Large Cities In China Research Articles

Spatiotemporal evolution of COVID-19 infection and detection within night light networks: comparative analysis of USA and China

The spatial distribution of population affects disease transmission, especially when shelter in place orders restrict mobility for a large fraction of the population. The spatial network structure of settlements therefore imposes a fundamental constraint on the spatial distribution of the population through which a communicable disease can spread. In this analysis we use the spatial network structure of lighted development as a proxy for the distribution of ambient population to compare the spatiotemporal evolution of COVID-19 confirmed cases in the USA and China. The Visible Infrared Imaging Radiometer Suite (VIIRS) Day/Night Band sensor on the NASA/NOAA Suomi satellite has been imaging night light at ~ 700 m resolution globally since 2012. Comparisons with sub-kilometer resolution census observations in different countries across different levels of development indicate that night light luminance scales with population density over ~ 3 orders of magnitude. However, VIIRS’ constant ~ 700 m resolution can provide a more detailed representation of population distribution in peri-urban and rural areas where aggregated census blocks lack comparable spatial detail. By varying the low luminance threshold of VIIRS-derived night light, we depict spatial networks of lighted development of varying degrees of connectivity within which populations are distributed. The resulting size distributions of spatial network components (connected clusters of nodes) vary with degree of connectivity, but maintain consistent scaling over a wide range (5 × to 10 × in area & number) of network sizes. At continental scales, spatial network rank-size distributions obtained from VIIRS night light brightness are well-described by power laws with exponents near −2 (slopes near −1) for a wide range of low luminance thresholds. The largest components (104 to 105 km2) represent spatially contiguous agglomerations of urban, suburban and periurban development, while the smallest components represent isolated rural settlements. Projecting county and city-level numbers of confirmed cases of COVID-19 for the USA and China (respectively) onto the corresponding spatial networks of lighted development allows the spatiotemporal evolution of the epidemic (infection and detection) to be quantified as propagation within networks of varying connectivity. Results for China show rapid nucleation and diffusion in January 2020 followed by rapid decreases in new cases in February. While most of the largest cities in China showed new confirmed cases approaching zero before the end of February, most of these cities also showed distinct second waves of cases in March or April. Whereas new cases in Wuhan did not approach zero until mid-March, as of December 2020 it has not yet experienced a second wave of cases. In contrast, the results for the USA show a wide range of trajectories, with an abrupt transition from slow increases in confirmed cases in a small number of network components in January and February, to rapid geographic dispersion to a larger number of components shortly before mobility reductions occurred in March. Results indicate that while most of the upper tail of the network had been exposed by the end of March, the lower tail of the component size distribution has only shown steep increases since mid-June.

Land subsidence in Beijing from 2017-2018 revealed by Sentinel-1A TOPS time series interferometry

Beijing is one of the largest cities in China, which has suffered from land subsidence for a long time. According to the study from 2005 to 2017, the maximum subsidence rate of Beijing is more than 10 cm/year. This paper will use Sentinel-1A TOPS data for the first time to reveal the land subsidence of Beijing from 2017 to 2018 by using time series interferometry. SBAS-InSAR technology was used for time series analysis. The annual mean subsidence rate and time series subsidence of Beijing were obtained. The results show that the east of Chaoyang district and the northwest of Tongzhou district were the severe subsidence areas in Beijing, and the subsidence rate is more than 10 cm/year, which indicates that the subsidence area in Beijing is continuous in recent years, and corresponding measures should be taken by the government.

Implication of excessive length of stay of asthma patient with heterogenous status attributed to air pollution.

