Intercity mobility lays the foundation for capital flow,information flow,and knowledge flow,etc.,and is important for promoting regional integration.Although many scholars have studied intercity mobility in extensive ...Intercity mobility lays the foundation for capital flow,information flow,and knowledge flow,etc.,and is important for promoting regional integration.Although many scholars have studied intercity mobility in extensive well-developed urban agglomerations,few studies have examined the characteristics of intercity mobility at the county level and its impact on regionalization in western China.This study takes the Guanzhong Plain urban agglomeration(GPUA)as a case to study the geographical law of intercity mobility and then explore its impact on regionalization.The results obtained show that intercity mobility network exhibits a hub and spoke patterns focusing on major municipal districts at the county level.We also found a corridor effect that counties with higher travel volumes are mostly located along the trunk high speed railway(HSR)lines.Unlike previous studies,the distribution of intercity mobility is more concentrated than that of population and exhibits a super-linear behavior rule.There are the differences in gravity law for overall trips,weekday trips,weekend trips,and holiday trips.With the decrease of travel duration,the effect of attraction of destination is weakening,but the influence of distance decay is increasing.Finally,the spatial organization is still administrative-centric and is dominated by intraprefecture and intra-provincial development.Moreover,the coupled degree between network-based regionalization and attribute-based regionalization shows a decreasing trend from administrative via cultural to physical factors.These findings enrich the research on the intercity mobility and the regionalization in inland developing urban agglomerations.展开更多
为构建综合能源系统安全域(integrated energy system security region,IESSR),该文提出一种基于多项式混沌展开(polynomial chaos expansion,PCE)的IESSR边界(IESR boundary,IESSRB)近似方法,借助该方法可得IESSRB的多项式逼近表达式...为构建综合能源系统安全域(integrated energy system security region,IESSR),该文提出一种基于多项式混沌展开(polynomial chaos expansion,PCE)的IESSR边界(IESR boundary,IESSRB)近似方法,借助该方法可得IESSRB的多项式逼近表达式。首先,根据IESSRB的边界拓扑特性,构建系统的IESSR边界点搜索优化模型;然后,根据PCE,对IESSR边界点搜索优化模型进行参数化处理,构建IESSRB搜索的参数化优化模型;进一步地,根据IESSRB搜索的参数化优化模型的KKT条件,将IESSRB的参数化优化模型转化为高维参数化非线性方程组;在此基础上,借助广义Galerkin投影构建关于近似IESSRB的多项式逼近系数的Galerkin投影方程组,通过求解该方程组可得IESSRB的多项式逼近系数,从而获得IESSRB的多项式逼近表达式;为进一步降低Galerkin投影方程组求解复杂度,提出多项式分段近似IESSRB方法,在提高IESSRB近似精度的同时,提升了IESSRB近似的计算效率;最后,通过IES E39-G20测试系统和IES E118-G96测试系统对所提方法进行分析、验证。结果表明,所提方法可实现IESSR的准确、有效构建。展开更多
To provide materials for the selection of plant species for vegetation restoration and reconstruction in the farming-pastoral zone in northern China, where the eco-environment has been already deteriorated by over-far...To provide materials for the selection of plant species for vegetation restoration and reconstruction in the farming-pastoral zone in northern China, where the eco-environment has been already deteriorated by over-farming and over-grazing, the suitable trees, shrubs and herbages were examined, screened and identified under the guidance of four principles of taking precedence for ecological conservation, being beneficial to economic production, matching species (trees, shrubs and herbages) with the site, and giving consideration to the integrity of local administrative division. According to the key ecological factors that determine species growth and distribution in the zone, i.e., the lowest daily mean temperature in a year, annual accumulated temperature, and water regimes represented by the moist index, the ratio between annual rainfall and accumulated temperature (>0 degreesC), as well as the soil type influenced by climate, surface substances and landform, the farming-pastoral zone was regionalized into seven parts: ( I) Western Songliao Plain and Da Hinggan Mountain Region; (II) Upper Liaohe River Sandy Region; (III) Mid-Eastern Nei Mongol Plateau and Northwestern Heibei Mountain Region; (IV) Luliang, Taihang and Yanshan Mountain Region; ( V) Ordos Plateau Sandy Region; (VI) Northern Shaanxi to Eastern Gansu Loess Plateau Region; and (VII) Mid Gansu to Eastern Qinghai Plateau Loess Region. And the suitable trees, shrubs and herbages for each region were selected and tabularly introduced in detail.展开更多
