An Oracle8i-based approach is proposed to manage the integrated databases oflarge CyberCity. This approach consists of three schemes: ① a special R+-tree index is designed toaccelerate spatial retrieving, in which th...An Oracle8i-based approach is proposed to manage the integrated databases oflarge CyberCity. This approach consists of three schemes: ① a special R+-tree index is designed toaccelerate spatial retrieving, in which the bounding boxes of local regions have no intersection andall leaf nodes of the R+-tree (geometry records ) have no repetition; ② different data compressionalgorithms are adopted to compress the digital elevation models, 3D vector models and images, suchas LZ77 lossless compression algorithm for compression of vector data and JPEG compressionalgorithms for texture images; ③ in order to communicate with Oracle8i database, a CyberCity GIS.spatial database engine (SDE) is designed. On the basis of this SDE prototype a case study is done.展开更多
针对社交网络以及社交用户关注主题,分析用户所在位置,在社交网络的基础上提出主题推荐模型即location-themesocial model(LTS M odel).文章主要从三个方面进行了分析,首先对主题进行分类,运用余弦相似性算法构建向量空间主题模型.其次,...针对社交网络以及社交用户关注主题,分析用户所在位置,在社交网络的基础上提出主题推荐模型即location-themesocial model(LTS M odel).文章主要从三个方面进行了分析,首先对主题进行分类,运用余弦相似性算法构建向量空间主题模型.其次,在MapReduce框架下根据位置快速构建R*-tree索引,建立空间模型,在此基础上找到基于位置和主题的社交网络模型.最后,使用标准数据集对算法进行测试,并根据准确率、召回率和F1值对其效果进行评价.R*-tree索引算法采用抽样方法快速确定空间划分函数,保证了数据对象均匀地划分到各个分区.余弦相似性算法能够快速准确地找到相似主题,并且敏感识别度较强.实验证明基于LTS Model的位置—主题推荐算法(LTRA)能够快速找到满足用户兴趣的主题并进行推荐.展开更多
基金Project supported by the National Key Basic Research and Development Program (No. 2002CB312101) the National Natural Science Foundation of China (No.40001017).
文摘An Oracle8i-based approach is proposed to manage the integrated databases oflarge CyberCity. This approach consists of three schemes: ① a special R+-tree index is designed toaccelerate spatial retrieving, in which the bounding boxes of local regions have no intersection andall leaf nodes of the R+-tree (geometry records ) have no repetition; ② different data compressionalgorithms are adopted to compress the digital elevation models, 3D vector models and images, suchas LZ77 lossless compression algorithm for compression of vector data and JPEG compressionalgorithms for texture images; ③ in order to communicate with Oracle8i database, a CyberCity GIS.spatial database engine (SDE) is designed. On the basis of this SDE prototype a case study is done.
文摘针对社交网络以及社交用户关注主题,分析用户所在位置,在社交网络的基础上提出主题推荐模型即location-themesocial model(LTS M odel).文章主要从三个方面进行了分析,首先对主题进行分类,运用余弦相似性算法构建向量空间主题模型.其次,在MapReduce框架下根据位置快速构建R*-tree索引,建立空间模型,在此基础上找到基于位置和主题的社交网络模型.最后,使用标准数据集对算法进行测试,并根据准确率、召回率和F1值对其效果进行评价.R*-tree索引算法采用抽样方法快速确定空间划分函数,保证了数据对象均匀地划分到各个分区.余弦相似性算法能够快速准确地找到相似主题,并且敏感识别度较强.实验证明基于LTS Model的位置—主题推荐算法(LTRA)能够快速找到满足用户兴趣的主题并进行推荐.
