城市空间结构对交通出行影响研究的进展——单中心与多中心的论争

通过多中心城市空间结构的构建来疏解单中心城市的交通拥挤是城市规划历来的理想,但这种理想正日益受到实证研究的挑战.关于多中心空间结构能否节省通勤距离与通勤时间,存在截然相反的观点.分析表明,两种截然相反的实证结论源于两种不同形成机制的多中心结构,改善交通出行的多中心结构是以就业与居住就地平衡为前提的.     

论北京城市副中心建设

北京"单中心、同心圆式"的城市空间格局,使城市功能过度集中于中心城区,给中心城区造成了严重的交通拥堵和环境压力,限制了北京综合承栽能力的提升,影响到北京的可持续发展.东京、巴黎等都通过建设"副中心"解决了城市发展中的空间矛盾.北京应借鉴国际大都市发展经验,启动建设京西副中心、通州-亦庄副中心和顺义副中心,打造分散疏解中心区功能的重要空间栽体,解决北京城市发展中的空间结构矛盾.     

区域空间结构对城市碳排放强度的影响

基于2003～2019年的城市面板数据,运用多种计量模型实证分析区域空间结构对城市碳排放强度的影响和作用机制。结果表明：单中心空间结构与城市碳排放强度呈现先抑制后促进的U型关系。产业集聚的技术溢出效应是单中心空间结构影响城市碳排放强度的重要机制。单中心空间结构对城市碳排放强度的影响会因地区和城市特征不同表现出异质性,东部地区、中心城市和经济发展水平较高城市碳排放强度的U型关系更明显。鉴于此,应加快中心城市建设,强化中心城市集聚溢出效应;各省应因地制宜地制定差异化发展策略;积极引导人口有序流动,推进产业合理布局。     

探索识别中心的新方法——以上海生产性服务业空间分布为例

结合地统计方法(Geo-Statistics)和城市空间结构模型,提出了一种较为客观和科学的识别城市中心的新方法,即首先运用全局和局部Moran指数判别潜在的城市中心,然后运用回归分析进行检验和甄别.利用上海工商局企业数据进行分析,结果表明:上海生产性服务企业高度集聚于中心城区,并形成两个中心:外难中央商务区和南京西路,国内企业倾向集聚于外滩而海外企业倾向于南京西路.这种双中心格局和国外城市中呈现出的"绝对分散"或者"多中心"格局并不相同,反映了我国城市空间结构演变的自身特点.     

首都圈区域空间就业分布结构分析

基于第二次全国经济普查分区县18个行业的就业人口数据,以局部空间自相关G系数为衡量标准,对首都圈120个地理单元的就业热点即集聚中心进行判定,分析首都圈的区域空间结构。运用SOFM神经网络聚类对区域内分区县的行业门类进行聚类,探讨首都圈内部各城市职能分工以及首都圈经济结构及空间组合特征。研究表明:首都圈呈现"‘一主一次’双核、一廊、七中心"的区域空间结构特征;北京和天津在区域内具有综合性服务职能,河北七地市的中心城区职能各有侧重,但都具有地区性中心的职能。     

论北京城市“副中心”建设

北京“单中心、同心圆式”的城市空间格局,使城市功能过度集中于中心城区,给中心城区造成了严重的交通拥堵和环境压力,限制了北京综合承载能力的提升,影响到北京的可持续发展。东京、巴黎等都通过建设“副中心”解决了城市发展中的空间矛盾。建议北京借鉴国际大都市发展经验,启动建设京西副中心、通州——亦庄副中心和顺义副中心,打造分散疏解中心区功能的重要空间载体,解决北京城市发展中的空间结构矛盾。     

