Millstone地区垂直等效风场的气候学变化

基于1976---2006年美国Millstone非相干散射雷达的电离层观测数据, 分析了美国Millstone地区不同太阳活动条件下, 包括中性风场和电场漂移共同贡献的垂直等效风场的变化特征. 结果表明, Millstone地区的垂直等效风场表现出比较明显的周日、太阳活动和季节变化特征. 晚间垂直向上的等效风较强, 白天等效风较弱, 甚至接近于零. 在不同太阳活动和季节变化条件下, Millstone地区的等效风场都表现出类似的周日变化特征, 低太阳活动条件下, 晚间表现出较大的向上漂移. 这种周日变化和太阳活动变化特征与Millstone地区受到极区热源驱动大气循环的调制以及离子曳力的增减有关. 春季和秋季有相似的幅度和相位变化趋势, 表现出分点对称性; 冬季晚间向上漂移比夏季弱, 且随着太阳活动增强, 差异更加明显, 这再次体现了极区热源驱动大气循环的影响.     

Structural Analysis About a New Solar Sail

The article presents a structural analysis of a new space probe-solar sail. It was deployed successfully on ground. The loads for an outer space mission was introduced and expressed with equation. As a special state, the largest load around earth was used to analyze the model by the finite element method. Some results about strain and stress was obtained after setting some initial parameters. Compared to the results in the literature, the results presented here are significant.     

Progress of Solar Corona Study in China

Solar corona study is an important aspect of space weather research.In recent years,great achieVements have been acquired on the solar corona study by the space physics group of China.This paper gives a brief outline of these progresses that have been made during 2006--2008.This kind of research includes observational study of the corona,theoretical investigations,statistical analysis based on a large number of data sets,numerical method for MHD modeling,numerical study of space weather events,and prediction methods for the complicated processes originating from the solar corona.Each is given as a separate part in the following.     

太阳系边际探测飞行任务规划

针对太阳系边际探测任务,开展了星际多目标飞越的任务规划,采用小推力混合优化设计方法完成了基于借力飞行及电推进技术的行星际转移轨道联合优化设计,对比研究了面向日球层鼻尖和尾部探测的星际多目标探测飞行方案。研究表明,探测器在2024-2025年发射,可飞抵日球层鼻尖区域,在2027-2030年发射可飞抵日球层尾部区域,并可在2049年1月1日前飞离日心100 AU,实现太阳系边际空间的科学探测。其中日球层鼻尖探测任务探测器飞抵100 AU的位置位于鼻尖中心区域,可与旅行者1号、2号探测器形成有效互补。文章所用任务规划方法,可为太阳系边际探测的自主任务规划技术提供基础,相关研究成果能够为未来中国首次太阳系边际探测任务的实施提供有价值的参考。     

2005年8月24日强磁暴事件对高层大气密度的扰动

对2005年8月24日发生的突发型强磁暴(Kp峰值达到9)事件,利用星载大气密度探测器在轨实时的连续探测数据进行了处理和分析.结果表明,此次强磁暴事件期间,引起560 km高度附近大气密度剧烈扰动,并存在着两种响应过程.一种是跟随地磁扰动程度变化的全球性大气密度涨落变化,响应时间滞后6h左右, 最大涨落变化比为2.5;另一种为磁暴峰期出现在高纬地区的大气密度突发性跃增,增变比高达5.5.后者存在着区域上的不对称性及时间上的突发性和增幅的差异.此次强磁暴峰期还同时出现了南北半球高纬地区的大气密度跃增双峰.同时还表明这种增变峰可能存在着由高纬向低纬地区迅速推移的现象,在中纬地区推移速度可达15°/h(纬度)左右.      

Some Properties of Microwave Emission From Flaring Regions

A study is made of the differences in the polarization distribution and other characteristics of microwave emission for several active regionswith high flare productivity. Conclusions are drawn about the magnetic field structure of these regions at coronal heights.     

550～600 km高度上热层大气密度的中长期变化

选用了2005年8月20日至2006年7月28日高度550～600 km附近的热层大气密度探测数据,对表征太阳活动的F10.7值和表征地磁活动强度的Ap指数进行了相关特性的统计.分析结果表明,在无明显地磁扰动时热层大气密度日平均值的涨落呈现27日和准半年的周期性变化,但在地磁扰动期间这种变化的周期性会被削弱,且大气密度的周日变化幅度与F10.7值呈正相关关系.     

利用行星际监测数据进行地磁暴预报

利用全连接神经网络方法应用于地磁Dst指数的预报中.对ACE卫星探测的太阳风和行星际磁场及其变化对未来几小时的Dst指数的影响进行了统计分析,发现在这些行星际实测参数中,对Dst指数作用较为明显的是太阳风速度、太阳风质子密度和行星际磁场南向分量,同时,当前Dst指数实测值对今后几小时的Dst指数已有很强的制约作用.在统计分析的基础上,建立了全连接神经网络预报模型.由于采用了全连接神经网络结构,模式能够反映出太阳风、行星际磁场等参数与地磁Dst指数参数的复杂联系,可以自动建立输入参量的最佳组合方式,提高了预报精度.通过利用大量实测数据对神经网络模式进行训练,最终建立了利用优选的ACE卫星行星际监测数据提前2 h对Dst指数进行预报.通过检测,预报的误差为14.3%.     

Solar sail attitude control using shape variation of booms

Active attitude control of solar sails is required to control the direction of the force generated by Solar Radiation Pressure (SRP). It is desirable to control the attitude through propellant-free means. This paper proposes a new method for attitude control of solar sails: A boom consisting of “smart” structural material can be deformed by the piezoelectric actuator, and Solar Radiation Pressure torque will be generated due to shape variation of sail membrane caused by boom deformation. The method has the advantages of simple structure, small disturbance and small additional load, and is not limited by the size of the solar sail. The case of rendezvous with the Asteroid 2000 SG344 is used to verify the attitude control around the pitch and yaw axes.     

Dynamic modeling and beating phenomenon analysis of space robots with continuum manipulators

Space robotics has been used extensively in complex space missions. Rigid-manipulator space robots may suffer from rigid-body collisions with targets. This collision is likely to cause damage to the space robot and the target. To overcome such a problem, a novel Continuum-Manipulator Space Robot (CMSR) for performing on-orbit servicing missions is proposed in this paper. Compared with rigid-manipulator space robots, CMSRs are able to perform compliant operations and avoid rigid-body collisions with a target. The CMSR consists of two kinds of flexible components, including solar arrays and continuum manipulators. The elastic vibrations of these flexible components disturb the position and attitude of CMSRs. The beating phenomenon introduced by the energy transfer among these flexible components can cause damage to solar arrays. The complicated dynamic coupling poses enormous challenges in dynamic modeling and vibration analysis. The dynamic model for CMSRs is derived and the mechanism of the beating phenomenon is analyzed in this paper. Simulation results show that an obvious beating phenomenon occurs and the amplitude of the solar arrays increases significantly when the natural frequencies of two kinds of flexible components are close. A method is provided to avoid the beating phenomenon.