The structure, evolution and sustainability of urban socio-economic system

a r t i c l e i n f o Keywords: Ecological network analysis Extended exergy analysis Structure Utility Urban ecological economic system Analyzing the structure and functioning of the urban system revealed ways to optimize its structure by adjusting the relationships among compartments, thereby demonstrating how ecological network analysis can be used in urban system research. Based on the account of the extended exergy utilization in the sector of urban socioeconomic system, which is considered as the composition of extraction (Ex), conversion (Co), agriculture (Ag), industry (In), transportation (Tr), tertiary (Te) and households (Do) sectors, an urban ecological network model is constructed to gain insights into the sustainable urban development process. Taking Beijing city as a model case, the network accounting and related ecological evaluation of a practical urban economy are carried out in this study in the light of flux, utility and structure analysis. The results showed Beijing had made some progress in moving manufacturing economy into service economy during the 10 years. The increased output of the domestic sector (labor services) relieves the energy demand being placed on agricultural, industrial, transportation and tertiary sectors. The transportation sector was becoming a controlling factor to fluctuate the other sectors and the cross-regional trade is beginning to overshadow the crucial role of local manufacturing, which is due partly to the restructuring of the Beijing's commodity markets since the 1990s. The major implication of our work is that the exergy-based network analysis can be refined to become an integrative tool for evaluation, policy-making and regulation for ecosystem management concerning structure and efficiency at urban levels. Following the ecological metaphor, urban socioeconomic system represents a type of agglomeration economy (Ashton, 2008), which will benefit from knowledge of how ecosystems function under exploited conditions (Patten, 2010). The sustainable urban ecosystem would be expected to evolve based on the maintenance of healthy natural ecosystem functions, economic opportunities and desirable interactions among urban sectors with each other and the environment. In order to achieve these goals, a location-specific understanding of socioeconomic subsector's interactions is necessary (Fath, 2006; Fath et al., 2008; Zhang et al., 2010a,b). Since the mid-1980s, a lot of experts and scholars have carried out thorough and meticulous researches into the urban socioeconomic operation. However, the main urban study fields have been focused on the fluxes of single elements and on 'nutri-tion' with respect to that corresponding element, while the analysis of …