Antarctic clouds and their vertical structures play a significant role in influencing the regional radiation budget and ice mass balance;however,substantial uncertainties persist.Continuous monitoring and research are...Antarctic clouds and their vertical structures play a significant role in influencing the regional radiation budget and ice mass balance;however,substantial uncertainties persist.Continuous monitoring and research are essential for enhancing our understanding of these clouds.This study presents an analysis of cloud occurrence frequency and cloud-base heights(CBHs)at Zhongshan Station in East Antarctica for the first time,utilizing data from a C12 ceilometer covering the period from January 2022 to December 2023.The findings indicate that low clouds dominate at Zhongshan Station,with an average cloud occurrence frequency of 75%.Both the cloud occurrence frequency and CBH distribution exhibit distinct seasonal variations.Specifically,the cloud occurrence frequency during winter is higher than that observed in summer,while winter clouds can develop to greater heights.Over the Southern Ocean,the cloud occurrence frequency during summer surpasses that at Zhongshan Station,with clouds featuring lower CBHs and larger extinction coefficients.Furthermore,it is noteworthy that CBHs derived from the ceilometer are basically consistent with those obtained from radiosondes.Importantly,ERA5 demonstrates commendable performance in retrieving CBHs at Zhongshan Station when compared with ceilometer measurements.展开更多
Clouds are critical to the global radiation budget and hydrological cycle, but knowledge is still poor concerning the observed climatology of cloud-base height （CBH） in China. Based on fine-resolution sounding obser...Clouds are critical to the global radiation budget and hydrological cycle, but knowledge is still poor concerning the observed climatology of cloud-base height （CBH） in China. Based on fine-resolution sounding observations from the China Radiosonde Network （CRN）, the method used to estimate CBH was modified, and uncertainty analyses indicated that the CBH is good enough. The accuracy of CBH estimation is verified by the comparison between the sounding-derived CBHs and those estimated from the micro-pulse lidar and millimeter-wave cloud radar. As such, the CBH climatology was compiled for the period 2006-16. Overall, the CBH exhibits large geographic variability across China, at both 0800 Local Standard Time （LST） and 2000 LST, irrespective of season. In addition, the summertime cloud base tends to be elevated to higher altitudes in dry regions [i.e., Inner Mongolia and the North China Plain （NCP）]. By comparison, the Tibetan Plateau （TP）, Pearl River Delta （PRD） and Sichuan Basin （SCB） have relatively low CBHs （〈 2.4 km above ground level）. In terms of seasonality, the CBH reaches its maximum in summer and minimum in winter. A low cloud base tends to occur frequently （〉 70%） over the TP, PRD and SCB. In contrast, at most sites over the Yangtze River Delta （YRD） and the NCP, about half the cloud belongs to the high-cloud category. The CBH does not exhibit marked diurnal variation in summer, throughout all CRN sites, probably due to the persistent cloud coverage caused by the East Asia Summer Monsson. To the best of our knowledge, this is the first CBH climatology produced from sounding measurements in China, and provides a useful reference for obtaining observational cloud base information.展开更多
The satellite-based quantification of cloud radiative forcing remains poorly understood,due largely to the limitation or uncertainties in characterizing cloud-base height(CBH).Here,we use the CBH data from radiosonde ...The satellite-based quantification of cloud radiative forcing remains poorly understood,due largely to the limitation or uncertainties in characterizing cloud-base height(CBH).Here,we use the CBH data from radiosonde measurements over China in combination with the collocated cloud-top height(CTH) and cloud properties from MODIS/Aqua to quantify the impact of CBH on shortwave cloud radiative forcing(SWCRF).The climatological mean SWCRF at the surface(SWCRFSUR),at the top of the atmosphere(SWCRFTOA),and in the atmosphere(SWCRFATM) are estimated to be-97.14,-84.35,and 12.79 W m^(-2),respectively for the summers spanning 2010 to 2018 over China.To illustrate the role of the cloud base,we assume four scenarios according to vertical profile patterns of cloud optical depth(COD).Using the CTH and cloud properties from MODIS alone results in large uncertainties for the estimation of SWCRFATM,compared with those under scenarios that consider the CBH.Furthermore,the biases of the CERES estimation of SWCRFATM tend to increase in the presence of thick clouds with low CBH.Additionally,the discrepancy of SWCRFATM relative to that calculated without consideration of CBH varies according to the vertical profile of COD.When a uniform COD vertical profile is assumed,the largest SWCRF discrepancies occur during the early morning or late afternoon.By comparison,the two-point COD vertical distribution assumption has the largest uncertainties occurring at noon when the solar irradiation peaks.These findings justify the urgent need to consider the cloud vertical structures when calculating the SWCRF which is otherwise neglected.展开更多
In order to improve the efficiency of cloud-based web services,an improved plant growth simulation algorithm scheduling model.This model first used mathematical methods to describe the relationships between cloud-base...In order to improve the efficiency of cloud-based web services,an improved plant growth simulation algorithm scheduling model.This model first used mathematical methods to describe the relationships between cloud-based web services and the constraints of system resources.Then,a light-induced plant growth simulation algorithm was established.The performance of the algorithm was compared through several plant types,and the best plant model was selected as the setting for the system.Experimental results show that when the number of test cloud-based web services reaches 2048,the model being 2.14 times faster than PSO,2.8 times faster than the ant colony algorithm,2.9 times faster than the bee colony algorithm,and a remarkable 8.38 times faster than the genetic algorithm.展开更多
The integration of 5G technology with cloud-based control systems in industrial robots holds significant promise for the future of industrial automation.With its ultra-low latency,high data transfer speeds,and massive...The integration of 5G technology with cloud-based control systems in industrial robots holds significant promise for the future of industrial automation.With its ultra-low latency,high data transfer speeds,and massive connectivity,5G is poised to revolutionize real-time communication and coordination in manufacturing environments.This paper explores the prospects and challenges of applying 5G technology in industrial robots,focusing on cloud-based control systems that enable scalable,flexible,and efficient operations.Key advantages of 5G,including improved communication speed,enhanced real-time control,scalability,and predictive maintenance capabilities,are discussed.However,the transition to 5G also presents challenges,such as network reliability,security concerns,integration with legacy systems,and high implementation costs.The paper also examines case studies in the automotive,electronics,and aerospace industries,providing real-world examples of 5G adoption in industrial automation.The conclusion highlights key insights and outlines potential research directions for overcoming existing barriers and fully realizing the potential of 5G technology in industrial robot control.展开更多
