A robust phenomenon termed the Arctic Amplification(AA)refers to the stronger warming taking place over the Arctic compared to the global mean.The AA can be confirmed through observations and reproduced in climate mod...A robust phenomenon termed the Arctic Amplification(AA)refers to the stronger warming taking place over the Arctic compared to the global mean.The AA can be confirmed through observations and reproduced in climate model simulations and shows significant seasonality and inter-model spread.This study focuses on the influence of surface type on the seasonality of AA and its inter-model spread by dividing the Arctic region into four surface types:ice-covered,ice-retreat,ice-free,and land.The magnitude and inter-model spread of Arctic surface warming are calculated from the difference between the abrupt-4×CO_(2)and pre-industrial experiments of 17 CMIP6 models.The change of effective thermal inertia(ETI)in response to the quadrupling of CO_(2) forcing is the leading mechanism for the seasonal energy transfer mechanism,which acts to store heat temporarily in summer and then release it in winter.The ETI change is strongest over the ice-retreat region,which is also responsible for the strongest AA among the four surface types.The lack of ETI change explains the nearly uniform warming pattern across seasons over the ice-free(ocean)region.Compared to other regions,the ice-covered region shows the maximum inter-model spread in JFM,resulting from a stronger inter-model spread in the oceanic heat storage term.However,the weaker upward surface turbulent sensible and latent heat fluxes tend to suppress the inter-model spread.The relatively small inter-model spread during summer is caused by the cancellation of the inter-model spread in ice-albedo feedback with that in the oceanic heat storage term.展开更多
A lunar geologic map at a scale of 1：5000000 was finished in the 1970s by the National Aeronautics and Space Administration, U.S U.S. Geological Survey. Department of the Interior, Till now, the landform classificati...A lunar geologic map at a scale of 1：5000000 was finished in the 1970s by the National Aeronautics and Space Administration, U.S U.S. Geological Survey. Department of the Interior, Till now, the landform classification system and lunar morphologic mapping have not been clarified. The work aims to put forward a new landform classification system and to obtain index and map in the Sheet H010. Some key morphologic features of lunar surface were compared with those of the Earth. This research is very important for whole lunar morphologic mapping and unraveling evolutionary progress.展开更多
In this paper, the authors establish the LV-mapping properties for a class of singular integrals along surfaces in Rn of the form {Ф（lul）u＇ ： u ε ]t^n} as well as the related maimal operators provided that the f...In this paper, the authors establish the LV-mapping properties for a class of singular integrals along surfaces in Rn of the form {Ф（lul）u＇ ： u ε ]t^n} as well as the related maimal operators provided that the function Ф satisfies certain oscillatory integral estimates of Van der Corput type, and the integral kernels are given by the radial function h E ε△γ（R＋） for γ 〉 1 and the sphere function ΩεFβ（S^n-1） for someβ 〉 0 which is distinct from HI（Sn-1）.展开更多
In recent years,as intelligent transportation systems(ITS)such as autonomous driving and advanced driver-assistance systems have become more popular,there has been a rise in the need for different sources of traffic s...In recent years,as intelligent transportation systems(ITS)such as autonomous driving and advanced driver-assistance systems have become more popular,there has been a rise in the need for different sources of traffic situation data.The classification of the road surface type,also known as the RST,is among the most essential of these situational data and can be utilized across the entirety of the ITS domain.Recently,the benefits of deep learning(DL)approaches for sensor-based RST classification have been demonstrated by automatic feature extraction without manual methods.The ability to extract important features is vital in making RST classification more accurate.This work investigates the most recent advances in DL algorithms for sensor-based RST classification and explores appropriate feature extraction models.We used different convolutional neural networks to understand the functional architecture better;we constructed an enhanced DL model called SE-ResNet,which uses residual connections and squeeze-and-excitation mod-ules to improve the classification performance.Comparative experiments with a publicly available benchmark dataset,the passive vehicular sensors dataset,have shown that SE-ResNet outperforms other state-of-the-art models.The proposed model achieved the highest accuracy of 98.41%and the highest F1-score of 98.19%when classifying surfaces into segments of dirt,cobblestone,or asphalt roads.Moreover,the proposed model significantly outperforms DL networks(CNN,LSTM,and CNN-LSTM).The proposed RE-ResNet achieved the classification accuracies of asphalt roads at 98.98,cobblestone roads at 97.02,and dirt roads at 99.56%,respectively.展开更多
