高温氧指数测定仪(high temperature oxygen index tester)是一种用于评估被测材料在高温热辐射条件下燃烧性能的测定仪器。它的工作原理是计算被测材料在高温环境中维持基本的燃烧所需的极限氧浓度来确定被测材料的氧指数。高温氧指数...高温氧指数测定仪(high temperature oxygen index tester)是一种用于评估被测材料在高温热辐射条件下燃烧性能的测定仪器。它的工作原理是计算被测材料在高温环境中维持基本的燃烧所需的极限氧浓度来确定被测材料的氧指数。高温氧指数测定仪是对传统氧指数测定设备的升级和补充,可以极大的丰富被测材料的应用领域和使用范围,在阻燃材料、消防工程领域和五金制品材料具有较高的使用意义。展开更多
Accurate quantification of aboveground biomass of grasslands in alpine regions plays an important role in accurate quantification of global carbon cycling.The monthly normalized difference vegetation index（NDVI）,enh...Accurate quantification of aboveground biomass of grasslands in alpine regions plays an important role in accurate quantification of global carbon cycling.The monthly normalized difference vegetation index（NDVI）,enhanced vegetation index（EVI）,mean air temperature（Ta）,≥5℃ accumulated air temperature（AccT）,total precipitation（TP）,and the ratio of TP to AccT（TP/AccT） were used to model aboveground biomass（AGB） in grasslands on the Tibetan Plateau.Three stepwise multiple regression methods,including stepwise multiple regression of AGB with NDVI and EVI,stepwise multiple regression of AGB with Ta,AccT,TP and TP/AccT,and stepwise multiple regression of AGB with NDVI,EVI,Ta,AccT,TP and TP/Acc T were compared.The mean absolute error（MAE） and root mean squared error（RMSE） values between estimated AGB by the NDVI and measured AGB were 31.05 g m^（-2） and 44.12 g m^（-2）,and 95.43 g m^（-2） and 131.58 g m^（-2） in the meadow and steppe,respectively.The MAE and RMSE values between estimated AGB by the AccT and measured AGB were 33.61 g m^（-2） and 48.04 g m^（-2） in the steppe,respectively.The MAE and RMSE values between estimated AGB by the vegetation index and climatic data and measured AGB were 28.09 g m^（-2） and 42.71 g m^（-2）,and 35.86 g m^（-2） and 47.94 g m^（-2）,in the meadow and steppe,respectively.The study finds that a combination of vegetation index and climatic data can improve the accuracy of estimates of AGB that are arrived at using the vegetation index or climatic data.The accuracy of estimates varied depending on the type of grassland.展开更多
文摘高温氧指数测定仪(high temperature oxygen index tester)是一种用于评估被测材料在高温热辐射条件下燃烧性能的测定仪器。它的工作原理是计算被测材料在高温环境中维持基本的燃烧所需的极限氧浓度来确定被测材料的氧指数。高温氧指数测定仪是对传统氧指数测定设备的升级和补充,可以极大的丰富被测材料的应用领域和使用范围,在阻燃材料、消防工程领域和五金制品材料具有较高的使用意义。
基金National Natural Science Foundation of China(31600432)National Key Research Projects of China(2016YFC0502005+3 种基金2016YFC0502006)Chinese Academy of Science Western Light Talents Program(Response of livestock carrying capability to climatic change and grazing in the alpine meadow of Northern Tibetan Plateau)Science and Technology Plan Projects of Tibet Autonomous Region(Forage Grass Industry)National Science and Technology Plan Project of China(2013BAC04B01,2011BAC09B03,2007BAC06B01)
文摘Accurate quantification of aboveground biomass of grasslands in alpine regions plays an important role in accurate quantification of global carbon cycling.The monthly normalized difference vegetation index（NDVI）,enhanced vegetation index（EVI）,mean air temperature（Ta）,≥5℃ accumulated air temperature（AccT）,total precipitation（TP）,and the ratio of TP to AccT（TP/AccT） were used to model aboveground biomass（AGB） in grasslands on the Tibetan Plateau.Three stepwise multiple regression methods,including stepwise multiple regression of AGB with NDVI and EVI,stepwise multiple regression of AGB with Ta,AccT,TP and TP/AccT,and stepwise multiple regression of AGB with NDVI,EVI,Ta,AccT,TP and TP/Acc T were compared.The mean absolute error（MAE） and root mean squared error（RMSE） values between estimated AGB by the NDVI and measured AGB were 31.05 g m^（-2） and 44.12 g m^（-2）,and 95.43 g m^（-2） and 131.58 g m^（-2） in the meadow and steppe,respectively.The MAE and RMSE values between estimated AGB by the AccT and measured AGB were 33.61 g m^（-2） and 48.04 g m^（-2） in the steppe,respectively.The MAE and RMSE values between estimated AGB by the vegetation index and climatic data and measured AGB were 28.09 g m^（-2） and 42.71 g m^（-2）,and 35.86 g m^（-2） and 47.94 g m^（-2）,in the meadow and steppe,respectively.The study finds that a combination of vegetation index and climatic data can improve the accuracy of estimates of AGB that are arrived at using the vegetation index or climatic data.The accuracy of estimates varied depending on the type of grassland.
