Concept of the Solar Ring mission: Preliminary design and mission profile

The Solar Ring mission, a concept to monitor the Sun and inner heliosphere from multiple perspectives, has been funded for prephase study by the Strategic Priority Program of Chinese Academy of Sciences in space sciences. The Solar Ring is comprised of 6 spacecraft, grouped in three pairs, moving around the Sun in an elliptical orbit in the ecliptic plane. The mission costs,including launch fee, deep-space maneuvers, and deployment time of the ring, are highly relevant to the working orbit, deepspace transfer, and phase angle within a group. The preliminary mission profile is analyzed and designed in this paper. The launch way, two spacecraft with one rocket, is adopted. The deployment time, phasing maneuvers, and C_3 of launch energy are evaluated for the elliptical orbits with the perihelion between 0.7 and 0.9 AU using the rockets of Long March(LM) 3A and 3B.Numerical simulations show two candidate trajectories: fast deployment within 4 years by LM-3B, medium deployment more than 6 years by cheaper rocket of LM-3A. In order to obtain both fast deployment and low launch cost, another orbit profile is proposed by shortening the phase angle within a group. The suggested working orbits and the corresponding costs of launch,deployment time, and phasing maneuvers will strongly support the science objectives.     

翼伞-载荷系统的航迹跟踪

翼伞-载荷系统可被用于精确空投、定点无损着陆以及大型航天器的回收,在航空航天、军事等领域发挥着非常重要的作用。因此,基于翼伞-载荷系统的八自由度动力学模型,采用横向非线性控制方法,对翼伞-载荷系统的航迹跟踪进行了理论分析与仿真模拟。仿真结果表明,飞行器与参考点之间的较佳距离L1为100 m;该距离内,无风和受到5 m/s常值风情况下,所提出的翼伞-载荷系统均能较好地完成90°,180°,270°,360°转弯的航迹跟踪,说明横向非线性控制方法具有较好的控制性能和一定的抗风能力,可被应用于翼伞-载荷系统的航迹跟踪控制,为翼伞-载荷系统的优化设计以及大型航天器回收的精确控制提供参考。     

Challenges of modeling solar disturbances’ arrival times at the Earth

In recent years remarkable advances have been made in the development of physics based models of various parts of the solar-terrestrial system (see JASTP special issues, October, November 2004; February 2007). In this paper, we focus our discussions in a specific region of the Sun to the Earth’s environment (i.e. 1 AU). It is well-known that geomagnetic storms are caused by solar eruptions. The consequences of these storms include particle acceleration, solar wind impact on the Earth’s magnetosphere and ionosphere, UV-EUV radiation effects on the lower atmosphere, etc. One of the main challenges is to predict the arrival time at 1 AU of the solar disturbance. The prospects look good for an accurate, real-time forecast scheme built on the acquisition of solar, heliosphere and the near-Earth data and large-scale models. However, the accuracy of these models still needs improvement. We will discuss the present status of the models and challenges to improve the simulation models. STW and AHW are supported by AFOSR (Grant No. FA9550-07-1-0468), AURA Sub-Award C10569A of NSO’s Cooperative Agreement AST 0132798, and NSF (Grant No. ATM-0754378); CCW is supported by NASA grant NNX07AH85G, FENG is supported by National Natural Science Foundation of China (Grant Nos. 40536029, 40621003, 40374056 and 40574058)     

An asynchronous and parallel time-marching method: Application to three-dimensional MHD simulation of solar wind

An asynchronous and parallel time-marching method for three-dimensional (3D) time-dependent magnetohydrodynamic (MHD) simulation is used for large-scale solar wind simulation. It uses different local time steps in the corona and the heliosphere according to the local Courant-Friedrichs-Levy (CFL) conditions. The solar wind background with observed solar photospheric magnetic field as input is first presented. The simulation time for the background solar wind by using the asynchronous method is <1/6 of that ...     

