Village landscapes, which integrate small-scMe agriculture with housing, forestry, and a host of other land use practices, cover more than 2 million square kilometers across China. Village lands tend to be managed at ...Village landscapes, which integrate small-scMe agriculture with housing, forestry, and a host of other land use practices, cover more than 2 million square kilometers across China. Village lands tend to be managed at very fine spatial scales （≤ 30 m）, with managers both adapting their practices to existing variation in soils and terrain （e.g., fertile plains vs. infertile slopes） and also altering soil fertility and even terrain by terracing, irrigation, fertilizing, and other land use practices. Relationships between fine-scale land management patterns and soil organic carbon （SOC） in the top 30 cm of village soils were studied by sampling soils within fine-scale landscape features using a regionally weighted landscape sampling design across five environmentally distinct sites in China. SOC stocks across China＇s village regions （5 Pg C in the top 30 cm of 2 ×10^6 km^2） represent roughly 4% of the total SOC stocks in global croplands. Although macroclimate varied from temperate to tropical in this study, SOC density did not vary significantly with climate, though it was negatively correlated with regional mean elevation. The highest SOC densities within landscapes were found in agricultural lands, especially paddy, the lowest SOC densities were found in nonproductive lands, and forest lands tended toward moderate SOC densities. Bue to the high SOC densities of agricultural lands and their predominance in village landscapes, most village SOC was found in agricultural land, except in the tropical hilly region, where forestry accounted for about 45% of the SOC stocks. A surprisingly large portion of village SOC was associated with built structures and with the disturbed lands surrounding these structures, ranging from 〉 18% in the North China Plain to about 9% in the tropical hilly region. These results confirmed that local land use practices, combined with local and regional variation in terrain, were associated with most of the SOC variation within and across China＇s village landscapes and may be an important cause of regional variation in SOC.展开更多
ABSTRACT The multipath has long been considered a major error source in GPS applications .The characteristics 0f the GPS signal multipath effects are analyzed. based on which an experiment that considers the characte...ABSTRACT The multipath has long been considered a major error source in GPS applications .The characteristics 0f the GPS signal multipath effects are analyzed. based on which an experiment that considers the characteristics of dynamic deformation monitoring has been carried out. The solution results of observation data in two successive days are processed by a method,which combines the wavelet filtering and the differential correction betweentwo successive days. The research demonstrates that the multipath errors have stronger repeatability on successive days;after significantly mitigating the influence of multipath effects,the accuracy of three-dimensional positioning for GPS dynamic deformation monitoring can attain the mm level,an obvious accuracy improving particularly invertical component.The characteristics of GPS signal multipath,th eexperimental scheme and the qualitative and quantitative analysis of results are detailed.展开更多
A hierarchical non-linear method for image registration was presented, which integrates image segmentation and registration under a variational framework. An improved deformable model is used to simultaneously segment...A hierarchical non-linear method for image registration was presented, which integrates image segmentation and registration under a variational framework. An improved deformable model is used to simultaneously segment and register feature from multiple images. The objects in the image pair are segmented by evolving a single contour and meanwhile the parameters of affine registration transformation are found out. After that, a contour-constrained elastic registration is applied to register the images correctly. The experimental results indicate that the proposed approach is effective to segment and register medical images.展开更多
Based on the covariant prolongation structure technique,we construct the integrable higher-order deformations of the(2+1)-dimensional Heisenberg ferromagnet model and obtain their su(2) × R(λ) prolongation struc...Based on the covariant prolongation structure technique,we construct the integrable higher-order deformations of the(2+1)-dimensional Heisenberg ferromagnet model and obtain their su(2) × R(λ) prolongation structures.By associating these deformed multidimensional Heisenberg ferromagnet models with the moving space curve in Euclidean space and using the Hasimoto function,we derive their geometrical equivalent counterparts,i.e.,higher-order(2+1)-dimensional nonlinear Schrdinger equations.展开更多
基金Project supported by the US National Science Foundation (No. DEB-0075617)
文摘Village landscapes, which integrate small-scMe agriculture with housing, forestry, and a host of other land use practices, cover more than 2 million square kilometers across China. Village lands tend to be managed at very fine spatial scales （≤ 30 m）, with managers both adapting their practices to existing variation in soils and terrain （e.g., fertile plains vs. infertile slopes） and also altering soil fertility and even terrain by terracing, irrigation, fertilizing, and other land use practices. Relationships between fine-scale land management patterns and soil organic carbon （SOC） in the top 30 cm of village soils were studied by sampling soils within fine-scale landscape features using a regionally weighted landscape sampling design across five environmentally distinct sites in China. SOC stocks across China＇s village regions （5 Pg C in the top 30 cm of 2 ×10^6 km^2） represent roughly 4% of the total SOC stocks in global croplands. Although macroclimate varied from temperate to tropical in this study, SOC density did not vary significantly with climate, though it was negatively correlated with regional mean elevation. The highest SOC densities within landscapes were found in agricultural lands, especially paddy, the lowest SOC densities were found in nonproductive lands, and forest lands tended toward moderate SOC densities. Bue to the high SOC densities of agricultural lands and their predominance in village landscapes, most village SOC was found in agricultural land, except in the tropical hilly region, where forestry accounted for about 45% of the SOC stocks. A surprisingly large portion of village SOC was associated with built structures and with the disturbed lands surrounding these structures, ranging from 〉 18% in the North China Plain to about 9% in the tropical hilly region. These results confirmed that local land use practices, combined with local and regional variation in terrain, were associated with most of the SOC variation within and across China＇s village landscapes and may be an important cause of regional variation in SOC.
文摘ABSTRACT The multipath has long been considered a major error source in GPS applications .The characteristics 0f the GPS signal multipath effects are analyzed. based on which an experiment that considers the characteristics of dynamic deformation monitoring has been carried out. The solution results of observation data in two successive days are processed by a method,which combines the wavelet filtering and the differential correction betweentwo successive days. The research demonstrates that the multipath errors have stronger repeatability on successive days;after significantly mitigating the influence of multipath effects,the accuracy of three-dimensional positioning for GPS dynamic deformation monitoring can attain the mm level,an obvious accuracy improving particularly invertical component.The characteristics of GPS signal multipath,th eexperimental scheme and the qualitative and quantitative analysis of results are detailed.
基金National Natural Science Foundation ofChina (No.60271033)
文摘A hierarchical non-linear method for image registration was presented, which integrates image segmentation and registration under a variational framework. An improved deformable model is used to simultaneously segment and register feature from multiple images. The objects in the image pair are segmented by evolving a single contour and meanwhile the parameters of affine registration transformation are found out. After that, a contour-constrained elastic registration is applied to register the images correctly. The experimental results indicate that the proposed approach is effective to segment and register medical images.
基金Supported by National Natural Science Foundation of China under Grant Nos. 10975102 and 11031005Beijing Municipal Commission of Education under Grant No. KZ201210028032
文摘Based on the covariant prolongation structure technique,we construct the integrable higher-order deformations of the(2+1)-dimensional Heisenberg ferromagnet model and obtain their su(2) × R(λ) prolongation structures.By associating these deformed multidimensional Heisenberg ferromagnet models with the moving space curve in Euclidean space and using the Hasimoto function,we derive their geometrical equivalent counterparts,i.e.,higher-order(2+1)-dimensional nonlinear Schrdinger equations.
