Lishan Xiao

Effects of spatial form on urban commute for major cities in China

The global phenomenon of urbanization increases the importance of compact-city development. China’s rapid urban development has resulted in unprecedented urban population growth and built-up area expansion, but its effects on urban morphology and mobility are only partly understood. City compactness can be measured simply using urban spatial form or morphology: the more concentrated the built-up area, the more compact the city is. Here we show that 35 major cities in China are not compact in spatial form and that their compactness is not improving over time. Our results reveal close correlations between changes in urbanization rate and changes in city compactness as well as between city compactness and commuting time (CT), indicating that the high rate of urbanization without adequate planning has contributed to the poor compactness of Chinese cities, which has further increased CT. We suggest that continuing urban sprawl with low land use efficiency and low urban form compactness will make cities in China more congested and threaten China’s sustainable urbanization.

Integrating climate change adaptation and mitigation into sustainable development planning for Lijiang City

Cities are facing considerable challenges resulting from imminent climate change impacts. Urban planning to minimise adverse impacts of climate change at the city level can establish a climate-resilient city. Mitigation strategies to reduce CO2 emissions would lead to a climate-friendly city. Integrating climate change adaptation and mitigation into sustainable city planning should not be merely added as a single level of sustainable city planning, but requires a wide range of multi-level cooperation. Lijiang City has experienced climatic change during the last half century, and its CO2 emissions have increased faster than the GDP growth. Nearby glaciers on Yulong Snow Mountain have been retreating and losing mass since the early twentieth century. In this paper, we identify economic sectors that are vulnerable to climate change, including tourism, agriculture and water supply, and propose mitigation and adaptation strategies to cope with climate change in this tourism city. As energy use is the largest source of greenhouse gas (GHG) emissions, renewable energy has enormous CO2 reduction potential. Land use practices, a sectoral approach and public participation are all considered adaptive in climate planning. The proposals outlined are valuable as they provide an understanding of how to implement integrated climate planning and integrate climate change mitigation and adaptation into sustainable city planning.

Household waste management for a peri-urban area based on analysing greenhouse gas emissions for Jimei District, Xiamen, China

This study aims to find the generation characteristics of household waste (HW) in a peri-urban area and establish an optimal HW management system to improve inhabitants living environment and for energy saving and pollution abatement. Jimei District, Xiamen, was chosen as a case study and 10 representative communities were selected as study areas. Questionnaires and a field survey were applied to investigate the characteristics of peri-urban area HW generation. After combining the results for communities of different urbanisation levels, representative communities were classified into three groups. Greenhouse gas (GHG) emissions from the current HW management system and a proposed integrated management system were compared. The results show that the integrated HW management system would achieve greater energy savings and GHG mitigation. Emissions from HW management in the lowest urbanised communities remained highest. However, the relationship between emissions and community urbanisation level was not completely linear. Finally, three kinds of integrated management strategy for HW generated from different community groups are proposed and suggestions given to establish an optimal integrated HW management system for peri-urban areas.

Characterizing Urban Household Waste Generation and Metabolism Considering Community Stratification in a Rapid Urbanizing Area of China.

The relationship between social stratification and municipal solid waste generation remains uncertain under current rapid urbanization. Based on a multi-object spatial sampling technique, we selected 191 households in a rapidly urbanizing area of Xiamen, China. The selected communities were classified into three types: work-unit, transitional, and commercial communities in the context of housing policy reform in China. Field survey data were used to characterize household waste generation patterns considering community stratification. Our results revealed a disparity in waste generation profiles among different households. The three community types differed with respect to family income, living area, religious affiliation, and homeowner occupation. Income, family structure, and lifestyle caused significant differences in waste generation among work-unit, transitional, and commercial communities, respectively. Urban waste generation patterns are expected to evolve due to accelerating urbanization and associated community transition. A multi-scale integrated analysis of societal and ecosystem metabolism approach was applied to waste metabolism linking it to particular socioeconomic conditions that influence material flows and their evolution. Waste metabolism, both pace and density, was highest for family structure driven patterns, followed by lifestyle and income driven. The results will guide community-specific management policies in rapidly urbanizing areas.

