叶片盘的旋转失速振动响应分析

稳定气动力状态下的叶片盘的模型由连续系统组成。利用弹性和波动理论以获得叶片盘响应。响应是带有波动模态阻尼的模态解。由模态解,可以得到共振相对转速的表示方法和解释试验中的某些现象,此外,讨论了在气流稳定和失速状态下的广义共振情况。最后得出的结论是:在均匀稳定气流中不出现波动响应,但在失速流动下,波动响应呈随机的波动振动,而此时不产生驻波共振。     

前端襟翼对带涡襟翼的细长翼影响的实验研究

 为改善带涡襟翼的细长翼的升阻特性,在其上附加了前端襟翼和后缘襟翼。通过前端涡(前端襟翼上产生)和前缘涡(涡襟翼上产生)相互作用对气动特性影响的研究,得到能够改善升阻特性的方法。结果表明,涡的相互作用对涡的产生和发展有很大影响,因而影响细长翼气动特性。附加前端襟翼和后缘襟翼是必要的。由此得到既能增升又能减阻的前端襟翼偏转角。     

A comprehensive study of the 2016 Mw 6.0 Italy earthquake based on high-rate (10 Hz) GPS data

The 2016 M_w 6.0 Italy earthquake is successfully recorded by the near-field 10?Hz GPS and 200?Hz Strong Motion (SM) stations, providing valuable data for this study. A comprehensive study of this earthquake is carried out based on GPS data, which contains coseismic deformations analysis, noise analysis, seismic wave picking, and magnitude determination. The noise of most GPS-derived displacement waveforms can be described as a combination of white noise, flicker noise, and random walk noise after the earthquake occurrence, and the spectral indices vary significantly for most stations, implying that the seismic signals have affected the noise characteristic of GPS-derived displacement waveforms. S-transform is employed to assess the GPS capability to detect the seismic arrival time. The SM station AMT and the GPS station AMAT are in good agreement in seismic wave picking, and the difference is only 1.2?s in the north component, suggesting that the outcome of seismic wave picking using GPS data is reliable. Then, a classic empirical formula is employed to determine the moment magnitude. A robust moment magnitude (Mw 5.90) can be estimated by the nine GPS stations with about 23.9?s. If four GPS stations near the epicenter is chosen to determine the magnitude, it only take 13.0?s to retrieve a reliable preliminary (Mw 5.82) magnitude, which is 5.4?s ahead of nine stations. In addition, Cross Wavelet Transform (XWT) is adopted to measuring the correlation and phase relationship between GPS and SM records. The result of XWT analysis indicates 10?Hz GPS is capable of capturing reliable and accurate coseismic dynamic deformations, as evidenced by the XWT-based semblance being close to 1 between GPS and SM records. The above results confirm the capability of 10?Hz GPS to capture coseismic dynamic deformations, detect seismic arrival time, and determine earthquake magnitude. Moreover, rapid magnitude determination based on 10?Hz GPS data can be regarded as an important supplement to Earthquake Early Warning (EEW).     

飞行器航迹倾角的自适应动态面控制

针对飞行器纵向模型具有参数不确定性和外界干扰的特点,提出一种飞行器航迹倾角的自适应动态面控制方法.动态面控制方法通过引入一阶低通滤波器避免了传统反演设计存在的"微分爆炸"现象,采用自适应律对模型未知参数进行在线估计,并利用非线性阻尼项克服外界干扰.通过Lyapunov方法证明得出闭环系统半全局一致稳定,跟踪误差可通过调节控制器参数达到任意小.仿真结果表明:该方法能在简化控制设计过程的同时保证航迹倾角跟踪上预定轨迹,控制系统具有较强的自适应能力且对外界干扰具有一定的鲁棒性.     

一种电离层场向不规则体各向异性散射模型

电离层场向不规则体散射具有很强的方向性, 利用电离层场向不规则体散 射进行VHF频段超视距通信时, 需要准确可靠地确定其散射分布特性及路径损 耗等参数. 基于电离层不规则体场向散射的特点, 以地球地磁场为坐标系统, 提出了一种电离层场向不规则体各向异性散射模型, 该模型能够计算前向和后 向散射链路的路径损耗分布、时延展宽和相干带宽等参数, 同时运用该模型对 雷达横向截面的计算结果与已有文献的数据结果进行对比, 证明了该模型的准确性. 该模型能够计算电离层场向不规则体VHF频段的散射分布及路径损耗等参数, 为VHF散射通信链路的设计、布站提供依据和技术指导.     