Coralline algae are globally distributed calcifying species and play critical ecological roles to marine ecosystems by contributing significantly to their structural complexity and diversity.Thallus surface types of h...Coralline algae are globally distributed calcifying species and play critical ecological roles to marine ecosystems by contributing significantly to their structural complexity and diversity.Thallus surface types of historical samples in Sanya coral reef reserve were studied based on the scanning electron microscope(SEM)method.Our results show six thallus surface types within the study area:Corallina-type,Jania-type,Leptophytum-type,Phymatolithon-type,Pneophyllum-type,and Spongites-type.The Phymatolithon-type is the dominant surface type in Sanya reefs.Two new record species in the region are described:Amphiroa beauvoisii and Neogoniolithon setchellii.Although thallus surface types provide useful diagnostics characters for distinguishing coralline algae at tribe or subfamily level,species identification needs to refer to the reproductive features.This is the first surface study of coralline algae in the South China Sea.This result provides the baseline data needed for the monitoring and management of reef-building organisms of coral reef in China.展开更多
The effects of indium composition in InGaAs interlayer and on optical properties of GaSb/InGaAs QD material on morphology of GaSb/InGaAs quantum dots （QDs） system are studied. AFM images show that the change of the ...The effects of indium composition in InGaAs interlayer and on optical properties of GaSb/InGaAs QD material on morphology of GaSb/InGaAs quantum dots （QDs） system are studied. AFM images show that the change of the indium composition in InGaAs interlayer can alter the GaSb QD morphology. It is found that low indium composition in InGaAs interlayer can promote the formation of QDs, while high indium composition can inhibit the formation of QDs. The photoluminescence （PL） spectra of GaSb/InGaAs QDs at 8 K under low excitation power indicate that the third root of the excitation power is linear with the peak position, which provides a direct evidence for their luminescence belonging to type-Ⅱ material optical transition. The PL spectra at 8 K under an excitation power of 90row show that the optical properties of GaSb/InGaAs QD material system can be affected by the indium composition in the InGaAs interlayer, and the PL peak position is linear with the indium composition. The optical properties of GaSb/InGaAs QDs can be improved by adjusting the indium composition in the InGaAs interlayer.展开更多
Cloud Masking is one of the most essential products for satellite remote sensing and downstream applications.This study develops machine learning-based(ML-based)cloud detection algorithms using spectral observations f...Cloud Masking is one of the most essential products for satellite remote sensing and downstream applications.This study develops machine learning-based(ML-based)cloud detection algorithms using spectral observations for the Advanced Himawari Imager(AHI)onboard the Himawari-8 geostationary satellite.Collocated active observations from Cloud-Aerosol Lidar with Orthogonal Polarization(CALIOP)are used to provide reference labels for model development and validation.We introduce both daytime and nighttime algorithms that differ according to whether solar band observations are included,and the artificial neural network(ANN)and random forest(RF)techniques are adopted for comparison.To eliminate the influences of surface conditions on cloud detection,we introduce three models with different treatments of the surface.Instead of developing independent ML-based algorithms,we add surface variables in a binary way that enhances the ML-based algorithm accuracy by~5%.Validated against CALIOP observations,we find that our daytime RF-based algorithm outperforms the AHI operational algorithm by improving the accuracy of cloudy pixel detection by~5%,while at the same time,reducing misjudgment by~3%.The nighttime model with only infrared observations is also slightly better than the AHI operational product but may tend to overestimate cloudy pixels.Overall,our ML-based algorithms can serve as a reliable method to provide cloud mask results for both daytime and nighttime AHI observations.We furthermore suggest treating the surface with a set of independent variables for future ML-based algorithm development.展开更多
Dew is an important supplement water source in arid and semi-arid areas. In order to determine the dew formation on different kinds of soils associated with various shrub species and microhabitats, we performed measur...Dew is an important supplement water source in arid and semi-arid areas. In order to determine the dew formation on different kinds of soils associated with various shrub species and microhabitats, we performed measurement of accumulated dew formation amount and duration in October 2009 in a revegetation-stabilized arid desert ecosystem in Shapotou area, northern China. The results indicated that the accumulated dew formation amount was four times larger at open spaces as compared to under the canopy, and it was nearly twice as much under living Artemisia ordosica plants（L.A.） as compared to under living Caragana korshinskii plants（L.C.）. The opposite characteristics were found for dew duration between different microhabitats. Dew amounts at different vertical heights around the shrub stands were in the order of 50 cm above the canopy〉the canopy edge〉under the canopy. Dew amount continued to increase after dawn, and the proportion of average accumulated dew amount after dawn accounting for the average maximum amount increased from above the canopy to under the canopy. Dew formation duration after sunrise accounted for more than 50% of the total formation duration during the day time. Contrary to the distribution characteristics of dew amount, dew duration after dawn and total dew formation duration during the day time were both highest under the canopy, followed by at the canopy edge and then at 50 cm above the canopy. The portion of dew duration after dawn accounting for the total dew duration during the day time increased from above the canopy to under the canopy. From these results, we may conclude that dew availability as a supplemental water resource for improving the microhabitats in water-limited arid ecosystems is position dependent especially for the plant microhabitats at different stands layers.展开更多
