With the large-scale deployment of satellite constellations such as Starlink and the rapid advancement of technologies including artificial intelligence (AI) and non-terrestrial networks (NTNs), the integration of hig...With the large-scale deployment of satellite constellations such as Starlink and the rapid advancement of technologies including artificial intelligence (AI) and non-terrestrial networks (NTNs), the integration of high, medium, and low Earth orbit satellite networks with terrestrial networks has become a critical direction for future communication technologies. The objective is to develop a space-terrestrial integrated 6G network that ensures ubiquitous connectivity and seamless services, facilitating intelligent interconnection and collaborative symbiosis among humans, machines, and objects. This integration has become a central focus of global technological innovation.展开更多
Climate change and anthropogenic activities have driven significant terrestrial water storage changes(TWSC)in the Three Rivers Source Region(TRSR),exerting profound impacts on freshwater availability across China and ...Climate change and anthropogenic activities have driven significant terrestrial water storage changes(TWSC)in the Three Rivers Source Region(TRSR),exerting profound impacts on freshwater availability across China and broader Asia.However,long-term TWSC characterization remains challenging due to limited observational data in this alpine region.Here,we integrate GRACE observations(2002-2020),ERA5-Land reanalysis,and GLDAS data to reconstruct TWSC using two methods:(1)the water balance method(PER)and(2)the component summation method(SS),applied to three input datasets(ERA5-Land,GLDAS,and their average,GLER).Comparative analysis reveals that the SS method applied to GL-ER yields the highest consistency with GRACE-derived TWSC.Using this optimal approach,we extend the analysis to 1951~2020,uncovering spatiotemporal TWSC patterns.Although annual TWSC trends appear negligible due to strong seasonality,we introduce the intra-year TWSC fluctuation(TWSCF)index to quantify cumulative variability.A significant(p<0.05)transition occurred in 1980,with TWSCF shifting from a declining trend(-0.39 mm/yr)to an increasing trend(0.56 mm/yr),primarily driven by soil moisture changes.However,Hurst exponent analysis suggests this upward trend may not persist.Drought and vegetation assessments indicate concurrent wetting and greening in the TRSR.TWSC correlates strongly with meteorological drought,acting as a reliable drought indicator while its linkage with vegetation dynamics suggests a potential contribution to greening.Our findings provide a robust framework for understanding long-term TWSC evolution and its hydrological-ecological interactions under climate change.展开更多
Branch angles are an important plant morphological trait affecting light interception within forest canopies.However,studies on branch angles have been limited due to the time-consuming nature of manual measurements u...Branch angles are an important plant morphological trait affecting light interception within forest canopies.However,studies on branch angles have been limited due to the time-consuming nature of manual measurements using a protractor.Terrestrial laser scanning(TLS),however,provides new opportunities to measure branch angles more efficiently.Despite this potential,studies validating branch angle measurements from TLS have been limited.Here,our aim is to evaluate both manual and automatic branch angle measurements of European beech from TLS data using traditional field-measurements with a protractor as a reference.We evaluated the accuracy of branch angle measurements based on four automated algorithms(aRchiQSM,TreeQSM,Laplacian,SemanticLaplacian)from TLS data.Additionally,we assessed different ways of manual branch angle measurements in the field.Our study was based on a dataset comprising 124 branch angles measured from six European beech in a European deciduous forest.Our results show that manual branch angle measurements from TLS data are in high agreement with the reference(root-mean-squared error,RMSE:[3.57°-4.18°],concordance correlation coefficient,CCC:[0.950.97])across different branch length positions.Automated algorithms also are in high agreement with the reference although RMSE is approximately twice as large compared to manual branch angle measurements from TLS(RMSE:[9.29°-10.55°],CCC:[0.830.86])with manual leaf points removal.When applying the automatic wood-leaf separation algorithm,the performance of the four methods declined significantly,with only approximately 20 branch angles successfully identified.Moreover,it is important to note that there is no influence of the measurement position(branch surface versus center)for branch angle measurements.However,for curved branches,the selection of branch measurement length significantly impacts the branch angle measurement.This study provides a comprehensive understanding of branch angle measurements in forests.We show that automated measurement methods based on TLS data of branch angles are a valuable tool to quantify branch angles at larger scales.展开更多
1.Introduction As a key development of the next-generation spatial information infrastructure,1the Satellite-Terrestrial Integrated Network(STIN)has become a strategic priority actively pursued by major spacefaring na...1.Introduction As a key development of the next-generation spatial information infrastructure,1the Satellite-Terrestrial Integrated Network(STIN)has become a strategic priority actively pursued by major spacefaring nations and regions,including the United States,Europe,China,and Russia.Specifically,Space X’s Starlink project has deployed over 6750 satellites,2while One Web has completed its initial phase of satellite constellation deployment with more than 600 satellites.展开更多
The rhenium-osmium(Re-Os)isotope system is a powerful tool for dating organic-rich sedimentary rocks,yet the mechanisms of Re and Os uptake and their fractionation in different types of organic matter remain poorly un...The rhenium-osmium(Re-Os)isotope system is a powerful tool for dating organic-rich sedimentary rocks,yet the mechanisms of Re and Os uptake and their fractionation in different types of organic matter remain poorly understood.Here,we investigate the role of terrestrial organic matter(e.g.,wood of the species Taxodium distichum and charcoal generated from the same species in the laboratory)in Re and Os enrichment and isotope fractionation through laboratory experiments.The results show that charcoal has a significantly higher capacity to uptake both Re(68-77 times greater)and Os(1.7-2.2 times higher)compared to wood,with charcoal preferentially accumulating Re over Os,leading to higher^(187)Re/^(188)Os ratios.These findings highlight the important contribution of terrestrial organic matter,particularly charcoal,to Re and Os concentrations and isotope fractionation in shales,and the importance of organic matter type for chelating Re and Os as previously discussed.Furthermore,we discuss the potential of using Re to track organic carbon weathering,noting that the coupled release of Re and organic carbon during weathering provides new insights into carbon cycling processes.展开更多