基金Under the auspices of National Natural Science Foundation of China(No.42371189)Central University Basic Research Fund of China(No.24ZYYB017)。
文摘Intercity mobility lays the foundation for capital flow,information flow,and knowledge flow,etc.,and is important for promoting regional integration.Although many scholars have studied intercity mobility in extensive well-developed urban agglomerations,few studies have examined the characteristics of intercity mobility at the county level and its impact on regionalization in western China.This study takes the Guanzhong Plain urban agglomeration(GPUA)as a case to study the geographical law of intercity mobility and then explore its impact on regionalization.The results obtained show that intercity mobility network exhibits a hub and spoke patterns focusing on major municipal districts at the county level.We also found a corridor effect that counties with higher travel volumes are mostly located along the trunk high speed railway(HSR)lines.Unlike previous studies,the distribution of intercity mobility is more concentrated than that of population and exhibits a super-linear behavior rule.There are the differences in gravity law for overall trips,weekday trips,weekend trips,and holiday trips.With the decrease of travel duration,the effect of attraction of destination is weakening,but the influence of distance decay is increasing.Finally,the spatial organization is still administrative-centric and is dominated by intraprefecture and intra-provincial development.Moreover,the coupled degree between network-based regionalization and attribute-based regionalization shows a decreasing trend from administrative via cultural to physical factors.These findings enrich the research on the intercity mobility and the regionalization in inland developing urban agglomerations.
文摘为构建综合能源系统安全域(integrated energy system security region,IESSR),该文提出一种基于多项式混沌展开(polynomial chaos expansion,PCE)的IESSR边界(IESR boundary,IESSRB)近似方法,借助该方法可得IESSRB的多项式逼近表达式。首先,根据IESSRB的边界拓扑特性,构建系统的IESSR边界点搜索优化模型;然后,根据PCE,对IESSR边界点搜索优化模型进行参数化处理,构建IESSRB搜索的参数化优化模型;进一步地,根据IESSRB搜索的参数化优化模型的KKT条件,将IESSRB的参数化优化模型转化为高维参数化非线性方程组;在此基础上,借助广义Galerkin投影构建关于近似IESSRB的多项式逼近系数的Galerkin投影方程组,通过求解该方程组可得IESSRB的多项式逼近系数,从而获得IESSRB的多项式逼近表达式;为进一步降低Galerkin投影方程组求解复杂度,提出多项式分段近似IESSRB方法,在提高IESSRB近似精度的同时,提升了IESSRB近似的计算效率;最后,通过IES E39-G20测试系统和IES E118-G96测试系统对所提方法进行分析、验证。结果表明,所提方法可实现IESSR的准确、有效构建。
文摘To provide materials for the selection of plant species for vegetation restoration and reconstruction in the farming-pastoral zone in northern China, where the eco-environment has been already deteriorated by over-farming and over-grazing, the suitable trees, shrubs and herbages were examined, screened and identified under the guidance of four principles of taking precedence for ecological conservation, being beneficial to economic production, matching species (trees, shrubs and herbages) with the site, and giving consideration to the integrity of local administrative division. According to the key ecological factors that determine species growth and distribution in the zone, i.e., the lowest daily mean temperature in a year, annual accumulated temperature, and water regimes represented by the moist index, the ratio between annual rainfall and accumulated temperature (>0 degreesC), as well as the soil type influenced by climate, surface substances and landform, the farming-pastoral zone was regionalized into seven parts: ( I) Western Songliao Plain and Da Hinggan Mountain Region; (II) Upper Liaohe River Sandy Region; (III) Mid-Eastern Nei Mongol Plateau and Northwestern Heibei Mountain Region; (IV) Luliang, Taihang and Yanshan Mountain Region; ( V) Ordos Plateau Sandy Region; (VI) Northern Shaanxi to Eastern Gansu Loess Plateau Region; and (VII) Mid Gansu to Eastern Qinghai Plateau Loess Region. And the suitable trees, shrubs and herbages for each region were selected and tabularly introduced in detail.
