This paper investigates the problem of almanac affecting the signal acquisition time with two constraints: different age of data and multi-sets of almanac. The contributions made in this paper include: 1) the exploiti...This paper investigates the problem of almanac affecting the signal acquisition time with two constraints: different age of data and multi-sets of almanac. The contributions made in this paper include: 1) the exploiting of signal acquisition concept to extend well-known almanac function of predicting visible satellite and initializing signal acquisition to minimizing the signal acquisition time; 2) a model based on code phase and Doppler frequency to reflect the impact of multi-sets of almanac on the signal acquisition time; 3) the evaluation of the existing GPS almanac with different broadcast strategy. The theoretical analyses and simulations conducted on three sets of almanac show that the model proposed in this paper is general and efficient for almanac design and application.展开更多
Water quality modeling requires across-scale support of combined digital soil elements and simulation parameters. This paper presents the unprecedented development of a large spatial scale (1:250,000) ArcGIS geodataba...Water quality modeling requires across-scale support of combined digital soil elements and simulation parameters. This paper presents the unprecedented development of a large spatial scale (1:250,000) ArcGIS geodatabase coverage designed as a functional repository of soil-parameters for modeling and comparison of water quality outcomes in the United States. The set of target models include: SWAT (Soil and Water Assessment Tool), APEX (Agricultural Policy Environmental Extender), and ALMANAC (Agricultural Land Management Alternatives with Numerical Assessment Criteria). This development relies on the Digital General Soil Map (DGSM) as the source of soil information, and leverages on architectural design and associated tools created for a companion product at higher resolution from which also was extended a procedure for refilling a large number of missing derived parameters. Outlined by regional watershed layouts and supported by GIS land use layers, the core product is developed using the File Geodatabase (FGDB) data structure, which brings, via customized Python-based tools, the data directly into geoprocessing workflows. The FGDB implement efficiently stores spatial soil features, tabular model elements and linked relationships, while seamlessly providing the environment for the extraction, spatial analysis, and mapping of the models’ parameters. As an alternative, the composing spatial elements, polygons and multi-resolution rasters, and the models’ elements are offered as a file-folder system of data with completely Open Source formats. Finally, this geographic database coverage provides support for the traditional large-scale and harmonized application of the models as well as an alternative to the higher resolution companion for areas where this information is still under development.展开更多
Accurate crop growth monitoring and yield forecasting have important implications for food security and agricultural macro-control. Crop simulation and satellite remote sensing have their own advantages, combining the...Accurate crop growth monitoring and yield forecasting have important implications for food security and agricultural macro-control. Crop simulation and satellite remote sensing have their own advantages, combining the two can improve the real-time mechanism and accuracy of agricultural monitoring and evaluation. The research is based on the MERSI data carried by China’s new generation Fengyun-3 meteorological satellite, combined with the US ALMANAC crop model, established the NDVI-LAI model and realized the acquisition of LAI data from point to surface. Because of the principle of the relationship between the morphological changes of LAI curve and the growth of crops, an index that can be used to determine the growth of crops is established to realize real-time, dynamic and wide-scale monitoring of winter wheat growth. At the same time, the index was used to select the different key growth stages of winter wheat for yield estimation. The results showed that the relative error of total yield during the filling period was low, nearly 5%. The research results show that the combination of domestic meteorological satellite Fengyun-3 and ALMANAC crop model for crop growth monitoring and yield estimation is feasible, and further expands the application range of domestic satellites.展开更多
《上海年鉴(1854)》是North China Herald(《北华捷报》)出版的第三本《上海年鉴》。虽然书名“Shanhae Almanac for 1854”,但详析Almanac一词源流,该词实际上包含了历书以外的内容,故应译作“上海年鉴”而非“上海历书”。Almanac既...《上海年鉴(1854)》是North China Herald(《北华捷报》)出版的第三本《上海年鉴》。虽然书名“Shanhae Almanac for 1854”,但详析Almanac一词源流,该词实际上包含了历书以外的内容,故应译作“上海年鉴”而非“上海历书”。Almanac既然兼有年鉴与历书两义,就必定与某一文化或某一地域相关连。通过搜集整理早期上海地区中西文报章杂志与书刊中发布出来的有关租界以及上海城市的信息,从这些海量信息中分析观察开埠以来上海城市的近代化进程,从1850年到20世纪上海城市面貌的变迁,这是一件极其有意义的事。但是近代文献散佚严重,这些珍贵的信息文献资料往往不可得。不久前上海图书馆购入的罗氏藏书中有1854年上海年鉴是十分珍贵的典籍。据高第同书目所载该年鉴有1852年到1863年(其中1859与1862两年未见)十种,是一个系列的书,但今天已不能得其全。连续出版的《上海年鉴》对于研究和观察开埠以后上海面貌的逐年变化情况,无疑是极其有用的史料。《上海年鉴》如此珍稀,值得我们认真研究。同时,《〈上海年鉴(1854)〉研究》就是对目前可见的最早的一本《上海年鉴》内容的全面介绍与分析,希望能有助于读者一窥上海开埠初期的上海城市面貌。展开更多
基金Sponsored by the National Basic Research Program of China(Grant No.2010CB731800)the National Natural Science Foundation of China(GrantNo.60879012/F01)
文摘This paper investigates the problem of almanac affecting the signal acquisition time with two constraints: different age of data and multi-sets of almanac. The contributions made in this paper include: 1) the exploiting of signal acquisition concept to extend well-known almanac function of predicting visible satellite and initializing signal acquisition to minimizing the signal acquisition time; 2) a model based on code phase and Doppler frequency to reflect the impact of multi-sets of almanac on the signal acquisition time; 3) the evaluation of the existing GPS almanac with different broadcast strategy. The theoretical analyses and simulations conducted on three sets of almanac show that the model proposed in this paper is general and efficient for almanac design and application.