The concept of sharing of personal health data over cloud storage in a healthcare-cyber physical system has become popular in recent times as it improves access quality.The privacy of health data can only be preserved...The concept of sharing of personal health data over cloud storage in a healthcare-cyber physical system has become popular in recent times as it improves access quality.The privacy of health data can only be preserved by keeping it in an encrypted form,but it affects usability and flexibility in terms of effective search.Attribute-based searchable encryption(ABSE)has proven its worth by providing fine-grained searching capabilities in the shared cloud storage.However,it is not practical to apply this scheme to the devices with limited resources and storage capacity because a typical ABSE involves serious computations.In a healthcare cloud-based cyber-physical system(CCPS),the data is often collected by resource-constraint devices;therefore,here also,we cannot directly apply ABSE schemes.In the proposed work,the inherent computational cost of the ABSE scheme is managed by executing the computationally intensive tasks of a typical ABSE scheme on the blockchain network.Thus,it makes the proposed scheme suitable for online storage and retrieval of personal health data in a typical CCPS.With the assistance of blockchain technology,the proposed scheme offers two main benefits.First,it is free from a trusted authority,which makes it genuinely decentralized and free from a single point of failure.Second,it is computationally efficient because the computational load is now distributed among the consensus nodes in the blockchain network.Specifically,the task of initializing the system,which is considered the most computationally intensive,and the task of partial search token generation,which is considered as the most frequent operation,is now the responsibility of the consensus nodes.This eliminates the need of the trusted authority and reduces the burden of data users,respectively.Further,in comparison to existing decentralized fine-grained searchable encryption schemes,the proposed scheme has achieved a significant reduction in storage and computational cost for the secret key associated with users.It has been verified both theoretically and practically in the performance analysis section.展开更多
This paper presents a cloud-based data-driven design optimization system,named DADOS,to help engineers and researchers improve a design or product easily and efficiently.DADOS has nearly 30 key algorithms,including th...This paper presents a cloud-based data-driven design optimization system,named DADOS,to help engineers and researchers improve a design or product easily and efficiently.DADOS has nearly 30 key algorithms,including the design of experiments,surrogate models,model validation and selection,prediction,optimization,and sensitivity analysis.Moreover,it also includes an exclusive ensemble surrogate modeling technique,the extended hybrid adaptive function,which can make use of the advantages of each surrogate and eliminate the effort of selecting the appropriate individual surrogate.To improve ease of use,DADOS provides a user-friendly graphical user interface and employed flow-based programming so that users can conduct design optimization just by dragging,dropping,and connecting algorithm blocks into a workflow instead of writing massive code.In addition,DADOS allows users to visualize the results to gain more insights into the design problems,allows multi-person collaborating on a project at the same time,and supports multi-disciplinary optimization.This paper also details the architecture and the user interface of DADOS.Two examples were employed to demonstrate how to use DADOS to conduct data-driven design optimization.Since DADOS is a cloud-based system,anyone can access DADOS at www.dados.com.cn using their web browser without the need for installation or powerful hardware.展开更多
With the rapid development of computer technology, cloud-based services have become a hot topic. They not only provide users with convenience, but also bring many security issues, such as data sharing and privacy issu...With the rapid development of computer technology, cloud-based services have become a hot topic. They not only provide users with convenience, but also bring many security issues, such as data sharing and privacy issue. In this paper, we present an access control system with privilege separation based on privacy protection(PS-ACS). In the PS-ACS scheme, we divide users into private domain(PRD) and public domain(PUD) logically. In PRD, to achieve read access permission and write access permission, we adopt the Key-Aggregate Encryption(KAE) and the Improved Attribute-based Signature(IABS) respectively. In PUD, we construct a new multi-authority ciphertext policy attribute-based encryption(CP-ABE) scheme with efficient decryption to avoid the issues of single point of failure and complicated key distribution, and design an efficient attribute revocation method for it. The analysis and simulation result show that our scheme is feasible and superior to protect users' privacy in cloud-based services.展开更多
Cloud-based satellite and terrestrial spectrum shared networks(CB-STSSN)combines the triple advantages of efficient and flexible net-work management of heterogeneous cloud access(H-CRAN),vast coverage of satellite net...Cloud-based satellite and terrestrial spectrum shared networks(CB-STSSN)combines the triple advantages of efficient and flexible net-work management of heterogeneous cloud access(H-CRAN),vast coverage of satellite networks,and good communication quality of terrestrial networks.Thanks to the complementary coverage characteristics,any-time and anywhere high-speed communications can be achieved to meet the various needs of users.The scarcity of spectrum resources is a common prob-lem in both satellite and terrestrial networks.In or-der to improve resource utilization,the spectrum is shared not only within each component but also be-tween satellite beams and terrestrial cells,which intro-duces inter-component interferences.To this end,this paper first proposes an analytical framework which considers the inter-component interferences induced by spectrum sharing(SS).An intelligent SS scheme based on radio map(RM)consisting of LSTM-based beam prediction(BP),transfer learning-based spec-trum prediction(SP)and joint non-preemptive prior-ity and preemptive priority(J-NPAP)-based propor-tional fair spectrum allocation is than proposed.The simulation result shows that the spectrum utilization rate of CB-STSSN is improved and user blocking rate and waiting probability are decreased by the proposed scheme.展开更多
The cloud fraction （CF） and cloud-base heights （CBHs）, and cirrus properties, over a site in southeastern China from June 2008 to May 2009, are examined by a ground-based lidar. Results show that clouds occupied t...The cloud fraction （CF） and cloud-base heights （CBHs）, and cirrus properties, over a site in southeastern China from June 2008 to May 2009, are examined by a ground-based lidar. Results show that clouds occupied the sky 41% of the time. Significant seasonal variations in CF were found with a maximum/minimum during winter/summer and similar magnitudes of CF in spring and autumn. A distinct diurnal cycle in the overall mean CF was seen. Total, daytime, and nighttime annual mean CBHs were 3.05 ± 2.73 km, 2.46 ± 2.08 kin, and 3.51 ± 3.07 km, respectively. The lowest/highest CBH occurred around noon/midnight. Cirrus clouds were present ～36.2% of the time at night with the percentage increased in summer and decreased in spring. Annual mean values for cirrus geometrical properties were 8.89 ± 1.65 km, 9.80 ± 1.70 kin, 10.73 ± 1.86 km and 1.83± 0.91 km for the base, mid-cloud, top height, and the thickness, respectively. Seasonal variations in cirrus geometrical properties show a maximum/minimum in summer/winter for all cirrus geometrical parameters. The mean cirrus lidar ratio for all cirrus cases in our study was ～ 25 ± 17 sr, with a smooth seasonal trend. The cirrus optical depth ranged from 0.001 to 2.475, with a mean of 0.34 ± 0.33. Sub-visual, thin, and dense cirrus were observed in ～12%, 43%, and 45% of the cases, respectively. More frequent, thicker cirrus clouds occurred in summer than in any other season. The properties of cirrus cloud over the site are compared with other lidar-based retrievals of midlatitude cirrus cloud properties.展开更多
An e-tag used on the freeway is a kind of passive sensors composed of sensors and radio- frequency identification （RFID） tags. The principle of the electronic toll collection system is that the sensor emits radio wa...An e-tag used on the freeway is a kind of passive sensors composed of sensors and radio- frequency identification （RFID） tags. The principle of the electronic toll collection system is that the sensor emits radio waves touching the e-tag within a certain range, the e-tag will respond to the radio waves by induction, and the sensor will read and write information of the vehicles. Although the RFID technology is popularly used in campus management systems, there is no e-tag technology application used in a campus parking system. In this paper, we use the e-tag technology on a campus parking management system based on the cloud-based construction. By this, it helps to achieve automated and standardized management of the campus parking system, enhance management efficiency, reduce the residence time of the vehicles at the entrances and exits, and improve the efficiency of vehicles parked at the same time.展开更多