Spectral remote sensing technique is usually used to monitor flood and waterlogging disaster.Although spectral remote sensing data have many advantages for ground information observation,such as real time and high spa...Spectral remote sensing technique is usually used to monitor flood and waterlogging disaster.Although spectral remote sensing data have many advantages for ground information observation,such as real time and high spatial resolution,they are often interfered by clouds,haze and rain.As a result,it is very difficult to retrieve ground information from spectral remote sensing data under those conditions.Compared with spectral remote sensing tech-nique,passive microwave remote sensing technique has obvious superiority in most weather conditions.However,the main drawback of passive microwave remote sensing is the extreme low spatial resolution.Considering the wide ap-plication of the Advanced Microwave Scanning Radiometer-Earth Observing System(AMSR-E) data,an AMSR-E data unmixing method was proposed in this paper based on Bellerby's algorithm.By utilizing the surface type classifi-cation results with high spatial resolution,the proposed unmixing method can obtain the component brightness tem-perature and corresponding spatial position distribution,which effectively improve the spatial resolution of passive microwave remote sensing data.Through researching the AMSR-E unmixed data of Yongji County,Jilin Provinc,Northeast China after the worst flood and waterlogging disaster occurred on July 28,2010,the experimental results demonstrated that the AMSR-E unmixed data could effectively evaluate the flood and waterlogging disaster.展开更多
With the launch of the Joint Polar Satellite System(JPSS)/Suomi National Polar-orbiting Partnership(S-NPP)satellite in October 2011,many of the terrestrial remote sensing products generated from Moderate Resolution Im...With the launch of the Joint Polar Satellite System(JPSS)/Suomi National Polar-orbiting Partnership(S-NPP)satellite in October 2011,many of the terrestrial remote sensing products generated from Moderate Resolution Imaging Spectroradiometer(MODIS),such as the global land cover map,have been inherited and expanded into the JPSS/S-NPP mission using the new Visible Infrared Imaging Radiometer Suite(VIIRS)data.In this study,an improved algorithm including the use of a new classifier support vector machines(SVM)classifier was proposed to produce VIIRS surface type maps.In addition to the new classification algorithm,a new post-processing strategy involving the use of new ancillary data to refine the classification output is implemented.As a result,the new global International Geosphere-Biosphere Programme(IGBP)map based on the 2014 VIIRS surface reflectance data was generated with a 78.5±0.6% overall classification accuracy.The new map was compared to a previously delivered VIIRS surface type map,and to the MODIS land cover product.Validation results including the error matrix,overall accuracy,and the user’s and producer’s accuracy suggest the new global surface type map provides similar classification accuracy compared to the old VIIRS surface type map,with higher accuracy achieved in agricultural types.展开更多
Spaceborne photon-counting LiDAR is significantly affected by noise,and existing denoising algorithms cannot be universally adapted to different surface types and topographies under all observation conditions.Accordin...Spaceborne photon-counting LiDAR is significantly affected by noise,and existing denoising algorithms cannot be universally adapted to different surface types and topographies under all observation conditions.Accordingly,a new denoising method is presented to extract signal photons adaptively.The method includes two steps.First,the local neighborhood radius is calculated according to photons’density,then thefirst-step denoising process is completed via photons’curvature feature based on KNN search and covariance matrix.Second,the local photonfiltering direction and threshold are obtained based on thefirst-step denoising results by RANSAC and elevation frequency histogram,and the local dense noise photons that thefirst-step cannot be identified are further eliminated.The following results are drawn:(1)experimental results on MATLAS with different topographies indicate that the average accuracy of second-step denoising exceeds 0.94,and the accuracy is effectively improves with the number of denoising times;(2)experiments on ICESat-2 under different observation conditions demonstrate that the algorithm can accurately identify signal photons in different surface types and topographies.Overall,the proposed algorithm has good adaptability and robustness for adaptive denoising of large-scale photons,and the denoising results can provide more reasonable and reliable data for sustainable urban development.展开更多
In this study, Al/TiO2/Al2O3/p-Si was fabricated as a gas sensor. TiO2 and Al2O3 were grown by Atomic Layer Deposition method. The prepared film was tested in various gas concentrations at different operating temperat...In this study, Al/TiO2/Al2O3/p-Si was fabricated as a gas sensor. TiO2 and Al2O3 were grown by Atomic Layer Deposition method. The prepared film was tested in various gas concentrations at different operating temperatures ranging between 27 ℃ to 177 ℃. The sensitivity increases with increasing gas concentration and operating temperature which have a direct effect on sensing surface. The gas sensing mechanism could be explained with the surface controlled type based on the change of the electrical conductance of the semiconducting material. This mechanism is controlled by CO molecules and the amount of chemisorbed oxygen on the surface which is associated with temperature. Sample exhibits the basic parameters for gas sensors applications which are good stability, reproducibility and high sensitivity to CO gas which are. In addition, the response and recovery times are measured 19 and 26 s, respectively.展开更多
