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在个性化推荐系统中,项目的内容特征是影响推荐精度的重要因素。针对传统协同推荐不能有效考虑项目内容特征的问题,在考虑传统用户-项目评分信息的基础上,引入项目的内容特征属性,构建基于多示例(MI)的用户评分信息表达模型。根据多示例学习模式具有一定容错性的特点,设计了基于多示例聚类的协同推荐算法,通过多示例聚类计算用户的最近邻集合,根据最近邻集合对用户评分进行预测。实验结果表明,基于MI聚类的协同过滤推荐算法提高了预测评分的准确度,且有效缓解了数据稀疏性问题 相似文献
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群体用户对公共地图服务的访问行为具有社会性,存在着一定的群体访问行为模式。该模式具有高强度的访问聚集性与突发性,且决定着公共地图服务对云计算资源的需求。如何有效地表达和捕捉群体用户访问聚集性及其访问强度的时序变化特征,进行准确的公共地图服务负载预测,是实现按需选择和调度云计算资源,应对海量用户并发服务挑战的关键。本文基于海量的公共地图服务用户访问日志和时间序列聚类方法,建立了群体用户访问到达行为的时序分布模型;考虑降低负载预测复杂度的同时,利用访问强度具有多峰值、变强度以及周期性的特点,分割访问到达率在一个周期内时间序列上的模式区间,实现访问强度时序聚类划分的最优;基于各访问模式区间不同的访问到达概率密度的分布,提出了基于累积概率分布的时间序列平滑预测服务负载方法,该预测方法的算法复杂度低,且所需的先验数据量小。实验证明,本文提出的基于时序的群体用户访问到达率最优分割方法及其预测方法可以以较高的准确率预测服务负载。该方法在应对海量用户并发访问挑战的同时,可提高云计算资源的利用效率,解决公共地图服务质量与服务成本的平衡性问题。 相似文献
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对现有的Web服务分类方法中存在的问题进行了分析,阐述了流形和流形学习的概念以及将流形学习引入到Web服务领域的目的,提出了利用流形学习进行空间信息服务分类的方法.该方法在空间信息服务降维前后保持各服务间的相似(近邻)关系不变,并通过对服务进行降维可视化指导,确定初始聚类数和聚类中心,从而提高利用聚类分析实现空间信息服务无监督分类的精度.实验表明,本文方法不仅能够对抽象的Web服务进行数值化表示,而且能够有效地提高服务分类的性能. 相似文献
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地理信息系统作为一种新的空间信息服务应用模式,是一个复杂的、创造的过程。地理服务资源的多样性和不确定性、应用需求的动态性和复杂性使人们难以高效、智能化地获取空间信息。本文针对地理信息空间的特点进行了评述,分析了信息流的本体关系,在地理信息服务规范的基础上,研究了基于地理数据的关联关系,建立了基于图聚类方法的空间数据关系挖掘数学模型,并运用一个实例来说明这些地理数据之间的关系情况。 相似文献
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个体位置预测在传染病精准防控、公共设施科学规划等应用中具有重要意义,既有位置预测算法主要侧重对个体纵向历史轨迹特征进行挖掘建模,从而实现位置预测,对横向相似性用户的规律特性考虑较少。因此,基于图卷积和长短期记忆模型（long short-term memory,LSTM）框架,提出顾及横向相似用户轨迹特征以及纵向历史规律性特征的个体位置预测算法。首先,构建用户轨迹相似性算法并筛选高相似度用户;然后,利用图卷积模型提取待预测用户相似高的用户轨迹特征;最后,利用LSTM框架提取历史轨迹特征,集成相似用户轨迹特征,从而实现个体位置预测。基于某市8万多个用户连续4个工作日的数据进行实验,结果表明,所提算法的准确率随预测时间步长增加而下降,而夜间预测准确率明显高于白天,但相比于既有模型均有10%以上提高;以15 min为预测时间步长时,模型准确率达80.45%。 相似文献
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SVG对矢量图形的描述与地理信息系统对现实世界的某些抽象描述一致,空间数据可以转换成SVG文档来进行存储、传输和表现。提出一种基于SVG的空间数据组织方法,并在此基础上分析了基于DOM和脚本语言的地理信息交互实现,通过一种基于SVG模版的网络地理信息服务原型及其具体实施验证了以SVG文档实现网络地理信息服务的可行性和实用性。 相似文献
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A geospatial cyberinfrastructure is needed to support advanced GIScience research and education activities. However, the heterogeneous and distributed nature of geospatial resources creates enormous obstacles for building a unified and interoperable geospatial cyberinfrastructure. In this paper, we propose the Geospatial Service Web (GSW) to underpin the development of a future geospatial cyberinfrastructure. The GSW excels over the traditional spatial data infrastructure by providing a highly intelligent geospatial middleware to integrate various geospatial resources through the Internet based on interoperable Web service technologies. The development of the GSW focuses on the establishment of a platform where data, information, and knowledge can be shared and exchanged in an interoperable manner. Theoretically, we describe the conceptual framework and research challenges for GSW, and then introduce our recent research toward building a GSW. A research agenda for building a GSW is also presented in the paper. 相似文献
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Integrating Web-based GIS and image processing tools for environmental monitoring and natural resource management 总被引：1，自引：1，他引：0
The combined powers of Web-based geographic information systems (GIS) and on-line remote sensing tools can significantly reduce the high cost and labor associated with environmental monitoring and natural resource management. This paper introduces an integrated Web-based GIS architecture by combining three levels of geographic information services (GIServices): data archive, information display, and spatial analysis. A prototype Web site, WGAT (Web-based GIS and Analytic Tools), has been developed to provide easy access of geospatial information and to facilitate Web-based image analysis and change detection capabilities for natural resource managers and regional park rangers. The Web-based integration framework emphasizes user-oriented services, distributed network environments, metadata standards, communication protocols, client/server computation, and ubiquitous access.This paper forms a portion of the Integrated Mobile GIS and Wireless Image Web Services for Environmental Monitoring and Management project supported by NASAs Affiliated Research Center (ARC) at San Diego State University. Funding by the NASA ARC program and matching funds from the San Diego State University Foundation are acknowledged and greatly appreciated. The author wishes to thank John Kaiser, the ARC program coordinator, and Dr. Douglas Stow, the ARC program Principle Investigator, for their coordination efforts on this project. Java programming was provided by Liang Guo, a geography graduate student at San Diego State University. 相似文献
