在不同地形条件下的地形辅助导航系统定位精度评估

如何选择合适的地形是卡尔曼连续修正的地形辅助导航系统在实际应用中遇到的难题。本文首先建立系统仿真模型，然后利用ＡＲＣ／ＩＮＦＯ地理信息系统软件进行地形分析。在此基础上，通过大量的计算机仿真试验，对卡尔曼连续修正的地形辅助导航系统在不同地形条件下的定位精度进行了评估。评估结果为系统在实际应用中的地形选择提供了依据。     

空心圆柱试样试验仪及其递推辨识建模

介绍了空心圆柱试样试验仪的总体结构及加载原理，以及在连续加载试验的条件下系统定量分析所必须解决的系统建模等问题的重要性，简述了采用递推增广最小二乘法对随机、时变和非线性系统实现在线、实时递推辨识建模的原理和以ＩＢＭ－ＰＣ／ＸＴ计算机为核心实现计算机辅助递推辨识的原理和方法、递推辨识系统的硬件构成以及为提高递推辨识速度和精度在软件过程中采用的处理技术，讨论了该递推辨识系统在空心圆柱试样试验仪控制试验中的应用及其实际效果。     

Design and analysis of a direct transfer trajectory from a near rectilinear halo orbit to a low lunar orbit

A near rectilinear halo orbit (NRHO) is regarded as a potential orbit for a future deep space station that can effectively support sustainable crewed lunar exploration missions. In this paper, the L₂ southern NRHOs are selected as the research object, and a direct transfer trajectory from an NRHO to a low lunar orbit (LLO) is designed and analyzed. First, based on the circular restricted three-body problem, the characteristics of NRHOs are discussed including geometric behaviour, stability and synodic resonance. Second, optimal direct transfer trajectories are obtained by combining a local gradient optimization with a numerical continuation strategy. A reachable domain calculation model is established. Finally, simulations are carried out to verify the feasibility of the trajectory design method. The relationship between the velocity change and the reachable domain is further analysed through simulation calculations.     

Venus transfer design by combining invariant manifolds and low-thrust arcs

The design of interplanetary trajectories based on patched circular restricted three body models is gradually becoming a valuable alternative to the classical patched conic approach. The main advantage offered by such a model is the possibility to exploit the manifold dynamics to move naturally far from or toward a body. Generally, propulsive maneuvers are required to match these structures. Low-thrust arcs offer the possibility to have a significant propellant mass reduction when moving from manifold to manifold. The aim of this paper is to present a methodology to design low-thrust trajectories between two planetary orbits connecting the manifolds of two circular three body systems. The approach is based on a grid search on the main parameters governing the solution to identify those trajectories moving within the manifold images on given Poincarè sections. The value of the Jacoby constant of the target libration point periodic orbit is chosen as stop condition for the thrusting phases. Ballistic arcs follow up to the proper Poincarè section intersection. A grid search for an Earth to Venus transfer is presented as test case.     

改变微带天线基板形状实现圆极化

实现微带贴片天线圆极化的方法中,传统方法主要是设计适当的金属贴片形状和选择适当的馈电方式,而一种新思路即设计适当的介质基板形状,在某些使用环境中可以提供较大的方便。通过计算发现新思路有其可行性和工程价值,在某些方面有其独特的优势。     

卫星承力筒复合材料结构的优化设计

应用JIFEX软件对大型通信卫星主承力结构－－中心承力筒的复合材料结构进行优化设计。在优化设计中考虑了固有频率和屈曲稳定性的约束条件，使用了多种类型的设计变量，对蜂窝夹芯材料采用了一种离散材料变量连续化处理方法。进行了多种方案的优化设计和比较，为承力筒结构研制设计提出了指导性结论。     

某型飞机护板作动筒自动开锁故障分析及改进

针对某型飞机护板在飞行中自动打开的故障,对护板收放作动筒工作原理、结构组成进行了研究,在开锁试验验证和故障件分解检查后,确定了作动筒自动开锁的原因是由于弹簧力过小,使得作动筒开锁压力小于瞬时回油压力所致.通过改进作动筒内部零件弹簧的安装方式,增大了开锁压力,提高了开锁压力的稳定性,排除了故障,为飞机飞行安全提供了保障.     

小型二冲程航空发动机燃烧循环变动研究

利用峰值压力、最大压力上升率、燃烧百分率以及它们各自所对应的曲轴转角和相空间重构投影法评价小型二冲程航空发动机的燃烧循环变动.通过比较,认为燃烧百分率所对应的曲轴转角能更好地表征发动机的燃烧循环变动.针对发动机在中速和不同负荷条件下的燃烧循环变动分析,结果表明随负荷的加大,缸内燃烧的循环变动会变小,认为是负荷加大,气体...     

双翼金属圆柱体散射场的整体计算

本文利用keller的几何绕射理论（GTD）推求出双翼金属圆柱体散射场高频快收敛整体解，弥补了传统分离解（把系统分解为一个金属圆柱和两个金属半平面，分别求解再简单迭加）的不足之处，最后，给出了整体解和分离解的散射电场的模值数值计算结果。