An Overall Urban System: Integrating Central Place Theory and Urban Network Idea in the Greater Pearl River Delta of China

Following a half century of popularity, central place theory experienced 20 years of neglect when the new urban system theory of network modeling gained attention at the beginning of the 1990s. However, central place theory remains valid, and it seems there has been a reemergence with it. Using the Greater Pearl River Delta (Greater PRD) as an experimental study region, this paper intends to present an empirical study that validates central place theory and shows that it can be integrated into an overall regional urban system. The study uses the compound Central Place Importance (CPI) to evaluate whether there is a hierarchy among the urban centers within the study area. The results indicate the existence of a hierarchy. Furthermore, empirical observation finds distinct complementarity relationships, rank-size distributions, and co-operative actions between the different cities, thus substantiating the claim that central place theory can be incorporated into an overall regional urban system. Besides, the presence of the densely distributed modern infrastructure system also appears to constitute a dimension of the overall urban system. There need further theoretical and empirical studies in order to support this proposition.

Stability of Spatial Structure of Urban Agglomeration in China Based on Central Place Theory

This paper brings forward the concept of stability of the spatial structure of urban agglomeration(UA)based on Central Place Theory by introducing centrality index and fractal theory.Before assessment,K=4 is selected as parameter to calculate centrality index and fractal dimension(K represents the quantitive relationship between city and the counties in Central Place Theory),and then found the number of nodes,the type of spatial structure,the spatial al-location of nodes with different hierarchy affecting the stability of spatial structure.According to spatial contact direction and the level of stability,UAs in China are classified into five types.Finally,it is posed as a further question that how to use hierarchical relation K=6 and K=7 in central place system to coordinate with the assessment of stability of spatial structure is brought forward.

Spatial Structure of Central Places in Jilin Central Urban Agglomeration, Jilin Province, China

Using the radius of gyration from fractal theory, this paper describes the calculation of fractal dimensions for the four tiers of central places in the Jilin Central Urban Agglomeration(JCUA), Jilin Province, China and the structural characteristics of each tier: 1) the 1st tier central place, Changchun Proper(not including Shuangyang District), provides the most service functions and has the most stable primate position; 2) the 2nd tier central places, Jilin Proper, Siping Proper, Liaoyuan Proper and Songyuan Proper have unclear statuses and do not provide certain functions; 3) the 3rd tier central places comprise 23 county-level cities, counties and urban districts(including Shuangyang District of Changchun), exhibiting a dense spatial structure that agrees with theory; 4) the 4th tier contains the largest number of central places(248 designated towns), but they are loosely distributed. In this study, a spatial image of the JCUA was created, based on vectorized data of the urban settlement distribution, which was then modified and abstracted to create a hexagonal network covering the JCUA. Compared to the traditional central place model, the modified spatial image conforms to the K = 3 principle. In reality, however, the growth of some 3rd tier central places should be increased with the cities being upgraded to the 2nd tier so as to overcome that tier′s functional deficiency. The loose distribution in the 4th tier should also be changed. This apparent anomaly can be explained by the fact that the classic hexagon model used to describe the way market areas layout does not exist in the real world. However, this should not be viewed as an obstacle to using central place theory. If its assumptions are properly applied, it can still assist research into the spatial structure of regions.

SOME EMPIRICAL EXAMPLES OF CENTRAL PLACE MODEL IN CHINA'S RURAL AND URBAN STUDIES

At the beginning of the 1980s, the Central Place Theory(CPT) was introduced into China from the West. The authors of this article are the initiators of applying this model to China's urban and regional planning as well as to the allocation of commercial activities. Since the commodity economy has been developing in China for thousands of years,most of the areas in eastern plains and inland basins of the country show the spatial structure of typical central places scene. During some six years, the authors participatd in a lot of rural, urban and regional planning projects in which the spatial phenomena and relevant internal mechanism proved this medel and its deformation. This paper gives only a few examples of the application of CPT in China. 1. The distribution of rural markets: the empirical study is based mainly on the situation in Shengfang Town and its vicinal area, 2. The spatial combination of urban Systems; problems about city allocation in North China are emphasized, 3. Commercial centres in city and the networks: a crucial study on commercial distribution of the metropolis Beijing is done by using the central place model.

