基于欧拉方程的机翼设计方法及应用

以Takanashi提出的三维机翼设计理论为基础，研究与发展了一个基于欧方程和“正－反迭代、余量修正原理”的机翼设计方法。用改进的无限插值方法生成绕机翼的O－O贴体网格，采用三维欧拉方程作为充动分析计算的基本方程，该设计方法已用于某无人机机翼和一个超临界机翼设计，设计结果达到了预期的目标。     

Artificial satellites orbits in 2:1 resonance: GPS constellation

In this work, the resonance problem in the artificial satellites motion is studied. The development of the geopotential includes the zonal harmonics J₂₀ and J₄₀ and the tesseral harmonics J₂₂ and J₄₂. Through an averaging procedure and successive Mathieu transformations, the order of dynamical system is reduced and the final system is solved by numerical integration. In the simplified dynamical model, three critical angles are studied. The half-width of the separatrix is calculated through a linearized model which describes the behavior of the dynamical system in a neighborhood of each critical angle. Through the resonance overlap criterion the possible regular and irregular motions are investigated by the time behavior of the semi-major axis, argument of perigee and eccentricity. The largest Lyapunov exponent is used as tool to verify the chaotic motion.     

Interplanetary Origin of Intense,Superintense and Extreme Geomagnetic Storms

We present a review on the interplanetary causes of intense geomagnetic storms (Dst≤−100 nT), that occurred during solar cycle 23 (1997–2005). It was reported that the most common interplanetary structures leading to the development of intense storms were: magnetic clouds, sheath fields, sheath fields followed by a magnetic cloud and corotating interaction regions at the leading fronts of high speed streams. However, the relative importance of each of those driving structures has been shown to vary with the solar cycle phase. Superintense storms (Dst≤−250 nT) have been also studied in more detail for solar cycle 23, confirming initial studies done about their main interplanetary causes. The storms are associated with magnetic clouds and sheath fields following interplanetary shocks, although they frequently involve consecutive and complex ICME structures. Concerning extreme storms (Dst≤−400 nT), due to the poor statistics of their occurrence during the space era, only some indications about their main interplanetary causes are known. For the most extreme events, we review the Carrington event and also discuss the distribution of historical and space era extreme events in the context of the sunspot and Gleissberg solar activity cycles, highlighting a discussion about the eventual occurrence of more Carrington-type storms.     

M. Livio, S. M. Fall and P. Madau (eds.), The Hubble Deep Field, Space Telescope Conference Series 11

The proceedings of a conference dealing with only one piece of observational activity: the deepest optical image obtained by the HST during a 150 orbit observational program. The main result, presented in several papers, is that we are now able to witness the period of galaxy formation. Very readable too is Allan Sandage's historical review, being the introductory paper to the meeting. This revised version was published online in August 2006 with corrections to the Cover Date.