转子-支承耦合结构的模型修正研究

在转子-支承耦合结构的动力学分析过程中,结构模态参数计算结果与实验测试结果往往存在较大差异。针对此问题,应用优化算法对结构动力学模型进行修正,使计算模型能更准确地反映结构特性。建立由梁单元、盘单元、弹性支承单元组成的结构动力学有限元模型;选择优化目标函数、设计参数,并对各参数进行灵敏度分析。应用粒子群算法对选取的设计参数进行优化,得到最优模型。利用转子-滚动轴承实验器进行验证,结果表明,方法能够有效地实现转子-支承耦合结构的动力学模型修正,修正后模型更接近实际结构。     

基于A320飞机横航向控制律架构的LQ设计

空客A320飞机横航向控制律采用特征结构配置方法计算闭环增益,实现了期望特征值的配置及横航向关键参数之间的解耦。基于A320横航向控制律架构,提出使用线性二次型(Linear Quadratic,简称LQ)方法,对闭环增益进行重新设计。首先根据期望的特征值引入关键参数的频域整形环节,而后通过调整二次型性能指标加权矩阵实现期望特征值的逼近及关键参数之间的解耦,并求得闭环反馈增益,最后在特征结构、稳定裕度和横航向解耦效果方面与空客设计结果作了对比分析。仿真结果表明,LQ设计可获得与特征结构配置设计相近的结果,即得到接近期望值的特征值,并实现关键变量的解耦,同时保证了闭环稳定裕度。     

Ⅲ—Ⅴ族四元固溶体中原子近邻及次近邻的键长表达方式

基于ＦＤＵＣ模型和Ⅲ－Ⅴ族元素共价半径不变的假设，本文出了Ⅲ－Ⅴ族固溶体中原子近邻和次近邻的键长表达式。这套键长表达式除依赖于四个Ⅲ－Ⅴ族元素的含量（ｘ，ｙ）外，只与四个纯化合物的晶胞参数或这四个Ⅲ－Ⅴ族元素的共价半径有关。而且也含盖了相应的伪二元固溶体的情况。本文还对其他的理论模型作了进一步的比较和讨论。     

(001)SiO2衬底上LiNbO3光波导薄膜的制备

采用脉冲激光淀积技术，在（００１）取向的ＳｉＯ２衬底上制备了ＬｉＮｂＯ３薄膜。为了防止淀积过程缺氧，往淀积腔内充入１０～１５Ｐａ的流动氧气，淀积速度０．３～１．０ｎｍ／ｍｉｎ，淀积时间１ｈ，淀积结束后，充入０．６Ｐａ的氧气，在６５０℃保温０．５ｈ。采用ｘ射线衍射和扫描电镜对ＬｉＮｂＯ３薄膜的微观结构及表面形貌进行了检测。结果表明：ＬｉＮｂＯ３薄膜具有（０１２），（０２４）典型的ＬｉＮｂＯ３粉末晶体衍射峰，薄膜成分晶体结构比较纯净，而且薄膜表面光滑。利用棱镜耦合法将波长为０．６３８μｍ的激光束耦合到ＬｉＮｂＯ３薄膜中，观察到ＬｉＮｂＯ３薄膜具有较好的光波导性能，可望应用于非线性光学器件     

Disturbance observer based model predictive control for accurate atmospheric entry of spacecraft

Facing the complex aerodynamic environment of Mars atmosphere, a composite atmospheric entry trajectory tracking strategy is investigated in this paper. External disturbances, initial states uncertainties and aerodynamic parameters uncertainties are the main problems. The composite strategy is designed to solve these problems and improve the accuracy of Mars atmospheric entry. This strategy includes a model predictive control for optimized trajectory tracking performance, as well as a disturbance observer based feedforward compensation for external disturbances and uncertainties attenuation. 500-run Monte Carlo simulations show that the proposed composite control scheme achieves more precise Mars atmospheric entry (3.8?km parachute deployment point distribution error) than the baseline control scheme (8.4?km) and integral control scheme (5.8?km).     

并行组合扩频通信系统变换域干扰抑制技术研究

为提高并行组合扩频通信系统抵抗窄带干扰的能力,研究自适应多门限和DT-FCME两种变换域算法抑制并行组合扩频通信系统中窄带干扰的问题。经仿真验证,两种算法能够对系统中高斯白噪声环境下的多种窄带干扰起到较好的抑制效果。最后对比分析了两种算法抑制不同类型窄带干扰时的优缺点。     

A nonlinear background removal method for seismo-ionospheric anomaly analysis under a complex solar activity scenario: A case study of the M9.0 Tohoku earthquake

A precise determination of ionospheric total electron content (TEC) anomaly variations that are likely associated with large earthquakes as observed by global positioning system (GPS) requires the elimination of the ionospheric effect from irregular solar electromagnetic radiation. In particular, revealing the seismo-ionospheric anomalies when earthquakes occurred during periods of high solar activity is of utmost importance. To overcome this constraint, a multiresolution time series processing technique based on wavelet transform applicable to global ionosphere map (GIM) TEC data was used to remove the nonlinear effect from solar radiation for the earthquake that struck Tohoku, Japan, on 11 March, 2011. As a result, it was found that the extracted TEC have a good correlation with the measured solar extreme ultraviolet flux in 26–34 nm (EUV_26–34) and the 10.7 cm solar radio flux (F_10.7). After removing the influence of solar radiation origin in GIM TEC, the analysis results show that the TEC around the forthcoming epicenter and its conjugate were significantly enhanced in the afternoon period of 8 March 2011, 3 days before the earthquake. The spatial distributions of the TEC anomalous and extreme enhancements indicate that the earthquake preparation process had brought with a TEC anomaly area of size approximately 1650 and 5700 km in the latitudinal and longitudinal directions, respectively.     

判断力权值的确定方法及AHP中群组判断矩阵的形成

在ＡＨＰ模型中，请一组专家对某一属性进行评价，根据专家的判断能力，给出判断力权值，再通过适当的数学处理方法，可得最优判断矩阵，这是ＡＨＰ中构造判断矩阵的一种新方法。     

一种便携式多通道精密测温仪

介绍了利用数字式温度传感器 DS1 6 2 4构成的多路温度测量仪器。它具有线路简单 ,测量精度高的优点 (在 - 5 5～ 1 2 5°C内 ,精度优于 0 .0 5°C) ;带有计算机接口 ,能够实现长时间连续测量。     

先进的短距起飞垂直降落(ASTOVL)升力风扇飞机的动态逆控制

研究了推力矢量喷管、升力风扇以及气动舵面共同作用下 ASTOVL升力风扇飞机的飞控问题 ,采用非线性动态逆理论进行控制系统的设计。针对 ASTOVL升力风扇飞机的俯仰控制设计了动态逆控制律 ,并将所设计的控制律进行了仿真。结果表明 ,该方法能够满足控制系统性能的要求 ,具有工程应用前景。