采用单轴双太阳帆板空间站的一种姿态定向模式

采用单轴双帆板供电和单框架控制力矩陀螺(SGCMG)作为执行机构的倾斜轨道空间站,当太阳方向与轨道面夹角较大时,帆板的光照条件不易保证,为此本文针对这种类型的空间站设计了一种姿态定向模式以保证帆板的光照条件,并通过在阴影区姿态机动,利用重力梯度力矩对SGCMG进行卸载。仿真结果表明,该姿态定向模式满足太阳帆板的光照条件,重力梯度力矩卸载方法保证了SGCMG中的角动量不超出给定的范围。     

基于真实场景的SAR回波模拟方法研究

SAR原始回波模拟在系统设计及成像算法验证等方面具有重要的理论及工程实践意义。文中在分析并建立合成孔径雷达回波信号数学模型的基础上,研究一种基于真实场景的SAR回波模拟方法。该方法利用SAR真实场景图像的灰度信息近似求得场景后向散射系数,根据雷达脉冲工作流程生成回波数据,具有实现简单、计算量小、回波模拟结果精确等优点。通过点目标、面目标和真实场景回波的仿真实验,从回波数据的统计特性以及图像级角度验证了其可行性。     

Tunable Electromagnetic Cloaking by External Field

Electromagnetic cloaking based on the scattering cancellation method have been reviewed. The possibility of designing the tunable electromagnetic cloaking is analytically suggested with a single cloak composed of homoge- neous materials, including semiconductor, superconductor, ferrite and ferroelectrics by using Mie scattering theo- ry. The simulated results demonstrate that the cloaks with these homogeneous materials can drastically reduce the total scattering cross sections of the cloaked system by using the finite element method. These cloaking frequencies can be controlled by external field through tuning the permittivity or permeability of these materials by the applied field, such as temperature, magnetic field and electric field. These may provide some potential ways to design tunable cloaking with considerable flexibility.     

农村政治困境：贿选、宗派与组织悬浮

由于我国基层政治监管制度不完善,同时受传统宗族势力与派性影响,当前我国农村的一些地区出现了贿选、腐败、多数人暴政、地下宗教活动泛滥、村委组织悬浮等乱象.破解中国农村政治困境,需健全村干部权利监督机制、倚重合作组织、广泛听取民意并加强村干部监管与培训.     

Analysis of the solar sail deformation based on the point cloud method

The deformation of the solar-sail membrane is an important factor for causing inaccuracies in the solar-sail missions. This paper describes the solar sail under deformation by using a new modelling technique based on point cloud and triangular mesh generation. Two types of deformation, stemming from wrinkling and billowing, are modelled. The changes in the solar radiation pressure force and the moment caused by deformation are calculated and compared to the ideal non-deformed case. The heliocentric spiral trajectory and the orbital angular momentum reversal trajectory are taken as examples to quantify the influence of the deformation from an orbit point of view. Additionally, point cloud simplification, based on the normal vector and bounding box, is utilized to simplify the original deformed-sail model. It involves a reasonable reduction and renewal of the points in the model considering the variation of surface curvature. The simplification and its modelling accuracy are numerically investigated as well as computational efficiency.     

“火星”来信了

截止到2011年1月5日,"火星500"模拟试验已进行了216天,本刊通过俄罗斯联邦航天局,以电子邮件形式采访了这6名志愿者,下面是他们的精彩回信。1."火星500"共有多少项试验?中国参加了哪一些?▲"火星500"实验项目数量有100项以上,其中包括生理学考察,心理学和心理生理学考察,生物化学、免疫学和生物学考察,微生物学和卫生保健学考察,技术操作实验等。中国的王跃参加了所有的试验。     

某型飞机油箱电缆插座接头密封技术

针对某型飞机油箱插座接头原使用S1125胶出现绝缘电阻下降问题，本文对电缆插座接头密封用胶进行选型，采取了六种密封剂选型方案，通过性能试验及灌注施工简捷两方面的对比，XM-22C密封剂用于插座接头的密封最为理想，满足了电缆对绝缘电阻设计的要求。     

空战攻防对策力学准则的推广

对空战攻防对策力学准则进行了推广研究。导出考虑导弹杀伤半径不为零时的“圆捕获”的界栅方程，该方程表明“点捕获”界栅方程是“圆捕获”界栅方程的特例，给出了捕获区，逃逸区和界栅几何图形，该图形描述了界栅与视线距，视线变化率，视线角速度之间的关系；分析了导弹杀伤半径，导弹和目标机动能力的差值对导弹和目标空战效果的影响。     

高超声速飞行器抗饱和鲁棒自适应切换控制

针对高超声速飞行器执行机构饱和的控制器设计问题,提出一种多回路抗饱和鲁棒自适应切换控制方法. 首先针对高超声速飞行器的运动模态在频率上表现出显著的分离特性,将状态变量分开不同的回路设计;然后对受执行机构饱和影响明显的状态设计参考切换系统,从而降低模型和控制器参数设计的复杂性,将一系列可能导致执行机构饱和的事件视作切换信号,选定参考切换模型及鲁棒自适应控制器,保证控制输入不达到饱和状态,并通过多李亚普诺夫函数方法和线性矩阵不等式分析了控制器的稳定性. 仿真结果表明了控制方案的有效性,在存在执行机构失效故障和干扰的情况下,系统状态可良好的跟踪参考状态且控制输入小于执行机构限幅.