自抗扰控制技术在转台频响伺服中的应用

在转台频响伺服中,针对低频和低速时干扰难补偿、高频时相位滞后和幅值衰减程度急剧恶化、常规控制策略严重依赖精确对象模型等难题,引入不依赖精确对象模型的自抗扰控制技术,并设计了控制系统.控制系统中,自抗扰控制器用来在线观测补偿干扰,前置处理单元用来补偿相位和幅值.控制系统应用到转台频响伺服中,实测得到的"双十"标准下最大跟踪频率和扫频频率都大于转台出厂时的验收指标.实测结果表明:自抗扰控制技术应用到转台频响伺服中可以有效提升转台的频响性能.     

基于非正交干涉矩阵的飞机装配序列规划方法

针对飞机装配中外形曲面特征多、装配关系复杂、连接方式多样等带来的装配工艺设计问题,提出了一种基于非正交干涉矩阵的飞机部件装配序列规划方法.通过分析被装配零件的结构特点,增加非正交的装配坐标方向,构建了非正交干涉矩阵;给出了装配可行性的推导方法,实现了装配序列的自动生成.并以装配时间为目标函数,采用遗传算法对装配序列进行了优化.基于MATLAB仿真平台,对某型号飞机舱门装配过程进行了模拟.仿真结果表明,该方法简单易行.与传统的基于正交干涉矩阵的方法相比,对于可装配性和装配效率都有显著提高.     

充磁导致的超高速永磁同步电机不平衡磁拉力

转子永磁体充磁角度偏差导致的不平衡磁拉力对微型燃气轮机发电系统用超高速永磁同步电机的安全稳定运行有很大的影响.采用有限元数值分析方法,分别在不考虑转子偏心和考虑转子偏心的情况下,对由充磁角度偏差导致的超高速永磁同步电机不平衡磁拉力进行了计算和分析;将不平衡磁拉力的计算结果作为载荷,获得了超高速永磁同步电机空气轴承-转子系统的固有频率及振动特性.研究结果表明:转子系统在740 Hz附近发生共振,共振幅值随着转子磁芯充磁偏差角度的增大而增大;要保证转子系统安全可靠的工作,需要将磁芯的充磁角度偏差限制在5°以内.     

A straw-soil co-composting and evaluation for plant substrate in BLSS

Material closure is important for the establishment of Bioregenerative Life Support System, and many studies have focused on transforming candidate plant residues into plant culture medium. For the limitations of using wheat straw compost as substrate for plant cultivation, a straw-soil co-composting technique was studied. The changes of pH, C/N value, germination index, cellulose, lignin and so on were monitored during the co-composting process. The maturity was evaluated by the C/N value and the germination index. The result showed that after 45 days’ fermentation, the straw-soil final co-compost with inoculation (T1) became mature, while the co-compost without inoculation (T0) was not mature. In the plant culture test, the T1 substrate could satisfy the needs for lettuce’s growth, and the edible biomass yield of lettuce averaged 74.42 g pot⁻¹ at harvest. But the lettuces in T0 substrate showed stress symptoms and have not completed the growth cycle. Moreover, the results of nitrogen (N) transformation experiment showed that about 10.0% and 3.1% N were lost during the T1 co-composting and plant cultivation, respectively, 23.5% N was absorbed by lettuce, and 63.4% N remained in the T1 substrate after cultivation.     

基于资源相关性的网格资源分配

在网格环境中,每个网格服务都面临着多种资源选择,网格作业中各服务间的关联在某种程度上可映射为资源之间的依赖关系,不同的资源配置将产生不同的服务满意度,由此提出服务资源分配问题SRA(Service Resource Assignment),通过构造资源关系图提出基于树分解的资源分配算法DRA(Tree\|Decomposition based Resource Allocation algorithm),利用该算法求出此问题的正确消元顺序,在多项式时间复杂度内获得该问题的最优解,给出实验结果并提出下一步的研究工作.