GPS双频精密单点定位软件及其精度分析

简要介绍了GPS双频精密单点定位数学模型及自主研制的精密单点定位软件。采用不同运动状态的实测数据进行静态、静态模拟动态和机载动态解算实验并从外符合的角度进行精度评估。实验结果表明:单天静态解精度达到cm级;动态解算精度达到cm-dm级。     

SUSTAINABLE AGRICULTURE DEVELOPMENT IN SALINE—ALKALI SOIL AREA OF SONGNEN PLAIN, NORTHEAST CHINA NORTHEAST CHINA

There is great potential for agriculture in saline-alkali soil area in Songnen Plain, Northeast China. Butthe sustainable crop production in this area has been restricted by a few of main factors, such as less precipitation, higherevaporation and frequent drought, high salinity and alkalinity, high exchangeable sodium content and poor infiltration ofthe soil, and insufficiency and low availability in nutrition. It is also considered that there are a few of favorable condi-tions for agricultural development in this region, such as sufficient light and heat resources, rich ground water resources,plenty of manure produced by livestock, and so on. At the same time, scientific management and measurements havebeen employed; rational irrigation and drainage system has been established; reclamation, amendment and fertilization ofsoil, and suitable strategies of cropping practices have been made for the sustainable development of agriculture. Great progress has been made during 1996- 2000.     

SUTDY ON THE FRAMEWORK SYSTEM OF DIGITAL AGRICULTURE

China is a great agricultural country with large population,limited soil resources and traditional farming mode,so the central government has been attaching great importance to the development of agriculture and put forward a new agricultural technology revolution-the transformation from traditional agricultrure to modern agriculture and from exten-sive farming to intensive farming,Digital agriculture is the core of agricultural informatization.The enforcement of digital agriculture will greatly promote agricultural technology revolution.two agricultural transformations and its rapid develop-ment,and enhance China‘s competitive power after the entrance of WTO.To carry out digital agriculture,the frame sys-tem of digital agriculture is required to be studied in the first place,In accordance with the theory and technology of digi-tal earth and in combination with the agricultural reality of China,this artile outlines the frame system of digital agricul-ture and its main content and technology support.     

湛江农业剩余劳动力转移的方向及对策

从湛江农业劳动力现状出发 ,估算了农业剩余劳动力数量 ,分析了农业剩余劳动力转移中的障碍 ,提出湛江农业剩余劳动力转移的方向和政策建议。     

GPS和电子水准仪在烟台控制网中的应用

采用全球卫星定位系统GPS施测了三等控制网，作为首级平面控制网。为提高观测速度、精度和可靠性，采用DL-102C电子水准仪建立了三等水准网作为首级高程控制网，用三等水准联测过的GPS控制点作为起算点进行GPS高程拟合。三等GPS网的总点数为57个，联测国家二等三角点4个，利用旧点9个，新布设GPS控制点44个，平均边长2．46km，控制面积约350km^2，在1980西安坐标系下进行平差，同时在烟台城市坐标系下平差计算，使开发区与城市建成区的控制网能够紧密地联系起来。三等水准网的总点数为41个，起算点为2个国家一等水准点，往返测水准路线总长为203．4km。平面精度和高程拟合精度均达到了国家规定的指标要求。     

新疆农业景观格局演变对其生态系统服务价值的影响

结合遥感、地理信息系统、景观生态学和空间分析等理论,分析了新疆地区2000~2015年农业景观格局的时空动态变化特征,测算了农业生态系统服务价值,通过相关分析进一步研究了农业景观格局与生态系统服务价值的关联,为促进区域土地资源合理利用和生态农业发展提供科学依据。结果表明,新疆农业生态系统正朝着多样化、稳定化的方向发展;农业生态系统服务价值显著增长,但区域间的价值差异较大,呈现北疆高南疆低的分布格局;景观面积、斑块数和景观形状对新疆地区农业生态系统服务价值影响较大且均呈现明显正相关关系。     

我国林业地理信息产业发展与创新

林业地理信息,是以森林资源及生态环境为研究对象,依托现代地球观测、大数据、物联网、云计算等先进技术,通过精准的时空观测,实施精准的时空作业,达到理想林业时空模式,从而使森林最大限度地发挥生态效益、社会效益和经济效益。林业地理信息主要应用在森林观测、森林经营、造林、森林灾害防控方面。本文从林业地理信息特征、林业地理信息产业需求和林业地理信息装备创新3个方面对林业地理信息进行阐述。     

基于1∶10000地形数据更新1∶50000 DEM的研究试验

对1:50 000 DEM数据库的现状进行了分析,提出了利用1:10 000地形数据更新1:50 000 DEM的主要内容和两种方法,简要介绍了地形变化检测方法。通过对试验区规则格网DEM成果的精度检查验证了方法的可行性。客观分析了本次试验的特点和不足,为以后大比例尺地形数据更新小比例尺DEM等相关工作提供了技术参考。     

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