Large-sized Cities Research Articles

Promoting coordinated spatial governance of mega-cities in China via spatial organization of metropolitan areas

Super large-sized cities and very large-sized cities (“mega-cities” for short) have become the backbone of China's socio-economic development, but they also face outstanding challenges of "urban diseases" due to their high concentration. In comparison to their foreign counterparts, China's mega-cities possess unique characteristics such as rapid growth, high population density, and large numbers of residents. They naturally have the attributes of metropolitan areas due to an administrative management system of an urban system within city territory. Promoting coordinated spatial governance of mega-cities via spatial organization of metropolitan areas not only helps mega-cities better allocate resources at a larger scope and helps expedite the transformation of development patterns, but is also crucial for better implementing new-type urbanization strategies. In response to the issues in China’s previous research and practices related to mega-cities and metropolitan areas, leveraging the “Critical Technology for Spatial Optimization of Metropolitan Areas of City Clusters” of the national key R&D plan in the “14th Five-year Plan” period, we have employed a scientific approach that combines data and models to propose spatial governance strategies. These strategies encompass both the overall metropolitan area level and the cross-border regional level. Our primary focus lies in optimizing the spatial layout of the “three domains” – ecological space, production space, and living space, facilitating functional dispersal, enhancing spatial patterns, adjusting land use structures and spatial resource allocation, coordinating rail transit and the organization of functions along transit lines, and innovating service management for improvement of administrative efficiency. Through the implementation of these diverse measures, we aim to establish a comprehensive composite collaborative system.

Carbon-oriented energy system planning using forest carbon sink

More than 130 countries and regions have put forward various climate goals, which makes carbon-oriented energy system planning a heated topic. However, these planning studies do not consider the carbon fixation role played by forest carbon sinks (FCSs). To take advantage of the carbon fixation role of FCSs, this paper will develop a carbon-cycle integrated energy hub (CC-EH) model to quantify the economic advantages of FCSs in planning a zero-carbon energy system, where energy flow and carbon flow are both analyzed. A total planning and operating costs minimization with the constraints of CO2 emissions is proposed as a mixed integer nonlinear programming (MINLP) optimization model and the overall problem is solved based on commercial solver. The proposed model is validated by case studies on six medium to large-size cities in different geographical locations in China. Results indicate that the typical cities in China can fulfill their carbon-neutral commitments by 2060. Throughout the entire planning period, FCSs can offset up to 55.31 % of the total carbon dioxide emissions from urban energy systems. Besides, FCSs achieved by forestation will help the energy system to reduce up to 36 % of the planning cost compared to the case without using FCSs.

Impact of Industrial Intelligence on China’s Urban Land Green Utilization Efficiency

Against the backdrop of the fourth technological revolution, industrial intelligence (INDI) represented by industrial robots has rapidly developed. This evolution provides favorable opportunities for precise decision-making in pollution control and achieving China’s “dual carbon” goals. Previous studies have mainly discussed the economic effects of INDI from the perspective of the labor market. This study shifts its focus to examining the impact of INDI on the land green utilization efficiency (LGUE) in cities. Using the panel data of Chinese cities spanning 2009–2021, this study empirically tests the effect and transmission mechanism of INDI on LGUE. We find that urban INDI significantly enhances LGUE. In terms of its transmission mechanism, INDI drives improvements in urban LGUE through technological progress, energy structure optimization, and industrial structure upgrading. Urban infrastructure construction and financial agglomeration level can further strengthen the positive impact of INDI on LGUE. In addition, the improvement in LGUE due to INDI is more significant in non-resource-based and large-sized cities than resource-based and small and medium-sized cities. Therefore, each region should enhance the integration of intelligent technology with traditional industrial manufacturing. Doing so is essential to establish comprehensive assessment indicators that balance environmental protection and economic growth, strengthen regional information infrastructure construction, ensure steady financial flow, and support green development initiatives across regions.