In this paper,we give certain homotopy and diffeomorphism versions as a generalization to an earlier result due to W.S.Cheung,Bun Wong and Stephen S.T.Yau concerning a local rigidity problem of the tangent bundle over...In this paper,we give certain homotopy and diffeomorphism versions as a generalization to an earlier result due to W.S.Cheung,Bun Wong and Stephen S.T.Yau concerning a local rigidity problem of the tangent bundle over compact surfaces of general type.展开更多
Let S be a minimal surface of general type with pg(S) = 0 and K_S^2= 4. Assume the bicanonical map ψ of S is a morphism of degree 4 such that the image of ψ is smooth. Then we prove that the surface S is a Burniat ...Let S be a minimal surface of general type with pg(S) = 0 and K_S^2= 4. Assume the bicanonical map ψ of S is a morphism of degree 4 such that the image of ψ is smooth. Then we prove that the surface S is a Burniat surface with K^2= 4 and of non nodal type.展开更多
We carry out an analysis of the canonical system of a minimal complex surface S of general type with irregularity q > 0.Using this analysis,we are able to sharpen in the case q > 0 the well-known Castelnuovo ine...We carry out an analysis of the canonical system of a minimal complex surface S of general type with irregularity q > 0.Using this analysis,we are able to sharpen in the case q > 0 the well-known Castelnuovo inequality KS2≥3pg(S) + q(S)-7.Then we turn to the study of surfaces with pg=2q-3 and no fibration onto a curve of genus > 1.We prove that for q≥6 the canonical map is birational.Combining this result with the analysis of the canonical system,we also prove the inequality:KS2≥7χ(S) + 2.This improves an earlier result of Mendes Lopes and Pardini (2010).展开更多
High-resolution surface air temperature data are critical to regional climate modeling in terms of energy balance,urban climate change,and so on.This study demonstrates the feasibility of using Moderate Resolution Ima...High-resolution surface air temperature data are critical to regional climate modeling in terms of energy balance,urban climate change,and so on.This study demonstrates the feasibility of using Moderate Resolution Imaging Spectroradiometer（MODIS）land surface temperature（LST）to estimate air temperature at a high resolution over the Yangtze River Delta region,China.It is found that daytime LST is highly correlated with maximum air temperature,and the linear regression coefficients vary with the type of land surface.The air temperature at a resolution of 1 km is estimated from the MODIS LST with linear regression models.The estimated air temperature shows a clear spatial structure of urban heat islands.Spatial patterns of LST and air temperature differences are detected,indicating maximum differences over urban and forest regions during summer.Validations are performed with independent data samples,demonstrating that the mean absolute error of the estimated air temperature is approximately 2.5°C,and the uncertainty is about 3.1°C,if using all valid LST data.The error is reduced by 0.4°C（15%）if using best-quality LST with errors of less than 1 K.The estimated high-resolution air temperature data have great potential to be used in validating high-resolution climate models and other regional applications.展开更多
The effect of sealed or unsealed road pavements on motorist’s injury severities has not been extensively explored.This study collected a four-year crash dataset(2015–2018)from South Australia to explore this issue.T...The effect of sealed or unsealed road pavements on motorist’s injury severities has not been extensively explored.This study collected a four-year crash dataset(2015–2018)from South Australia to explore this issue.The data shows 3,812 and 1,086 crashes at sealed and unsealed pavement surfaces,respectively,during those years.This study examines the consequence of sealed and unsealed pavements on driver injury severity outcomes of motor vehicle crashes.A mixed logit model was developed by accounting for heterogeneity in means and variances of the random parameters.The variables were distributed among several categories:driver,temporal,spatial,roadway characteristics,crash type,vehicle type,and vehicle movement.Four random parameters were observed in the sealed model,whereas five parameters were in the unsealed one.Moreover,the sealed pavements model showed substantial heterogeneity in means of four of the random parameters,while the unsealed pavements model has some heterogeneity in both means and variances of some of the random parameters.Marginal effect results indicate that two indicator variables have enlarged the likelihood of driver severe injury consequences in sealed,alcohol involvement and posted speed limit>100 km/hr.Additionally,four other significant variables sustain the probability of severe injury outcomes at unsealed pavement like male drivers,middle-aged drivers,rollover crash types,and crashes at straight roads.Based on these variables,various countermeasures were recommended to enhance the safety of both types of pavements.展开更多
基金the National Natural Science Foundation of China(Grant No.41922044)the National Key Research and Development Program of China(Grants Nos.2019YFA0607000,2022YFE0106300)+2 种基金the National Natural Sci-ence Foundation of China(Grants Nos.42075028 and 42222502)Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(Grant No.SML2021SP302)the fundamental research funds for the Norges Forskningsråd(Grant No.328886).
