非Markov系统的可靠性仿真

在进行非Markov系统的可靠性仿真时,为获得准确的状态转移时间抽样,提出剩余分布的近似抽样(ASRD)方法,利用多个均匀分布拟合一般形式的剩余分布,通过拟合参数d调整抽样精度和抽样效率。在此基础上,提出基于强制转移(FT)策略的ASRD(FT-ASRD)仿真方法。多个算例结果表明,当5≤d≤10时,FT-ASRD相对于常规仿真方法具有更高的效率,而且仿真结果的相对误差较小。     

基于多核支持向量机的飞机重着陆诊断

将支持向量机应用于飞机重着陆的诊断研究。通过分析飞机着陆阶段的运动方程,确定造成飞机重着陆的主要影响因素,将传统的单一指标诊断扩展到多指标诊断。提出一种多核支持向量机,并在此基础上建立飞机重着陆诊断模型。与传统支持向量机和神经网络模型比较表明,该模型精度高,具有更强的泛化能力。     

一种用于无人机着陆的地平线提取算法

针对着陆场不同天地场景中的地平线提取问题,结合Ostu方法与Hough变换,提出一种用于无人机着陆的地平线分步提取算法。在确定初始地平线的基础上,对其做粗化处理,得到目标地平线所在子图像域,在子图像域中完成最终目标的地平线提取。实验结果表明,该算法能准确有效地提取不同天地场景中的地平线。     

Analysis of microwave brightness temperature of lunar surface and inversion of regolith layer thickness:Primary results of Chang-E 1 multi-channel radiometer observation

In China’s first lunar exploration project, Chang-E 1 (CE-1), a multi-channel microwave radiometer was aboard the satellite, with the purpose of measuring microwave brightness temperature from lunar surface and surveying the global distribution of lunar regolith layer thickness. In this paper, the primary 621 tracks of swath data measured by Chang-E 1 microwave radiometer from November 2007 to February 2008 are collected and analyzed. Using nearest neighbor interpolation based on the sun incidence angle in ...     

火星着陆任务落点误差快速分析方法

在火星着陆任务设计中,为高效地评估进入点导航误差等动力学方程中的不确定因素对着陆精度的影响,引入Galerkin投影法则,提出一种火星着陆落点不确定度快速预报与分析方法．该方法采用Wiener-Askey正交多项式逼近着陆器状态,将落点误差的预报问题转换为1个确定性微分方程的求解问题．最后以我国未来实施火星着陆探测为背景,分别用本文算法和蒙特卡洛方法进行数值仿真分析,结果表明,本文算法能够对落点偏差进行快速分析,准确预测其均值和方差,且计算效率明显提高．     

液压式阻拦系统的数学建模及仿真

为了确定舰载机着舰过程中的动态变化,对美国航母上MARK7 Mod1型液压式舰载机阻拦系统开展研究,建立的阻拦系统的数学模型.利用Matlab对所建立的阻拦系统模型进行仿真分析,论述了着舰过程中阻拦系统和舰载机的动态变化,分析了液压装置和定长冲跑控制装置的在着舰过程中的作用.结果表明:利用MARK7 Mod1型阻拦系统,航母上的舰载机在一定的速度范围内着舰降落,都能够在固定的甲板长度内平稳的拦停,实现舰载机的安全着舰.     

An experimental study of pilots' control characteristics for flight of an STOL aircraft in backside of drag curve at approach and landing

Abstract

In general, most vehicles can be modelled by a multi-variable system which has interactive variables. It can be clearly shown that there is an interactive response in an aircraft's velocity and altitude obtained by stick control and/or throttle control. In particular, if the flight conditions fall to backside of drag curve in the flight of an STOL aircraft at approach and landing then the ratio of drag variation to velocity change has a negative value (ΔD/Δu<0) and the system of motion presents a non-minimum phase. Therefore, the interaction between velocity and altitude response becomes so complicated that it affects to pilot's control actions and it may be difficult to control the STOL aircraft at approach and landing.

In this paper, experimental results of a pilot's ability to control the STOL aircraft are presented for a multi-variable manual control system using a fixed ground base simulator and the pilot's control ability is discussed for the flight of an STOL aircraft at backside of drag curve at approach and landing.     

求解机场终端区飞机着陆调度问题的遗传算法

空中管制员需为到达的飞机安排跑道并计算着陆时间,以飞机空中延误最小为出发点研究了多跑道的飞机着陆调度问题,约束条件为每架飞机的着陆时间应落在规定的时间窗内及相邻两架飞机应满足最小时间间隔。针对该问题设计了一种遗传算法对问题进行求解,其中染色体由飞机排序链表和跑道链表组成,相应的交叉和变异算子也做了改进设计。仿真实验用数据库OR-Library中的实例验证了该算法的有效性。     

Effect of design of a sex-pheromone-baited delta trap on behavior and catch of maleEpiphyas postvittana (Walker)

Through field trials and wind-tunnel studies, we have demonstrated that certain structural features of a sex-pheromone-baited delta trap affect catch of light-brown apple moth,Epiphyas postvittana, males, by influencing behaviors used to enter and exit the trap. Field catch of males was dependent upon length (and width) of the trap, with increases in length yielding linear increases in catch. In the wind tunnel, similar numbers of males entered the two traps, but significantly fewer males exited the longer trap within 1 min after entering it. Although males landed on the sticky surface at similar distances from the downwind entrances of the traps, they were stuck farther upwind on the longer trap. Thus, it is probable that the increase in field catch with increase in trap length relates to the increase in distance (and hence time) that males walk on the sticky surface, towards the pheromone source, before attempting to exit. The bottom barriers (as well as additional barriers at the top and sides) at the entrances of the trap also significantly influenced trap catch. The barriers apparently influence trap catch in two ways. Firstly, they hinder the exit of males from the trap, thus diverting males back into the trap and increasing their chance of being caught. Secondly, they influence where the male lands on the sticky surface; with higher barriers, males land farther upwind (i.e., nearer the source), and thus farther from an exit. Finally, as the source was suspended higher above a horizontal surface, greater numbers of males landed on the source. This result shows that the position where a maleE. postvittana lands is influenced by the relationship of the source to the surface and suggests that trap catch of males may similarly be influenced (i.e., by inducing males to land farther from the exits).