三轴稳定卫星的星敏感器对地定姿精度分析

给出利用星敏感器进行惯性姿态和对地姿态确定的流程,重点分析了惯性姿态向对地姿态转换过程中的误差传播关系,给出了相应的误差传播矩阵和误差传播影响因子。仿真表明,由于坐标转换时引入轨道参数误差,误差传播影响因子一般在1~2之间,因而使得对地定姿精度较惯性定姿精度稍低。     

大型网状可展开天线模态分析

利用ANSYS软件,建立了某大型网状可展开天线展开和收拢状态模态分析的有限元计算模型．给出了展开和收拢状态下天线结构所对应的固有频率和振型。     

基于AR模型对滑油中金属元素含量的预测

利用时间序列分析方法对某型航空发动机滑油监控系统中需重点监控的金属元素含量建立了AR模型。并根据该模型对其含量变化趋势进行了预测分析。某部队通过对不同实测数据的检验证明，可根据该模型的预测结果预报金属含量是否招标。     

不同温度下丁羟包覆层的横向弛豫时间与拉伸性能的相关性

为了研究不同温度下丁羟包覆层的横向弛豫时间与拉伸性能的相关性,开展了核磁共振和拉伸应力-应变性能测定试验。单因素方差分析表明温度对横向弛豫时间有显著影响;试验温度从30℃升到90℃,横向弛豫时间呈线性增大;90℃升到130℃,横向弛豫时间先减小后增大。30～90℃,升温使包覆层的拉伸强度下降,断裂伸长率升高;在100℃较90℃强度得到了提高,断裂伸长率稍有降低;在100～130℃时,受复杂化学反应和分子热运动共同影响,断裂伸长率迅速增加,强度降低。断裂伸长率、拉伸强度均与横向弛豫时间存在较好的相关性,利用该关系可以预测丁羟包覆层在不同横向弛豫时间下的拉伸性能。     

考虑钉头传载的阶梯搭接钉载分配特性

确定钉载分配比例是机械连接强度分析的基础和关键,也是研究孔周应力分布的前提。以某型飞机铝合金阶梯形搭接板螺栓群连接结构为研究对象,利用应变电测法初步测量了各排螺栓的钉载分配比例。随后通过ABAQUS有限元三维实体建模,考虑钉头传载及接触摩擦、螺栓预紧、材料非线性、防弯夹具等因素,对螺栓群的钉载分配行为进行了模拟。计算发现：阶梯形搭接板多钉连接的钉载分配比例呈两端大中间小的规律,且台阶高度是影响钉载分配比例的重要因素。在此基础上,进一步研究了台阶高度对钉载分配均匀性的影响。分析结果表明：阶梯形搭接板多钉连接处于弹性范围以内时,随着台阶高度的增加,钉载分配趋于均匀;结构产生塑性变形后,随着台阶高度的增加,钉载分配先趋于均匀后随之变差。最后,基于钉载分配与孔边最大应力,对阶梯搭接多钉连接的几何构型进行了优化。优化后阶梯搭接的钉载分配比例极差不超过1.1%,最危险部位的孔边最大应力及螺栓最大剪切应力分别减小了约4.4%与10.2%。     

随机振动载荷下连接螺栓振动疲劳强度分析

通过有限元分析计算出连接螺栓上的载荷,理论计算得出连接螺栓上的1 振动应力,基于高斯分布和线性累计损伤定律的三区间法,结合材料的S-N曲线,对连接螺栓进行随机振动载荷下的振动疲劳强度进行评估。     

多传感器遥感图像数据融合研究

重点研究了卫星遥感图像融合技术.通过在Matlab平台上实现基于颜色空间变换和基于小波变换的图像融合算法,分析了颜色空间变换的融合特点,并结合高分辨率图像、多光谱图像以及SAR图像的融合结果对相关理论进行了验证;研究了基于小波变换的融合方法在不同分解和重构级数下所获得的融合图像的特征,比较了各级融合图像的特点和相互间的差别;通过对高分辨率图像和多光谱图像的融合实例,给出了达到融合目的所应进行的最低分解重构级数与两原始图像空间分辨率指标比值间的定量关系;分析了不同小波因子对融合结果的影响,并结合颜色空间变换方法的融合结果得出了最终结论.      