The Demographic Profile of The Population in Small, Medium and Large-Sized Cities in Romania

The present study analyzes the demographic profile of the population by categories of urban localities, categories established according to the number of inhabitants, respectively very small, small, medium and large-sized cities. The main conclusions from this study would be that approximately 40% of the Romanian population lives in medium and large cities, the average age of the population in very small and small towns is lower than that in larger cities, the share of the population whose domicile coincides with residence is higher in smaller cities compared to larger ones, and the distribution of the main ethnicities highlights a slightly asymmetric territorial distribution within the Hungarian ethnic group (there are localities with very high percentages of this ethnic group) and a symmetrical distribution for the Romany ethnic group.

Environmental Regulation, Foreign Direct Investment, and Green Total Factor Productivity: An Empirical Test Based on Chinese City-Level Panel Data

Environmental regulation is a crucial tool for government intervention in the field of green technology innovation. It can boost an enterprise’s competitiveness and encourage green technology innovation, both of which have a major effect on luring foreign investment. This paper first systematically elaborates on the relationship between environmental regulation, foreign direct investment (FDI), and green total factor productivity (GTFP) and then combines panel data from Chinese cities to empirically test these relationships using various methods, such as the mediation effect model, two-stage least squares, and difference-in-differences method. The study found that environmental regulation significantly boosts FDI and GTFP. FDI helps to improve GTFP, and environmental regulation can impact GTFP indirectly through FDI. The way that FDI and environmental regulations affect GTFP demonstrates regional variation. Large cities with high economic growth gain more from environmental regulation. FDI has a stronger promotion effect on GTFP in medium- and small-sized cities than in large-sized cities, and it does not significantly impact GTFP in cities with high levels of economic development or in the eastern region.

Can spatial patterns mitigate the urban heat island effect? Evidence from German metropolitan regions

This study examines the efficacy of urban spatial patterns at alleviating the urban heat island (UHI) effect in Germany’s city regions ( Großstadtregionen) using multivariate and non-parametric regression methods. Urban spatial patterns are quantified using five landscape metrics that capture the spatial arrangement of urban footprints and greenspaces, along with a polycentricity index that measures the distribution of human activities. The results indicate that certain features of urban fabric, including fragmentation, mixed land use, and regular-shaped urban patches, have the potential to mitigate the UHI effect. Moreover, dispersing multiple smaller greenspaces throughout the urban area demonstrates a greater cooling effect compared to having a single large and more aggregated park. In addition, our analysis reveals that a doubling (100%) of the polycentricity degree corresponds to a significant decrease in both day- and night-time UHI effects, with reductions of 10.4% and 24.6%, respectively. This study confirms that polycentric development yields greater benefits in reducing urban heat for large-sized city regions compared to medium- and small-sized ones; and its effectiveness is mostly pronounced near urban center(s). These findings suggest that polycentric development represents an efficient and feasible strategy for urban thermal planning of large-sized city regions, surpassing other commonly discussed urban configurations, such as compact or dispersed urban development.

Contraceptive switch and abandonment among women using the pill, condoms and injectables in Brazil

Objective The aim of our study was to assess the covariates of contraceptive switching and abandonment among Brazilian women stratified by oral pills, condoms and injectables. Materials and Methods Women attending primary health care services in three Brazilian mid- to large-sized cities were interviewed face-to-face about their contraceptive practices (n = 2,051). Data were collected using a contraceptive calendar. Analysis included estimates using Kaplan-Meier multiple-decrement life-table probabilities and discrete-time hazards modelling of switching from a method to another or to no method. Results Among 3,280 segments of contraceptive use, we observed that five-year contraceptive switching rates ranged from 34.9% among injectable users to 56.1% among pill users. Of particular concern were the high discontinuation rates of abandonment, which ranged from 50.9% among injectable users to 77.4% among pill users. Covariates of method switching and abandonment varied by type of method, but age, race/ethnicity, religion and relationship status must be highlighted as key elements of discontinuation. Conclusion Contraceptive method switching and abandoning are frequent outcomes of contraceptive use. Understanding the factors that shape women’s decisions to continue or discontinue the use of a contraceptive method can help tailoring comprehensive contraceptive counselling that meet their expectations and reproductive needs when starting using a method.