Mixed redundancy strategies are generally used in cloud-based systems,with different node switch mechanisms from traditional fault-tolerant strategies.Existing studies often concentrate on optimizing a single strategy...Mixed redundancy strategies are generally used in cloud-based systems,with different node switch mechanisms from traditional fault-tolerant strategies.Existing studies often concentrate on optimizing a single strategy in cloud computing environment and ignore the impact of mixed redundancy strategies.Therefore,a model is proposed to evaluate and optimize the reliability and performance of cloud-based degraded systems subject to a mixed active and cold standby redundancy strategy.In this strategy,node switching is triggered by a continual monitoring and detection mechanism when active nodes fail.To evaluate the transient availability and the expected job completion rate of systems with such kind of strategy,a continuous-time Markov chain model is built on the state transition process and a numerical method is used to solve the model.To choose the optimal redundancy for the mixed strategy under system constraints,a greedy search algorithm is proposed after sensitivity analysis.Illustrative examples were presented to explain the process of calculating the transient probability of each system state and in turn,the availability and performance of the whole system.It was shown that the near-optimal redundancy solution could be obtained using the optimizationmethod.The comparison with optimization of the traditional mixed redundancy strategy proved that the system behavior was different using different kinds of mixed strategies and less redundancy was assigned for the new type of mixed strategy under the same system constraint.展开更多
The article presents a methodology for transitioning to the Amsterdam height system based on utilizing global and regional geoid/quasi-geoid models.The study was conducted for the Polish-Ukrainian cross-border sector ...The article presents a methodology for transitioning to the Amsterdam height system based on utilizing global and regional geoid/quasi-geoid models.The study was conducted for the Polish-Ukrainian cross-border sector and expanded to the entire territory of Poland and Ukraine.The input data comprised two regional and five global geoid/quasi-geoid models.The initial data analysis was conducted for all models relative to GNSS/leveling data in the Baltic height system.The secondary analysis was performed relative to the combined PL-quasi-geoid2021 model and the gravimetric EGG2015 model.Based on the analysis results,a methodology for optimizing heights between regional and global geoid/quasi-geoid models was developed,including the following stages:calculation of conditional global and regional geoid/quasi-geoid heights,calculation of approximately predicted height differences between the conditional regional and global geoid/quasi-geoid,implementation of the refinement(correction)of approximate heights at the regional model,optimization of approximate heights at the regional model,and calculation of a regional combined model in the Amsterdam height system.The developed methodology enables the integration of regional and global geoid/quasi-geoid models into the Amsterdam height system with an accuracy of 1-2 cm by optimizing their heights.The advantage of this methodology is that it requires only a minimal amount of GNSS/leveling data to establish connections between different height systems.展开更多
Plant height(PH),primary lateral branch length(PBL),and branch number(BN)are architectural components impacting peanut pod yield,biomass production,and adaptivity to mechanical harvesting.In this study,a recombinant i...Plant height(PH),primary lateral branch length(PBL),and branch number(BN)are architectural components impacting peanut pod yield,biomass production,and adaptivity to mechanical harvesting.In this study,a recombinant inbred population consisting of 181 individual lines was used to determine genetic controls of PH,PBL,and BN across three environments.Phenotypic data collected from the population demonstrated continuous distributions and transgressive segregation patterns.Broad-sense heritability of PH,PBL,and BN was found to be 0.87,0.88,and 0.92,respectively.Unconditional individual environmental analysis revealed 35 additive QTLs with phenotypic variation explained(PVE)ranging from 4.57 to 21.68%.A two-round meta-analysis resulted in 24consensus and 19 unique QTLs.Five unique QTLs exhibited pleiotropic effects and their genetic bases(pleiotropy or tight linkage)were evaluated.A joint analysis was performed to estimate the QTL by environment interaction(QEI)effects on PH,PBL,and BN,collectively explaining phenotypic variations of 10.80,11.02,and 7.89%,respectively.We identified 3 major and stable QTL regions(uq9-3,uq10-2,and uq16-1)on chromosomes 9,10,and 16,spanning1.43-1.53 Mb genomic regions.Candidate genes involved in phytohormones biosynthesis,signaling,and cell wall development were proposed to regulate these morphological traits.These results provide valuable information for further genetic studies and the development of molecular markers applicable to peanut architecture improvement.展开更多
This article delves Chern's conjecture for hypersurfaces with constant second fundamental form squared length S in the spherical space.At present,determining whether the third gap point of S is 2n remains unsolved...This article delves Chern's conjecture for hypersurfaces with constant second fundamental form squared length S in the spherical space.At present,determining whether the third gap point of S is 2n remains unsolved yet.First,we investigate the height functions and their properties of the position vector and normal vector in natural coordinate vectors,and then prove the existence of a Simons-type integral formula on the hypersurface that simultaneously includes the first,second,and third gap point terms of S.These results can provide new avenues of thought and methods for solving Chern's conjecture.展开更多
The mining height of a coal seam is a critical factor influencing the detachment,collapse,and formation of the collapse angle of the strata during strata movement.To clarify the mechanism by which mining height affect...The mining height of a coal seam is a critical factor influencing the detachment,collapse,and formation of the collapse angle of the strata during strata movement.To clarify the mechanism by which mining height affects strata movement characteristics,a physical model experiment was conducted based on the geological conditions of the Panel 122104 in Caojiatan Coal Mine in Shaanxi.The experiment examined strata movement at mining heights of 1 m and 10 m,identifying differences in detachment,collapse behavior,and collapse angles under these two conditions.The results indicate the following:Delamination range directly governs collapse patterns,with higher stress concentration accelerating delamination initiation and expanding affected zones.1 m mining height exhibits a“superposed fixed beam”structure with lower strength compared to the“fixed beam+cantilever beam”configuration under 10 m height.A model estimating collapse step shows 9.13%average error.Strata structure dictates collapse angle mechanisms:Pseudo-plastic deformation under 1 m height determines collapse angle through vertical tensile stress boundaries,whereas 10 m height exhibits brittle fracture behavior with collapse angles approximating fracture angles.Periodic collapse volume above working face directly correlates with mine pressure intensity and is positively correlated with the caving step distance,collapse angle,and caving range.These parameters show higher values under 10 m mining height,resulting in more pronounced mine pressure manifestations compared to 1 m conditions.展开更多
Accurately forecasting the triple point(TP)path is essential for analyzing blast loads and assessing the destructive effectiveness of the height of burst explosion.Empirical models that describe the TP path under norm...Accurately forecasting the triple point(TP)path is essential for analyzing blast loads and assessing the destructive effectiveness of the height of burst explosion.Empirical models that describe the TP path under normal temperature and pressure environments are commonly employed;however,in certain configurations,such as at high-altitudes(HAs),the environment may involve low temperature and pressure conditions.The present study develops a theoretical prediction model for the TP path under reduced pressure and temperature conditions,utilizing the image bursts method,reflected polar analysis,and dimensional analysis.The model's accuracy is evaluated through numerical simulations and experimental data.Results indicate that the prediction model effectively evaluates the TP path under diminished temperature and pressure conditions,with most predictions falling within a±15%deviation.It was found that the TP height increases with altitude.As the altitude rises from 0 m to 10,000 m,the average TP height increases by 61.7%,87.9%,109.0%,and 134.3%for the scaled height of burst of 1.5 m,2.0 m,2.5 m,and 3.0 m,respectively.Moreover,the variation in TP height under HA environments closely mirrors that observed under corresponding reduced pressure conditions.In HA environments,only the effect of low-pressure conditions on the TP path needs to be considered,as the environmental lowtemperature has a minimal effect.展开更多
