行星际高速公路技术

介绍了行星际高速公路技术的研究背景，有条件地分析了行星际高速公路技术的限制性三体问题、混沌动力学问题和行星际高速公路的描述与计算问题，最后探讨了行星际高速公路在低能量星际转移轨道设计中的应用和在未来星际城市开发中的潜在价值。     

高校图书馆电子化建设

扼要介绍了南京航空航天大学图书馆最近几年在建设电子化、网络化基础设施，建立电子文献资源，配套相应服务等方面所作的努力。     

Substorm activity during the main phase of magnetic storms induced by the CIR and ICME events

In this work, the relation of high-latitude indices of geomagnetic activity (AE, Kp) with the rate of storm development and a solar wind electric field during the main phase of magnetic storm induced by the CIR and ICME events is investigated. 72 magnetic storms induced by CIR and ICME events have been selected. It is shown that for the CIR and ICME events the increase of average value of the Kp index (Kp_aver) is observed with the growth of rate of storm development. The value of Kp_aver index correlates with the magnitude of minimum value of Dst index (|Dst_min|) only for the ICME events. The analysis of average values of AE and Kp indices during the main phase of magnetic storm depending on the SW electric field has shown that for the CIR events, unlike the ICME events, the value of AE_aver increases with the growth of average value of the electric field (Esw_aver). The value of Kp_aver correlates with the Esw_aver only for the ICME events. The relation between geomagnetic indices and the maximum value of SW electric field (Esw_max) is weak. However, for the ICME events Kp_aver correlates with Esw_max.     

深空通信中的网络技术

介绍了深空通信的特点、目前空间链路所使用的数据传输协议对深空探测环境的适用性、新制订容延迟网络体系结构的设计思想和实现要点,以及有待进一步研究的内容。     

行星际互联网中基于Raptor码的分布式存储策略

针对行星际互联网节点存储资源严重受限及存储可靠性问题,提出一种基于Raptor码的分布式存储策略(DSSR)。采用定向随机漫步机制,使得源数据包能够迅速遍历整个网络。在预编码阶段利用基于ID的估计方法进行网络全局信息估计,无需额外的全局信息估计阶段。通过设计合理的数据包选择机制使得最终编码度分布趋于理想度分布。分析和仿真结果表明,与相关文献提出的分布式存储策略相比,该方法大幅度减少了数据包传输时的随机漫步步长,同时提高了译码性能,简单易行。     

Solar and interplanetary parameters of CMEs with and without type II radio bursts

We have analyzed 101 CMEs, and their associated ICMEs and interplanetary (IP) shocks observed during the period 1997–2005. The main aim of the present work is to study the interplanetary characteristics of metric and DH type II associated CMEs such as, shock strength, IP shock speed, ICME speed, stand off distance and transit time. Among these 101 CMEs, 38 events show both metric and DH type II bursts characteristics. There are no metric and DH type II association for 52 events. While DH type II alone is found in 7 cases, metric type II alone is found in 4 events. It is found that the mean speeds of CMEs increase progressively from CMEs without type II events to CMEs associated with metric and DH type IIs as suggested by Gopalswamy et al. (2005). In addition, we found that the speeds of ICMEs and IP shocks progressively increase in the following order: events without metric and DH type IIs, events with metric alone, events with DH alone and events with both metric and DH type IIs. Similarly the Mach number is found to increase in the same order. While there is not much change in the stand-off distance among these cases, it is minimum (∼18 R_⊙) for CMEs with speed greater than 2200 km/s. The above results confirm that more energetic CMEs can produce both metric and DH type IIs for which the interplanetary parameters such as mean values of ICME speed and IP shock speed and Mach number are found to be higher.     

空间因特网与空间测控

空间因特网的建立是空间数据系统发展的必然趋势,CCSDS提出在2020年建立行星际因特网,全世界各国空间组织的技术专家们已展开对下一代空间因特网的研究。文章从空礼数据系统现状出发,分析了建立空间因特网需要解决的问题,并探讨了空间因特网的实现将对空间测控带来的影响。     

A synchrotron-based facility for the in-situ location,chemical and mineralogical characterization of ∼10 μm particles captured in aerogel

NASA’s Stardust mission collected dust from the coma of Comet Wild-2 on January 2nd, 2004, by direct capture into aerogel cells that flew through the dust coma at ∼6 km/s. Stardust collected several hundred comet particles >10 μm in size. These comet samples were delivered to Earth on January 15th, 2006. We developed a facility at the National Synchrotron Light Source at Brookhaven National Laboratory (Upton, NY, USA) for the in-situ characterization of ∼10 μm particles collected in aerogel. These analytical instruments allow us to perform extensive chemical, mineralogical, and size-frequency characterization of particles captured in aerogel. These analyses are conducted without any invasive extraction, minimizing the possibility of contamination or particle loss during preparation. This facility was used to determine the chemical composition, the oxidation state, the mineralogy and to provide an indication of the grain size of the Wild-2 particles before they were removed from the aerogel. This information provides a catalog of particle types, allowing a more reasoned allocation of the particles to subsequent investigators based on a relatively detailed knowledge of the chemical composition and mineralogy of each particle. These measurements allowed a comparison of the chemical and mineralogical properties of the Wild-2 particles with other types of extraterrestrial materials, including interplanetary dust particles and meteorites. The success of in-situ analysis for Wild 2 particles demonstrates that synchrotron-based facilities will be important for the analysis of particles collected in aerogel on future earth-orbiting satellites and spacecraft.     

On the relation of the Forbush decreases detected by ASEC monitors during the 23rd solar activity cycle with ICME parameters

To improve the physical understanding of the Forbush decreases (FD) and to explore the Space Weather drivers, we need to measure as much geospace parameter as possible, including the changing fluxes of secondary cosmic rays. At the Aragats Space Environmental Center (ASEC) are routinely measured the neutral and charged fluxes of secondary cosmic rays. Each of species has different most probable energy of primary “parent” proton/nuclei. Therefore, the energy range of the Galactic Cosmic Rays (GCR) affected by Interplanetary Coronal Mass Ejection (ICME) can be effectively estimated using data of the ASEC monitors. We presented relations of the magnitude of FD observed in different secondary particle fluxes to the most probable energy of the primary protons. We investigate the correlations between the magnitude of FD with the size, speed, density and magnetic field of the ICME. We demonstrate that the attenuation of the GCR flux incident on the Earth’s atmosphere due to passing of the ICME is dependent on the speed and size of the ICME and the magnetic field strength.     

Modeling and data analysis of a Forbush decrease

We study the Forbush decrease of the galactic cosmic ray intensity observed in 9–25 September 2005 using the experimental data and a newly developed time-dependent three dimensional modeling. We analyze neutron monitors and muon telescopes, and the interplanetary magnetic field data. We demonstrate a clear relationship between the rigidity (R) spectrum exponent (γ) of the Forbush decrease and the exponent (ν) of the power spectral density of the components of the interplanetary magnetic field in the frequency range of ∼ 10⁻⁶–10 ⁻⁵ Hz. We confirm that an inclusion of the time-dependent changes of the exponent ν makes the newly developed nonstationary three dimensional model of the Forbush decrease compatible with the experimental data. Also, we show that the changes of the rigidity spectrum exponent γ does not depend on the level of convection of the galactic cosmic rays stream by solar wind; depending on the changes of the exponent ν, i.e. on the state of the turbulence of the interplanetary magnetic field.