共查询到20条相似文献,搜索用时 31 毫秒
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Paul Longley 《International journal of geographical information science》2013,27(7):1213-1214
With the rising oil prices, climate change, and the ever increasing burden of nutrition-related disease, food security is of growing research interest in academic disciplines spanning agronomy to epidemiology to urban planning. Some governments have developed progressive policies encouraging individuals to consume locally produced foods in order to support local economies, improve agricultural sustainability and community access to food, and to plan and prepare for adverse environmental impacts on food security. However, fundamental methods are lacking for conducting research on food security across these various disciplines. In this article, we first present a method to measure agricultural self-sufficiency, which we refer to as our self-sufficiency index (SSI) for the province of British Columbia, Canada. We then present a Bayesian autoregressive framework utilizing readily available agricultural data to develop predictive smoothing models for the SSI. We find that regional capital investment in agriculture and cropland acreage is the strong predictor of SSI. To accommodate spatial variability, we compare linear regression models with spatially correlated errors to less traditional spatially varying coefficient models, and find that the former class results in better model fit. The smoothed maps suggest that relatively strong self-sufficiency exists only in subset clusters in the Okanagan, Peace River, and lower mainland regions. In spite of policy to promote local food, the existing local agricultural system is insufficient to support a large-scale shift to local diets. Our approach to estimating neighborhood-based self-sufficiency with a predictive model can be extended for use in other regions where limited data are available to directly assess local agriculture and benefit from explicit consideration of spatial structure in the local food system. 相似文献
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基于空间数据挖掘的含义,分析空间数据挖掘的特点、主要方法分类和面临的主要问题;结合空间数据的特点,提出一种空间数据挖掘体系结构,并分析空间数据挖掘的基本过程,阐述了当前空间数据挖掘面临的主要问题并展望其发展趋势。 相似文献
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R. G. HEALEY 《International journal of geographical information science》2013,27(1):141-142
Cartographic modelling operations provide powerful tools for analysing and manipulating geographic data in the raster data model. This research extends these operations to the vector data model. It first discusses how the spatial scopes of analysis can be defined for point, line, and polygon features analogous to the raster cell. Then it introduces the local, focal, and zonal operations available for vector features, followed by providing a prototype syntax that might guide the implementation of these operations. Through example applications, this research also demonstrates the usefulness of these operations by comparing them with traditional vector spatial analysis. 相似文献
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三维地学建模多需海量数据支持,其数据库存储通常采用Oracle的LOB字段,而目前多数Oracle数据库访问接口无法处理大于4 G的LOB字段数据。该文基于面向对象思想,设计并实现了以OCI(Oracle Call Interface)技术为基础的Oracle数据引擎组件,将数据引擎操作的对象划分成多个层次,不仅能处理非海量的常见类型字段的数据,而且支持对4 G以上LOB字段数据的操作。该组件不仅突破了其他技术对Oracle LOB字段访问的限制,而且克服了直接使用OCI接口过于复杂、不利于复用等缺点,具有效率高、资源占用率低等优点。 相似文献
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Coupling mobile phone and social media data: a new approach to understanding urban functions and diurnal patterns 总被引:1,自引:0,他引:1
Wei Tu Jinzhou Cao Shih-Lung Shaw Meng Zhou Zhensheng Wang 《International journal of geographical information science》2017,31(12):2331-2358
Understanding urban functions and their relationships with human activities has great implications for smart and sustainable urban development. In this study, we present a novel approach to uncovering urban functions by aggregating human activities inferred from mobile phone positioning and social media data. First, the homes and workplaces (of travelers) are estimated from mobile phone positioning data to annotate the activities conducted at these locations. The remaining activities (such as shopping, schooling, transportation, recreation and entertainment) are labeled using a hidden Markov model with social knowledge learned from social media check-in data over a lengthy period. By aggregating identified human activities, hourly urban functions are inferred, and the diurnal dynamics of those functions are revealed. An empirical analysis was conducted for the case of Shenzhen, China. The results indicate that the proposed approach can capture citywide dynamics of both human activities and urban functions. It also suggests that although many urban areas have been officially labeled with a single land-use type, they may provide different functions over time depending on the types and range of human activities. The study demonstrates that combining different data on human activities could yield an improved understanding of urban functions, which would benefit short-term urban decision-making and long-term urban policy making. 相似文献
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Socioeconomic segregation in European capital cities. Increasing separation between poor and rich 总被引:1,自引:1,他引:0
