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1.
《The Professional geographer》2013,65(2):189-193
A population density model is presented for urban areas containing multiple centers. Utilities of this model include evaluating time series for a transformation from monocentricity to polycentricity and testing the assumption of monocentricity at any point in time. Following a discussion of the method of calibrating this model, a case study of Toronto is presented. The major finding from 1971 and 1976 Toronto data is that no transformation is yet detectable. Interpretation of the model is exemplified in this empirical exercise. 相似文献
2.
Relatively little research has explored spatial structure in modern major Canadian regions. Three common models are monocentricity, polycentricity, and dispersion, but these are not always mutually exclusive in the complex spatial structures of contemporary city-regions. Shifts between these models are discussed in the context of three explanations of economic growth and restructuring: accessibility, municipal competition, and globalization. All three explanations suggest a trend away from monocentricity. While this appears clearly in US cities, disagreement surrounds whether Canadian cities are following the same path. This study uses cross-sectional data from InfoGroup in 2011 to estimate the relative strengths of monocentricity, polycentricity, and dispersion for characterizing eight major regions. Results indicate that elements of each model are evident in all eight study regions, but each tends to dominate in different contexts. When focusing on Montreal, Toronto, and Vancouver, results imply that all three forces which guide spatial structure play a role and that job centers appear to play a particularly important structural role in larger regions. 相似文献
3.
Employment and population spatial structure of metropolitan regions have evolved in the era of post-industrialization. Empirical and theoretical debates have consensus that monocentric model is no longer explaining the phenomenon of population and employment distribution. One argument regards polycentricity as a permanent spatial structure beyond monocentricity; another idea believes that dispersion can explain spatial variation of employment and population too. This study investigated the level of monocentricity and primacy of principal city in Tehran Metropolitan Region (TMR), in addition to sub-centering and level of polycentrism. Dispersion of employment and population in TMR was also analyzed. The results revealed that standard monocentric model is not able to explain evolution of Tehran although it is dominant core of the region. The polycentric models illustrated that although the changes from 2006 to 2011 were not considerable, employment was more concentrated than population; they also showed that there is no distinction between polycentric and dispersion and regions may have some levels of polycentricity and dispersion. 相似文献
4.
The typology of the American metropolis: monocentricity,polycentricity, or generalized dispersion? 总被引：1，自引：1，他引：0
Although the spatial structure of employment in large US metropolitan regions is a well-researched topic, few studies focus on medium-sized and small US metropolitan regions. Consequently, there is no overall typology relating small-to-medium urban form to employment distribution. We address this gap by investigating the spatial structure of employment in 356 metropolitan regions. We conceptualize six typologies based on three categories that have overlapping properties: “monocentricity,” “polycentricity,” and “generalized dispersion.” The study has three main findings. First, the three types of urban form that we identify as “hybrid” outnumber the three “pure” types by almost four to one. Second, job dispersion is a dominant characteristic in almost 70% of all metropolitan statistical areas (MSAs) (including the hybrid types), and polycentricity (56.7% of MSAs) is somewhat more common than monocentricity. Third, there is a strong relationship between population size and density. The population of medium-sized metropolitan areas is generally more dispersed than that of small and large metropolitan areas. Polycentricy emerges mostly in large metropolitan regions, while monocentrity is found in both small and large metropolitan regions. 相似文献
5.
M. Tenney G. Brent Hall R. E. Sieber 《International journal of geographical information science》2019,33(8):1497-1519
This paper presents a crowd sensing system (CSS) that captures geospatial social media topics and allows the review of results. Using Web-resources derived from social media platforms, the CSS uses a spatially-situated social network graph to harvest user-generated content from selected organizations and members of the public. This allows ‘passively’ contributed social media-based opinions, along with different variables, such as time, location, social interaction, service usage, and human activities to be examined and used to identify trending views and influential citizens. The data model and CSS are used for demonstration purposes to identify geotopics and community interests relevant to municipal affairs in the City of Toronto, Canada. 相似文献
6.
