提高航天传输型CCD相机地面像元分辨率方法研究

文章首先对空间传输型遥感相机提高像元分辨率的几种常规和非常规方法做了简介,在分析这些方法的优缺点以及以采样定理为依据分析我国现有CCD相机光学截止频率和CCD采样频率存在的矛盾的基础上探讨了高模式采样技术和超模式采样技术,经过比较这两种采样模式,认为超模式采样技术更具有工程可行性和优越性。然后对超模式采样计算机图像仿真结果进行了分析。     

激波在狭缝中绕射过程研究

针对固体火箭发动机药柱存在裂纹的情况，对运动激波在狭缝中绕射传播的非定常流场进行了计算，得到了清晰的流场变化图谱，从流场图中可分辨出激波在狭缝中的传播过程。对不同深宽比的狭缝进行研究，发现流场结构存在明显差别，在深宽比较小时狭缝内压力波振荡较小，当深宽比超过一定值时狭缝内的压力波产生剧烈振荡。研究结果表明，该方法可很好地描述激波在狭缝中的传播过程。     

克服天线罩瞄准误差影响的一种鲁棒导引控制器设计方法

本文首先分析了某类导弹系统的稳定性，然后对天线罩瞄准线误差斜率Ａ的摄动对寻的制导控制系统稳定性的影响进行了研究。在此基础上，文章提出了鲁棒导引控制器的设计方法。仿真结果表明，按此方法设计出的控制器对于Ａ的摄动具有满意的鲁棒性，该方法在某类导弹控制系统的设计中得到应用，效果良好。     

基于RBF网络的惯导系统初始对准

建立了惯导系统（ＩＮＳ）初始对准的线性和非线性误差模型。分析了径向基函数（ＲＢＦ）网络的结构和工作原理。研究了ＲＢＦ网代替初始对准中的卡尔曼滤波器的实现方法。通过仿真表明，用神经网络进行初始对准，既可获得与卡尔曼滤波相同的对准精度，又提高了系统的实时性。     

VentureStar… reaping the benefits of the X-33 program

Major X-33 flight hardware has been delivered, and assembly of the vehicle is well underway in anticipation of its flight test program commencing in the summer of 1999. Attention has now turned to the operational VentureStar^TM, the first single-stage-to-orbit (SSTO) reusable launch vehicle. Activities are grouped under two broad categories: (1) vehicle development and (2) market/business planning, each of which is discussed. The mission concept is presented for direct payload delivery to the International Space Station and to low Earth orbit, as well as payload delivery with an upper stage to Geosynchronous Transfer Orbit (GTO) and other high energy orbits. System requirements include flight segment and ground segment. Vehicle system sizing and design status is provided including the application of X-33 traceability and lessons learned. Technology applications to the VentureStar^TM are described including the structure, propellant tanks, thermal protection system, aerodynamics, subsystems, payload bay and propulsion. Developing a market driven low cost launch services system for the 21st Century requires traditional and non-traditional ways of being able to forecast the evolution of the potential market. The challenge is balancing both the technical and financial assumptions of the market. This involves the need to provide a capability to meet market segments that in some cases are very speculative, while at the same time providing the financial community with a credible revenue stream. Furthermore, the market derived requirements need to be assessed so as not to impose unnecessary requirements on the vehicle design that add unreasonable cost to the development of the system, yet provides the right capabilities for new markets that could be triggered by dramatically lower space transportation prices.     

红外型空空导弹智能制导律研究

本文论述了红外型空空导弹应用智能控制的理论基础及结构特点，以多级智能控制的框架和机理设计出以比例导引为主、智能控制为辅的变指令智能制导律，并编制计算机软件以数字仿真的形式验证变指令智能制导规律的有效性和可行性     

具L2有界不确定性扰动系统最优跟踪问题的时域解

本文对Ｌ２有界不确定性扰动下的一性系统在时域提出Ｍａｘｍｉｎ最优跟踪问题，给出了问题的时域状态反馈解，这一问题与相应的Ｈ∞问题具有某种一致性，因此，问题的求解方法可为解决领域不确定系统的Ｈ∞最优跟踪问题提供一种时域途径。     

Phugoid oscillations in optimal reentry trajectories

A major problem with operations of lifting reentry vehicle having an aft center-of-gravity location due to large engine mass at the rear is the required hypersonic trim to fight the desired trajectory. This condition is most severe for lifting maneuvers. As a first step toward analyzing this problem, this paper considers the lift requirement for some basic maneuvers in the plane of a great circle. Considerations are given to optimal lift control for achieving the maximization of either the final altitude, speed or range. For the maximum-range problem, phugoid oscillation along an optimal trajectory is less severe as compared to a glide with maximum lift-to-drag ratio. An explicit formula for the number of oscillations for an entry from orbital speed is proposed.     

航迹跟踪的优化方法研究

最优航迹跟踪要求飞机的实际飞行航迹与理想航迹的偏差最小,但若采用按偏差的最优控制方法,会造成控制变量的剧烈震荡.为了解决控制变量的剧烈震荡问题,提出了一种新的偏差-微分综合控制方法.通过对参考航迹的跟踪验证,表明该方法有效地解决了控制变量最优解的振荡问题,并实现了精确的航迹跟踪性能.     

数值模拟高超音速化学非平衡流的隐式格式

针对高超音速化学非平衡流提出了两种隐式格式.一种是近似因子分解算法对角化形式在隐式TVD(全变差递减)格式上的推广,另一种可视为隐式TVD格式的LU分解形式.数值试验表明,本文给出的算法保持了TVD格式的高分辨率特性,同时计算量大大减少,是高超音速化学非平衡流数值模拟的有效方法.