辐射换热条件下空间薄壁圆管结构瞬态温度场、热变形有限元分析

对航天结构中常见的辐射换热条件下的空间薄壁圆管结构，构造了一种用于非线性瞬态温度计算的傅立叶－有限单元。圆管温度沿杆长用有限元离散，沿周向分布展成三角函数。圆管温度单元每个结点包含平均温度、余弦和正弦分布温度幅三个自由度，并且在每个时间步内实现了平均温度增量与沿截面温差增量的解耦。在结构热变形分析时圆管单元节点上既承受温度轴力，又承受截面温差导致的热弯矩。采用这种单元对非线性换热条件下的复杂空间结构进行离散可以较准确地反映结构的温度场与热变形。经与前人的解析解和三维有限元结果的验证，证明该单元是可靠的。对太阳能帆板梁与空间抛物面天线的热－结构分析说明这种新单元的应用价值。     

Turbulent transition in solar surges

It has been suggested that a surge can be modelled as a jet travelling in a sheared magnetic field, and that the transition to turbulence of this MHD tearing jet can explain several key observed features. In this paper we present our preliminary results of the transition to turbulencevia secondary instabilities of the MHD tearing jet. Our results confirm that turbulent transition can decelerate the surge, with decay times which compare well with surge data. Furthermore, we find that the turbulent MHD tearing jet forms magnetic field-aligned velocity filaments similar to those often observed in the surge flow field.     

Signature of coronal holes and streamers in the interplanetary space

The properties of different solar wind streams depend on the large scale structure of the coronal magnetic field. We present average values and distributions of bulk parameters (density, velocity, temperature, mass flux, momentum, and kinetic and thermal energy, ratio of thermal and magnetic pressure, as well as the helium abundance) as observed on board the Prognoz 7 satellite in different types of the solar wind streams. Maximum mass flux is recorded in the streams emanating from the coronal streamers while maximum thermal and kinetic energy fluxes are observed in the streams from the coronal holes. The momentum fluxes are equal in both types of streams. The maximum ratio of thermal and magnetic pressure is observed in heliospheric current sheet. The helium abundance in streams from coronal holes is higher than in streams from streamers, and its dependences on density and mass flux are different in different types of the streams. Also, the dynamics of -particle velocity and temperature relative to protons in streams from coronal holes and streamers is discussed.     

Periodic or random acceleration in solar flares?

The issue whether acceleration and injection of electron beams is coherently modulated by a single quasi-periodic source, or whether the injection is driven by a stochastic process in time or (eventually fragmented) in space, is investigated by menas of a periodicity analysis of metric type III bursts.We analyze 260 continuous type III groups observed byIkarus (ETH Zurich) in the frequency range of 100–500 MHz during 359 solar flares with simultaneous 25 keV hard X-ray emission, in the years 1980–1983. Pulse periods have been measured between 0.5 and 10 s, and can be described by an exponential distribution, i.e.N(P) e ^–P/1.0s. We measure the mean periodP and its standard deviation p in each type III group, and quantify the degree of periodicity by the dimensionless parameter p/P. The representative sample of 260 type III burst groups shows a mean periodicity of p/P=0.37±0.12, while Monte-Carlo simulations of an equivalent set of truly random time series show a distinctly different value of p/P=0.93±0.26. This result suggests that the injection of electron beams is periodically modulated by a particle acceleration source which is either compact or has a global organization on a time scale of seconds.     

Coupling of the coronal he abundance to the solar wind

Models of the transition region — corona — solar wind system are investigated in order to find the coronal helium abundance and to study the role played by coronal helium in controlling the the solar wind proton flux. The thermal force on -particles in the transition region sets the flow of helium into the corona. The frictional coupling between -particles and protons and/or the electric polarization field determines the proton flux in the solar wind as well as the fate of the coronal helium content.     

面向制造的卫星零件设计系统的研究与实现

针对卫星零件的设计和加工特点,提出了一种基于特征的卫星零件面向制造的设计系统体系结构,研究了基于特征的面向制造设计系统中的零件信息模型,确定了该设计系统中可制造性评价的内容,并建立了基于知识和几何推理的可制造性评价系统,以实现面向制造的设计技术在卫星零件设计中的应用.     

太阳耀斑的行星引潮力触发

阐述了太阳潮波动力学的概况，依据实际资料的统计结果指出；行星引潮力触发耀斑的效应随耀斑级别的增大而增强；对于3级及其以上耀斑，强潮汐触发较之弱触发的耀斑产出率之比高达9.33；这个重要事实在预报地球和日地空间灾害性扰动方面，会有相当大的实际价值。     

SMESE: A French-China Joint Solar Mission

SMESE (SMall Explorer For the study of Solar Eruptions) is a Franco-Chinese Microsatellite mission. The scientific objectives of SMESE are the study of coronal mass ejections and flares. Its payload consists of three instrument packages: LYOT, DESIR and HEBS. LYOT is com-posed of a Ly-α (121.6 nm) coronagraph, a Ly-α disk imager and a far UV disk imager. DESIR is an infrared telescope working at 35μm and 150μm. HEBS is a high energy burst spectrometer working in X-rays and γ-rays covering the 10keV to 600 MeV range. SMESE will be launched around 2011, providing a unique opportunity of detecting and understanding eruptions at the maximum activity phase of the solar cycle in a wide range of energies.     

Solar particle events observed at Mars: dosimetry measurements and model calculations

During the period from March 13, 2002 to mid-September, 2002, six solar particle events (SPE) were observed by the MARIE instrument onboard the Odyssey Spacecraft in Martian Orbit. These events were observed also by the GOES 8 satellite in Earth orbit, and thus represent the first time that the same SPE have been observed at these separate locations. The characteristics of these SPE are examined, given that the active regions of the solar disc from which the event originated can usually be identified. The dose rates at Martian orbit are calculated, both for the galactic and solar components of the ionizing particle radiation environment. The dose rates due to galactic cosmic rays (GCR) agree well with the HZETRN model calculations.     

太阳风速度的源表面二维结构

以IPS观测数据为基础，在考虑了加速剖面对太阳风源位置和速度大小的影响下，探讨了1984年1745-1755Carrington周太阳风速度在源表面上的二维分布.结果显示：观测和理论结果均显示出此期间北半球太阳风速度明显高于南半球，特别是经度0一30°，300-360°N的高速流均有不同程度的从极区向南侵的现象.低速带与磁中性线有一定程度的类似即均为单峰结构.但理论和观测给出的低速带的峰值位置与磁中性线的峰值位置略有差异，而且磁中性线的报幅大于观测和理论的结果.