Rib spalling is a highly severe issue during mining in deep-buried large-mining-height working faces.This study takes Zhaogu No.2 Coal Mine in Jiaozuo Coalfield,China,as the research background and carries out three f...Rib spalling is a highly severe issue during mining in deep-buried large-mining-height working faces.This study takes Zhaogu No.2 Coal Mine in Jiaozuo Coalfield,China,as the research background and carries out three focused works to address this problem.Firstly,field measurements were conducted to clarify rib spalling characteristics:the coal wall is dominated by shear failure,internal cracks are mainly distributed 3–6 m above the coal wall surface,and the maximum depth of crack development reaches 3 m.Secondly,Universal Distinct Element Code(UDEC)numerical simulation software was used to build a rib spalling model,with the Trigon model adopted to divide the coal wall into blocks.Analysis of four key factors shows that increased buried depth and mining height significantly raise the total length of coal wall internal cracks,increasing rib spalling risk,while higher coal body strength and support strength effectively alleviate this phenomenon.Finally,an orthogonal experiment was designed to quantitatively determine the influence degree of the four factors on rib spalling.Results show that coal body strength has the greatest impact,followed by support strength,mining height,and mining depth in order of influence.This study provides valuable theoretical guidance for on-site prevention and control of coal wall rib spalling.展开更多
Highly accurate international height reference frames with long-term stability,global consistency,and homogeneity are crucial for monitoring sea level variations,understanding climate change,managing disasters,and sup...Highly accurate international height reference frames with long-term stability,global consistency,and homogeneity are crucial for monitoring sea level variations,understanding climate change,managing disasters,and supporting other applications that benefit scientific research and societal well-being.Currently,there are over 100 local height reference systems worldwide.Unifying these systems is a pivotal step toward constructing international height reference frames.The method introduced in this study-the gravity frequency shift via Satellite Frequency Signal Transfer(SFST)-represents a groundbreaking relativistic geodetic approach,demonstrating its potential to surpass the constraints of conventional techniques.The advent of high-precision optical atomic clocks(OAC)with an accuracy level of 1×10^(-18) has facilitated this method's implementation.The International Association of Geodesy(IAG)has established the International Height Reference System(IHRS)and its practical realization,the International Height Reference Frame(IHRF).Our study focuses on two neighbouring height systems:the China Height System(CHS)and the Nepal Height System(NHS),separated by the Himalayas and the Xizang plateau.We aim to unify these two systems by determining the geopotential and orthometric height differences between their respective height datum stations:the Qingdao Height Datum Station(QHDS)and the Madar Height Datum Station(MHDS)using a simulation experiment with the method mentioned above.Using an OAC with an accuracy of 1×10^(-18),we identified a geopotential difference of-8.348±0.464 m^(2)s^(-2) and an orthometric height difference of 0.786±0.047 m between QHDS and MHDS.These results suggest that the introduced method could unify any two height systems with fewcentimeter-level precision,emphasizing its significance in contributing to the construction of the IHRS/IHRF with today's required precision.In summary,the SFST technique is a novel geodetic method that offers an alternative for height system unification,delivering centimeter-level precision,surpassing traditional methods,and supporting the development of the IHRF.展开更多
Timely identification and forecast of maize tasseling date(TD)are very important for agronomic management,yield prediction,and crop phenotype estimation.Remote sensing-based phenology monitoring has mostly relied on t...Timely identification and forecast of maize tasseling date(TD)are very important for agronomic management,yield prediction,and crop phenotype estimation.Remote sensing-based phenology monitoring has mostly relied on time series spectral index data of the complete growth season.A recent development in maize phenology detection research is to use canopy height(CH)data instead of spectral indices,but its robustness in multiple treatments and stages has not been confirmed.Meanwhile,because data of a complete growth season are needed,the need for timely in-season TD identification remains unmet.This study proposed an approach to timely identify and forecast the maize TD.We obtained RGB and light detection and ranging(Li DAR)data using the unmanned aerial vehicle platform over plots of different maize varieties under multiple treatments.After CH estimation,the feature points(inflection point)from the Logistic curve of the CH time series were extracted as TD.We examined the impact of various independent variables(day of year vs.accumulated growing degree days(AGDD)),sensors(RGB and Li DAR),time series denoise methods,different feature points,and temporal resolution on TD identification.Lastly,we used early CH time series data to predict height growth and further forecast TD.The results showed that using the 99th percentile of plot scale digital surface model and the minimum digital terrain model from Li DAR to estimate maize CH was the most stable across treatments and stages(R~2:0.928 to0.943).For TD identification,the best performance was achieved by using Li DAR data with AGDD as the independent variable,combined with the knee point method,resulting in RMSE of 2.95 d.The high accuracy was maintained at temporal resolutions as coarse as 14 d.TD forecast got more accurate as the CH time series extended.The optimal timing for forecasting TD was when the CH exceeded half of its maximum.Using only Li DAR CH data below 1.6 m and empirical growth rate estimates,the forecasted TD showed an RMSE of 3.90 d.In conclusion,this study exploited the growth characteristics of maize height to provide a practical approach for the timely identification and forecast of maize TD.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2021YFC2802501)the National Natural Science Foundation of China(Grant Nos.42175154 and 42305084)+1 种基金the Hunan Provincial Natural Science Foundation of China(Grant No.2024JJ2058)Research Project of the National University of Defense Technology(Grant No.202401-YJRC-XX-030)。
文摘Antarctic clouds and their vertical structures play a significant role in influencing the regional radiation budget and ice mass balance;however,substantial uncertainties persist.Continuous monitoring and research are essential for enhancing our understanding of these clouds.This study presents an analysis of cloud occurrence frequency and cloud-base heights(CBHs)at Zhongshan Station in East Antarctica for the first time,utilizing data from a C12 ceilometer covering the period from January 2022 to December 2023.The findings indicate that low clouds dominate at Zhongshan Station,with an average cloud occurrence frequency of 75%.Both the cloud occurrence frequency and CBH distribution exhibit distinct seasonal variations.Specifically,the cloud occurrence frequency during winter is higher than that observed in summer,while winter clouds can develop to greater heights.Over the Southern Ocean,the cloud occurrence frequency during summer surpasses that at Zhongshan Station,with clouds featuring lower CBHs and larger extinction coefficients.Furthermore,it is noteworthy that CBHs derived from the ceilometer are basically consistent with those obtained from radiosondes.Importantly,ERA5 demonstrates commendable performance in retrieving CBHs at Zhongshan Station when compared with ceilometer measurements.
