介质间发生静电放电的几率。 相似文献
90.