共查询到20条相似文献，搜索用时 906 毫秒
1.
Misspecifications in interaction model distance decay relations: A spatial structure effect 总被引：1，自引：0，他引：1
M. Tiefelsdorf 《Journal of Geographical Systems》2003,5(1):25-50
An exclusively statistical approach is proposed to address the spatial structure effects of general interaction models. It is shown that the spatial heterogeneity in the estimated region-specific distance decay
parameters may in part be due to the combination of two factors: (a) a functional mis-specification of the global distance
decay relationship; and (b) the heterogeneity in the region-specific conditional distance distributions. A properly specified
global distance decay function allows controlling for these spatially induced biases in the local distance decay parameters.
However, inherent multicollinearities between the set of region specific distance decay parameters and other estimated model
parameters prevent an unambiguous interpretation. A key conclusion is that a proper model specification, in particular, the
specification of the global distance decay relationship, is of paramount importance in interaction modeling and for accessibility
studies.
Received: September 2002 / Accepted: January 2003 相似文献
2.
Modeling network autocorrelation within migration flows by eigenvector spatial filtering 总被引：8，自引：5，他引：3
Yongwan Chun 《Journal of Geographical Systems》2008,10(4):317-344
Although the assumption of independence among interaction flows frequently is engaged in spatial interaction modeling, in
many circumstances it leads to misspecified models and incorrect inferences. An informed approach is to explicitly incorporate
an assumed relationship structure among the interaction flows, and to explicitly model the network autocorrelation. This paper
illustrates such an approach in the context of U.S. interstate migration flows. Behavioral assumptions, similar to those of
the intervening opportunities or the competing destinations concepts, exemplify how to specify network flows that are related
to particular origin–destination combinations. The stepwise incorporation of eigenvectors, which are extracted from a network
link matrix, captures the network autocorrelation in a Poisson regression model specification context. Spatial autocorrelation
in Poisson regression is measured by the test statistic of Jacqmin-Gadda et al. (Stat Med
16(11):1283–1297, 1997). Results show that estimated regression parameters in the spatial filtering interaction model become
more intuitively interpretable.
相似文献
| Yongwan ChunEmail: |
3.
矢量GIS空间方向关系的演算模型 总被引：5，自引：0，他引：5
空间方向关系是描述空间目标间位置分布的一类基本空间约束，在GIS中是由形式化模型描述的。但现有模型由于简化假设过多，其描述分辨率较低。以点／点空间方向关系的计算量为基础，在综合考虑空间目标的几何构成和分布关系后，提出了定量化演算空间方向关系的一种新模型。利用该模型的结果，根据定量表达与定性描述之间的转换函数，可以得到相应的定性描述结果。理论分析和算例表明，新模型对目标间距离和目标本身的形状等影响方向关系的参数更为敏感，因而比现有模型有更高的描述分辨率。 相似文献
4.
Deepak Kumar 《国际地球制图》2013,28(13):1477-1495
AbstractThere is an urgent need for alternate energy resources throughout the world due to the decline in the accessibility of fossil fuels and other conventional resources. In this pursuit, solar energy offers a favourable solution and can easily be converted into energy. There are some solar radiation models which provide point and area-based computations based on the geometry of surface orientation and visible sky. The work comprises the mapping of the solar energy generation potential of southern India to balance the competing and upcoming energy demands. The current work explores and employs the geospatial technology to prepare solar energy potential map to deliver the valuable inputs to the energy sector. The research was supported with satellite-derived global solar radiation and temperature data over a span of one year. The values obtained from the spatial radiation models were processed to get the improved datasets. Suitable cartographic visualization of solar insolation parameters was presented for enhanced understanding of the spatial distribution of solar potential, PV output, air-temperature or other spatial characteristics. Twelve monthly maps, an annual map, and another map with the location of the measurement stations were created to unravel a number of unturned mystery about the understanding of solar resource diversity in a spatial context, which will support our decisions & arguments for any kind business. 相似文献
5.
6.