Air pollution has potential risk on asthma patients, further prolongs the length of stay. However, it is unclear that the impact of air pollution on excessive length of stay (ELoS) of heterogeneous asthma patients. In this study, we proposed a K-Nearest Neighbor (KNN) embedded approach incorporating with patient status to analyze the impact of short-term air pollution on the ELoS of asthma patients. The KNN embedded approach includes two stages. Firstly, the KNN algorithm was employed to search for the most similar patient community and approximate kernel proxy of each index patient by Euclidean distance. Then, we built the differential fixed-effect linear model to estimate the risk of air pollution to the ELoS. We analyzed 6563 asthma patients' medical insurance records in a large city of China from January to December in 2014. It was found that when the duration of exposure to air pollution (i.e., PM2.5, PM10, SO2, NO2, and CO) reaches around 4-5days, the risk of increasing the ELoS becomes the largest. But only O3 shows the opposite effect. What's more, CO is the dominant risk to increase the ELoS. With a 1mg/m3 increment of CO average concentration in 5days, the ELoS will go up by 0.8157day (95%CI:0.72,0.9114). Based on the kernel proxy in the top 1% similar patient community, the additional financial burden posed on each patient increases by RMB 488.6002 (95%CI:430.1962,547.0043) due to the ELoS. The KNN embedded approach is an innovative method that takes into account the heterogeneous patient status, and effectively estimates the impact of air pollution on the ELoS. It is concluded that air pollution poses adverse effects and additional financial burdens on asthma patients. Heterogeneous patients should adopt different strategies in health management to reduce the risk of increasing the ELoS due to air pollution, and improve the efficiency of medical resource utilization. The online version contains supplementary material available at 10.1007/s40201-020-00584-8.

An Efficient Genetic Method for Multi-Objective Location Optimization of Multiple City Air Terminals

Some airports construct several buildings in city centre to offer check in and other services, denoted as city air terminals, which help passengers to check in and drop off luggage closer to their residences. Multi-objective location optimization methods play an important role in planning the locations of city air terminals. The objectives are to improve passenger experience and enhance the competitiveness of air transportation. A mathematical model of this problem is introduced. The model takes three factors into accounted as the optimization objectives, including the average path length from passengers to city air terminals, the maximum tolerable distance of passengers, and the service capacity of a station. Secondly, an efficient hybrid evolutionary method is presented for efficiently optimizing the locations of city air terminals, which includes an improved ripple-spreading algorithm for solving the many-to-many path optimization problem and a genetic algorithm for optimizing the facility location problem. Finally, a case study based on a large city in China is performed to test the proposed method for locating city air terminals in urban area and to show its effectiveness and efficiency.

Study on the Differences of Urban Forestry Demands of Citizens in Beijing, Shanghai and Guangzhou, China

From a global perspective, urban forestry plays an important role in improving the living environment of urban citizens, expanding the space for urban development, improving human health and well-being, and promoting sustainable economic and social development. In China, Beijing, Shanghai, Guangzhou and other cities have made remarkable achievements in urban forestry development in recent years, which changes people’s demands for urban forestry accordingly, especially for citizens living in the large cities. The degree and dimension of the demands for cities are constantly increasing. In order to study the public demands for urban forestry in the large cities of China, this paper selects Beijing, Shanghai and Guangzhou as the research area, using the method of single factor analysis of variance from gender, age, education, marital status, health status to discuss the three urban citizens in urban forestry total demand, education demand, health demand and recreation demand. The results show that :(1) There is no gender difference in the demand for urban forestry between Shanghai and Guangzhou. Only there is a difference in the educational and cultural demand for urban forestry between males and females in Beijing. And the educational and cultural demand of females is slightly higher than that of males. (2) Unmarried people in the three cities generally have higher educational and cultural demand for urban forestry than married people. (3) In different cities, people of different age groups have different demands for urban forestry. Beijing citizens lay more stress on the educational and cultural demand of urban forestry, Shanghai citizens lay more stress on the recreational demand of urban forestry and Guangzhou citizens lay more stress on the health demand of urban forestry.

Study on commuter travel of urban workers——Analysis of coordination between ground bus and rail transit in Beijing

At present, with the advancement of China’s urbanization construction process, China’s urbanization rate has gradually increased in recent years, and the population in the suburbs and surrounding towns and rural areas continue to pour into large cities, which inevitably leads to a series of social problems in the process of China’s urban economic development. In the process of population gathering in large cities, traffic problems have a great impact on urban workers. With the increase of urban population and the rising stock of private cars, the efficiency of ground transportation continues to decline; the population aggregation in big cities, the poor travel experience of public transport system in the morning and evening rush hours on weekdays, and the long commuting time and distance of workers restrict the long-term development of large cities in China to a certain extent. This paper studies the coordination between ground public transport and rail transit in Beijing with reference to the coordination of the development of ground public transport and rail transit. Finally, based on these problems, this paper puts forward some suggestions for the long-term coordinated development of public transport in Beijing.

Simulating two-phase taxi service process by random walk theory.