In this study,terrestrial laser scanning(TLS)is used to collect building data after the M_(s) 7.0 magnitude earthquake in Lushan,Sichuan,China in 2013 for analysis and research.The analysis focuses on extracting the t...In this study,terrestrial laser scanning(TLS)is used to collect building data after the M_(s) 7.0 magnitude earthquake in Lushan,Sichuan,China in 2013 for analysis and research.The analysis focuses on extracting the tilt and deformation of masonry buildings that are difficult to identify through visual inspection in basically intact,slightly damaged and moderately damaged masonry buildings,to solve the problem of ambiguous identification of damage.A quantitative analysis of the determination indexes of the degree of earthquake damage was carried out,and the numerical characteristics parameters such as the curvature of the wall point cloud proximity,angle,contour of the fitted plane of the point cloud,verticality(flatness)of the wall,standard deviation of the profile and angle of the profile were established to determine the degree of earthquake damage to buildings based on LiDAR data.The development of quantitative determination indexes for the degree of earthquake damage of buildings in this study has important application value for LiDAR data in the identification and extraction of earthquake damage information and damage level determination.展开更多
In this paper,we propose a joint power and frequency allocation algorithm considering interference protection in the integrated satellite and terrestrial network(ISTN).We efficiently utilize spectrum resources by allo...In this paper,we propose a joint power and frequency allocation algorithm considering interference protection in the integrated satellite and terrestrial network(ISTN).We efficiently utilize spectrum resources by allowing user equipment(UE)of terrestrial networks to share frequencies with satellite networks.In order to protect the satellite terminal(ST),the base station(BS)needs to control the transmit power and frequency resources of the UE.The optimization problem involves maximizing the achievable throughput while satisfying the interference protection constraints of the ST and the quality of service(QoS)of the UE.However,this problem is highly nonconvex,and we decompose it into power allocation and frequency resource scheduling subproblems.In the power allocation subproblem,we propose a power allocation algorithm based on interference probability(PAIP)to address channel uncertainty.We obtain the suboptimal power allocation solution through iterative optimization.In the frequency resource scheduling subproblem,we develop a heuristic algorithm to handle the non-convexity of the problem.The simulation results show that the combination of power allocation and frequency resource scheduling algorithms can improve spectrum utilization.展开更多
The present study was conducted to examine the trophic transfer of potentially toxic elements(PTEs)in a closed arsenic mine.Eight PTEs in a soil-plant-leaf litter-earthworm-top predators(free-range local chicken and w...The present study was conducted to examine the trophic transfer of potentially toxic elements(PTEs)in a closed arsenic mine.Eight PTEs in a soil-plant-leaf litter-earthworm-top predators(free-range local chicken and wild passerine bird)system were analyzed for nitrogen and carbon stable isotopes,PTE concentrations,bioaccumulation factors(BAFs),and transfer factors(TFs).The PTE concentrations in soils from mining areas were generally higher than a adjacent controlled area,with As and Cd in soils showing the prominent compared to other six PTEs,as seen for the indices of geo-accumulation index(I_(geo)),pollution index(PI)and potential ecological risk index(RI).The relatively high BAF and TF values suggested a distinct biotransfer of PTEs along the soil-plant-leaf litter-earthworm system.BAFs were mostly<1 except in earthworms,indicating that earthworms had a strong capacity to take up these metals.The TFs varied both among PTEs and organism’s species,e.g.,the transfer capacities of As in Pteris vittata and Pteris cretica,Cd in Miscanthus sinensis,and Pb,Cr and Mn in moss were the highest.For local free-range chicken and wild passerine bird,the concentrations of PTEs were higher in gastric contents and feather than in internal tissue(stomach,liver and heart),with lower contents in muscle and egg.Bioaccumulation of PTEs generally decreased from decomposer earthworms,to primary producer plants,to top predator,indicating a potential bio-dilution tendency in higher trophic levels in the terrestrial food chain.展开更多
With the advent of the digital era,the field of communications is undergoing profound transformation.Among the most groundbreaking developments is the emergence of non-terrestrial networks(NTN),which represent not onl...With the advent of the digital era,the field of communications is undergoing profound transformation.Among the most groundbreaking developments is the emergence of non-terrestrial networks(NTN),which represent not only a technological leap forward but also a major trend shaping the future of global connectivity.As a layered heterogeneous network,NTN integrates multiple aerial platforms—including satellites,high-altitude platform systems(HAPS),and unmanned aerial systems(UAS)—to provide flexible and composable solutions aimed at achieving seamless worldwide communication coverage.展开更多
The transpiration-to-evapotranspiration ratio(T/ET)is a crucial indicator of the carbon-water cycle and energy balance.Despite the marked seasonality of warming and greening patterns,the differential responses of T/ET...The transpiration-to-evapotranspiration ratio(T/ET)is a crucial indicator of the carbon-water cycle and energy balance.Despite the marked seasonality of warming and greening patterns,the differential responses of T/ET to environmental changes across the seasons remain unclear.To address this,we employed a model-data fusion method,integrating the Priestley–Taylor Jet Propulsion Lab model with observational datasets,to analyze the seasonal trends of T/ET in China’s terrestrial ecosystems from 1981 to 2021.The results showed that T/ET significantly increased in spring,summer,and autumn,with growth rates of 0.0018 a^(–1)(p<0.01),0.0024 a^(–1)(p<0.01),and 0.0013 a^(–1)(p<0.01),respectively,whereas the winter trends remained statistically insignificant throughout the study period.Leaf area index dynamics were identified as the primary driver of the increase in T/ET during summer,accounting for 79%of the trend.By contrast,climate change was the main contributor to the rising T/ET trends in spring and autumn,accounting for 72%and 77%of the T/ET increase,respectively.Additionally,warming is pivotal for climate-driven changes in T/ET trends.This study elucidated seasonal variations in T/ET responses to environmental factors,offering critical insights for the sustainable management of ecosystems and accurate prediction of future environmental change impacts.展开更多
In response to the rise of the energy storage industries such as new energy vehicles and the wide application of lithium in various fields worldwide,the global demand for lithium resources has been in explosive growth...In response to the rise of the energy storage industries such as new energy vehicles and the wide application of lithium in various fields worldwide,the global demand for lithium resources has been in explosive growth.In order to further comprehensively understand the global supply and demand pattern,development and utilization status,genesis of ore deposits and other characteristics of lithium resources,based on the achievements of many researchers at home and abroad,this paper systematically summarized the lithium supply and demand situation,resource endowment,deposit classification and distribution,typical geological characteristics,metallogenic factors and metallogenic regularity of terrestrial brine-type lithium deposits which are the main types of development and utilization all over the world.The review shows that brine-type lithium resource and(or)reserves in the plateau salt lakes are huge and play an important role.In addition,the mineralization potential of the underground brine-type lithium deposit is broad worldwide.The potential resources of underground brines are enormous,and the geothermal spring water type is also worthy of attention.Brine lithium deposits are mainly controlled by the subduction and collision of regional plate tectonics,arid climate and provenance conditions.Strengthening of the scientific research on underground brines in the future is expected to provide another significant support for the global demand for lithium resources.展开更多
