In several LUCC studies, statistical methods are being used to analyze land use data. A problem using conventional statistical methods in land use analysis is that these methods assume the data to be statistically ind...In several LUCC studies, statistical methods are being used to analyze land use data. A problem using conventional statistical methods in land use analysis is that these methods assume the data to be statistically independent. But in fact, they have the tendency to be dependent, a phenomenon known as multicollinearity, especially in the cases of few observations. In this paper, a Partial Least-Squares （PLS） regression approach is developed to study relationships between land use and its influencing factors through a case study of the Suzhou-Wuxi-Changzhou region in China. Multicollinearity exists in the dataset and the number of variables is high compared to the number of observations. Four PLS factors are selected through a preliminary analysis. The correlation analyses between land use and influencing factors demonstrate the land use character of rural industrialization and urbanization in the Suzhou-Wuxi-Changzhou region, meanwhile illustrate that the first PLS factor has enough ability to best describe land use patterns quantitatively, and most of the statistical relations derived from it accord with the fact. By the decreasing capacity of the PLS factors, the reliability of model outcome decreases correspondingly.展开更多
Human beings’ intellection is the characteristic of a distinct hierarchy and can be taken to construct a heuristic in the shortest path algorithms.It is detailed in this paper how to utilize the hierarchical reasonin...Human beings’ intellection is the characteristic of a distinct hierarchy and can be taken to construct a heuristic in the shortest path algorithms.It is detailed in this paper how to utilize the hierarchical reasoning on the basis of greedy and directional strategy to establish a spatial heuristic,so as to improve running efficiency and suitability of shortest path algorithm for traffic network.The authors divide urban traffic network into three hierarchies and set forward a new node hierarchy division rule to avoid the unreliable solution of shortest path.It is argued that the shortest path,no matter distance shortest or time shortest,is usually not the favorite of drivers in practice.Some factors difficult to expect or quantify influence the drivers’ choice greatly.It makes the drivers prefer choosing a less shortest,but more reliable or flexible path to travel on.The presented optimum path algorithm,in addition to the improvement of the running efficiency of shortest path algorithms up to several times,reduces the emergence of those factors,conforms to the intellection characteristic of human beings,and is more easily accepted by drivers.Moreover,it does not require the completeness of networks in the lowest hierarchy and the applicability and fault tolerance of the algorithm have improved.The experiment result shows the advantages of the presented algorithm.The authors argued that the algorithm has great potential application for navigation systems of large_scale traffic networks.展开更多
Oceanic pycnocline depth is usually inferred from in situ measurements. It is attempted to estimate the depth remotely. As solitary internal waves occur on oceanic pycnocline and propagate along it, it is possible to ...Oceanic pycnocline depth is usually inferred from in situ measurements. It is attempted to estimate the depth remotely. As solitary internal waves occur on oceanic pycnocline and propagate along it, it is possible to retrieve the depth indirectly in virtue of the solitary internal waves. A numerical model is presented for retrieving the pycnocline depth from synthetic aperture radar （SAR） images where the solitary internal waves are visible and when ocean waters are fully stratified. This numerical model is constructed by combining the solitary internal wave model and a two-layer ocean model. It is also assumed that the observed groups of solitary internal wave packets on the SAR imagery are generated by local semidiurnal tides. A case study in the East China Sea shows a good agreement with in situ CTD （conductivity-temperature-depth） data.展开更多
Popular regional inequality indexes such as variation coefficient and Gini coefficient can only reveal overall inequality, and have limited ability in revealing spatial dependence or spatial agglomeration. Recently so...Popular regional inequality indexes such as variation coefficient and Gini coefficient can only reveal overall inequality, and have limited ability in revealing spatial dependence or spatial agglomeration. Recently some methods of exploratory spatial data analysis such as spatial autocorrelation have provided effective tools to analyze spatial agglomeration and cluster, which can reveal the pattern of regional inequality. This article attempts to use spatial autocorrelation at county level to get refined spatial pattern of regional disparity in Chinese northeast economic region over 2000-2006 (2001 absent). The result indicates that the basic trend of regional economy is an increasing concentration of growth among counties in northeast economic region, and there are two geographical clusters of poorer counties including the counties in western Liaoning Province and adjacent counties in Inner Mongolia, poorer counties of Heihe, Qiqihar and Suihua in Heilongjiang Province. This article also reveals that we can use the methods of exploratory spatial data analysis as the supplementary analysis methods in regional economic analysis.展开更多