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GONG Jianya WU Huayi ZHANG Tong GUI Zhipeng LI Zhenlong YOU Lan SHEN Shengyu 《地球空间信息科学学报》2012,15(2):73-84
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The quality of GIServices (QoGIS) is an important consideration for services sharing and interoperation. However, QoGIS is a complex concept and difficult to be evaluated reasonably. Most of the current studies have focused on static and non-scalable evaluation methods but have ignored location sensitivity subsequently resulting in the inaccurate QoGIS values. For intensive geodata and computation, GIServices are more sensitive to the location factor than general services. This paper proposes a location-aware GIServices quality prediction model via collaborative filtering (LAGCF). The model uses a mixed CF method based on time zone feature from the perspectives of both user and GIServices. Time zone is taken as the location factor and mapped into the prediction process. A time zone-adjusted Pearson correlation coefficient algorithm was designed to measure the similarity between the GIServices and the target, helping to identify highly similar GIServices. By adopting a coefficient of confidence in the final generation phase, the value of the QoGIS most similar to the target services will play a dominant role in the comprehensive result. Two series of experiments on large-scale QoGIS data were implemented to verify the effectivity of LAGCF. The results showed that LAGCF can improve the accuracy of QoGIS prediction significantly. 相似文献
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基于地学信息服务的Internet 3维 GIS：GeoEye 3D 总被引：9，自引：0，他引：9
随着Internet、分布式计算以及计算机图形学的飞速发展,开发基于Internet的3维GIS系统已成为可能。这3种技术的有力结合为地学领域开创了一个崭新的时代,促使网络GIS的概念由“地学数据服务”提高到“地学信息处理服务”的新阶段,不仅地学数据,地学信息处理功能也可以分布在基于客户／服务器的架构上,用户可以根据不同的需求“租用”和组合来自于Internet的不同功能。基于这一概念和作者提出的构件注册模型,我们从1998年开始着手研究和开发新一代的Internet 3维GIS：GeoEye 3D。这一系统集成了GIS、3维可视化、分布式计算及网络通信等技术,允许用户通过标准Internet浏览器来应用远程功能对远程和本地数据进行可视化分析。阐述了地学信息处理服务概念和构件注册模型以及GeoEye 3D的系统架构、算法和应用实例。 相似文献
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基于Web Services的GIS与应用模型集成研究 总被引：42，自引：1，他引：41
分析GIS与应用模型集成的研究现状及存在的问题。针对存在的问题,提出基于Web Services的GIS与应用模型集成方法。具体定义应用模型服务体系及其与空间信息服务体系的关系,讨论基于服务链的GIS-ervices与应用模型服务集成服务链样式、集成实现过程、集成开发流程,给出基于服务集成实现小流域地貌演化问题计算的服务集成分析设计与实验结果。实验结果证明本文提出的基于Web Services的GIS与应用模型集成方法正确可行。 相似文献
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采用Landsat TM数据分析了阿克苏河—塔里木河断面水质污染状况,通过波段的DN值和常规监测数据建立能反映水质状况的
污染物监测模型。结果发现,将2000年常规监测数据代入模型后,与遥感数据的结果基本吻合| 重建阿克苏河—塔里木河的连续水体
污染变化曲线,得出污染物浓度随着远离上游而增加。 相似文献
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Monitoring drought dynamics in the Aravalli region (India) using different indices based on ground and remote sensing data 总被引：5，自引：0，他引：5
C. Bhuiyan R.P. Singh F.N. Kogan 《International Journal of Applied Earth Observation and Geoinformation》2006,8(4):289-302
The hard-rock hilly Aravalli terrain of Rajasthan province of India suffers with frequent drought due to poor and delayed monsoon, abnormally high summer-temperature and insufficient water resources. In the present study, detailed analysis of meteorological and hydrological data of the Aravalli region has been carried out for the years 1984–2003. Standardised Precipitation Index (SPI) has been used to quantify the precipitation deficit. Standardised Water-Level Index (SWI) has been developed to assess ground-water recharge-deficit. Vegetative drought indices like Vegetation Condition Index (VCI) and Temperature Condition Index (TCI) and Vegetation Health Index (VHI) have been computed using NDVI values obtained from Global Vegetation Index (GVI) and thermal channel data of NOAA AVHRR satellite. Detailed analyses of spatial and temporal drought dynamics during monsoon and non-monsoon seasons have been carried out through drought index maps generated in Geographic Information Systems (GIS) environment. Analysis and interpretation of these maps reveal that negative SPI anomalies not always correspond to drought. In the Aravalli region, aquifer-stress shifts its position time to time, and in certain pockets it is more frequent. In comparison to hydrological stress, vegetative stress in the Aravalli region is found to be slower to begin but quicker to withdraw. 相似文献