同步磁阻电机直接转矩控制系统研究

鉴于矢量控制对电机参数依赖性强的问题,借鉴现有永磁同步电机数学模型及其直接转矩控制的相关理论,分析同步磁阻电机的数学模型,提出了同步磁阻电机的直接转矩控制方法,包括空间电压矢量的计算、磁链和转矩的滞环控制等;并基于位置信息的估算,设计了速度的闭环控制器。构建了系统的仿真模型,并对电机的稳态和动态性能进行了仿真分析。由仿真结果可知,所提方法设计的系统能够在较宽的转速范围内变速运行。     

基于线性调频扩频的单基站室内定位系统研究

基于WLAN、蓝牙等无线信号的室内定位系统在布设与组网阶段需要布设大量的节点,在推广过程中严重受制于布设成本,因而提出了一种基于线性调频扩频(Chirp Spread Spectrum,CSS)信号的单基站室内定位系统及相关定位算法,结合使用线性调频测距方法与自主角度估计方法,测距精度优于1m,测角精度达1.5°,可为地下停车场等人员相对稀疏、定位精度需求相对较低的应用场景提供低成本的覆盖。经过室内停车场场景试验,该室内定位系统可在仅使用单一基站情况下,在约60m半径内提供1~3m的定位精度。     

Photoelectric and CCD photometry of 951 Gaspra

The asteroid 951 Gaspra is a fly-by target for the Galileo space mission. This encounter, planned for October 1991, will represent the first possibility to show an asteroid in close-up. In preparation to this close encounter an earth-based international observing campaign started in 1988 /1,2/, with the goal to provide a substantial data base on the photometric and rotational properties of this object. This will allow on one side to support and optimize the planning of the fly-by and, on the other side, to verify the accuracy of current models for the determination of shapes, surface textures, spin axis orientation and composition. In this paper we present the composite lightcurve of 951 Gaspra obtained from photoelectric and CCD observations, carried out during the 1990 apparition at the observatories of Asiago, Catania and Loiano (Italy).

We have determined the sidereal rotational period, the prograde sense of rotation, the H and G parameters and the B-V and V-R color indices.     

飞机灯光告警系统自动测试设备研制

告警控制盒是飞机灯光告警系统的核心部件,采集来自飞机各系统的告警信号,经分析处理后控制信号灯盒点亮、熄灭与闪烁来表达不同的告警信息。对告警控制盒进行了测试需求分析,基于ATE硬件平台设计了自动测试电路,采用了总线程控仪器和图形化测试软件等技术,实现了告警控制盒的功能和性能自动测试。经部队使用表明,该设备具有测试效率高、人机交互界面友好和操作简单等优点。     

Characteristics of pulsed plasma synthetic jet and its control effect on supersonic flow

The plasma synthetic jet is a novel flow control approach which is currently being studied. In this paper its characteristic and control effect on supersonic flow is investigated both experimentally and numerically. In the experiment, the formation of plasma synthetic jet and its propagation velocity in quiescent air are recorded and calculated with time resolved schlieren method. The jet velocity is up to 100 m/s and no remarkable difference has been found after changing discharge parameters. When applied in Mach 2 supersonic flow, an obvious shockwave can be observed. In the modeling of electrical heating, the arc domain is not defined as an initial condition with fixed temperature or pressure, but a source term with time-varying input power density, which is expected to better describe the influence of heating process. Velocity variation with different heating efficiencies is presented and discussed and a peak velocity of 850 m/s is achieved in still air with heating power density of 5.0 · 1012W/m3. For more details on the interaction between plasma synthetic jet and supersonic flow, the plasma synthetic jet induced shockwave and the disturbances in the boundary layer are numerically researched. All the results have demonstrated the control authority of plasma synthetic jet onto supersonic flow.     

压气机转子叶片的抑颤设计

为了建立适用于工程设计的叶片抑颤方法,以一高压压气机转子叶片为对象开展了叶片颤振特性与其结构参数的关联性研究。采用基于相位延迟边界条件的能量法和特征值法对原转子叶片模型的气动弹性稳定性进行评估,通过分析近失速工况下的非定常气动功密度分布,对叶片安装角沿径向分布、弦长和叶尖间隙等设计参数进行调整,以明确各参数对气动弹性稳定性的影响,最终达到提高气动阻尼的目的。研究结果表明:叶尖间隙对气动阻尼的影响较大,安装角次之,弦长影响相对较小。叶片气动阻尼随叶尖间隙的变化并非单调,而是存在一个叶尖间隙使其气动阻尼最小,即叶片气动弹性稳定性最差。减小进口气流攻角和增加折合频率,能够提高气动阻尼,设计中可以通过调节安装角来减小气流攻角,增加弦长来增大折合频率。考虑到对叶片气动性能的影响,在调节安装角时通常要保证进口气流攻角的改变量不超过5°,调节弦长和叶尖间隙时要保证各结构构件不发生碰摩。     

民机起落架系统研制适航工作分析

在梳理国家适航法规要求、适航管理机制、民机研制过程、适航审定过程的基础上,对民机起落架系统研制过程相关适航工作要求开展分析,明确了民机起落架系统随航空器型号合格审定、生产许可审定和适航合格审定一起批准（随机适航）过程中的适航工作目标和主要适航工作内容,并对起落架系统持续适航工作进行了简要论述。民机起落架系统研制随机适航工作虽然属于航空器适航取证工作的组成部分,但起落架系统研制单位仍承担其产品适航性的“第一责任”,研究内容对民机起落架系统研制单位开展项目策划和研制体系建设具有指导作用。     

基于图像卷积的地图匹配算法

地图匹配定位是一种主流的车载导航定位方法,其以车辆轨迹数据和路网地图为基础,将车辆位置估计输出到路网地图上。该过程可对车辆定位结果进行修正,是车辆导航、交通诱导、交通预测等应用的基础。针对现有地图匹配算法存在的一些问题,如算法流程依赖路口匹配精度,在较大初始误差场景下寻路正确率较低,以及寻路结果错误易影响后续匹配精度等,提出了一种基于图像卷积的地图匹配方法。利用图像卷积方式对比了车辆轨迹与道路的几何特征,以实现匹配定位,从而确保了初始误差较大场景下的匹配精度,并且避免了由寻路错误所引发的相关问题。     

爱因斯坦相对论诞生之初的失误

近光速的宇宙航行需要遵循相对论力学。然而,作者发现爱因斯坦1905年创立相对论的第一篇论文有误：他的代数运算失误,他运用“光源-光线-反射镜”模型也有误。正确的运算和运用这个模型得到的应该是普适的同时性。