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821.
This article explored China's urban employment dynamics with particular focus on the city size effect.Big data derived from the largest recruitment website were used to ex-amine the direct and indirect impacts of city size on employment demand by using mediating and moderating models.We also investigated the roles of the government and location fac-tors which have seldom been considered in literature.Results showed that the concentration degree of new jobs is higher than that of stock employment and population across cities,implying a path dependency mechanism of job creation and employment expansion.Mean-while,numerous job posts in inland central cities are probably a symptom of more even dis-tribution of employment in future China.Econometric models further verified the significant correlation between city size and job creation.Moreover,industrial diversity,fixed asset in-vestment,and spatial location have heterogeneous effects on employment demand in cities of different sizes and different levels of administration.These results can not only deepen our understanding of the crucial role of city size in urban employment growth but also demon-strate the future trend of labor and population geography of China.Policy implications are then proposed for job creation in cities of China and other developing countries. 相似文献
822.
Residential segregation is a dual process of socio-spatial differentiation in residents and spatio-temporal heterogeneity in dwelling.However,most of the existing studies are es-tablished from the single perspective of urban residents based on demographic data,which is difficult to reveal the dynamics and complex spatial reconstruction within and between cities.With the characteristics of both stability and timeliness,the rapidly changing housing market is one of the processes and results of socio-spatial reconfiguration,and it is undoubtedly a better lens to observe residential segregation.This paper adopts methods such as multi-group segregation index,multi-scalar segregation profiles,and decomposition of segregation index,with Nanjing and Hangzhou as case cities,and establishes multi-scalar segregation profiles and comparative models based on three geographical scales of census tract,block and grid,and different residential types.A quantitative study was conducted on the degree and pattern of multi-scalar residential segregation in Nanjing and Hangzhou from 2009 to 2018.The pa-per found that the spatial segregation index is an improvement of the non-spatial segregation index.There are differences between Nanjing and Hangzhou in the evolution process of residential segregation.Nanjing has a higher degree of spatial differentiation as a whole,among which spatial components have a more significant impact. 相似文献
823.
基于前期研究工作成果和外部环境变化因素分析,探讨了青弋江发育原因及其与长江贯通的关系。研究表明:① 昆黄运动可能在长江中下游地区产生了区域构造响应,导致研究区断层被激活而发生了较大幅度的断块抬升运动,进而为青弋江发育提供了下切驱动力,驱动了青弋江发育;② 东亚夏季风在约1.3 Ma和约0.9 Ma发生的2次显著阶段性减弱事件,引起区域降水量显著增加,进而为青弋江发育提供了下切媒介和持续水流,控制了青弋江发育年代;③ 青弋江发育与长江贯通可能都是昆黄运动区域构造响应与东亚夏季风强度阶段性减弱共同作用的结果,并且长江贯通后所形成的新局部侵蚀基准面也可能促进了青弋江发育,因此青弋江发育年代在一定程度上能反映长江贯通年代。 相似文献
824.
825.
The Indo-Pacific convergence region is the best target to solve the teo remaining challenge s of the plate tectonics theory,i.e.,subduction initiation and the driving force of plate tectonics.Recent studies proposed that the Izu-Bonin subduction initiation belongs to spontaneous initiation,which implies that it started from extension,followed by low angle subduction.Numerical geodynamic modeling suggests that the initiation of plate subduction likely occurred along a transform fault,which put the young spreading ridge in direct contact with old oceanic crust.This,however,does not explain the simultaneous subduction initiation in the west Pacific region in the Cenozoic.Namely,the subduction initiations in the Izu-BoninMariana,the Aleutian,and the Tonga-Kermadec trenches are associated with oceanic crusts of different ages,yet they occurred at roughly the same time,suggesting that they were all triggered by a maj or change in the Pacific plate.Moreover,low angle subduction induces compression rather than extension,which requires external compression forces.Given that the famous Hawaiian-Emperor bending occurred roughly at the same time with the onset of westward subductions in the west Pacific,we propose that these Cenozoic subductions were initiated by the steering of the Pacific plate,which are classified as induced initiation.Induced subduction initiation usually occurs in young ocean basins,forming single-track subduction.The closure s of Neo-Tethys Oceans were likely triggered by plume s in the south,forming northward subductions.Interestingly,the Indian plate kept on moving northward more than 50 Ma after the collision between the Indian and Eurasian continents and the break-off of the subducted oceanic slab attached to it.This strongly suggests that slab pull is not the main driving force of plate tectonics,whereas slab sliding is. 相似文献
826.
