城市断裂点理论的验证、扩展及应用

P. D. Converse提出的城市断裂点理论被广泛用来确定城市的空间影响范围和城市经济区的划分。由于该理论仅给出了每两个城市间一个断裂点的计算公式,在实际应用中就出现了多种空间分割方法。分析表明,许多方法是不可行、不严密的。本文通过对比分析Voronoi图和城市断裂点理论的性质,提出了扩展断裂点理论和断裂弧的概念。并证明:在匀质平面区域内,如果两个城市点的权重相同,那么其吸引范围的分界线是这两个城市点连线的垂直平分线;如果它们的权重不同,那么其吸引范围的分界线是一个圆弧;平面内所有断裂点的轨迹分别构成常规Voronoi图和加权Voronoi图,并且每个城市点的权重分别等于其中心性强度值的平方根。最后,以河南省为例进行了城市空间影响范围和城市经济区划分的应用分析。     

Designs for Detecting Spatial Dependence

The aim of this article is to find optimal or nearly optimal designs for experiments to detect spatial dependence that might be in the data. The questions to be answered are: how to optimally select predictor values to detect the spatial structure (if it is existent) and how to avoid to spuriously detect spatial dependence if there is no such structure. The starting point of this analysis involves two different linear regression models: (1) an ordinary linear regression model with i.i.d. error terms—the nonspatial case and (2) a regression model with a spatially autocorrelated error term, a so-called simultaneous spatial autoregressive error model. The procedure can be divided into two main parts: The first is use of an exchange algorithm to find the optimal design for the respective data collection process; for its evaluation an artificial data set was generated and used. The second is estimation of the parameters of the regression model and calculation of Moran's I , which is used as an indicator for spatial dependence in the data set. The method is illustrated by applying it to a well-known case study in spatial analysis.     

The Zone Definition Problem in Location-Allocation Modeling

Location-allocation modeling is a frequently used set of techniques for solving a variety of locational problems, some of which can be politically sensitive. The typical application of a location-allocation model involves locating facilities by selecting a set of sites from a larger set of candidate sites, with the selection procedure being a function of “optimality” in terms of the allocation of demand to the selected sites. In this paper we examine the sensitivity of one particular type of location-allocation model, the p-median procedure, to the definition of spatial units for which demand is measured. We show that a p-median solution is optimal only for a particular definition of spatial units and that variations in the definition of spatial units can cause large deviations in optimal facility locations. The broad implication of these findings is that the outcome of any location-allocation procedure using aggregate data should not be relied upon for planning purposes. This has important implications for a large variety of applications.     

REAL-TIME RISK ANALYSIS FOR HYBRID EARTHQUAKE EARLY WARNING SYSTEMS

Earthquake Early Warning Systems (EEWS), based on real-time prediction of ground motion or structural response measures, may play a role in reducing vulnerability and/or exposition of buildings and lifelines. In fact, recently seismologists developed efficient methods for rapid estimation of event features by means of limited information of the P-waves. Then, when an event is occurring, probabilistic distributions of magnitude and source-to-site distance are available and the prediction of the ground motion at the site, conditioned to the seismic network measures, may be performed in analogy with the Probabilistic Seismic Hazard Analysis (PSHA). Consequently the structural performance may be obtained by the Probabilistic Seismic Demand Analysis (PSDA), and used for real-time risk management purposes. However, such prediction is performed in very uncertain conditions which have to be taken into proper account to limit false and missed alarms. In the present study, real-time risk analysis for early warning purposes is discussed. The magnitude estimation is performed via the Bayesian approach, while the earthquake localization is based on the Voronoi cells. To test the procedure it was applied, by simulation, to the EEWS under development in the Campanian region (southern Italy). The results lead to the conclusion that the PSHA, conditioned to the EEWS, correctly predicts the hazard at the site and that the false/missed alarm probabilities may be controlled by set up of an appropriate decisional rule and alarm threshold.     