缟分形天线

将太阳帆、印刷工艺和分形理论相结合,提出"缟分形天线"的概念.与充气抛物面天线相比,具有精度要求更低、寿命更长、形式灵活多样并可实现多频段通信等优点.线帆合一,可以降低发射成本,简化探测器的结构,提高通信质量和增加系统可靠性.     

Ultra low frequency waves impact on radiation belt energetic particles

One of the most fundamental important issues in the space physics is to understand how solar wind energy transports into the inner magnetosphere. Ultra low frequency (ULF) wave in the magnetosphere and its impact on energetic particles, such as the wave-particle resonance, modulation, and particle acceleration, are extremely important topics in the Earth’s radiation belt dynamics and solar wind—magnetospheric coupling. In this review, we briefly introduce the recent advances on ULF waves study. Further, we will explore the density structures and ion compositions around the plasmaspheric boundary layer (PBL) and discuss its possible relation to the ULF waves.     

Solar wind entry via flux tube into magnetosphere observed by Cluster measurements at dayside magnetopause during southward IMF

By analyzing hot ion and electron parameters together with magnetic field measurements from Cluster, an event of magnetopause crossing of the spacecraft has been investigated. At the latitude of about 40° and magnetic local time (MLT) of 13:20 during the southward interplanetary magnetic field (IMF), a transition layer was observed, with the magnetospheric field configuration and cold dense plasma features of the magnetosheath. The particle energy-time spectrograms inside the layer were similar to but still...     

飞轮储能系统的应用前景

简单介绍了飞轮储能系统（FESS）及组成,着重阐述了飞轮储能系统FESS在风力发电、太阳能发电、不间断电源（UPS）、汽车工业和航天飞行器中的应用,飞轮储能系统有着广阔的应用前景,将成为储能领域国内外学者的研究焦点．     

Quasi-periodic variations of low energy cosmic rays

Cosmic rays(CR)play an important role in space weather-related studies.Their temporal variability,both of a quasi-periodic character as well as an irregular one,has been studied from ground-based direct measurements,as well as from cosmogenic nuclides,over a long time.We attempt to describe the current knowledge of selected quasi-periodicities in CR flux in the energy range above the atmospheric threshold,from direct measurements.The power spectrum density(PSD)of the CR time series as measured by neutron monitors(NMs)and by muon detectors has a rather complicated character.Along with the shape(slope)of the PSD,knowledge of the contribution of quasi-periodic variations(q-per)to the CR signal is of importance for the modulation,as well as for checking the links of CR to space weather,and/or to space climate effects.The rotation of the Earth and solar rotation cause two types of mechanisms behind the certain q-per observed in secondary CR on the Earth’s surface.Solar activity and solar magnetic field cyclicities contribute to the q-per signals in CR if studied over a longer time.The complexity of the spatial structure of the interplanetary magnetic field(IMF)and its evolution within the heliosphere,in addition to the changes in the geomagnetic field,cause variability in contributions of the q-per in CR.Wavelet spectra are useful tools for checking the fine structure of q-per and their temporal behaviour.Over a long time NMs and muon telescopes provide information about q-per in CR.     

不确定性条件下的深空探测器观测调度

以不确定性条件下的深空探测器观测调度问题为研究对象,首先分析了深空探测任务的背景特点,指出深空探测活动具有高度不确定性,进而全面分析了深空探测器观测调度中的不确定性因素,提出了基于鲁棒调度和动态重调度的深空探测器调度体系,并针对其中的动态重调度单元进行了深入研究。详细设计了改进的混合动态重调度策略和基于群体智能的深空探测器动态重调度方法,最后提出了基于时间成本、效率和稳定性的重调度性能评价体系。     

航天器微流星和空间碎片的防护方案

微波星和空间碎片是现在任何使用航天器的公认威胁。微流星和空间碎片的超高速撞击能导致航天器严重的损伤和灾难性的失效。因此,提高航天器的生存性是非常必要的。防护方案的确定是航天器设计的一个重要问题。     

