Nonlinear relationship between urban form and transport CO_(2)emissions:Evidence from Chinese cities based on machine learning

Reducing carbon emissions from the transport sector is essential for realizing the carbon neutrality goal in China.Despite substantial studies on the influence of urban form on transport cO_(2)emissions,most of them have treated the effects as a linear process,and few have studied their nonlinear relationships.This research focused on 274 Chinese cities in 2019 and applied the gradient-boosting decision tree(GBDT)model to investigate the nonlinear effects of four aspects of urban form,including compactness,complexity,scale,and fragmentation,on urban transport CO_(2)emissions.It was found that urban form contributed 20.48%to per capita transport CO_(2)emissions(PTCEs),which is less than the contribution of socioeconomic development but more than that of transport infrastructure.The contribution of urban form to total transport CO_(2)emissions(TCEs)was the lowest,at 14.3%.In particular,the effect of compactness on TCEs was negative within a threshold,while its effect on PTCEs showed an inverted U-shaped relationship.The effect of complexity on PTCEs was positive,and its effect on TCEs was nonlinear.The effect of scale on TCEs and PTCEs was positive within a threshold and negative beyond that threshold.The effect of fragmentation on TCEs was also nonlinear,while its effect on PTCEs was positively linear.These results show the complex effects of the urban form on transport CO_(2)emissions.Thus,strategies for optimizing urban form and reducing urban transport carbon emissions are recommended for the future.

Spatiotemporal Differentiation of Urban Spatial Form and Carbon Emissions in Poyang Lake City Group

In response to the inherent requirements of low-carbon land spatial planning in Jiangxi Province and the lack of existing research,this paper explored the mechanism of spatial form elements of Poyang Lake urban agglomeration on urban carbon emissions.Based on generalized linear regression and geographically weighted regression models,this paper analyzed the spatiotemporal distribution characteristics of carbon emissions,the spatiotemporal relationship between urban form index and carbon emissions,and the spatial differentiation of the intensity of dominant factors from 63 county-level administrative units in the Poyang Lake city group from 2005 to 2020.The results showed that:①The carbon emissions of urban agglomerations around Poyang Lake are generally increasing,and the spatial distribution of carbon emissions is characterized by high-value concentration in the middle and low-value agglomeration in pieces;②The main driving factor for the spatial heterogeneity of carbon emissions was the expansion of built-up area;③Improving urban compactness and optimizing urban form could effectively reduce urban carbon emissions.The results showcased the correlation between urban spatial landscape pattern and the spatiotemporal distribution of carbon emissions,which could make the low-carbon land spatial planning in the Poyang Lake city group more reasonable and practical.

Urban Spatial Form Optimization Strategies Based on the Principle of Climate Adaptability of Regional Architecture: A Case Study of Traditional Cave Dwelling Villages in Northern Shaanxi Province

A multitude of climate-adaptive design approaches are embedded in regional architecture,which have a positive impact on addressing the deformed development of urban spatial patterns and the dual challenges of climate and resources.This paper examines the principles of climate adaptability embedded in the site layout and spatial organization characteristics of traditional cave dwelling villages in northern Shaanxi Province.The extracted climate adaptability principles are summarized,and the resulting design strategies that are well-suited to the contemporary urban space form are presented.Through analysis,it can be observed that traditional cave dwelling villages in northern Shaanxi are predominantly situated on south-facing slopes in proximity to water at low altitudes.These villages are characterized by compact building groups and east-west development,which is constrained by the elements of mountains and rivers.A two-level street system is generated,comprising streets parallel to the contour line and roadways perpendicular to the contour line.This results in the formation of a courtyard form enclosed by mountains.Such site layout and spatial organization exhibit excellent climate adaptability with regard to heat,ventilation,and wind storage.In light of the aforementioned considerations,the following urban spatial form design strategies are put forth:①the topographic height difference can be exploited to obtain sufficient sunshine;②the group shape can be optimized in order to reduce building energy consumption;③the best orientation of the building can be chosen to take account of both winter and summer conditions;④the height and length can be combined in order to form natural masking;⑤the D/H ratio of streets and roadways should be controlled to achieve a balance between heat gain and cooling of groups;⑥vents should be set appropriately to optimize group ventilation;⑦climate buffers should be established to increase the level of climate response.

