Observations of the solar wind from coronal holes

The solar wind emanating from coronal holes (CH) constitutes a quasi-stationary flow whose properties change only slowly with the evolution of the hole itself. Some of the properties of the wind from coronal holes depend on whether the source is a large polar coronal hole or a small near-equatorial hole. The speed of polar CH flows is usually between 700 and 800 km/s, whereas the speed from the small equatorial CH flows is generally lower and can be <400 km/s. At 1 AU, the average particle and energy fluxes from polar CH are 2.5×10⁸ cm^–2 sec^–1 and 2.0 erg cm^–2 s^–1. This particle flux is significantly less than the 4×10⁸ cm^–2 sec^–1 observed in the slow, interstream wind, but the energy fluxes are approximately the same. Both the particle and energy fluxes from small equatorial holes are somewhat smaller than the fluxes from the large polar coronal holes.Many of the properties of the wind from coronal holes can be explained, at least qualitatively, as being the result of the effect of the large flux of outward-propagating Alfvén waves observed in CH flows. The different ion species have roughly equal thermal speeds which are also close to the Alfvén speed. The velocity of heavy ions exceeds the proton velocity by the Alfvén speed, as if the heavy ions were surfing on the waves carried by the proton fluid.The elemental composition of the CH wind is less fractionated, having a smaller enhancement of elements with low first-ionization potentials than the interstream wind, the wind from coronal mass ejections, or solar energetic particles. There is also evidence of fine-structure in the ratio of the gas and magnetic pressures which maps back to a scale size of roughly 1° at the Sun, similar to some of the fine structures in coronal holes such as plumes, macrospicules, and the supergranulation.     

Coronal electron density measurements using the near-ir [Fe XIII] emission lines

Observations made during the 1991 total solar eclipse and recent observations from NSO/Sac Peak are discussed. The ground-based density measurements will be complimentary to SOHO observations, particularly SOHO electron density measurements.Operated by the Association of Universities for Research in Astronomy, Inc. (AURA) under cooperative agreement with the National Science Foundation     

飞机平尾大轴(圆管)孔边角裂纹张开型应力强度因子的封闭解

 本文提出了一种新的工程-解析方法,导出了飞机平尾大轴孔边角裂纹应力强度因子的封闭解。这种能量释放率方法非常节省机时,可以获得大量系统的新结果。     

Evidence for a Two-Stage Acceleration Process in Large Solar Energetic Particle Events

Using high-resolution mass spectrometers on board the Advanced Composition Explorer (ACE), we surveyed the event-averaged ∼0.1–60 MeV/nuc heavy ion elemental composition in 64 large solar energetic particle (LSEP) events of cycle 23. Our results show the following: (1) The Fe/O ratio decreases with increasing energy up to ∼10 MeV/nuc in ∼92% of the events and up to ∼60 MeV/nuc in ∼64% of the events. (2) The rare isotope ³He is greatly enhanced over the corona or the solar wind values in 46% of the events. (3) The heavy ion abundances are not systematically organized by the ion’s M/Q ratio when compared with the solar wind values. (4) Heavy ion abundances from C–Fe exhibit systematic M/Q-dependent enhancements that are remarkably similar to those seen in ³He-rich SEP events and CME-driven interplanetary (IP) shock events. Taken together, these results confirm the role of shocks in energizing particles up to ∼60 MeV/nuc in the majority of large SEP events of cycle 23, but also show that the seed population is not dominated by ions originating from the ambient corona or the thermal solar wind, as previously believed. Rather, it appears that the source material for CME-associated large SEP events originates predominantly from a suprathermal population with a heavy ion enrichment pattern that is organized according to the ion’s mass-per-charge ratio. These new results indicate that current LSEP models must include the routine production of this dynamic suprathermal seed population as a critical pre-cursor to the CME shock acceleration process.     

刚体航天器最短时间姿态调整研究

在最小值原理的基础上，研究了完全刚体最短时间机动问题。由最小值原理推导出问题解的必要条件，采用修正开关时间优化算法，由遗传算法确定无耦合项时的开关特性；基于同伦算法的思想，引入松弛参数，采用模拟退火法确定开关点，对传统模拟退火法进行了改进。仿真结果表明，该方法简单可行，对实际工程有一定的参考价值。     

"引博从政"的经济学分析

运用诺贝尔经济学奖得主阿罗关于较高教育水平的甄选理论，从经济学的视角对“引博从政”现象进行分析，认为由于劳动力市场中存在不确定性和招聘方与应聘方之间信息的不对称，且招聘方获得应聘方相对准确的信息的成本较大，所以理性行为人为减少这些现象的发生，需要某种甄选手段。因此，“引博从政”就成为政府决策者在现实条件下的理性选择。     

On the Lyman α and O VI Line Profiles in Streamers and Coronal Holes

The profiles of the Lyα line at 1215.6 Å and of the O VI doublet at 1031.9 Å and 1037.6 Å in the extended solar corona have been analyzed vs. latitude and radial direction, performing observations with the Ultraviolet Coronagraph Spectrometer (UVCS) on board the ESA-NASA solar satellite SOHO (Solar and Heliospheric Observatory). The results show that these lines behave differently with latitude: the H I Ly α line has larger full width at half maximum (FWHM) values in the streamer region and narrower values towards the pole, while the FWHM of O VI lines has a minimum at the center of the streamer and slightly increases towards the polar regions. We briefly discuss the impact of the results on coronal heating theories.     

Search for Signatures of a Coronal Hole in Transition Region Lines Near Disk Center

The analysis of data taken by SUMER near disk center, where a small coronal hole is observed in EIT images, is performed. From the measurements of Doppler non-thermal velocities and intensities, we search for the diagnostics and the signature of small scale structures in the coronal hole using transition region lines. Transition region lines in the range of 7 × 10⁴ K to 2.5 × 10⁵ K have a non-thermal velocity excess of 4.0 to 5.5 km s^-1 relative to the contiguous quiet Sun. While the average intensity is lower in the coronal hole than in the quiet area, this result shows an increase of turbulence at the base of the high speed solar wind. This revised version was published online in June 2006 with corrections to the Cover Date.     

用图像处理技术对航空相机镜头分辨力的测量

介绍了一种以线阵CCD固态传感器取代读数显微镜，能自动测量和实时显示结果的航空相机镜头分辨力测量系统，论述了系统的工作原理、设计及该系统的测量误差。     

基于激光平面的高精度平面测量系统的研究

介绍了一种基于激光通过柱面透镜产生激光平面,以位置敏感器件PSD为接收器件,加上相应的硬件、软件组成的激光平面测量系统。