City taxi service systems have been empirically studied by a number of data-driven methods. However, their underlying mechanisms are hard to understand because the present mathematical models neglect to explain a (whole) taxi service process that includes a pair of on-load phase and off-load phase. In this paper, by analyzing a large amount of taxi servicing data from a large city in China, we observe that the taxi service process shows different temporal and spatial features according to the on-load phase and off-load phase. Moreover, our correlation analysis results demonstrate the lack of dependence between the on-load phase and the off-load phase. Hence, we introduce two independent random walk models based on the Langevin equation to describe the underlying mechanism and to understand the temporal and spatial features of the taxi service process. Our study attempts to formulate the mathematical framework for simulating the taxi service process and better understanding of its underlying mechanism.

Abundance and characteristics of microplastics in municipal wastewater treatment plant effluent: a case study of Guangzhou, China.

Wastewater treatment plants (WWTPs) have been proposed as significant sources of microplastics (MPs) in freshwater and estuarine environments. WWTPs, even those with high removal efficiencies, release millions of MPs per plant daily. China is the largest plastic producer worldwide, but only a few studies of MP pollution from WWTPs have been carried out in China. In this work, we present a comprehensive report concerning the MPs in effluent from six WWTPs in Guangzhou, which is the third largest city in China. The six WWTPs employ different treatment processes and serve different populations and types of factories. The average abundance of MPs in the effluents of all six WWTPs was 1.719 ± 1.035 MP/L. Fiber was the most common type of MP in the effluent, accounting for 39.48 ± 6.37% of all MPs. Fourier transform infrared spectroscopy confirmed that 35.7% of the particles were plastics, including polyethylene terephthalate (31.9%), polypropylene (26.6%), and polyethylene (9.7%). The results showed that advanced or tertiary treatment technologies could substantially remove MPs and that the size of the population served was positively associated with the abundance of MPs. The number of textile factories was a key factor contributing to the total release of MPs. In addition, the MP shapes and polymer compositions showed that the occurrence of MP types is regional, varies regionally, and is related to the types of factories in the vicinity. More studies on the effects of specific industries are suggested in order to improve the management of wastewater discharge and reduce MPs presence in the natural environment.

Air Quality Changes in Shanghai, China, and the Surrounding Urban Agglomeration During the COVID-19 Lockdown

COVID-2019 (COronaVIrus Disease 2019), discovered at the end of December 2019, has spread around the world, becoming a pandemic. To prevent its spread, many governments implemented strict lockdown measures, including the closure of factories and limitations on travel. These measures led to a decrease in human activity, affecting air pollutant emissions. This study evaluates air quality during the partial lockdown of Shanghai, the largest city in China, and the broader Yangtze River Delta region. It was found that daily concentrations of PM2.5, PM10, SO2, NO2, and CO during the lockdown period were reduced by 9%, 77%, 31.3%, 60.4%, and 3% respectively, compared to the same period in 2019. Even with decreasing concentrations of PM2.5 and PM10, the overall values are still more than four times higher for the lockdown period than the World Health Organization (WHO) recommends for safe concentrations (10 μg/m3 and 20 μg/m3). This indicates the existence of other background sources that continue to make a significant contribution to air pollution in the region even with severe reductions in human activity. This study may be used to guide environmental policy, as it demonstrates to what extent the control of pollution sources can improve air quality.