The efficient integration of satellite and terrestrial networks has become an important component for 6 G wireless architectures to provide highly reliable and secure connectivity over a wide geographical area.As the ...The efficient integration of satellite and terrestrial networks has become an important component for 6 G wireless architectures to provide highly reliable and secure connectivity over a wide geographical area.As the satellite and cellular networks are developed separately these years,the integrated network should synergize the communication,storage,computation capabilities of both sides towards an intelligent system more than mere consideration of coexistence.This has motivated us to develop double-edge intelligent integrated satellite and terrestrial networks(DILIGENT).Leveraging the boost development of multi-access edge computing(MEC)technology and artificial intelligence(AI),the framework is entitled with the systematic learning and adaptive network management of satellite and cellular networks.In this article,we provide a brief review of the state-of-art contributions from the perspective of academic research and standardization.Then we present the overall design of the proposed DILIGENT architecture,where the advantages are discussed and summarized.Strategies of task offloading,content caching and distribution are presented.Numerical results show that the proposed network architecture outperforms the existing integrated networks.展开更多
Aerosols represent an important source of terrestrial organic carbon(OC)from the East Asian continent to the China marginal seas,thus their provenance and transport play important roles in the global carbon cycle.Fift...Aerosols represent an important source of terrestrial organic carbon(OC)from the East Asian continent to the China marginal seas,thus their provenance and transport play important roles in the global carbon cycle.Fifty samples of total suspended particle were collected seasonally from the nearshore Huaniao Island(HNI)in East China Sea(ECS)from April 2018 to January 2019;and they were analyzed for total organic carbon(TOC)content and stable carbon isotope(δ^(13)C),as well as terrestrial bio-markers including n-alkanes(C_(20)-C_(33)),n-alkanols(C_(20)-C32)and n-fatty acids(n-FAs,C_(20)-C30),to distinguish the seasonal variabili-ties of terrestrial OC sources and reveal the influence of the long-range air mass transport on these sources.The TOC-δ^(13)C values(range from−27.3‰to−24.3‰)and molecular distributions of terrestrial biomarkers both suggested that terrestrial OC contribu-tions to aerosols had significant seasonal variations.The source indices of terrestrial biomarkers(e.g.,Fossil%=82.8%for n-alkanes)revealed that the fossil fuel OC contributions,including coal burning and vehicular emission,were higher in winter,mainly because of the long-range air mass transport from the north of the East Asian continent.The terrestrial plant OC contributions were higher in summer(e.g.,Wax%=32.4%for n-alkanes),likely due to local vegetation sources from HNI and East Asian continental air masses.Cluster analysis of air mass backward-trajectories clearly showed that transport pathway plays an important role in determining the organic constituents of aerosols in China marginal seas.A comparison of these terrestrial OC contributions from different air mass origins suggested that fossil fuel OC showed less variations among various air mass origins from northern China in winter,while terrestrial plant OC sources from northern and southern China in summer contributed more than that from the air masses transported through the ECS.These results provided a basis for future quantification of terrestrial OC from different origins in marine aerosols,by combining biomarker index and carbon isotopes.展开更多
Soil stores a large amount of the terrestrial ecosystem carbon (C) and plays an important role in maintaining global C balance. However, very few studies have addressed the regional patterns of soil organic carbon (SO...Soil stores a large amount of the terrestrial ecosystem carbon (C) and plays an important role in maintaining global C balance. However, very few studies have addressed the regional patterns of soil organic carbon (SOC) storage and the main factors influencing its changes in Chinese terrestrial ecosystems, especially using field measured data. In this study, we collected information on SOC storage in main types of ecosystems (including forest, grassland, cropland, and wetland) across 18 regions in China during the 1980s (from the Second National Soil Survey of China, SNSSC) and the 2010s (from studies published between 2004 and 2014), and evaluated its changing trends during these 30 years. The SOC storage (0-100 cm) in Chinese terrestrial ecosystems was 83.46 ± 11.89 Pg C in the 1980s and 86.50 ± 8.71 Pg C in the 2010s, and the net increase over the 30 years was 3.04 ± 1.65 Pg C, with an overall rate of 0.101 ± 0.055 Pg C yr<sup>-1</sup>. This increase was mainly observed in the topsoil (0-20 cm). Forests, grasslands, and croplands SOC storage increased 2.52 ± 0.77, 0.40 ± 0.78, and 0.07 ± 0.31 Pg C, respectively, which can be attributed to the several ecological restoration projects and agricultural practices implemented. On the other hand, SOC storage in wetlands declined 0.76 ± 0.29 Pg C, most likely because of the decrease of wetland area and SOC density. Combining these results with those of vegetation C sink (0.100 Pg C yr<sup>-1</sup>), the net C sink in Chinese terrestrial ecosystems was about 0.201 ± 0.061 Pg C yr<sup>-1</sup>, which can offset 14.85%-27.79% of the fossil fuel C emissions from the 1980s to the 2010s. These first estimates of soil C sink based on field measured data supported the premise that China’s terrestrial ecosystems have a large C sequestration potential, and further emphasized the importance of forest protection and reforestation to increase SOC storage capacity.展开更多
Mobile communication standards have been developed into a new era of B5G and 6G.In recent years,low earth orbit(LEO)satellites and space Internet have become hot topics.The integrated satellite and terrestrial systems...Mobile communication standards have been developed into a new era of B5G and 6G.In recent years,low earth orbit(LEO)satellites and space Internet have become hot topics.The integrated satellite and terrestrial systems have been widely discussed by industries and academics,and even are expected to be applied in those huge constellations in construction.This paper points out the trends of two stages towards system integration of the terrestrial mobile communication and the satellite communications:to be compatible with 5G,and to be integrated within 6G.Based on analysis of the challenges of both stages,key technologies are thereafter analyzed in detail,covering both air interface currently discussed in 3GPP for B5G and also novel network architecture and related transmission technologies toward future 6G.展开更多