资料转移技术在三维有限元中的应用

本文研究了两类用于三维h自适应网络管理的资料转移方法。文中将牺牲解的精度以节省计算时间的一类资料转移的简单方法（简法）与另一类在资料转移中确保解决的精度的严格方法（严法）进行了比较分析，并通过数值计算例题进行了论证，结果表明：对于简单问题，两类方法都能满足精度，完成资料转移。对于复杂应力状态问题，严法可靠，特别是在网络稀疏时，严法明显优越。     

基于自组织神经网络的空中交通复杂度参数优化及预测

首先介绍了国内外关于空中交通复杂度的定义及研究现状。然后在现有的空中交通复杂度模型中挑选空中交通复杂度参数,再利用自组织神经网络,分析所选取的空中交通复杂度参数之间的关系,达到将高维空中交通复杂度参数进行降维分析的目的。然后对于优化了的空中交通复杂度参数使用RBF神经网络进行预测,比较预测结果,得到最优的空中交通复杂度参数。     

Contribution analysis of QZSS to single-frequency PPP of GPS/BDS/GLONASS/Galileo

The Quasi-Zenith Satellite System (QZSS) established by the Japan Aerospace Exploration Agency mainly serves the Asia-Pacific region and its surrounding areas. Currently, four in-orbit satellites provide services. Most users of GNSS in the mass market use single-frequency (SF) receivers owing to the low cost. Therefore, it is meaningful to analyze and evaluate the contribution of the QZSS to SF precise point positioning (PPP) of GPS/BDS/GLONASS/Galileo systems with the emergence of GNSS and QZSS. This study compares the performances of three SF PPP models, namely the GRoup and PHase Ionospheric Correction (GRAPHIC) model, GRAPHIC with code observation model, and an ionosphere-constrained model, and evaluated the contribution of the QZSS to the SF PPP of GPS/BDS/GLONASS/Galileo systems. Moreover, the influence of code bias on the SF PPP of the BDS system is also analyzed. A two-week dataset (DOY 013–026, 2019) from 10 stations of the MGEX network is selected for validation, and the results show that: (1) For cut-off elevation angles of 15, 20, and 25°, the convergence times for the static SF PPP of GLONASS + QZSS are reduced by 4.3, 30.8, and 12.7%, respectively, and the positioning accuracy is similar compared with that of the GLONASS system. Compared with the BDS single system, the convergence times for the static SF PPP of BDS + QZSS under 15 and 25° are reduced by 37.6 and 39.2%, the horizontal positioning accuracies are improved by 18.6 and 14.1%, and the vertical components are improved by 13.9 and 21.4%, respectively. At cut-off elevation angles of 15, 20, and 25°, the positioning accuracy and precision of GPS/BDS/GLONASS/Galileo + QZSS is similar to that of GPS/BDS/GLONASS/Galileo. And the convergence times are reduced by 7.4 and 4.3% at cut-off elevation angles of 20 and 25°, respectively. In imitating dynamic PPP, the QZSS significantly improves the positioning accuracy of BDS and GLONASS. However, QZSS has little effect on the GPS-only, Galileo-only and GPS/BDS/GLONASS/Galileo. (2) The code bias of BDS IGSO and MEO cannot be ignored in SF PPP. In static SF PPP, taking the frequency band of B1I whose multipath combination is the largest among the frequency bands as an example, the vertical component has a systematic bias of approximately 0.4–1.0 m. After correcting the code bias, the positioning error in the vertical component is lower than 0.2 m, and the positioning accuracy in the horizontal component are improved accordingly. (3) The SF PPP model with ionosphere constraints has a better convergence speed, while the positioning accuracy of the three models is nearly equal. Therefore the GRAPHIC model can be used to get good positioning accuracy in the absence of external ionosphere products, but its convergence speed is slower.