“做中教”教学法在高职教学中的应用

阐述“教学做合一”教育思想的精髓及其教学观的主要内涵,论述高职教育应以实践教学为中心,教师在教学中应学会在“做中教”,努力达到“教学做合一”。     

Flight trajectory optimization of sun-tracking solar aircraft under the constraint of mission region

The optimal yawing angle of sun-tracking solar aircraft is tightly related to the solar azimuth angle, which results in a large arc flight path to dynamically track the sun position. However, the limited detection range of payload usually requires solar aircraft to loiter over areas of interest for persistent surveillance missions. The large arc sun-tracking flight may cause the target area on the ground to be outside the maximum coverage area of payload. The present study therefore develops an optimal flight control approach for planning the flight path of sun-tracking solar aircraft within a mission region. The proposed method enables sun-tracking solar aircraft to maintain the optimal yawing angle most of the time during daylight flight, except when the aircraft reverses its direction by turning flight. For a circular region with a mission radius of 50 km, the optimal flight trajectory and controls of an example Λ-shaped sun-tracking solar aircraft are investigated theoretically. Results demonstrate the effectiveness of the proposed approach to optimize the flight path of the sun-tracking aircraft under the given circular region while maximizing the battery input power. Furthermore, the effects of varying the mission radius on energy performance are explored numerically. It has been proved that both net energy and energy balance remain nearly constant as the radius constraint varies, which enables the solar aircraft to achieve perpetual flight at almost the same latitude as the large arc flight. The method and results presented in this paper can provide reference for the persistent operation of sun-tracking solar aircraft within specific mission areas.     

无阀式脉冲爆震火箭发动机运行稳定性实验

以无阀模式运行时,脉冲爆震火箭发动机可达到更高的运行频率,但容易出现连续燃烧、点火不成功以及运行频率与点火频率不一致等运行不稳定问题。为探索供给条件对运行稳定性的影响,采用乙烯为燃料、富氧空气为氧化剂,开展了实验研究,分析了氧化剂中氧气体积分数对运行稳定性的影响。结果表明,采用氧气体积分数分别为40%和66%的氧化剂时,当量比范围分别为1.2~1.7和0.8~2.3时才能产生稳定的爆震波;采用氧气体积分数66%的氧化剂时,可获得稳定爆震波的当量比范围较宽;稳定产生爆震波时,爆震管封闭端附近的压力振荡会向供给通道的上游传播,造成通道内介质的流动振荡,振荡频率与运行频率呈倍数关系;爆震波不稳定产生条件下,供给通道内的流动振荡表现为无规律的低频振荡,该振荡加剧了无阀无隔离模式运行的不稳定,故有必要在供给通道内加装压力反传抑制装置。     

宽马赫数二维曲面压缩高超声速进气道设计

为设计出工作范围为Ma 2~7的RBCC发动机进气道,利用压升规律可控的二维曲面压缩设计方法,以Ma 6为设计点设计了宽马赫数新型二元高超声速进气道气动型面,采用前掠侧板减小了进气道的内收缩比,在Ma 4以下采用顶板放气的方式来扩展进气道的工作范围。数值模拟研究了进气道的流场及性能,发现采用曲面压缩设计的新型二元进气道在Ma 4~7范围波系较少,流场结构良好,同时总压恢复较高,流量捕获能力强。通过顶板放气可实现在Ma 1.5~4范围内正常工作,放气量在15%以下。从流场和性能参数看,曲面压缩进气道在Ma 4以上性能良好,但在Ma 4以下流量捕获能力偏低。     

家庭安全监控的实时异常检测与分类算法

同时具有好的实时性和稳健性是基于视频的安全监控系统异常检测算法的难点问题.在家庭安全监控系统中同时利用像素的亮度分量和色度分量检测变化像素,解决摄像镜头由于大尺寸对象闯入引起的图像背景变化造成运动对象检测失败的问题;提出一种实时运动对象分类算法,综合利用开关灯检测、运动距离分析和皮肤探测多种方法,区分是否出现影响家庭安全的事件;提出3关键值背景维护算法,用于消除背景振动像素,减少虚假报警.实验表明,本文异常探测算法对视频监控系统异常探测和消除虚假异常报警具有较好的实时性和稳健性.      

Robust leaderless time-varying formation control for unmanned aerial vehicle swarm system with Lipschitz nonlinear dynamics and directed switching topologies

This paper tackles the robust leaderless Time-Varying Formation(TVF) control problem for the Unmanned Aerial Vehicle(UAV) swarm system with Lipschitz nonlinear dynamics, external disturbances and directed switching topologies. In comparison with the previous achievements on formation control problems, the UAV swarm system with Lipschitz nonlinear dynamics can accomplish the pre-designed TVF while tracking a pre-given trajectory which is produced by a virtual leader UAV in the presence of externa...     

Delphi与C++语言编程特点之比较

通过与功能强大的C语言比较,系统地介绍和总结了Delphi所采用语系Object Pascal中丰富的指针操作、位运算和编译预处理的特点和用法,用于指导Delphi程序员编写高质量的应用软件。     

空间旋转目标涡流消旋概念与仿真分析

针对消除空间旋转目标姿态旋转的问题,本文将第二代高温超导技术与涡流制动技术相结合,提出超导式涡流消旋的概念。然后,对涡流消旋的技术可行性进行了定性分析,通过对多种消旋技术手段的权衡比较归纳出涡流消旋的优势。接着,采用电磁张量理论,建立了电磁-涡流作用机理的精确磁场和涡流力矩模型;最后,考虑实际消旋的任务需求,对典型的高速旋转目标、低速旋转目标、以及复合旋转目标的消旋进行了动力学仿真研究。仿真结果表明,涡流消旋具有足够强大的制动能力,能有效消除目标的高速旋转或复合旋转运动。     

美军作战指挥标准研究

Xu Huifa;Zhang Xin(Unit 31002 of PLA,Beijing 100094,China;Coastal Defense College,Naval Aviation University,Yantai 264001,Shandong,China)     

基于精确反馈线性化控制的永磁同步电机低速运行特性研究

针对永磁同步电机(PMSM)低速运行时的速度跟踪精度差,使用输入输出精确反馈线性化控制,以探索高精度的PMSM低速运行控制特性。为了获取更好的精确控制性能,首先采用微分同胚变换和反馈线性化理论得到PMSM的输入输出精确反馈线性化的解耦模型,然后基于其解耦模型,实现了PMSM低速运行时的精确控制。仿真和试验结果表明:该方法能够快速跟踪负载转矩和指令速度,具有过冲小、静态误差小、鲁棒性强、控制精确性高等优点。