Diverse foraging strategies of breeding Swinhoe's Storm-petrel in the productive marginal sea of the Northwest Pacific

Understanding the foraging behavior is essential for investigating seabird ecology and conservation,as well as monitoring the well-being of the marine environment.Breeding seabirds adopt diverse foraging strategies to maximize energy gains and cope with the intensified challenges of parenting and self-maintenance.Such tradeoff may stem from the heterogeneity of food resources and the constraints of central place foraging.Nevertheless,abundant marine productivity could alleviate the energy limitation for seabirds,resulting in a consistent foraging approach.Here,we investigated the foraging strategy during the breeding season of a cryptic small-sized seabird,Swinhoe’s Storm-petrel(Hydrobates monorhis),in the Yellow Sea,a productive marginal sea of the Northwest Pacific.Using GPS tracking,we evaluated habitat preference,quantified the foraging strategy,and tested if environmental conditions and individual traits influence foraging trips.We found that Swinhoe’s Storm-petrels preferred nearshore areas with shallow water and engaged in primarily short foraging trips.Distinctive southeastward and southwestward strategies emerged when combining trip metrics,including foraging direction,duration,and maximum distance.The bathymetry,proximity to the coastline,and sea surface temperature differed in two foraging strategies.Foraging strategies exhibited flexibility between individuals,potentially explained by wing morphology,in which longer-winged birds are more likely to embark on longer-distance foraging trips.These findings highlight the impact of environmental factors and individual traits on seabirds’foraging decisions in productive marginal sea ecosystems.Our study also provides valuable insights into the foraging ecology of this Asian endemic storm-petrel.

URBAN GROWTH, TRANSPORTATION SYSTEM AND COMMERCIALNETWORK OF BEIJING

In this afticle, three uopt problems on the developlnent and plabong of Beijing metropolis are expounded (1) Having analyzed the process of urbanlzation dunng 45 years, the autihor divides it into three Stages :city expansion, qrban sprawl and fonmation of centnpotal urban nngr. Then a rank-number-size law is pLif fotward to predict the development and allocation of satellite towns (2) Having looked back on the change of urban transpoftation nforork, the atlthor points out its merits and demerits.According to the increases of traffic flow, improving measures for the urban road systems are demonstrated. (3) Having reviewed the llistory of commercial distnbution and referred to previous lnodels, the author roprds the spatial structure of business as a combined network from central place and idealized stnucture of lnetropolitan area. The trade and service orgaluzation in n1ain urban area and peripheral zone can be planned with defferent ways. The atlthor predicts a rational network of commerce and service of Beijing with a strong BCD Which is accepted by some trade authorities

2020-2021年苏州市公共场所集中空调通风系统卫生状况

目的了解苏州市公共场所集中空调通风系统卫生状况。方法采用随机抽样的方式于2020年7—8月至2021年8—9月对苏州市区正常使用的38家次集中空调通风系统进行卫生监测,检测送风中PM_(10)、细菌总数、真菌总数、β-溶血性链球菌,风管内表面细菌总数、真菌总数、积尘量,冷却水中嗜肺军团菌,依据《公共场所集中空调通风系统卫生规范》(WS 394-2012)和《公共场所卫生检验方法》(GB/T 18204.5-2013)进行采样和检测。结果2020—2021年检测的38家次集中空调通风系统中,检测指标总体合格率为93.8%,各场所中宾馆酒店合格率最高,医疗场所合格率较低,差异有统计学意义(χ^(2)=11.87,P<0.05)。集中空调送风指标PM_(10)、细菌总数、真菌总数、β-溶血性链球菌合格率分别为97.8%、92.4%、76.1%、100.0%,各指标间差异有统计学意义(χ^(2)=41.81,P<0.05);风管内表面细菌总数、真菌总数、积尘量合格率为98.4%、89.5%、100.0%,各指标间差异有统计学意义(χ^(2)=20.42,P<0.05);冷却水中嗜肺军团菌检出率为10.5%。结论苏州市公共场所集中空调通风系统卫生状况总体较好,但真菌和军团菌污染需要加以关注。

Evolutionary model of the central place hierarchical system

Central place theory is one of the two theoretical cornerstones of geography, yet it cannot be connected with other spatial structure models, fails to provide definite time-space parameter conditions, lacks an evolutionary process model, and does not easily enable construction of a complete theoretical system of regional spatial structure. This paper gives an in-depth analysis of the process and mechanism for production and evolution of central places of different grades, and constructs an evolutionary model of the central place hierarchical system. The results of deduction, analysis and simulation show that production and evolution of the central place hierarchical system may be divided into five stages. These stages are the embryonic, formative, improvement, maturation, and advancement stages. Affected by spatial location and centricity, central places have obvious differences in scale and functional structures. There are great differences in the scale of same-grade central places. However, low-grade central places could have larger scales than high-grade central places, and the central places of a central location may form the agglomeration area of central places. Based on the hypothesis condition of an isotropic plain, the research shows that it is possible not only to form proportional functional structures of central places, but also to produce non-proportional scale structures of central places, and thus to complete the transformation from rationalistic deduction of spatial equilibrium mode to an explanation and demonstration of an unbalanced practical model.

