空白区域对点群相似性特征因子的影响

针对空白区域对点群相似性特征因子的影响,该文首先综述相关研究文献并整合影响点群相似性的要素,包括拓扑关系、方向关系、距离关系和分布范围;然后通过自适应聚类方法提取点群目标中的空白区域。通过对考虑空白区域与未考虑空白区域点群目标之间的拓扑关系、方向关系、距离关系和分布范围的相似度计算并进行对比,发现点群中的空白区域对点群的拓扑关系之间的相似度计算影响较小,对点群的方向关系、距离关系和分布范围的相似度计算影响较大。     

基于GIS的山东省中心城市发展水平综合评价

城市在区域发展中占有主导地位,中心城市的综合发展是带动周边地区发展的重要动力,通过城市的优先发展来带动周围区域的发展是国际经验。本文运用主成分分析法和聚类分析的方法,对山东省17个中心城市发展水平做了综合评价,主要成果是:首先,建立中心城市发展水平指标体系,共4个影响因素,20个评价指标;其次,用主成分分析法得出17个中心城市相应的得分并排出名次;最后,用聚类分析的方法将17个城市分成4类。     

Construction of design hyetographs for locations without observed data

A design hyetograph which represents the time distribution of design rainfall depth corresponding to a duration and a return period is essential in hydrologic design. However, for locations without observed data (ungauged sites), construction of design hyetographs is a difficult task because of the lack of data. Hence, an approach based on self‐organizing map (SOM) is proposed in this paper to construct design hyetographs at ungauged sites. SOM, which is a special kind of artificial neural networks (ANNs), is a powerful technique for extracting and visualizing salient features of data and for solving classification problems. The proposed approach is composed of three steps: classification, assignment and construction. First, the SOM‐based classification is performed to analyse gauged sites' design hyetographs. Second, based on the concept of indicator kriging, a method is developed to assign an ungauged site of interest to a certain cluster. Third, based on the spatial information, the clustering results, and the design hyetographs of gauged sites, the design hyetograph at the site of interest is constructed using the reciprocal‐distance‐squared method. An application is conducted to assess the advantages of the proposed approach over the conventional approaches. Moreover, cross‐validation tests are applied to evaluate the performance of the accuracy and the robustness of the proposed approach. The results confirm the improvement in performance by using the proposed approach instead of conventional approaches. The proposed approach is useful for constructing design hyetographs at ungauged sites. Copyright © 2009 John Wiley & Sons, Ltd.     

区域制造业集群的辨识——以北京市制造业为例

辨识产业集群的定性方法,过于依赖专家的主观判断,存在诸多局限性。基于投入产出表构建一个反映产业之间功能联系的矩阵,采用主成分分析定量辨识基于经济技术联系的区域产业集群。此外,设计了几个衡量集群内产业联系强度的系数来判定被辨识集群的合理性,并通过相关系数衡量集群内产业的空间集聚特性。以北京市1997年投入产出表上74个制造业行业为例,采用主成分分析方法辨别出14个产业集群,包括钢压延加工集群、有机化学制品集群、电子元器件集群以及棉毛纺织集群等。集群内产业功能联系紧密,相关产业内的企业在空间上集聚,符合产业集群的理论定义。     

旅游者类型及其体验质量研究——以周庄为例

旅游地的客源市场是由不同人口和社会特征的旅游者组成的,他们的旅游动机和需要各不相同,旅游体验质量也存在差异。利用第一手调查资料,在对周庄旅游者动机和体验质量进行调查的基础上,通过因子分析、交互分析和分层聚类的方法,分析了周庄旅游者的旅游动机,根据主导动机的不同将周庄旅游者分为4 种类型,分析了不同类型旅游者的人口社会属性及旅游行为。最后根据不同类型旅游者的需求提出了周庄旅游产品调整的对策。结果表明:身心放松因子是周庄旅游者的基本动机;不同类型旅游者的体验质量存在明显差异,主要受心理内在推力驱使的旅游者的旅游体验质量较高,而主要受旅游地属性外在拉力吸引的旅游者的旅游体验质量较低;不同类型旅游者对周庄自然景观和文化景观的期望值一致很高,而对于周庄的旅游设施、服务、主客关系、产品价格的要求不一。     

广东省地方性城市职能分类

采用2000年广东省人口普查的数据资料,运用多变量聚类和统计分析相结合的方法,对广东省50个地方性城市进行了统一的综合职能分类,共分出职能特征较为明晰的7个大类和反映内部次一级差异的12个亚类,进而揭示各职能类型城市在空间分布上的差异.     

中小企业集群信息技术应用及其影响因素分析 ———以温岭市鞋业集群为例

近年来, 信息技术的广泛应用正在对产业集群的形成和发展产生着深刻的影响。基于现 代信息技术所形成的网络联系逐渐成为产业集群关系网络的主要内容之一, 是深刻理解产业集 群演化和升级机制的重要方面。特别是, 信息技术可以使产业集群内中小企业空间联系的范围扩 大、时间成本下降, 为其走向全球市场提供便利的条件。本文首先回顾了我国企业信息技术应用 的发展过程与具体形式, 并在此基础上阐述了影响中小企业集群中信息技术应用的主要因素, 最 后以浙江省温岭市鞋业集群为案例分析了这些因素的具体作用。     

Multiple criteria rainfall–runoff model calibration using a parallel genetic algorithm in a cluster of computers / Calage multi-critères en modélisation pluie–débit par un algorithme génétique parallèle mis en œuvre par une grappe d'ordinateurs

Abstract

Genetic algorithms are among of the global optimization schemes that have gained popularity as a means to calibrate rainfall–runoff models. However, a conceptual rainfall–runoff model usually includes 10 or more parameters and these are interdependent, which makes the optimization procedure very time-consuming. This may result in the premature termination of the optimization process which will prejudice the quality of the results. Therefore, the speed of optimization procedure is crucial in order to improve the calibration quality and efficiency. A hybrid method that combines a parallel genetic algorithm with a fuzzy optimal model in a cluster of computers is proposed. The method uses the fuzzy optimal model to evaluate multiple alternatives with multiple criteria where chromosomes are the alternatives, whilst the criteria are flood performance measures. In order to easily distinguish the performance of different alternatives and to address the problem of non-uniqueness of optimum, two fuzzy ratios are defined. The new approach has been tested and compared with results obtained by using a two-stage calibration procedure. The current single procedure produces similar results, but is simpler and automatic. Comparison of results between the serial and parallel genetic algorithms showed that the current methodology can significantly reduce the overall optimization time and simultaneously improve the solution quality.     

Regionalization approaches for the periodic parameters of monthly flows: a case study of Ceyhan and Seyhan River basins

Five alternative regionalization approaches in two broad categories, named function‐free and functional approaches, have been proposed to predict periodic behaviours in the basic parameters of monthly stream flows throughout homogeneous regions defined. Function‐free and functional approaches rely on the standardized (or normalized) forms of raw and fitted values of the monthly periodic parameters considered. Homogeneous regions are identified based on these standardized/normalized parameters by means of the hierarchical clustering analysis. The proposed models are tested for two major river basins in south Turkey. It is concluded that the proposed regional models are very effective to estimate periodic behaviour of monthly flows. The functional approaches are quite plausible, and the function‐free approach needs much more parameters. Both types of regionalization approaches can be reliably used to get regional monthly flow estimates for the flow sections where monthly records are not available or too short. Copyright © 2010 John Wiley & Sons, Ltd.