A network perspective has increasingly become an organizational paradigm for understanding regional spatial structures. Based on a critical overview of existing empirical models for estimating intercity networks based...A network perspective has increasingly become an organizational paradigm for understanding regional spatial structures. Based on a critical overview of existing empirical models for estimating intercity networks based on firm linkages, this study extends the re- cently proposed regional corporate city model algorithm by proposing a new method for ap- proximating urban networks based on the Iocational strategies of firms. The new method considers both regional and hierarchical network features and avoids the information loss associated with the conversion from two-mode firm-city networks to one-mode city-city networks. In addition, networks estimated by using the method proposed herein are suitable when employing social network analysis. Finally, this method is empirically validated by ex- amining intercity firm networks formed by advanced producer services firms in China＇s two largest metropolitan areas, namely the Yangtze River Delta and Pearl River Delta. The pre- sented empirical analysis suggests two main findings. First, in contrast to conventional methods （e.g., the interlocking city network model）, our new method produces regional and hierarchical urban networks that more closely resemble reality. Second, the new method al- lows us to use social network analysis to assess betweenness and closeness centralities. However, regardless of the model applied, the validity of any method that measures urban networks depends on the soundness of its underlying assumptions about how network actors （firms, in our case） interact.展开更多
Taking Kenli County in the Yellow River Delta, China, as the study area and using digital satellite remote sensing techniques, cultivated land use changes and their corresponding driving forces were explored in this s...Taking Kenli County in the Yellow River Delta, China, as the study area and using digital satellite remote sensing techniques, cultivated land use changes and their corresponding driving forces were explored in this study. An interactive interpretation and a manual modification procedure were carried out to acquire cultivated land information. An overlay method based on classification results and a visual change detection method which was supported by land use maps were employed to detect the cultivated land changes. Based on the changes that were revealed and a spatial analysis between cultivated land use and related natural and socio-economic factors, the driving forces for cultivated land use changes in the study area were determined.The results showed a decrease in cultivated land in Kenli County of 5321.8 ha from 1987 to 1998, i.e.,an average annual decrement of 483.8 ha, which occurred mainly in the central paddy field region and the northeast dry land region. Adverse human activities, soil salinization and water deficiencies were the driving forces that caused these cultivated land use changes.展开更多
基金National Natural Science Foundation of China, No.51478189 No.41401178+2 种基金 National Social Science Fund, 1 l＆ZD154 State Key Laboratory of Subtropical Building Science, No.2013KB20 Fundamental Research Funds for the Central Universities, No.2013ZZ0022
文摘A network perspective has increasingly become an organizational paradigm for understanding regional spatial structures. Based on a critical overview of existing empirical models for estimating intercity networks based on firm linkages, this study extends the re- cently proposed regional corporate city model algorithm by proposing a new method for ap- proximating urban networks based on the Iocational strategies of firms. The new method considers both regional and hierarchical network features and avoids the information loss associated with the conversion from two-mode firm-city networks to one-mode city-city networks. In addition, networks estimated by using the method proposed herein are suitable when employing social network analysis. Finally, this method is empirically validated by ex- amining intercity firm networks formed by advanced producer services firms in China＇s two largest metropolitan areas, namely the Yangtze River Delta and Pearl River Delta. The pre- sented empirical analysis suggests two main findings. First, in contrast to conventional methods （e.g., the interlocking city network model）, our new method produces regional and hierarchical urban networks that more closely resemble reality. Second, the new method al- lows us to use social network analysis to assess betweenness and closeness centralities. However, regardless of the model applied, the validity of any method that measures urban networks depends on the soundness of its underlying assumptions about how network actors （firms, in our case） interact.
基金Project supported by the Department of Science and Technology of Shandong Province (No. 02BS044).
文摘Taking Kenli County in the Yellow River Delta, China, as the study area and using digital satellite remote sensing techniques, cultivated land use changes and their corresponding driving forces were explored in this study. An interactive interpretation and a manual modification procedure were carried out to acquire cultivated land information. An overlay method based on classification results and a visual change detection method which was supported by land use maps were employed to detect the cultivated land changes. Based on the changes that were revealed and a spatial analysis between cultivated land use and related natural and socio-economic factors, the driving forces for cultivated land use changes in the study area were determined.The results showed a decrease in cultivated land in Kenli County of 5321.8 ha from 1987 to 1998, i.e.,an average annual decrement of 483.8 ha, which occurred mainly in the central paddy field region and the northeast dry land region. Adverse human activities, soil salinization and water deficiencies were the driving forces that caused these cultivated land use changes.