Spatiotemporal monitoring of subtropical urban forests in mitigating air pollution: Policy implications for nature-based solutions

Air pollution remains a major global challenge in addressing environmental and health issues requiring continuous and immediate action. Nevertheless, the extensive adverse effects from atmospheric pollution are mainly experienced by communities and people in lower- and middle-income countries, such as the medium- and large-sized cities in Latin America including the coastal city of Guaruja in Brazil. Urban forests, as integral parts of the city landscape, play a crucial role in mitigating air pollution and should therefore be considered in environmental policies. This study aimed to evaluate the spatiotemporal concentrations of air pollutants using the biological monitoring method with Tillandsia usneoides L. to highlight the capacity of urban forests to act as nature-based solutions (NbS) in improving air quality and providing other ecosystem services. Based on the quantification of chemical indicators of vehicle emissions, scientifically recognized as traffic‐related elements (TREs) such as cadmium (Cd), Copper (Cu) and lead (Pb) in the biomonitoring samples, the results showed spatiotemporal variations in their concentrations. This finding demonstrates that urban fragments in the low-income settlement of the city exhibited higher values for TREs during the wet season. Cu values were the highest during the wet season in all study areas, underscoring the intensity of the light vehicle fleet. Forest fragments attenuated air pollution, highlighting their importance as features of environmental planning. The identification of atmospheric pollution hotspots in the territory guided the strategic implementation of NbS through tree planting, thus promoting a healthier environment with greater mitigation potential. This study is the first in Brazil to explore the spatiotemporal relationship between air pollution and urban forests in highly dense and low-income settlements providing quantitative indicators toward the benefits of NbS.

The ambient air quality standards, green innovation, and urban air quality: evidence from China

As China’s economy transitions, environmental issues have become a major concern. This study examines the impact of Ambient Air Quality Standards (AAQS) on urban air quality using panel data from 284 cities in China from 2006 to 2019. The study utilizes DID (Difference-in-Difference) models to analyze the regulatory effects of AAQS and its spatial spillover. Additionally, the serial multiple mediation models are constructed to investigate the role of green innovation. The findings reveal that the AAQS positively affects urban air quality, albeit with a notable “hysteresis effect.” Local implementation of AAQS worsens air quality in neighboring cities within a distance of 400 km, but beyond 400 km, the effect is reversed. Heterogeneity analysis shows that AAQS improves air quality in central cities, large-sized and medium-sized cities, cities with weak environmental governance, and resource-based cities. Mechanism tests suggest that AAQS may enhance urban air quality by promoting green innovation and optimizing industrial structure. Especially, either the energy-use effect or industrial-structure effect triggered by green innovation can contribute to the improvement of urban air quality.

Can digital economy improve employment structure?-Mediating effect based on a spatial Durbin model.

Based on the panel data of 283 prefecture-level cities in China from 2011 to 2019, this study constructed an index measurement system of digital economy, economic agglomeration, innovation and entrepreneurship, and employment structure. The index of digital economy was developed by entropy weight method, and the double-fixed spatial Durbin model was constructed based on the intermediary effect from the spatial perspective to determine the direct effect, indirect effect, and total effect of the digital economy, economic agglomeration degree, and innovation and entrepreneurship on employment structure. The results indicated a significant spatial correlation between the three aspects, i.e., digital economy can significantly optimize the employment structure, with an evident spillover effect. The mechanism analysis revealed that the level of innovation and entrepreneurship poses a stronger intermediary effect than the degree of economic agglomeration, and the digital economy in the eastern region directly impacts the urban employment structure; however, the influence of digital economy on the employment structure is significantly higher in small- and medium-sized cities than in large-sized cities.

