This paper identifies the shortcomings of variance and semi-variance methods in investment risk measurement and introduces a new model,namely RR-ER (relative risk and excess revenue) model,which takes account of the r...This paper identifies the shortcomings of variance and semi-variance methods in investment risk measurement and introduces a new model,namely RR-ER (relative risk and excess revenue) model,which takes account of the revenue over expectation problem.Properties of RR-ER model and the consistency between RR-ER model and traditional risk measure model with regard to continuous random variables are discussed.Case analysis is presented to prove the practicality and efficiency of this new method.展开更多
Ecological geographic regions, also called eco-regions, can be used to divide a remotely sensed image, which is helpful for reducing the complexity of land cover types within eco-regions and for improving the classifi...Ecological geographic regions, also called eco-regions, can be used to divide a remotely sensed image, which is helpful for reducing the complexity of land cover types within eco-regions and for improving the classification accuracy of land cover. In this case study in China, we improved a method of ecological geographic regionalization that is more suitable for remote sensing mapping of regional land cover, and we obtained new eco-regions. The canonical correspondence analysis(CCA) and k-means clustering were adopted in the ecological geographic regionalization using both seasonal remotely-sensed vegetation information and environmental data including climate, elevation and soil features. Our results show that the combination of seasonal vegetation information and the CCA performed well in the selection of the dominant environmental factor of the biogeographic pattern, and it can be used as regionalization indicators of eco-regions. We found that thermal factors are the most important driving forces of the biogeographic pattern in China, which followed by moisture factors. Two global land cover products(MODIS MCD12C1 and Glob Cover) were used to assess our eco-regions. The results show that our eco-regions performed better than that of a previous study regarding the complexity of land cover types, such as in the number of types and the proportional area of the major/secondary type. These results indicate that the method of ecological geographic regionalization, which is based on environmental factors associated with seasonal vegetation features, is effective for reducing the regional complexity of land cover.展开更多
文摘This paper identifies the shortcomings of variance and semi-variance methods in investment risk measurement and introduces a new model,namely RR-ER (relative risk and excess revenue) model,which takes account of the revenue over expectation problem.Properties of RR-ER model and the consistency between RR-ER model and traditional risk measure model with regard to continuous random variables are discussed.Case analysis is presented to prove the practicality and efficiency of this new method.
基金Financial support for the study was provided by the China Postdoctoral Science Foundation (Grant No. 2015M570431)the Jiangsu Provincial Natural Science Foundation of China (Grant No. BK20150579)the State High Technology Funds of China (Grant No. 2009AA122001)
文摘Ecological geographic regions, also called eco-regions, can be used to divide a remotely sensed image, which is helpful for reducing the complexity of land cover types within eco-regions and for improving the classification accuracy of land cover. In this case study in China, we improved a method of ecological geographic regionalization that is more suitable for remote sensing mapping of regional land cover, and we obtained new eco-regions. The canonical correspondence analysis(CCA) and k-means clustering were adopted in the ecological geographic regionalization using both seasonal remotely-sensed vegetation information and environmental data including climate, elevation and soil features. Our results show that the combination of seasonal vegetation information and the CCA performed well in the selection of the dominant environmental factor of the biogeographic pattern, and it can be used as regionalization indicators of eco-regions. We found that thermal factors are the most important driving forces of the biogeographic pattern in China, which followed by moisture factors. Two global land cover products(MODIS MCD12C1 and Glob Cover) were used to assess our eco-regions. The results show that our eco-regions performed better than that of a previous study regarding the complexity of land cover types, such as in the number of types and the proportional area of the major/secondary type. These results indicate that the method of ecological geographic regionalization, which is based on environmental factors associated with seasonal vegetation features, is effective for reducing the regional complexity of land cover.
