Adaptive dynamic surface control of a hypersonic flight vehicle with improved tracking

This work presents a nonlinear adaptive dynamic surface air speed and a flight path angle control design procedure for the longitudinal dynamics of a generic hypersonic flight vehicle. The proposed design scheme takes into account the magnitude, rate, and bandwidth constraints on the actuator signals. A new approach is used to enhance tracking performance and avoid a large initial control signal. The uncertain nonlinear functions in the flight vehicle model are approximated by using radial basis function neural networks. A detailed stability analysis of the designed controllers shows that all the signals of the closed‐loop system are uniformly ultimately bounded. The robust performance of the design scheme is verified through numerical simulations of the flight vehicle model for various parameter variation test cases. Copyright © 2011 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

基于蚁群优化的SVM及其应用研究

针对蚁群算法的容易陷入局部最优解的问题,对连续蚁群算法的全局转移因子和挥发因子进行了改进.在搜索过程中,蚂蚁利用前一代最优解的位置及信息素强度决定最优解转移步长及概率,对每一代搜索过程,利用动态的全局转移因子来确定蚂蚁应该进行如何搜索,保证蚂蚁能够得到更多的搜索空间,解决了蚁群算法"早熟"的现象.利用优化后的支持向量机(C-SVR和C-LSSVM)建立了某型航空发动机起动过程的数学模型.通过实际的发动机数据对模型的有效性进行了验证,结果表明,C-SVR和C-LSSVM泛化性能优于ε-SVR和LSSVM.     

Impact of the Boeing 767 Aircraft into the World Trade Center

A numerical simulation of the aircraft impact into the exterior columns of the World Trade Center (WTC) was done using LS-DYNA. For simplification, the fuselage was modeled as a thin-walled cylinder, the wings were modeled as box beams with a fuel pocket, and the engines were represented as rigid cylinders. The exterior columns of the WTC were represented as box beams. Actual masses, material properties and dimensions of the Boeing 767 aircraft and the exterior columns of the WTC were used in this analysis. It was found that about 46% of the initial kinetic energy of the aircraft was used to damage columns. The minimum impact velocity of the aircraft to just penetrate the exterior columns would be 130?m/s. It was also found that a Boeing 767 traveling at top speed would not penetrate exterior columns of the WTC if the columns were thicker than 20?mm.     

Formal verification of conflict detection algorithms

Safety assessment of new air traffic management systems is a main issue for civil aviation authorities. Standard techniques such as testing and simulation have serious limitations in new systems that are significantly more autonomous than the older ones. In this paper, we present an innovative approach for establishing the correctness of conflict detection systems. Fundamental to our approach is the concept of trajectory, and how we represent a continuous physical trajectory by a continuous path in the x-y plane constrained by physical laws and operational requirements. From the model of trajectories, we extract, and formally prove, high-level properties that can serve as a framework to analyze conflict scenarios. We use the AILS (Airborne Information for Lateral Spacing) alerting algorithm as a case study of our approach. Published online: 19 November 2002     

飞行器与机器人的区域目标搜索最优控制

描述了飞行器导航或移动机器人的区域搜索控制问题.为了使该问题得到优化解决,首先建立了基于区域搜索控制问题的模型,将最优控制原理运用于此模型上,得到其伴随方程和控制方程,后基于此分析了该问题,且讨论了此方法的可行性.然后,通过解出问题的规范方程,使飞行器导航或移动机器人的区域搜索控制问题最终得以解决,进而推导得到了飞行器导航或移动机器人的区域目标搜索最优控制以及最优轨线.最后,通过计算仿真结果表明,该方法是有效的,故为飞行器导航与移动机器人的区域目标搜索最优控制提供了依据.     

海洋大气表面边界层

介绍大气表面边界层的热力和动力性质,平均气象要素的垂直分布规律,大气湍流的谱模式以及获取湍流边界层统计量的方法,供飞行器研究及海洋工程工作者参考。     

晴空飞机尾流的雷达探测性能分析

该文分析了晴空飞机尾流RCS(雷达截面积)的频域特性和时变特性,导出了相参多普勒雷达探测飞机尾流的LMP(局部最大势)检测器及其检测概率、虚警概率的解析表达式,在此基础上导出了尾流探测的雷达方程。仿真分析结果表明：垂直入射的尾流探测性能一般优于斜入射探测;当雷达观测时间较长时,斜入射探测性能随雷达距离分辨单元的增大而改善;对于单位长度RCS为-80~-60 dBm2/m的飞机尾流,其雷达探测距离可达30~100 km。     

基于Petri网工作流网在舰载机出航准备建模中的应用

基于Petri网的工作流网的舰载机出航准备建模,将舰载机出航准备工作流网分为:与舰载机起飞降落紧密相关的活动、飞行甲板上的舰载机的活动和进入机库舰载机的活动.任何一架舰载机在航母降落,代表该舰载机的托肯会由C1库所进入工作流网,使整个工作流网启动.每个托肯根据航母指挥机构的命令选择不同流向,并向指挥机构显示舰载机出航准备状态.当舰载机接到起飞命令,升空作战时,流程结束.     

基于多层快速多极子和有限元混合求解的飞行器天线布局设计

设计一种微带天线,以该天线为基础进行飞行器天线布局设计,并考虑遮挡的判断问题。模型仿真采用多层快速多极子和有限元的方法混合求解,设置混合场积分方法提高收敛性,解决了电大尺寸模型复杂电磁场的计算问题,兼顾运算速度和精度,得出并分析飞行器上3天线、4天线、5天线以不同方式布局的远场方向图仿真结果,并提出一种方向图评估法则,对飞行器天线布局有一定参考意义。     

飞机电子设备电磁兼容性分析

本文分析了现代民航机载电子设备的电磁环境及引起电磁干扰的原因,并从飞机总体结构和可靠性设计两方面分析了飞机生产商和维护部门在飞机电子设备电磁兼容方面所采取的各种措施.