Ukrainian

The article is devoted to the problems of the development of modern Chinese cities, which describes the development of large Chinese cities in the 20th and 21st centuries, analyzes contemporary problems and the conditions for their formation in the near future. The pur- pose of the article is to show the dynamic development of the largest and most important modern cities in China and the problems that arise in connection with their development. Novelty — first in the periodical literature describes the development of megacities as a ra- tional option for the territorial organization of urban areas. The methodological basis of the article consists of historical-logical and complex approach, tabular and graphical me- thods of presenting research results. In the 80s, the fi rst special economic zones were created. His process was characterized by the introduction of elements of the free market, the de- collectization of agriculture, changes in the sectoral structure of the economy and its ration- alization. A prolonged concentration of the population in large cities of China causes their further expansion and the formation of large metropolitan clusters — megacities. Given the development of the Chinese economy, it should be understood that its participation in international exchange, despite notable progress, still too small; expansion in world markets occurs with low quality and, as a result, with low prices for Chinese goods; China’s growing position in the global economy is predominantly quantitative rather than qualitative. To con- solidate China as one of the leaders in the process of economic globalization, it is important to ensure the eff ective management of such large centers of concentration of human and material resources as megacities. In this regard, much attention is paid to the analysis of trends and the conditions for the further development of Chinese cities. It is determined that in 20-25 years, more than 1,000,000,000 Chinese citizens will live in large cities. Th e process of converting them into a new modifi ed form, megalopolises, will continue. Th e factors that will infl uence the development of modern megacities, and the set of internal processes for their further development (political, social, economic, ethnic, religious and environmental) that require some structuring are identifi ed. Th e negative aspects of urbanization were iden- tifi ed: growing income inequality and a deterioration in population structure. To overcome these phenomena, restructuring of the regional economy and measures to overcome inequa- lity are considered useful, where preference is given to income distribution mechanisms de- pending on the quality of labor, stimulation of social responsibility of employers and others. Th is assessment of China’s demographic policy is aimed at improving family planning.

City size and energy conservation: Do large cities in China consume more energy?

Although the nexus between urbanization and energy consumption has been widely discussed at the macro level or in specific areas such as in relation to residents and transport, how the expansion of city size affects energy consumption in the process of urbanization is still unknown. Clarifying this impact mechanism is necessary for China to achieve its energy conservation goals. In this context, based on a systematic theoretical elaboration, this study constructs an econometric model of the nexus between city size and energy use and performs a series of robust empirical analyses through the endogenous control of instrumental variables. The results show that the current expansion of China's city size tends to positively affect energy consumption; however, as city size continues to expand, energy consumption will exceed the critical value and change from increasing to decreasing. In this process, it is easier to achieve a decline in energy intensity than a decline in per capita energy consumption. Cities with a population exceeding 1 million in their urban districts are more conducive to reducing energy use. Compared with the expansion of urban built-up areas, an increasing population agglomeration can more effectively promote the decline of urban energy consumption. This study provides policy makers with new ideas about urban planning and energy conservation.

The association between an increased reimbursement cap for chronic disease coverage and healthcare utilization in China: an interrupted time series study.

Hypertension and diabetes are highly prevalent in China and pose significant health and economic burdens, but large gaps in care remain for people with such conditions. In this article, drawing on administrative insurance claim data from China's Urban Employee Basic Medical Insurance (UEBMI), we use an interrupted time series design to examine whether an increase in the monthly reimbursement cap for outpatient visits using chronic disease coverage affects healthcare utilization. The cap was increased by 50 yuan per chronic disease on 1 January 2016, in one of the largest cities in China. Compared with the year before the increase, patients with only hypertension increased their spending using chronic disease coverage by 17.8 yuan (P < 0.001) or 11.6%, and those with only diabetes increased their spending using chronic disease coverage by 19.5 yuan (P < 0.001) or 10.6%, with the differences almost entirely driven by spending on drugs. In addition, these two groups of patients reduced their spending using standard outpatient coverage by 13.9 yuan (P < 0.001) or 5.7% and 14.9 yuan (P = 0.03) or 5.2%, respectively, and thus had no changes in total outpatient spending. Patients with both hypertension and diabetes, meanwhile, increased their spending using chronic disease coverage by 54.8 yuan (P < 0.001) or 18.1% and decreased their spending using standard outpatient coverage by 16.1 yuan (P = 0.002) or 6.1%, with no changes in their probability of hospitalization. Among patients with both hypertension and diabetes who had fewer-than-average outpatient visits in 2015, the hospitalization rate decreased after the 2016 reimbursement cap increase (adjusted odds ratio = 0.702, P = 0.01). These findings suggest that increasing financial protection for patients with hypertension and diabetes may be an important strategy for reducing adverse health events, such as hospitalization, in China.