From 1992 to 2015, ecological environment has been threatened by the changes of cropland around the world. In order to evaluate the impact of cropland changes on ecosystem, we calculated the response of terrestrial ec...From 1992 to 2015, ecological environment has been threatened by the changes of cropland around the world. In order to evaluate the impact of cropland changes on ecosystem, we calculated the response of terrestrial ecosystem service values (TESVs) variation to cropland conversion based on land-use data from European Space Agency (ESA). The results showed that cropland changes were responsible for an absolute loss of $166.82 billion, equivalent to 1.17% of global TESVs in 1992. Among the different regions, the impact of cropland changes on TESVs was significant in South America and Africa but not obvious in Oceania, Asia and Europe. Cropland expansion from tropical forest was the main reason for decreases in TESVs globally, especially in South America, Africa and Asia. The effect of wetland converted to cropland was notable in North America and Europe while grassland converted to cropland played an important role in Oceania, Africa and Asia. In Europe, the force of urban expansion cannot be ignored as well. The conversion of cropland to tropical or temperate forest partly compensated for the loss of TESVs globally, especially in Asia.展开更多
In this paper, we use CEVSA, a process-based model, which has been validated on regional and global scales, to explore the temporal and spatial patterns of Net Primary Productivity (NPP) a...In this paper, we use CEVSA, a process-based model, which has been validated on regional and global scales, to explore the temporal and spatial patterns of Net Primary Productivity (NPP) and its responses to interannual climate fluctuations in China's terrestrial ecosystems over the period 1981-1998. The estimated results suggest that, in this study period, the averaged annual total NPP is about 3.09 Gt C/yr -1 and average NPP is about 342 g C/m 2 . The results also showed that the precipitation was the key factor determining the spatial distribution and temporal trends of NPP. Temporally, the total NPP exhibited a slowly increasing trend. In some ENSO years (e.g. 1982, 1986, 1997) NPP decreased clearly compared to the previous year, but the relationship between ENSO and NPP is complex due to the integrated effects of monsoons and regional differentiation. Spatially, the relatively high NPP occurred at the middle high latitudes, the low latitudes and the lower appeared at the middle latitudes. On national scale, precipitation is the key control factor on NPP variations and there exists a weak correlation between NPP and temperature, but regional responses are greatly different.展开更多
The fore leg of mole cricket （Orthoptera： Glyllotalpidae） has developed into claw for digging and excavating. As the result of having a well-suited body and appendages for living underground, mole cricket still nee...The fore leg of mole cricket （Orthoptera： Glyllotalpidae） has developed into claw for digging and excavating. As the result of having a well-suited body and appendages for living underground, mole cricket still needs to manoeuvre on land in some cases with some kinds of gait. In this paper, the three-dimensional kinematics information of mole cricket in terrestrial walking was recorded by using a high speed 3D video recording system. The mode and the gait of the terrestrial walking mole cricket were investigated by analyzing the kinematics parameters, and the kinematics coupling disciplines of each limb and body were discussed. The results show that the locomotion gait of mole cricket in terrestrial walking belongs to a distinctive alternating tripod gait. We also found that the fore legs of a mole cricket are not as effective as that of common hexapod insects, its middle legs and body joints act more effective in walking and turning which compensate the function of fore legs. The terrestrial lo-comotion of mole cricket is the result of biological coupling of three pairs of legs, the distinctive alternating tripod gait and the trunk locomotion.展开更多
Owing to the lack o f terrestrial heat flow data, studying lithospheric thermal structure and geodynamics of the Yingen-Ejinaqi Basin in Inner Mongolia is limited. In this paper, the terrestrial heat flow o f the Chag...Owing to the lack o f terrestrial heat flow data, studying lithospheric thermal structure and geodynamics of the Yingen-Ejinaqi Basin in Inner Mongolia is limited. In this paper, the terrestrial heat flow o f the Chagan sag in the YingenEjinaqi Basin were calculated by 193 system steady-state temperature measurements of 4 wells, and newly measuring 62 rock thermal conductivity and 20 heat production rate data on basis o f the original 107 rock thermal conductivity and 70 heat production data. The results show that the average thermal conductivity and heat production rate are 2.11 ±0.28 W/(m.K) and2.42±0.25 nW/m^3 in the Lower Cretaceous o f the Chagan sag. The average geothermal gradient from the Lower Suhongtu 2 Formation to the Suhongtu 1 Fonnation is 37.6 °C/km, and that o f the Bayingebi 2 Formation is 27.4 °C/km. Meanwhile, the average terrestrial heat flow in the Chagan sag is 70.6 mW/m^2. On the above results, it is clear that there is an obvious negative correlation between the thermal conductivity o f the stratum and its geothermal gradient. Moreover, it reveals that there is a geothermal state between tectonically stable and active areas. This work may provide geothermal parameters for further research o f lithospheric thermal structure and geodynamics in the Chagan sag.展开更多
Understanding the spatial variation in annual actual evapotranspiration （AET） and its influencing factors is crucial for a better understanding of hydrological processes and water resources management. By synthesizi...Understanding the spatial variation in annual actual evapotranspiration （AET） and its influencing factors is crucial for a better understanding of hydrological processes and water resources management. By synthesizing ecosystem-level observations of eddy-covariance flux sites in China （a total of 61 sites）, we constructed the most complete AET dataset in China up to now. Based on this dataset, we quantified the statistic characteristics of AET and water budgets （defined as the ratio of AET to annual mean precipitation （MAP）, AET/MAP） of terrestrial ecosystems in China. Results showed that AET differed significantly among both different vegetation types and climate types in China, with overall mean AET of 534.7＋232.8 mm yr1. AET/MAP also differed significantly among different climate types, but there were no distinct differences in AET/MAP values across vegetation types, with mean AET/MAP of 0.82＋0.28 for non-irrigated ecosystems. We further investigated how the main climatic factors and vegetation attributes control the spatial variation in AET. Our findings revealed that the spatial variation of AET in China was closely correlated with the geographical patterns of climate and vegetation, in which the effects of total annual net radiation （Ro）, MAP and mean annual air temperature （MAT） were dominant. Thus, we proposed an empirical equation to describe the spatial patterns of AET in China, which could explain about 84% of the spatial variation in AET of terrestrial ecosystems in China. Based on the constructed dataset, we also evaluated the uncertainties of five published global evapotranspiration products in simulating site-specific AET in China. Results showed that large biases in site-specific AET values existed for all five global evapotranspiration products, which indicated that it is necessary to involve more observation data of China in their parameterization or validation, while our AET dataset would provide a data source for it.展开更多
文摘With the large-scale deployment of satellite constellations such as Starlink and the rapid advancement of technologies including artificial intelligence (AI) and non-terrestrial networks (NTNs), the integration of high, medium, and low Earth orbit satellite networks with terrestrial networks has become a critical direction for future communication technologies. The objective is to develop a space-terrestrial integrated 6G network that ensures ubiquitous connectivity and seamless services, facilitating intelligent interconnection and collaborative symbiosis among humans, machines, and objects. This integration has become a central focus of global technological innovation.
