土壤盐渍化是干旱半干旱区土壤资源损害、生境破坏和农业生产损失的重要影响因素,定量反演和监测盐渍化土壤,对防护土地生态安全具有重要意义.文章基于光谱变换筛选盐分特征波段和特征光谱指数,构建实测高光谱和Sentinel-2B影像的岭回...土壤盐渍化是干旱半干旱区土壤资源损害、生境破坏和农业生产损失的重要影响因素,定量反演和监测盐渍化土壤,对防护土地生态安全具有重要意义.文章基于光谱变换筛选盐分特征波段和特征光谱指数,构建实测高光谱和Sentinel-2B影像的岭回归模型和偏最小二乘回归盐分反演模型,并以特征光谱指数为敏感参量进行星‒地光谱匹配,构建匹配后盐分反演模型,实现银川平原土壤盐分定量反演.结果表明,盐分指数3(Salinity index 3,S3)、强度指数1(Intensity index 1,Int1)和强度指数2(Intensity index 2,Int2)能够实现实测高光谱端元到多光谱像元尺度的匹配,有效地提升模型精度;经光谱匹配后构建的偏最小二乘模型精度最高(R2=0.721,RMSE=4.856 g·kg^(−1)).相比单独利用影像建模,其R2提升了0.309,均方根误差(Root Mean Square Error,RMSE)减小了2.085 g·kg^(−1).盐分反演结果与实地采样具有较好一致性,表明特征光谱指数可为不同尺度遥感数据间光谱匹配与联合,实现地表点到空间面尺度盐渍化定量监测,为土壤盐分监测提供理论借鉴和实践参考.展开更多
为探究沿黄经济区工农业经济迅速发展所引起的土地利用频繁变化,基于地理信息系统(geographical information system,GIS)空间分析技术,通过转移矩阵、地学信息图谱、标准差椭圆、核密度和热点分析法,探究该区各地类数量结构演化和空间...为探究沿黄经济区工农业经济迅速发展所引起的土地利用频繁变化,基于地理信息系统(geographical information system,GIS)空间分析技术,通过转移矩阵、地学信息图谱、标准差椭圆、核密度和热点分析法,探究该区各地类数量结构演化和空间格局特征。结果表明:近38 a,建设用地和耕地大幅增长,其他地类均有减少,耕地流转为建设用地,主要来源为开垦草地和未利用地,水域林地略微减少,变化率低于1%;空间分异上,图谱单元以水域向草地和耕地转化为主导,集中分布于平罗县、贺兰山脚和黄河以东,其次为耕地转为建设用地,主要发生在青铜峡市和利通区;地类变化在空间上呈现东北-西南的集中分布趋势,覆盖范围逐渐趋于扩张;沿黄城市群以耕地、居民点和建设用地为主,工农业快速发展加速了地类的转化,成为土地利用的热点和密集区。贺兰山自然保护区和白芨滩生态保护区,地类以林地和荒漠草原为主,是土地利用的冷点区。展开更多
Teaching evaluation on a WebGIS course is a multi-objective nonlinear high-dimensional NP-hard problem. The index system for the teaching evaluation of a WebGIS course, including teacher- and student-oriented sub-syst...Teaching evaluation on a WebGIS course is a multi-objective nonlinear high-dimensional NP-hard problem. The index system for the teaching evaluation of a WebGIS course, including teacher- and student-oriented sub-systems, is first established and used for questionnaires from 2013 to 2017. The multi-objective nonlinear high-dimensional evaluation model is constructed and then solved via dynamic self-adaptive teaching–learning-based optimization (DSATLBO). DSATLBO is based on teaching–learning-based optimization with five improvements: dynamic nonlinear self-adaptive teaching factor, extracurricular tutorship factor, dynamic self-adaptive learning factor, multi-way learning factor, and non-dominated sorting factor. WebGIS teaching performance is fully evaluated based on questionnaires and DSATLBO. Optimal weights and weighted scores from DSATLBO are compared with those from the non-dominated sorting genetic algorithm-II using the Pareto front, coverage to two sets, and spacing of the non-dominated solution sets to validate the performance of DSATLBO. The results show that DSATLBO can be uniformly distributed along the Pareto front. Therefore, DSATLBO can efficiently and feasibly solve the multi-objective nonlinear high-dimensional teaching evaluation model of a WebGIS course. The proposed teaching evaluation method can help reflecting the quality of all aspects of classroom teaching and guide the professional development of students.展开更多
