“绿道-邻里”视角下建成环境对城市绿道使用的影响——以广州为例

基于“绿道-邻里”视角,采集了广州典型城市绿道上的市民使用人数与类型等属性,并运用多元线性回归模型探讨绿道周边建成环境（人口密度和土地类型混合度）与绿道使用之间的关系。结果表明：绿道周边建成环境作为绿道使用的潜在来源地和目的地,影响着城市绿道使用效果,步行和骑行可达范围内的居住区人口密度和绿道周边土地利用混合度均可作为绿道使用强度的解释因子,两者的增加均会带来绿道使用强度的提高;除此之外,周边居民区收入水平、年龄和时间等变量对城市绿道使用也会造成影响。研究结果可为城市绿道建设提供直接参考。     

1947～2007年上海中心城区居住空间分异变化——基于居住用地类型视角

采用4种分异度测度模型,在街坊尺度和乡镇尺度下,对上海中心城区1947～2007年11个时相的各类居住用地空间分异程度进行计算。发现1949年后各类居住用地分异度呈现不同的波动过程。不同时期居住用地总体分异程度的计算表明,1949年前空间分异严重,计划经济时期有所降低,转型期则又明显上升。不同时期居住用地等级高低与其分异度大小呈现不同的结构特征,1949年前高等级居住用地分异度高、中低等级居住用地分异度较低,形成"一高两低"结构;计划经济时期则是居住用地等级越高,分异度越大的"正相关"结构;90年代后则是最高和最低等级的居住用地分异度高,而中等居住用地分异度最低的"V"型结构。不同时期居住用地空间分异结构特征间的演进,直接原因是新式住宅的建设和旧城的改造,深层次原因则是土地使用制度的变迁和城市空间组织模式的转变。     

High density neighborhoods: Who enjoys them?

To date, research into the subjective aspects of high density has focused mainly on the negative consequences of overcrowding. This study, in contrast, outlines some of the positive aspects of high density in neighborhoods, exploring the physical–spatial environment of two neighborhoods in the city of Haifa, Israel. It was found that while the relatively high residential density was similar in both neighborhoods (40 housing units per acre), this was more positively evaluated in one neighborhood as compared to the other. This can be attributed to some specific environmental and planning features. In particular, where physical planning enabled the potential advantages of high density to be realized, this was positively perceived and evaluated by local residents. Such advantages mainly comprised accessibility to a variety of services, more frequent public transportation, and access to open spaces within walking distance. Particularly advantageous were the increased opportunities for social gathering. At the same time, however, high density did not foster social relationships on the neighborhood level. The study further identified the gender and age groups that benefited most from the high density. Thus, women evaluated high density more positively than men. Young families with children and senior citizens (over 65) were also more likely to benefit, and to evaluate the high density environment more positively than other social groups.     

无人机模糊图像自动检测方法

图像模糊程度是图像评价的一个关键指标参数,它影响着图像的质量和信息。特别对于无人机拍摄的图像,如果利用模糊的图像参与计算,会造成很大的误差甚至出现颠覆性的结果。因此对于图像模糊的检测显得至关重要。传统的图像模糊检测方法大都基于人工检测、且有合格的参考图像参与评价过程,方法耗时、费力,无法用于大量无人机拍摄图像的分析。因此本文基于Sobel边缘检测原理,利用4个方向的Sobel算子,寻找图像中每个Sobel边缘点的模糊邻域,并构建模糊邻域宽度值的计算准则,由此来计算出整幅图像的平均模糊邻域宽度值,并将这个计算结果作为检测模糊的直接依据。同时考虑到无人机拍摄图像的特点,将其按照拍摄时间顺序排列,依次将相邻图像互为参考,通过对比互为参考图像的模糊邻域宽度值的变化情况,将宽度值突变的图像确定为模糊图像。据此对无人机拍摄的所有图像进行模糊检测。最终通过7组2322张 图像进行自动检测发现151张图像模糊,通过人工检测发现158张图像模糊,平均检测率95.57%。该检测方法具有较强的 适用性。     

地理多要素Voronoi图相邻关系下的地图放大裁剪方法

针对以欧氏距离作为放大因子对电子地图进行放大裁剪引起的信息失衡问题,提出了采用地理多要素Voronoi图相邻关系的地图放大裁剪方法,可有效避免以欧氏距离作为地图放大因子的地图信息失衡问题。将电子地图中的地理要素分为点、线、面,对于点要素,构建它的Voronoi图;对于非点要素,即线和面要素,构建它们的近似Voronoi图,当用户对电子地图中感兴趣地理要素目标放大时,只需要提取该目标的多要素Voronoi图相邻要素的近似Voronoi图,并计算它们的最小外包矩形,将最小外包矩形区域用于最终的地图放大裁剪区域,则可较好地顾及用户感兴趣地理要素目标周围的地理要素信息,可提高地图的易读性。采用本文方法对某区域电子地图进行了试验,结果表明,地理多要素Voronoi图相邻关系的地图放大裁剪方法能够较好地顾及目标周边地理要素信息,避免了以欧氏距离为放大因子的地图信息失衡。     

