[目的]区域尺度的灌溉耕地空间分布信息是相关研究和管理的重要基础数据。中国的灌溉农业面积居全球第二位,但目前灌溉空间分布制图相对缺乏,且多依赖人工调查,利用遥感技术进行区域灌溉耕地制图成为未来发展趋势。针对目前对我国灌溉...[目的]区域尺度的灌溉耕地空间分布信息是相关研究和管理的重要基础数据。中国的灌溉农业面积居全球第二位,但目前灌溉空间分布制图相对缺乏,且多依赖人工调查,利用遥感技术进行区域灌溉耕地制图成为未来发展趋势。针对目前对我国灌溉耕地特征参量研究不足、难以描述灌溉耕地优势特征的空间差异性的缺陷,更好指导未来灌溉耕地制图。[方法]文章以高精度遥感产品作为真值,在对已有研究选用的分类参量进行统计分析的基础上,选取年降水、高程、坡度、地表水分指数和归一化植被指数作为不同类型特征参量的代表,通过单变量特征选择算法Select K Best,对我国北方不同地区的灌溉/雨养耕地的优势参量进行了系统分析,并针对主要问题提出了解决思路。[结果]研究结果显示,不同地区的优势特征类别呈现较大的地域差异,一些新特征被发现较常用的参量更有效;不同地区所呈现的特征优势原因各异。耕地基础禀赋、地理条件和灌溉结果三者互相关联,共同影响灌溉耕地空间信息提取的精度。[结论]耕地基础禀赋和灌溉结果最终归因于地理条件,地理条件是未来灌溉耕地制图中需要优先重点考虑的特征参量。展开更多
Generally, nanoparticles are easy to aggregate due to their nano sizes, which influence the physical and chemical properties. In this work, a dispersion treatment of the TiO2 nanoparticles with different average sizes...Generally, nanoparticles are easy to aggregate due to their nano sizes, which influence the physical and chemical properties. In this work, a dispersion treatment of the TiO2 nanoparticles with different average sizes was employed to improve the dispersion of TiO2 nanoparticles, in order to prepare flexible photoanodes for dye-sensitized solar cells (DSCs) with novel photovoltaic properties at a low temperature. The effects of dispersion treatment on the dispersion of TiO2 nanoparticles, including the viscosities of the binder-free TiO2 paste, the morphologies and textural properties of nanoparticle-TiO2 films, and the photovoltaic properties of the flexible DSCs, were investigated. Flexible indium-tin oxide (ITO)-coated polyethylene naphthalate (PEN) substrates with sputter deposited Pt were employed as the transparent flexible counter electrodes. A short-circuit photocurrent density of 9.62 mA·cm 2, an open-circuit voltage of 0.757 V, a fill factor of 0.589 and an overall light-to-energy conversion efficiency of 4.29% for the flexible DSCs under AM1.5 illumination of 100 mW cm 2 were obtained with dispersion treatment. A 30.8% increment of the energy conversion efficiency for DSCs made by dispersion treatment was obtained compared with that made without dispersion treatment.展开更多
文摘[目的]区域尺度的灌溉耕地空间分布信息是相关研究和管理的重要基础数据。中国的灌溉农业面积居全球第二位,但目前灌溉空间分布制图相对缺乏,且多依赖人工调查,利用遥感技术进行区域灌溉耕地制图成为未来发展趋势。针对目前对我国灌溉耕地特征参量研究不足、难以描述灌溉耕地优势特征的空间差异性的缺陷,更好指导未来灌溉耕地制图。[方法]文章以高精度遥感产品作为真值,在对已有研究选用的分类参量进行统计分析的基础上,选取年降水、高程、坡度、地表水分指数和归一化植被指数作为不同类型特征参量的代表,通过单变量特征选择算法Select K Best,对我国北方不同地区的灌溉/雨养耕地的优势参量进行了系统分析,并针对主要问题提出了解决思路。[结果]研究结果显示,不同地区的优势特征类别呈现较大的地域差异,一些新特征被发现较常用的参量更有效;不同地区所呈现的特征优势原因各异。耕地基础禀赋、地理条件和灌溉结果三者互相关联,共同影响灌溉耕地空间信息提取的精度。[结论]耕地基础禀赋和灌溉结果最终归因于地理条件,地理条件是未来灌溉耕地制图中需要优先重点考虑的特征参量。
基金supported by the National High Technology Research and Development Program of China (Grant No. 2011AA-050522)Sanjiang-yuan Scientific Program of Qinghai Science & Technology Department(Grant No. 2010-N-S03)the Ministry of Science & Technology (MOST) International S&T Cooperation Program of China (Grant No. 2010DFA-64360)
文摘Generally, nanoparticles are easy to aggregate due to their nano sizes, which influence the physical and chemical properties. In this work, a dispersion treatment of the TiO2 nanoparticles with different average sizes was employed to improve the dispersion of TiO2 nanoparticles, in order to prepare flexible photoanodes for dye-sensitized solar cells (DSCs) with novel photovoltaic properties at a low temperature. The effects of dispersion treatment on the dispersion of TiO2 nanoparticles, including the viscosities of the binder-free TiO2 paste, the morphologies and textural properties of nanoparticle-TiO2 films, and the photovoltaic properties of the flexible DSCs, were investigated. Flexible indium-tin oxide (ITO)-coated polyethylene naphthalate (PEN) substrates with sputter deposited Pt were employed as the transparent flexible counter electrodes. A short-circuit photocurrent density of 9.62 mA·cm 2, an open-circuit voltage of 0.757 V, a fill factor of 0.589 and an overall light-to-energy conversion efficiency of 4.29% for the flexible DSCs under AM1.5 illumination of 100 mW cm 2 were obtained with dispersion treatment. A 30.8% increment of the energy conversion efficiency for DSCs made by dispersion treatment was obtained compared with that made without dispersion treatment.