卫星系统研制过程活劳动消耗模型研究

本文分析了科技研制活劳动消耗的特点,对影响卫星系统研制活劳动消耗量的因素进行了分析和量化,探讨了各影响因素系数修正的方法,在此基础上,建立一系列卫星系统研制过程分阶段、分系统、分工作类型和承担单位的活劳动消耗预测模型。     

小型卫星接收系统的几个问题

本文论述卫星接收品质、小型卫星接收系统构成及技术，为建立小型卫星地面接收站提供理论依据。     

QuickBird卫星影像处理技术实践

采用卫星遥感方法制作的数字正射影像是获取基础空间信息最快速、高效的手段,利用高精度卫星遥感成图,处理速度快、工艺简便、图像清晰,而且精度达到成图要求。本文重点介绍以QuickBird0.6米全色和2.4米多光谱为数据源,制作DOM的技术要求、方法、工艺流程和质量控制指标。     

An improved in-situ bio-optical data set for ocean color algorithm development and satellite data product validation

Global satellite ocean color instruments provide the scientific community a high-resolution means of studying the marine biosphere. Satellite data product validation and algorithm development activities both require the substantial accumulation of high-quality in-situ observations. The NASA Ocean Biology Processing Group maintains a local repository of in-situ marine bio-optical data, the SeaWiFS Bio-optical Archive and Storage System (SeaBASS), to facilitate their ocean color satellite validation analyses. Data were acquired from SeaBASS and used to compile a large set of coincident radiometric observations and phytoplankton pigment concentrations for use in bio-optical algorithm development. This new data set, the NASA bio-Optical Marine Algorithm Data set (NOMAD), includes over 3400 stations of spectral water-leaving radiances, surface irradiances, and diffuse downwelling attenuation coefficients, encompassing chlorophyll a concentrations ranging from 0.012 to 72.12 mg m^− 3. Metadata, such as the date, time, and location of data collection, and ancillary data, including sea surface temperatures and water depths, accompany each record. This paper describes the assembly and evaluation of NOMAD, and further illustrates the broad geophysical range of stations incorporated into NOMAD.     

Spectral Network (SpecNet)—What is it and why do we need it?

Effective integration of optical remote sensing with flux measurements across multiple scales is essential for understanding global patterns of surface-atmosphere fluxes of carbon and water vapor. SpecNet (Spectral Network) is an international network of cooperating investigators and sites linking optical measurements with flux sampling for the purpose of improving our understanding of the controls on these fluxes. An additional goal is to characterize disturbance impacts on surface-atmosphere fluxes. To reach these goals, key SpecNet objectives include the exploration of scaling issues, development of novel sampling tools, standardization and intercomparison of sampling methods, development of models and statistical methods that relate optical sampling to fluxes, exploration of component fluxes, validation of satellite products, and development of an informatics approach that integrates disparate data sources across scales. Examples of these themes are summarized in this review.     

基于模板的图像特技显示方法的研究与实现

随着计算机软硬技术的发展,多媒体计算机(MPC)应用日益广泛。在多媒体计算机应用中,图形图像处理占有主要的地位。图像显示是图像处理的基础,特技显示的关键是把图像划分成不同的图像区域块,通常的图像特技显示方法是把图像按一定的规则划分成不同的图像块。该文在分析图像特技显示的原理基础上,提出了基于模板的图像特技显示方法。这种方法突破了传统的图像特技显示方法把图像按规则划分的限制,通过模板图像和变换层次参数的设定,可以根据软件用户的爱好任意设置图像的特技显示方式。实践证明,这种方法在实际图像处理软件和多媒体软件设计中有极大的应用价值。     

馈源阵面排列对偏置多波束天线特性的影响

以３７单元馈源阵为例,就用于卫星移动通信系统中的偏置多波束天线进行分析探讨：在原有两种馈源阵阵面排列形式的基础上,又提出了第三种排列形式,即馈源阵的球面排列形式,并对这三种形式下偏置多波束天线的远场特征进行了计算比较,得出了一些有益的结论;另外,将馈源阵阵面适当地偏离焦点也可使多波束天线的远场特性得以改善。     

SpaceWire总线在遥感卫星数传系统中的设计应用

SpaceWire总线是一种面向航天应用的基于LVDS串行传输的新型技术,解决了目前数据传输系统的总线带宽不足问题,并提供一种通用接口标准以简化和规范异种设备之间的互连.文章介绍了SpaceWire总线的技术特点,并对该总线在某型号卫星数传系统中的设计应用进行了分析和研究.     

Spatial, spectral and temporal patterns of tropical forest cover change as observed with multiple scales of optical satellite data

This article describes the development of a methodology for scaling observations of changes in tropical forest cover to large areas at high temporal frequency from coarse resolution satellite imagery. The approach for estimating proportional forest cover change as a continuous variable is based on a regression model that relates multispectral, multitemporal MODIS data, transformed to optimize the spectral detection of vegetation changes, to reference change data sets derived from a Landsat data record for a study site in Central America. A number of issues involved in model development are addressed here by exploring the spatial, spectral and temporal patterns of forest cover change as manifested in a time-series of multi-scale satellite imagery.The analyses highlighted the distinct spectral change patterns from year-to-year in response to the possible land cover trajectories of forest clearing, regeneration and changes in climatic and land cover conditions. Spectral response in the MODIS Calibrated Radiances Swath data set followed more closely with the expected patterns of forest cover change than did the spectral response in the Gridded Surface Reflectance product. With forest cover change patterns relatively invariant to the spatial grain size of the analysis, the model results indicate that the best spectral metrics for detecting tropical forest clearing and regeneration are those that incorporate shortwave infrared information from the MODIS calibrated radiances data set at 500-m resolution, with errors ranging from 7.4 to 10.9% across the time periods of analysis.