Study on Spatial Structure Identification of Urban Agglomeration in Central Yunnan Province Based on Fractal Theory

Author(s):  
Wenzheng Yang ◽  
Jiashen Ma ◽  
Yujun Pan ◽  
Meilin Li
2020 ◽  
Vol 12 (18) ◽  
pp. 7550
Author(s):  
Jiao Li ◽  
Yongsheng Qian ◽  
Junwei Zeng ◽  
Fan Yin ◽  
Leipeng Zhu ◽  
...  

By shortening the transportation time between cities, high-speed rail shortens the spatial distance between cities and exerts a far-reaching influence on urban agglomerations’ spatial structures. In order to explore the influence of high-speed rail on the spatial reconstruction of an urban agglomeration in western China, this paper employs fractal theory to compare and analyze the spatial structure evolution of the Chengdu–Chongqing urban agglomeration in western China before and after the opening of a high-speed railway. The results show that after the completion of the high-speed railway, the intercity accessibility is improved. The Chengdu–Chongqing urban agglomeration’s spatial distribution shows a decreasing density from the central city to the surrounding areas. Furthermore, the urban system presents a trend of an agglomeration distribution. Therefore, strengthening the construction of high-speed rail channels between primary and medium-sized cities, as well as accelerating the construction of intercity railway networks and rapid transportation systems based on high-speed rail cities, would help develop urban agglomerations in western China.


2021 ◽  
Author(s):  
Yue Huang ◽  
Ruiwen Liao

Abstract The green economy has gained worldwide attention, especially in the urban agglomerations where population and economic activities are highly concentrated. However, what kind of urban agglomeration spatial structure is more conducive to promoting the green economy? No clear conclusions have been made. Here, we study the impact of urban agglomeration spatial structure on the green economy, and also reveal how urban agglomeration spatial structure influences the three subsystems of green economy. We find that: (1) urban agglomeration spatial structural evolution is closely related to green economy, while in the research period, most urban agglomerations are not located in the optimal range of the spatial structure that drives the green economy. (2) Towards polycentric spatial structure is contributive to green economic growth, however, the excessively polycentric could not benefit green economy. (3) The evolution of urban agglomeration spatial structure exerts heterogenous impacts on the three subsystems when green economy is decomposed into economic subsystem, resources subsystem, and environmental subsystem. Towards polycentric is more conducive to the improvement of economic subsystem and resource subsystem, while, the tendency to monocentric drives the environmental subsystem development. (4) Lastly, our conclusions enlighten the urban agglomeration development planning and spatial mode for approaching a better performance in green economy.


2020 ◽  
Vol 12 (17) ◽  
pp. 7230
Author(s):  
Zhengfa Chen ◽  
Dongmei Shi

As an important part of farmland, the slope farmland is widely distributed in the central and western plateau mountain region in China. It is necessary to scientifically evaluate the slope farmland quality (SFQ) and analyze the spatial structure characteristics of SFQ to ensure reasonable utilization and partition protection of slope farmland resources. This paper takes the typical plateau mountain region—Yunnan Province in China—as an example and systematically identifies the leading factors of SFQ. The sloping integrated fertility index (SIFI) is adopted to reflect the SFQ. The evaluation system is built to quantitatively evaluate the SFQ and the spatial structure characteristics of SFQ were analyzed by a geostatistical model, autocorrelation analysis and spatial cold–hot spot analysis. The results show that the SFQ indexes in Yunnan Province are between 0.36 and 0.81, with a mean of 0.59. The SFQ grade is based on sixth-class, fifth-class, seventh-class and fourth-class land. The SFQ indexes present a normal spatial distribution, and the Gaussian model fits well with the semi-variance function of the spatial distribution of SFQ indexes. Furthermore, the spatial distribution of SFQ indexes is moderately autocorrelated. The structural factors play a major role in the spatial heterogeneity of SFQ indexes, but the influence of random factors should not be ignored. The spatial distribution of SFQ grades has a significant spatial aggregation characteristic, and the types of local indicators of spatial association (LISA) are based on high–high (HH) aggregation and low–low (LL) aggregation. The cold spot and hot spot distributions of SFQ grades display the significant spatial difference. The hot spot area is mainly distributed in Central Yunnan and the Southern Fringe, while the cold spot area mainly distributes in the Northeastern Yunnan, Northwestern Yunnan and Southwestern Yunnan. This study could provide a scientific basis for SFQ management and ecological environment protection in the plateau mountain region.


2019 ◽  
Vol 23 (3) ◽  
pp. 191-198
Author(s):  
Penghui Luo ◽  
Shitao Zhang ◽  
Yimin Tian ◽  
Fei Ding ◽  
Zongming Xu

The column height of earth forest is generally 8~30m in yuanmou county of yunnan province, which is far higher than the self-supporting height of general soil column. Ferruginous cement is an important reason for formation of the tall and erect columnar soil. Macroscopic physical and mechanical tests confirmed that the strength of the stratum containing ferruginous cement was much higher than that of the formation without ferruginous cement. The microstructure and morphology of ferruginous cement were analyzed by SEM and EDS. It is found that ferruginous cement is mainly composed of iron compounds and clay minerals, which only exists in certain stratum. In the process of growth, Iron compounds chemically bond with clay minerals during growth to form ferruginous cements, which first form unique sphere on the surface of particles or clay minerals. It then clumps together and fills the spaces between the particles. Finally, the dispersed particles are connected together to form a stable lamellar spatial structure, which greatly improves the strength of the soil. Through the study of ferruginous cement, the mechanism of this natural curing agent is understood, which enriches the research content in this field.


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