Chengliang Liu

Spatial heterogeneity of ports in the global maritime network detected by weighted ego network analysis

ABSTRACT More extensive attention has been paid to the heterogeneity of maritime transport network in topological rather than in spatial aspects. However, the importance of links and the roles of neighbors of a node has been ignored if not all. To fill this gap, this article introduced the approach of weighted ego network analysis (WENA) to visualize the spatial heterogeneity of the maritime network at global and local levels. The topological connectivity graph of the global marine network was derived, and its structural properties were analyzed. It is found out that the values of the degree of ports follow power-law distribution, which indicates that the global marine network is scale-free, that is, there are few well-connected ports and a majority of less connected ports. The spatial disparities of the network can be described by a core–periphery pattern. In global, most of the hubs or ports with extremely high values of degree locate in the big-three maritime regions including Far East, North America, and West Europe. Along the peripheral belts of the three regions, there are lots of less connected small ports. A different hierarchical structure of six continents was captured by WENA. It is found that Europe, Asia, North America, and Africa showcase a pyramid-shaped hierarchical structure with a scale-free feature similar to the entire network, while South America and Oceania exhibit the fusiform hierarchy like small-world networks. It is proposed that such spatial inequality and heterogeneity were caused by the geographical environments such as the hub-and-spoke organization, the embedded trade pattern, and the proximity of location. These findings help us to understand the characteristics of the international trade pattern and shed light on the strategies of development for the industry stakeholders.

Mapping intellectual structures and dynamics of transport geography research: a scientometric overview from 1982 to 2014

To date, less care has been taken to quantitatively visualize the intellectual evolution of transport geography research than to qualitatively review this field. Based on big-data literature from the Thomson Reuters Web of Science as well as scientometric mapping analysis, this important research topic is analyzed by techniques from informetric domains to detect its developmental landscape. After data reduction and clean-up, 4840 articles published from 1982 to 2014 are identified on which two network analyses are conducted: a bibliometric approach (i.e. co-occurrence and co-citation network) and a complex network approach utilizing C. Chen’s CiteSpaceII, O. Persson’s BibExcel and ESRI’s ArcGIS. Results illustrate the following: (1) periods including the rise (1960–1970s), to a stagnation period (1980–1990s), to a boom (since 1990); (2) that the change of research frontiers and hot issues is either social oriented or topic oriented; (3) that its development owes a good deal to cooperative subnetworks (schools) of six academic communities—Urban Planning, Marxist Geography, Mobility Turn, New Economic Geography, Port Geography, and Time Geography; and (4) that its research methods tend to be diversified and integrated, while its research perspective is inclined to be microcosmic and oriented to social hot issues. Finally, 23 documents are identified as playing the pivotal role in its knowledge evolution as an intellectual base.

Identifying and mapping local contributions of carbon emissions from urban motor and metro transports: A weighted multiproxy allocating approach

Regional allocation of transport carbon emissions is increasingly important to meet global or national CO2 reduction targets. Limited by scaling and data uncertainties, geographical allocation of carbon-emitting responsibilities or burdens at local or fine scales has not been well documented. In this regard, after estimating total carbon emissions from urban motor and metro transports, we proposed a multiproxy allocation system that included a series of transport-related demand and supply indicators. On the basis of urban high-resolution data, magnitudes of gridded proxies in fine scales were aggregated into each local administrative region (subdistrict and town) by a bottom-up approach. Then, weights of these indicators were calculated through an integration of Grey Relational Analysis with Fuzzy Logic. Finally, using the practical scenario of Wuhan (China), we allocated total carbon-emitting quantities from the Wuhan metropolis down to local units by using a top-down approach. Local carbon-emitting contributions and their variations were further identified and mapped from total, per capita, and per unit perspectives. We have not only shown this allocative approach to be effective and applicable, but have also depicted spatially similar patterns and evolutions under the three carbon-emitting indicators. These depictions include local inequality and polarization, core-peripheral structure, place-dependence on initial location, and spatial locking-in effect and diffusive trends along metro lines. Additionally, spatial differences between the per capita carbon emission and the others are revealed as well.

Relationships between fractal road and drainage networks in Wuling mountainous area: Another symmetric understanding of human-environment relations

Symmetrical relationships between humans and their environment have been referred to as an extension of symmetries in the human geographical system and have drawn great attention. This paper explored the symmetry between physical and human systems through fractal analysis of the road and drainage networks in Wuling mountainous area. We found that both the road and drainage networks reflect weak clustering distributions. The evolution of the road network shared a significant self-organizing composition, while the drainage network showed obvious double fractal characteristics. The geometric fractal dimension of the road network was larger than that of the drainage network. In addition, when assigned a weight relating to hierarchy or length, neither the road network nor drainage network showed a fractal property. These findings indicated that the fractal evolution of the road network shared certain similarities with fractal distribution of the drainage network. The symmetry between the two systems resulted from an interactive process of destroying symmetry at the lower order and reconstructing symmetry at the higher order. The relationships between the fractal dimensions of the rural-urban road network, the drainage network and the urban system indicated that the development of this area was to achieve the symmetrical isomorphism of physical-human geographical systems.

