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1.
According to Christopher Alexander’s theory of centers, a whole comprises numerous, recursively defined centers for things or spaces surrounding us. Wholeness is a type of global structure or life-giving order emerging from the whole as a field of the centers. The wholeness is an essential part of any complex system and exists, to some degree or other, in spaces. This paper defines wholeness as a hierarchical graph, in which individual centers are represented as the nodes and their relationships as the directed links. The hierarchical graph gets its name from the inherent scaling hierarchy revealed by the head/tail breaks, which is a classification scheme and visualization tool for data with a heavy-tailed distribution. We suggest that (1) the degrees of wholeness for individual centers should be measured by PageRank (PR) scores based on the notion that high-degree-of-life centers are those to which many high-degree-of-life centers point, and (2) that the hierarchical levels, or the ht-index of the PR scores induced by the head/tail breaks, can characterize the degree of wholeness for the whole: the higher the ht-index, the more life or wholeness in the whole. Three case studies applied to the Alhambra building complex and the street networks of Manhattan and Sweden illustrate that the defined wholeness captures fairly well human intuitions on the degree of life for the geographic spaces. We further suggest that the mathematical model of wholeness be an important model of geographic representation, because it is topological oriented, which enables us to see the underlying scaling structure. The model can guide geodesign, which should be considered as the wholeness-extending transformations that are essentially like the unfolding processes of seeds or embryos, for creating built and natural environments of beauty or with a high degree of wholeness.  相似文献   

2.
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3.
A fractal can be simply understood as a set or pattern in which there are far more small things than large ones, for example, far more small geographic features than large ones on the earth surface, or far more large-scale maps than small-scale maps for a geographic region. This article attempts to argue and provide evidence for the fractal nature of maps and mapping. It is the underlying fractal structure of geographic features, either natural or man-made, that make reality mappable, large-scale maps generalizable, and cities imageable. The fractal nature is also what underlies the beauty of maps. After introducing some key fractal concepts such as recursion, self-similarity, scaling ratio, and scaling exponent, this article demonstrates that fractal thought is rooted in long-standing map-making practices such as series maps subdivision, visual hierarchy, and Töpfer’s radical law. Drawing on previous studies on head/tail breaks, mapping can be considered a head/tail breaks process; that is to divide things around an average, according to their geometric, topological and/or semantic properties, into the head (for those above the average) and the tail (for those below the average), and recursively continue the dividing process for the head for map generalization, statistical mapping, and cognitive mapping. Given the fractal nature of maps and mapping, cartography should be considered a perfect combination of science and art, and scaling must be formulated as a law of cartography or that of geography in general.  相似文献   

4.
流域水文模型中的土壤质地转换与饱和导水率Ks值确定   总被引：1，自引：0，他引：1  
构建于GIS基础之上的分布式水文模型,近年来得到了普遍的应用和较快的发展。土壤质地数据是模型构建的重要参数,但实际运用中,常存在土壤数据多种统计口径并存、与模型运算所需的数据类型不一致等问题,限制了模型的应用和模拟的精度。根据土壤典型剖面值,利用3次样条函数曲线插值得出了模型所需土壤粒径分布。根据粒径组成,使用NeroTheta软件计算出饱和导水率凡值。为构建分布式水文模型数据库,确定主要土壤参数提供了简便有效的方法。  相似文献   

5.
Hispanic Community Types and Assimilation in Mex-America   总被引：1，自引：0，他引：1  
I argue that discrepancies among Hispanic assimilation models can be interpreted through three distinct types of Hispanic communities—continuous, discontinuous, and new. Continuous communities were founded by Hispanics and Hispanics have always been the majority population. As a result, Hispanics have not assimilated as predicted by traditional models. Discontinuous communities were originally settled by Hispanics, but eventually were filled by a minority population. Since WWII, many of these communities have experienced a Hispanic demographic resurgence making assimilation more problematic. Hispanics in new communities are recent immigrants to Anglo dominant communities and are more apt to follow the traditional assimilation model.  相似文献   

6.
中国城市规模划分新标准的适用性研究   总被引：6，自引：0，他引：6  
2014年11月,国务院发布《关于调整城市规模划分标准的通知》,将城市规模等级划分为“五类七档”,受到广泛关注。但因对新标准的理解存在歧义而出现各种划分结果,引起误解与混乱。在对比新旧标准的基础上,以第六次人口普查数据为基础,分析2010年中国城市规模等级结构,评价新标准的科学性和局限性。结果显示,新标准在空间口径、人口口径、分级标准等方面进行了实质性的改进;按照新标准划分的2010年中国城市规模等级结构,相对于旧标准及其他标准而言,特大城市和大城市数量大幅缩减,而中小城市数量相应增多,呈现出显著的金字塔结构特征,更加符合中心地理论模型和位序—规模法则,更有利于科学地实施城市与人口的分类管理。但同时,新标准也存在“城区人口”数据难以获取、受行政区划调整影响较大等局限性,亟待加强实体城区识别研究和推进数据共享。  相似文献   