《Urban geography》2013,34(6):497-520
This paper examines the search behavior of a sample of Portuguese and Canadian-born homebuyers in suburban Toronto, Canada. Attention is focused on the extent to which Portuguese homebuyers rely upon real estate agents from the same ethnic background and how this source can influence the homebuyer's housing search and ultimate choice of a residence. Data were obtained from a questionnaire survey that was administered to a sample of 110 Portuguese and 90 Canadian-born recent homebuyers in the city of Mississauga, a western suburb of Toronto. All were nonresidents of Mississauga at the time of purchasing the house. The evidence indicates that Portuguese homebuyers differ significantly from the Canadian-born in their housing search by relying more extensively on ethnic sources of information, particularly real estate agents from the same ethnic background. However, almost equal numbers of Portuguese purchased houses in Portuguese and non-Portuguese neighborhoods in Mississauga. In this respect, the evidence suggests that Portuguese realtors play a more limited role in reinforcing existing spatial patterns of Portuguese settlement in Mississauga. 相似文献
7.
《Urban geography》2013,34(4):375-396
This research investigates the evolution of the system of Canadian decision-making centers using the location of corporate board members as a surrogate for the location of economic control. The major premise examined by this study states that, through much of the study period, board linkages should tend to concentrate on Toronto, Canada's dominant corporate administration center. While Toronto gains importance, Montreal loses connections, devolving from close competition with Toronto for national influence to become a major regional center for Quebec. At the same time, cities in other parts of the country gain importance as they evolve into major centers for their region. The result of these changes is the emergence of a dominant national center, along with a second tier of cities of regional importance. The results of the board member analysis reveal that the economy as a whole increasingly concentrates control in Toronto through the 1970s and 1980s. Montreal loses director connections with the rest of the country through the same period. While the economy as a whole centralizes in Toronto, certain sectors of the economy decentralize their directors to regional centers. Calgary, in particular, emerges as a major regional center for western Canada. The paper relates these observations to the dual conceptual frameworks of quaternary location theory and the resource dependence perspective. 相似文献
8.
《Urban geography》2013,34(5):466-486
This paper focuses on some of the main technological associations which exist between small manufacturing firms and specialist units in the producer services. It is argued that knowledge-intensive inputs from external consultants play a major enabling role in local industrial innovation. Empirical evidence from a stratified sample of Toronto manufacturers is used to illustrate the scale, nature, and effects of current linkage arrangements. Survey data are presented which indicate that small industrial firms deliver substantial streams of income to local consultants. A major finding of the survey is that technical service inputs assist the export and innovation objectives of small Toronto firms. 相似文献
9.
基于Multi-Agent System的多尺度土地利用变化模型的构建与模拟 总被引：7，自引：0，他引：7
通过土地利用情景变化模型反映多尺度的土地利用现象,是学者们研究的焦点问题。本文基于MAS理论,构建从地块到村庄的多尺度土地利用变化模型,揭示微观层面不同尺度上土地利用变化的机制。应用该模型,以陕西省米脂县孟岔村为例进行研究,定量分析该村农户个体、农户群体和农户整体等不同尺度上的土地利用决策,并通过与2008年实际土地利用变化数据对比和分析,对构建的多尺度土地利用变化模型进行检验。通过分析,认为:(1)基于MAS的多尺度农户土地利用变化模型可较好地反映微观土地利用决策和空间的多尺度变化;(2)构建用 连续数值表示的农户土地利用决策与实际状况比较符合;(3) 本文为不同农户群体间的转化方法、农户间相互作用,以及市场与政策因素的作用等方面的研究打下坚实的基础。 相似文献
10.
定量遥感尺度转换方法研究进展 总被引：3，自引：0，他引：3
首先对遥感科学和气象学、水文学、生态学、地理学和的尺度概念及其转换方法进行了区分。其次对遥感数据空间尺度转换方法的国内外研究进展情况进行了系统梳理,重点比对了目前空间尺度转换常用6种转换方法：统计转换法、分类转换法、数据融合转换方法、分形分析法、基于局域动态模型的转换方法和基于物理意义尺度转换方法及其各自所属方法的优点和缺点。再次以遥感时间尺度转换应用最为广泛的地表蒸散发和农业旱情监测等2个领域为例,对遥感时间尺度转换方法进行了总结。最后预测了今后定量遥感尺度转换研究可能的研究重点,以期为今后更好地开展尺度效应和尺度转换研究工作提供参考。 相似文献
11.
