Research on the synergy of urban system operation-Based on the perspective of urban metabolism

Urban resilience under the COVID-19 pandemic: A quantitative assessment framework based on system dynamics

The COVID-19 pandemic, which lasted for three years, has had a great impact on the public health system, society and economy of cities, revealing the insufficiency of urban resilience under large-scale public health events (PHEs). Given that a city is a networked and multidimensional system with complex interactions, it is helpful to improve urban resilience under PHEs based on system thinking. Therefore, this paper proposes a dynamic and systematic urban resilience framework that incorporates four subsystems (governance, infrastructures, socioeconomy and energy-material flows). The composite index, system dynamics and epidemic simulation model are integrated into the framework to show the nonlinear relationships in the urban system and reflect the changing trend of urban resilience under PHEs. Then, urban resilience under different epidemic scenarios and response policy scenarios is calculated and discussed to provide some suggestions for decision-makers when faced with the trade-off between the control of PHEs and the maintenance of city operation. The paper concludes that control policies could be adjusted according to the characteristics of PHEs; strict control policies under a severe epidemic could lead to a significant decrease in urban resilience, while a more flexible control strategy can be adopted under a mild epidemic scenario to ensure the normal operation of urban functions. Moreover, the critical functions and impact factors of each subsystem are identified.

Water-carbon nexus relationship and interaction mechanism analysis within Beijing-Tianjin-Hebei urban agglomeration

As the total water resources consumption control and carbon mitigation continuous improvement, the weak water-carbon incorporate management is increasingly exposed. In this study, a water-carbon nexus assessment framework is proposed to analyze the nexus relationship between water consumption and carbon emission, and distinguishes the coupled water-carbon transmission intensity and the transfer paths under regional and industrial scales. According to the practical input-output table, water consumption, and carbon emission information, the framework is applied to Beijing-Tianjin-Hebei urban agglomeration (BTHUA), a population, resource, and trade intensive area of China. Inter-regional/intra-regional water consumption and carbon emission transfer fluxes between sectors, the pairwise ecological relationship, and the water-carbon nexus were analyzed. Results indicated that the water-carbon transfer indexes from Hebei to Beijing and Tianjin were 161.85 kg/m³ and 113.88 kg/m³ in the study period, along with the most water consumption and carbon emission, and the worst water-carbon nexus. From the industrial perspective, electricity and gas supplying industry provided 7.8% and 29.1% of the total carbon transfer in Tianjin and Hebei, as the most key node sectors on the water-carbon nexus in the BTHUA. The research provides valuably supporting the adjustment of the existing urban agglomeration water-carbon nexus management schemes.

Exploring the raison d'etre behind metric selection in network analysis: a systematic review

Network analysis is a useful tool to analyse the interactions and structure of graphs that represent the relationships among entities, such as sectors within an urban system. Connecting entities in this way is vital in understanding the complexity of the modern world, and how to navigate these complexities during an event. However, the field of network analysis has grown rapidly since the 1970s to produce a vast array of available metrics that describe different graph properties. This diversity allows network analysis to be applied across myriad research domains and contexts, however widespread applications have produced polysemic metrics. Challenges arise in identifying which method of network analysis to adopt, which metrics to choose, and how many are suitable. This paper undertakes a structured review of literature to provide clarity on raison d'etre behind metric selection and suggests a way forward for applied network analysis. It is essential that future studies explicitly report the rationale behind metric choice and describe how the mathematics relates to target concepts and themes. An exploratory metric analysis is an important step in identifying the most important metrics and understanding redundant ones. Finally, where applicable, one should select an optimal number of metrics that describe the network both locally and globally, so as to understand the interactions and structure as holistically as possible.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s41109-022-00476-w.