Analysis of socio-economic driving forces on built-up area expansion in Xiamen

Based on grey relational analysis and stepwise regression, this study analysed the socio-economic driving forces of Xiamen since the reform and opening of China. The research aimed to explore the deep dynamic mechanism of urban space expansion of Xiamen and provide scientific support for its sustainable development. The results indicate resource consumption factors and population factors have had a significant driving effect on the expansion of built-up area, and have contributed more than the economic development factors. It was revealed that the main urban socio-economic driving forces have gradually changed during the middle and late stage of urbanisation, and the city has also shifted from an original construction and developing city type into a more spatially stable, developed city type.

Spatial restructuring and land consolidation of urban-rural settlement in mountainous areas based on ecological niche perspective

With the socio-economic development associated with urbanization, the urban-rural relationship has changed across the world. In China, due to the urban-rural dual structure, these changes turn out to be more complicated. Spatial restructuring are suggested as the main strategies and spatial supporting platforms for urban-rural development. However, the theory still lacks solid methodology and support from systematic empirical studies. This study seeks an adequate scientific methodology and discusses the difference of urban-rural transformation in plains and mountainous areas. A case in Shanghang County, China, demonstrates: 1) The compound ecological niche model can be a suitable approach in urban-rural restructuring, especially in mountainous areas. 2) The urban-rural development area with highly inappropriate, slightly appropriate, moderately appropriate, and highly appropriate areas are 1273.2 km2 (44.69%); 906.1 km2 (31.80%); 509.4 km2 (17.88%); and 160.1 km2 (5.62%), respectively. 3) The “deserting villages” in mountainous areas play positive synergistic roles in urbanization, in contrast to the “hollowing villages” common in plain areas. 4) The central town-village will become the most important settlement in mountainous areas. Therefore, we suggest more attention should be paid to environmental capacity in the construction of central town-villages. This study significantly extends the understanding of “hollowing village” theory and regional planning.

Understanding urban–rural linkages from an ecological perspective

ABSTRACT Urban–rural linkages, which inevitably evolve over time, are influenced by economic, geographic, and demographic factors. In this paper, emergy accounting was used to calculate sustainability indicators and examine the metabolic processes that connect natural environments and rural–urban systems. A map of energy and material flow was visualized with a Sankey diagram, and urban–rural linkages were quantified according to ecological networks. Both rural and urban areas had open metabolic cycles, but the rural system was more dependent on the natural environment and showed better environmental performance. Urban–rural linkages reflected economic transformations during urbanization and formed a complex web of connections. The rural area’s economy and social system were unique in that they were not traditionally self-sufficient. Both rural and urban systems exploited the natural environment. From an ecological perspective, a competitive relationship exists between rural and urban systems, which may result in resource conflict and weaken the sustainability of urban and rural areas. The modern urban–rural linkage indicates a new trans-territorial type of rural system, the town village, which is an emerging phenomenon unique to China and imposes household registration systems. Urbanization has reshaped urban–rural linkages, and thereby influenced system sustainability. The results suggest that new resource management policies should be developed to coordinate the relationship between China’s urban and rural systems during urbanization.

Characterization of the quenching process and the protection of an ac high temperature superconductor coil

Publisher Summary This chapter introduces a two-step model of the quenching in the HTS coil. Experimental characterization and numerical simulation of the quenching process in a test high temperature superconductor (HTS) coil are made. A thermal runaway quench only occurs after the cooling rate is exceeded by the heating rate. In ac cases, the competition of cooling and heating is in principle the same except that the coil is heated up continuously by the ac loss as long as I w is applied. The heat accumulation comes from ac losses and current sharing is attributed for the quenching development in the coil. The effective critical current of the coil decreases with the temperature increasing. This enhances both the ac loss and the current sharing effect. Consequently, the first step of quenching will occur within a second. Detecting this and making a quick response are important for protecting the ac coil. According to the modeling and the experimental results, a possible method to detect the first step of quenching is developed, which can be helpful in the power usage of the ac HTS coils.