Evolution of the“Golden Royal City”:Analytical study on urban forms of ancient capital cities in Myanmar

The historical cities in Southeast Asia with distinct characteristics are an important part of Asia’s cultural heritage system and the ancient capitals of Myanmar are as an example of these civilizational achievements.Their urban forms through history are essential spatial carriers reflecting the traditional local planning thinking.However,the overall understanding has yet to form due to a lack of systematic research.This study aims to complement it by studying the urban forms of almost all Myanmar’s ancient capitals based on verifiable spatial elements,works of literature,archaeology documents and field survey.The location,boundary and layout elements are analyzed to classify and characterize these urban forms,and their evolution rules are then summarized.Furthermore,the urban planning characteristics are discussed,indicating that the regulated structure and distinctive image gradually formed,accompanied by increasingly mature planning thinking and methods.The study reveals that the urban form and the planning thinking of Myanmar’s ancient capital cities had undergone an evolution with its own characteristics and that the“Golden Royal City”is of unique value in the genealogy of Asian capitals.The findings will contribute to the mutual learning between civilizations and provide a scientific foundation for the heritage conservation.

Urban Dynamics and Emergence of New Centers in the Dakar Region (Senegal)

Due to the status of the Dakar region as the former capital of AOF (French West Africa) and current capital of the Republic of Senegal, it is home to a very large part of the population and most of the socio-economic, administrative and cultural activities on a very small area of the country (0.28%). This situation makes it a very attractive region and subject to strong land pressure. The objective of this article is to study past and current urban dynamics as well as changes in natural spaces, in order to identify new urban centers. The methodological approach consists in analyzing satellite images to understand the evolution of different forms of spatial occupation in the Dakar region, and to study population movement flows and urban forms in order to reveal new urban centers. The results of the study show that the Dakar urban space is characterized by diverse forms which express a heterogeneous set of spaces. They also revealed the emergence of new clusters between 1986 and 2016, notably Ngor, Grand Yoff, Parcelles Assainies in the North-West, and Keur Massar and the North of the communes of Rufisque in the eastern part of the Dakar region.

Realizing the Box-counting Method for Calculating Fractal Dimension of Urban Form Based on Remote Sensing Image

In the research of fractal cities, the fractal dimension is very important. It is used to describe the fractal character of the city. The authors have designed two approaches to calculate the fractal dimension by the box-counting method through an example of Beijing, which are called the vector method and the grid method, respectively. The former calculates the fractal dimension through an intersecting analysis in ArcView; and the latter is carried out by programming in Matlab. They are compared from three aspects： the calculating process, the limits in use, and the results. As a result, the conclusion is made that there are merits and faults on both methods, and they should be chosen to use properly in practical situation.

Spatial investigation of the temporal urban form to assess impact on transit services and public transportation access

The rapid urban growth in developing city increases the requirement of the efficient and sustainable public transportation system.The urban growth affects the urban form,which indicates the change in human and urban development activity.Urban form affects directly and indirectly access to the public transportation system as an assessment of potential riders and proximity to stops increase transit services users.Therefore,access is one of the important aspects for the assessment of transit service efficiency.Public transportation access can be represented by a coverage area and useful to estimate potential riders of public transportation.In this study,a Geographical Information System(GIS)-based spatial statistical analysis method is used to examine the spatial relationship of different urban form indicators with population or riders of transit service in a coverage area and to ascertain how urban form influences public transportation trips in this coverage area.The coverage area is delineated using a GIS-based road/street network distance approach.The spatial analysis results suggested that urban forms have certain impact on trips in coverage area at both ward level and zone level.The statistical analysis implies that significant and positive values of spatial lag coefficient indicate a positive spatial interaction between wards and variable like total coverage area;worker density have shown positive and significant effects on trips of public transportation.

Construction of a refined population analysis unit based on urban forms and population aggregation patterns

The population analysis unit(PAU)is the basic unit employed in studies of urban populations.The commonly used PAUs are mostly administrative divisions,regular geographic grids.However,these units are different from urban forms,and cannot be used to consider the characteristics of population distributions and flow changes.In this study,we proposed a method for constructing a fine population analysis zone(FPAZ)based on the population aggregation pattern and urban form elements.First,considering the spatial structure of a city and the fine-grained demands of population analysis,the basic analysis unit was divided according to the functional heterogeneity of the population activity region at the micro-scale by combining urban form elements.Next,a population aggregation preference model was established by considering the spatial distribution characteristics of the local aggregation of the urban population flow and long-term stability characteristics depending on the dynamic changes in entrances and exits.Finally,we divided the FPAZ combined with the microstructural elements.Experimental results showed that compared with other types of PAUs,the FPAZ was more consistent with the urban morphology and was an appropriate and general spatial unit for expressing the accurate characteristics of population distributions and changes at the micro-scale.

