一个好的时空数据库逻辑设计目标是消除数据冗余以及插入、删除和更新异常。因此,对时空函数依赖STFD(Spatio-Temporal Function Dependency),时空关键字,时空完全函数依赖进行了定义,在此基础上对时空数据库进行了规范化研究,提出了时...一个好的时空数据库逻辑设计目标是消除数据冗余以及插入、删除和更新异常。因此,对时空函数依赖STFD(Spatio-Temporal Function Dependency),时空关键字,时空完全函数依赖进行了定义,在此基础上对时空数据库进行了规范化研究,提出了时空一范式、时空二范式、时空三范式,并对它们的规范化程度的高低次序进行了证明。展开更多
This study investigates the impact of global warming on drought/flood patterns in China at the end of the 21st century based on the simulations of 22 global climate models and a regional climate model(RegCM3) under th...This study investigates the impact of global warming on drought/flood patterns in China at the end of the 21st century based on the simulations of 22 global climate models and a regional climate model(RegCM3) under the SRES(Special Report on Emissions Scenarios) A1B scenario.The standardized precipitation index(SPI),which has well performance in monitoring the drought/flood characteristics(in terms of their intensity,duration,and spatial extent) in China,is used in this study.The projected results of 22 coupled models and the RegCM3 simulation are consistent.These models project a decrease in the frequency of droughts in most parts of northern China and a slight increase in the frequency in some parts of southern China.Considering China as a whole,the spatial extents of droughts are projected to be significantly reduced.In contrast,future flood events over most parts of China are projected to occur more frequently with stronger intensity and longer duration than those prevalent currently.Additionally,the spatial extents of flood events are projected to significantly increase.展开更多
文摘一个好的时空数据库逻辑设计目标是消除数据冗余以及插入、删除和更新异常。因此,对时空函数依赖STFD(Spatio-Temporal Function Dependency),时空关键字,时空完全函数依赖进行了定义,在此基础上对时空数据库进行了规范化研究,提出了时空一范式、时空二范式、时空三范式,并对它们的规范化程度的高低次序进行了证明。
基金supported by the National Basic Research Program of China (Grant No. 2012CB955401)the National Natural Science Foundation of China (Grant No. 41275078)supported by the "Strategic Priority Research Program-Climate Change:Carbon Budget and Relevant Issues" of the Chinese Academy of Sciences (Grant No. XDA05090306)
文摘This study investigates the impact of global warming on drought/flood patterns in China at the end of the 21st century based on the simulations of 22 global climate models and a regional climate model(RegCM3) under the SRES(Special Report on Emissions Scenarios) A1B scenario.The standardized precipitation index(SPI),which has well performance in monitoring the drought/flood characteristics(in terms of their intensity,duration,and spatial extent) in China,is used in this study.The projected results of 22 coupled models and the RegCM3 simulation are consistent.These models project a decrease in the frequency of droughts in most parts of northern China and a slight increase in the frequency in some parts of southern China.Considering China as a whole,the spatial extents of droughts are projected to be significantly reduced.In contrast,future flood events over most parts of China are projected to occur more frequently with stronger intensity and longer duration than those prevalent currently.Additionally,the spatial extents of flood events are projected to significantly increase.