基金funded by the Postdoctoral Research Startup Foundation of University of Jinan(Grant No.100389917).
文摘Climate change and anthropogenic activities have driven significant terrestrial water storage changes(TWSC)in the Three Rivers Source Region(TRSR),exerting profound impacts on freshwater availability across China and broader Asia.However,long-term TWSC characterization remains challenging due to limited observational data in this alpine region.Here,we integrate GRACE observations(2002-2020),ERA5-Land reanalysis,and GLDAS data to reconstruct TWSC using two methods:(1)the water balance method(PER)and(2)the component summation method(SS),applied to three input datasets(ERA5-Land,GLDAS,and their average,GLER).Comparative analysis reveals that the SS method applied to GL-ER yields the highest consistency with GRACE-derived TWSC.Using this optimal approach,we extend the analysis to 1951~2020,uncovering spatiotemporal TWSC patterns.Although annual TWSC trends appear negligible due to strong seasonality,we introduce the intra-year TWSC fluctuation(TWSCF)index to quantify cumulative variability.A significant(p<0.05)transition occurred in 1980,with TWSCF shifting from a declining trend(-0.39 mm/yr)to an increasing trend(0.56 mm/yr),primarily driven by soil moisture changes.However,Hurst exponent analysis suggests this upward trend may not persist.Drought and vegetation assessments indicate concurrent wetting and greening in the TRSR.TWSC correlates strongly with meteorological drought,acting as a reliable drought indicator while its linkage with vegetation dynamics suggests a potential contribution to greening.Our findings provide a robust framework for understanding long-term TWSC evolution and its hydrological-ecological interactions under climate change.
基金supported by the Chinese Scholarship Council under Grant 202106910006.
文摘Branch angles are an important plant morphological trait affecting light interception within forest canopies.However,studies on branch angles have been limited due to the time-consuming nature of manual measurements using a protractor.Terrestrial laser scanning(TLS),however,provides new opportunities to measure branch angles more efficiently.Despite this potential,studies validating branch angle measurements from TLS have been limited.Here,our aim is to evaluate both manual and automatic branch angle measurements of European beech from TLS data using traditional field-measurements with a protractor as a reference.We evaluated the accuracy of branch angle measurements based on four automated algorithms(aRchiQSM,TreeQSM,Laplacian,SemanticLaplacian)from TLS data.Additionally,we assessed different ways of manual branch angle measurements in the field.Our study was based on a dataset comprising 124 branch angles measured from six European beech in a European deciduous forest.Our results show that manual branch angle measurements from TLS data are in high agreement with the reference(root-mean-squared error,RMSE:[3.57°-4.18°],concordance correlation coefficient,CCC:[0.950.97])across different branch length positions.Automated algorithms also are in high agreement with the reference although RMSE is approximately twice as large compared to manual branch angle measurements from TLS(RMSE:[9.29°-10.55°],CCC:[0.830.86])with manual leaf points removal.When applying the automatic wood-leaf separation algorithm,the performance of the four methods declined significantly,with only approximately 20 branch angles successfully identified.Moreover,it is important to note that there is no influence of the measurement position(branch surface versus center)for branch angle measurements.However,for curved branches,the selection of branch measurement length significantly impacts the branch angle measurement.This study provides a comprehensive understanding of branch angle measurements in forests.We show that automated measurement methods based on TLS data of branch angles are a valuable tool to quantify branch angles at larger scales.
基金co-supported by the National Natural Science Foundation of China(Nos.62225103,U2441227,U24A20211)the Fundamental Research Funds for the Central Universities of China(No.FRF-TP-22-002C2)。
文摘1.Introduction As a key development of the next-generation spatial information infrastructure,1the Satellite-Terrestrial Integrated Network(STIN)has become a strategic priority actively pursued by major spacefaring nations and regions,including the United States,Europe,China,and Russia.Specifically,Space X’s Starlink project has deployed over 6750 satellites,2while One Web has completed its initial phase of satellite constellation deployment with more than 600 satellites.
基金the funding of the National Natural Science Foundation of China(Nos.42222209,42303056)。
文摘The rhenium-osmium(Re-Os)isotope system is a powerful tool for dating organic-rich sedimentary rocks,yet the mechanisms of Re and Os uptake and their fractionation in different types of organic matter remain poorly understood.Here,we investigate the role of terrestrial organic matter(e.g.,wood of the species Taxodium distichum and charcoal generated from the same species in the laboratory)in Re and Os enrichment and isotope fractionation through laboratory experiments.The results show that charcoal has a significantly higher capacity to uptake both Re(68-77 times greater)and Os(1.7-2.2 times higher)compared to wood,with charcoal preferentially accumulating Re over Os,leading to higher^(187)Re/^(188)Os ratios.These findings highlight the important contribution of terrestrial organic matter,particularly charcoal,to Re and Os concentrations and isotope fractionation in shales,and the importance of organic matter type for chelating Re and Os as previously discussed.Furthermore,we discuss the potential of using Re to track organic carbon weathering,noting that the coupled release of Re and organic carbon during weathering provides new insights into carbon cycling processes.