7.
Observations assigned to any two classes in a choropleth map are expected to have attribute values that are different. Their values might not be statistically different, however, if the data are gathered from surveys, such as the American Community Survey, in which estimates have sampling error. This article presents an approach to determine class breaks using the class separability criterion, which refers to the levels of certainty that values in different classes are statistically different from each other. Our procedure determines class breaks that offer the highest levels of separability given the desired number of classes. The separability levels of all class breaks are included in a legend design to show the statistical likelihood that values on two sides of each class break are different. The legend and the associated separability information offer map readers crucial information about the reliability of the spatial patterns that could result from the chosen classification method.  相似文献   

8.
《Urban geography》2013,34(1):91-94
This study disentangles the relationship between income and real estate value development in Dutch urban neighborhoods. Within the literature on upgrading and downgrading, it is often assumed that neighborhood income and real estate value development are strongly linked. The results reported here—based on research in Amsterdam, The Hague, and Tilburg—indicate that income and real estate values develop simultaneously in only a relatively small number of neighborhoods, which are at the top and bottom of the housing market hierarchy. The majority reveal a more complex relationship: a number of neighborhoods show a time lag between the trends, whereas in other neighborhoods income and real estate values show partially diverging trends. Several tentative explanations are offered for the complex relationship, and stress the importance of place-specific knowledge. Three points of attention are suggested for further research: understanding the role of household dynamics, the position of neighborhoods within their urban system, and the role of the state and housing associations in neighborhood change.  相似文献   

9.
Urban streets are hierarchically organized in the sense that a majority of streets are trivial, while a minority of streets is vital. This hierarchy can be simply, but elegantly, characterized by the 80/20 principle, i.e. 80% of streets are less connected (below the average), while 20% of streets are well connected (above the average); out of the 20%, there is 1% of streets that are extremely well connected. This paper, using a European city as an example, examined, at a much more detailed level, such street hierarchies from the perspective of geometric and topological properties. Based on an empirical study, we further proved a previous conjecture that a minority of streets accounts for a majority of traffic flow; more accurately, the 20% of top streets accommodate 80% of traffic flow (20/80), and the 1% of top streets account for more than 20% of traffic flow (1/20). Our study provides new evidence as to how a city is (self‐)organized, contributing to the understanding of cities and their evolution using increasingly available mobility geographic information.  相似文献   

10.
Recent decades have seen substantial growth across many developed-world countries of right-wing populist political parties whose policies oppose immigration and multiculturalism as threats to the majority way of life there. These are exemplified in Australia by Pauline Hanson’s One Nation Party, which was successful at elections there at the turn of the twenty-first century and again in 2016. Part of this party’s rhetoric focuses on the geography of immigrant groups in Australia’s cities, with claims that their members live in ghettos. Is that factually correct? Using data from the 2011 Australian census this paper analyses the distribution of Asians and Muslims (the two groups picked out by One Nation and its leader) at four spatial scales within the country’s 11 largest urban areas. It finds no evidence at all of intensive residential segregation of Muslims, and although there are concentrations of Asians—notably in Sydney and Melbourne—most residents claiming Asian ancestry live in neighbourhoods and suburbs where they form a minority (in many cases a small minority) only of the local population.  相似文献   

11.
土地类型研究的意义、功能与学科发展方向   总被引：3，自引：1，他引：2  
申元村 《地理研究》2010,29(4):575-583
土地类型是综合自然地理学的基本研究对象,反映的是中小尺度地段分异规律和综合整体的环境特征。对土地类型研究的学术意义、功能和对未来学科发展方向进行界定,对促进土地类型学的发展和应用功能的发挥有重要作用。文章总结了土地类型研究的学术意义与功能,认为土地类型研究是自下而上论证综合自然区划、确立区域土地结构、进行生态研究和生态建设设计、进行农林牧合理用地布局和用地结构调整、灾害成因和防灾减灾研究的基础性学科;在分析国内外研究现状与问题的基础上,指出当前该学科存在的关键学术问题是土地类型划分的基本分级体系不确定,各级土地类型划分指标体系未建立,遥感与多元数据计算机制图与分类指标体系未实现技术连接;从学科发展方向着眼,当前应通过遥感、地理信息系统与野外考察相结合,通过典型区解剖方法,确立土地类型基本分级体系,建立各级类型划分指标,以及遥感与多元数据计算机制图与分类指标体系的技术连接,并对未来需要研究的课题作了展望。  相似文献   

