Landsat 8地表温度产品验证与分析

Landsat系列卫星热波段具有60~120m的空间分辨率,对各种环境监测起到了重要的作用。随着Landsat系列卫星在全球范围内地表温度（land surface temperature,LST）产品的发布,其验证工作也随之展开,然而对于长时间序列的精度验证工作仍然缺乏。以黑河流域中游为研究区,利用研究区内湿地站（SD）、戈壁站（GB）和大满超级站（CJZ）三个气象站的地面测量数据对2013-2016年清晰无云的31景Landsat 8地表温度产品进行了验证与分析,并将Landsat 8地表温度产品与广泛使用的普适性单通道算法（JMS）反演结果进行了对比。结果表明,Landsat 8地表温度产品与普适性单通道算法反演结果精度均较高,在各个站点处R2均优于0.949。基于所有站点分析,Landsat 8地表温度产品精度稍高于普适性单通道算法反演结果。     

基于五光谱TDICCD的模拟信号发生器设计

首先介绍了延迟积分电荷耦合器件（TDICCD）的基本原理,并根据某高分辨率多光谱航天相机定制的一款五光谱TDICCD的输出特性,设计了一种基于五光谱TDICCD的模拟信号发生器,给出了该模拟信号发生器的系统组成,包括图像处理电路、数模转换电路和模拟信号滤波电路。最后通过测试验证了该系统的信号波形、信号噪声和输出图像都满足设计要求,其输出的16通道模拟五光谱TDICCD信号频率可以达到20MHz,噪声控制在10mV以内,具有高精度、多通道和低噪声等特点。目前该模拟信号发生器已成功应用到新一代高分辨率多光谱TDICCD相机成像电路系统的研制中。     

Semi-global leader-following consensus-based formation flight of unmanned aerial vehicles

In this paper, we investigate a formation control problem of multi-agent systems(specifically a group of unmanned aerial vehicles) based on a semi-global leader-following consensus approach with both the leader and the followers subject to input saturation. Utilizing the low gain feedback design technique, a distributed static control protocol and a distributed adaptive control protocol are constructed. The former solves the problem under an assumption that the communication network is undirecte...     

Towards a Global Unified Model of Europa’s Tenuous Atmosphere

Despite the numerous modeling efforts of the past, our knowledge on the radiation-induced physical and chemical processes in Europa’s tenuous atmosphere and on the exchange of material between the moon’s surface and Jupiter’s magnetosphere remains limited. In lack of an adequate number of in situ observations, the existence of a wide variety of models based on different scenarios and considerations has resulted in a fragmentary understanding of the interactions of the magnetospheric ion population with both the moon’s icy surface and neutral gas envelope. Models show large discrepancy in the source and loss rates of the different constituents as well as in the determination of the spatial distribution of the atmosphere and its variation with time. The existence of several models based on very different approaches highlights the need of a detailed comparison among them with the final goal of developing a unified model of Europa’s tenuous atmosphere. The availability to the science community of such a model could be of particular interest in view of the planning of the future mission observations (e.g., ESA’s JUpiter ICy moons Explorer (JUICE) mission, and NASA’s Europa Clipper mission). We review the existing models of Europa’s tenuous atmosphere and discuss each of their derived characteristics of the neutral environment. We also discuss discrepancies among different models and the assumptions of the plasma environment in the vicinity of Europa. A summary of the existing observations of both the neutral and the plasma environments at Europa is also presented. The characteristics of a global unified model of the tenuous atmosphere are, then, discussed. Finally, we identify needed future experimental work in laboratories and propose some suitable observation strategies for upcoming missions.     

航空发动机故障诊断方程的求解及应用

用换算系数方法建立了基线模型，分析了测量参数偏差的计算方法，重点介绍了发动机故障诊断系统中故障方程的求解方法，并应用发动机试车数据对此进行了求解检验，结果表明故障诊断方程的求解方法可行。     

某航空涡轴发动机健康状况监视与分析

为了及时掌握某涡轴发动机的健康状况，设计了机载发动机参数监视仪，发动机的热力参数，滑油参数及振动参数进行了监视，编制了地面分析软件，给出了用于诊断发动机单元体故障的测量参数和部件性能评估参数，探讨了利用故障因子概念诊断单元体故障的方法，运用发动机的实际无故障数据和模拟故障数据进行了仿真，结果表明，诊断结论可信，该系统在对役涡轴发动机的健康监视具有实用性。     

进气温度与压力对涡流管性能影响的实验

实验研究了涡流管进出口膨胀比(2~5)、节流阀开度(1~11)和进气温度(313~373K)对涡流管性能的影响,重点分析了制冷和制热温度效应随上述参数的变化规律.研究中发现:随着进口膨胀比增加,管内涡流强度增强,不同半径处气流的角速度梯度增大,涡流制冷温度效应增强10.9%,制热温度效应增强46.5%.随着节流阀开度增加,冷/热气流之间能量交换的程度提升,涡流效应增强,冷流率增大47.3%.随着进气温度增加,涡轮管性能逐步提升.实验结果表明:进气温度每增加20K,制冷温度效应平均增幅约为12%,制热温度效应平均增幅约为5%.