The effect of travel restrictions on the geographical spread of COVID-19 between large cities in China: a modelling study

BackgroundTo contain the spread of COVID-19, a cordon sanitaire was put in place in Wuhan prior to the Lunar New Year, on 23 January 2020. We assess the efficacy of the cordon sanitaire to delay the introduction and onset of local transmission of COVID-19 in other major cities in mainland China.MethodsWe estimated the number of infected travellers from Wuhan to other major cities in mainland China from November 2019 to February 2020 using previously estimated COVID-19 prevalence in Wuhan and publicly available mobility data. We focused on Beijing, Chongqing, Hangzhou, and Shenzhen as four representative major cities to identify the potential independent contribution of the cordon sanitaire and holiday travel. To do this, we simulated outbreaks generated by infected arrivals in these destination cities using stochastic branching processes. We also modelled the effect of the cordon sanitaire in combination with reduced transmissibility scenarios to simulate the effect of local non-pharmaceutical interventions.ResultsWe find that in the four cities, given the potentially high prevalence of COVID-19 in Wuhan between December 2019 and early January 2020, local transmission may have been seeded as early as 1–8 January 2020. By the time the cordon sanitaire was imposed, infections were likely in the thousands. The cordon sanitaire alone did not substantially affect the epidemic progression in these cities, although it may have had some effect in smaller cities. Reduced transmissibility resulted in a notable decrease in the incidence of infection in the four studied cities.ConclusionsOur results indicate that sustained transmission was likely occurring several weeks prior to the implementation of the cordon sanitaire in four major cities of mainland China and that the observed decrease in incidence was likely attributable to other non-pharmaceutical, transmission-reducing interventions.

Mobile instant messaging or face-to-face? Group interactions in cooperative simulations

The capability of learners to work cooperatively and to coordinate efforts in a team is becoming more important to the success of any job and advancement of knowledge. In cooperative learning, the literature regarding the impact of social technologies is controversial. Because of this controversy, the object of this study is to examine students’ experiences and feedback regarding teamwork in cooperative simulation interactions. The research object was addressed in a two-phase study with an experimental design. The participants were 328 students of 6 classes from a large city in China. In this experiment, communication through face-to-face encounters, mobile instant messaging, and combinations thereof were executed based on qualitative and quantitative data. Our research results describe the differences between experimental treatments. Various relevant teaching implications are discussed as well.

Using Open Big Data to Build and Analyze Urban Bus Network Models within and across Administrations

Urban bus networks play an important role, when the capacity of urban public services is evaluated. With recent advancements in Internet and Communication Technologies, there is an emerging interest in building an urban bus network model through open big data. This has rarely been investigated and exposes several challenges in the provision of transportation services in urban planning. On the one hand, it is necessary to combine bus stations based on spatial distance constraints due to their ambiguous definition in open big data; on the other hand, it is difficult and time-consuming to relocate and build new stations, but the optimization of bus lines is relatively easy to implement. This study aimed to develop an explicit methodological framework for building and analyzing two different types of urban bus network model using open big data. Thereafter, the framework was applied in two case studies in China, within a county-level administration and in a region including three county-level administrations. The key result shows that there was a shortage of urban bus services across these different administrations. This paper contributes to the body of research methodologies into public transport networks and to understanding the sharing of urban public services across administrations, improving the management of urban bus networks, and highlighting the importance of examining the characteristics of urban bus network in county-level administrations rather than just in large cities in China.

Distribution of High-sensitivity C-reactive Protein Status in an Urban Population in China

ObjectivesTo evaluate the distribution by age and sex of serum high-sensitivity C-reactive protein (hsCRP) in an urban Chinese population and to provide a profile prediction for the risk of bacterial infection, inflammatory diseases, or tissue damages in the body. MethodsSerum hsCRP was determined using the Roche Tina-quant immuno-turbidimetric assay on a Hitachi 7600–010 automatic biochemical analyzer (Roche Diagnostics) in 1,572 males and 1,800 females, including 78 pregnant women, who were derived from the National Health and Nutrition Survey in 2010–2012. ResultsThe average hsCRP concentration in urban China was 0.68 mg/L for males and 0.65 mg/L for females. Significant differences in hsCRP were found among different age groups (P < 0.05). Monitoring results showed no significant differences among the 6–11, 45–59, and ≥ 60-year-old groups in the comparison of hsCRP between males and females in large cities. However, hsCRP concentration was significantly higher in men aged 12–17 and 18–44 years than in women. ConclusionThe distribution of the hsCRP status of residents in large cities in China was influenced by age and gender, and the hsCRP levels of both sexes increased gradually with age. In addition, hsCRP concentration was higher in healthy pregnant women than in non-pregnant women. Basing on our results, we recommend that this parameter be included in future national and international screening for early detection of various illnesses.