基金the Ministry of Science and Technology of China (Grant Nos. 2017YFC1501701, 2017YFC1501401, 2017YFA0603501 and 2016YFA0600403)the National Natural Science Foundation of China (Grant Nos. 91544217, 41771399 and 41471301)+1 种基金the Chinese Academy of Meteorological Sciences (Grant Nos. 2017Z005 and 2017R001)the Fundamental Research Funds for the Central Universities (Grant No. 2017STUD17)
文摘Clouds are critical to the global radiation budget and hydrological cycle, but knowledge is still poor concerning the observed climatology of cloud-base height （CBH） in China. Based on fine-resolution sounding observations from the China Radiosonde Network （CRN）, the method used to estimate CBH was modified, and uncertainty analyses indicated that the CBH is good enough. The accuracy of CBH estimation is verified by the comparison between the sounding-derived CBHs and those estimated from the micro-pulse lidar and millimeter-wave cloud radar. As such, the CBH climatology was compiled for the period 2006-16. Overall, the CBH exhibits large geographic variability across China, at both 0800 Local Standard Time （LST） and 2000 LST, irrespective of season. In addition, the summertime cloud base tends to be elevated to higher altitudes in dry regions [i.e., Inner Mongolia and the North China Plain （NCP）]. By comparison, the Tibetan Plateau （TP）, Pearl River Delta （PRD） and Sichuan Basin （SCB） have relatively low CBHs （〈 2.4 km above ground level）. In terms of seasonality, the CBH reaches its maximum in summer and minimum in winter. A low cloud base tends to occur frequently （〉 70%） over the TP, PRD and SCB. In contrast, at most sites over the Yangtze River Delta （YRD） and the NCP, about half the cloud belongs to the high-cloud category. The CBH does not exhibit marked diurnal variation in summer, throughout all CRN sites, probably due to the persistent cloud coverage caused by the East Asia Summer Monsson. To the best of our knowledge, this is the first CBH climatology produced from sounding measurements in China, and provides a useful reference for obtaining observational cloud base information.
基金support from the National Key R&D Program of China under Grants Nos.2017YFC1501401 and 2017YFC0212803the National Natural Science Foundation under Grant No.41771399the Chinese Academy of Meteorological Sciences under Grant No.2018Y014。
文摘The satellite-based quantification of cloud radiative forcing remains poorly understood,due largely to the limitation or uncertainties in characterizing cloud-base height(CBH).Here,we use the CBH data from radiosonde measurements over China in combination with the collocated cloud-top height(CTH) and cloud properties from MODIS/Aqua to quantify the impact of CBH on shortwave cloud radiative forcing(SWCRF).The climatological mean SWCRF at the surface(SWCRFSUR),at the top of the atmosphere(SWCRFTOA),and in the atmosphere(SWCRFATM) are estimated to be-97.14,-84.35,and 12.79 W m^(-2),respectively for the summers spanning 2010 to 2018 over China.To illustrate the role of the cloud base,we assume four scenarios according to vertical profile patterns of cloud optical depth(COD).Using the CTH and cloud properties from MODIS alone results in large uncertainties for the estimation of SWCRFATM,compared with those under scenarios that consider the CBH.Furthermore,the biases of the CERES estimation of SWCRFATM tend to increase in the presence of thick clouds with low CBH.Additionally,the discrepancy of SWCRFATM relative to that calculated without consideration of CBH varies according to the vertical profile of COD.When a uniform COD vertical profile is assumed,the largest SWCRF discrepancies occur during the early morning or late afternoon.By comparison,the two-point COD vertical distribution assumption has the largest uncertainties occurring at noon when the solar irradiation peaks.These findings justify the urgent need to consider the cloud vertical structures when calculating the SWCRF which is otherwise neglected.
基金Shanxi Province Higher Education Science and Technology Innovation Fund Project(2022-676)Shanxi Soft Science Program Research Fund Project(2016041008-6)。
文摘In order to improve the efficiency of cloud-based web services,an improved plant growth simulation algorithm scheduling model.This model first used mathematical methods to describe the relationships between cloud-based web services and the constraints of system resources.Then,a light-induced plant growth simulation algorithm was established.The performance of the algorithm was compared through several plant types,and the best plant model was selected as the setting for the system.Experimental results show that when the number of test cloud-based web services reaches 2048,the model being 2.14 times faster than PSO,2.8 times faster than the ant colony algorithm,2.9 times faster than the bee colony algorithm,and a remarkable 8.38 times faster than the genetic algorithm.
文摘The integration of 5G technology with cloud-based control systems in industrial robots holds significant promise for the future of industrial automation.With its ultra-low latency,high data transfer speeds,and massive connectivity,5G is poised to revolutionize real-time communication and coordination in manufacturing environments.This paper explores the prospects and challenges of applying 5G technology in industrial robots,focusing on cloud-based control systems that enable scalable,flexible,and efficient operations.Key advantages of 5G,including improved communication speed,enhanced real-time control,scalability,and predictive maintenance capabilities,are discussed.However,the transition to 5G also presents challenges,such as network reliability,security concerns,integration with legacy systems,and high implementation costs.The paper also examines case studies in the automotive,electronics,and aerospace industries,providing real-world examples of 5G adoption in industrial automation.The conclusion highlights key insights and outlines potential research directions for overcoming existing barriers and fully realizing the potential of 5G technology in industrial robot control.