基于大数据的城市就业空间特征与影响因素研究——以南京市中心城区为例

大数据的出现为城市就业空间的精细化研究和规划带来新的契机,以手机信令数据为基础,融合多源数据手段,通过多尺度GIS空间分析、单中心与多中心模型验证、规划对比分析与二元逻辑回归等四个方面深入分析城市就业空间特征与影响因素,并以南京市中心城区作为实证分析对象,主要结果如下:①随着空间尺度的不断缩小,就业空间结构的多中心性初步显现,城市外围的大厂新村与徐庄高新区基本形成副中心,但新街口主中心依然强势,与其周边地区呈现出紧密粘连的一体化特征.②城市规划与现实发展仍存在一定差距,高新技术产业创新带缺乏就业人口集聚,中心体系规划中的主中心发展较为滞后,需因地制宜持续强化多中心空间结构.③在就业空间主中心—副中心—密集区—稀疏区不同层级之间,影响因素的作用机制与空间模式存在明显差异,应着重在多类型交通协同、公共服务设施均等化与产城融合发展方面制定相应的优化策略.     

近20年中国特大城市空间结构演变

研究了全国52个特大城市1990~2008年城市空间结构的演变特征。研究表明:中国特大城市空间结构出现了多中心、多轴线的演变,多中心结构、带状结构和放射结构城市数量增多;城市空间结构多中心演变特征在1990~2000年表现更加明显,多轴线的演变特征在2000~2008年表现更加明显;城市空间结构的演变主要受城市空间规模扩大,城市产业结构类型和城市空间增长方式等因素的影响。最后基于1990~2008年中国特大城市空间结构演变的研究将中国城市空间结构演变归纳为单中心结构分化、轴线结构强化、单中心结构回归三种基本模式。     

北京市中心体系职能类别及空间结构分析

北京作为中国的首都,发展和建设商务中心区,是首都经济功能扩展的必然需要,对于推动北京经济社会发展,改善北京城市形象,确立北京在经济全球化中的地位,都有重要的意义。本文对北京市城市中心体系从职能类别和空间结构两方面进行了概述。     

文化产业集聚对国际创意大都市空间结构重构的影响

20世纪中期以来,世界城市经历了从工业城市到现代创意城市的演变与发展.城市演变与发展的关键在于城市产业经济的结构变迁导致了城市空间结构的巨大变化:文化产业在国际创意大都市中心城区的集聚改变了中心城区的功能、改变了过去单中心的城市形态而构建了多中心的城市形态,并带来了国际创意大都市人口、土地及就业密度的变化.     

The Structure of Sprawl: Identifying and Characterizing Employment Centers in Polycentric Metropolitan Areas

This paper applies a consistent framework to four comparably sized metropolitan areas to identify and characterize their employment centers. Employment centers are identified as places that exceed a threshold employment density and a threshold employment level. They are also characterized as specializing on the basis of location quotient analysis. We find clear evidence of specialization in every employment center in the four metropolitan areas studied. Our interpretation is that what we are observing is a systematic change in metropolitan structure rather than a random sprawling of firms. We also find some evidence that the size distribution of employment centers follows the rank-size rule. This suggests that there is structure not only in the distribution of economic activity among the employment centers but also in their size distribution. Because less than 50 percent of metropolitan employment is within employment centers, future research should focus on understanding the more diffuse employment patterns. The rank-size rule gives some guidance as to the expected size distribution of employment throughout the metropolitan area.     

Intra-urban location of manufacturing employment in Colombia

This paper describes the spatial distribution of manufacturing employment in Bogota and analyzes the changes in the location patterns over the 1970–1975 period using industrial directory data. The analysis shows strong evidence of the spatial decentralization of manufacturing employment owing to a steady movement of firms outward from central areas; new large firms with more than 100 employees tend to locate near the periphery while the births of small firms tend to take place near the center. Measures of concentration indicate an increasing dispersion of manufacturing establishments during the period.     

Population and employment densities: structure and change

"We examine spatial patterns and their changes during the 1970s for the Los Angeles region, by estimating monocentric and polycentric density functions for employment and population. Downtown Los Angeles is clearly identified as the statistical monocentric center of the region, and it is the most consistently strong center in the polycentric patterns. Polycentric models fit statistically better than monocentric models, and there was some shift in employment distribution toward a more polycentric pattern. These findings verify the existence of polycentricity in Los Angeles and demonstrate for the first time that employment and especially population follow a polycentric pattern based on exogenously defined employment centers. The results confirm that both employment and population became more dispersed during the 1970s."     