Modelling the impact of urban form on daily mobility energy consumption using archetypal cities

Urban form is regularly identified as a potential key factor for reducing road traffic and the resulting energy consumption, but the nature of the link between mobility and urban form has been subject to considerable debate. This paper employs quantitative research methods to investigate the influence of urban form on daily mobility energy consumption. First, we used archetypal cities, representative of French large-sized cities, which allow us to isolate the impact of urban form and to have more generalised results. Second, we simulated daily mobility in those archetypal cities by using an individual-based daily mobility simulation model, Mobisim-Soft and then calculated the resulting energy consumptions. Our results confirm that the periurban city is the most energy consuming compare to the axialized and the polycentric cities, but it appears that the global structure of an agglomeration is a second-order factor compared to the inner arrangement of its neighbourhoods.

Does the High-Speed Rail Improve Employment in Peripheral Cities? Evidence From China’s Beijing–Shanghai HSR Line

This study addresses the impacts of high-speed rail (HSR) on the employment rate on the periphery of HSR-connected cities. Using the Chinese municipal-level data sets of 2001 to 2017s, we have found that HSR could improve the average employment in peripheral cities on the route. However, HSR negatively affects employment in small and medium-sized peripheral cities while the large-sized peripheral cities benefit from its operation. Our evidence shows that the “siphon effect” on employment of large-sized peripheral cities on smaller neighbors happened specifically in the manufacturing sectors. This study provides important policy implications for HSR cities with different sizes and characteristics. Small- and medium-sized periphery HSR cities could appropriately response to HSR operation by readjusting the structure of manufacturing sectors, in order to avoiding employment loss.

Big data industry development and carbon dioxide emissions: A quasi-natural experiment

Big data industry development and carbon dioxide emissions reduction are the crucial driver and objective functions of economic growth, respectively. Whether the two types of corresponding policies can achieve the “win-win” effect is the key to green development transformation in the future. However, little attention has been paid to the influence of big data industry development on carbon dioxide emissions. Based on the quasi-natural experiment in China's national big data comprehensive experimental area, the paper identifies the causal effect between big data industry development and carbon dioxide emissions. Specifically, the panel data of 282 cities in China spanning from 2010 to 2019 are used in regression analysis. The study reveals that the big data industry development has a substantial impact in reducing carbon dioxide emissions. Meanwhile, the findings are confirmed by a set of rigorous robustness checks. The heterogeneity analyses suggest that the effect of inhibiting carbon dioxide emissions due to the big data industry development is more significant in eastern & central China, and large-sized cities. In addition, the big data industry reduces carbon dioxide emissions through the effects of industrial structure optimization, technological innovation, and resource allocation. Our findings contribute to the nexus between big data industry development and carbon dioxide emissions. In light of these findings, the paper recommends that governments integrate economic growth and environmental protection policies by promoting big data industry development.

Mapping environmentally sustainable urban development within six US cities through object-based image change analysis of aerial orthoimagery

The rapid expansion of cities and continuous urban population growth underscores a need for sustainable urban development. Sustainable development is that which addresses human needs, contributes to well-being, is economically viable, and utilizes natural resources at a degree sustainable by the surrounding environmental systems. Urban green spaces, green roofs, and solar panels are examples of environmentally sustainable urban development (ESUD), or development that focuses on environmental impact, but also presents the potential to achieve social and economic sustainability. The aim of this study was to map and compare amounts of ESUD c. 2010 and c. 2019 through an object-based image analysis (OBIA) approach using National Agricultural Imagery Program (NAIP) aerial orthoimagery for six mid- to large-size cities in the USA.The results of this study indicate a hybrid OBIA and manual interpretation approach applied to NAIP orthoimagery may allow for reliable mapping and areal estimation of urban green space and green roof changes in urban areas. The reliability of OBIA-only mapping and estimation of areal extents of existing green roofs, and new and existing solar panels, is inconclusive due to low mapping accuracy and coarse spatial resolution of aerial orthoimagery relative to some ESUD features. The three urban study areas in humid continental climate zones (Dfa) were estimated to have greater areal extent of new and existing urban green space and existing green roofs, but less areal extent of new green roofs and existing solar panels compared to the three study areas in humid subtropical climate zones (Cfa).

