新的航空图像道路检测与跟踪算法

介绍了一种新的面向智能无人机应用的道路检测与跟踪算法.首先从电子道路地图中得到标示道路初始区域的合成图像,然后利用光学图像的距离变换图像、合成图像的边缘图像等信息把道路检测问题表述为一最优化问题,最后利用迭代算法解此问题得到路面区域.道路跟踪利用前一帧检测结果的预测值初始化其对应的优化问题.实验证明该方法具有较高的稳定性和适应能力.      

基于EBA-FLC的飞机急滚机动分支分析与控制

结合扩展分支分析(EBA)和模糊逻辑控制(FLC),提出了一种新的闭环分支控制方法,即EBA-FLC方法,并将其应用于某机动飞机的无侧滑滚转机动研究。揭示了飞机全局非线性动力学特性,实现了无侧滑滚转机动的闭环分支控制,使飞机在大范围内具有期望的动力学特性,改善了飞机无侧滑滚转机动的动态和稳态特性。     

一种过失速区飞行敏捷性评估方法的研究

在评估过失速机动飞行的敏捷性中，首先建立了具有过失速机动（ＰＳＴ）能力的战斗机Ｆ２的数学模型，对常规战斗机Ｆ１与ＰＳＴ战斗机Ｆ２的空战进行了数值仿真，计算了在两架战斗机中Ｆ２首先攻击时间（ｔ１）和攻击时间范围（ＴＷＩＦＥ）。结果表明，战斗机Ｆ２比Ｆ１更具有空中格斗优势，空战中发动机推力、迎角变化率、操纵规律和离轴发射角（μ０）等因素对战斗机过失速机动敏捷性有一定影响。     

CXG—2型磁悬规转子横向稳定的研究

本文针对CXG-1型磁悬规的转子横向振动现象进行了分析探讨,提出CXG-2型磁悬规的转子横向阻尼方案,并给出实施后的实验结果。     

Maneuvering target tracking with colored noise

It is known that colored noise may degrade the performance of a tracking algorithm. A common remedy is to model colored noise as an autoregressive (AR) process and apply the measurement difference method. One problem with the approach is that the AR parameters are usually unknown. In this work, we propose a new method to adaptively estimate the AR parameters. It is shown that this method is simple and practically feasible. We incorporate oar method into the interacting multiple model (IMM) tracking algorithm and show that the performance is almost as good as that in the known parameters case     

Cleaning space debris with a space-based laser system

High-energy pulsed laser radiation may be the most feasible means to mitigate the threat of collision of a space station or other valuable space assets with orbital debris in the size range of 1–10 cm. Under laser irradiation, part of the debris material is ablated and provides an impulse to the debris particle. Proper direction of the impulse vector either deflects the object trajectory or forces the debris on a trajectory through the upper atmosphere, where it burns up. Most research concentrates on ground-based laser systems but pays little attention to space-based laser systems.There are drawbacks of a ground-based laser system in cleaning space debris. Therefore the placement of a laser system in space is proposed and investigated. Under assumed conditions,the elimination process of space debris is analyzed. Several factors such as laser repetition frequency, relative movement between the laser and debris, and inclination of debris particles which may exercise influence to the elimination effects are discussed. A project of a space-based laser system is proposed according to the numerical results of a computer study. The proposed laser system can eliminate debris of 1–10 cm and succeed in protecting a space station.     

An improved quaternion Gauss–Newton algorithm for attitude determination using magnetometer and accelerometer

For the vector attitude determination, the traditional optimal algorithms which are based on quaternion estimator(QUEST) measurement noise model are complicated for just two observations. In our application, the magnetometer and accelerometer are not two comparable kinds of sensors and both are not small field-of-view sensors as well. So in this paper a new unit measurement model is derived. According to the Wahba problem, the optimal weights for each measurement are obtained by the error variance researches. Then an improved quaternion Gauss–Newton method is presented and adopted to acquire attitude. Eventually, simulation results and experimental validation employed to test the proposed method demonstrate the usefulness of the improved algorithm.     

用CT值推导人体组织属性参数的方法及改进

蒙特卡罗方法是计算精度最高的人体组织剂量计算方法。常见的蒙特卡罗模拟程序,如M CNP,EG S4等都自带了各种介质的截面数据,而剂量计算的一个重要步骤就是得到人体组织的属性参数——质量密度和化学组成。本文主要介绍了两种根据医学影像CT值推导人体组织属性参数的方法——区间法和两分法,并经过分析比较认为两分法比区间法具有更高的精确度和可行性。同时,针对两分法存在的不足和缺陷,本文将CT值全范围划分为七段,根据两分法的假设条件假设每一段均由两种不同的人体组织混合而成。在每一段CT值范围内,人体组织的质量密度和化学组成通过对两种假定物质参数的拟合得到。结果说明该方法所得到的人体组织属性参数完全可以满足蒙特卡罗人体组织剂量计算的要求。     

基于全局气动优化方法的跨声速叶栅气动优化

提出了适用于叶栅三维气动设计优化的全局自动气动优化方法.对NASA Rotor 37转子叶栅进行了气动优化设计.利用该叶栅的试验数据校核了计算流体(CFD)程序的可靠性.以等熵效率最高为目标函数,在满足流量约束和总压比约束的条件下,完成了跨声速叶栅的气动优化设计.优化叶栅的等熵效率提高了1.66%,具有优秀的气动性能和变工况性能.优化结果表明,通过优化三维跨声速叶栅的型线和径向基迭方式,可以有效的减小跨声速叶栅的激波损失.      

火星进入舱开伞弹伞载荷动力放大系数研究与试验验证

首先推导了单自由度系统在矩形和半正弦波形脉冲冲击下响应谱动力放大系数与脉冲作用时间的理论解析公式,然后采用有限元显示冲击动力学分析方法,分析了火星探测器进入舱进入过程中开伞弹伞低频大冲击载荷的载荷波形、脉冲作用时间以及结构阻尼对进入舱主结构动力放大系数的影响;最后介绍了开伞载荷悬吊冲坠模拟冲击动载试验和弹伞载荷真实弹伞筒冲击动载试验。分析与试验结果表明:冲击作用时间在1 ms以下时,结构衰减效应明显,冲击作用时间大于5 ms后,动力放大系数同波形下趋于稳定;开伞载荷由于指数型前沿上升时间较长,动力放大系数基本为1;弹伞载荷上升前沿较陡,矩形前沿波放大倍数在1～2倍之间。上述研究可为火星探测器进入舱结构载荷条件的确定提供参考。