Study on Satellite-to-ground Laser Communications with Existence of Atmosphere

The laser beam used to establish a communication channel between satellite and ground segments has a small divergence angle and a tiny spot on the Earth’s surface, which may lead to the fail of the system. So it’s important to study the deflection of laser beam by the Earth’s atmosphere and find a way to calibrate this error. Both theoretical analysis and real data processing method are used to obtain the mathematical model for divergence angle of laser communication beam and its correction function. Then the model has been applied to the data, which was used to describe the atmosphere state by traditional ground segments to obtain the critical elevation angle. According to the results of calculation, our conclusion will be that the correction should be done when the critical elevation happens.      

均布压力作用各向异性矩形薄板大挠度问题

基于冯·卡门模型，选择中心挠度为摄动参数，利用摄动方法将正交异性矩形薄板大挠问题的非线性偏微分方程组逐级线性化，导出了各级摄动对应的几个线性偏微分方程组，然后再借助变分法求解，得到了均布载荷作用下正交异性矩形薄板的载荷-挠度曲线。     

基于多体系统动力学的旋翼桨叶响应计算方法

在中等变形梁的基础上引入增广转换矩阵,为解决桨叶动能项推导编程计算较为复杂的问题,建立了一种新的递推计算方法。该方法在原有的转换矩阵基础上进行了增广,建立了相邻运动坐标系间动能项引起的质量、阻尼、刚度和广义力递推计算方法。以法国SA349/2小羚羊直升机的试飞测试数据为依据,验证了方法的有效性。     

非线性薄梁结构对冲击波载荷的大挠度响应分析

采用大挠度弹性梁理论和中心差分法分析计算了非线性薄梁结构对冲击波载荷作用的大挠度响应，模型包括了纵向变形和横向变形之间的弹性耦合。算例给出了拉－弯耦合、拉／弯刚度比和冲击波冲量对挠度响应的影响。     

基于微型涡喷发动机热喷流的无源流体推力矢量喷管的控制规律

流体推力矢量喷管型面固定、活动部件少、结构重量轻，能够为高机动飞行器提供有效的飞行控制手段，但无源流体推力矢量喷管热喷流的偏转控制规律尚未完全掌握。为了推进无源流体推力矢量技术的实用化，本文设计研制了适用于微型涡喷发动机的耐高温喷管模型，对该喷管在微型涡喷发动机热喷流状态下的控制规律进行研究。利用非接触光学显示和测量手段——红外热成像拍摄和粒子图像测速（PIV）技术对主射流流动特性进行研究，获得流动矢量角随二次流控制阀门闭合度变化的控制规律；利用六分量盒式天平测力实验研究无源流体推力矢量喷管的力学特性，获得推力矢量角随二次流控制阀门闭合度变化的控制规律。研究结果表明：该构型喷管在微型涡喷发动机热喷流下主射流连续可控偏转，最大流动矢量角为-12.3°/12.3°，最大推力矢量角为-12.9°/12.8°，控制规律接近线性，不存在主射流偏转突跳问题。     

Experimental study on plasma jet deflection and energy extraction with MHD control

This paper presents an integrated research scheme for vector deflection and energy extraction in a gas plasma jet under Magneto-Hydrodynamic (MHD) control. A MHD-controlled thrust-vector test rig was used to conduct the experimental research. A gas plasma was obtained by injecting ionization seeds of Cs₂CO₃ into the combustion chamber via artificially forced ionization. The effects of the gas temperature and ionization seed mass fraction on the plasma jet deflection and energy extraction were experimentally verified under an applied magnetic field. The experimental results were analyzed theoretically. The results showed that the deflection amplitude of the gas plasma jet and the extracted voltage signal intensity increased with increasing gas temperature and the ionization seed mass fraction. The extracted dynamic voltage signals proved that the ionization seeds of Cs₂CO₃ induced gas ionization at 1173 K. The experiment verified that it is feasible to simultaneously achieve jet deflection and extract energy under the action of an external magnetic field.     

矩形橡胶复合材料层合板的大变形研究

本文应用Ｋｉｒｃｈｈｏｆｆ假设和ＶｏｎＫａｒｍａｎ理论对正交各向异性的矩形橡胶复合材料层合板进行了几何非线性分析。与线性结果相比，大变形理论所得结果更具准确性。     

Rosetta Asteroid Targets: 2867 Steins and 21 Lutetia

In preparation for the flyby of the Rosetta spacecraft, the state of the knowledge of 21 Lutetia and 2867 Steins obtained by ground based observations is reported. Preliminary determination of shape and/or size, rotational properties and taxonomic types are presented for both asteroids. The dusty environment of the targets has been studied in order to help in defining safe fly-by trajectories without the risk of damaging collisions. The expected science return from the asteroid fly-by is also discussed.     

A sample collector for robotic sample return missions III: Impact survivability studies

Laboratory impact tests have been performed on experimental versions of a proposed robotic sample collector for extraterrestrial samples. The collector consists of a retractable aluminum ring containing an impregnable silicone compound that is pressed into the surface of the body to be sampled. As part of a comprehensive program to evaluate this idea, we have performed tests to determine if the samples embedded in the collector medium can survive the impact forces experienced during direct reentry, such as that of the recent Genesis sample return mission. For the present study, samples of sand, rock, glass, and chalk were subjected to decelerations of 1440–2880 g using drop tests. We found that even the most fragile samples, chosen to be representative of a wide range of the types of materials found on the surface of asteroids that have currently been studied, can withstand impacts of the intensity experienced by a sample return capsule during direct reentry.     

轻型塔架挠度速算法

本文介绍了轻型塔架的挠度速算法,并以三角形截面的钢塔架为例题作了计算公式推导。这种方法具有计算简单和具有足够精度的优点。