Daniel A. Griffith 《Journal of Geographical Systems》2002,4(1):43-51
As either the spatial resolution or the spatial scale for a geographic landscape increases, both latent spatial dependence
and spatial heterogeneity also will tend to increase. In addition, the amount of georeferenced data that results becomes massively
large. These features of high spatial resolution hyperspectral data present several impediments to conducting a spatial statistical
analysis of such data. Foremost is the requirement of popular spatial autoregressive models to compute eigenvalues for a row-standardized
geographic weights matrix that depicts the geographic configuration of an image's pixels. A second drawback arises from a
need to account for increased spatial heterogeneity. And a third concern stems from the usefulness of marrying geostatistical
and spatial autoregressive models in order to employ their combined power in a spatial analysis. Research reported in this
paper addresses all three of these topics, proposing successful ways to prevent them from hindering a spatial statistical
analysis. For illustrative purposes, the proposed techniques are employed in a spatial analysis of a high spatial resolution
hyperspectral image collected during research on riparian habitats in the Yellowstone ecosystem.
Received: 25 February 2001 / Accepted: 2 August 2001 相似文献
7.
GIS空间目标的广义Hausdorff距离模型 总被引：4，自引：0，他引：4
分析了GIS中常用的空间距离度量及其存在的问题，这些距离度量没有顾及空间目标的整体形状、位置分布等特征。基于此，引入了Hausdorff距离的概念，给出了Hausdorff距离的计算方法，分析指出了Hausdorff距离容易受空间目标局部几何形状的影响。进而从统计学的角度分析了现有的距离度量并不能有效地表达空间目标间距离的整体分布，并提出了一种广义Hausdorff距离模型，这种距离模型能够度量空间目标间距离分布的中心趋势和离散度。实际算例证明了此模型在GIS环境下的实现方法。 相似文献
8.
Roger Bivand 《Journal of Geographical Systems》2002,4(4):405-421
Placing spatial econometrics and more generally spatial statistics in the context of an extensible data analysis environment
such as R exposes similarities and differences between traditions of analysis. This can be fruitful, and is explored here
in relation to prediction and other methods usually applied to fitted models in R. Objects in R may be assigned a class attribute,
including fitted model objects. Such fitted model objects may be provided with methods allowing them to be displayed, compared,
and used for prediction, and it is of interest to see whether fitted spatial models can be treated in the same way.
Received: 26 August 2002 / Revised version: 15 January 2003 相似文献
9.
Modeling spatial autocorrelation in spatial interaction data: empirical evidence from 2002 Germany journey-to-work flows 总被引：3，自引：3，他引：0
Daniel A. Griffith 《Journal of Geographical Systems》2009,11(2):117-140
Since before the inception of work by Okabe, the intermingling of spatial autocorrelation (i.e., local distance and configuration)
and distance decay (i.e., global distance) effects has been suspected in spatial interaction data. This convolution was first
treated conceptually because technology and methodology did not exist at the time to easily or fully address spatial autocorrelation
effects within spatial interaction model specifications. Today, however, sufficient computer power coupled with eigenfunction-based
spatial filtering offers a means for accommodating spatial autocorrelation effects within a spatial interaction model for
modest-sized problems. In keeping with Okabe’s more recent efforts to dissemination spatial analysis tools, this paper summarizes
how to implement the methodology utilized to analyze a particular empirical flows dataset.
相似文献
| Daniel A. GriffithEmail: |
10.
This paper reports the results of an empirical comparison of various types of competing risk models in predicting the timing
and duration of activities. In particular, three types of models are compared: a non-competing risk model, an unconditional
competing risk model, and a conditional competing risk model. The models are applied to an activity diary, collected in the
Netherlands. The results of the comparison indicate that the conditional competing risk model performs best, indicating that
the choice and timing of activities depends on the nature and duration of the activity conducted previously. The specific
structure of these dependent transition probabilities are discussed in detail. Several socio-demographic variables are found
to be significantly related to the transition probabilities.
Received: 19 July 2001 / Accepted: 25 January 2002 相似文献
11.
R. G. V. Baker 《Journal of Geographical Systems》2005,7(3-4):361-379
The Internet has been publicly portrayed as a new technological horizon yielding instantaneous interaction to a point where
geography no longer matters. This research aims to dispel this impression by applying a dynamic form of trip modelling to
investigate pings in a global computer network compiled by the Stanford Linear Accelerator Centre (SLAC) from 1998 to 2004.