文摘Water quality modeling requires across-scale support of combined digital soil elements and simulation parameters. This paper presents the unprecedented development of a large spatial scale (1:250,000) ArcGIS geodatabase coverage designed as a functional repository of soil-parameters for modeling and comparison of water quality outcomes in the United States. The set of target models include: SWAT (Soil and Water Assessment Tool), APEX (Agricultural Policy Environmental Extender), and ALMANAC (Agricultural Land Management Alternatives with Numerical Assessment Criteria). This development relies on the Digital General Soil Map (DGSM) as the source of soil information, and leverages on architectural design and associated tools created for a companion product at higher resolution from which also was extended a procedure for refilling a large number of missing derived parameters. Outlined by regional watershed layouts and supported by GIS land use layers, the core product is developed using the File Geodatabase (FGDB) data structure, which brings, via customized Python-based tools, the data directly into geoprocessing workflows. The FGDB implement efficiently stores spatial soil features, tabular model elements and linked relationships, while seamlessly providing the environment for the extraction, spatial analysis, and mapping of the models’ parameters. As an alternative, the composing spatial elements, polygons and multi-resolution rasters, and the models’ elements are offered as a file-folder system of data with completely Open Source formats. Finally, this geographic database coverage provides support for the traditional large-scale and harmonized application of the models as well as an alternative to the higher resolution companion for areas where this information is still under development.
文摘Accurate crop growth monitoring and yield forecasting have important implications for food security and agricultural macro-control. Crop simulation and satellite remote sensing have their own advantages, combining the two can improve the real-time mechanism and accuracy of agricultural monitoring and evaluation. The research is based on the MERSI data carried by China’s new generation Fengyun-3 meteorological satellite, combined with the US ALMANAC crop model, established the NDVI-LAI model and realized the acquisition of LAI data from point to surface. Because of the principle of the relationship between the morphological changes of LAI curve and the growth of crops, an index that can be used to determine the growth of crops is established to realize real-time, dynamic and wide-scale monitoring of winter wheat growth. At the same time, the index was used to select the different key growth stages of winter wheat for yield estimation. The results showed that the relative error of total yield during the filling period was low, nearly 5%. The research results show that the combination of domestic meteorological satellite Fengyun-3 and ALMANAC crop model for crop growth monitoring and yield estimation is feasible, and further expands the application range of domestic satellites.
文摘《上海年鉴(1854)》是North China Herald(《北华捷报》)出版的第三本《上海年鉴》。虽然书名“Shanhae Almanac for 1854”,但详析Almanac一词源流,该词实际上包含了历书以外的内容,故应译作“上海年鉴”而非“上海历书”。Almanac既然兼有年鉴与历书两义,就必定与某一文化或某一地域相关连。通过搜集整理早期上海地区中西文报章杂志与书刊中发布出来的有关租界以及上海城市的信息,从这些海量信息中分析观察开埠以来上海城市的近代化进程,从1850年到20世纪上海城市面貌的变迁,这是一件极其有意义的事。但是近代文献散佚严重,这些珍贵的信息文献资料往往不可得。不久前上海图书馆购入的罗氏藏书中有1854年上海年鉴是十分珍贵的典籍。据高第同书目所载该年鉴有1852年到1863年(其中1859与1862两年未见)十种,是一个系列的书,但今天已不能得其全。连续出版的《上海年鉴》对于研究和观察开埠以后上海面貌的逐年变化情况,无疑是极其有用的史料。《上海年鉴》如此珍稀,值得我们认真研究。同时,《〈上海年鉴(1854)〉研究》就是对目前可见的最早的一本《上海年鉴》内容的全面介绍与分析,希望能有助于读者一窥上海开埠初期的上海城市面貌。
