Plasma transport simulation under different conditions and optimization analysis of dual-stage grid ion thruster

In order to study the extraction and acceleration mechanism of the dual-stage grid, a three-dimensional model based on the Particle-In-Cell/Monte Carlo Collision(PIC/MCC) method is performed. Dual-stage grid ion thruster is a new type of electrostatic ion thruster, which can break through the limitations of traditional gridded ion thrusters, and greatly improve the specific impulse. The high performance also makes the grid sensitive to operating parameters. In this paper,the influence of grid pa...     

基于点云深度学习的对称结构空间目标相对位姿测量

针对对称结构空间目标相对位姿解算过程中点云误匹配带来的误差问题，提出一种基于点云深度学习的对称结构空间目标相对位姿测量方法。首先设计空间目标点云特征提取网络及关键点回归网络，将位姿测量问题转换为空间目标点云关键点回归问题，通过两个并行的回归网络分别输出空间目标平移向量和具有固定标签的目标点云三维边界框角点；其次利用具有连续稳定标签的角点求解目标姿态，可有效解决目标的对称结构导致的点云误配准问题；最后通过仿真数据集的实验表明，该方法相比于传统的点云配准方法有更高的准确率，能够精确求解具有对称结构的空间目标相对位姿。     

拉伸载荷下正交三向机织复合材料接头失效多尺度渐进损伤分析

针对机械打孔三维机织复合材料耳片接头的单轴拉伸破坏性能，采用多尺度分析方法研究孔边纱线破坏过程。结果表明，正交三向（ORT）机织复合材料接头孔边的连续的经纱出现大量的纵向损伤；纬纱单元出现大量横向损伤，损伤沿着孔边45°方向逐渐扩展，纬纱发生剪切失效，最终接头的损伤形式为剪切破坏。数值模拟和试验结果的误差为1.14％，验证了多尺度有限元仿真方法的正确性。孔边细观区域的纱线损伤从孔边扩展到边接头边缘。孔边纱线的分布位置不同，纱线的破坏形式虽不一样，但是不影响破坏的扩展趋势。     

Exploring 2D projection and 3D spatial information for aircraft 6D pose

The 6D pose estimation is important for the safe take-off and landing of the aircraft using a single RGB image. Due to the large scene and large depth, the exiting pose estimation methods have unstratified performance on the accuracy. To achieve precise 6D pose estimation of the aircraft, an end-to-end method using an RGB image is proposed. In the proposed method, the 2D and 3D information of the keypoints of the aircraft is used as the intermediate supervision, and 6D pose information of the aircraft in this intermediate information will be explored. Specifically, an off-the-shelf object detector is utilized to detect the Region of the Interest (RoI) of the aircraft to eliminate background distractions. The 2D projection and 3D spatial information of the pre-designed keypoints of the aircraft is predicted by the keypoint coordinate estimator (KpNet). The proposed method is trained in an end-to-end fashion. In addition, to deal with the lack of the related datasets, this paper builds the Aircraft 6D Pose dataset to train and test, which captures the take-off and landing process of three types of aircraft from 11 views. Compared with the latest Wide-Depth-Range method on this dataset, our proposed method improves the average 3D distance of model points metric (ADD) and 5° and 5 m metric by 86.8% and 30.1%, respectively. Furthermore, the proposed method gets 9.30 ms, 61.0% faster than YOLO6D with 23.86 ms.     

多波束三维成像激光雷达高精度收发匹配方法研究

三维成像激光雷达技术为空间地理信息获取、目标立体探测提供了新的技术途径。以多波束并行收发、单光子阵列探测为特征的新一代三维成像激光雷达可提升雷达探测灵敏度、激光成像帧频与成像效率，从而实现远距离快速激光三维成像。三维成像激光雷达的激光发散角与接收视场需角秒量级的匹配精度。随着系统波束数量的增加，几十甚至上百波束的高精度收发波束匹配是系统设计装调的难点。聚焦多波束单光子阵列三维成像激光雷达的收发匹配难题，设计了基于衍射分束激光发射与光纤阵列接收的收发光学系统，提出了一种多波束激光雷达收发波束匹配方法，并对该方法的收发匹配误差源以及温度对其影响进行了详细分析仿真。实验验证结果表明，可实现64波束优于10 μrad的匹配误差，在工作温度范围内总的收发失配优于20.78 μrad，满足本系统设计时25.5 μrad的收发匹配裕量，系统对环境温度有较好的适应性，具有良好的工程应用前景。     

基于硅基MEMS三维集成技术的片式多波束发射前端

基于多波束发射前端的相控阵,具有波束灵活扫描和多目标同时通信的能力,是低轨互联网通信卫星的重要微波子系统.采用硅基MEMS三维异构集成技术,将多个微波单片集成电路MMIC(Monolithic Microwave Integrated Circuit)和硅基MEMS功分交叉网络等无源结构一体化集成,实现了一种K频段8波...