天线罩外形形线对天线罩性能的影响

比较和分析了不同天线平外形形线在不同长细比情况下对天线罩的电气性能和气动特性的影响。分析认为，在设计天线罩时，应根据导弹和天线罩的综合性能要求进行综合处理。     

相应于一类幂零李代数的顶点代数结构

顶点代数和顶点算子代数在物理学领域有着广泛的应用,因此对其研究也有很大的实际意义。主要从有限维幂零李代数g出发,给出了g带有非退化对称不变双线性函数的条件,并构造了相应于g的一个代数结构,从同构的意义上证明了其满足顶点代数的条件,从而给出了一个新的顶点代数结构。     

卫星天线反射面板热形变面形误差检测方法

为实现航天卫星天线面板热形变面形误差高精度检测,提出利用三坐标测量系统搭载高精度激光位移传感器,对检测对象进行扫描测量;并通过对其系统误差来源进行分析、公差合理分配及误差控制,提出对测量系统进行整体优化,以满足所提出检测精度要求。为验证所提出方法的可行性,搭建测量系统,对标准试件的测量数据进行面形拟合,获得测量偏差优于±4.22μm/m2;分别制作常规铝板及光滑铝板作为测试对象,在其背部黏贴加热板的加热方式,以模拟卫星面板在实际工作环境中发生热形变。采用提出的方法对其进行了热形变面形误差检测实验,检测结果验证了所提出方法的可行性。     

Stability and shape analysis of relative equilibrium for three-spacecraft electromagnetic formation

The invariant shapes for close formation flying with inter-craft electromagnetic force ensure several potential space applications. However, the 6-DOF relative equilibrium problem has not been systematically investigated. This paper mainly analyzes the invariant shapes of relative equilibrium for the three-spacecraft electromagnetic formation, and studies the families of invariant shape solutions with real and constant magnetic moments as well as their linear stability. The problem is examined based on the full nonlinear coupled dynamic models for collinear and general triangular configurations. The relative equilibrium conditions are analyzed to determine whether an invariant shape do exist, and the corresponding families of invariant shape solutions are identified for static and spinning configurations respectively. Finally, the linear stability of such invariant shapes is numerically discussed, which have shown that most invariant shapes are unstable and controllable.     

Polarization model for discrimination of broad and needle shaped leaves and estimation of LAI using polarization measurements

Method for estimation of Leaf Area Index (LAI) based on polarized radiance measurements is proposed. Leaf angle dependency on LAI estimation can be taken into account by considering polarization characteristics of leaves. Effectiveness of the proposed method is confirmed with the polarized radiance from tealeaves and the other needle leaf types of grasses. Convenient way to monitor quality and amount of leaves with network camera with polarization film is also proposed.     

基于三维有限元的火箭模态振型斜率预示方法研究

振型斜率火箭是姿控系统设计的重要参数,对飞行任务的可靠性与安全性有着至关重要的作用。依据全箭动特性的测量原理及参数定义,结合三维有限元建模方法和模型修正技术,全面考虑了速率陀螺、惯组安装位置处的局部刚度对振型和振型斜率的影响,建立了基于局部细节精细化建模的全箭模态振型斜率预示方法,并总结了3种不同的振型斜率提取方法,提高了振型斜率的预示精度。同时提供了三维模型振型一维化的方法,解决了使用三维有限元模型计算弹性运动方程式系数的难题。     

Shape control of spacecraft formation using a virtual spring-damper mesh

This paper derives a distance-based formation control method to maintain the desired formation shape for spacecraft in a gravitational potential field. The method is an analogy of a vir-tual spring-damper mesh. Spacecraft are connected virtually by spring-damper pairs. Convergence analysis is performed using the energy method. Approximate expressions for the distance errors and control accelerations at steady state are derived by using algebraic graph representations and results of graph rigidity. Analytical results indicate that if the underlying graph of the mesh is rigid, the convergence to a static shape is assured, and higher formation control precision can be achieved by increasing the elastic coefficient without increasing the control accelerations. A numerical exam-ple of spacecraft formation in low Earth orbit confirms the theoretical analysis and shows that the desired formation shape can be well achieved using the presented method, whereas the orientation of the formation can be kept pointing to the center of the Earth by the gravity gradient. The method is decentralized, and uses only relative measurement information. Constructing a distributed virtual structure in space can be the general application area. The proposed method can serve as an active shape control law for the spacecraft formations using propellantless internal forces.     

系留气球囊体外形优化研究

利用基于约束的Kanikdale修正算法,以及一套用于确定尾翼尺寸和系留缆绳外形的方法,并借助基于GA的GADO优化器,对系留气球囊体形状进行了优化研究。结果表明,通过多材料组合方式生成的囊体,其有效载重能力能够提升6.5%左右。     

直纹二次曲面的实时成像算法

基于二次曲面的等灰度实时成像原理，将二次曲面分成直纹面和非直纹面两类，针对直纹曲面等灰度线的特点，提出了一种非常简洁、有效的二次直纹曲面的实时成像算法。该算法不仅大大提高了这类曲面的成像速度，而且简化了它与其他二次曲面图元拼接形体的实时成像处理过程。