文摘A robust phenomenon termed the Arctic Amplification(AA)refers to the stronger warming taking place over the Arctic compared to the global mean.The AA can be confirmed through observations and reproduced in climate model simulations and shows significant seasonality and inter-model spread.This study focuses on the influence of surface type on the seasonality of AA and its inter-model spread by dividing the Arctic region into four surface types:ice-covered,ice-retreat,ice-free,and land.The magnitude and inter-model spread of Arctic surface warming are calculated from the difference between the abrupt-4×CO_(2)and pre-industrial experiments of 17 CMIP6 models.The change of effective thermal inertia(ETI)in response to the quadrupling of CO_(2) forcing is the leading mechanism for the seasonal energy transfer mechanism,which acts to store heat temporarily in summer and then release it in winter.The ETI change is strongest over the ice-retreat region,which is also responsible for the strongest AA among the four surface types.The lack of ETI change explains the nearly uniform warming pattern across seasons over the ice-free(ocean)region.Compared to other regions,the ice-covered region shows the maximum inter-model spread in JFM,resulting from a stronger inter-model spread in the oceanic heat storage term.However,the weaker upward surface turbulent sensible and latent heat fluxes tend to suppress the inter-model spread.The relatively small inter-model spread during summer is caused by the cancellation of the inter-model spread in ice-albedo feedback with that in the oceanic heat storage term.
基金supported by the National Natural Science Foundation of China(grant No.41571388)
文摘A lunar geologic map at a scale of 1：5000000 was finished in the 1970s by the National Aeronautics and Space Administration, U.S U.S. Geological Survey. Department of the Interior, Till now, the landform classification system and lunar morphologic mapping have not been clarified. The work aims to put forward a new landform classification system and to obtain index and map in the Sheet H010. Some key morphologic features of lunar surface were compared with those of the Earth. This research is very important for whole lunar morphologic mapping and unraveling evolutionary progress.
基金Supported by the National Natural Science Foundation of China(11071200,11371295)
文摘In this paper, the authors establish the LV-mapping properties for a class of singular integrals along surfaces in Rn of the form {Ф（lul）u＇ ： u ε ]t^n} as well as the related maimal operators provided that the function Ф satisfies certain oscillatory integral estimates of Van der Corput type, and the integral kernels are given by the radial function h E ε△γ（R＋） for γ 〉 1 and the sphere function ΩεFβ（S^n-1） for someβ 〉 0 which is distinct from HI（Sn-1）.
基金funded by National Research Council of Thailand (NRCT):An Integrated Road Safety Innovations of Pedestrian Crossing for Mortality and Injuries Reduction Among All Groups of Road Users,Contract No.N33A650757supported by the Thailand Science Research and Innovation Fund+1 种基金the University of Phayao (Grant No.FF66-UoE001)King Mongkut’s University of Technology North Bangkok underContract No.KMUTNB-66-KNOW-05.
文摘In recent years,as intelligent transportation systems(ITS)such as autonomous driving and advanced driver-assistance systems have become more popular,there has been a rise in the need for different sources of traffic situation data.The classification of the road surface type,also known as the RST,is among the most essential of these situational data and can be utilized across the entirety of the ITS domain.Recently,the benefits of deep learning(DL)approaches for sensor-based RST classification have been demonstrated by automatic feature extraction without manual methods.The ability to extract important features is vital in making RST classification more accurate.This work investigates the most recent advances in DL algorithms for sensor-based RST classification and explores appropriate feature extraction models.We used different convolutional neural networks to understand the functional architecture better;we constructed an enhanced DL model called SE-ResNet,which uses residual connections and squeeze-and-excitation mod-ules to improve the classification performance.Comparative experiments with a publicly available benchmark dataset,the passive vehicular sensors dataset,have shown that SE-ResNet outperforms other state-of-the-art models.The proposed model achieved the highest accuracy of 98.41%and the highest F1-score of 98.19%when classifying surfaces into segments of dirt,cobblestone,or asphalt roads.Moreover,the proposed model significantly outperforms DL networks(CNN,LSTM,and CNN-LSTM).The proposed RE-ResNet achieved the classification accuracies of asphalt roads at 98.98,cobblestone roads at 97.02,and dirt roads at 99.56%,respectively.
基金National Key Research and Development Program of China(2017YFC0506301)National Natural Science Foundation of China(41306144,41676150)+1 种基金Strategic Priority Research Program of the Chinese Academy of Sciences(Grant XDA13020402)Guangdong Basic and Applied Basic Research Foundation,under contract No.2019A1515011532.