基金Earthquake Science and Technology Program of Hebei Province under Grant Nos.DZ2021120300001,DZ2024083000001,DZ2024112400016 and DZ2025092800001。
文摘In this study,terrestrial laser scanning(TLS)is used to collect building data after the M_(s) 7.0 magnitude earthquake in Lushan,Sichuan,China in 2013 for analysis and research.The analysis focuses on extracting the tilt and deformation of masonry buildings that are difficult to identify through visual inspection in basically intact,slightly damaged and moderately damaged masonry buildings,to solve the problem of ambiguous identification of damage.A quantitative analysis of the determination indexes of the degree of earthquake damage was carried out,and the numerical characteristics parameters such as the curvature of the wall point cloud proximity,angle,contour of the fitted plane of the point cloud,verticality(flatness)of the wall,standard deviation of the profile and angle of the profile were established to determine the degree of earthquake damage to buildings based on LiDAR data.The development of quantitative determination indexes for the degree of earthquake damage of buildings in this study has important application value for LiDAR data in the identification and extraction of earthquake damage information and damage level determination.
基金funded by State Key Laboratory of Micro-Spacecraft Rapid Design and Intelligent Cluster under Grant MS01240103the National Natural Science Foundation of China under Grant 62071146National 2011 Collaborative Innovation Center of Wireless Communication Technologies under Grant 2242022k60006.
文摘In this paper,we propose a joint power and frequency allocation algorithm considering interference protection in the integrated satellite and terrestrial network(ISTN).We efficiently utilize spectrum resources by allowing user equipment(UE)of terrestrial networks to share frequencies with satellite networks.In order to protect the satellite terminal(ST),the base station(BS)needs to control the transmit power and frequency resources of the UE.The optimization problem involves maximizing the achievable throughput while satisfying the interference protection constraints of the ST and the quality of service(QoS)of the UE.However,this problem is highly nonconvex,and we decompose it into power allocation and frequency resource scheduling subproblems.In the power allocation subproblem,we propose a power allocation algorithm based on interference probability(PAIP)to address channel uncertainty.We obtain the suboptimal power allocation solution through iterative optimization.In the frequency resource scheduling subproblem,we develop a heuristic algorithm to handle the non-convexity of the problem.The simulation results show that the combination of power allocation and frequency resource scheduling algorithms can improve spectrum utilization.
基金supported by the National Natural Science Foundation of China(Nos.41907325 and 41571470).
文摘The present study was conducted to examine the trophic transfer of potentially toxic elements(PTEs)in a closed arsenic mine.Eight PTEs in a soil-plant-leaf litter-earthworm-top predators(free-range local chicken and wild passerine bird)system were analyzed for nitrogen and carbon stable isotopes,PTE concentrations,bioaccumulation factors(BAFs),and transfer factors(TFs).The PTE concentrations in soils from mining areas were generally higher than a adjacent controlled area,with As and Cd in soils showing the prominent compared to other six PTEs,as seen for the indices of geo-accumulation index(I_(geo)),pollution index(PI)and potential ecological risk index(RI).The relatively high BAF and TF values suggested a distinct biotransfer of PTEs along the soil-plant-leaf litter-earthworm system.BAFs were mostly<1 except in earthworms,indicating that earthworms had a strong capacity to take up these metals.The TFs varied both among PTEs and organism’s species,e.g.,the transfer capacities of As in Pteris vittata and Pteris cretica,Cd in Miscanthus sinensis,and Pb,Cr and Mn in moss were the highest.For local free-range chicken and wild passerine bird,the concentrations of PTEs were higher in gastric contents and feather than in internal tissue(stomach,liver and heart),with lower contents in muscle and egg.Bioaccumulation of PTEs generally decreased from decomposer earthworms,to primary producer plants,to top predator,indicating a potential bio-dilution tendency in higher trophic levels in the terrestrial food chain.
文摘With the advent of the digital era,the field of communications is undergoing profound transformation.Among the most groundbreaking developments is the emergence of non-terrestrial networks(NTN),which represent not only a technological leap forward but also a major trend shaping the future of global connectivity.As a layered heterogeneous network,NTN integrates multiple aerial platforms—including satellites,high-altitude platform systems(HAPS),and unmanned aerial systems(UAS)—to provide flexible and composable solutions aimed at achieving seamless worldwide communication coverage.
基金National Natural Science Foundation of China,No.42201312,No.42301538Natural Science Foundation of Shandong Province,No.ZR2022QD118。
文摘The transpiration-to-evapotranspiration ratio(T/ET)is a crucial indicator of the carbon-water cycle and energy balance.Despite the marked seasonality of warming and greening patterns,the differential responses of T/ET to environmental changes across the seasons remain unclear.To address this,we employed a model-data fusion method,integrating the Priestley–Taylor Jet Propulsion Lab model with observational datasets,to analyze the seasonal trends of T/ET in China’s terrestrial ecosystems from 1981 to 2021.The results showed that T/ET significantly increased in spring,summer,and autumn,with growth rates of 0.0018 a^(–1)(p<0.01),0.0024 a^(–1)(p<0.01),and 0.0013 a^(–1)(p<0.01),respectively,whereas the winter trends remained statistically insignificant throughout the study period.Leaf area index dynamics were identified as the primary driver of the increase in T/ET during summer,accounting for 79%of the trend.By contrast,climate change was the main contributor to the rising T/ET trends in spring and autumn,accounting for 72%and 77%of the T/ET increase,respectively.Additionally,warming is pivotal for climate-driven changes in T/ET trends.This study elucidated seasonal variations in T/ET responses to environmental factors,offering critical insights for the sustainable management of ecosystems and accurate prediction of future environmental change impacts.
基金This study was jointly supported by Central Welfare Basic Scientific Research Business Expenses(KK2005,YYWF201607)the project of the industrial leading talant of Wuhan municipality of Hubei Province,the Editor of China Geology,Rui-qin Li,and many thanks for a nice review by anonymous reviewers.
文摘In response to the rise of the energy storage industries such as new energy vehicles and the wide application of lithium in various fields worldwide,the global demand for lithium resources has been in explosive growth.In order to further comprehensively understand the global supply and demand pattern,development and utilization status,genesis of ore deposits and other characteristics of lithium resources,based on the achievements of many researchers at home and abroad,this paper systematically summarized the lithium supply and demand situation,resource endowment,deposit classification and distribution,typical geological characteristics,metallogenic factors and metallogenic regularity of terrestrial brine-type lithium deposits which are the main types of development and utilization all over the world.The review shows that brine-type lithium resource and(or)reserves in the plateau salt lakes are huge and play an important role.In addition,the mineralization potential of the underground brine-type lithium deposit is broad worldwide.The potential resources of underground brines are enormous,and the geothermal spring water type is also worthy of attention.Brine lithium deposits are mainly controlled by the subduction and collision of regional plate tectonics,arid climate and provenance conditions.Strengthening of the scientific research on underground brines in the future is expected to provide another significant support for the global demand for lithium resources.