文摘The concept of sharing of personal health data over cloud storage in a healthcare-cyber physical system has become popular in recent times as it improves access quality.The privacy of health data can only be preserved by keeping it in an encrypted form,but it affects usability and flexibility in terms of effective search.Attribute-based searchable encryption(ABSE)has proven its worth by providing fine-grained searching capabilities in the shared cloud storage.However,it is not practical to apply this scheme to the devices with limited resources and storage capacity because a typical ABSE involves serious computations.In a healthcare cloud-based cyber-physical system(CCPS),the data is often collected by resource-constraint devices;therefore,here also,we cannot directly apply ABSE schemes.In the proposed work,the inherent computational cost of the ABSE scheme is managed by executing the computationally intensive tasks of a typical ABSE scheme on the blockchain network.Thus,it makes the proposed scheme suitable for online storage and retrieval of personal health data in a typical CCPS.With the assistance of blockchain technology,the proposed scheme offers two main benefits.First,it is free from a trusted authority,which makes it genuinely decentralized and free from a single point of failure.Second,it is computationally efficient because the computational load is now distributed among the consensus nodes in the blockchain network.Specifically,the task of initializing the system,which is considered the most computationally intensive,and the task of partial search token generation,which is considered as the most frequent operation,is now the responsibility of the consensus nodes.This eliminates the need of the trusted authority and reduces the burden of data users,respectively.Further,in comparison to existing decentralized fine-grained searchable encryption schemes,the proposed scheme has achieved a significant reduction in storage and computational cost for the secret key associated with users.It has been verified both theoretically and practically in the performance analysis section.
基金Supported by National Key Research and Development Program of China (Grant No.2018YFB1700704)National Natural Science Foundation of China (Grant No.52075068)。
文摘This paper presents a cloud-based data-driven design optimization system,named DADOS,to help engineers and researchers improve a design or product easily and efficiently.DADOS has nearly 30 key algorithms,including the design of experiments,surrogate models,model validation and selection,prediction,optimization,and sensitivity analysis.Moreover,it also includes an exclusive ensemble surrogate modeling technique,the extended hybrid adaptive function,which can make use of the advantages of each surrogate and eliminate the effort of selecting the appropriate individual surrogate.To improve ease of use,DADOS provides a user-friendly graphical user interface and employed flow-based programming so that users can conduct design optimization just by dragging,dropping,and connecting algorithm blocks into a workflow instead of writing massive code.In addition,DADOS allows users to visualize the results to gain more insights into the design problems,allows multi-person collaborating on a project at the same time,and supports multi-disciplinary optimization.This paper also details the architecture and the user interface of DADOS.Two examples were employed to demonstrate how to use DADOS to conduct data-driven design optimization.Since DADOS is a cloud-based system,anyone can access DADOS at www.dados.com.cn using their web browser without the need for installation or powerful hardware.
基金financially supported by the National Natural Science Foundation of China(No.61303216,No.61272457,No.U1401251,and No.61373172)the National High Technology Research and Development Program of China(863 Program)(No.2012AA013102)National 111 Program of China B16037 and B08038
文摘With the rapid development of computer technology, cloud-based services have become a hot topic. They not only provide users with convenience, but also bring many security issues, such as data sharing and privacy issue. In this paper, we present an access control system with privilege separation based on privacy protection(PS-ACS). In the PS-ACS scheme, we divide users into private domain(PRD) and public domain(PUD) logically. In PRD, to achieve read access permission and write access permission, we adopt the Key-Aggregate Encryption(KAE) and the Improved Attribute-based Signature(IABS) respectively. In PUD, we construct a new multi-authority ciphertext policy attribute-based encryption(CP-ABE) scheme with efficient decryption to avoid the issues of single point of failure and complicated key distribution, and design an efficient attribute revocation method for it. The analysis and simulation result show that our scheme is feasible and superior to protect users' privacy in cloud-based services.
基金the National Nat-ural Science Foundation of China under Grants 61771163the Natural Science Foundation for Out-standing Young Scholars of Heilongjiang Province un-der Grant YQ2020F001the Science and Technol-ogy on Communication Networks Laboratory under Grants SXX19641X072 and SXX18641X028.(Cor-respondence author:Min Jia)。
文摘Cloud-based satellite and terrestrial spectrum shared networks(CB-STSSN)combines the triple advantages of efficient and flexible net-work management of heterogeneous cloud access(H-CRAN),vast coverage of satellite networks,and good communication quality of terrestrial networks.Thanks to the complementary coverage characteristics,any-time and anywhere high-speed communications can be achieved to meet the various needs of users.The scarcity of spectrum resources is a common prob-lem in both satellite and terrestrial networks.In or-der to improve resource utilization,the spectrum is shared not only within each component but also be-tween satellite beams and terrestrial cells,which intro-duces inter-component interferences.To this end,this paper first proposes an analytical framework which considers the inter-component interferences induced by spectrum sharing(SS).An intelligent SS scheme based on radio map(RM)consisting of LSTM-based beam prediction(BP),transfer learning-based spec-trum prediction(SP)and joint non-preemptive prior-ity and preemptive priority(J-NPAP)-based propor-tional fair spectrum allocation is than proposed.The simulation result shows that the spectrum utilization rate of CB-STSSN is improved and user blocking rate and waiting probability are decreased by the proposed scheme.
基金supported by the Ministry of Science and Technology of China (Grant Nos. Change: 2013CB955802 to 2012AA120901)State Laboratory of Earth Surface Process and Resource Ecology, National Science Foundation of China (41175019)the US Department of Energy (Grant Nos. DEFG0208ER64571and DE-SC0007171)
文摘The cloud fraction （CF） and cloud-base heights （CBHs）, and cirrus properties, over a site in southeastern China from June 2008 to May 2009, are examined by a ground-based lidar. Results show that clouds occupied the sky 41% of the time. Significant seasonal variations in CF were found with a maximum/minimum during winter/summer and similar magnitudes of CF in spring and autumn. A distinct diurnal cycle in the overall mean CF was seen. Total, daytime, and nighttime annual mean CBHs were 3.05 ± 2.73 km, 2.46 ± 2.08 kin, and 3.51 ± 3.07 km, respectively. The lowest/highest CBH occurred around noon/midnight. Cirrus clouds were present ～36.2% of the time at night with the percentage increased in summer and decreased in spring. Annual mean values for cirrus geometrical properties were 8.89 ± 1.65 km, 9.80 ± 1.70 kin, 10.73 ± 1.86 km and 1.83± 0.91 km for the base, mid-cloud, top height, and the thickness, respectively. Seasonal variations in cirrus geometrical properties show a maximum/minimum in summer/winter for all cirrus geometrical parameters. The mean cirrus lidar ratio for all cirrus cases in our study was ～ 25 ± 17 sr, with a smooth seasonal trend. The cirrus optical depth ranged from 0.001 to 2.475, with a mean of 0.34 ± 0.33. Sub-visual, thin, and dense cirrus were observed in ～12%, 43%, and 45% of the cases, respectively. More frequent, thicker cirrus clouds occurred in summer than in any other season. The properties of cirrus cloud over the site are compared with other lidar-based retrievals of midlatitude cirrus cloud properties.