In the new era of earth system science in conjunction with the digital revolution,new platforms and programs are required for facilitating the utilization of geoscience data,especially to improve the integration of st...In the new era of earth system science in conjunction with the digital revolution,new platforms and programs are required for facilitating the utilization of geoscience data,especially to improve the integration of structured data with unstructured data for solving complex problems.Big data is not just matter of size but most importantly how easily and effectively it can be used.A major goal is to facilitate a move from traditional scientific approaches to a more modern approach that involves big data analytics.展开更多
The construction of oceanographic ontologies is fundamental to the ＂digital ocean＂. Therefore, on the basis of introduction of new concept of oceanographic ontology, an oceanographic ontology-based spatial knowledge...The construction of oceanographic ontologies is fundamental to the ＂digital ocean＂. Therefore, on the basis of introduction of new concept of oceanographic ontology, an oceanographic ontology-based spatial knowledge query （OOBSKQ） method was proposed and developed. Because the method uses a natural language to describe query conditions and the query result is highly integrated knowledge, it can provide users with direct answers while hiding the complicated computation and reasoning processes, and achieves intelligent, automatic oceanographic spatial information query on the level of knowledge and semantics. A case study of resource and environmental application in bay has shown the implementation process of the method and its feasibility and usefulness.展开更多
The eddy tracking approach is developed using the global nearest neighbor filter（GNNF） to investigate the evolution processes and behaviors of mesoscale eddies in the South China Sea（SCS）. Combining the Kalman fil...The eddy tracking approach is developed using the global nearest neighbor filter（GNNF） to investigate the evolution processes and behaviors of mesoscale eddies in the South China Sea（SCS）. Combining the Kalman filter and optimal data association technologies, the GNNF algorithm is able to reduce pairing errors to 0.2% in tracking synthetic eddy tracks, outperforming other existing methods. A total of 4 913 eddy tracks that last more than a week are obtained by the GNNF during 1993–2012. The analysis of a growth and a decay based on 3 445 simple eddy tracks show that eddy radius, amplitude, and vorticity smoothly increase during the first half of lifetime and decline during the second half following a parabola opening downwards. The genesis of eddies mainly clusters northwest and southwest of Luzon Island whereas the dissipations concentrate the Xisha Islands where the underwater bay traps and terminates eddies. West of the Luzon Strait, northwest of Luzon Island, and southeast of Vietnam are regions where eddy splits and mergers are frequently observed. Short disappearances mainly distribute in the first two regions. Moreover, eddy splits generally result in a decrease of the radius and the amplitude whereas eddy mergers induce growing up. Eddy intensity and vorticity, on the contrary, are strengthened in the eddy splits and diminished in mergers.展开更多
Analysis of ocean fronts＇ uncertainties indicates that they result from indiscemibility of their spatial position and fuzziness of their intensity. In view of this, a flow hierarchy for uncertainty representation of ...Analysis of ocean fronts＇ uncertainties indicates that they result from indiscemibility of their spatial position and fuzziness of their intensity. In view of this, a flow hierarchy for uncertainty representation of ocean fronts is proposed on the basis of fuzzy-rough set theory. Firstly, raster scanning and blurring are carried out on an ocean front, and the upper and lower approximate sets, the indiscernible relation in fuzzy-rough theories and related operators in fuzzy set theories are adopted to represent its uncertainties, then they are classified into three sets： with members one hundred percent belonging to the ocean front, belonging to the ocean front＇s edge and definitely not belonging to the ocean front. Finally, the approximate precision and roughness degree are utilized to evaluate the ocean front＇s degree of uncertainties and the precision of the representation. It has been proven that the method is not only capable of representing ocean fronts＇ uncertainties, but also provides a new theory and method for uncertainty representation of other oceanic phenomena.展开更多
Changes in surface temperature extremes have become a global concern.Based on the daily lowest temperature(TN)and daily highest temperature(TX)data from 2138weather stations in China from 1961 to 2020,we calculated 14...Changes in surface temperature extremes have become a global concern.Based on the daily lowest temperature(TN)and daily highest temperature(TX)data from 2138weather stations in China from 1961 to 2020,we calculated 14 extreme temperature indices to analyze the characteristics of extreme temperature events.The widespread changes observed in all extreme temperature indices suggest that China experienced significant warming during this period.Specifically,the cold extreme indices,such as cold nights,cold days,frost days,icing days,and the cold spell duration index,decreased significantly by-6.64,-2.67,-2.96,-0.97,and-1.01 days/decade,respectively.In contrast,we observed significant increases in warm extreme indices.The number of warm nights,warm days,summer days,tropical nights,and warm spell duration index increased by 8.44,5.18,2.81,2.50,and 1.66d/decade,respectively.In addition,the lowest TN,highest TN,lowest TX,and highest TX over the entire period rose by 0.47,0.22,0.26,and 0.16℃/decade,respectively.Furthermore,using Pearson's correlation and wavelet coherence analyses,this study identified a strong association between extreme temperature indices and atmospheric circulation factors,with varying correlation strengths and resonance periods across different time-frequency domains.展开更多