Internet flows have been predicted to have the same mathematical operators as trips to a supermarket, since they are both
periodic and constrained by a distance metric. Both actual and virtual trips are part of a spectrum of origin–destination
pairs in the time–space convergence of trip time-lines. Internet interaction is very near to the convergence of these time-lines
(at a very small time scale in milliseconds, but with interactions over thousands of kilometres). There is a lag effect and
this is formalised by the derivation of Gaussian and gravity inequalities between the time taken (Δt) and the partitioning of distance (Δx). This inequality seems to be robust for a regression of Δt to Δx in the SLAC data set for each year (1998 to 2004). There is a constant ‘forbidden zone’ in the interaction, underpinned by
the fact that pings do not travel faster than the speed of light. Superimposed upon this zone is the network capacity where
a linear regression of Δt to Δx is a proxy summarising global Internet connectivity for that year. The results suggest that there has been a substantial
improvement in connectivity over the period with R
2 increasing steadily from 0.39 to 0.65 from less Gaussian spreading of the ping latencies. Further, the regression line shifts
towards the inequality boundary from 1998 to 2004, where the increased slope shows a greater proportional rise in local connectivity
over global connectivity. A conclusion is that national geography still does matter in spatial interaction modelling of the
Internet. 相似文献
12.
Analysing regional industrialisation in Jiangsu province using geographically weighted regression 总被引：6，自引：0，他引：6
Industry is the most important sector in the Chinese economy. To identify the spatial interaction between the level of regional
industrialisation and various factors, this paper takes Jiangsu province of China as a case study. To unravel the existence
of spatial nonstationarity, geographically weighted regression (GWR) is employed in this article. Conventional regression
analysis can only produce `average' and `global' parameter estimates rather than `local' parameter estimates which vary over
space in some spatial systems. Geographically weighted regression (GWR), on the other hand, is a relatively simple, but useful
new technique for the analysis of spatial nonstationarity. Using the GWR technique to study regional industrialisation in
Jiangsu province, it is found that there is a significant difference between the ordinary linear regression (OLR) and GWR
models. The relationships between the level of regional industrialisation and various factors show considerable spatial variability.
Received: 4 April 2001 / Accepted: 17 November 2001 相似文献
13.
尺度依赖性、空间依赖性和空间非均质性是空间信息的本质特征,如何在空间分析中综合考虑以上特征目前仍缺少有效方法.本文提出的空间信息分层复合分析模型通过“回归的回归”两阶段分析建立包含空间异质性、空间依赖关系与空间尺度效应的空间单元综合回归模型,有助于解决空间分析中数据的多维复杂性涉及的尺度效应、空间依赖性和空间异质性综合... 相似文献
14.
随着经济的快速发展,城市内部空间结构不断优化。识别城市功能区空间分布及其相互作用规律,对于把握城市空间结构以及制定科学合理的规划具有重要意义。采用重尾打断分类法和核密度聚类法对兴趣点（points of interest,POI）进行分析,识别城市功能区,并结合出租车轨迹数据进行时空挖掘,定量分析典型城市功能区交通吸引规律及其相互作用强度和方向。以北京市五环内主城区为例进行分析,可得:①该方法可以识别典型功能区西单、国贸、中关村是以商业为主的混合城市功能区,望京是以居住为主的混合功能区,且居民通勤出行特征明显;②国贸对自身的引力较强（39.4%）,说明国贸区域城市功能更加齐全;③典型功能区对居民出行距离范围内的区域吸引力随着距离的增加而减弱,符合经验认知和地理空间衰减规律。结果表明,利用POI和移动大数据采用重尾打断分类法和核密度聚类法进行城市功能区识别与分析是可行和有效的。 相似文献
15.
In this paper an intervening opportunities model with spatial dominance is developed. The usual assumption in spatial theory
is that decision makers are influenced not just by the size of a destination or distance but by these two factors in combination, that is, spatial dominance. Decision-makers will have more knowledge about, and clearly perceive destinations that exert
the greatest amount of spatial dominance on their origins, just as they would primate cities. Thus destinations are ranked
in terms of the spatial dominance calculated for each destination. Empirical verification of the model utilizes state-to-state
migration flow data for the US. Calibration results compare favourably with the traditional intervening opportunities model
and the production constrained gravity model.