In this article, we use parcel-based land-use data to analyze 50 years of residential development in the Toronto region. We test two hypotheses: (1) Toronto’s form does not conform to conventional definitions of suburban sprawl and (2) Toronto’s suburban development shows high levels of continuity over time with relatively high densities and mixed housing types. Contrary to recent research suggesting a convergence of urban forms among North American metropolitan regions, Ontario’s robust planning system has created a distinctive, highly consistent pattern of residential development that has, for half a century, achieved many of the core goals of smart growth including relatively compact, contiguous, and concurrent development. This form continues to be automobile dependent, however, and is not producing many of the benefits ascribed to smart growth. Rather than continuing to adopt United States-inspired smart growth policies, a more ambitious set of initiatives will be required to address current regional challenges. 相似文献
12.
13.
This study analyzes metropolitan dynamics in a small country with an “island state” context of closed boundaries, using commuting data and mobile phone tracking data. We examine whether the Israeli context encourages the formation of a monocentric “metropolitan state,” characterized by increasing links between localities throughout the country and its principal metropolitan node (Tel Aviv)—rather than with secondary metropolitan areas—and by fuzzy, overlapping metropolitan boundaries. Commuting data from the 1995 and 2008 censuses show that metropolitan expansion processes in Israel are gradual. Mobile phone tracking data for 2013 reveal similar patterns, confirming the urban structure’s stability and the reliability of tracking data as a means of assessing metropolitan processes. The “island state” context supports growing monocentricity, but, when it comes to commuting and travel for other purposes, Israel is not yet a metropolitan state; metropolitan boundaries are not as fuzzy and rapidly changing as expected. 相似文献
14.
A new statistical approach to the alignment of time series 总被引：1，自引：0，他引：1
Summary. Much research in the Earth Sciences is centred on the search for similarities in waveforms or amongst sets of observations. For example, in seismology and palaeomagnetism, this matching of records is used to align several series of observations against one another or to compare one set of observations against a master series. This paper gives a general mathematical and statistical formulation of the problem of transforming, linearly or otherwise, the time-scale or depth-scale of one series of data relative to another. Existing approaches to this problem, involving visual matching or the use of correlation coefficients, are shown to have several serious deficiencies, and a new statistical procedure, using least-squares cubic splines, is presented. The new method provides not only a best estimate of the 'stretching function' defining the relative alignment of the two series of observations, but also a statement, by means of confidence regions, of the precision of this transformation. The new procedure is illustrated by analyses of artificially generated data and of palaeomagnetic observations from two cores from Lake Vuokonjarvi, Finland. It may be applied in a wide variety of situations, wherever the observations satisfy the general underlying mathematical model. 相似文献
15.
Bofeng Li Yunzhong Shen Xingfu Zhang Chuang Li 《International journal of geographical information science》2013,27(8):1572-1592
Affine transformation that allows the axis-specific rotations and scalars to capture the more transformation details has been extensively applied in a variety of geospatial fields. In tradition, the computation of affine parameters and the transformation of non-common points are individually implemented, in which the coordinate errors only of the target system are taken into account although the coordinates in both target and source systems are inevitably contaminated by random errors. In this article, we propose the seamless affine error-in-variables (EIV) transformation model that computes the affine parameters and transforms the non-common points simultaneously, importantly taking into account the errors of all coordinates in both datum systems. Since the errors in coefficient matrix are involved, the seamless affine EIV model is nonlinear. We then derive its least squares iterative solution based on the Euler–Lagrange minimization method. As a case study, we apply the proposed seamless affine EIV model to the map rectification. The transformation accuracy is improved by up to 40%, compared with the traditional affine method. Naturally, the presented seamless affine EIV model can be applied to any application where the transformation estimation of points fields in the different systems is involved, for instance, the geodetic datum transformation, the remote sensing image matching, and the LiDAR point registration. 相似文献
16.
Carlos Teixeira 《The Professional geographer》1995,47(2):176-183
This study concerns the behavior and practices of real estate agents in the housing search process. The research investigates whether the information provided and houses recommended by agents working for Portuguese firms differ from the recommendations of agents working for firms owned by non-Portuguese brokers in the cities of Toronto and Mississauga (a western suburb of Toronto), Canada. Data for the study were obtained from a participant observation study of a sample of real estate agents. Empirical evidence indicates that the ethnicity of real estate agents (Portuguese versus non-Portuguese) and the brokers for whom they work (Portuguese-owned firms versus non-Portuguese-owned firms) determine to a considerable extent the marketing strategies of agents and the neighborhoods they recommend. 相似文献
17.