A synthesis of the production function and the shift-share model : A new regional modelling approach

The purpose of this paper is to suggest a new approach to regional modelling and show the way by which regional expansion paths of output and employment can be developed. Basically, the theoretical model is a synthesis of the production function for the industry (or region), the shift-share model, and a set of hypotheses and a number of identifies concerning the growth components of employment. The growth components of employment specified by the shift-share model and explained by the hypotheses enter and modify the production function in the sense that the shift-share model is linked directly to the production function in which the labor factor appears disaggregated into three distinct components (regional-share, industrial-mix, and national growth component). The theoretical model was tested for the manufacturing industry of the Greek economy. The policy implications of this model center around the fact that policy-makers can affect regional economic variables towards the desired level and direction.     

On the Endogeneous Formation of Secondary Employment Centers in a City

A new approach is proposed to explain the formation of secondary employment centers in a monocentric city. Specifically, a large firm considers locating a new plant in a city where none of the existing businesses has a significative share of the labor force, so that its location can be viewed as a secondary employment center. The choice of this location results from the interplay between the process of competition on both the labor and land markets and the technological externalities generated by the proximity of the city center where other firms are located.     

Urban agglomeration effects and employment and wage gradients

When employment occurs at both central and non-central points, but firms have a preference to be near the center, the rent gradient will decline, and a wage gradient is necessary to compensate workers for more centrally located employment. Wage gradients and rent gradients are jointly determined. The relationship between wage offer functions and the equilibrium wage gradient is derived, the latter dependent on utility functions and commuting costs. This is illustrated with a two sector model incorporating agglomeration economies in the export sector. Numerical solution reveals how agglomeration economies affect wages, employment, and city size.     

Factor substitution,employment density and suburbanization

A model of an urban area producing one good for export is presented and solved to yield the employment density function. The production technology is a constant elasticity of substitution (σ) production function, unlike other models which use a Cobb-Douglas function. The shape of the employment density function proves to be sensitive to the elasticity of substitution and can diverge markedly from the usually assumed negative exponential form. The employment density function is a constant when σ = 0; always declines for positive σ but at an increasing rate if $\text{σ ≤}\text{1}\text{2}$; at either an increasing rate near the city center and decreasing thereafter or always at a decreasing rate if $\text{1}\text{2}\text{< σ < 1}$; and at a decreasing rate if σ ≥ 1. When the employment density function is differentiated with respect to σ, the sign of the derivative is positive near the city center and generally negative in the outer regions; the city seems to centralize. A decline in transport costs does not always suburbanize employment; it is contingent on the nature of the production technology.     

开拓创新 加快计量事业发展的探索

面对计量检定机构在发展中遇到的难题,本中心与时俱进、开拓创新,找到了一条适合自身发展的道路。本文通过介绍"双向选择,竞聘上岗;增加设备投入,扩大检定范围;加强人才培养与引进,注重职工文化建设;加强横向联合,实现资源共享"阐述了计量检定机构可持续发展道路。     

THE INNOVATION‐EMPLOYMENT NEXUS: A CRITICAL SURVEY OF THEORY AND EMPIRICS

Understanding whether technical change is beneficial or detrimental for employment is at the center of the policy debate, especially in phases of economic recession. So far, the effects of innovation – in its manifold declinations and intrinsic complexity – on labor demand have proven to be not unequivocal. This essay critically reviews the role of technical change in shaping employment dynamics at different levels of aggregation. First, it disentangles theoretically the role of different compensation mechanisms through which employment adjusts after an innovation is introduced. Second, it critically presents the most recent empirical evidence on the topic, with a focus on methods and limitations. Finally, it provides an attempt to conceptualize a number of stylized facts and empirical regularities on the innovation‐employment nexus.     

天河学院赛特莱特机电专业实践教育中心建设

高等学校应用型本科人才培养的成效,直接关系到学生的就业与社会的发展。而实践教育作为理论学习后,验证所学理论中最重要的一环。校企合作搭建实践教育中心,为学生实习提供帮助。