Terrestrial ecosystem and climate system are closely related to each other. Faced with the unavoidable global climate change, it is important to investigate terrestrial ecosystem responding to climate change. In inlan...Terrestrial ecosystem and climate system are closely related to each other. Faced with the unavoidable global climate change, it is important to investigate terrestrial ecosystem responding to climate change. In inland river basin of arid and semi-arid regions in China, sensitivity difference of vegetation responding to climate change from 1998 to 2007 was analyzed in this paper. （1） Differences in the global spatio-temporal distribution of vegetation and climate are obvious. The vegetation change shows a slight degradation in this whole region. Degradation is more obvious in densely vegetated areas. Temperature shows a general downward trend with a linear trend coefficient of -1.1467. Conversely, precipitation shows an increasing trend with a linear trend coefficient of 0.3896. （2） About the central tendency response, there are similar features in spatial distribution of both NDVI responding to precipitation （NDVI-P） and NDVI responding to AI （NDVI-AI）, which are contrary to that of NDVI responding to air temperature （NDVI-T）. Typical sensitivity region of NDVI-P and NDVI-AI mainly covers the northern temperate arid steppe and the northern temperate desert steppe. NDVI-T typical sensitivity region mainly covers the northern temperate desert steppe. （3） Regarding the fluctuation amplitude response, NDVI-T is dominated by the lower sensitivity, typical regions of the warm temperate shrubby, selui-shrubby, bare extreme dry desert, and northern temperate meadow steppe in the east and temperate semi-shrubby, dwarf arboreous desert in the north are high response. （4） Fluctuation amplitude responses between NDVI-P and NDVI-AI present a similar spatial distribution. The typical sensitivity region mainly covers the northern temperate desert steppe. There are various linear change trend responses of NDVI-T, NDVI-P and NDVI-AI. As to the NDVI-T and NDVI-AI, which are influenced by the boundary effect of semi-arid and semi-humid climate zones, there is less correlation of their linear change tend展开更多
碳达峰、碳中和目标将加速我国能源系统的低碳转型。为促进全社会的协同行动,需要一个未来低碳能源系统的清晰、完整图景来提供前瞻性引导。而目前,未来低碳能源系统的形态、特征以及敏感性因素尚研究不足。该文发展了一套能源-物质流...碳达峰、碳中和目标将加速我国能源系统的低碳转型。为促进全社会的协同行动,需要一个未来低碳能源系统的清晰、完整图景来提供前瞻性引导。而目前,未来低碳能源系统的形态、特征以及敏感性因素尚研究不足。该文发展了一套能源-物质流耦合及敏感性分析方法,建立了2050年低碳能源系统的计量基础,描绘了其整体能源流向和二氧化碳排放源、汇的关系,并分析了其主要组成部分的结构和效率一旦发生变化对二氧化碳排放总量的影响。结果表明,未来低碳能源系统可能将呈现非化石能源为主的一次能源结构和发电结构以及高比例终端电力占比等基本形态,并可能具有电力部门负排放、工业部门排放最大等基本碳排放特征。该系统的碳排放总量对工业部门的电力占比和化石能源发电的效率变化最为敏感,其次是风电占比提高、更多煤电安装碳捕获和封存(carbon capture and sequestration, CCS)及化石能源发电的余热利用等。为此,该文建议严格控制化石能源的终端直接利用,加速电力部门低碳进程,加强探索难减排部门的低碳路径和非化石非电利用,以及大力建设智慧能源系统来保障多能互补。展开更多
In this study, finite element （FE）-based primary pavement response models are employed for investigating the early-age deformation characteristics of jointed plain concrete pavements （JPCP） under environmental eff...In this study, finite element （FE）-based primary pavement response models are employed for investigating the early-age deformation characteristics of jointed plain concrete pavements （JPCP） under environmental effects. The FE-based ISLAB （two-and-one-half-dimensional） and EverFE （three-dimensional） software were used to conduct the response analysis. Sensitivity analyses of input parameters used in ISLAB and EverFE were conducted based on field and laboratory test data collected from instrumented pavements on highway US-34 near Burlington, Iowa. Based on the combination of input parameters and equivalent temperatures established from preliminary studies, FE analyses were performed and compared with the field measurements. Comparisons between field measured and computed deformations showed that both FE programs could produce reasonably accurate estimates of actual slab deformations due to environmental effects using the equivalent temperature difference concept.展开更多