12.
This article examines the former location-based social medium Brightkite, over its three-year life span, based on the concept of natural cities. The term natural cities refers to spatially clustered geographic events, such as the agglomerated patches aggregated from individual social media users’ locations. We applied the head/tail division rule to derive natural cities, based on the fact that there are far more low-density areas than high-density areas on the Earth's surface. More specifically, we generated a triangulated irregular network, made up of individual unique user locations, and then categorized small triangles (smaller than an average) as natural cities for the United States (mainland) on a monthly basis. The concept of natural cities provides a powerful means to develop new insights into the evolution of real cities, because there are virtually no data available to track the history of cities across their entire life spans and at very fine spatial and temporal scales. Therefore, natural cities can act as a good proxy of real cities, in the sense of understanding underlying interactions, at a global level, rather than of predicting cities, at an individual level. Apart from the data produced and the contributed methods, we established new insights into the structure and dynamics of natural cities; for example, the idea that natural cities evolve in nonlinear manners at both spatial and temporal dimensions.  相似文献   

13.
Government agencies striving to make geospatial information systems interoperable and cost‐effective often appear to function as a self‐regulating network shaped only by internal trust and reciprocity. However, recent public management research suggests that external steering of a network, exercised by authoritative bodies through hierarchical means, may invigorate cross‐agency coordination. The two case studies of federal geospatial coordination in Canada and the USA confirm this emerging theory of network–hierarchy dynamics. In these countries, the central budget agency (CBA) is influencing resource flows and accountabilities within a federal geospatial network of government agencies, which in turn affects how these agencies deliver ‘joined up’ services. The CBA relies upon three types of tools: the shaping of network governing structures, promotion of uptake of new management information systems, and the use of evaluation (scrutiny) to solidify accountabilities of the network. Since these tools cast a shadow of hierarchy upon the network, they may be viewed as counter to the voluntary ethos of networks. However, the case studies suggest that the CBA's actions appear to confer legitimacy to the network—resulting in a seeming contradiction—greater central control, more vigorous, distributed geospatial coordination.  相似文献   

14.
球粒是球粒陨石的主要组分,目前球粒分类体系主要有三种,即结构分类、FeO-SiO2分类和M-FeO-CaO分类。球粒结构分类过于依赖结构与形态,而与化学成分联系不紧密。FeO-SiO2分类体系和M-FeO-CaO分类体系在传统的结构分类体系基础上加入了矿物化学分类参数,这有利于进一步研究太阳星云演化的物理化学过程。但与结构分类相比,很少利用FeO-SiO2和M-FeO-CaO分类体系对陨石球粒进行分类。本次所研究陨石为我国新发现的沙漠陨石富集区——新疆库木塔格沙漠004号陨石（L4,S4,W3）,在对其中的球粒进行了详细普查和研究的基础上,分别利用三种分类体系对该陨石中的球粒进行分类,并进一步探讨了FeO-SiO2分类和M-FeO-CaO分类方法优缺点与应用范围。通过对比分析,提出了后两种分类方法的改进意见：针对FeO-SiO2分类体系,提出以硅酸盐中FeO=7.5%（wt%）为I型和II型球粒分界线,SiO2=47%及53%（wt%）为A型、AB型和B型球粒分界线。FeO-SiO2分类体系不仅能应用于斑状球粒,也适用非斑状球粒。对M-FeO-CaO分类体系依据辉石组分（FeO及CaO,单位wt%）对A1型（FeO＜1,CaO＞1）、A2型（FeO≈1—3,CaO＜0.5）、A5型（FeO≈11—14,CaO≈0.3—0.9）和B型（FeO＞3,CaO＜0.5）球粒的类型区间进行了初步划分。  相似文献   

15.
The present study examined and compared spatio–temporal interaction of the theft of car parts, shop burglary and motorcycle theft in the central business district (CBD) of the city of Zanjan in Iran. The Knox test was selected to detect spatio–temporal interaction. This test has been criticized as being subjective because the selection of critical distances is arbitrary; thus, a method is proposed to detect critical distances in the Knox test using the mean distance, natural breaks classification of nearest neighbour (NN) distance and Ripley’s k function. Results show obvious differences between the spatio-temporal clusters of the three sets of crimes. They also indicate that changing the spatial cut-offs within a cluster creates different temporal patterns. Of the three criteria for determining critical distances, NN classification based on natural breaks showed more interactions than the other methods.  相似文献   