基金supportedin part by the National Science Foundation of China(NSFC)under Grant 61631005,Grant 61771065,Grant 61901048in part by the Zhijiang Laboratory Open Project Fund 2020LCOAB01in part by the Beijing Municipal Science and Technology Commission Research under Project Z181100003218015。
文摘The efficient integration of satellite and terrestrial networks has become an important component for 6 G wireless architectures to provide highly reliable and secure connectivity over a wide geographical area.As the satellite and cellular networks are developed separately these years,the integrated network should synergize the communication,storage,computation capabilities of both sides towards an intelligent system more than mere consideration of coexistence.This has motivated us to develop double-edge intelligent integrated satellite and terrestrial networks(DILIGENT).Leveraging the boost development of multi-access edge computing(MEC)technology and artificial intelligence(AI),the framework is entitled with the systematic learning and adaptive network management of satellite and cellular networks.In this article,we provide a brief review of the state-of-art contributions from the perspective of academic research and standardization.Then we present the overall design of the proposed DILIGENT architecture,where the advantages are discussed and summarized.Strategies of task offloading,content caching and distribution are presented.Numerical results show that the proposed network architecture outperforms the existing integrated networks.
基金This study was supported by the National Natural Science Foundation of China(No.U1706219).This is MCTL(Key Laboratory of Marine Chemistry Theory and Technology)contribution#237.
文摘Aerosols represent an important source of terrestrial organic carbon(OC)from the East Asian continent to the China marginal seas,thus their provenance and transport play important roles in the global carbon cycle.Fifty samples of total suspended particle were collected seasonally from the nearshore Huaniao Island(HNI)in East China Sea(ECS)from April 2018 to January 2019;and they were analyzed for total organic carbon(TOC)content and stable carbon isotope(δ^(13)C),as well as terrestrial bio-markers including n-alkanes(C_(20)-C_(33)),n-alkanols(C_(20)-C32)and n-fatty acids(n-FAs,C_(20)-C30),to distinguish the seasonal variabili-ties of terrestrial OC sources and reveal the influence of the long-range air mass transport on these sources.The TOC-δ^(13)C values(range from−27.3‰to−24.3‰)and molecular distributions of terrestrial biomarkers both suggested that terrestrial OC contribu-tions to aerosols had significant seasonal variations.The source indices of terrestrial biomarkers(e.g.,Fossil%=82.8%for n-alkanes)revealed that the fossil fuel OC contributions,including coal burning and vehicular emission,were higher in winter,mainly because of the long-range air mass transport from the north of the East Asian continent.The terrestrial plant OC contributions were higher in summer(e.g.,Wax%=32.4%for n-alkanes),likely due to local vegetation sources from HNI and East Asian continental air masses.Cluster analysis of air mass backward-trajectories clearly showed that transport pathway plays an important role in determining the organic constituents of aerosols in China marginal seas.A comparison of these terrestrial OC contributions from different air mass origins suggested that fossil fuel OC showed less variations among various air mass origins from northern China in winter,while terrestrial plant OC sources from northern and southern China in summer contributed more than that from the air masses transported through the ECS.These results provided a basis for future quantification of terrestrial OC from different origins in marine aerosols,by combining biomarker index and carbon isotopes.
基金The Chinese Academy of Sciences Strategic Priority Research Program,No.XDA19020302National Key Research Project of China,No.2016YFC0500202National Natural Science Foundation of China,No.31290221,No.41571130043,No.31570471
文摘Soil stores a large amount of the terrestrial ecosystem carbon (C) and plays an important role in maintaining global C balance. However, very few studies have addressed the regional patterns of soil organic carbon (SOC) storage and the main factors influencing its changes in Chinese terrestrial ecosystems, especially using field measured data. In this study, we collected information on SOC storage in main types of ecosystems (including forest, grassland, cropland, and wetland) across 18 regions in China during the 1980s (from the Second National Soil Survey of China, SNSSC) and the 2010s (from studies published between 2004 and 2014), and evaluated its changing trends during these 30 years. The SOC storage (0-100 cm) in Chinese terrestrial ecosystems was 83.46 ± 11.89 Pg C in the 1980s and 86.50 ± 8.71 Pg C in the 2010s, and the net increase over the 30 years was 3.04 ± 1.65 Pg C, with an overall rate of 0.101 ± 0.055 Pg C yr<sup>-1</sup>. This increase was mainly observed in the topsoil (0-20 cm). Forests, grasslands, and croplands SOC storage increased 2.52 ± 0.77, 0.40 ± 0.78, and 0.07 ± 0.31 Pg C, respectively, which can be attributed to the several ecological restoration projects and agricultural practices implemented. On the other hand, SOC storage in wetlands declined 0.76 ± 0.29 Pg C, most likely because of the decrease of wetland area and SOC density. Combining these results with those of vegetation C sink (0.100 Pg C yr<sup>-1</sup>), the net C sink in Chinese terrestrial ecosystems was about 0.201 ± 0.061 Pg C yr<sup>-1</sup>, which can offset 14.85%-27.79% of the fossil fuel C emissions from the 1980s to the 2010s. These first estimates of soil C sink based on field measured data supported the premise that China’s terrestrial ecosystems have a large C sequestration potential, and further emphasized the importance of forest protection and reforestation to increase SOC storage capacity.
基金This work was supported in part by the National Science Fund for Distinguished Young Scholars in China under grant 61425012the National Science Foundation Project in China under grant 61931005 and 61731017.
文摘Mobile communication standards have been developed into a new era of B5G and 6G.In recent years,low earth orbit(LEO)satellites and space Internet have become hot topics.The integrated satellite and terrestrial systems have been widely discussed by industries and academics,and even are expected to be applied in those huge constellations in construction.This paper points out the trends of two stages towards system integration of the terrestrial mobile communication and the satellite communications:to be compatible with 5G,and to be integrated within 6G.Based on analysis of the challenges of both stages,key technologies are thereafter analyzed in detail,covering both air interface currently discussed in 3GPP for B5G and also novel network architecture and related transmission technologies toward future 6G.
