Decreasing wind speed is one aspect of global climate change as well as global warming, and has become a new research orientation in recent decades. The decrease is especially evident in places with frequent perennial...Decreasing wind speed is one aspect of global climate change as well as global warming, and has become a new research orientation in recent decades. The decrease is especially evident in places with frequent perennially high wind speeds. We simulated decreased wind speed by using a steel-sheet wind shield in a temperate grassland in Inner Mongolia to examine the changes in physical environmental variables, as well as their impacts on the photosynthesis of grass leaves and net ecosystem exchange （NEE）. We then used models to calculate the variation of boundary layer conductance （BLC） and its impact on leaf photosynthesis, and this allowed us to separate the direct effects of wind speed reduction on leaf photo- synthesis （BLC） from the indirect ones （via soil moisture balance）. The results showed that reduced wind speed primarily resulted in higher moisture and temperature in soil, and indirectly affected net assimilation and water use efficiency of the prevalent bunch grass Stipa krylovii. Moreover, the wind-sheltered plant community had a stronger ability to sequester carbon than did the wind-exposed community during the growing season.展开更多
Computational fluid dynamics( CFD) techniques are used to investigate effects of both wind direction and wind speed on net solar heat gain of south wall with internal insulation in winter.Results show that wind effect...Computational fluid dynamics( CFD) techniques are used to investigate effects of both wind direction and wind speed on net solar heat gain of south wall with internal insulation in winter.Results show that wind effect has a significant influence on the net solar heat gain,where the impact of wind direction is stronger than that of wind speed. For regions in lower reaches of the Yangtze River,difference of their average net solar heat gains( NSHGS) is about 20% due to various wind speeds and wind directions.Buildings in districts with a dominant wind direction of north achieve the highest solar energy utilization.展开更多
为提高风洞调试和运行时的结构安全性,设计研制一种大型低速风洞结构健康监测系统。针对风洞监测对象位置散、可移动的特点,对结构健康监测(structural health monitoring,SHM)需求进行精准分析。在分析基础上,系统采用基于光纤环网和...为提高风洞调试和运行时的结构安全性,设计研制一种大型低速风洞结构健康监测系统。针对风洞监测对象位置散、可移动的特点,对结构健康监测(structural health monitoring,SHM)需求进行精准分析。在分析基础上,系统采用基于光纤环网和星形连接的混合网络架构,实现对分散结构状态数据的分布式采集、边缘计算和高效传输。运行系统表明:该系统在消声室流致振动监测评估、防护网拦截异物监测诊断等方面发挥了显著作用,有力保障了大型低速风洞运行安全。展开更多
基金supported by the National Science Foundation of China (Nos. 41171445 and 41321001)the State Key Laboratory of Earth Surface Processes and Resources Ecology (No. 2012-TDZY-31)the National Program on Key Basic Research Project (No. 2014CB954303)
文摘Decreasing wind speed is one aspect of global climate change as well as global warming, and has become a new research orientation in recent decades. The decrease is especially evident in places with frequent perennially high wind speeds. We simulated decreased wind speed by using a steel-sheet wind shield in a temperate grassland in Inner Mongolia to examine the changes in physical environmental variables, as well as their impacts on the photosynthesis of grass leaves and net ecosystem exchange （NEE）. We then used models to calculate the variation of boundary layer conductance （BLC） and its impact on leaf photosynthesis, and this allowed us to separate the direct effects of wind speed reduction on leaf photo- synthesis （BLC） from the indirect ones （via soil moisture balance）. The results showed that reduced wind speed primarily resulted in higher moisture and temperature in soil, and indirectly affected net assimilation and water use efficiency of the prevalent bunch grass Stipa krylovii. Moreover, the wind-sheltered plant community had a stronger ability to sequester carbon than did the wind-exposed community during the growing season.
基金National Natural Science Foundation of China(No.51478098)Innovation Foundation of Shanghai Education Commission,China(No.13ZZ054)
文摘Computational fluid dynamics( CFD) techniques are used to investigate effects of both wind direction and wind speed on net solar heat gain of south wall with internal insulation in winter.Results show that wind effect has a significant influence on the net solar heat gain,where the impact of wind direction is stronger than that of wind speed. For regions in lower reaches of the Yangtze River,difference of their average net solar heat gains( NSHGS) is about 20% due to various wind speeds and wind directions.Buildings in districts with a dominant wind direction of north achieve the highest solar energy utilization.
文摘为提高风洞调试和运行时的结构安全性,设计研制一种大型低速风洞结构健康监测系统。针对风洞监测对象位置散、可移动的特点,对结构健康监测(structural health monitoring,SHM)需求进行精准分析。在分析基础上,系统采用基于光纤环网和星形连接的混合网络架构,实现对分散结构状态数据的分布式采集、边缘计算和高效传输。运行系统表明:该系统在消声室流致振动监测评估、防护网拦截异物监测诊断等方面发挥了显著作用,有力保障了大型低速风洞运行安全。