基金Beijing Science and Technology New Star Program, No.2010B037Environmental Commonweal Projects,No.2011467026National Science and Technology Supporting Item, No.2008BAC34B06
文摘Terrestrial ecosystem and climate system are closely related to each other. Faced with the unavoidable global climate change, it is important to investigate terrestrial ecosystem responding to climate change. In inland river basin of arid and semi-arid regions in China, sensitivity difference of vegetation responding to climate change from 1998 to 2007 was analyzed in this paper. （1） Differences in the global spatio-temporal distribution of vegetation and climate are obvious. The vegetation change shows a slight degradation in this whole region. Degradation is more obvious in densely vegetated areas. Temperature shows a general downward trend with a linear trend coefficient of -1.1467. Conversely, precipitation shows an increasing trend with a linear trend coefficient of 0.3896. （2） About the central tendency response, there are similar features in spatial distribution of both NDVI responding to precipitation （NDVI-P） and NDVI responding to AI （NDVI-AI）, which are contrary to that of NDVI responding to air temperature （NDVI-T）. Typical sensitivity region of NDVI-P and NDVI-AI mainly covers the northern temperate arid steppe and the northern temperate desert steppe. NDVI-T typical sensitivity region mainly covers the northern temperate desert steppe. （3） Regarding the fluctuation amplitude response, NDVI-T is dominated by the lower sensitivity, typical regions of the warm temperate shrubby, selui-shrubby, bare extreme dry desert, and northern temperate meadow steppe in the east and temperate semi-shrubby, dwarf arboreous desert in the north are high response. （4） Fluctuation amplitude responses between NDVI-P and NDVI-AI present a similar spatial distribution. The typical sensitivity region mainly covers the northern temperate desert steppe. There are various linear change trend responses of NDVI-T, NDVI-P and NDVI-AI. As to the NDVI-T and NDVI-AI, which are influenced by the boundary effect of semi-arid and semi-humid climate zones, there is less correlation of their linear change tend
文摘碳达峰、碳中和目标将加速我国能源系统的低碳转型。为促进全社会的协同行动,需要一个未来低碳能源系统的清晰、完整图景来提供前瞻性引导。而目前,未来低碳能源系统的形态、特征以及敏感性因素尚研究不足。该文发展了一套能源-物质流耦合及敏感性分析方法,建立了2050年低碳能源系统的计量基础,描绘了其整体能源流向和二氧化碳排放源、汇的关系,并分析了其主要组成部分的结构和效率一旦发生变化对二氧化碳排放总量的影响。结果表明,未来低碳能源系统可能将呈现非化石能源为主的一次能源结构和发电结构以及高比例终端电力占比等基本形态,并可能具有电力部门负排放、工业部门排放最大等基本碳排放特征。该系统的碳排放总量对工业部门的电力占比和化石能源发电的效率变化最为敏感,其次是风电占比提高、更多煤电安装碳捕获和封存(carbon capture and sequestration, CCS)及化石能源发电的余热利用等。为此,该文建议严格控制化石能源的终端直接利用,加速电力部门低碳进程,加强探索难减排部门的低碳路径和非化石非电利用,以及大力建设智慧能源系统来保障多能互补。
文摘In this study, finite element （FE）-based primary pavement response models are employed for investigating the early-age deformation characteristics of jointed plain concrete pavements （JPCP） under environmental effects. The FE-based ISLAB （two-and-one-half-dimensional） and EverFE （three-dimensional） software were used to conduct the response analysis. Sensitivity analyses of input parameters used in ISLAB and EverFE were conducted based on field and laboratory test data collected from instrumented pavements on highway US-34 near Burlington, Iowa. Based on the combination of input parameters and equivalent temperatures established from preliminary studies, FE analyses were performed and compared with the field measurements. Comparisons between field measured and computed deformations showed that both FE programs could produce reasonably accurate estimates of actual slab deformations due to environmental effects using the equivalent temperature difference concept.
