区域观察小卫星星座重构方法研究

在对地观测任务中，经过优化设计的卫星星座通常具有较强的适应能力。但是，当星座中某颗卫星失效或地面需求发生变化时，就需要进行星座重构，以恢复或增强对部分地区的观察能力。提出了小卫星区域观察组网的方法，重点探讨了在应急情况下区域观察小卫星星座的重构问题，研究了节省能量的卫星轨道机动方法，特别提出了保持轨道属性和星座基本构形的预置量机动方法，分析了应急机动星座重构的几种情况，给出了每种情况的星座重构策略。     

一种分布式卫星构形变换路径规划方法

在一种分层控制体系结构下研究了分布式卫星系统的构形变换问题。以控制量的二次型性能指标作为构形变换控制的优化指标,线性离散模型下的构形变换动力学约束作为基本约束,将构形变换的路径规划问题作为一个二次规划问题求解,并给出了数值仿真的算例。在单个绕飞星构形变换规划算法的基础上,提出了一种整体优化方法,使构形变换过程中整体能量最优,依此作为构形变换的顶层规划方法,并给出了仿真结果。     

J2摄动作用下近地轨道卫星编队构形长期演化机理分析

研究近地轨道卫星编队构形在引力摄动作用下的长期演化机理。把用转移矩阵法得出的相对运动分析解表达成一般轨道根数形式，为研究摄动影响而进一步表达成无奇点轨道根数形式；根据各轨道根数的J2摄动解分别研究编队构形在轨道坐标系三个方向上的振幅与相位的长期变化情况，揭示了构形引力摄动的长期演化机理；给出编队构形的摄动表达式，并以仿真实例验证其可信性；最后给出构形长期引力摄动的相关结论，并对编队构形设计提出建议，这将为研究编队构形的规划技术带来方便。     

基于电磁力与力矩的航天器运动控制的研究进展

电磁力与力矩是一种非接触式的相互作用力与力矩.将通电线圈或磁铁放在磁场中会受到电磁力与力矩的作用.多个通电线圈或磁铁相互作用时，在彼此构成的磁场中也会受到电磁力与力矩的作用.作为一种非接触的力与力矩，电磁力与力矩在航天器的姿态与相对位置控制系统中已有了广泛和深入的应用.本文主要介绍近年来由航天器上电磁装置受到地磁场作用产生电磁力矩在姿态控制中的应用，和带有电磁机构的多航天器间相互作用控制多航天器间相对位姿的应用等.     

当前高校青年教师思想政治教育面临的问题及对策探析

受当前全球化浪潮的强势冲击和市场经济的负面影响,高校青年教师的思想政治教育面临一系列挑战,直接影响了高校思想政治教育的效果。要摆脱困境,必须坚持以人为本的教育理念,重视师德建设、创新教育方法、健全激励机制,切实增强思想政治教育的吸引力、说服力、影响力和感染力。     

协同小卫星系统和服务

文章提出一个新概念:协同小卫星系统和服务(应用),简称5S(Synergic Small Satellites Systems and Services)。其目的是积极研究和开发多颗小卫星联合协同工作,开创在各领域新的应用。文中首先论述5S的概念与内涵;其次研究小卫星星座和编队飞行性能特点与系统设计;最后介绍近几年来协同小卫星系统的4个创新应用示例。     

Formation of the Outer Planets

Models of the origins of gas giant planets and ‘ice’ giant planets are discussed and related to formation theories of both smaller objects (terrestrial planets) and larger bodies (stars). The most detailed models of planetary formation are based upon observations of our own Solar System, of young stars and their environments, and of extrasolar planets. Stars form from the collapse, and sometimes fragmentation, of molecular cloud cores. Terrestrial planets are formed within disks around young stars via the accumulation of small dust grains into larger and larger bodies until the planetary orbits become well enough separated that the configuration is stable for the lifetime of the system. Uranus and Neptune almost certainly formed via a bottom-up (terrestrial planet-like) mechanism; such a mechanism is also the most likely origin scenario for Saturn and Jupiter.     

The Formation Of The First Stars In The Universe

In this review, I survey our current understanding of how the very first stars in the universe formed, with a focus on three main areas of interest: the formation of the first protogalaxies and the cooling of gas within them, the nature and extent of fragmentation within the cool gas, and the physics – in particular the interplay between protostellar accretion and protostellar feedback – that serves to determine the final stellar mass. In each of these areas, I have attempted to show how our thinking has developed over recent years, aided in large part by the increasing ease with which we can now perform detailed numerical simulations of primordial star formation. I have also tried to indicate the areas where our understanding remains incomplete, and to identify some of the most important unsolved problems.     

Hypergravity suppresses bone resorption in ovariectomized rats

The effects of gravity on bone metabolism are unclear, and little has been reported about the effects of hypergravity on the mature skeleton. Since low gravity has been shown to decrease bone volume, we hypothesized that hypergravity increases bone volume. To clarify this hypothesis, adult female rats were ovariectomized and exposed to hypergravity (2.9G) using a centrifugation system. The rats were killed 28 days after the start of loading, and the distal femoral metaphysis of the rats was studied. Bone architecture was assessed by micro-computed tomography (micro-CT) and bone mineral density was measured using peripheral quantitative CT (pQCT). Hypergravity increased the trabecular bone volume of ovariectomized rats. Histomorphometric analyses revealed that hypergravity suppressed both bone formation and resorption and increased bone volume in ovariectomized rats.     

Optimal satellite formation reconfiguration actuated by inter-satellite electromagnetic forces

The inter-satellite electromagnetic forces generated by the magnetic dipoles on neighboring satellites provide an attractive control actuation alternative for satellite formation flight due to the prominent advantages of no propellant consumption or plume contamination. However, the internal force nature as well as the inherent high nonlinearity and coupling of electromagnetic forces bring unique dynamic characteristics and challenges. This paper investigates the nonlinear translational dynamics, trajectory planning and control of formation reconfiguration actuated by inter-satellite electromagnetic forces. The nonlinear translational dynamic model is derived by utilizing analytical mechanics theory; and analysis on the dynamic characteristics is put forward. Optimal reconfiguration trajectories of electromagnetic force actuated formation are studied by applying optimal control theory and the Gauss pseudospectral method. Considering the high nonlinearity and uncertainty in the dynamic model, an inner-and-outer loop combined control strategy based on feedback linearization theory and adaptive terminal sliding mode control is proposed with finite-time convergence capability and good robust performance. Theoretical analysis and numerical simulation results are presented to validate the feasibility of the proposed translational model, reconfiguration trajectory optimization approach and control strategy.