文摘An e-tag used on the freeway is a kind of passive sensors composed of sensors and radio- frequency identification （RFID） tags. The principle of the electronic toll collection system is that the sensor emits radio waves touching the e-tag within a certain range, the e-tag will respond to the radio waves by induction, and the sensor will read and write information of the vehicles. Although the RFID technology is popularly used in campus management systems, there is no e-tag technology application used in a campus parking system. In this paper, we use the e-tag technology on a campus parking management system based on the cloud-based construction. By this, it helps to achieve automated and standardized management of the campus parking system, enhance management efficiency, reduce the residence time of the vehicles at the entrances and exits, and improve the efficiency of vehicles parked at the same time.
基金supported by the National Natural Science Foundation of China(Grant No.61309005)the Basic and Frontier Research Program of Chongqing(Grant No.cstc2014jcyj A40015)
文摘Mixed redundancy strategies are generally used in cloud-based systems,with different node switch mechanisms from traditional fault-tolerant strategies.Existing studies often concentrate on optimizing a single strategy in cloud computing environment and ignore the impact of mixed redundancy strategies.Therefore,a model is proposed to evaluate and optimize the reliability and performance of cloud-based degraded systems subject to a mixed active and cold standby redundancy strategy.In this strategy,node switching is triggered by a continual monitoring and detection mechanism when active nodes fail.To evaluate the transient availability and the expected job completion rate of systems with such kind of strategy,a continuous-time Markov chain model is built on the state transition process and a numerical method is used to solve the model.To choose the optimal redundancy for the mixed strategy under system constraints,a greedy search algorithm is proposed after sensitivity analysis.Illustrative examples were presented to explain the process of calculating the transient probability of each system state and in turn,the availability and performance of the whole system.It was shown that the near-optimal redundancy solution could be obtained using the optimizationmethod.The comparison with optimization of the traditional mixed redundancy strategy proved that the system behavior was different using different kinds of mixed strategies and less redundancy was assigned for the new type of mixed strategy under the same system constraint.
文摘The article presents a methodology for transitioning to the Amsterdam height system based on utilizing global and regional geoid/quasi-geoid models.The study was conducted for the Polish-Ukrainian cross-border sector and expanded to the entire territory of Poland and Ukraine.The input data comprised two regional and five global geoid/quasi-geoid models.The initial data analysis was conducted for all models relative to GNSS/leveling data in the Baltic height system.The secondary analysis was performed relative to the combined PL-quasi-geoid2021 model and the gravimetric EGG2015 model.Based on the analysis results,a methodology for optimizing heights between regional and global geoid/quasi-geoid models was developed,including the following stages:calculation of conditional global and regional geoid/quasi-geoid heights,calculation of approximately predicted height differences between the conditional regional and global geoid/quasi-geoid,implementation of the refinement(correction)of approximate heights at the regional model,optimization of approximate heights at the regional model,and calculation of a regional combined model in the Amsterdam height system.The developed methodology enables the integration of regional and global geoid/quasi-geoid models into the Amsterdam height system with an accuracy of 1-2 cm by optimizing their heights.The advantage of this methodology is that it requires only a minimal amount of GNSS/leveling data to establish connections between different height systems.
基金supported by the Natural Science Foundation of Shandong Province,China(ZR2022MC045)the National Natural Science Foundation of China(32001584,32201876)+2 种基金the Major Science and Technology Program of Xinjiang Uygur Autonomous Region,China(2022A02008-3)the Breeding Project from Department of Science&Technology of Shandong Province,China(2022LZGC007)the Agricultural Scientific and the Technological Innovation Project of Shandong Academy of Agricultural Sciences,China(CXGC2023A06,CXGC2023A39 and CXGC2023A46),and the Major Scientific and Technological Achievements Cultivation Program of Shandong Academy of Agricultural Sciences,China(CXGC2025E02)。
文摘Plant height(PH),primary lateral branch length(PBL),and branch number(BN)are architectural components impacting peanut pod yield,biomass production,and adaptivity to mechanical harvesting.In this study,a recombinant inbred population consisting of 181 individual lines was used to determine genetic controls of PH,PBL,and BN across three environments.Phenotypic data collected from the population demonstrated continuous distributions and transgressive segregation patterns.Broad-sense heritability of PH,PBL,and BN was found to be 0.87,0.88,and 0.92,respectively.Unconditional individual environmental analysis revealed 35 additive QTLs with phenotypic variation explained(PVE)ranging from 4.57 to 21.68%.A two-round meta-analysis resulted in 24consensus and 19 unique QTLs.Five unique QTLs exhibited pleiotropic effects and their genetic bases(pleiotropy or tight linkage)were evaluated.A joint analysis was performed to estimate the QTL by environment interaction(QEI)effects on PH,PBL,and BN,collectively explaining phenotypic variations of 10.80,11.02,and 7.89%,respectively.We identified 3 major and stable QTL regions(uq9-3,uq10-2,and uq16-1)on chromosomes 9,10,and 16,spanning1.43-1.53 Mb genomic regions.Candidate genes involved in phytohormones biosynthesis,signaling,and cell wall development were proposed to regulate these morphological traits.These results provide valuable information for further genetic studies and the development of molecular markers applicable to peanut architecture improvement.
文摘This article delves Chern's conjecture for hypersurfaces with constant second fundamental form squared length S in the spherical space.At present,determining whether the third gap point of S is 2n remains unsolved yet.First,we investigate the height functions and their properties of the position vector and normal vector in natural coordinate vectors,and then prove the existence of a Simons-type integral formula on the hypersurface that simultaneously includes the first,second,and third gap point terms of S.These results can provide new avenues of thought and methods for solving Chern's conjecture.
文摘The mining height of a coal seam is a critical factor influencing the detachment,collapse,and formation of the collapse angle of the strata during strata movement.To clarify the mechanism by which mining height affects strata movement characteristics,a physical model experiment was conducted based on the geological conditions of the Panel 122104 in Caojiatan Coal Mine in Shaanxi.The experiment examined strata movement at mining heights of 1 m and 10 m,identifying differences in detachment,collapse behavior,and collapse angles under these two conditions.The results indicate the following:Delamination range directly governs collapse patterns,with higher stress concentration accelerating delamination initiation and expanding affected zones.1 m mining height exhibits a“superposed fixed beam”structure with lower strength compared to the“fixed beam+cantilever beam”configuration under 10 m height.A model estimating collapse step shows 9.13%average error.Strata structure dictates collapse angle mechanisms:Pseudo-plastic deformation under 1 m height determines collapse angle through vertical tensile stress boundaries,whereas 10 m height exhibits brittle fracture behavior with collapse angles approximating fracture angles.Periodic collapse volume above working face directly correlates with mine pressure intensity and is positively correlated with the caving step distance,collapse angle,and caving range.These parameters show higher values under 10 m mining height,resulting in more pronounced mine pressure manifestations compared to 1 m conditions.