Growth of the Lichen Buellia albula and its Potential for Lichenometric Dating in South‐eastern Australia

Lichenometric dating is a cheap, relatively rapid means of dating rock surfaces, which has generally been overlooked in Australia. While lichenometry finds its greatest application in arctic and alpine geomorphological studies, there has been limited application to archaeological studies. This project set out to test the technique in south‐eastern Australia, and assess its usefulness for dating post‐settlement artefacts. The diameters of Buellia albula lichens growing on well‐dated memorials in the Bendigo cemetery were measured, and the relationship between age and lichen diameter established. The results indicate that B. albula can be used to determine the age of exposed cement surfaces from the 1890s to the present. The positive results suggest the technique should be investigated in other applications and environments in Australia, particularly where alternative dating techniques cannot be used.     

Privacy and False Identification Risk in Geomasking Techniques

Recent years have seen an increase in location privacy research, including the application of geomasking procedures. Geographical masks aim to protect privacy and preserve spatial information through the displacement of point data. False identification, or the mistaken association of data with the incorrect person or household, is an unexplored issue in geomasking, despite legal protections against false association. This study introduces a topological framework for assessing identification risk and examines the risk of false identification in four masking techniques: random perturbation, donut masking, and the newer Voronoi and MGRS masking techniques. While Voronoi masking is found to best preserve the clustering properties of a sample of urban foreclosure data, the other three masking techniques result in better protection against correct and false identification.     

The Fractal Theory of Central Place Geometry: A Diophantine Analysis of Fractal Generators for Arbitrary Löschian Numbers

We develop material to determine whether or not an arbitrary number is Löschian; the procedure embodied in the theorems achieves the desired result more swiftly than do previous solutions to this problem. The correspondence between a partition of the central place lattice and a quadratic form permits the rapid determination of the lattice coordinates of an arbitrary Löschian number and of the exact shape of a single fractal generator used to form an entire central place hierarchy associated with an arbitrary Löschian number. Central place hierarchies may be generated geometrically using a single shape applied initially to a hexagon and subsequently, scaled appropriately, to resultant polygons. Fractional dimensions of arbitrary central place hierarchies, measuring their “space-filling” characteristics, follow naturally from this general procedure.     

Shortest Distances in a Modified Transportation Network

Taking as the starting point an undirected source network and a set of possible new links that can be used to extend the source network, a method is proposed to determine, by simple inspection of a matrix tableau, all shortest distances in any extended network, without using a shortest path algorithm. In consequence, this method may be a useful tool for analyzing and judging network extensions. In particular, computation time can be saved in many complex network optimization methods that use shortest path algorithms. The computer experiments show that the method is feasible even when an extended network may differ from the source network by several dozens of branches.     

Application of LASSO to the Eigenvector Selection Problem in Eigenvector‐based Spatial Filtering

Eigenvector‐based spatial filtering is one of the often used approaches to model spatial autocorrelation among the observations or errors in a regression model. In this approach, a subset of eigenvectors extracted from a modified spatial weight matrix is added to the model as explanatory variables. The subset is typically specified via the selection procedure of the forward stepwise model, but it is disappointingly slow when the observations n take a large number. Hence, as a complement or alternative, the present article proposes the use of the least absolute shrinkage and selection operator (LASSO) to select the eigenvectors. The LASSO model selection procedure was applied to the well‐known Boston housing data set and simulation data set, and its performance was compared with the stepwise procedure. The obtained results suggest that the LASSO procedure is fairly fast compared with the stepwise procedure, and can select eigenvectors effectively even if the data set is relatively large (n = 10⁴), to which the forward stepwise procedure is not easy to apply.     

