Bidirectional NDVI and atmospherically resistant BRDF inversion for vegetation canopy

The normalized difference vegetation index (NDVI) has been widely applied in optical remote sensing. However, it has been demonstrated that NDVI is still partially affected by atmospheric path scattering and bidirectional (illumination and viewing geometry) effects. In this paper we present the benefit of using a bidirectional NDVI, and we discuss the problems in using the maximum NDVI composite method. Based on the assumption that a clear day has a larger NDVI value and a cloudy day has a smaller NDVI value (smaller reflectance in the near-infrared band and larger reflectance in red band due to atmospheric path scattering), the ratio of squared observed NDVI values and calculated NDVI values is used as a weight in our inversion method. The calculated NDVI values are derived from previously inverted bidirectional reflectance distribution functions (BRDFs). The inversion process will loop until all weights converge. Our research on the early Terra/MODIS data using a semiempirical kernel-driven BRDF model (the RossThick-LiTransit model) shows that this new method can improve inversion results whenever some cloudy pixels are not filtered out. As cloud detection and subpixel cloudiness are always a problem, this technique should still be very useful in improving the quality of BRDF inversion.     

宽频段太赫兹辐射计高吸收率涂层的特性

为了对宽频段高吸收率太赫兹辐射计的特性进行表征,研究了吸收涂层材料的特性;对常见的吸波材料在太赫兹波段的吸收率进行仿真,探寻在太赫兹波段具有高吸收率的材料;将碳化硅与3M黑漆进行混合,以进一步提高涂层的吸收率,并通过仿真调整涂层内碳化硅颗粒的尺寸;根据仿真结果制备混合涂层,利用太赫兹时域光谱仪对混合涂层样品进行测量。结果表明:该混合涂层样品的光谱吸收率大于0.99,与仿真结果基本吻合。     

数字化医院网络平台建设研究

数字化医院是我国现代医疗发展的趋势,是医院业务软件、数字化医疗设备、网络平台组成的三位一体的综合信息系统,可以有效实现医院资源整合、流程优化,进一步提高医疗服务质量、工作效率和管理水平,而网络平台是数字化医院建设中重要组成部分和通信链路支撑。文章通过研究数字化医院数据流量模型特征,分析医院网络架构要求,引入基于网络虚拟化的新型网络系统和安全域策略,实现网络资源的灵活调度,更好的适应未来数字医疗领域的多业务发展。     

带有热沉结构的全镂空光读出红外焦平面阵列

A substrate-free optical readout focal plane array(FPA) operating in 8-12μm with a heat sink structure (HSS) was fabricated and its performance was tested.The temperature distribution of the FPA with an HSS investigated by using a commercial FLIR IR camera shows excellent uniformity.The thermal cross-talk effect existing in traditional substrate-free FPAs was eliminated effectively.The heat sink is fabricated successfully by electroplating copper,which provides high thermal capacity and high thermal conductivity,on the frame of substrate-free FPA. The FPA was tested in the optical-readout system,the results show that the response and NETD are 13.6 grey/K(F / # = 0.8) and 588 mK,respectively.     

新型莫来石瓷在高密度封装中的应用

描述了低介电常数，低膨胀系数新型莫来石瓷在高密度封装中的应用，从设计考虑、封装结构、工艺及电性能方面进行了探讨，以期获得满足高速、超高速集成电路使用要求的高性能封装。     

一种新型C波段宽带圆极化贴片天线的设计

采用电磁仿真计算软件HFSS设计并仿真了一种工作于C波段宽带圆极化微带贴片天线。天线采用双馈点对圆形微带贴片进行馈电,实现圆极化;选用两层聚四氟乙烯玻璃纤维板作为介质,通过底层馈电网络由探针穿过中间地板层对上层圆形贴片进行馈电,在探针周围用环形槽将探针与地板进行隔离,并增加了天线的谐振点,从而进一步扩展了天线频带。结果表明天线的相对带宽约为30％,并且E面、H面3dB轴比角度均大于90°。     

声光双稳系统周期微扰反馈混沌控制研究

利用周期微扰反馈的方法,数值研究了声光双稳系统的混沌控制,通过对混沌态施加一定幅值和频率的周期微扰信号,可以将混沌态控制到不动点和周期轨道上。并用实验证明了这种方法的有效性。     

四川盆地中国石化探区须家河组致密砂岩气勘探开发进展与攻关方向

四川盆地须家河组致密砂岩气的勘探取得了丰硕的成果,但是气藏整体表现为"储层致密、大面积含气、局部富集"的特点,开发生产中普遍呈现出储量丰度低、普遍产水和裂缝控产等特征,储量动用难度大.近年来,以有效建产和高效勘探为主要目标,应用地质-工程一体化的思路,开展了四川盆地中国石化探区须家河组的新一轮勘探开发攻关研究,在基础地...