Urban boundaries, an essential property of cities, are widely used in many urban studies. However, extracting urban boundaries from satellite images is still a great challenge, especially at a global ...scale and a fine resolution. In this study, we developed an automatic delineation framework to generate a multi-temporal dataset of global urban boundaries (GUB) using 30 m global artificial impervious area (GAIA) data. First, we delineated an initial urban boundary by filling inner non-urban areas of each city. A kernel density estimation approach and cellular-automata based urban growth modeling were jointly used in this step. Second, we improved the initial urban boundaries around urban fringe areas, using a morphological approach by dilating and eroding the derived urban extent. We implemented this delineation on the Google Earth Engine platform and generated a 30 m resolution global urban boundary dataset in seven representative years (i.e. 1990, 1995, 2000, 2005, 2010, 2015, and 2018). Our extracted urban boundaries show a good agreement with results derived from nighttime light data and human interpretation, and they can well delineate the urban extent of cities when compared with high-resolution Google Earth images. The total area of 65 582 GUBs, each of which exceeds 1 km2, is 809 664 km2 in 2018. The impervious surface areas account for approximately 60% of the total. From 1990 to 2018, the proportion of impervious areas in delineated boundaries increased from 53% to 60%, suggesting a compact urban growth over the past decades. We found that the United States has the highest per capita urban area (i.e. more than 900 m2) among the top 10 most urbanized nations in 2018. This dataset provides a physical boundary of urban areas that can be used to study the impact of urbanization on food security, biodiversity, climate change, and urban health. The GUB dataset can be accessed from http://data.ess.tsinghua.edu.cn.
Green areas cool the climate of a city, reduce the energy consumption caused by the urban heat island (UHI) effect, and bring along carbon savings. However, the calculation of carbon savings due to ...the cooling effect of green areas is still not well understood. We have used a Landsat Enhanced Thematic Mapper Plus (ETM+) image of Beijing, to identify the cooled areas, compute the possible energy used to maintain the temperature differences between cooled areas and their surrounding heated areas, and calculate the carbon savings owing to the avoidance of energy use. Results show that a total amount of 14315.37 tons carbon savings was achieved in the study area and the amount was related to the biomass, the size and the shape of green areas. These results demonstrate the importance of carbon savings resulting from green areas' cooling effect.
► We provide an integral equation for the calculation of energy conservation and carbon savings. ► We show that carbon savings is partly influenced by green areas' features. ► A strong correlation between biomass, size and shape of green areas and carbon savings.
An integral equation for the calculation of energy conservation and carbon savings; Showing that carbon savings is partly influenced by green areas' features.
Urban renewal planning and development are vital for enhancing the living quality of city residents. However, such improvement activities are often expensive, time-consuming, and in need of ...standardization. The convergence of remote sensing technologies, social big data, and artificial intelligence solutions has created unprecedented opportunities for comprehensive digital planning and analysis in urban renewal development and management. However, fast interdisciplinary development imposes some challenges because the data collected and the solutions built are defined piece by piece and require further fusion and integration of knowledge, evaluation standards, systematic analyses, and new methodologies. To address these challenges, we propose a municipal and urban renewal development index (MUDI) system with data modeling and mathematical analysis models. The MUDI system is applied and studied in three circumstances: (1) at regional level, 337 cities are selected in China to demonstrate the MUDI system’s comparable analysis capabilities on a large scale across cities; (2) at city level, 285 residential communities are selected in Xiamen to demonstrate the use of remote sensing data as key MUDIs for a temporal urban land change analysis; and (3) at the level of residential neighborhoods’ urban renewal practices, Xiamen’s Yingping District is selected to demonstrate the MUDI system’s project management capabilities. We find that the MUDI system is highly effective in municipal and urban data model building through the abstraction and summation of grid-based satellite and social big data. Secondly, the MUDI system enables comprehension of the high dimensionality and complexity of multisource datasets for municipal and urban renewal development. Thirdly, the system is applied to enable the use of the newly developed UMAP algorithm, a model based on Riemannian geometry and algebraic topology, and the carrying out of a principal component analysis for the key dimensions and an index correlation analysis. Fourthly, various artificial intelligence-driven algorithms can be developed for urban renewal analyses based on the MUDIs. The MUDI system is a new and effective method for urban renewal planning and management that can be flexibly extended and applied to various cities and urban districts.
