Variation of dayside chorus waves associated with solar wind dynamic pressure based on MMS observations

The whistler-mode chorus waves are one of the most important plasma waves in the Earth’s magnetosphere. Generally, the amplitude of whistler-mode chorus waves prefers to strengthen when the energetic fluxes of anisotropic electrons increase outside the plasmapause. This characteristic is commonly associated with the geomagnetic storms or substorms. However, the relationship between the solar wind dynamic pressure (P_sw) and the long-time variation of chorus waves during the quiet period of the geomagnetic activity still needs more detailed investigations. In this paper, based on MMS observations, we present a chorus event just observed in the inner side of magnetopause without obvious geomagnetic storms or substroms. Interestingly, during this time interval, some P_sw fluctuations were recorded. Both the amplitudes and frequencies of chorus waves changed as a response to the variation in P_sw. It proved that the enhancement of P_sw increases the energetic electrons fluxes, which provides free energies for the chorus amplification. Furthermore, the wave growth rates calculated using linear theory increases and the central frequency of the chorus waves shifts to a higher frequency when the P_sw enhancement is greater, which are also consistent well with the observations. The results provide a direct evidence that the P_sw play an important role in the long-time variation of whistler-mode chorus waves inside the magnetopause.     

Wave-Particle-Electric Field Synergetic Auroral Electron Acceleration

Space Science Reviews - We discuss afresh the problem of the auroral electron acceleration based on the controversy reports of Bryant, D. A. et al.: 1992, Phys. Rev. Lett. 68, 37, and Borovsky, J.:...     

Collision Risk Mitigation in Geostationary Orbit

The short- and long-term effects of spacecraft explosions, as a function of the end-of-life re-orbit altitude above the geostationary orbit (GEO), were analyzed in terms of their additional contribution to the debris flux in the GEO ring. The simulated debris clouds were propagated for 72yrs, taking into account all the relevant orbital perturbations.The results obtained show that 6–7 additional explosions in GEO would be sufficient, in the long term, to double the current collision risk with sizable objects in GEO. Unfortunately, even if spacecraft were to re-orbit between 300 and 500km above GEO, this would not significantly improve the situation. In fact, an altitude increase of at least 2000km would have to be adopted to reduce by one order of magnitude the long-term risk of collision among geostationary satellites and explosion fragments. The optimal debris mitigation strategy should be a compromise between the reliability and effectiveness of spacecraft end-of-life passivation, the re-orbit altitude and the acceptable debris background in the GEO ring. However, for as long as the re-orbit altitudes currently used are less than 500km above GEO, new spacecraft explosions must be avoided in order to preserve the geostationary environment over the long term.     

电子会议系统在型号产品研制中的应用

计算机技术和通信技术的结合把计算机从传统的孤立应用推进到支持群体协同工作，从而产生了计算机支持的协同工作和多媒体电子会议系统等新型应用。本文结合本单位的实际，进行了基于Sametime电子会议协同研制工作的研究，详细论述了型号研制对电子会议系统的要求及其实现。     

航天器的防污染技术

简单介绍了航天器污染的概念,污染对航天器的损害,航天器污染研究的重要性,以及国内外航天器防污染研究概况。着重介绍真空热试验中的污染控制方法。引入航天器自污染的概念,介绍消除航天器自污染的有效办法是真空烘烤。     

网络最大流与最小割集的矩阵算法

本文给出了解决运输问题为中心的一类特殊的线性规划问题的新的、简便的算法。网络最大流与最小割集的矩阵算法,不仅能解决许多这类问题,而且能使最小费用流、分配问题和运输问题容易通过计算机来实现。     

丁羟推进剂拉伸断裂行为的扫描电镜研究

利用扫描电镜及附属微型动态拉伸装置实验手段，对丁羟基复合固体推进剂进行了断口微观形貌观察和电镜微型拉伸试件在应变状上的断裂行为分析。结果表明，从推进剂拉伸力学行为的微观结构变化以预示其宏 同力学性能，改善丁羟推进剂粘合剂与固体颗粒之间的界面性质，是固体推进剂力学性能的一个重要方向。     

A first step towards proton flux forecasting

We present a preliminary version of a potential tool for real time proton flux prediction which provides proton flux profiles and cumulative fluence profiles at 0.5 and 2 MeV of solar energetic particle events, from their onset up to the arrival of the interplanetary shock at the spacecraft position (located at 1 or 0.4 AU). Based on the proton transportation model by Lario et al. [Lario, D., Sanahuja, B., Heras, A.M. Energetic particle events: efficiency of interplanetary shocks as 50 keV E < 100 MeV proton accelerators. Astrophys. J. 509, 415–434, 1998] and the magnetohydrodynamic shock propagation model of Wu et al. [Wu, S.T., Dryer, M., Han, S.M. Non-planar MHD model for solar flare-generated disturbances in the Heliospheric equatorial plane. Sol. Phys. 84, 395–418, 1983], we have generated a database containing “synthetic” profiles of the proton fluxes and cumulative fluences of 384 solar energetic particle events. We are currently validating the applicability of this code for space weather forecasting by comparing the resulting “synthetic” flux profiles with those of several real events.     

顺序函数法求解二维非稳态热传导逆问题

基于有限控制体积法对二维非稳态热传导问题的数值模拟，导出了处理二维非稳态热传导逆问题的顺序函数法，并用该方法来对一典型的圆环域边界条件反演问题进行了反演计算，结果表明，顺序函数法是求解二维非稳态热传导逆问题的有效方法，当测量噪声比较小时，顺序函数法能得出较高精度的反演结果；当测量噪声增大时，反演结果仍能较好地再现出精确解在空间和时间方向上的变化趋势，具有一定精度。     

等价差分格式在三维复杂流场数值模拟中的应用

结合数值Riemann不变量和通量限制器（FluxLimiter）的概念，将基于Chakravarthy和Osher半离散差分格式的等价差分格式应用于三维复杂流场计算，应用时间相关法和全流场捕捉技术，获得了Ma＝10，a＝10°状态下球头绕流结果，壁面压力分布与Rusanov的计算结果相符合，在此基础上细致地刻画了在Ma＝7，a＝20°状态下绕流带座能飞船的复杂流场。