Financial reform and haze pollution: A quasi-natural experiment of the financial reform pilot zones in China

Financial reform becomes a new tool for environmental governance because it can indirectly affect the environment by promoting economic and financial agglomeration and technological innovation. Despite China's aggressive financial reform pilot (FRP) policy since 2012, little is known about whether and how such policy affects haze pollution (HP). We exploit geographic and temporal variations in China's FRP policy and compile a dataset covering 284 cities over the period from 2003 to 2019. Employing a difference-in-differences (DID) approach, we document that China's FRP policy has a negative causal effect on HP in the pilot cities. The estimates obtained from an instrumental variable constructed by religious temples also support the haze-abatement effect of such policy. This effect is largely driven by advances in technological innovation and increases in economic agglomeration, while financial agglomeration is proven to have little effect. Finally, our estimate is particularly pronounced in cities with high levels of economic development, financial development and technological innovation, and that in large-sized and non-mineral resourced cities. Overall, our findings shed light on the importance of financial reform in environmental governance in a developing country.

Urban Green Innovation Efficiency in China: Spatiotemporal Evolution and Influencing Factors

Investigating urban green innovation efficiency (UGIE) is imperative because it is correlated with the development of an ecological civilization and an innovative country. Spatiotemporal evolution and influencing factors of UGIE are two important scientific problems that are worth exploring. This study presents an indicator system for UGIE that includes input, expected output, and unexpected output, and employs a super-efficiency slacks-based measure (super-SBM) to calculate UGIE in 284 cities at or above the prefecture level in China from 2005 to 2020. Then, we adopted spatial auto-correlation to identify its spatial differences among these cities and Geodetector to evaluate its influencing factors. The results are as follows: (1) The overall UGIE tended to rise, except in northeastern China, megacities, and super large-sized cities. (2) The UGIE of Chinese cities exhibited remarkable spatial differences and auto-correlation, and the “low-low” type enjoyed the most local spatial auto-correlations. (3) Sociocultural factors represented by the number of collections in public libraries became the most important factors affecting the UGIE in China.

Autonomous drone charging station planning through solar energy harnessing for zero-emission operations

• Solar energy from building envelopes can extend UAVs coverage and reliability in last-mile delivery applications. • This integration can omit GHG emissions in parcel delivery while improving building energy efficiency. • A multi-objective optimization model is proposed that maximizes UAV coverage and minimizes the total cost of energy and decarbonization. • A flexible energy use model is applied to a digital twin to generate minimum-energy 3D trajectories. • RI-SHOT multi-objective optimization algorithm is used to solve all the delivery demands. • GHG emissions for the entire UAV charging network are omitted compared to a grid-connected operation. The introduction of Unmanned Arial Vehicles (UAVs) in smart city operations is considered a sustainable technological solution due to the promised significant greenhouse gas emission reductions. This study developed an integrated multi-objective charging infrastructure coverage optimization model that integrates UAV-based operations with solar energy harnessing from building envelopes. This model maximizes UAVs’ coverage range and minimizes the total cost of energy and decarbonization. The model is based on a flexible energy use model for UAVs calibrated to experimental measurements to generate a minimum-energy trajectory. We also developed an origin-destination (O-D) demand geo-referenced in a digital-twin model to replicate real-world operation. Overall, 12,532 simulated daily missions in a large-sized city are modelled. The results show that the proposed system can eliminate GHG emissions. Furthermore, the system can significantly reduce the decarbonization price through associated savings and excess generated electricity. The proposed approach demonstrates avenues to advance smart cities and capitalize on renewable energy.