China implemented the first phase of its National Healthy Cities pilot program from 2016-20. Along with related urban health governmental initiatives, the program has helped put health on the agenda ...of local governments while raising public awareness. Healthy City actions taken at the municipal scale also prepared cities to deal with the COVID-19 pandemic. However, after intermittent trials spanning the past two decades, the Healthy Cities initiative in China has reached a crucial juncture. It risks becoming inconsequential given its overlap with other health promotion efforts, changing public health priorities in response to the pandemic, and the partial adoption of the Healthy Cities approach advanced by the World Health Organization (WHO). We recommend aligning the Healthy Cities initiative in China with strategic national and global level agendas such as Healthy China 2030 and the Sustainable Development Goals (SDGs) by providing an integrative governance framework to facilitate a coherent intersectoral program to systemically improve population health. Achieving this alignment will require leveraging the full spectrum of best practices in Healthy Cities actions and expanding assessment efforts. FundingTsinghua-Toyota Joint Research Fund "Healthy city systems for smart cities" program.
A series of memorials to the throne written by Chao Cuo (200-154 B.C.), a high-ranking official of the Western Han Dynasty (206 B.C.-A.D. 24), contained systematic thoughts and methods of border city ...planning, and could be regarded as a valuable 2200-year-old document of planning history. Based on the textual interpretation of the classical texts, a historical analysis method that mixes theoretical construction and empirical evidence is applied to analyse the planning thoughts and methods proposed in Chao Cuo's works, including the strategic layout of human and land resources at the territorial scale, city site selection based on natural geographical conditions, multi-scale constructions of physical space from region to residence and social governance balancing people's livelihood and military affairs. The purpose of the planning system proposed by Chao Cuo was to build cites that were suitable for both military defence and people's daily lives, so that people would settle in the frontier and form a stable military force to resist enemies. Chao's works explain a typical feature of ancient Chinese city planning as an instrument of political governance, and demonstrated the interaction between urban form and way of life.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Effective spatial planning of urban communities plays a critical role in the sustainable development of cities. Despite the convenience brought by geographic information systems and computer-aided ...design, determining the layout of land use and roads still heavily relies on human experts. Here we propose an artificial intelligence urban-planning model to generate spatial plans for urban communities. To overcome the difficulty of diverse and irregular urban geography, we construct a graph to describe the topology of cities in arbitrary forms and formulate urban planning as a sequential decision-making problem on the graph. To tackle the challenge of the vast solution space, we develop a reinforcement learning model based on graph neural networks. Experiments on both synthetic and real-world communities demonstrate that our computational model outperforms plans designed by human experts in objective metrics and that it can generate spatial plans responding to different circumstances and needs. We also propose a human-artificial intelligence collaborative workflow of urban planning, in which human designers can substantially benefit from our model to be more productive, generating more efficient spatial plans with much less time. Our method demonstrates the great potential of computational urban planning and paves the way for more explorations in leveraging computational methodologies to solve challenging real-world problems in urban science.
Non-communicable diseases have replaced infectious diseases as the leading cause of death among urban residents; the percentage of years of life lost because of such diseases as a fraction of ...all-cause years of life lost increased from 50·0% (95% CI 48·5–53·0) in 1990 to 77·3% (76·5–78·1) in 2015.4 Health inequality also increased in urban areas.5 China has acted to address urban health challenges by passing strict environmental regulations and investing heavily in urban infrastructure.In traditional chinese medicine, human health is seen as the consequence of harmonisation between human beings and their environments and between the various parts of the human body and the focus is on disease prevention rather than treatment.16 Concepts from traditional Chinese medicine, such as the maintenance of regular daily activities (rest, diet, and exercise) and avoidance of negative health effects from environmental factors (eg, Fengshui) have become essential parts of Chinese culture.In 2007 alone, particulate matter with a diameter of less than 2·5 μm (PM2·5) affected the productivity of about 72 million workers in 30 Chinese provinces, causing an estimated economic loss of ¥346·3 billion (US$44·4 billion, about 1·1% of the national gross domestic product GDP).19 Total economic losses attributed to the public health effects of pollution from particulate matter with a diameter of less than 10 μm (PM10) and sulphur dioxide (SO2) pollution in 74 cities were estimated to be as high as ¥439·8 billion ($70·9 billion, about 2·3% of these cities' GDP) in the first half of 2015.20 China will also have a massive future burden of non-communicable diseases—most of which will affect urban areas—that will strain future health systems and limit economic growth in the country.Total annual premature deaths from such diseases are expected to increase from 3·11 million in 2013 to 3·52 million in 2030.21 Between 2012 and 2030, economic losses attributable to five key non-communicable diseases–ischaemic heart disease, cerebrovascular disease, diabetes, breast cancer, and chronic obstructive pulmonary disease–will total $23·03 trillion USD,22 which is more than twice of China's total GDP in 2015 ($11·07 trillion).
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