Solar activity prediction studies and services in NAOC

Solar activity prediction services started in 1960’s in National Astronomical Observatories, Chinese Academy of Sciences (NAOC). As one of the members of the International Space Environment Service (ISES), Regional Warning Center of China (RWC-China) was set up in 1990’s. Solar Activity Prediction Center (SAPC), as one of the four sub-centers of RWC-China, is located in NAOC. Solar activity prediction studies and services in NAOC cover short-term, medium-term, and long-term forecast of solar activities. Nowadays, certain prediction models, such as solar X-ray flare model, solar proton event model, solar 10 cm radio flux model, have been established for the practical prediction services. Recently, more and more physical analyses are introduced in the studies of solar activity prediction, such as the magnetic properties of solar active regions and magnetic structure of solar atmosphere. Besides traditional statistics algorithms, Machine Learning and Artificial Intelligence techniques, such as Support Vector Machine (SVM) method, are employed in the establishment of forecast models. A Web-based integrated platform for solar activity data sharing and forecast distribution is under construction.     

Radar target novel characteristic detection method

In this paper, a method of radar target detection based on 2-dimensional (2D) fractal dimension is proposed. The proposed approach exploits both range information and azimuth information to estimate fractal dimension. Moreover, the approach can increase the number of the data points. The above two merits result in the fractal dimension estimated by this method is more accurate and robust than the previous method. The detection performance is also better than the previous one, which only makes use of 1-dimensional (1-D) information to estimate fractal dimension. Theoretical analysis and experimental result show that the proposed method performs well in strong clutter background. The proposed method is also validated by real-life radar data, and the better result has been achieved.     

无人机飞行控制系统先进设计技术评述

首先简要回顾了无人机飞行控制系统经典设计方法,然后着重论述了目前国外在无人机飞行控制系统设计领域的最新研究成果,包括动态逆技术、BACKSTEPPING自适应技术及综合制导与控制技术。     

提高花键加工精度的工艺研究

发动机中力及扭矩的传递全部通过渐开线花键副来实现,由于发动机工作转速高,因而要求渐开线花键副传动非常平稳。通过本工艺方法的探索,采用新的工艺加工方法,提高了涡轮泵叶轮、轴的花键加工精度,保证了涡轮泵装配性能的要求。     

Predicting performance in manually controlled rendezvous and docking through spatial abilities

Manually controlled rendezvous and docking (manual RVD) is a challenging space task for astronauts. This study aims to identify spatial abilities that are critical for accomplishing manual RVD. Based on task analysis, spatial abilities were deduced to be critical for accomplishing manual RVD. 15 Male participants performed manual RVD task simulations and spatial ability tests (the object-manipulation spatial ability and spatial orientation ability). Participants’ performance in the test of visualization of viewpoints (which measures the spatial orientation ability) was found to be significantly correlated with their manual RVD performance, indicating that the spatial orientation ability in the sense of perspective taking is particularly important for accomplishing manual RVD.     

The Kumtag meteorite strewn field

The Kumtag meteorite strewn field was found in the Kumtag desert, 132 km south of Hami city in the Xinjiang province, China. It is an ellipse of 2.5 × 7.9 km, with a long axis extending along the northeast-southwest direction. The largest individual meteorite of the strewn field weighs about 10 kg; the smallest individual has a mass of only 27 g. In total, more than 100 individuals with a total mass of more than 180 kg were collected. The location and the distribution of the fragments suggest that the Kumtag meteoroid entered the atmosphere in the direction Northeast-Southwest. All meteorites collected in this strewn field are samples from the same unique meteorite shower. The Kumtag meteorite is an H5 ordinary chondrite with a shock stage S2, and a weathering grade W2. The cosmic ray exposure age of Kumtag is 6.7 ± 0.8 Ma, which is rather typical for H chondrites and which indicates that Kumtag was derived from the massive impact event on its parent body ~7 Ma ago. A significant amount of He has been lost during certain unknown processe(s) before the Kumtag meteorite was ejected from its parent body.     

进气畸变对某压气机一级叶片振动的影响

本文定量地分析了进气畸变激起的 -级叶片的振动应力, 分析了在不同畸变水平下对应的应力变化趋势, 并从叶片振动响应角度对评定畸变容限指标的方法进行了初步讨论。      

1986年2月4日AR4711拱形双带黑子暗条系激活的分析

根据1986-02-04AR47ll由观测所确定的物理参数和特征值,采用电动力学方法数值计算该活动区中两个拱形黑子暗条在大耀斑爆发前的动力学演化过程.结果表明:(1)以旋涡黑子为标志的光球物质旋转运动和以暗条下方磁力线强剪切为特征的剪切运动引起暗条电流增加和背景磁场变化,电流和磁场的相互作用导致暗条向上运动,大耀斑爆发前暗条的上升速度达26km／S;(2)背景场位形对暗条整体动力学行为有很大影响,AR47ll在7×104km高度范围内场强随高度似乎按指数规律衰减.      

用于平板智能复合材料的拟温度载荷法

针对探测和控制裂纹扩展的平板智能复合材料结构特点, 提出和建立了一新的应力分析方法--拟温度载荷法, 并且利用此方法对所设计的几种不同的结构模型进行了理论分析。通过试验证明了该计算方法的正确性, 该计算方法的提出和建立, 为进行控制裂纹扩展的智能材料结构研究和应用奠定了重要的理论分析基础。      

碳纤维增强复合材料与高强度金属的接触腐蚀

碳纤维/环氧树脂复合材料(CFRM)与高强度钛合金、铝合金、1Cr18Ni9Ti不锈钢等结构材料连接时,在界面形成了电偶腐蚀和缝隙腐蚀,这首先决定于材料本身的电化学性能;同时,也与相互的配偶情况、处理工艺和环境条件有关。电偶腐蚀受配偶材料各自的静态自腐电位(E_(corr))和电偶电位、电偶电流等闭路动态性能的影响。在3.5％NaCl溶液中,材料电化学特性和处理工艺对电偶腐蚀及缝隙腐蚀影响的趋势相同。用浸泡失重法、盐雾试验法及缝隙腐蚀法检验CFRM与阳极化钛合金,以及热水封和铬酸盐封闭的铝合金偶接时,稳定性较好,可满足工程应用的需要。