Search

Abstract: 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 socio-economic 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 10years. 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. [Copyright &y& Elsevier]

Abstract: This paper describes the development of a forecasting model, named the emergy-based urban dynamic model capable of accurately simulating the observed resource consumption, economic growth and environmental impact of Beijing. This model differs from previous urban emergy models by monitoring the negative effects to human well-being and ecosystem integrity in the developing urban system. A fresh perspective focuses on urban comprehensive performance linking such impacts to a supply-side environmental cost evaluation (including ecological service supply, ecological and economic losses and investment for treatment). In this introductory paper, we present the conceptual considerations of the most important components of the emergy-based urban dynamic model: the urban assets, lands, capitals, population, water resources, economic and environmental loss. Each subsystem in this model will enrich the feedback dynamics, policy levers and post-scenario analyses. Statistical Information and calibration are also considered in this dynamic emergy accounting. This study advances the temporal dynamic principles of emergy accounting through integrating upstream and downstream evaluation methods to quantify the environmental impact by addressing specific damages to human health and ecosystem''s integrity and by linking such impacts to a supply-side environmental cost evaluation. [Copyright &y& Elsevier]

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 socio-economic 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 economic processes oriented to sustainable urban development. Taking Beijing city as the case, the network accounting and related ecological evaluation of a practical urban economy are carried out in this study in the light of flux, efficiency, utility and structure analysis. The results showed that a large quantity of energy and resources have to be consumed to maintain the structure and function of a city. The thermodynamic efficiencies of individual sector in Beijing remain at a low level. The social system in Beijing is a highly competitive network, and there are 8 competitive relations and only two mutualistic ones. The Domestic and Agricultural sector are the major controlling factors of the system. Moreover, the assessment results of Beijing are compared with the other three socio-economic systems, Norway, UK and Italy, and the ecological network function and structure comparisons are correspondingly illuminated and discussed. The conclusions indicate that the exergy-based network analysis can be refined to become an integrative tool for evaluation, policy-making and regulation for urban socio-economic system management concerning structure and efficiency at urban levels. [Copyright &y& Elsevier]