Substitution of satellite-based land surface temperature defective data using GSP method

Land surface temperature (LST) as an important environmental variable provides valuable information for earth environmental system modelling. Currently, LST is obtained through satellite thermal sensors at various spatial and temporal resolutions. Although spatially continuous satellite-based LST measurements are intended to overcome the shortcomings of sparse ground-based LST measurements, LST images often contain anomalous values due to the existence of clouds or sensor malfunctioning. The problem becomes more serious where the users deal with high spatial resolution characterized by low temporal resolution. This study examines the capability of a newly developed graph signal processing (GSP) method using two-dimensional single-date thermal data. For this purpose, four Landsat/TIRS datasets are analyzed. The data of five elliptical regions on thermal images are eliminated and then reconstructed through the GSP method and using the LST values of the enclosing rectangles containing the ellipsoids. The results indicate that the temperature variation determined by the GSP method generally conforms to the original image LST values. According to a correlation test conducted on the original image LST and those obtained through the GSP method, the values vary from 58% to 95%, which is an above-the-average rate (RMSE from 0.69 to 2.27). The statistical analysis of the original image LST in both the elliptical regions and the enclosing rectangles containing the ellipsoids indicates that an increase in the variance of LST data causes an increased error in the calculation of temperature by the GSP method, and vice versa. The results of the analysis of variance (ANOVA) and Duncan test indicated that an increase in the number of the non-zero spectral bins would result in increased RMSE values for all the dates and the regions. Moreover, the model errors were significant at the 0.05 level across all the image date and five elliptical study regions. Based on the results, the use of this method is recommended for the reconstruction of LST missing values, where dissimilarity of atmospheric conditions limits the use of other methods that depend on the time series data of various dates and a great deal of data calculation.     

横航向驾驶员诱发振荡研究及地面模拟验证

本文建立了包括非线性环节在内的横航向驾驶员—操纵系统—飞机本体组合系统的数学模型,采用闭环控制原理,对JJ-7飞机横航向驾驶员诱发振荡PIO问题进行了研究,并详细地讨论了驾驶员参数及其各种操纵动作、操纵系统和飞机本体气动参数对横航向PIO的影响,探讨了横航向PIO产生的机理。文中以JJ-7飞机为例,采用时域法在整个飞行包线各点进行了检查,并用固基飞行模拟器进行模拟验证。其结果与理论计算结果相一致。     

Ту-154М变稳飞机空中飞行模拟试验评述

依据Ту－１５４М变稳飞机的特点，主要进行了不同操纵器、不同控制律和不同显示画面的飞行试验研究。特别是通过中央杆和侧杆、电传系统不同控制律飞行品质特性之间、两种先进控制方案及不同显示方式的比较，不仅掌握了这方面的试飞技术和评定技术，还亲身体验到变稳飞机在发展仿真技术，新机预研及提高试飞员试飞技术和评定技术等方面的巨大作用。     

VKM—5型立式捏合机研制与应用

介绍自行研制的VKM—5型立式捏合机的构造及工作原理,详述了该机采用液压传动和气动元件进行位置检测以及气、电、液安全联锁的特点,并说明与卧式捏合机对比试验情况。     

EUROPEAN NETWORK FOR THE NUMERICAL SIMULATION OF SPACE PLASMAS

The Cluster mission of the European Space Agency (ESA) will allow, for the first time three-dimensional measurements in key regions of the Earth's magnetosphere to be carried out. The European Numerical Simulation Network (ENSN) aims at providing a theoretical support to the mission. We describe the achievements of the ENSN during its first period of activity 1991–1994, during which the network was funded by the European Union. In particular, the ENSN has set up (i) thematic Working Groups on the prime scientific goals of the mission, (ii) a code development Working Group to develop numerical simulation codes specifically adapted to studying magnetospheric boundaries and the corresponding scale mixing, and (iii) software models of Cluster instruments to test in a numerical simulation what the set of four instruments will measure.     

激光外差干涉仪光电信号处理方法及特点

叙述和分析了外差激光干涉光电信号处理主其特点，指出了它们各自的应用范围，同时介绍了一处新型的光电信号处理方法，它不仅使外差干涉仪用于动态测量，而且可以同时实现高分辩率测量 。     

掠海飞行导弹击水概率的仿真研究

本文对掠海导弹的击水概率问题进行了研究,提出了用均匀设计、Monte—Carlo法和逐步回归法建立击水概率预报公式的仿真方法,并结合某型号的反舰导弹进行计算,得到了满意的结果。本文还利用表观频率和表观频谱的概念,建立起飞航导弹的背景干扰——海浪和阵风的数学模型,并用波叠加法进行了数字仿真。     

频率及频率变化率的快速最大似然估计

信号参数估计是许多领域 (如雷达、通信、导航和声钠等 )都会遇到的共同问题。文中证明 ,牛顿法是实现频率 (η)和频率变化 (β)最大似然估值器的快速有效算法 ,并且详细分析了牛顿估值器的性能。研究证明 ,对于牛顿法 ,(η,β)是以三次方律收敛于真值 (η,β)的。模拟结果表明 ,当输出信噪比 ( SNR) o≥ 15 d B时 ,估计量的均方误差 ( MSE)达到Cramer- Rao界     

基于TMS320C80的BP算法并行实现的研究

结合 TMS32 0 C80的编程结构 ,利用神经网络的权并行性和神经元并行性 ,提出了BP算法的并行实现方法 ,并解决了存储器访问冲突、数据双缓冲传输、PP细粒度并行和死锁等问题。结果表明 ,该并行 BP算法十分有效。     

利用遥测数据预报导弹落点的方法

给出利用遥测数据对导弹进行落点预报的方法。根据遥测数据传输多遍的特点，对解码后的ＰＣＭ 数据进行处理，得到误码率很小的数据。然后对头体分离时刻前导弹飞行的状况和遥测数据进行分析，从而对发动机后效误差进行修正，得到较精确的导弹运动参数，最后利用弹道方程预报导弹落点