Spatiotemporal changes of heat waves and extreme temperatures in the main cities of China from 1955 to 2014

Abstract. In the past decades, severe heat waves have frequently occurred in many parts of the world. These conspicuous heat waves exerted terrible influences on human health, society, the economy, agriculture, the ecosystem and so on. Based on observed daily temperatures in China, an integrated index of heat waves and extreme-temperature days was established involving the frequency, duration, intensity and scale of these events across large cities in China. Heat waves and extreme-temperature days showed an increasing trend in most regions except northwest China from 1955 to 2014. After the late 1980s, the increasing trend was more obvious than the decades before. The cities in the middle and lower reaches of the Yangtze River were threatened by the most serious heat events in the past 60 years, especially Chongqing and Changsha. Due to the subtropical monsoon climate and special terrain, Chongqing experienced the most heat events in a long period of time. In particular, there was obvious fluctuation of hot years in 31 cities, which did not continuously rise with global warming; 21 cities mainly located in the eastern and southern regions of China had an obvious rising trend; eight cities had a clear declining trend which was mainly distributed in the western and northern regions of China; and there were no extreme-temperature days in Kunming and Lhasa in the past 60 years. The study revealed an obvious differentiation of heat events for 31 cities under climate change; heat threat in most cities is increasing but declining or remaining unchanged in the other cities. The trend is likely to intensify with global warming.

A Study on the Risk Management in the Multi-housing Development Process Stages in Local Large Cities of China

A Study on the Risk Management in the Multi-housing Development Process Stages in Local Large Cities of China

Comparison of health care utilization among users of public and private community health centres in urban China

In China, the government has encouraged the participation of private sector facilities in primary care to improve health care quality. We compare health care utilization patterns among patients who select private versus public community health centres (CHCs) for reimbursed outpatient services. This paper uses data from the Urban Employee Basic Medical Insurance scheme from 2013 to 2016 in one of the largest cities in China. We used a Poisson model and a logistic model to examine outcomes on monthly outpatient visits and the probability of hospitalization, respectively. Compared with being a user of a public CHC, being a user of a private CHC is associated with a 26.2% lower incidence rate of outpatient visits to hospitals [95% confidence interval (CI): 30.1-21.8%] and no difference in rates of visits to CHCs or hospitalization. Among patients with diabetes or hypertension, being a user of a private CHC is associated with a 12.9% lower incidence rate of outpatient visits to CHCs (95% CI: 19.8-5.4%), a 25.6% lower incidence rate of outpatient visits to hospitals (95% CI: 21.4-19.5%) and 22.3% higher odds of hospitalization (95% CI: 3.5-44.7%). Being a user of a private CHC is associated with a reduction in outpatient visits to hospitals, which aligns with the goal of reducing hospital congestion at the outpatient level. For patients with chronic diseases, being a user of a private CHC is associated with a higher probability of hospitalization. More research is needed to understand the reason for this difference.

Urban Atmospheric Environment Quality Assessment by Naturally Growing Bryophytes in Central China.

Bryophytes are popular biomonitoring plants for atmospheric environments. The objectives of this study were to examine the characteristics of bryophyte communities, determine a suitable monitor species, and assess urban atmospheric environment quality by the joint use of bryophyte features and chemical properties in a large city in China. A pleurocarpous feather moss Haplocladium angustifolium was recognized as a good biomonitor of atmospheric deposition in central China by investigating bryophyte communities and habitat environment in various ecological function regions of the urban areas in Wuhan. The concentrations of trace elements, including As, Cd, Co, Cr, Cu, Mn, Ni, V, Pb, and Zn, in moss and soil samples from 25 sampling sites were analyzed by inductively coupled plasma mass spectrometry. The concentrations of Cd and Zn in Haplocladium angustifolium collected from the entire study area were much higher than those in substrate soil. Cd was at the highest ecological risk level among the 10 elements, which contributed 34.5% to the potential ecological risk index (RI). An RI value of 392.8 indicated that urban atmospheric quality in Wuhan was in a considerable potential ecological risk. The index of atmospheric purity, regarding species richness, cover, and frequency of bryophytes, was spatially and negatively correlated with RI, also demonstrated the atmospheric quality. Effective measures should be considered to alleviate certain airborne trace element contamination and protect the environment and human health in this metropolis.