文摘Coralline algae are globally distributed calcifying species and play critical ecological roles to marine ecosystems by contributing significantly to their structural complexity and diversity.Thallus surface types of historical samples in Sanya coral reef reserve were studied based on the scanning electron microscope(SEM)method.Our results show six thallus surface types within the study area:Corallina-type,Jania-type,Leptophytum-type,Phymatolithon-type,Pneophyllum-type,and Spongites-type.The Phymatolithon-type is the dominant surface type in Sanya reefs.Two new record species in the region are described:Amphiroa beauvoisii and Neogoniolithon setchellii.Although thallus surface types provide useful diagnostics characters for distinguishing coralline algae at tribe or subfamily level,species identification needs to refer to the reproductive features.This is the first surface study of coralline algae in the South China Sea.This result provides the baseline data needed for the monitoring and management of reef-building organisms of coral reef in China.
基金Supported by the Science and Technology Planning Projects of Guangdong Province under Grant Nos 2014B050505020,2015B010114007 and 2014B090904045the Research Fund for the Doctoral Program of Higher Education of China under Grant No 20134407110008+1 种基金the Guangzhou Science and Technology Project of Guangdong Province under Grant No 2016201604030027the Zhongshan Science and Technology Project of Guangdong Province under Grant No 2013B3FC0003
文摘The effects of indium composition in InGaAs interlayer and on optical properties of GaSb/InGaAs QD material on morphology of GaSb/InGaAs quantum dots （QDs） system are studied. AFM images show that the change of the indium composition in InGaAs interlayer can alter the GaSb QD morphology. It is found that low indium composition in InGaAs interlayer can promote the formation of QDs, while high indium composition can inhibit the formation of QDs. The photoluminescence （PL） spectra of GaSb/InGaAs QDs at 8 K under low excitation power indicate that the third root of the excitation power is linear with the peak position, which provides a direct evidence for their luminescence belonging to type-Ⅱ material optical transition. The PL spectra at 8 K under an excitation power of 90row show that the optical properties of GaSb/InGaAs QD material system can be affected by the indium composition in the InGaAs interlayer, and the PL peak position is linear with the indium composition. The optical properties of GaSb/InGaAs QDs can be improved by adjusting the indium composition in the InGaAs interlayer.
基金financially supported by the National Key Research and Development Program of China (Grant No. 2018YFC1506502)National Natural Science Foundation of China (Grant No. 41975025)+2 种基金Natural Science Foundation of Jiangsu Province (Grant No. BK20190093)Defense Industrial Technoloy Development Program“Qinlan” program of Jiangsu Province
文摘Cloud Masking is one of the most essential products for satellite remote sensing and downstream applications.This study develops machine learning-based(ML-based)cloud detection algorithms using spectral observations for the Advanced Himawari Imager(AHI)onboard the Himawari-8 geostationary satellite.Collocated active observations from Cloud-Aerosol Lidar with Orthogonal Polarization(CALIOP)are used to provide reference labels for model development and validation.We introduce both daytime and nighttime algorithms that differ according to whether solar band observations are included,and the artificial neural network(ANN)and random forest(RF)techniques are adopted for comparison.To eliminate the influences of surface conditions on cloud detection,we introduce three models with different treatments of the surface.Instead of developing independent ML-based algorithms,we add surface variables in a binary way that enhances the ML-based algorithm accuracy by~5%.Validated against CALIOP observations,we find that our daytime RF-based algorithm outperforms the AHI operational algorithm by improving the accuracy of cloudy pixel detection by~5%,while at the same time,reducing misjudgment by~3%.The nighttime model with only infrared observations is also slightly better than the AHI operational product but may tend to overestimate cloudy pixels.Overall,our ML-based algorithms can serve as a reliable method to provide cloud mask results for both daytime and nighttime AHI observations.We furthermore suggest treating the surface with a set of independent variables for future ML-based algorithm development.