基于图像识别的隧洞排尘控制系统分析

随着信息化、智能化、网络化的发展,计算机图像识别技术已在多数领域得到广泛应用。云南TB水电站在进行过坝隧洞通风及照明系统升级时,设计了一套基于图像识别的排尘控制系统,分析了系统的组成、网络、集中控制级、现地控制站和图像识别控制,探讨了图像识别的关键技术。

明清时期太湖流域的中心地结构

太湖流域是长江三角洲的核心组成部分。研究表明,该地区虽然水网密布,水系发达,并有太湖等大小湖泊存在,但并不影响中心地结构在该区域的形成,其形成机理是地形平坦、水系呈规则的圩田塘埔系统,及高度发达的市场体系。该中心地结构的中心城市是苏州,而苏州位于太湖流域的几何中心;另一方面,不同等级中心地的间距之间存在着高度的对应性。据此,根据太湖流域中心地的形成过程,可以给出以下的中心地结构的形成路径:区域几何中心决定最高等级中心地的区位;区域面积决定一级中心地与二级中心地之间及二级中心地之间的距离;高等级中心地之间的间距决定以后,余下的不同等级中心地之间的距离即可同时决定。由此,太湖流域中心地结构的形成体现了典型的自上而下的中心地形成过程与类型。这一形成过程具有一般性,即对任何一个中心地而言,都有一个自低等级中心地向高等级中心地的转化、升级过程,但对整个区域而言,却是高等级中心地首先形成,然后才是以此为中心各级不同等级中心地的相继形成,最终形成完整的中心地等级体系。其研究结论丰富与完善了中心地学说。

经济地域系统理论视角下的中心地及其扩散域

中心地理论与经济地域系统理论具有重要的理论契合与互馈,经济地域系统理论作为区域经济地理学的重要基础理论对理解和认识中心地系统具有重要的作用。分工与联系是经济地域系统理论和中心地理论的重要理论契合点,中心地系统无论是概念内涵还是运行机制都是属于经济地域系统的组成部分,具有经济地域的一般属性,同时具有动态性特征、等级性和尺度差异特征、圈层异质性与多向性特征、重叠与嵌套特征、再集聚特征等。中心地系统作为具有复杂性的地域经济系统,在条件变化下,会呈现出扩散域的重叠、嵌套、轮空、扩大、再集聚等多种空间层次变化特点。

基于可达性的沈阳经济区中心地空间结构演变

从影响城市与区域发展的交通因素入手,在其变化过程中探讨沈阳经济区中心地结构的演变。以可达性作为度量沈阳经济区交通因素优劣性的指标,通过对1992,2000和2011年3个时段的交通数据计算,得出沈阳经济区各中心地可达性,并通过可达性与中心地空间结构的叠加分析得出沈阳经济区各中心地的发展特征与演化趋势。研究表明:沈阳经济区中心地空间结构中心极化明显,内部圈层中心地体系完整,发达程度高,主要交通轴线上的中心地数量及规模发展较快。在交通因素主导下,可达性与中心地空间相互作用强烈,并引导中心地视图向点轴与圈层相融合的蛛网模式演变。

作为人居环境的中国城市群--空间格局与展望

城市群是国家推进新型城镇化的主体形态,同时也是主要的人居环境。从人居的角度来看,中国城市群的发展将受制于在相对狭小的宜居空间内集聚大规模人口的特殊国情,同时受到区域快速交通网络发展的影响。将城市群视为不同尺度空间之叠合,一是在国家/区域尺度上以快速交通网络为骨架的城市节点网络空间;二是在区域/地方尺度上以不同等级城市组成的中心地体系。基于"网络"与"中心地体系"的空间特征,提出了模拟城市群空间格局的"递归近邻搜索法",模拟了快速铁路网络条件下由3个世界级城市群、5个国家重点城市群、以及若干个区域性城市群组成的中国城市群新格局。对城市群的未来格局进行展望,并提出优化我国城市群的人居环境的建议,为新型城镇化进程中城市群规划和政策的制定提供借鉴和参考。

新疆旅游中心地等级体系初构

根据新疆旅游业发展现状与存在的问题,阐明了确定新疆旅游中心地的必要性。以旅游中心地概念及克里斯泰勒中心地理论为基础,针对新疆旅游业发展中存在的"瓶颈"——交通问题,分析计算了通达性指数与网尼克指数两个指标,结合新疆各地区的旅游景点和酒店数目,确定了新疆旅游中心城市(中心地)。利用以上四个指标进行聚类分析,划分了新疆旅游中心区域,从而初步构建了新疆旅游中心地等级体系。运用增长极理论进一步提出了新疆旅游中心地等级体系的布局模式。