基于邻域扩展量化法的城市边界识别

城市空间分析的基本条件是可靠的测度,而城市的基本测度是规模。客观定义城市边界是有效确定城市规模的技术前提。近年来国内外学者提出几种城市边界识别的方法,其中能够定量反映城市内部实体空间组织关系的多采用矢量图像。但这些矢量数据的获取十分困难,且实时性差。因此,本文借鉴前人的研究成果,基于邻域扩展量化和标度思想,提出一种应用于遥感栅格图像上的城市边界识别方法。该方法的本质是一种空间邻域融合法,通过改变像元邻域的作用范围,可以得到不同的空间集群数目;借助搜索范围与集群数目的标度关系确定一个客观的半径,据此可以利用GIS技术确定城市边界。将该方法应用于北京地区多个年份的遥感图像,发现了像元的有效邻域作用范围。此方法以栅格图像为基础,数据实时性好并且获取容易,计算过程简便,在未来的城市边界研究过程中,可望与现有的方法相互补充。     

Multiethnic Economic Activity Along Three Immigrant Corridors in Paris

Ethnic neighborhoods and ethnic economies do not always involve a single nationality or ethnic group. Quite often several groups operate side by side in the neighborhood and within the establishments themselves. This can give rise to a modification of the ethnic economy concept. We discuss an example of such a multiethnic residential and business district in Paris, the Goutte d’Or, with particular attention to three shopping streets. Although somewhat distinct from one another, each of these streets is multiethnic in regard to the proprietors, employees, and customers, and this multiethnicity extends within the establishments themselves. The primary questions we ask in this article are, first, what the nature of this ethnic economy is and how it fits within the different types of ethnic economy. Beyond this, we demonstrate how the activities taking place here reflect separate circuits of activity at separate spatial scales and what this ethnic business activity suggests for immigrant incorporation in Paris and the nature of cross-ethnic relations. To answer these questions, we rely on observation, interviews with several merchants in defined commercial corridors, and some official statistical and political information gleaned from various government sources. This Parisian neighborhood exemplifies strategies of immigrant incorporation into French society. As such, it provides a possible new model of a multiethnic economy, one that might become a common fixture in increasingly diverse cities in the world.     

复杂洪水预报系统的集成技术研究

以广西南盘江天生桥一级电站施工洪水预报系统为例,讨论了以水情数据库、洪水预报模型、数据库管理系统和模型管理器为基础构建集成化复杂洪水预报系统的若干技术问题,提出了用邻接矩阵来形式化和规范化预报系统水情数据与预报模型之间复杂关系的一般方法.     

融合主成分分析和局部邻域的平面点云去噪

大型水工建筑物和城市地下轨道是国家的重要基础设施，人工变形监测耗时费力，利用激光雷达扫描对其进行自动化的变形监测已成为研究热点。而此类建筑物具有较多的平面结构特征，为了高效去除平面结构扫描点云中的噪声点，本文提出了一种融合主成分分析和局部邻域的噪声剔除方法，首先利用主成分分析剔除全局噪声，然后利用局部邻域对局部小噪声进行剔除，结合实例对该方法进行了验证。应用结果表明，该方法效率高、算法简单可行，具有较高的推广应用价值。     

Neighborhood size and spatial scale in raster-based slope calculations

Raster-based slope estimation is routine in GIS. Like many other terrain attributes, the slope at a location is determined from elevations of surrounding cells. This spatial extent – ‘neighborhood size’ – is often treated as the ‘spatial scale’ of the calculation. In fact, neighborhood size and spatial scale are two connected yet different concepts, but few studies have investigated the relationship between them. The distinction is important because neighborhood size is under user control whereas spatial scale is merely implicit in the computational method. This article attempts to clarify and provide a more precise meaning of the two terms by considering slope operators from the standpoint of the frequency (or wavenumber) domain. This article derives analytical expressions for the amplitude response functions of four popular slope estimators. These are used to characterize the individual methods and also to show that the neighborhood size and spatial scale of a slope calculation are not numerically the same. In fact, because there is no single spatial scale that can be unambiguously associated with a given neighborhood size, neighborhood size cannot be an adequate indicator of spatial scale. Furthermore, this article shows that different indices of ‘scale’ yield different impressions about the action of a slope estimator and its response to changing neighborhood size. Therefore, it is necessary to examine the amplitude response function when investigating the spatial scale. The article also provides guidance for GIS practitioners when selecting a slope estimation method.