基金financially supported by the National Natural Science Foundation of China (41201085)the 100 Talents Program of the Chinese Academy of Sciences
文摘Dew is an important supplement water source in arid and semi-arid areas. In order to determine the dew formation on different kinds of soils associated with various shrub species and microhabitats, we performed measurement of accumulated dew formation amount and duration in October 2009 in a revegetation-stabilized arid desert ecosystem in Shapotou area, northern China. The results indicated that the accumulated dew formation amount was four times larger at open spaces as compared to under the canopy, and it was nearly twice as much under living Artemisia ordosica plants（L.A.） as compared to under living Caragana korshinskii plants（L.C.）. The opposite characteristics were found for dew duration between different microhabitats. Dew amounts at different vertical heights around the shrub stands were in the order of 50 cm above the canopy〉the canopy edge〉under the canopy. Dew amount continued to increase after dawn, and the proportion of average accumulated dew amount after dawn accounting for the average maximum amount increased from above the canopy to under the canopy. Dew formation duration after sunrise accounted for more than 50% of the total formation duration during the day time. Contrary to the distribution characteristics of dew amount, dew duration after dawn and total dew formation duration during the day time were both highest under the canopy, followed by at the canopy edge and then at 50 cm above the canopy. The portion of dew duration after dawn accounting for the total dew duration during the day time increased from above the canopy to under the canopy. From these results, we may conclude that dew availability as a supplemental water resource for improving the microhabitats in water-limited arid ecosystems is position dependent especially for the plant microhabitats at different stands layers.
基金Under the auspices of National Natural Science Foundation of China (No. 40971189)Knowledge Innovation Programs of Chinese Academy of Sciences (No. KZCX2-YW-340)China Postdoctoral Science Foundation (No. 20100471276)
文摘Spectral remote sensing technique is usually used to monitor flood and waterlogging disaster.Although spectral remote sensing data have many advantages for ground information observation,such as real time and high spatial resolution,they are often interfered by clouds,haze and rain.As a result,it is very difficult to retrieve ground information from spectral remote sensing data under those conditions.Compared with spectral remote sensing tech-nique,passive microwave remote sensing technique has obvious superiority in most weather conditions.However,the main drawback of passive microwave remote sensing is the extreme low spatial resolution.Considering the wide ap-plication of the Advanced Microwave Scanning Radiometer-Earth Observing System(AMSR-E) data,an AMSR-E data unmixing method was proposed in this paper based on Bellerby's algorithm.By utilizing the surface type classifi-cation results with high spatial resolution,the proposed unmixing method can obtain the component brightness tem-perature and corresponding spatial position distribution,which effectively improve the spatial resolution of passive microwave remote sensing data.Through researching the AMSR-E unmixed data of Yongji County,Jilin Provinc,Northeast China after the worst flood and waterlogging disaster occurred on July 28,2010,the experimental results demonstrated that the AMSR-E unmixed data could effectively evaluate the flood and waterlogging disaster.
基金supported by the National Oceanic and Atmospheric Administration(NOAA)JPSS programThe funding was managed by Cooperative Institute for Climate&Satellites-Maryland(CICS-MD)with award#NA14NES4320003.
文摘With the launch of the Joint Polar Satellite System(JPSS)/Suomi National Polar-orbiting Partnership(S-NPP)satellite in October 2011,many of the terrestrial remote sensing products generated from Moderate Resolution Imaging Spectroradiometer(MODIS),such as the global land cover map,have been inherited and expanded into the JPSS/S-NPP mission using the new Visible Infrared Imaging Radiometer Suite(VIIRS)data.In this study,an improved algorithm including the use of a new classifier support vector machines(SVM)classifier was proposed to produce VIIRS surface type maps.In addition to the new classification algorithm,a new post-processing strategy involving the use of new ancillary data to refine the classification output is implemented.As a result,the new global International Geosphere-Biosphere Programme(IGBP)map based on the 2014 VIIRS surface reflectance data was generated with a 78.5±0.6% overall classification accuracy.The new map was compared to a previously delivered VIIRS surface type map,and to the MODIS land cover product.Validation results including the error matrix,overall accuracy,and the user’s and producer’s accuracy suggest the new global surface type map provides similar classification accuracy compared to the old VIIRS surface type map,with higher accuracy achieved in agricultural types.
基金supported by the National Key R&D Program of China under[grant number 2021YFF0704600]the National Natural Science Foundation of China under[grant number 42171352,42271365,U22A20566]the High-Level Talent Aggregation Project in Hunan Province,China-Innovation Team under[grant number 2019RS1060].
文摘Spaceborne photon-counting LiDAR is significantly affected by noise,and existing denoising algorithms cannot be universally adapted to different surface types and topographies under all observation conditions.Accordingly,a new denoising method is presented to extract signal photons adaptively.The method includes two steps.First,the local neighborhood radius is calculated according to photons’density,then thefirst-step denoising process is completed via photons’curvature feature based on KNN search and covariance matrix.Second,the local photonfiltering direction and threshold are obtained based on thefirst-step denoising results by RANSAC and elevation frequency histogram,and the local dense noise photons that thefirst-step cannot be identified are further eliminated.The following results are drawn:(1)experimental results on MATLAS with different topographies indicate that the average accuracy of second-step denoising exceeds 0.94,and the accuracy is effectively improves with the number of denoising times;(2)experiments on ICESat-2 under different observation conditions demonstrate that the algorithm can accurately identify signal photons in different surface types and topographies.Overall,the proposed algorithm has good adaptability and robustness for adaptive denoising of large-scale photons,and the denoising results can provide more reasonable and reliable data for sustainable urban development.