近地小行星探测转移轨道方案设计与优化

探测小行星转移轨道的设计不同于传统的飞行器轨道设计,由于需要更多的能量,仅依靠冲量轨道转移难于实现,针对此问题,以近地小行星3288 Seleucus为例,采用了先将飞行器递推至以2 a为周期的日心大椭圆轨道的远日点,加深空机动使之再次与地球相遇,进行借力飞行的轨道转移技术,设计了其转移轨道.为了进一步减少此探测任务在轨道转移方面所需的总的能量,采用了变分与主矢量原理推导出了总的速度增量对自由变量的偏导数,把复杂的多维非线性轨道优化问题归结为一个多维参数优化问题,并利用梯度下降法,对所设计的探测3288 Seleucus小行星的转移轨道方案进行了优化.数学仿真结果表明:这种地球借力飞行的轨道转移技术可有效的降低完成任务所需的总能量,特别是发射时所需的能量.     

航天器微流星体及空间碎片防护结构性能分析

微流星体及空间碎片是航天器的公认威胁，微流星体及空间碎片的高速撞击能导致航天器严重的损伤和灾难性的失效，防护结构设计是航天器设计的一个重要问题，在综合分析国际上已采用和研究航天器微流星体系及空间碎片防护结构防护性能预报方程的基础上，给出了不同防护材料和结构形式防护在超高速撞击下的撞出极限曲线，讨论了防护结构参数变化对防护性能的影响，通过曲线分析得出各防护结构在第一门槛值速度区间的防护性能是比较低的，正撞击损伤更严重，填充防护结构的性能优于其他防护结构。     

Dynamic variations of the outer radiation belt during magnetic storms for 1.5–6.0 MeV electrons

The CME’s structure of solar wind (interplanetary magnetic field) is different from CIR’s. The two processes in which plasma and solar wind energy are injected into the Earth’s inner magnetosphere are not the same. So, the variations of energetic electrons flux in the radiation belts are different between the storms associated with CMEs and CIRs. By using data from SAMPEX (Solar, Anomalous, and Magnetospheric Particle Explorer) satellite, we have investigated the dynamic variations of the outer radiation belt for 1.5–6.0 MeV electrons during 54 CME-driven storms and 26 CIR-driven recurrent storms. According to the superposed epoch analysis, for CME- and CIR-driven storms, when the Dst index reaches the minimum, the locations of the outer boundary move to L=4 and L=5.5, respectively. In the recovery phases, the locations of the outer boundary of the outer radiation belt are generally lower than and slightly higher than those before CME- and CIR-driven storms, respectively. We have found that the logarithmically decaying 1/e cut-off L-shell is a satisfying indicator of the outer boundary of the outer radiation belt. Furthermore, our study shows that the logarithmically decaying 1/e cut-off latitude is dependent on the Kp index in the main phases of CME- and CIR- driven storms, while in the recovery phases, there is no obvious correlation. In addition, it has been shown that the locations of the peak electron flux are controlled by the minimum Dst index in the main phases of CME-driven storms. The influences of multiple storms on the electron flux of outer radiation belt have also been investigated.

     

基于Hydrolight模拟的内陆水体光场的二向性

为了进一步完善内陆水体光场的二向性研究,以水体固有光学量和水质参数为输入,采用Hydrolight辐射传输模型模拟了内陆水体光场的二向性分布,获得了二向性因子Q、f/Q随观测方向、波段的变化规律以及Q、f/Q受驱动要素的影响规律.结果表明:f/Q随波段的变化大于随观测天顶角和观测方位角的变化,f/Q随观测天顶角变化大于随观测方位角的变化;观测方向对蓝光和近红波段f/Q的影响大于对绿光和红光f/Q的影响.Q、f/Q的驱动要素中太阳天顶角、悬浮物质量浓度、叶绿素a质量浓度、悬浮物后向散射概率及云量属于主导要素,在反演浑浊类水体水质参数时需要慎重对待;aCDOM、叶绿素后向散射概率、漫总比、风速等要素对光场二向性的影响可以忽略.总体而言,仅考虑二向性影响时,水质参数遥感反演时应尽量选用绿光和红光波段、观测天顶角在40°范围内、观测方位角在0°~150°和210°~360°内的遥感反射率数据,可以适当降低方向性观测引入的误差,提高水质参数反演精度.     

