Planetary protection on international waters: An onboard protocol for capsule retrieval and biosafety control in sample return mission

Planetary protection has been recognized as one of the most important issues in sample return missions that may host certain living forms and biotic signatures in a returned sample. This paper proposes an initiative of sample capsule retrieval and onboard biosafety protocol in international waters for future biological and organic constituent missions to bring samples from possible habitable bodies in the solar system. We suggest the advantages of international waters being outside of national jurisdiction and active regions of human and traffic affairs on the condition that we accept the Outer Space Treaty. The scheme of onboard biological quarantine definitely reduces the potential risk of back-contamination of extraterrestrial materials to the Earth.     

Lunar geophysical parameters inversion based on gravity/topography admittance and particle swarm optimization

This paper presents a FORTRAN computer program. The program as code will be used for lunar parameter inversions based on gravity/topography admittance. This will be done by assuming that the lunar lithosphere is modeled as a thin elastic spherical shell. The parameters discussed here include; load ratio, crustal thickness, subsurface load depth, crustal density and elastic lithosphere thickness. The admittance of the best-fitting model can be found through automatically adjusting misfits between one theoretical admittance and an observed one. The results in this paper indicate that this research’s theoretical model is reasonable for exploring the best-fitting parameters. In addition, this code is not only able to automatically and simultaneously calculate the global optimum solution of the parameters studied, but also performs well in computational speed. The code can be easily modified to include more parameter inversions; such as the inversion for subsurface density anomaly and the case of considering infilling material in some lunar mare basins.     

火星进入气体辐射加热研究进展

针对飞行器进入火星大气时气体辐射加热对防热设计带来不确定性，在简述火星探测和气体辐射研究的发展历程的基础上，对火星进入气体辐射加热研究的进展进行综述。首先，针对火星大气环境描述了气体辐射加热的概念和问题由来。其次，重点综述了近年来火星进入气体辐射加热基础模型的数值和试验研究进展，其中包括：热化学非平衡气体动力学、气体辐射特性和辐射传输的计算模型与方法等数值研究；地面测试设备、试验技术和模拟火星大气环境的气体辐射测量与验证等试验研究。再次，综述了流动辐射耦合和后体气体辐射加热等火星进入器设计方面开展的研究。最后，对未来火星进入气体辐射加热研究进行了展望，提出了研究建议。     

基于增量学习的高光谱图像目标检测

高光谱图像目标检测是高光谱图像分析中的重要研究内容之一。本文从经典有效的约束能量最小化算法出发,提出了一种基于增量学习的高光谱目标检测方法。当获得新的样本时,不需要重新计算所有样本的自相关矩阵即可对检测器模型进行更新,减轻了星上有限计算资源的负担。实验结果表明:本文提出的目标检测算法在压制背景光谱的同时可以更好地适应目标光谱,提高了算法的检测性能。     

TS-InSAR analysis for monitoring ground deformation in Lanzhou New District,the loess Plateau of China,from 2017 to 2019

Large-scale land creation projects involving the cutting of mountains to infill gullies for construction have been carried out in Lanzhou New District (LZND). However, there is an urgent need for comprehensive and detailed research on the spatiotemporal evolution of ground deformation in LZND. Based on Sentinel-1A SAR data, combined with the urban geological background, the ground deformation in LZND from 2017 to 2019 was analysed. Two independent, multi-temporal techniques, persistent scatterers interferometry (PS-InSAR) and the small baseline subset (SBAS-InSAR), were used to calculate the deformation time series, and the results were cross-verified. The time series-monitoring results of the SBAS and PS calculations exhibited strong consistency in LZND and verified the high reliability of the experimental results. The results showed the whole surface of the LZND from March 2017 to October 2019 maintained stability, and the deformation rate was primarily in the range of ?10 to 10 mm/year. However, ground deformation in the Xicha area was evident. The maximum annual deformation rates monitored by SBAS-InSAR and PS-InSAR were ?52.48 mm/year and ?56.35 mm/year, respectively. The most typical deformation areas include the built-up area and the land creation area. The surface subsidence area was concentrated in the filling area. The ground deformation range of LZND kept expanding and accelerating from 2017 to 2019. Land creation, urban construction, geology and precipitation were the primary factors contributing to local severe ground deformation. The results of this study provide reference for the regional urban planning in LZND.     