MODELLING OF THE GROUND MOTION AT RUSSE SITE (NE BULGARIA) DUE TO THE VRANCEA EARTHQUAKES

An approach, capable of synthesising strong ground motion from a basic understanding of fault mechanism and of seismic wave propagation in the Earth, is applied to model the seismic input at a set of 25 sites along a chosen profile at Russe, NE Bulgaria, due to two intermediate-depth Vrancea events (August 30, 1986, M _ω=7.2, and May 30, 1990, M _ω=6.9). Accordingly to our results, once a strong ground motion parameter has been selected to characterise the ground motion, it is necessary to investigate the relationships between its values and the features of the earthquake source, the path to the site and the nature of the site. Therefore, a proper seismic hazard assessment requires an appro-priate parametric study to define the different ground shaking scenarios corresponding to the relevant seismogenic zones affecting the given site. Site response assessment is provided simultaneously in frequency and space domains, and thus the applied procedure differs from the traditional engineering approach that discusses the site as a single point. The applied procedure can be efficiently used to estimate the ground motion for different purposes like microzonation, urban planning, retrofitting or insurance of the built environment.     

POPULATION DENSITY IN A CENTRAL‐PLACE SYSTEM

The existing empirical literature about polycentric population density has focused on the urban scale, and the alternative models proposed in that context have been justified using heuristic arguments. This paper describes how polycentric density distributions can, in general, be endowed with a theoretical framework which differs from the existing literature with respect to the treatment of centers: instead of assuming that they represent places of work, it assumes they are places that provide goods and services to households. This imposes a hierarchical structure on the model, which allows replacing the set of distances to all centers (typically used in the existing literature as the same explanans irrespectively of location) with a smaller set of distances that corresponds to the number of levels in the hierarchy and varies with location. The central‐place framework used also provides a direct link between a polycentric model and the Clark formula, in the sense that the latter can emerge through a smoothing procedure of the former. Finally, in the context of central places, the scope of related empirical investigations can be extended naturally from the urban to the regional scale. This is the scale of a simple test presented here, which has been specifically included to support the corresponding theoretical arguments about the structure of a polycentric density gradient. The paper concludes with some expected problems and advantages of applying these ideas to the urban scale.     

Examining Land-Use through GIS-Based Kernel Density Estimation: A Re-Evaluation of Legacy Data from the Berbati-Limnes Survey

The use of archaeological survey data for evaluation of landscape dynamics has commonly been concerned with the distribution of settlements and changes in number of recorded sites over time. Here we present a new quantitative approach to survey-based legacy data, which allows further assessments of the spatial configuration of possible land-use areas. Utilizing data from an intensive archaeological survey in the Berbati-Limnes area, Greece, we demonstrate how GIS-based kernel density estimations (KDE) can be used to produce cluster-based density surfaces that may be linked to past land-use strategies. By relating density surfaces to elevation and slope, it is also possible to quantify shifts in the use of specific environments on a regional scale, allowing us to model and visualize land-use dynamics over time. In this respect, the approach provides more multifaceted information to be drawn from archaeological legacy data, providing an extended platform for research on human-environment interactions.     

Reconstructing Population Density Surfaces from Areal Data: A Comparison of Tobler's Pycnophylactic Interpolation Method and Area-to-Point Kriging

We compare Tobler's pycnophylactic interpolation method with the geostatistical approach of area-to-point kriging for distributing population data collected by areal unit in 18 census tracts in Ann Arbor for 1970 to reconstruct a population density surface. In both methods, (1) the areal data are reproduced when the predicted population density is upscaled; (2) physical boundary conditions are accounted for, if they exist; and (3) inequality constraints, such as the requirement of non-negative point predictions, are satisfied. The results show that when a certain variogram model, that is, the de Wijsian model corresponding to the free-space Green's function of Laplace's equation, is used in the geostatistical approach under the same boundary condition and constraints with Tobler's approach, the predicted population density surfaces are almost identical (up to numerical errors and discretization discrepancies). The implications of these findings are twofold: (1) multiple attribute surfaces can be constructed from areal data using the geostatistical approach, depending on the particular point variogram model adopted—that variogram model need not be the one associated with Tobler's solution and (2) it is the analyst's responsibility to justify whether the smoothness criterion employed in Tobler's approach is relevant to the particular application at hand. A notable advantage of the geostatistical approach over Tobler's is that it allows reporting the uncertainty or reliability of the interpolated values, with critical implications for uncertainty propagation in spatial analysis operations.     