A novel unsupervised deep learning method for the generalization of urban form

Accurate delineation of urban form is essential to understand the impacts that urbanization has on the environment and regional climate.Conventional supervised classification of urban form requires a rigidly defined scheme and high-quality sample data with class labels.Due to the complexity of urban systems,it is challenging to consistently define urban form types and collect metadata to describe them.Therefore,in this study,we propose a novel unsupervised deep learning method for urban form delineation while avoiding the limitations of conventional super-vised urban form classification methods.The novelty of the proposed method is the Multiscale Residual Convolutional Autoencoder(MRCAE),which can learn the latent representation of differ-ent urban form types.These vectors can be further used to generalize urban form types by using Self-Organizing Map(SOM)and the Gaussian Mixture Model(GMM).The proposed method is applied in the metropolitan area of Guangzhou-Foshan,China.The MRCAE model along with SOM and GMM is used to generalize the urban form types from satellite images.The physical and functional properties of each urban form type are also analyzed using several auxiliary datasets,including building footprints,Points-of-Interests(POIs)and Tencent User Density(TUD)data.The results reveal that the urban form map generated based on the MRCAE can explain 55%of the building height distribution and 55%of the building area distribution,which are 2.1%and 3.3%higher than those derived from the conventional convolutional autoencoder.As the information of urban form is essential to urban climate models,the results presented in this study can become a basis to refine the quantification of urban climate parameters,thereby introducing the urban heterogeneity to help understand the climate response of future urbanization.

Impact of Urban Form on Household Carbon Emission: Case Studies on Some Neighborhoods

Based on 1,400 pieces of questionnaires collected in Beijing, this study applies LISA to identify the spatial clustering households with high and low carbon emissions, and explores the relationship between household carbon emissions and urban forms via intensive case studies on five neighborhoods. Results indicate that all of building density, land use pattern, employment accessibility, and public transportation accessibility influence remarkably on household carbon emissions, which suggests that the rational planning of urban form is necessary for the construction of low-carbon cities.

A New Interpretation in Urban Form of the Wards of Tang Chang'an

By comparing the gridiron plans of ancient western cities with that of Tang Chang'an in the same scale,the authors find that a residential ward of Tang Chang'an was about the same size as an ancient western city.Thus the paper puts forward a hypothesis that Tang Chang'an was not a single city,but a cluster of hundreds of small towns with rigid layout.This theory is then proved by comparing a ward of Tang Chang'an with a typical small town in China from the perspectives of town scale,spatial layout,residential density,and land-use.The authors further explain the main cause for this unique urban form of Tang Chang'an,which was the compulsory migration policy.

京杭大运河沿线主要城市空间形态的综合测度研究

京杭大运河作为连接中国南北地区之间的经济、文化发展与交流的走廊,历来对促进沿河城市兴起与繁荣发挥着关键作用。研究选取京杭大运河沿线8个主要城市的空间形态进行对比研究,利用空间句法对城市空间网络进行解构,并分析各个城市内部结构的不同之处;运用城市分形维数和紧凑度指数对不同城市进行计算,对城市空间外部形态特征进行分析;并将这些城市分为城市空间形态简单、城市空间形态较复杂和城市空间形态复杂三大类。最后根据分析结果提出针对性的城市发展建议,以期为大运河沿线城市以及此类其他沿河城市的空间形态发展提供参考。

先秦时期城市形态研究

中国传统城市模式具有深刻的哲学底色和文化内涵,但随着对营城建制的不断关注,主要的研究成果却集中在秦汉及之后的王朝时期,先秦时期城市发展尚未得到重视。该文将先秦城市作为研究目标,致力于探究先秦城市形态发展的整体趋势。先秦城市形态分为对称式和非对称式两种,并分别辨析不同形态出现的具体原因,继而指出两种形态间的关联系时代变化下城市职能转变所致。最后通过对现有城市遗址归纳整理,得出先秦城市形态以对称式为主,非对称式为辅的结论。

南京河西鱼嘴核心区城市设计中的一体化形态建构与管控

在新城核心区设计中,如何基于自然与人工资源特征进行形态整合往往是实现集约化开发的重要抓手。而在实施管控的过程中,通常会经历专题论证、实践反馈和动态调整的过程。以南京河西鱼嘴核心区为例,回顾其规划历程,总结其在滨江城市环境形态建构与管控中的关键策略,为当代中国高密度核心区的城市建筑一体化开发提供参考。

形态演变和驱动发展:天津城市空间拓展与影响因素研究

我国的城市发展已由增量扩张转为存量优化,通过对处于稳定发展阶段城市的空间形态和拓展因素的研究,有助于挖掘城市发展的规律特征,对未来的城市规划和城市更新起到引导和调控作用,促进城市转向高质量可持续发展。文章以天津市为例,以1985—2020年的城市遥感影像数据为基础,利用GIS工具对天津的城市扩张进行定量化和可视化分析,并通过逻辑回归(logistic regression)的方法,利用社会经济数据对影响城市发展的因素进行定量化研究,以探寻城市扩张的规律和驱动因素,为城市的更新发展探寻方向。