基金National Natural Science Foundation of China,No.41771116,No.41501095National Basic Research Program of China,No.2015CB452705National Key Research and Development Program of China,No.2016YFC0502103
文摘From 1992 to 2015, ecological environment has been threatened by the changes of cropland around the world. In order to evaluate the impact of cropland changes on ecosystem, we calculated the response of terrestrial ecosystem service values (TESVs) variation to cropland conversion based on land-use data from European Space Agency (ESA). The results showed that cropland changes were responsible for an absolute loss of $166.82 billion, equivalent to 1.17% of global TESVs in 1992. Among the different regions, the impact of cropland changes on TESVs was significant in South America and Africa but not obvious in Oceania, Asia and Europe. Cropland expansion from tropical forest was the main reason for decreases in TESVs globally, especially in South America, Africa and Asia. The effect of wetland converted to cropland was notable in North America and Europe while grassland converted to cropland played an important role in Oceania, Africa and Asia. In Europe, the force of urban expansion cannot be ignored as well. The conversion of cropland to tropical or temperate forest partly compensated for the loss of TESVs globally, especially in Asia.
基金Knowledge Innovation Project of IGSNRR CAS No.CXIOG-E01-02-04
文摘In this paper, we use CEVSA, a process-based model, which has been validated on regional and global scales, to explore the temporal and spatial patterns of Net Primary Productivity (NPP) and its responses to interannual climate fluctuations in China's terrestrial ecosystems over the period 1981-1998. The estimated results suggest that, in this study period, the averaged annual total NPP is about 3.09 Gt C/yr -1 and average NPP is about 342 g C/m 2 . The results also showed that the precipitation was the key factor determining the spatial distribution and temporal trends of NPP. Temporally, the total NPP exhibited a slowly increasing trend. In some ENSO years (e.g. 1982, 1986, 1997) NPP decreased clearly compared to the previous year, but the relationship between ENSO and NPP is complex due to the integrated effects of monsoons and regional differentiation. Spatially, the relatively high NPP occurred at the middle high latitudes, the low latitudes and the lower appeared at the middle latitudes. On national scale, precipitation is the key control factor on NPP variations and there exists a weak correlation between NPP and temperature, but regional responses are greatly different.
基金Acknowledgement This work was supported by the National Natural Science Foundation （Grant No. 50635030）.
文摘The fore leg of mole cricket （Orthoptera： Glyllotalpidae） has developed into claw for digging and excavating. As the result of having a well-suited body and appendages for living underground, mole cricket still needs to manoeuvre on land in some cases with some kinds of gait. In this paper, the three-dimensional kinematics information of mole cricket in terrestrial walking was recorded by using a high speed 3D video recording system. The mode and the gait of the terrestrial walking mole cricket were investigated by analyzing the kinematics parameters, and the kinematics coupling disciplines of each limb and body were discussed. The results show that the locomotion gait of mole cricket in terrestrial walking belongs to a distinctive alternating tripod gait. We also found that the fore legs of a mole cricket are not as effective as that of common hexapod insects, its middle legs and body joints act more effective in walking and turning which compensate the function of fore legs. The terrestrial lo-comotion of mole cricket is the result of biological coupling of three pairs of legs, the distinctive alternating tripod gait and the trunk locomotion.
基金funded by the National Natural Science Foundation of China (grant no. 41374089, 41402219)the Foundation of the Geoscience Young Science Foundation of Liu Baojun (Grant No. DMSM2017003)+1 种基金the Sichuan Science & Technology Foundation (Grant No. 2016JQ0043)the State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing (Grant No. PRP/open-1705)
文摘Owing to the lack o f terrestrial heat flow data, studying lithospheric thermal structure and geodynamics of the Yingen-Ejinaqi Basin in Inner Mongolia is limited. In this paper, the terrestrial heat flow o f the Chagan sag in the YingenEjinaqi Basin were calculated by 193 system steady-state temperature measurements of 4 wells, and newly measuring 62 rock thermal conductivity and 20 heat production rate data on basis o f the original 107 rock thermal conductivity and 70 heat production data. The results show that the average thermal conductivity and heat production rate are 2.11 ±0.28 W/(m.K) and2.42±0.25 nW/m^3 in the Lower Cretaceous o f the Chagan sag. The average geothermal gradient from the Lower Suhongtu 2 Formation to the Suhongtu 1 Fonnation is 37.6 °C/km, and that o f the Bayingebi 2 Formation is 27.4 °C/km. Meanwhile, the average terrestrial heat flow in the Chagan sag is 70.6 mW/m^2. On the above results, it is clear that there is an obvious negative correlation between the thermal conductivity o f the stratum and its geothermal gradient. Moreover, it reveals that there is a geothermal state between tectonically stable and active areas. This work may provide geothermal parameters for further research o f lithospheric thermal structure and geodynamics in the Chagan sag.
基金National Natural Science Foundation of China,No.31290221,No.31420103917
文摘Understanding the spatial variation in annual actual evapotranspiration （AET） and its influencing factors is crucial for a better understanding of hydrological processes and water resources management. By synthesizing ecosystem-level observations of eddy-covariance flux sites in China （a total of 61 sites）, we constructed the most complete AET dataset in China up to now. Based on this dataset, we quantified the statistic characteristics of AET and water budgets （defined as the ratio of AET to annual mean precipitation （MAP）, AET/MAP） of terrestrial ecosystems in China. Results showed that AET differed significantly among both different vegetation types and climate types in China, with overall mean AET of 534.7＋232.8 mm yr1. AET/MAP also differed significantly among different climate types, but there were no distinct differences in AET/MAP values across vegetation types, with mean AET/MAP of 0.82＋0.28 for non-irrigated ecosystems. We further investigated how the main climatic factors and vegetation attributes control the spatial variation in AET. Our findings revealed that the spatial variation of AET in China was closely correlated with the geographical patterns of climate and vegetation, in which the effects of total annual net radiation （Ro）, MAP and mean annual air temperature （MAT） were dominant. Thus, we proposed an empirical equation to describe the spatial patterns of AET in China, which could explain about 84% of the spatial variation in AET of terrestrial ecosystems in China. Based on the constructed dataset, we also evaluated the uncertainties of five published global evapotranspiration products in simulating site-specific AET in China. Results showed that large biases in site-specific AET values existed for all five global evapotranspiration products, which indicated that it is necessary to involve more observation data of China in their parameterization or validation, while our AET dataset would provide a data source for it.