互联网信息对健身俱乐部连锁店空间竞争的指示研究

以北京浩沙健身连锁俱乐部为例,尝试利用公众在大众点评网、新浪微博等网络社区中发布的关注度、评价等作为加权因子,分析连锁网点之间的竞争状态,建立了一个基于互联网信息的加权因子计算模型,计算各连锁店的市场竞争域,结果显示互联网空间信息能够对连锁店之间的空间竞争产生指示作用,各分店表现出明显的竞争力差异;提出对加权Voronoi图区位意义上的地理学新解释:它不仅反映连锁店基本市场域,而且其边线弯曲度和单元面积的变化还可折射各连锁店在互联网空间中的吸引力差异。     

A Modified Capacity Spectrum Method with Direct Calculation of Seismic Intensity of Points on Capacity Curve

A direct methodology for solving the seismic intensity of each point on the capacity curve is proposed. By utilizing the procedure, a continuous curve between the structural response and the seismic intensity, the structural response function, can be easily generated. Unlike previous procedures that search for the performance point of a determined seismic intensity, the proposed methodology easily draws the full curve without iterations. The procedure is applicable to both a smooth design spectrum and an actual response spectrum. Examples indicate the methodology is accurate and fast, and convenient to be combined with existing procedures, such as Modal Pushover Analysis.     

The ILO: An Agency for Globalization?

The International Labour Organization, set up in 1919 to develop and promote labour standards, is at a crucial point. It has preached that labour is not a commodity and in 1969 received the Nobel Peace Prize. Since then it has run into trouble. This article considers how the ILO has failed to come to terms with the Global Transformation, seeing it as trying to play three roles — a standard‐setter, a technical assistance agency and a knowledge generator — without developing the professional capacity to do so. The big question is whether the ILO could become an effective development agency given the changing character of work and labour in globalizing labour markets and its antiquated governance structure.     

ON THE SENSITIVITY OF GRAVITY MODEL FORECASTS*

In this paper we present a procedure for estimating small changes in gravity model forecasts in response to small changes in input values (trip end totals and/or parameter values). The procedure can be used to derive covariance matrices from which confidence intervals may be obtained and which may be used for tests of hypotheses. While this type of problem has been addressed by others, our approach is the only one that is conveniently applicable to the doubly constrained model and can accommodate the large numbers of origin and destination zones one typically encounters.     

SANET: A Toolbox for Spatial Analysis on a Network

This article shows a geographical information systems (GIS)-based toolbox for analyzing spatial phenomena that occur on a network (e.g., traffic accidents) or almost along a network (e.g., fast-food stores in a downtown). The toolbox contains 13 tools: random point generation on a network, the Voronoi diagram, the K -function and cross K -function methods, the unconditional and conditional nearest-neighbor distance methods, the Hull model, and preprocessing tools. The article also shows a few actual analyses carried out with these tools.     

基于离散程度的博物馆馆藏环境温湿度中长期评估方法

温湿度是评估博物馆馆藏环境的重要指标。在越来越多的博物馆对温湿度进行监测记录的情况下,需要基于"稳定适宜"的准则,探索一种科学的评估方法,为馆藏环境温湿度的调控治理提供依据。该方法以中长期的博物馆监控数据为基础,通过计算温湿度监控数据的离散度和离散系数,并结合箱线图分析数据的分布情况,对其"稳定适宜"程度进行综合量化评估。结合四川博物院2014年的温湿度监控数据的实例,验证了该方法的有效性。研究结果表明,采用基于离散程度的中长期温湿度数据评估方法,能够为下一步的馆藏环境调控治理提供依据,有助于针对性的改善博物馆文物保存环境。