文摘土壤盐渍化是干旱半干旱区土壤资源损害、生境破坏和农业生产损失的重要影响因素,定量反演和监测盐渍化土壤,对防护土地生态安全具有重要意义.文章基于光谱变换筛选盐分特征波段和特征光谱指数,构建实测高光谱和Sentinel-2B影像的岭回归模型和偏最小二乘回归盐分反演模型,并以特征光谱指数为敏感参量进行星‒地光谱匹配,构建匹配后盐分反演模型,实现银川平原土壤盐分定量反演.结果表明,盐分指数3(Salinity index 3,S3)、强度指数1(Intensity index 1,Int1)和强度指数2(Intensity index 2,Int2)能够实现实测高光谱端元到多光谱像元尺度的匹配,有效地提升模型精度;经光谱匹配后构建的偏最小二乘模型精度最高(R2=0.721,RMSE=4.856 g·kg^(−1)).相比单独利用影像建模,其R2提升了0.309,均方根误差(Root Mean Square Error,RMSE)减小了2.085 g·kg^(−1).盐分反演结果与实地采样具有较好一致性,表明特征光谱指数可为不同尺度遥感数据间光谱匹配与联合,实现地表点到空间面尺度盐渍化定量监测,为土壤盐分监测提供理论借鉴和实践参考.
文摘为探究沿黄经济区工农业经济迅速发展所引起的土地利用频繁变化,基于地理信息系统(geographical information system,GIS)空间分析技术,通过转移矩阵、地学信息图谱、标准差椭圆、核密度和热点分析法,探究该区各地类数量结构演化和空间格局特征。结果表明:近38 a,建设用地和耕地大幅增长,其他地类均有减少,耕地流转为建设用地,主要来源为开垦草地和未利用地,水域林地略微减少,变化率低于1%;空间分异上,图谱单元以水域向草地和耕地转化为主导,集中分布于平罗县、贺兰山脚和黄河以东,其次为耕地转为建设用地,主要发生在青铜峡市和利通区;地类变化在空间上呈现东北-西南的集中分布趋势,覆盖范围逐渐趋于扩张;沿黄城市群以耕地、居民点和建设用地为主,工农业快速发展加速了地类的转化,成为土地利用的热点和密集区。贺兰山自然保护区和白芨滩生态保护区,地类以林地和荒漠草原为主,是土地利用的冷点区。
基金Project(41661026)supported by the National Natural Science Foundation of ChinaProject supported by the Fund for the Construction of Western-China First-class Specialty of Ningxia University,China
文摘Teaching evaluation on a WebGIS course is a multi-objective nonlinear high-dimensional NP-hard problem. The index system for the teaching evaluation of a WebGIS course, including teacher- and student-oriented sub-systems, is first established and used for questionnaires from 2013 to 2017. The multi-objective nonlinear high-dimensional evaluation model is constructed and then solved via dynamic self-adaptive teaching–learning-based optimization (DSATLBO). DSATLBO is based on teaching–learning-based optimization with five improvements: dynamic nonlinear self-adaptive teaching factor, extracurricular tutorship factor, dynamic self-adaptive learning factor, multi-way learning factor, and non-dominated sorting factor. WebGIS teaching performance is fully evaluated based on questionnaires and DSATLBO. Optimal weights and weighted scores from DSATLBO are compared with those from the non-dominated sorting genetic algorithm-II using the Pareto front, coverage to two sets, and spacing of the non-dominated solution sets to validate the performance of DSATLBO. The results show that DSATLBO can be uniformly distributed along the Pareto front. Therefore, DSATLBO can efficiently and feasibly solve the multi-objective nonlinear high-dimensional teaching evaluation model of a WebGIS course. The proposed teaching evaluation method can help reflecting the quality of all aspects of classroom teaching and guide the professional development of students.