UDu~T分解滤波算法及其应用

本文介绍UDU~T 分解滤波算法;用工程师容易理解的方法重新推导时间修正和量测修正滤波公式,并给出标准通用的UDU~T 分解滤波子程序。本算法子程序已实际用于工程估计器中。本算法具有高的数字稳定性。作为UDU~T 分解滤波算法理论和工程应用之间桥梁的本通用标准子程序具有良好性能,使用方便,极易推广应用。     

绳系卫星部署阶段的动力学分析

绳系卫星系统部署阶段末时刻状态决定着其编队飞行的初始状态，为了研究不同因素对绳系卫星系统部署阶段运动的影响，本文建立了一种简单的平面哑铃模型，将系绳视作有阻尼的弹簧，两个卫星视作刚体，考虑重力梯度力矩。通过仿真，发现系绳释放的速度和副星推力是影响绳系卫星系统部署阶段稳定性的主要因素。     

基于拉盖尔函数的卫星姿态预测控制方法

针对卫星在空间站中进行绕飞检测时的姿态控制问题，考虑卫星的姿态轴需要躲避禁飞区域并指向期望位置，提出了一种基于拉盖尔函数的模型预测控制方法，实现了对卫星姿态轴的控制。在模型预测控制方法的基础上，通过拉盖尔函数，将优化多个控制输入转换为优化少数的拉盖尔系数，建立了拉盖尔模型预测的控制策略，改善了传统的模型预测控制方法计算效率差的问题，减少了优化时间。采用卫星在空间站中绕飞的模型进行数值仿真验证，结果表明该方法能够使卫星的姿态轴躲避禁飞区并到达指定位置。与传统方法相比，这种基于拉盖尔函数的模型预测控制策略能够提高优化效率，减少计算时间。     

Solar Models with Non-Standard Chemical Composition

The OPAL monochromatic opacity tables are used to evaluate the impact of a non-standard chemical composition on solar models. A calibrated solar model with consistent diffusion including the effect of radiative forces and ionization on drift velocities is presented. It is shown that surface abundances are predicted to change slightly more than in traditional solar models where these refinements are not included. All elements included in the model settle at similar rates which is reflected in the relative variation in surface abundances ranging from 7.5% for calcium to 8.8% for argon. The structural difference between the consistent model and the traditional model is small, with a maximum effect of 0.3% for the isothermal sound speed at the base of the convection zone. The settling of CNO is only marginally affected. Opacity profiles have also been calculated with varying abundances for volatile elements, for which the abundances are poorly known, and other selected elements. It is shown that if one allows a 10% variation of these elements individually one can expect a peak Rosseland mean opacity variation of 3% for oxygen, a little less 2% for Si and Ne, and around 1% for Mg and S in the radiative zone. Other light metals and volatile elements have no significant impact on the opacity. This revised version was published online in June 2006 with corrections to the Cover Date.     

Propagation and interaction of interplanetary transient disturbances. Numerical simulations

We study the heliocentric evolution of ICME-like disturbances and their associated transient forward shocks (TFSs) propagating in the interplanetary (IP) medium comparing the solutions of a hydrodynamic (HD) and magnetohydrodynamic (MHD) models using the ZEUS-3D code [Stone, J.M., Norman, M.L., 1992. Zeus-2d: a radiation magnetohydrodynamics code for astrophysical flows in two space dimensions. i – the hydrodynamic algorithms and tests. Astrophysical Journal Supplement Series 80, 753–790]. The simulations show that when a fast ICME and its associated IP shock propagate in the inner heliosphere they have an initial phase of about quasi-constant propagation speed (small deceleration) followed, after a critical distance (deflection point), by an exponential deceleration. By combining white light coronograph and interplanetary scintillation (IPS) measurements of ICMEs propagating within 1 AU [Manoharan, P.K., 2005. Evolution of coronal mass ejections in the inner heliosphere: a study using white-light and scintillation images. Solar Physics 235 (1–2), 345–368], such a critical distance and deceleration has already been inferred observationally. In addition, we also address the interaction between two ICME-like disturbances: a fast ICME 2 overtaking a previously launched slower ICME 1. After interaction, the leading ICME 1 accelerates and the tracking ICME 2 decelerates and both ICMEs tend to arrive at 1 AU having similar speeds. The 2-D HD and MHD models show similar qualitative results for the evolution and interaction of these disturbances in the IP medium.     

Coronal radio-sounding detection of a CME during the 1997 Galileo solar conjunction

Frequency fluctuations of the Galileo S-band radio signal were recorded nearly continuously during the spacecraft’s solar conjunction from December 1996 to February 1997. A strong propagating disturbance, most probably associated with a coronal mass ejection (CME), was detected on 7 February when the radio ray path proximate point was on the west solar limb at about 54 solar radii from the Sun. The CME passage through the line of sight is characterized by a significant increase in the fluctuation intensity of the recorded frequency and by an increase in the plasma speed from about 234 km s⁻¹ up to about 755 km s⁻¹. These velocity estimates are obtained from a correlation analysis of frequency fluctuations recorded simultaneously at two widely-separated ground stations. The density turbulence power spectrum is found to steepen behind the CME front. The Galileo radio-sounding data are compared with SOHO/LASCO observations of the CME in the corona and with WIND spacecraft data near the Earth’s orbit.     

Interplanetary Physics Research in China:2006—2008

This brief report summarized the latest advances of the interplanetary physics research in China during the period of 2006—2007,made independently by Chinese space physicists and through international collaboration.The report covers all aspects of the interplanetary physics,including theoretical studies,numerical simulation and data analysis.     

自然通风和蒸发冷却在新疆建筑应用的数值分析

为了使新疆和田地区夏季在经济性合理前提下使室内通风环境满足人体热舒适要求。利用蒸发冷却技术将室外空气处理后送入室内，通过数值模拟分析得出在夏季室内负荷最大时刻采用机械辅助式自然通风，使得室温能够雏持在26-8℃，风速为0．6m/s，基本满足人体热舒适要求。在室外温度适宜的过渡季节采用Trombe墙和太阳能烟囱复合的自然通风系统，建筑太阳能烟囱的经济高度为10m。     

增升状态下的全机位流数值模拟

研究了势流理论下的全机增升装置复杂外形气动力数值计算方法,该方法以低阶面元法为基础,具有计算量小、速度快的优点.复杂流动的粘性效应主要通过附面层粘性修正技术加以体现.采用该方法对某增升装置翼身组合体外形压力分布特性进行计算,并和风洞实验数据相比较,验证了方法的正确性和实用性.在此基础上对某型飞机真实复杂外形的压力分布特性进行了计算,为复杂外形飞行器增升装置的初步设计、方案选型与评估提供了非常理想的工程技术手段.     

国际空间太阳能电站的技术进展

综述了当前国际空间太阳能电站技术的研究进展与发展趋势。重点介绍了空间太阳能电站系统方案新构思“太阳塔”和“太阳盘”的特点；介绍了空间太阳能电站的主要相关技术———无线电能传输技术、太阳能转换技术和空间运输技术等的发展趋势；最后简要介绍了月球电站的进展情况。