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101.
运用大众点评网(南京站)餐饮商户的点评数据,在建立口碑评价指标体系的基础上,计算各商户的口碑综合得分和排名,并对城市餐饮业的空间分布格局进行核密度分析和综合评价。研究发现,南京城区餐饮商户大致分为4个等级,呈现“头小底大”的金字塔形状,口碑较差的商户占据绝大多数,中等口碑的商户较为缺乏,餐饮业发展综合水平较低;餐饮业的空间分布主要呈现出以新街口为服务核心,其他多个次级服务中心共生发展的格局;高等级餐饮服务中心仍旧集中在主城区范围内,发展较为孤立,大致表现为服务质量圈层递减或沿交通线路轴向扩展特征;城市商圈业态也会影响传统和休闲类餐饮商户的空间分布趋势。 相似文献
102.
地图学四面体--数字化时代地图学的诠释 总被引:35,自引:4,他引:31
传统地图学研究3个关系:实地-地图,读者-地图,读者-实地.这个学科的框架可以称为"地图学三角形".对这三种关系的研究随学科和行业的不同而各有侧重.数字地图的出现扩大了传统地图学的视野和服务面.现代地图学需要面对6个关系的探讨.除了上述3个关系外,还要增加数字地图-地图,数字地图-实地,数字地图-读者3个关系.新的学科框架变成了"地图学四面体".从"三角形"到"四面体"反映了信息时代地图学的发展与变革.地图学的存在取决于人类对地图永恒的需求和地图本身的科学价值. 相似文献
103.
阐述了Web数据挖掘的概念和特征,在分析XML技术的基础上,介绍了基于XML的Web数据挖掘模型,并对Web数据挖掘的应用领域和范围,尤其是在电子商务方面的应用进行了探讨。 相似文献
104.
地理要素变化检测已成为国家地理信息"十二五"规划和全国地理国情普查的重要组成部分。网页文本中蕴含海量的地理要素信息,尤其是新闻、政府、社交平台等网站的网页文本更新频繁,可为地理要素变化检测提供现势性的数据源。本文针对网页文本中地理要素变化的语言描述特点,构建了表达地理要素变化的语义知识库,设计了搜索引擎和通用主题相结合的网页爬虫,实现了相关网页文本的高效获取;采用规则模型和条件随机场模型,分别进行网页文本中地理要素变化信息抽取,包括地理要素名称、位置(地名)、时间和属性等。实验结果显示,本文设计的网页爬虫具有较高的相关网页文本获取能力,地理要素变化信息抽取的准确率能够达到70%以上,但是,语义知识库的完备程度对于信息抽取性能具有较大影响。研究成果表明,以网页文本为数据源的地理要素变化信息获取方法,能提供一种快速检测地理要素变化的新途径,与实地调绘和遥感影像检测等方法结合应用具有较好的优势互补性,可作为有力的辅助手段解决地理要素的持续更新和实时更新问题。 相似文献
105.
Kelp holdfasts are highly reticulated structures which host a large diversity of small fauna. These microhabitats have been reported to play a crucial role in the biodiversity associated to kelp forest ecosystems. This study aimed at identifying trophic links and the main food sources sustaining food webs within communities associated with kelp holdfasts, through a stable isotope (δ13C and δ15N) approach. Sampling of the main invertebrates inhabiting Laminaria digitata holdfasts, and of their potential food sources, took place in February and May 2007. Stable isotope results reveal that most of the primary consumers, including filter-feeders and deposit-feeders, rely on the particulate organic matter sedimented within kelp holdfasts. Only three grazers departed from this general pattern. The correspondence between the stable isotope ratios of predators and sediment consumers indicated that this source is at the base of the main pathway through which energy and matter transit in the food web. δ15N ranges found for consumers revealed that the food web associated with kelp holdfasts is composed of 3.5 levels. In spite of the low diversity of food sources at the base of the food web, these microhabitats can therefore be considered micro-scale ecosystems, from a functional perspective. 相似文献
106.
论述了满足地图可视化的基本条件和载负量限制;论述了地图比例尺、地图概括及其相关概念的派生逻辑。阐释了由相似比较派生的地图学概念和地图学概念在科学技术发展中不断增加和丰富的必然逻辑。 相似文献
107.
108.
《Geoforum》2017
The Internet and the representation of space therein are almost omnipresent in society and everyday life. Peer-produced geographic data is gaining a particular importance through increasingly available digital tools and techniques that shape the perception of space in the internet, such as flickr, OpenStreetMap or Wikipedia. However, few studies focused on how space is represented, and by whom it is described. We hypothesize that the alleged opening up of geographic information and the assumed benefits for every individual and society through the occurrence of ‘easy-to-use-mapping-tools’ was premature. To explore these assumptions, a comparative study of the flickr worldmap was undertaken and roughly 6.8 million metadatasets of geocoded photos in France, and roughly 50,000 metadatasets in Afghanistan were downloaded and the metadata was analyzed. Our results indicate that photos geocoded in France show a large diversity of motives, while photos geocoded in Afghanistan are mostly limited to content containing warfare when they are up loaded in English. The content of the photo and therefore the representation of space strongly depend on who uploaded the photo, particularly in Afghanistan. We can show that the representation of space on the internet, for the case of flickr, is strongly dominated by perceptions of Western societies and individuals. We therefore confirm our hypothesis that the supposed opening up of geographic information systems through ‘easy-to-use-mapping-tools’ and their democratization thereof was premature. Moreover, we highlight the importance of understanding who contributes online content to be able to evaluate peer-produced data, its value, and its possible applications to avoid reproducing biases. 相似文献
109.
110.
ZHANG Yu ong ZHAN RenBin FAN JunXuan CHENG JunFeng & LIU Xiao LPS Nanjing Institute of Geology Palaeontology Chinese Academy of Sciences Nanjing China 《中国科学:地球科学(英文版)》2010,(3)
The Ordovician radiation is among the major bioevents in earth history that have drawn great attention from geologists all over the world, and there have been hundreds of publications treating various aspects of this radiation. The study of the event involves a broad spectrum of research fields and concerns many scientific questions. Many opinions and hypotheses have been proposed on the triggering and controlling factors of the radiation. Herein the authors critically review the study of the Ordovician rad... 相似文献