Urban Three-dimensional Expansion and Its Driving Forces——A Case Study of Shanghai,China

Urban expansion is a phenomenon of urban space increase,and an important measuring index of the process of urbanization.Taking Shanghai as an example,the changes of urban average height and built-up area were studied to represent city's vertical and horizontal increases respectively,and statistical methods were used to analyze the driving forces of urban expansion.The research drew following conclusions:1) The urban expansion process of Shanghai from 1985 to 2006 had a clear periodic feature,and could be divided into three stages:vertical expansion in dominance,coordinated vertical and horizontal expansion,and horizontal expansion in dominance.2) The average height and quantity of buildings in core city were significantly bigger than those in suburbs,but the changing speed of the latter was faster.And 3) urbanization process was the major driving force for the city's horizontal expansion,while industrial structure improvement was the key driving factor for the vertical expansion.Those two driving forces were simultaneously affected by city's political factors.

Evaluation of Three-dimensional Urban Expansion: A Case Study of Yangzhou City, Jiangsu Province, China

With rapid urban development in China in the last two decades, the three-dimensional(3D) characteristic has been the main feature of urban morphology. However, the vast majority of researches of urban growth have focused on the planar area(two-dimensional(2D)) expansion. Few studies have been conducted from a 3D perspective. In this paper, the 3D urban expansion of the Yangzhou City, Jiangsu Province, China from 2003 to 2012 was evaluated based on Geographical Information System(GIS) tools and high-resolution remote sensing images. Four indices, namely weighted average height of buildings, volume of buildings, 3D expansion intensity and 3D fractal dimension are used to quantify the 3D urban expansion. The weighted average height of buildings and the volume of buildings are used to illustrate the temporal change of the 3D urban morphology, while the other two indices are used to calculate the expansion intensity and the fractal dimension of the 3D urban morphology. The results show that the spatial distribution of the high-rise buildings in Yangzhou has significantly spread and the utilization of the 3D space of Yangzhou has become more efficient and intensive. The methods proposed in this paper laid a foundation for a wide range of study of 3D urban morphology changes.

Two-and Three-Dimensional Urban Core Determinants of the Urban Heat Island： A Statistical Approach

There is no doubt that the UHI （urban heat island） is a mounting problem in built-up environments, due to the energy retention by surface dense building materials, leading to increased temperatures, air pollution, and energy consumption. Much of the earlier research on the UHI has used two-dimensional （2-D） information, such as land uses and the distribution of vegetation. In the case of homogeneous land uses, it is possible to predict surface temperatures with reasonable accuracy with 2-D information. However, three-dimensional （3-D） information is necessary to analyze more complex sites, including dense building clusters. In this research, 3-D building geometry information is combined with 2-D urban surface information to examine the relationship between urban characteristics and temperature. The research includes the following stages： （1） estimating urban temperature; （2） developing a 3-D city model; （3） generating geometric parameters; and （4） conducting statistical analyses using both linear and non-linear regression models. The implications of the results are discussed, providing guidelines for policies aiming to reduce the UHI.

Impact of Urban 3D Morphology on Particulate Matter 2.5(PM2.5) Concentrations:Case Study of Beijing, China

Urban particulate matter 2.5(PM2.5)pollution and public health are closely related,and concerns regarding PM2.5 are widespread.Of the underlying factors,the urban morphology is the most manageable.Therefore,investigations of the impact of urban three-dimensional(3D)morphology on PM2.5 concentration have important scientific significance.In this paper,39 PM2.5 monitoring sites of Beijing in China were selected with PM2.5 automatic monitoring data that were collected in 2013.This data set was used to analyze the impacts of the meteorological condition and public transportation on PM2.5 concentrations.Based on the elimination of the meteorological conditions and public transportation factors,the relationships between urban 3D morphology and PM2.5 concentrations are highlighted.Ten urban 3D morphology indices were established to explore the spatial-temporal correlations between the indices and PM2.5 concentrations and analyze the impact of urban 3D morphology on the PM2.5 concentrations.Results demonstrated that road length density(RLD),road area density(RAD),construction area density(CAD),construction height density(CHD),construction volume density(CVD),construction otherness(CO),and vegetation area density(VAD)have positive impacts on the PM2.5 concentrations,whereas water area density(WAD),water fragmentation(WF),and vegetation fragmentation(VF)(except for the 500 m buffer)have negative impacts on the PM2.5 concentrations.Moreover,the correlations between the morphology indices and PM2.5 concentrations varied with the buffer scale.The findings could lay a foundation for the high-precision spatial-temporal modelling of PM2.5 concentrations and the scientific planning of urban 3D spaces by authorities responsible for controlling PM2.5 concentrations.