16.
There are nearly 700 cities in China, each with their own particular characteristics of natural environment quality and rates of economic development. When people are able to choose a city to live in, they will take into account these characteristics in order to improve their lifestyles. Based on geographic information system technology and the analytic hierarchy process method, a model of the living environment suitability index (LESI) for the larger cities of China was designed. The LESI was constructed by using the factors of economic condition, convenience and livable degree, natural environment and natural resources. The LESI model was then applied to compare the living conditions in 35 major cities in China in 2007, including 30 provincial capitals and 5 sub-provincial cities. LESI values were higher for cities in southeast China than for cities in the northwest. The highest LESI values were mainly distributed along the Chinese southeast coast and the Yangtze River Delta. Cities with the lowest LESI values were found in the centre and north of China. Of the 35 cities, 4 had highly suitable living environments and 7 had unsuitable living environments.  相似文献   

17.
Accurate estimation of evapotranspiration(ET),especially at the regional scale,is an extensively investigated topic in the field of water science. The ability to obtain a continuous time series of highly precise ET values is necessary for improving our knowledge of fundamental hydrological processes and for addressing various problems regarding the use of water. This objective can be achieved by means of ET data assimilation based on hydrological modeling. In this paper,a comprehensive review of ET data assimilation based on hydrological modeling is provided. The difficulties and bottlenecks of using ET,being a non-state variable,to construct data assimilation relationships are elaborated upon,with a discussion and analysis of the feasibility of assimilating ET into various hydrological models. Based on this,a new easy-to-operate ET assimilation scheme that includes a water circulation physical mechanism is proposed. The scheme was developed with an improved data assimilation system that uses a distributed time-variant gain model(DTVGM),and the ET-soil humidity nonlinear time response relationship of this model. Moreover,the ET mechanism in the DTVGM was improved to perfect the ET data assimilation system. The new scheme may provide the best spatial and temporal characteristics for hydrological states,and may be referenced for accurate estimation of regional evapotranspiration.  相似文献   

18.
In this paper, we propose a new method for detecting outliers in an irregularly distributed spatial data set. Our method has two desirable properties. First, it is functionally effective due to the introduction of sensitive outlier indices and locally adaptive and robust statistical criteria. Second, it is computationally efficient because of the use of super-block based spatial data sorting and searching scheme. Our method has been implemented using the C programming language and integrated with the Arc/Info GIS system. The integration leads to a powerful exploratory data analysis tool for checking and analysing anomalous values in a GIS environment. Local outliers can be automatically labeled with our method, subject to some user-defined parameters. Outliers represent anomalous or suspicious values in a statistical sense, which may not necessarily be erroneous values. Instead of being simply discarded, statistical outliers should be investigated further using prior qualitative knowledge or in association with other GIS data layers.  相似文献   

19.
The most common goal when classing data for choropleth maps is to create homogeneous classes which contain similar data values. None of the four traditional data classing methods examined here (quartile, equal interval, standard deviation, and natural breaks) consistently generalized the experimental data sets into homogeneous classes. These methods were most accurate for data sets with specific distributional characteristics, but none classed all of any type of distribution accurately. Only the optimization method produced reliable and accurate results for all of the experimental data.  相似文献   

20.
Shape characterisation is important in many fields dealing with spatial data. For this purpose, numerous shape analysis and recognition methods with different degrees of complexity have so far been developed. Among them, relatively simple indices are widely used in spatial applications, but their performance has not been investigated sufficiently, particularly for building footprints (BFs). Therefore, this article focuses on BF shape characterisation with shape indices and classification schemes in a GIS environment. This study consists of four phases. In the first phase, the criteria for BF shape complexity were identified, and accordingly, benchmark data was constructed by human experts in three shape complexity categories. In the second phase, 18 shape indices were selected from the literature and automatically computed in GIS. The performance of these indices was then statistically assessed with histograms, correlation matrix and boxplots, and consequently four indices were found to be appropriate for further investigation. In the third phase, two new indices (Equivalent Rectangular index and Roughness index) were proposed with the objective to measure some BF shape characteristics more efficiently. The proposed indices also were found to be appropriate with the same statistical assessment procedures. In the final phase, BF shape complexity categories were created with the pairs of six appropriate indices and four choropleth mapping classification schemes (equal intervals, natural break, standard deviation, and custom) in GIS. The performance of the index–scheme pairs was assessed against the benchmark data. The findings demonstrated that both new indices and two of the selected indices (Convexity and Rectangularity) delivered higher performance. The custom classification scheme was found more ideal to reveal absolute shape complexity with the index value ranges derived from the boxplots while the other classification schemes were more appropriate to reveal relative shape complexity.  相似文献   

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