Recently, Chen and his team were active in the theoretical and practical study of a new heliostat for the use of solar energy. This work represents the first innovation in the area of heliostats after many years of li...Recently, Chen and his team were active in the theoretical and practical study of a new heliostat for the use of solar energy. This work represents the first innovation in the area of heliostats after many years of little progress. The mathematical development of the tracking and concentration optics principles, and the practical implementation and demonstration of the technology, are both very interesting advances in this field. Many applications are possible for this technology such as generation of solar electricity and solar industrial process heat.展开更多
Photothermal conversion for water vapor gen- eration is a novel strategy and an efficient way to utilize solar energy, which has great potential for water purification and desalination. In this review, the development...Photothermal conversion for water vapor gen- eration is a novel strategy and an efficient way to utilize solar energy, which has great potential for water purification and desalination. In this review, the development of photothermal conversion and the classification of absorbers for solar vapor generation systems are presented, especially in recent devel- opment of carbon nanocomposites （carbon nanotubes and graphene） as solar vapor generation devices. Combined with recent progresses and achievements in this field, we discuss the challenges and opportunities for photothermal conversion based on carbon nanocomposites as well as their promising applications.展开更多
The accurate measurement of the dynamics of photosynthesis in China’s subtropical evergreen forest ecosystems is an important contribution to carbon(C) sink estimates in global terrestrial ecosystems and their respon...The accurate measurement of the dynamics of photosynthesis in China’s subtropical evergreen forest ecosystems is an important contribution to carbon(C) sink estimates in global terrestrial ecosystems and their responses to climate change. Eddy covariance has historically been the only direct method to assess C flux of whole ecosystems with high temporal resolution, but it suffers from limited spatial resolution. During the last decade, continuous global monitoring of plant primary productivity from spectroradiometer sensors on flux towers and satellites has extended the temporal and spatial coverage of C flux observations. In this study, we evaluated the performance of two physiological remote sensing indices, fluorescence reflectance index(FRI) and photochemical reflectance index(PRI), to measure the seasonal variations of photosynthesis in a subtropical evergreen forest ecosystem using continuous canopy spectral and flux measurements in the Dinghushan Nature Reserve in southern China.The more commonly used NDVI has been shown to be saturated and mainly affected by illumination(R^2=0.88, p <0.001), but FRI and PRI could better track the seasonal dynamics of plant photosynthetic functioning by comparison and are less affected by illumination(R^2=0.13 and R^2=0.51, respectively) at the seasonal scale. FRI correlated better with daily gross primary production(GPP) in the morning hours than in the afternoon hours, in contrast to PRI which correlated better with light-use efficiency(LUE) in the afternoon hours. Both FRI and PRI could show greater correlations with GPP and LUE respectively in the senescence season than in the recovery-growth season. When incident PAR was taken into account, the relationship between GPP and FRI was improved and the correlation coefficient increased from 0.22 to 0.69(p < 0.001). The strength of the correlation increased significantly in the senescence season(R^2=0.79, p < 0.001). Our results demonstrate the application of FRI and PRI as physiological indices for the accurate measurement of the seasonal dynamics of plant community photosynthesis in a subtropical evergreen forest, and suggest these indices may be applied to carbon cycle models to improve the estimation of regional carbon budgets.展开更多
文摘Recently, Chen and his team were active in the theoretical and practical study of a new heliostat for the use of solar energy. This work represents the first innovation in the area of heliostats after many years of little progress. The mathematical development of the tracking and concentration optics principles, and the practical implementation and demonstration of the technology, are both very interesting advances in this field. Many applications are possible for this technology such as generation of solar electricity and solar industrial process heat.
基金supported by the National Key R&D Program of China (2016YFA0200200)the Key Laboratory of Textile Fiber & Product (Wuhan Textile University)Ministry of Education (FZXW006)
文摘Photothermal conversion for water vapor gen- eration is a novel strategy and an efficient way to utilize solar energy, which has great potential for water purification and desalination. In this review, the development of photothermal conversion and the classification of absorbers for solar vapor generation systems are presented, especially in recent devel- opment of carbon nanocomposites （carbon nanotubes and graphene） as solar vapor generation devices. Combined with recent progresses and achievements in this field, we discuss the challenges and opportunities for photothermal conversion based on carbon nanocomposites as well as their promising applications.
基金National Key Research and Development Program of China(2017YFC0503803)National Natural Science Foundation of China(41571192)+1 种基金Natural Science Foundation of Hebei,China(D2016302002)Science and Technology Planning Project of Hebei,China(17390313D)
文摘The accurate measurement of the dynamics of photosynthesis in China’s subtropical evergreen forest ecosystems is an important contribution to carbon(C) sink estimates in global terrestrial ecosystems and their responses to climate change. Eddy covariance has historically been the only direct method to assess C flux of whole ecosystems with high temporal resolution, but it suffers from limited spatial resolution. During the last decade, continuous global monitoring of plant primary productivity from spectroradiometer sensors on flux towers and satellites has extended the temporal and spatial coverage of C flux observations. In this study, we evaluated the performance of two physiological remote sensing indices, fluorescence reflectance index(FRI) and photochemical reflectance index(PRI), to measure the seasonal variations of photosynthesis in a subtropical evergreen forest ecosystem using continuous canopy spectral and flux measurements in the Dinghushan Nature Reserve in southern China.The more commonly used NDVI has been shown to be saturated and mainly affected by illumination(R^2=0.88, p <0.001), but FRI and PRI could better track the seasonal dynamics of plant photosynthetic functioning by comparison and are less affected by illumination(R^2=0.13 and R^2=0.51, respectively) at the seasonal scale. FRI correlated better with daily gross primary production(GPP) in the morning hours than in the afternoon hours, in contrast to PRI which correlated better with light-use efficiency(LUE) in the afternoon hours. Both FRI and PRI could show greater correlations with GPP and LUE respectively in the senescence season than in the recovery-growth season. When incident PAR was taken into account, the relationship between GPP and FRI was improved and the correlation coefficient increased from 0.22 to 0.69(p < 0.001). The strength of the correlation increased significantly in the senescence season(R^2=0.79, p < 0.001). Our results demonstrate the application of FRI and PRI as physiological indices for the accurate measurement of the seasonal dynamics of plant community photosynthesis in a subtropical evergreen forest, and suggest these indices may be applied to carbon cycle models to improve the estimation of regional carbon budgets.