焊缝补强方式对大直径贮箱箱底承载性能影响

基于有限元法研究了典型10 m级直径贮箱箱底焊缝在双面对称补强、内表面补强及外表面补强三种情况下的内压承载性能。数值计算采用二维对称平面模型,考虑了筒段和短壳真实边界条件及焊缝对承载能力的影响,构建的考虑材料塑性的非线性数值分析模型准确地获得了贮箱箱底内外表面经向应力。结果表明:顶盖和瓜瓣焊缝区域是箱底的薄弱位置,使用内压下,双面对称补强的加强区内外表面经向应力差较小,结构均未进入塑性,单面补强的加强区内外表面经向应力差远大于双面对称补强,局部进入塑性,且外表面补强的加强区最大和最小经向应力差相对于内表面补强分别增加了9.7%和27.2%,变形不协调；设计内压下,箱底内外表面均有局部进入塑性,材料塑性对内外表面经向应力差有一定的缓解作用,能够显著缓解内外表面应力差造成的附加弯矩；双面对称补强优于内表面补强,内表面补强优于外表面补强,单面补强易产生附加弯矩,不利于箱底的均匀承载和变形协调。该研究结果指导了大直径贮箱箱底结构的优化设计。     

嵌入式大气数据测量系统技术研究进展

针对高超声速飞行器大气数据测量问题，对嵌入式大气数据测量系统(FADS)技术研究背景、发展历程、国内外研究现状等进行了概括。重点围绕FADS关键技术、FADS解算算法及面向FADS/INS组合测量系统信息融合算法方面，对FADS技术进行了深入的剖析。最后，展望了FADS技术未来的发展方向及应用前景。     

Possible evidence for small-scale wave seeding of equatorial plasma bubbles

The small-scale wave-like structure (SSWS) of F region bottomside plasma density was proposed to be an important seeding for equatorial plasma bubble (EPB) generation, and employed in theoretical simulations of EPBs in recent years. The seeding role of SSWS, however, is waiting to be demonstrated by observation. Here we present two cases of SSWS and EPB observed by the Fuke all-sky airglow imager (19.3°N, 109.1°E; dip latitude 14.3°N). For each case, the results show that two large-scale wave-like structures (LSWSs) initially appeared around sunset in the longitude regions separated by 3–4°, but EPB irregularities were only generated in one of the LSWSs where SSWSs were seen riding on LSWS. For the other LSWS, no SSWS and EPB irregularities were seen. Considering that the two LSWSs were situated closely in longitude where the amplitude of pre-reversal enhancement of background eastward electric field should be similar, the observation that EPB was only generated in the longitude with simultaneous LSWS and SSWS could provide supporting evidence for SSWS seeding of EPB.     

Application of novel force control strategies to enhance robotic abrasive belt grinding quality of aero-engine blades

Robotic belt grinding has emerged as a finishing process in recent years for machining components with high surface finish and flexibility.The surface machining consistency, however,is difficult to be guaranteed in such a process.To overcome this problem, a method of hybrid force-position control combined with PI/PD control is proposed to be applied in robotic abrasive belt grinding of complex geometries.Voltage signals are firstly obtained and transformed to force information with signal conditioning methods.Secondly, zero drift and gravity compensation algorithms are presented to calibrate the F/T transducer which is installed on the robot end-effector.Next, a force control strategy combining hybrid force-position control with PI/PD control is introduced to be employed in robotic abrasive belt grinding operations where the force control law is applied to the Z direction of the tool frame and the positon control law is used in the X direction of the tool frame.Then, the accuracy of the F/T transducer and the robotic force control system is analyzed to ensure the stability and reliability of force control in the robotic grinding process.Finally, two typical cases on robotic belt grinding of a test workpiece and an aero-engine blade are conducted to validate the practicality and effectiveness of the force control technology proposed.     

PIV 技术测量振荡射流流场

利用以大功率双脉冲激光器为光源的ＰＩＶ技术，测定了由扁平射流和尖劈组成的二维振荡射流流场。实验结果表明，射流喷嘴与尖劈之间存在交错的、旋转方向相反的涡街，从而在尖劈两侧形成压力扰动。这种压力扰动波与不稳定射流的相互作用是整个系统产生流体振荡的原因。此外，还分析了射流喷嘴与尖劈之间的距离对流场的影响规律。