827.
GPS Solutions - The Hatch–Melbourne–Wübbena (HMW) combination is a geometry-free and ionospheric-free (first-order) function that has been widely used for cycle slip detection and... 相似文献
828.
Spatial co‐location pattern mining aims to discover a collection of Boolean spatial features, which are frequently located in close geographic proximity to each other. Existing methods for identifying spatial co‐location patterns usually require users to specify two thresholds, i.e. the prevalence threshold for measuring the prevalence of candidate co‐location patterns and distance threshold to search the spatial co‐location patterns. However, these two thresholds are difficult to determine in practice, and improper thresholds may lead to the misidentification of useful patterns and the incorrect reporting of meaningless patterns. The multi‐scale approach proposed in this study overcomes this limitation. Initially, the prevalence of candidate co‐location patterns is measured statistically by using a significance test, and a non‐parametric model is developed to construct the null distribution of features with the consideration of spatial auto‐correlation. Next, the spatial co‐location patterns are explored at multi‐scales instead of single scale (or distance threshold) discovery. The validity of the co‐location patterns is evaluated based on the concept of lifetime. Experiments on both synthetic and ecological datasets show that spatial co‐location patterns are discovered correctly and completely by using the proposed method; on the other hand, the subjectivity in discovery of spatial co‐location patterns is reduced significantly. 相似文献
829.
ABSTRACTBased on a large-scale household survey conducted in six large Chinese cities, this study is among the first attempts to juxtapose factors related to institution, market, and demography to examine the complex patterns and mechanisms of housing differentiation and housing poverty in low-income neighborhoods, which are conventionally conceived as homogenous substandard settlements. Results of Theil indices and multivariate regression models convey several interesting findings. First, the forces of the market and the State have projected different impacts on various aspects of housing status. Institutional factors had significant impacts on some costly and durable housing indicators such as housing tenure and housing area, while market forces have swiftly transformed the most malleable aspects of housing conditions, such as housing facilities, and will eventually replace some institutional legacies. Second, within-group housing differentiation is more palpable than between-group housing differentiation, suggesting that low-income neighborhoods in large Chinese cities are fluid and heterogeneous. Third, different institutional elements have different impacts on housing poverty. The well-functioning market remuneration system helps reduce the risk of housing poverty, yet working poor remains a severe problem. These findings can inform policies promoting social mix and housing affordability. 相似文献
830.
民族文化资源的类型特征及成因分析——以格萨尔(果洛)文化生态保护实验区为例 总被引:2,自引:1,他引:1
由人类非物质文化遗产《格萨(斯)尔》史诗派生出的格萨尔文化是青藏高原地区独特的区域文化形态。文化资源是文化的载体和展示形式,具有价值性和不可替代性。研究格萨尔文化资源的分类、空间分布及成因对于探讨青藏高原地区人地关系,保护人类非物质遗产有非常重要的意义。果洛藏族自治州是格萨尔文化资源最为富集的区域,并于2014年被授予格萨尔文化生态保护实验区。本文首先对格萨尔文化资源进行界定和分类,并以果洛为例,探讨格萨尔文化资源的空间分布特征及与自然地理条件(高程、水源、坡度、坡向、可达性)的关系,并分析影响文化资源分布的原因,得出以下结论:① 格萨尔文化资源可以分为4大类,11个亚类和60个子类,果洛的格萨尔文化资源覆盖全部类型,共1189个;② 果洛格萨尔文化资源空间分布具有聚集性,其中A类文化人(团体)类集聚程度最高,并通过最近邻分析和密度分析对各类文化资源的集聚空间进行识别;③ 格萨尔文化资源的空间分布与自然地理条件有关,多位于海拔相对较低、距水源地较近的位置,不同类型的文化资源分布对坡度、坡向和可达性的关系不同。 相似文献