Regional industrial synergy: Potential and path crossing the "environmental mountain"

Regional cooperation and common development are the new normal strategies of regional sustainable development and important approaches that positively affect economic globalization. Breaking the "small island thinking" model of a region or a country that only relies on "self-development" in economic development, exploring new kinetic energy for regional economic growth, and tapping the new potential of coupling development of economy and environment are important tasks to promote regional coordinated development. Benefits of regional industrial synergy in terms of economic growth, energy conservation, and consumption reduction are discussed on the basis of the synergetic development of regional industries as the entry point. Modified spatial gravity model, location quotient (LQ), LQ ratio (LQR), Krugman regional division index, industrial structure similarity coefficient (S), time series analysis, and scenario analysis are applied. In addition, the "Xia-Zhang-Quan" Metropolitan Area is considered as a case. Results show that: (1) the three industrial development of Xiamen, Quanzhou, and Zhangzhou has evident gradient structure, but the industrial structure has serious isomorphism (S_xq = 0.94, S_xz = 0.96, S_qz = 0.98); (2) Xiamen and Zhangzhou can achieve synergetic development through intra-industry and industrial chain division (LQR_xz = 1.214), and Xiamen and Quanzhou can further cooperate on inter-industry division (LQR_xq = 0.566); (3) In 2025, compared with the unadjusted mode, the "Xia-Zhang-Quan" Metropolitan Area can achieve 35.21% of economic growth space and reduce energy consumption by 32.85% under the synergetic mode. Therefore, regional industrial synergy can not only release great economic growth potential, but also has important potential in promoting regional development to cross the "environmental mountain". This study aims to explore an effective regional synergetic development path and new driving forces to promote developing countries, especially China, to cross the "environmental mountain" and realize the coupling development of social economy, resources, and environment.

Environmentally-extended input-output and ecological network analysis for Energy-Water-CO2 metabolic system in China

Resource and environmental elements as controlling factors for ecologic and socio-economic are crucial to seek new ideas and paths for development and prosperity. In this study, environmentally-extended input-output analysis and ecological network analysis were combined to develop three ecological networks including energy ecological network, water ecological network, and carbon ecological network for searching the complex relationships among different departments for water utilization, energy consumption, and carbon emissions under considering China as a superorganism with various complex metabolic processes and the most fundamental metabolic materials. The embodied ecological elements intensity, the indirect consumption and emissions, the embodied material flows, the ecological relationships, and the dependence intensities among sectors was obtained through transforming the monetary input-output data to physical data from 2007, 2012, and 2017. The results show that the Energy Ecological Network and Water Ecological Network were in a relatively stable state with a mutualism index greater than 1, and the relationship among different sectors in the CO₂ Ecological Network needs to be further adjusted. AM (Advanced Manufacture) and Agr (Agriculture) played the top exporter and importer roles with AM as the largest embodied energy consumer and CO₂ emitter, and Agr as the largest embodied water user. More measures about resource conservation and emission reduction for AM and Agr are desired. Con (construction) had a strong dependence intensity on other sectors with amounts of over 90%. Resources and environmental effects on Con can be improved by increasing the utilization efficiency of intermediate products. The results could provide scientific policy implications and guidelines to promote the stable and healthy operations by revealing the dynamic change of sectors within the Energy-Water-CO₂ metabolic system in China.

Urban biocycles - Closing metabolic loops for resilient and regenerative ecosystem: A perspective

Cities are at crossroads, confronting challenges posed by increasing population growth, climate change and faltering livability. These problems are prompting urban areas to chart novel path towards adopting sustainable production/consumption strategies. The alluring concept of circular economy (CE) that focuses on reuse and recycling of materials in technical and biological cycles to reduce waste generation is a critical intervention. Present article aims on precisely highlighting the importance of biogenic materials which have an immense potential to be transformed into a source of value in an urban ecosystem. It also sets out to explore the scope of implementing 'urban biocycles' that strategically directs the flow of resources, their use, extracting value in the form of nutrients, energy and materials post consumption within an urban metabolic regime. The concepts discussed contribute to biocycle economy by outlining emerging requirements, identification of common strategies, policies and emerging areas of research in line with sustainable development goals.