国外韧性城市形态研究述评

面对突发的自然和人为灾害,城市表现出极大的脆弱性。韧性城市形态被认为是化解城市脆弱性的关键得到关注,梳理国外研究成果对应对我国快速城市化进程中的不确定灾害风险具有重要意义。以韧性城市形态为主题,从概念与特征、形态要素韧性表现、评估及韧性设计等方面追踪国外研究进展。研究结果表明:国外文献重点探讨了形态与自然灾害的关联;韧性城市形态的概念尚未达成一致意见;从宏观、中观、微观空间层次视角探讨城市形态要素韧性表现成果较多;形态要素韧性评估集中于道路网络要素的韧性表现;形态要素韧性设计关键在于空间异质性。基于分析结果可知,我国未来研究重点应集中在全方位构建韧性城市形态研究框架、丰富并拓展形态要素韧性评估方法与技术、重视形态要素空间异质性等方面。

我国城市形态对空气质量影响的研究进展

近年来城市形态对空气质量的影响研究引起了国内学者的广泛关注,获得了大量研究成果,但仍然缺乏系统梳理。作者以中国期刊全文数据库(CNKI)和美国科学情报研究所Web of Science核心合集为数据源,采用文献归纳法和CiteSpace软件,对2000至2022年发表的我国城市形态对空气质量影响的文献进行了系统分析。研究发现:年度发文量整体呈上升趋势,2017年后英文文献发文量高于中文文献量,中英文研究机构重合度较低,缺少合作研究;研究主要以区域尺度和局地尺度为主,微观尺度街谷和西部的研究偏少;研究方法以统计分析、遥感和GIS的融合应用为主,数值模拟方法应用较少;城市规划与环境保护、空气污染与影响是研究热点,城市形态测度指标、城市形态对空气质量影响因素、相关性分析是主要的研究内容;土地审批、交通排放、人口分布、城市设计、植被覆盖是缓解空气污染的重要途径。

上海市城市形态与边界真空对城市活力的影响分析

长期以来,城市活力一直是城市规划理论讨论的重点.为了研究上海市的城市形态和边界真空因素对城市活力的影响,使用GWR和GD模型分析了相关因素对城市活力的影响机制.结果表明,边界真空和城市形态与城市活力密切相关,边界真空一定程度上不满足雅各布斯的相关理论;城市活力与城市形态密切相关,良好的道路小街区特性可以有效增强行人出行能力,主干路(边界真空)不可距离居民日常出行点过近.此外,城市的交通设施(如地铁站)可以很好地增强居民远距离出行的能力,对居民的步行具有刺激作用.最后,本文呼吁城市在规划初期,应该考虑边界真空和城市形态对居民出行行为的吸引性和便捷性,以便于日常居民生活.

上海地区高温过程中局地气候区尺度城市热岛特征分析

本文以超大城市上海为研究对象,选取2017年7月为夏季代表月,利用自动气象站网观测得到的逐小时气温和风速数据,基于局地气候分区方法分析了上海市各局地气候区(Local Climate Zone,LCZ)在不同天气条件下的气温和城市热岛强度(Urban Heat Island Intensity,UHII)时空特征及其成因。结果表明:由于城市几何形态、建筑材料、表面不透水面占比以及人类活动的不同,上海市夏季典型月各LCZ的气温和UHII表现出明显差异,在高温日,UHII日变化曲线可以分为"W"型、浅"U"型、"V"型、日间型和平稳型这五类。城市建筑形态对城市风、热环境具有较为复杂的影响,UHII与天空可视因子(Sky View Factor,SVF)的相关系数在00时(北京时,下同)为负,而在12、16时为正,这是由于建筑物对城市冠层内的辐射传输的影响和建筑物的热量储存导致的;城乡风速之比与SVF在00、12和16时都为正相关,说明了高大密集的建筑物对风速有衰减作用,同时风速通过影响大气的平流输送进一步影响UHII。

高密度城市人口动静集聚与街坊形态关联解析——基于曼哈顿的实证

高密度城市中人口具有高度流动性,其动静态人口的集聚现象和城市空间形态之间存在着一定程度的关联性。本文以曼哈顿为例,回溯其城市建设与形态演进轨迹,基于当前市域范围内静态和动态人口数据,运用空间聚类分析和曼哈顿人口探索器,识别出人口密度的空间分布特征。然后分别选取两个动、静态人口密度集中的1 km×1 km城市地段切片,通过空间矩阵分析其中典型街坊形态的量值特征,结果发现4个地段的形体密度存在梯度分异格局,并且与人口动静态分布的差异化现象相关。在此基础上,辨识并抽象出高密度街坊的组构类型,并揭示构成影响城市形态的隐性秩序和关联因素,最后提出曼哈顿城市形态对我国高密度城市建设的三点启示。