Three-Dimensional Urban Thermal Effect across a Large City Cluster during an Extreme Heat Wave:Observational Analysis

Given extensive and rapid urbanization globally,assessing regional urban thermal effects(UTE)in both canopy and boundary layers under extreme weather/climate conditions is of significant interest.Rapid population and economic growth in the Yangtze River Delta(YRD)have made it one of the largest city clusters in China.Here,we explore the three-dimensional(3D)UTE in the YRD using multi-source observations from high-resolution automatic weather stations,radiosondes,and eddy covariance sensors during the record-setting heat wave(HW)of July-August 2013.It is found that the regional canopy layer UTE is up to 0.6-1.2℃,and the nocturnal UTE(0.7-1.6℃)is larger than daytime UTE(0.2-0.5℃)during the HW.The regional canopy layer UTE is enhanced and expanded northwards,with some rural sites contaminated by the urban influences,especially at night.In the boundary layer,the strengthened regional UTE extends vertically to at least 925 hPa(~750 m)during this HW.The strengthened 3D UTE in the YRD is associated with an enlarged Bowen ratio difference between urban and non-urban areas.These findings about the 3D UTE are beneficial for better understanding of the thermal environment of large city clusters under HW and for more appropriate adaption and mitigation strategies.

唐山广场舞空间考察

广场舞是唐山市民休闲活动中的重要部分,本文通过对唐山主城区广场舞空间的观察记录,将其空间分为十字路口的广场舞空间、步行道旁的广场舞空间、城市公园的广场舞空间3种类型,并从空间特点、活动形式、组织方式等角度对其进行分析。

基于城市交通路口车辆拥堵疏散路径设计方法研究

文章对于城市交通路口车辆拥堵问题,完成了疏散路径方法的设计。以各帧线段间交点的出现频率为依据,完成对车道线和车辆消失点位置的确定,针对事故多发区域,为对变换后车辆位置进行确定,组建路段车道坐标变换方程,对车辆进行跟踪匹配时,给出其状态特征,在路口交通流状态的隶属函数的获取上,采用模糊推理实现,对于路段交通流速度和流量,给出其变化特征,据此完成疏散路径的设计,经实验检测后表明该设计方法具有较高的精确度。

城市立体交叉方案的集对分析模型研究

基于集对分析理论，提出了城市立体交叉设计方案的评价模型．运用层次分析法建立了各评价指标的层次结构，确定其权重，消除了专家评定确定权重时的人为因素干扰，提高了设计方案评价的可信度，为城市立体交叉设计方案的选优提供了简单、实用的评价方法。

城市高架桥街谷空气环境和污染物扩散的数值模拟

采用Fluent 6.3数值模拟,研究含高架桥的十字路口在不同风向条件下,街谷内空气流场和污染物浓度场特征.模拟结果表明:当来流风向平行于高架桥主干道方向时,来流在高架桥上引桥下方收缩形成低风速涡旋,造成高浓度CO淤积,随着高架桥水平路段的延伸,高架桥下方CO浓度逐渐降低,而高架桥上方行人呼吸高度处CO始终保持极高浓度;当来流风向垂直于高架桥主干道方向时,高架桥改变了污染物的爬墙效应,其下方主干道迎风面和背风面CO不易扩散,保持较高浓度;行人应避免长期在高架桥下方、街谷背风面及十字路口拐角处停留,以减轻街谷内污染物对人体造成的伤害;十字路口处引入高架桥会改变污染源的位置、强度,改变来流风的流动特性,从而影响街谷中污染物的扩散.