基金National Natural Science Foundation of China No.40301038
文摘In several LUCC studies, statistical methods are being used to analyze land use data. A problem using conventional statistical methods in land use analysis is that these methods assume the data to be statistically independent. But in fact, they have the tendency to be dependent, a phenomenon known as multicollinearity, especially in the cases of few observations. In this paper, a Partial Least-Squares （PLS） regression approach is developed to study relationships between land use and its influencing factors through a case study of the Suzhou-Wuxi-Changzhou region in China. Multicollinearity exists in the dataset and the number of variables is high compared to the number of observations. Four PLS factors are selected through a preliminary analysis. The correlation analyses between land use and influencing factors demonstrate the land use character of rural industrialization and urbanization in the Suzhou-Wuxi-Changzhou region, meanwhile illustrate that the first PLS factor has enough ability to best describe land use patterns quantitatively, and most of the statistical relations derived from it accord with the fact. By the decreasing capacity of the PLS factors, the reliability of model outcome decreases correspondingly.
文摘Human beings’ intellection is the characteristic of a distinct hierarchy and can be taken to construct a heuristic in the shortest path algorithms.It is detailed in this paper how to utilize the hierarchical reasoning on the basis of greedy and directional strategy to establish a spatial heuristic,so as to improve running efficiency and suitability of shortest path algorithm for traffic network.The authors divide urban traffic network into three hierarchies and set forward a new node hierarchy division rule to avoid the unreliable solution of shortest path.It is argued that the shortest path,no matter distance shortest or time shortest,is usually not the favorite of drivers in practice.Some factors difficult to expect or quantify influence the drivers’ choice greatly.It makes the drivers prefer choosing a less shortest,but more reliable or flexible path to travel on.The presented optimum path algorithm,in addition to the improvement of the running efficiency of shortest path algorithms up to several times,reduces the emergence of those factors,conforms to the intellection characteristic of human beings,and is more easily accepted by drivers.Moreover,it does not require the completeness of networks in the lowest hierarchy and the applicability and fault tolerance of the algorithm have improved.The experiment result shows the advantages of the presented algorithm.The authors argued that the algorithm has great potential application for navigation systems of large_scale traffic networks.
基金This project was supported by the National Natural Science Foundation of China under contract No.40206023the National Hi-Tech Project(“863”Program)of China under contract Nos 2002AA639360 and 2002AA633120.
文摘Oceanic pycnocline depth is usually inferred from in situ measurements. It is attempted to estimate the depth remotely. As solitary internal waves occur on oceanic pycnocline and propagate along it, it is possible to retrieve the depth indirectly in virtue of the solitary internal waves. A numerical model is presented for retrieving the pycnocline depth from synthetic aperture radar （SAR） images where the solitary internal waves are visible and when ocean waters are fully stratified. This numerical model is constructed by combining the solitary internal wave model and a two-layer ocean model. It is also assumed that the observed groups of solitary internal wave packets on the SAR imagery are generated by local semidiurnal tides. A case study in the East China Sea shows a good agreement with in situ CTD （conductivity-temperature-depth） data.
基金supported by the National Natural Science Foundation for Distinguished Young Scholar of China (Grant No.40225004)
文摘Popular regional inequality indexes such as variation coefficient and Gini coefficient can only reveal overall inequality, and have limited ability in revealing spatial dependence or spatial agglomeration. Recently some methods of exploratory spatial data analysis such as spatial autocorrelation have provided effective tools to analyze spatial agglomeration and cluster, which can reveal the pattern of regional inequality. This article attempts to use spatial autocorrelation at county level to get refined spatial pattern of regional disparity in Chinese northeast economic region over 2000-2006 (2001 absent). The result indicates that the basic trend of regional economy is an increasing concentration of growth among counties in northeast economic region, and there are two geographical clusters of poorer counties including the counties in western Liaoning Province and adjacent counties in Inner Mongolia, poorer counties of Heihe, Qiqihar and Suihua in Heilongjiang Province. This article also reveals that we can use the methods of exploratory spatial data analysis as the supplementary analysis methods in regional economic analysis.