近空间飞行器及其军事应用分析

近空间是陆、海、空、天之外又一新的军事应用空域,它将成为联合作战空间的重要组成部分.近空间飞行器可有效弥补军用航天器和军用航空器的不足,提高武器装备的联合应用能力,增强整体作战效能,具有重要的军事应用价值.探讨了近空间和近空间飞行器的概念;根据近空间的环境特性,总结了近空间飞行器的特点;并着重对近空间飞行器的军事应用前景进行了深入分析.     

民用建筑太阳能的利用

太阳能技术包括太阳能光电技术与太阳能光热技术。太阳能不会对环境产生污染,且可永久获得,因而太阳能光热利用将成为世界上最大的节能减碳项目之一。然而在我国民用建筑太阳能使用和推广中已出现诸多问题:太阳能光热产品市场无序竞争,小区住户安装太阳能光热产品遇到技术、管理和法律层面的阻碍。建议地方政府制定相关节能强制政策与技术规范,主要包括:制定民用建筑太阳能热利用强制政策和太阳能建筑一体化技术规范,清晰楼顶产权,建立政府补贴制度,成立太阳能光热利用专业指导委员会,从而实现节能减排与促进低碳经济的发展。     

Prediction method for October 2003 solar storm

Aiming at two intense shock events on October 28 and 29, 2003, this paper presents a two-step method, which combines synoptic analysis of space weather ——“observing” and quantitative prediction ——“palpating”, and then uses it to test predictions. In the first step of “observing”, on the basis of observations of the solar source surface magnetic field, interplanetary scintillation (IPS) and ACE spacecraft, we find that the propagation of the shocks is asymmetric relative to the normal direction of their solar sources, and the Earth is located near the direction of the fastest speed and the greatest energy of the shocks. As the two fast ejection shock events, the fast explosion of coronal mass of the extremely high temperature, the strong magnetic field, and the high speed background solar wind are also helpful to their rapid propagation. In the second step of “palpating”, we adopt a new membership function of the fast shock events for the ISF method. The predicted results show that for the onset time of the geomagnetic disturbance, the relative errors between the observational and the predicted results are 1.8% and 6.7%; and for the magnetic disturbance magnitude, the relative errors are 4.1% and 3.1%, re- spectively. Furthermore, the comparison among the predicted results of our two-step method with those of five other prevailing methods shows that the two-step method is advantageous. The results tell us that understanding the physical features of shock propagation thoroughly is of great importance in improving the prediction precision.     

一种基于空间燃料站的GEO航天器在轨加注任务调度算法

本文针对多GEO航天器在轨燃料加注任务,对基于燃料站的在轨加注模式进行了研究,提出了一种基于燃料站的可往返式在轨加注任务调度及优化算法。通过对双脉冲轨道转移问题的求解与分析,获得了轨道转移速度增量和转移时间之间的关系,在此基础上提炼出了基于燃料站的多GEO航天器在轨加注任务调度模型,并根据调度模型的变量和约束关系,建立了考虑在轨加注作业顺序和作业时间分配优化的多GEO航天器在轨加注任务多目标优化模型,并采用遗传算法对加注任务调度及其多目标优化问题的求解方法进行了研究。为了验证算法的有效性,以为20颗GEO圆轨道目标航天器的在轨加注任务为例,进行了数值仿真计算,结果表明算法是有效的。     

屋面光伏阵列荷载分析与结构承载力评估

太阳能是一种洁净能源,太阳能发电前景非常广阔.由于现有土地较为紧张,目前太阳能发电一般借助既有的建筑物实现发电与建筑物一体化.对新增光伏发电设备的建筑物,需核算增加设备荷载后既有建筑是否满足承载力要求;目前,国家规范对光伏发电设备的荷载计算没有专门的阐述,因此,设计时使用的标准各不相同.本文参考国外现有设计经验及现行相关规范,将计算结果进行对比后,提出较为常规的荷载计算方法及建筑物的承载力评估方法.