单一景观类型时空变化分析方法——以酒泉盆地绿洲化为例 总被引：1，自引：0，他引：1
受单一土地利用动态度模型的启发, 本文提出了格网化单一景观类型变化率模型, 较好地反映了单一景观类型在研究时段内的变化情况。在此基础上又提出累积变化率和时空变化指数模型, 用于描述单一景观类型在长时间序列中的空间变化, 并以中国西部酒泉盆地1963-2009 年间的绿洲化过程为例对模型进行了检验。结果表明:①格网化单一景观类型变化率模型, 可以很好地反映期初和期末单一景观类型的局部细微变化, 包括变化速度和空间分布情况;②累积变化率综合了中间各期数据的影响, 可以较好地刻画较长时间序列中单一景观类型的变化幅度及其空间分布情况;③时空变化指数能够反映单一景观类型的变化模式, 进一步描述了变化过程的特点和趋势;④3 个模型的综合运用, 可对单一景观类型的时空变化过程及其特征做出比较全面的描述和刻画。 相似文献
18.
Constraining basin thermal history and petroleum generation using palaeoclimate data in the Piceance Basin,Colorado 
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下载免费PDF全文 Yao Tong Daniel E. Ibarra Jeremy K. Caves Tapan Mukerji Stephan A. Graham 《Basin Research》2017,29(4):542-553
Careful assessment of basin thermal history is critical to modelling petroleum generation in sedimentary basins. In this paper, we propose a novel approach to constraining basin thermal history using palaeoclimate temperature reconstructions and study its impact on estimating source rock maturation and hydrocarbon generation in a terrestrial sedimentary basin. We compile mean annual temperature (MAT) estimates from macroflora assemblage data to capture past surface temperature variation for the Piceance Basin, a high‐elevation, intermontane, sedimentary basin in Colorado, USA. We use macroflora assemblage data to constrain the temporal evolution of the upper thermal boundary condition and to capture the temperature change with basin uplift. We compare these results with the case where the upper thermal boundary condition is based solely upon a simplified latitudinal temperature estimate with no elevation effect. For illustrative purposes, 2 one‐dimensional (1‐D) basin models are constructed using these two different upper thermal boundary condition scenarios and additional geological and geochemical input data in order to investigate the impact of the upper thermal boundary condition on petroleum source rock maturation and kerogen transformation processes. The basin model predictions indicate that the source rock maturation is very sensitive to the upper thermal boundary condition for terrestrial basins with variable elevation histories. The models show substantial differences in source rock maturation histories and kerogen transformation ratio over geologic time. Vitrinite reflectance decreases by 0.21%Ro, source rock transformation ratio decreases 10.5% and hydrocarbon mass generation decreases by 16% using the macroflora assemblage data. In addition, we find that by using the macroflora assemblage data, the modelled depth profiles of vitrinite reflectance better matches present‐day measurements. These differences demonstrate the importance of constraining thermal boundary conditions, which can be addressed by palaeotemperature reconstructions from palaeoclimate and palaeo‐elevation data for many terrestrial basins. Although the palaeotemperature reconstruction compiled for this study is region specific, the approach presented here is generally applicable for other terrestrial basin settings, particularly basins which have undergone substantial subaerial elevation change over time. 相似文献
19.
Gerald M. Barber 《The Professional geographer》1978,30(2):149-155
The transportation requirements of an urban area are, in part, a function of its land use pattern. Reducing travel in an urban area by effective land use design appears to be a worthwhile public policy objective. The planning model derived in this article uses as its core the matrix version of the Lowry model developed by Garin. The model allocates basic employment to the zones of an urban area in order to minimize work and service trips. A hypothetical planning problem for Metropolitan Toronto illustrates use of the model. 相似文献
20.
基于LandScan全球人口和ESA全球土地利用数据,构建2000—2015年中国省域人口空间结构数据库,刻画省域人口空间结构的时空格局,进而运用面板固定效应法、两阶段最小二乘法和差分GMM法探索空间结构对省域经济绩效的影响及这种影响对不同规模省域的差异,最后从省会城市集聚（不）经济的角度分析其内在机制。结果发现：① 2000—2015年,中国所有省会城市的人口规模都得到了显著增加,省域人口空间结构存在单中心化的演变趋势,且中西部地区省域人口空间结构相对偏单中心化;② 对所有省份尤其是人口规模相对较小的省份而言,人口空间结构单中心化倾向于提高省域经济效率,而对人口规模相对大的省份,人口空间结构单中心化很可能不利于省域经济效率的提高;③ 省会城市自身已经初显集聚不经济的迹象。 相似文献