基金funding from Anhui Engineering Laboratory of Explosive Materials and Technology Foundation(No.AHBP2022B-04)Natural Science Research Project of Anhui Educational Committee(No.2023AH051221)+1 种基金Anhui Provincial Natural Science Foundation(No.2208085QA26)Scientific Research Foundation for High-level Talents of Anhui University of Science and Technology for the project related to this work.
文摘Accurately forecasting the triple point(TP)path is essential for analyzing blast loads and assessing the destructive effectiveness of the height of burst explosion.Empirical models that describe the TP path under normal temperature and pressure environments are commonly employed;however,in certain configurations,such as at high-altitudes(HAs),the environment may involve low temperature and pressure conditions.The present study develops a theoretical prediction model for the TP path under reduced pressure and temperature conditions,utilizing the image bursts method,reflected polar analysis,and dimensional analysis.The model's accuracy is evaluated through numerical simulations and experimental data.Results indicate that the prediction model effectively evaluates the TP path under diminished temperature and pressure conditions,with most predictions falling within a±15%deviation.It was found that the TP height increases with altitude.As the altitude rises from 0 m to 10,000 m,the average TP height increases by 61.7%,87.9%,109.0%,and 134.3%for the scaled height of burst of 1.5 m,2.0 m,2.5 m,and 3.0 m,respectively.Moreover,the variation in TP height under HA environments closely mirrors that observed under corresponding reduced pressure conditions.In HA environments,only the effect of low-pressure conditions on the TP path needs to be considered,as the environmental lowtemperature has a minimal effect.
基金supported by the National Key Research and Development Program of China(No.2023YFC2907501)the National Natural Science Foundation of China(No.52374106)+1 种基金the China Postdoctoral Science Foundation(Grant no.2024T171006)the National Natural Science Foundation of China(Grant no.52204163).
文摘Rib spalling is a highly severe issue during mining in deep-buried large-mining-height working faces.This study takes Zhaogu No.2 Coal Mine in Jiaozuo Coalfield,China,as the research background and carries out three focused works to address this problem.Firstly,field measurements were conducted to clarify rib spalling characteristics:the coal wall is dominated by shear failure,internal cracks are mainly distributed 3–6 m above the coal wall surface,and the maximum depth of crack development reaches 3 m.Secondly,Universal Distinct Element Code(UDEC)numerical simulation software was used to build a rib spalling model,with the Trigon model adopted to divide the coal wall into blocks.Analysis of four key factors shows that increased buried depth and mining height significantly raise the total length of coal wall internal cracks,increasing rib spalling risk,while higher coal body strength and support strength effectively alleviate this phenomenon.Finally,an orthogonal experiment was designed to quantitatively determine the influence degree of the four factors on rib spalling.Results show that coal body strength has the greatest impact,followed by support strength,mining height,and mining depth in order of influence.This study provides valuable theoretical guidance for on-site prevention and control of coal wall rib spalling.
基金the National Natural Science Foundation of China(NSFC)(Grant Nos.42030105,42274011,42074019,41974034,42204006)。
文摘Highly accurate international height reference frames with long-term stability,global consistency,and homogeneity are crucial for monitoring sea level variations,understanding climate change,managing disasters,and supporting other applications that benefit scientific research and societal well-being.Currently,there are over 100 local height reference systems worldwide.Unifying these systems is a pivotal step toward constructing international height reference frames.The method introduced in this study-the gravity frequency shift via Satellite Frequency Signal Transfer(SFST)-represents a groundbreaking relativistic geodetic approach,demonstrating its potential to surpass the constraints of conventional techniques.The advent of high-precision optical atomic clocks(OAC)with an accuracy level of 1×10^(-18) has facilitated this method's implementation.The International Association of Geodesy(IAG)has established the International Height Reference System(IHRS)and its practical realization,the International Height Reference Frame(IHRF).Our study focuses on two neighbouring height systems:the China Height System(CHS)and the Nepal Height System(NHS),separated by the Himalayas and the Xizang plateau.We aim to unify these two systems by determining the geopotential and orthometric height differences between their respective height datum stations:the Qingdao Height Datum Station(QHDS)and the Madar Height Datum Station(MHDS)using a simulation experiment with the method mentioned above.Using an OAC with an accuracy of 1×10^(-18),we identified a geopotential difference of-8.348±0.464 m^(2)s^(-2) and an orthometric height difference of 0.786±0.047 m between QHDS and MHDS.These results suggest that the introduced method could unify any two height systems with fewcentimeter-level precision,emphasizing its significance in contributing to the construction of the IHRS/IHRF with today's required precision.In summary,the SFST technique is a novel geodetic method that offers an alternative for height system unification,delivering centimeter-level precision,surpassing traditional methods,and supporting the development of the IHRF.
基金supported by National Science and Technology Major Project(2022ZD0115701)Nanfan Special Project,CAAS(YBXM2305,YBXM2401,YBXM2402,PTXM2402)+1 种基金National Natural Science Foundation of China(42071426,42301427)the Agricultural Science and Technology Innovation Program of the Chinese Academy of Agricultural Sciences。
文摘Timely identification and forecast of maize tasseling date(TD)are very important for agronomic management,yield prediction,and crop phenotype estimation.Remote sensing-based phenology monitoring has mostly relied on time series spectral index data of the complete growth season.A recent development in maize phenology detection research is to use canopy height(CH)data instead of spectral indices,but its robustness in multiple treatments and stages has not been confirmed.Meanwhile,because data of a complete growth season are needed,the need for timely in-season TD identification remains unmet.This study proposed an approach to timely identify and forecast the maize TD.We obtained RGB and light detection and ranging(Li DAR)data using the unmanned aerial vehicle platform over plots of different maize varieties under multiple treatments.After CH estimation,the feature points(inflection point)from the Logistic curve of the CH time series were extracted as TD.We examined the impact of various independent variables(day of year vs.accumulated growing degree days(AGDD)),sensors(RGB and Li DAR),time series denoise methods,different feature points,and temporal resolution on TD identification.Lastly,we used early CH time series data to predict height growth and further forecast TD.The results showed that using the 99th percentile of plot scale digital surface model and the minimum digital terrain model from Li DAR to estimate maize CH was the most stable across treatments and stages(R~2:0.928 to0.943).For TD identification,the best performance was achieved by using Li DAR data with AGDD as the independent variable,combined with the knee point method,resulting in RMSE of 2.95 d.The high accuracy was maintained at temporal resolutions as coarse as 14 d.TD forecast got more accurate as the CH time series extended.The optimal timing for forecasting TD was when the CH exceeded half of its maximum.Using only Li DAR CH data below 1.6 m and empirical growth rate estimates,the forecasted TD showed an RMSE of 3.90 d.In conclusion,this study exploited the growth characteristics of maize height to provide a practical approach for the timely identification and forecast of maize TD.
