Hyperspectral reflectance (350-2500 nm) measurements were made over two experimental rice fields containing two cultivars treated with three levels of nitrogen application.Four different transformations of the reflect...Hyperspectral reflectance (350-2500 nm) measurements were made over two experimental rice fields containing two cultivars treated with three levels of nitrogen application.Four different transformations of the reflectance data were analyzed for their capability to predict rice biophysical parameters,comprising leaf area index (LAI;m-2 green leaf area m-2 soil) and green leaf chlorophyll density (GLCD;mg chlorophyll m 2 soil),using stepwise multiple regression (SMR) models and support vector machines (SVMs).Four transformations of the rice canopy data were made,comprising reflectances (R),first-order derivative reflectances (D1),second-order derivative reflectances (D2),and logarithm transformation of reflectances (LOG).The polynomial kernel (POLY) of the SVM using R was the best model to predict rice LAI,with a root mean square error (RMSE) of 1.0496 LAI units.The analysis of variance kernel of SVM using LOG was the best model to predict rice GLCD,with an RMSE of 523.0741 mg m-2.The SVM approach was not only superior to SMR models for predicting the rice biophysical parameters,but also provided a useful exploratory and predictive tool for analyzing different transformations of reflectance data.展开更多
A regional groundwater management system has been elaborated, integrating Relational Database Management System （RDBMS） and various web services. It consists of web geospatial application so-called HydrlS （ Hydroge...A regional groundwater management system has been elaborated, integrating Relational Database Management System （RDBMS） and various web services. It consists of web geospatial application so-called HydrlS （ Hydrogeological Information System） based on Open Source components and technologies, leading to a feasible and low-cost solution. Therefore, HydrlS permits delivery of data from a number of heterogeneous sources to standards supported by the Open Geospatial Consortium （OGC）. The protocols used for exchanging data are also derived from OGC standards, i.e., WMS （Web Mapping Service）, WFS （Web Feature Service）, and WCS （Web Coverage Service）. Finally, a geoportal was developed, which consists of client-applications that communicate with different Web Services （WMS, WCS, and WFS） through HTTP-requests. A prototype for web-based GIS application was designed using the deegree Framework to provide systematic interfaces and functions. This system was developed to demonstrate the value of making hydrogeological data more widely accessible through client/server architecture. This experience and knowledge already gained in this project will be a source for technology transfer and policy decisions. Otherwise, this will enable user groups to improve the management of their groundwater resources and contribute to enhanced decision support capabilities.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos. 40571115 and 40271078)the National Hi-Tech Research and Development Program of China(Grant No. 2006AA10Z203)
文摘Hyperspectral reflectance (350-2500 nm) measurements were made over two experimental rice fields containing two cultivars treated with three levels of nitrogen application.Four different transformations of the reflectance data were analyzed for their capability to predict rice biophysical parameters,comprising leaf area index (LAI;m-2 green leaf area m-2 soil) and green leaf chlorophyll density (GLCD;mg chlorophyll m 2 soil),using stepwise multiple regression (SMR) models and support vector machines (SVMs).Four transformations of the rice canopy data were made,comprising reflectances (R),first-order derivative reflectances (D1),second-order derivative reflectances (D2),and logarithm transformation of reflectances (LOG).The polynomial kernel (POLY) of the SVM using R was the best model to predict rice LAI,with a root mean square error (RMSE) of 1.0496 LAI units.The analysis of variance kernel of SVM using LOG was the best model to predict rice GLCD,with an RMSE of 523.0741 mg m-2.The SVM approach was not only superior to SMR models for predicting the rice biophysical parameters,but also provided a useful exploratory and predictive tool for analyzing different transformations of reflectance data.
文摘A regional groundwater management system has been elaborated, integrating Relational Database Management System （RDBMS） and various web services. It consists of web geospatial application so-called HydrlS （ Hydrogeological Information System） based on Open Source components and technologies, leading to a feasible and low-cost solution. Therefore, HydrlS permits delivery of data from a number of heterogeneous sources to standards supported by the Open Geospatial Consortium （OGC）. The protocols used for exchanging data are also derived from OGC standards, i.e., WMS （Web Mapping Service）, WFS （Web Feature Service）, and WCS （Web Coverage Service）. Finally, a geoportal was developed, which consists of client-applications that communicate with different Web Services （WMS, WCS, and WFS） through HTTP-requests. A prototype for web-based GIS application was designed using the deegree Framework to provide systematic interfaces and functions. This system was developed to demonstrate the value of making hydrogeological data more widely accessible through client/server architecture. This experience and knowledge already gained in this project will be a source for technology transfer and policy decisions. Otherwise, this will enable user groups to improve the management of their groundwater resources and contribute to enhanced decision support capabilities.