Received: 7 October 1999/Accepted: 15 June 2000 相似文献
16.
公共医疗卫生服务的空间可达性研究——以广州市海珠区为例 总被引：9，自引：0，他引：9
本文以第5次人口普查以及医疗卫生机构相关数据为基础,运用空间相互作用理论和模型,得到广州市海珠区各街区的公共医疗卫生服务可达性空间分布,并详细分析了医院等级系数对可达性指数的影响,为医疗卫生事业的发展规划提供辅助决策支持。 相似文献
17.
针对城市地价定量化研究和空间可视化表达的方法体系已日渐成熟的现状,该文以2008至2014年间,石家庄市主城区土地交易数据作为研究样本,借助ArcGIS、GS+软件平台,分别建立石家庄市城区商业和住宅数字地价模型,并依据模型进行地价数量特征、剖面特征、等值线形态特征分析等一系列空间分析。研究表明:石家庄市城区商业地价分布,整体上呈现出围绕一个传统的一级商业中心和一个新兴的次级商业中心向边缘衰减的圈层结构;住宅地价分布呈现出多峰值、多方向山脊状圈层衰减的结构,且聚集效应不及商业地价明显,衰减趋势较平缓。 相似文献
18.
Anabele Lindner Cira Souza Pitombo Samille Santos Rocha José Alberto Quintanilha 《地球空间信息科学学报》2016,19(4):245-254
Studies in transportation planning routinely use data in which location attributes are an important source of information. Thus, using spatial attributes in urban travel forecasting models seems reasonable. The main objective of this paper is to estimate transit trip production using Factorial Kriging with External Drift (FKED) through an aggregated data case study of Traffic Analysis Zones in São Paulo city, Brazil. The method consists of a sequential application of Principal Components Analysis (PCA) and Kriging with External Drift (KED). The traditional Linear Regression (LR) model was adopted with the aim of validating the proposed method. The results show that PCA summarizes and combines 23 socioeconomic variables using 4 components. The first component is introduced in KED, as secondary information, to estimate transit trip production by public transport in geographic coordinates where there is no prior knowledge of the values. Cross-validation for the FKED model presented high values of the correlation coefficient between estimated and observed values. Moreover, low error values were observed. The accuracy of the LR model was similar to FKED. However, the proposed method is able to map the transit trip production in several geographical coordinates of non-sampled values. 相似文献
19.
Constrained variants of the gravity model and spatial dependence: model specification and estimation issues 总被引：1，自引：1，他引：0
In this paper, we distinguish three constrained variants of the gravity model of spatial interaction: doubly constrained, production constrained and attraction constrained exponential gravity models. These model variants include origin- and/or destination-specific balancing factors that act as constraints to ensure that the estimated rows and columns of the flow data matrix sum to the observed row and column totals. Because flows are typically counts, the Poisson rather than the normal probability model specification furnishes the appropriate statistical distribution, and parameter estimation can be achieved via Poisson regression. This probability model specification motivates the use of origin and/or destination fixed effects or—under certain conditions—the use of origin- and/or destination-specific random effects for model estimation. The paper establishes theoretical connections between balancing factors, fixed effects represented by binary indicator variables and random effects. The results pertaining to both the doubly and singly constrained cases of spatial interaction are illustrated with an empirical example while accounting for spatial dependence between flows from locations neighbouring both the origins and destinations during estimation. 相似文献
20.
基于格式塔识别原则挖掘空间分布模式 总被引：9，自引：2，他引：9
面向空间群目标的分布模式识别是空间数据挖掘比较关注的问题。本研究基于空间认知原理与视觉识别格式塔完形原则并结合空间聚类方法对该问题进行研究,提出用于描述实体间差异的"视觉距离"概念,其定义综合考虑视觉识别中的位置、方向、大小差异,通过Delaunay三角网计算几何构造建立该距离计算的模型。在实验基础上提出基于最小支撑树MST的聚类方法,获得与视觉认知相一致的结果。研究试图表明一个观念,即通用性的数据处理模型在GIS实际应用时,需要根据GIS作为"空间认知"科学的原理,作技术方法上的改进,需要考虑认知主体在感知、辨析、识别、推理不同思维过程中的认知心理原则。 相似文献