An investigation of the economic impact of small-scale sports events: The case of a medium-sized city in the Western United States

The current study was designed to bridge a sporting event typological and geographical gap by investigating evidence of the economic impact of five small-scale sports events in the Western region of the United States. Utilizing the input-output economic impact equation established by the Sports Event and Tourism Association, data was collected from participants and spectators through on-site intercept surveys. Data was analyzed using the traditional calculations for economic impact as well as offering real-time economic impact data using an sporting event intercept survey procedure. Results showed small-scale events impact the economy of their host city positively, mainly by filling hotel rooms that would otherwise have gone vacant. Results also show that real-time economic impact data may prove more reliable to future decisions of cities hosting events. Previous research on mid-sized cities hosting sporting events as well as the current research related to small-scale sporting events proves more beneficial than large-scale sporting events in large-sized cities. Given the information from the current study, local sports commissions and political figures may effectively advocate hosting small-scale events to their public using the justification of economic impact (traditional or real-time). Additionally, stakeholders of such events should consider maintaining or expanding the current inventory of small-scale events throughout the calendar year.

The new WHO air quality guidelines for PM2.5: predicament for small/medium cities.

The global burden of disease estimated that approximately 7.1 million deaths worldwide were related to air pollution in 2016. However, only a limited number of small- and middle-sized cities have air quality monitoring networks. To date, air quality in terms of particulate matter is still mainly focused on mass concentration, with limited compositional monitoring even in mega cities, despite evidence indicating differential toxicity of particulate matter. As this evidence is far from conclusive, we conducted PM2.5 bioaccessibility studies of potentially harmful elements in a medium-sized city, Londrina, Brazil. The data was interpreted in terms of source apportionment, the health risk evaluation and the bioaccessibility of inorganic contents in an artificial lysosomal fluid. The daily average concentration of PM2.5 was below the WHO guideline, however, the chemical health assessment indicated a considerable health risk. The in vitro evaluation showed different potential mobility when compared to previous studies in large-sized cities, those with 1 million inhabitants or more (Curitiba and Manaus). The new WHO guideline for PM2.5 mass concentration puts additional pressure on cities where air pollution monitoring is limited and/or neglected, because decision making is mainly revenue-driven and not socioeconomic-driven. Given the further emerging evidence that PM chemical composition is as, or even more, important than mass concentration levels, the research reported in the paper could pave the way for the necessary inter- and intra-city collaborations that are needed to address this global health challenge.

골목상권의 영역 설정과 유형 분류에 관한 연구: 청주시를 사례로

Alley business districts are important market areas to secure retail and commercial marketing competitiveness and stability, most of which has been vulnerable to external shocks, including the COVID-19 pandemic. While, most research studies in South Korea have focused on cases within large cities and high-street business districts such as Seoul and several large-sized cities in Kyuunggi province, few studies have attempted to delineate alley business district on a set of street boundaries in small and medium-sized cities where one-person business owners and self-employed subcontractors, in particular, have been suffered. This study has two main objectives: delineating spatial extents and classifying district types of the alley business districts suitable for small and medium-sized cities in Korea. This study delineates spatial extents using GIS-based data handling and processing techniques with the data sets of individual store coordinates and ‘Gil’ type of the road names available through small enterprise, commercial, and road name address databases. Using the delineating spatial extent and classification results, this study produced alley business districts map of Cheongju city and examined the spatial characteristics of the four types of districts in the city. Finally, we expect that the findings of this study — alley(‘Gil’)-based catchment areas and classification of the alley businesses — may be used as core data and contribute adequately to predicting street-scaled markets and businesses. Besides, the results of this study can serve as a realistic starting point for policymaking to revitalize alley business districts with the understanding and prediction of its district changes.