地理信息系统与空间数据库研究

本文分析了地理信息系统的基本发展情况，对空间数据库的特点．分类详细的进行了描述。以某土地资源空间数据库的建立为例，展示了空间数据库的应用情况。     

On The Application of Fuzzy Clustering for Crime Hot Spot Detection

   One of the fundamental challenges in crime mapping and analysis is pattern recognition. Efforts and methods to detect crime hot-spots, or geographic areas of elevated criminal activity, are wide ranging. For aggregate data, such as total crime events in a census tract(s), measures of spatial autocorrelation have proven useful. For disaggregate data (i.e. individual crime events), kernel density smoothing and non-hierarchical cluster analysis (e.g. k-means), are widely used. Non-hierarchical techniques are particularly effective in delineating geographic space into areas of higher or lower crime concentrations, because each observation is assigned to one and only one cluster. The resulting set of partitions provides clear-cut spatial boundaries that can be used for hot-spot evaluation and interpretation. However, the strength of non-hierarchical methods can also be viewed as a weakness. Although the hard-clustering of observations into a set of discrete clusters is helpful, there are many cases where ambiguity exists in the data. In such cases, a more generalized approach for hot-spot detection would be helpful. The purpose of this paper is to explore the use of a generalized partitioning method known as fuzzy clustering for hot-spot detection. Functional and visual comparisons of fuzzy clustering and two hard-clustering approaches (medoid and k-means), across a range of cluster values are analyzed. The empirical results suggest that a fuzzy clustering approach is better equipped to handle intermediate cases and spatial outliers.

Does local access to employment services reduce unemployment? A GIS analysis of One-Stop Career Centers

The paper uses Geographic Information System to investigate (1) the location of One-Stop Career Centers in Southern California, (2) their level of accessibility to unemployed workers of various demographic groups, (3) their proximity to employment opportunities, and (4) the effect of these spatial relations on Census tract unemployment. We build on the non-profit literature on accessibility to social service providers and on spatial mismatch research that emphasizes the gap between places of work and residence. We argue that One-Stops can play an important role in bridging this gap. We find that One-Stops are well positioned to serve the unemployed, although accessibility varies by race/ethnicity, age, and location. Access to One-Stops reduces local unemployment, particularly in neighborhoods with limited employment opportunities. This effect is larger for groups who experience limited mobility due to gender or race, such as black and female job seekers.

城市应急指挥基于GIS的智能辅助决策探究

ＧＩＳ智能辅助决策是未来城市应急指挥的重要手段。本文对ＧＩＳ智能辅助决策的特点、与之有关的主要要素以及为实现这一目标需要采取的措施进行了阐述，并给出了在技术上实现ＧＩＳ智能辅助决策的要点。     

Do crime hot spots affect housing prices?

ABSTRACT

Our knowledge about what happens to housing values when properties are close to places with high concentrations of crime, often called ‘hot spots’, is limited. Previous research suggests that crime depresses property prices overall, but crime hot spots affect house prices more than crime occurrence does and may affect prices of single-family houses more than prices of flats. Here we employ hedonic price modelling to estimate the impact of crime hot spots on housing sales, controlling for property, neighbourhood and city characteristics in the Stockholm metropolitan region, Sweden. Using a Geographic Information System (GIS), we combine property sales by coordinates into a single database with locations of crime hot spots. The overall effect on house prices of crime (measured as crime rates) is relatively small, but if its impact is measured by distance to a crime hot spot, the effect is non-negligible. By moving a house 1 km further away from a crime hot spot, its value increases by more than SEK 30,000 (about EUR 2,797). Vandalism is the type of crime that most affects prices for both multi- and single-family housing, but that effect decreases with distance from a crime hot spot.     

Resident-Defined Neighborhood Mapping: Using GIS to Analyze Phenomenological Neighborhoods

Using a natural quasi-experimental pretest/posttest design, residents in randomly selected homes in a suburb of Los Angeles were surveyed about their perceptions of their neighborhoods with respect to cohesion and sense of community. Responses from the pretest surveys—administered before the construction of a freeway that would bisect the city—were compared to the responses from the posttest survey six years later, administered two years after completion of the freeway. Respondents living adjacent to the new freeway—residents who experienced a fourfold increase in the average decibel levels in their neighborhoods since the freeway opened—reported both a lower sense of community and smaller neighborhood areas as compared to residents not living adjacent to the freeway and as compared to the results from the pretest. The analysis of the data incorporated geographic information system (GIS) software to allow for the analysis of phenomenological neighborhoods—neighborhoods as defined by respondents. This Resident-defined Neighborhood Mapping methodology permitted us to analyze neighborhoods as the respondents outlined them, not as they were preconceived by someone outside the neighborhood. It is suggested that this new methodology may prove useful in advancing the field of neighborhood research by detecting neighborhood-level change that traditional methods may miss.     

Measuring the Geographical Displacement and Diffusion of Benefit Effects of Crime Prevention Activity

The displacement of crime is an important criminological phenomenon. However, while there has been theoretical discussion of this issue in the research literature, there has been little in the way of either standardized empirical work that investigates the incidence of displacement or in the development of techniques that can be used to measure it. In the current paper we discuss a new technique, the weighted displacement quotient (WDQ), that was developed to measure the geographical displacement of crime. A critical feature of the rationale is that displacement can only be attributed to crime prevention activity if crime is reduced in the target area considered. Thus, the WDQ not only measures what occurs in a buffer (displacement) zone but also relates changes in this area to those in the target area. Part of the appeal of the measure is that it can be used either with aggregate or disaggregate crime data and for any geographical boundary selected, provided the appropriate data are available. In addition to detecting displacement, when detailed data are available, the technique can also be used to identify where the effect was most prominent. The WDQ can equally be used to measure the diffusion of benefit of any crime prevention activity. A series of examples are presented for illustration purposes.     

基于GIS的城市品牌信息管理系统的设计

城市品牌塑造关系城市的发展,传统城市品牌塑造中存在一些问题,研究设计基于GIS的城市品牌信息管理系统,该系统选取VB6.0开发平台,使用MapX、AE或者MO等地图控件,可以多形式显示数据,有利于资料的有序化管理,更好地反映数据的空间信息,大大提高信息管理效率。     

Saturation Foot-Patrol in a High-Violence Area: A Quasi-Experimental Evaluation

Shoplifting is one of the most common and costly crimes, yet little data exist to determine reliably characteristics of the typical shoplifter or the modus operandi of the crime. It is a crime that has most often been studied using official, secondary data provided by either retail security personnel or law enforcement officers. Reliability issues plague these official data. Continuing the “dark figure of crime” tradition, this study examines shoplifting by covert observation with a camera system installed in a typical suburban retail drug store. A standardized data template was used to record the demographic and behavioral characteristics of shoppers. Significant numbers of shoppers (8.5%) were observed shoplifting. Logistic regression analysis reveals that, while members of some demographic groups shoplifted more often than others, behavioral indicators carried far more predictive power. The methodology and findings are considered within the larger context of the law enforcement and “profiling” literatures.