文摘In the new era of earth system science in conjunction with the digital revolution,new platforms and programs are required for facilitating the utilization of geoscience data,especially to improve the integration of structured data with unstructured data for solving complex problems.Big data is not just matter of size but most importantly how easily and effectively it can be used.A major goal is to facilitate a move from traditional scientific approaches to a more modern approach that involves big data analytics.
基金This study was supported by the“863”Marine Monitor of High-tech Research and Development Program of China under contracts Nos 2003AA604040 and 2003AA637030.
文摘The construction of oceanographic ontologies is fundamental to the ＂digital ocean＂. Therefore, on the basis of introduction of new concept of oceanographic ontology, an oceanographic ontology-based spatial knowledge query （OOBSKQ） method was proposed and developed. Because the method uses a natural language to describe query conditions and the query result is highly integrated knowledge, it can provide users with direct answers while hiding the complicated computation and reasoning processes, and achieves intelligent, automatic oceanographic spatial information query on the level of knowledge and semantics. A case study of resource and environmental application in bay has shown the implementation process of the method and its feasibility and usefulness.
基金The National Natural Science Foundation of China under contract Nos 41421001 and 41371378
文摘The eddy tracking approach is developed using the global nearest neighbor filter（GNNF） to investigate the evolution processes and behaviors of mesoscale eddies in the South China Sea（SCS）. Combining the Kalman filter and optimal data association technologies, the GNNF algorithm is able to reduce pairing errors to 0.2% in tracking synthetic eddy tracks, outperforming other existing methods. A total of 4 913 eddy tracks that last more than a week are obtained by the GNNF during 1993–2012. The analysis of a growth and a decay based on 3 445 simple eddy tracks show that eddy radius, amplitude, and vorticity smoothly increase during the first half of lifetime and decline during the second half following a parabola opening downwards. The genesis of eddies mainly clusters northwest and southwest of Luzon Island whereas the dissipations concentrate the Xisha Islands where the underwater bay traps and terminates eddies. West of the Luzon Strait, northwest of Luzon Island, and southeast of Vietnam are regions where eddy splits and mergers are frequently observed. Short disappearances mainly distribute in the first two regions. Moreover, eddy splits generally result in a decrease of the radius and the amplitude whereas eddy mergers induce growing up. Eddy intensity and vorticity, on the contrary, are strengthened in the eddy splits and diminished in mergers.
基金The research was partially funded by the Project 40571129 supported by the National Natural Science Foundation of ChinaInnovative Program(No.kzcx2-yw-304-1)supported by the Chinese Academy of Sciences.
文摘Analysis of ocean fronts＇ uncertainties indicates that they result from indiscemibility of their spatial position and fuzziness of their intensity. In view of this, a flow hierarchy for uncertainty representation of ocean fronts is proposed on the basis of fuzzy-rough set theory. Firstly, raster scanning and blurring are carried out on an ocean front, and the upper and lower approximate sets, the indiscernible relation in fuzzy-rough theories and related operators in fuzzy set theories are adopted to represent its uncertainties, then they are classified into three sets： with members one hundred percent belonging to the ocean front, belonging to the ocean front＇s edge and definitely not belonging to the ocean front. Finally, the approximate precision and roughness degree are utilized to evaluate the ocean front＇s degree of uncertainties and the precision of the representation. It has been proven that the method is not only capable of representing ocean fronts＇ uncertainties, but also provides a new theory and method for uncertainty representation of other oceanic phenomena.
基金National Key Research and Development Program of China,No.2021YFB3900900。
文摘Changes in surface temperature extremes have become a global concern.Based on the daily lowest temperature(TN)and daily highest temperature(TX)data from 2138weather stations in China from 1961 to 2020,we calculated 14 extreme temperature indices to analyze the characteristics of extreme temperature events.The widespread changes observed in all extreme temperature indices suggest that China experienced significant warming during this period.Specifically,the cold extreme indices,such as cold nights,cold days,frost days,icing days,and the cold spell duration index,decreased significantly by-6.64,-2.67,-2.96,-0.97,and-1.01 days/decade,respectively.In contrast,we observed significant increases in warm extreme indices.The number of warm nights,warm days,summer days,tropical nights,and warm spell duration index increased by 8.44,5.18,2.81,2.50,and 1.66d/decade,respectively.In addition,the lowest TN,highest TN,lowest TX,and highest TX over the entire period rose by 0.47,0.22,0.26,and 0.16℃/decade,respectively.Furthermore,using Pearson's correlation and wavelet coherence analyses,this study identified a strong association between extreme temperature indices and atmospheric circulation factors,with varying correlation strengths and resonance periods across different time-frequency domains.