Allocating and mapping carbon footprint at the township scale by correlating industry sectors to land uses

Abstract A key part of reducing 2 emissions is exploring scientific methods for calculating carbon footprints and allocating their sources. Several limitations in current approaches exist at smaller scales due to shortcomings and uncertainty in data collection. This article implements an improved approach to allocate carbon footprints at the local, neighborhood scale, taking land uses as a criteria, after verifying the correlation between industry sectors and land uses through cointegration test. A case study of the Wuhan Metropolitan Area (Wh) is provided to examine the methods applicability and effectiveness. Some related spatiotemporal variations in carbon‐footprint values at the township scale are depicted as a spatial tendency from zonal agglomeration to radial diffusion in a core‐periphery structure, which relates to such human‐driven factors as population, transportation, and urban (built‐up) area. The findings provide insight for policymakers to generate appropriate allocative strategies for low‐carbon development.

Mapping the hierarchical structure of the global shipping network by weighted ego network analysis

An improved complex network approach named weighted ego network analysis (WENA) was employed to explore the hierarchical structure of the global shipping network. First, it was found that all centrality indices exhibited scale-free properties with obvious power-law distributions. That is, less than 30% of shipping ports had quite high centrality values, which are powerful hubs of the global shipping system. Those very accessible shipping ports showed significant preferential attachment properties such as rich-club and Matthew effect. Second, results of WENA revealed its core-peripheral hierarchical structure, which could be divided into five levels of sub-networks: first tier (top 5%), second tier (top 5%~15%), third tier (top 15%~30%), fourth tier (top 30%~50%), and fifth tier (the remainder). Finally, five kinds of correlation analyses have been carried out, including degree vs. degree, degree vs. strength, degree vs. clustering coefficient, degree vs. distance and centrality vs. GDP. Results indicated that the connectivity of a shipping port was both significantly influenced by the connectivity of its directly connected ports, the shipping distance and hinterland economic scale.

Twenty-five years of progress in geopolitics research: Efforts from China’s geographers

The world is currently undergoing profound changes, with a shift in global power centers and reordering of international power spaces, assigning new theoretical tasks as well as providing new opportunities for geopolitics research in China. Despite the peripheral nature of geopolitics research within their discipline, geographers have played a fundamental role in its origins and revival, from classical geopolitics (i.e., the German school of geopolitics and the Anglo-American school of geo-strategy), to internal geopolitics (i.e., electoral geography and administrative geography), to the new geopolitics (i.e., formal geopolitics), and to recent critical geopolitics (i.e., popular geopolitics). Although only few of these researchers were from China, great strides have been made in geopolitics and political geography research in China, with useful results being obtained. After demonstrating the importance of geopolitics research for the rising China, this review provides an overview of geopolitics papers led by China’s geographers in the past few decades, describing their achievements, the problems they have faced, and the directions they have taken. Twenty-five years of geopolitics have produced a range of accomplishments, with a growth in the quality and size of research groups and institutions, an expanding literature, and some geo-strategic break-throughs. Obviously, geographers have successfully reclaimed geopolitics, but some crucial topics are still absent or weak in the geopolitical research agenda, and need to be pursued vigorously. Most of the attention, from a positivistic perspective, has been paid to reflecting Western geopolitical thoughts, describing patterns of international power relations, and offering foreign policy advice (in a problem-focused orientation), rather than determining mechanisms and performing theoretical analyses (in a theoretical orientation), resulting in a lack of independent value judgments and of a theoretical basis for the subject. Moreover, in comparison with other disciplines, in terms of its academic community, research output, and status as a discipline, geopolitics research is very different from how it was three or four decades ago, when it was mainly the property of geographers, rather than political scientists and diplomats. For now, whether to support national geo-strategies or to enhance the diversity of the discipline, the involvement of geographers in geopolitics needs to become both more intensive and more extensive. The top priority is to strengthen theoretical, methodological, and problem- oriented research, including studies of geopolitical philosophy and methodology, the theoretical framework of the subject, global geopolitical evolution and shifts in power space, the roles of major powers and their geo-strategies, as well as China’s surrounding geopolitical environment.