文摘In this study, Al/TiO2/Al2O3/p-Si was fabricated as a gas sensor. TiO2 and Al2O3 were grown by Atomic Layer Deposition method. The prepared film was tested in various gas concentrations at different operating temperatures ranging between 27 ℃ to 177 ℃. The sensitivity increases with increasing gas concentration and operating temperature which have a direct effect on sensing surface. The gas sensing mechanism could be explained with the surface controlled type based on the change of the electrical conductance of the semiconducting material. This mechanism is controlled by CO molecules and the amount of chemisorbed oxygen on the surface which is associated with temperature. Sample exhibits the basic parameters for gas sensors applications which are good stability, reproducibility and high sensitivity to CO gas which are. In addition, the response and recovery times are measured 19 and 26 s, respectively.
文摘In this paper,we give certain homotopy and diffeomorphism versions as a generalization to an earlier result due to W.S.Cheung,Bun Wong and Stephen S.T.Yau concerning a local rigidity problem of the tangent bundle over compact surfaces of general type.
基金supported by Shanghai Center for Mathematical Sciences
文摘Let S be a minimal surface of general type with pg(S) = 0 and K_S^2= 4. Assume the bicanonical map ψ of S is a morphism of degree 4 such that the image of ψ is smooth. Then we prove that the surface S is a Burniat surface with K^2= 4 and of non nodal type.
基金supported by FCT (Portugal) through program POCTI/FEDER and Project PTDC/MAT/099275/2008by MIUR (Italy) through project PRIN 2007 "Spazi di moduli e teorie di Lie"
文摘We carry out an analysis of the canonical system of a minimal complex surface S of general type with irregularity q > 0.Using this analysis,we are able to sharpen in the case q > 0 the well-known Castelnuovo inequality KS2≥3pg(S) + q(S)-7.Then we turn to the study of surfaces with pg=2q-3 and no fibration onto a curve of genus > 1.We prove that for q≥6 the canonical map is birational.Combining this result with the analysis of the canonical system,we also prove the inequality:KS2≥7χ(S) + 2.This improves an earlier result of Mendes Lopes and Pardini (2010).
基金Supported by the National Natural Science Foundation of China(41230528)National(Key)Basic Research and Development(973)Program of China(2010CB428505)Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘High-resolution surface air temperature data are critical to regional climate modeling in terms of energy balance,urban climate change,and so on.This study demonstrates the feasibility of using Moderate Resolution Imaging Spectroradiometer（MODIS）land surface temperature（LST）to estimate air temperature at a high resolution over the Yangtze River Delta region,China.It is found that daytime LST is highly correlated with maximum air temperature,and the linear regression coefficients vary with the type of land surface.The air temperature at a resolution of 1 km is estimated from the MODIS LST with linear regression models.The estimated air temperature shows a clear spatial structure of urban heat islands.Spatial patterns of LST and air temperature differences are detected,indicating maximum differences over urban and forest regions during summer.Validations are performed with independent data samples,demonstrating that the mean absolute error of the estimated air temperature is approximately 2.5°C,and the uncertainty is about 3.1°C,if using all valid LST data.The error is reduced by 0.4°C（15%）if using best-quality LST with errors of less than 1 K.The estimated high-resolution air temperature data have great potential to be used in validating high-resolution climate models and other regional applications.
文摘The effect of sealed or unsealed road pavements on motorist’s injury severities has not been extensively explored.This study collected a four-year crash dataset(2015–2018)from South Australia to explore this issue.The data shows 3,812 and 1,086 crashes at sealed and unsealed pavement surfaces,respectively,during those years.This study examines the consequence of sealed and unsealed pavements on driver injury severity outcomes of motor vehicle crashes.A mixed logit model was developed by accounting for heterogeneity in means and variances of the random parameters.The variables were distributed among several categories:driver,temporal,spatial,roadway characteristics,crash type,vehicle type,and vehicle movement.Four random parameters were observed in the sealed model,whereas five parameters were in the unsealed one.Moreover,the sealed pavements model showed substantial heterogeneity in means of four of the random parameters,while the unsealed pavements model has some heterogeneity in both means and variances of some of the random parameters.Marginal effect results indicate that two indicator variables have enlarged the likelihood of driver severe injury consequences in sealed,alcohol involvement and posted speed limit>100 km/hr.Additionally,four other significant variables sustain the probability of severe injury outcomes at unsealed pavement like male drivers,middle-aged drivers,rollover crash types,and crashes at straight roads.Based on these variables,various countermeasures were recommended to enhance the safety of both types of pavements.