城市道路十字路口高精度DEM建模方法研究

十字路口作为城市道路系统的重要组成部分,现有的城市道路DEM建模方法在十字路口处存在形态失真的现象。针对这一问题,本文提出边界线收敛法构建高精度十字路口DEM。首先选取主干道,再提取形态缓冲区并赋予其边界高程,最后对道路和缓冲区进行高程点加密和内插构建十字路口DEM。本文以南京市1:500数字线划地图(DLG)道路网数据对十字路口模型构建进行研究。结果表明,本文方法能够适用不同路口的建模,且与其他构建道路模型的方法相比,该方法所构建的十字路口DEM形态符合真实的十字路口形态,能够较好地支撑构建高精度道路DEM。

Underground space planning in Helsinki

This paper gives insight into the use of underground space in Helsinki,Finland.The city has an underground master plan(UMP) for its whole municipal area,not only for certain parts of the city.Further,the decision-making history of the UMP is described step-by-step.Some examples of underground space use in other cities are also given.The focus of this paper is on the sustainability issues related to urban underground space use,including its contribution to an environmentally sustainable and aesthetically acceptable landscape,anticipated structural longevity and maintaining the opportunity for urban development by future generations.Underground planning enhances overall safety and economy efficiency.The need for underground space use in city areas has grown rapidly since the 21 st century;at the same time,the necessity to control construction work has also increased.The UMP of Helsinki reserves designated space for public and private utilities in various underground areas of bedrock over the long term.The plan also provides the framework for managing and controlling the city’s underground construction work and allows suitable locations to be allocated for underground facilities.Tampere,the third most populated city in Finland and the biggest inland city in the Nordic countries,is also a good example of a city that is taking steps to utilise underground resources.Oulu,the capital city of northern Finland,has also started to ‘go underground’.An example of the possibility to combine two cities by an 80-km subsea tunnel is also discussed.A new fixed link would generate huge potential for the capital areas of Finland and Estonia to become a real Helsinki-Tallinn twin city.

基于Petri网的城市交叉口系统仿真分析

针对传统交叉口交通系统分析方法的不足,构建了一个广义随机Petri网的城市十字路口交通系统模型。该模型描述了城市交通的动态性和随机性,并依据仿真过程中的有关信息进行性能分析,以仿真结果论证了公交优先策略的合理性,提出使用Petri网作为模拟设计交叉口信号控制系统,改进高峰时段公交车通行率,解决了动态研究分析系统指标求解繁琐的问题,对城市交通管理、建设规划及发展提供了一定的理论参考。

基于T字路口的城市规划

从目前引起交通堵塞的主要原因入手,分析了用T字路口代替十字路口的可行性,将T字路口应用到城市规划中,提出"蜂窝状"城市规划的设想。

Local climate zone mapping using remote sensing:a synergetic use of daytime multi-view Ziyuan-3 stereo imageries and Luojia-1 nighttime lightdata

The local climate zone(LCZ)scheme has been widely utilized in regional climate modeling,urban planning,and thermal comfort investigations.However,existing LCz classification methods face challenges in characterizing complex urban structures and human activities involving local climatic environments.In this study,we proposed a novel LCZ mapping method that fully uses space-borne multi-view and diurnal observations,i.e.daytime Ziyuan-3 stereo imageries(2.1 m)and Luojia-1 nighttime light(NTL)data(130 m).Firstly,we performed land cover classification using multiple machine learning methods(i.e.random forest(RF)and XGBoost algorithms)and various features(i.e.spectral,textural,multi-view features,3D urban structure parameters(USPs),and NTL).In addition,we developed a set of new cumulative elevation indexes to improve building roughness assessments.The indexes can estimate building roughness directly from fused point clouds generated by both along-and across-track modes.Finally,based on the land cover and building roughness results,we extracted 2D and 3D USPs for different land covers and used multi-classifiers to perform LCZ mapping.The results for Beijing,China,show that our method yielded satisfactory accuracy for LCZ mapping,with an overall accuracy(OA)of 90.46%.The overall accuracy of land cover classification using 3D USPs generated from both along-and across-track modes increased by 4.66%,compared to that of using the single along-track mode.Additionally,the OA value of LCZ mapping using 2D and 3D USPs(88.18%)achieved a better result than using only 2D USPs(83.83%).The use of NTL data increased the classification accuracy of LCZs E(bare rock or paved)and F(bare soil or sand)by 6.54%and 3.94%,respectively.The refined LCZ classification achieved through this study will not only contribute to more accurate regional climate modeling but also provide valuable guidance for urban planning initiatives aimed at enhancing thermal comfort and overall livabillity in urban areas.Ultimately,this study paves the way for more comprehensive and effective strategies in addressing the challenges posed by urban microclimates.