基于可达性的中心地体系的空间分析

以克里斯泰勒的中心地理论为基础,以最短通行时间、加权平均出行时间作为可达性的评价指标,以基于GIS平台开发的可达性计算模块为技术支撑,从空间可达性、空间相互作用、空间服务范围几个方面对均质背景和交通背景下的中心地体系进行空间分析,探讨中心地体系的空间演化及空间重构,以期对中心地体系的过程模拟和空间表达进行初步探索性的尝试。结果表明:均质背景下,次一级中心地产生于上一级中心地可达时间最长的地方;基于加权平均出行时间的可达性在同等级的中心地间出现了差异,相同等级的中心地越是靠近高等级中心地,其加权平均出行时间越短,由于中心地相对区位的不同,同一等级的中心地之间出现了差异增长,其结果会形成连续的中心地等级。伴随着交通网络的演进,中心地空间结构进入由"点-轴-网"构成的全面有组织的均衡发展阶段。

湖北省旅游中心地空间结构系统优化研究

旅游中心地作为区域旅游的旅游目的地、客源供给地、旅游集散地和旅游服务中心,对区域旅游的发展有着至关重要的意义。研究旅游中心地的空间结构,分析旅游中心地空间结构系统的优化对策,是推动区域旅游业进一步发展的必然要求。文章介绍了旅游中心地的概念和界定方法,分析了湖北省旅游中心地空间结构的现状和系统构建途径及优化措施。

中心地理论与聚落体系规划──以苏州工业园区中心村建设规划为例

论文从评介克氏中心地理论入手，分析了中心地理论对区域聚落体系规划的重要意义。通过对苏州工业园区中心村建设的典型案例研究，论文表明只要实际条件与理论假设基本符合，其理想模式就能在区域规划中直接运用。论文最后简要分析了中心地理论在聚落体系规划中的应用前景和发展方向。

河北省公共场所集中空调风管系统污染调查

目的了解河北省公共场所集中空调通风系统微生物污染状况。方法按卫生部《公共场所集中空调通风系统卫生规范》及实施指南的采样和检测方法,抽取河北省5个省辖市63家公共场所的集中空调通风系统,检测通风系统的风管积尘量及积尘中细菌总数、真菌总数及冷却塔水、冷凝水中的军团菌。结果5个城市31家公共场所集中空调风管系统均为严重污染。5个城市集中空调通风系统风管积尘中真菌总数均为严重污染;管道积尘量中等污染率为61.9%;积尘中细菌总数严重污染率为81.9%。32家公共场所的集中空调冷却水、冷凝水中检出3株军团菌。结论本次调查的河北省公共场所集中空调通风系统微生物污染严重,不存在地域性差异。不同种类的公共场所集中空调风管系统细菌总数污染的严重程度有差异。

深圳市福田区公共场所集中空调系统卫生状况分析

目的了解深圳市公共场所集中空调系统卫生状况,为卫生管理提供依据。方法对6家医院和6家旅店集中空调系统的卫生管理状况进行调查,按《公共场所集中空调通风系统卫生管理办法》、《公共场所集中空调通风系统卫生规范》要求进行采样和检测。结果 12家单位共38套通风系统中送风空气PM10合格率为92.1%(35/38),细菌总数的合格率为83.7%(159/190),真菌总数合格率为89.5%(170/190),β-溶血性链球菌等致病菌均未检出;风管表面积尘量合格率为86.8%(33/38),细菌总数合格率为100%(276/276),真菌总数合格率为98.9%(273/276),致病菌均未检出;空调冷凝水嗜肺军团菌合格率为100%(29/29),空调冷却水嗜肺军团菌合格率为71.4%(25/35)。结论深圳市福田区公共场所集中空调通风系统送风空气有污染,冷却塔嗜肺军团菌检出率较高,已对人群健康构成一定威胁,应加大监督管理力度,加强集中空调通风系统各环节的清洁和消毒工作。

武汉市公共场所空调冷却塔军团菌污染现状调查研究

目的掌握武汉市公共场所集中空调通风系统军团菌污染现状,为预防空气传播疾病,加强该系统的规范管理提供科学依据。方法应用分层抽样和随机抽样相结合的方法抽取样品进行检测。采用EpiData进行数据录入,用SPSS 12.0进行统计学分析。结果在抽检的70个空调冷却塔中军团菌检出32个,检出率为45.71%,商场超市与宾馆酒店间的军团菌污染状况无统计学差异(P>0.05)。在军团菌检出的亚型中,以长滩型为主,占40.63%;其次为LP1型(28.13%)和LP6型(25.00%)。结论该市公共场所集中空调通风系统军团菌污染严重,应当引起相关卫生部门的重视,应制定防止军团菌污染的干预措施,防止空气传播性疾病的传播。