Socioeconomic inequality is on the rise in major European cities, as are concerns over it, since it is seen as a threat to social cohesion and stability. Surprisingly, relatively little is known about the spatial dimensions of rising socioeconomic inequality. This paper builds on a study of socioeconomic segregation in 12 European cities: Amsterdam, Athens, Budapest, London, Madrid, Oslo, Prague, Riga, Stockholm, Tallinn, Vienna, and Vilnius. Data used derive from national censuses and registers for 2001 and 2011. The main conclusion is that socioeconomic segregation has increased. This paper develops a rigorous multifactor approach to understand segregation and links it to four underlying, partially overlapping, structural factors: social inequalities, globalization and economic restructuring, welfare regimes, and housing systems. Taking into account contextual factors resulted in a better understanding of actual segregation levels, while introducing time lags between structural factors and segregation outcomes will likely further improve the theoretical model. 相似文献
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Bailang Yu Ting Lian Yixiu Huang Xinyue Ye Zuoqi Chen 《International journal of geographical information science》2019,33(4):687-706
The population distribution grid at fine scales better reflects the distribution of residents and plays an important role in investigating urban systems. The recent years have witnessed a growing trend of applying the nighttime light data to the estimation of population at micro levels. However, using the nighttime light data alone to estimate population may cause the overestimation problem due to excessively high light radiance in specific types of areas such as commercial zones and transportation hubs. In dealing with this issue, this study used taxi trajectory data that delineate people’s movements, and explored the utility of integrating the nighttime light and taxi trajectory data in the estimation of population in Shanghai at the spatial resolution of 500 m. First, the initial population distribution grid was generated based on the NPP-VIIRS nighttime light data. Then, a calibration grid was created with taxi trajectory data, whereby the initial population grid was optimized. The accuracy of the resultant population grid was assessed by comparing it with the refined survey data. The result indicates that the final population distribution grid performed better than the initial population grid, which reflects the effectiveness of the proposed calibration process. 相似文献
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现代人文地理学的研究越来越多地关注人的时空行为,而获取个体在出行活动中的时空位置数据是研究人类时空行为的前提。受数据获取技术的限制,之前对时空行为的研究主要集中在室外空间。随着室内定位技术的出现和应用,这类研究由室外空间扩展至室内空间。室内定位技术和方法较多,但从数据的角度来看,根据数据获取中使用定位方法的不同,可将室内定位数据分为几何位置数据、指纹位置数据和符号位置数据3类。目前,基于室内定位数据的研究可以归结为以下4个方面,即:人在室内的时空分布、人在室内的移动模式、人在室内的行为习惯及属性推断、人与室内环境的交互作用。然而,总体上目前的研究还处于探索阶段,理论和方法体系尚未成熟。本文认为后续的研究中需要关注以下问题:①数据获取方面。相对于蓝牙、射频识别、红外等定位技术,“智能手机+WiFi”模式的定位系统具有覆盖范围广、成本低廉、无需专门设备支持、易与用户交互等优势,是一种最具应用前景的室内定位技术;②研究内容方面。时空行为特征的研究是基础,个体属性推断及个体与环境的相互作用形式和机理研究将是重点,多时空尺度数据融合分析是一种趋势;③科学伦理方面。室内定位涉及微观尺度人类活动的记录,隐私保护问题需要高度关注。 相似文献
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科学数据共享关键问题探索——以地球系统科学数据共享网为例 总被引:3,自引:0,他引:3
作为科学基础设施, 科学数据共享平台建设可促进科技原始性创新, 提高国家科技竞争 能力。本文回顾我国近年推动科学数据共享方面的工作, 指出科学数据共享实施过程中所遇到的 主要问题; 针对这些问题, 在共享理念、数据资源整合和平台建设三个方面探索科学数据共享今 后发展的重点和工作方法。具体结合地球系统科学数据共享网建设实践, 提出搭建科学数据交换 平台, 构建科学数据共享联盟; 将科学数据共享与科研项目相结合, 实行主动服务; 建立强大的科 学数据搜索引擎; 重视文档、信息服务等。 相似文献
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使用固定翼无人机航测丹霞山核心区长老峰游览区(航测区面积4.25 km2)获得高精度影像数据638张,用Photoscan软件拼接正射影像地图及DEM数据生产。在ArcGIS10.5软件中将正射影像图批量分割成470幅图(长和宽为100 m×100 m,比例尺为1︰1 000),在分割后的地图上目测识别并定位珍稀物种丹霞梧桐(Firmiana danxiaensis H.H.Hsue&H.S.Kiu),共获取航测区内1 515株丹霞梧桐及其位置数据,构建地理数据库。利用ArcGIS10.5的空间分析模块,将DEM数据转换成坡度和坡向数据,叠加1 515株丹霞梧桐点位置数据与DEM数据、坡度和坡向数据后进行可视化定量分析。结果显示:航测区内有71.2%的丹霞梧桐(1 078株)分布在海拔210±90 m的范围内。有68.3%(1 033株)的丹霞梧桐分布在坡度>15°的丹霞崖壁地带,与实地观察的事实相吻合。虽然,在航测区长老峰的各个坡向上都可以实地观察丹霞梧桐的分布,但定量统计表明,在南东(295株)、南(276株)、南西(244株)3个坡向上分布相对... 相似文献
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Marine flooding, particularly that associated with North Sea storm surges, has posed a recurrent threat to human use of the Thames Estuary and its shorelines. During the later Middle Ages a growing frequency of surges placed increasing burdens upon the resources of coastal communities. This is reflected in expenditure upon sea-walls and related defences and in the frequent issuing of commissions of sewers, the mechanism by which the Crown intervened in matters of flood prevention and drainage. In the era of labour shortages initiated by the Black Death of 1349, the defence of some reclaimed marshlands around the Estuary and tidal river was abandoned in a precursor of managed retreat or realignment. 相似文献
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地理视频数据模型及其应用开发研究 总被引:1,自引:0,他引:1
孔云峰 《地理与地理信息科学》2009,25(5)
讨论地理视频的基本概念和数据模型,尝试提出地理视频数据的实体-关系图,并在网络环境中进行地理视频应用开发.地理视频数据模型的核心要素是:对视频帧进行位置和语义描述,建立视频片段的轨迹图层和元数据,并在轨迹图层中扩充视频帧线性参照.通过空间参照、线性参照和语义参照将视频数据与地理数据集成,实现地理视频的查询、检索、播放和地图跟踪.以河南大学校园和开封市公路网络为例,采集地理视频数据,建立地理视频数据库,发布网络地图和视频服务,并分别采用最新的Adobe Flex框架、ArcGIS Server ADF和JavaScript Mashup方式,开发网络视频GIS应用系统.原型系统开发表明,地理视频数据模型适用于网络视频GIS开发,且在技术实现上较为简单. 相似文献