基于网页分割的语义信息检索研究

如何准确表达用户意图,判断网页与用户需求的相关性是信息检索技术研究的重要方向。本文提出了一种基于网页内容分割的语义信息检索算法。该算法根据网页半结构化的特点,按照HTML标记和网页的内容将网页进行区域分割。在建立HTML标记树的基础上,利用内容相似性和视觉相似性进行节点的整合。根据用户的查询,充分利用区域信息来对相关的检索结果进行排序。实验表明,本文提出的方法可以显著地提高搜索引擎的查询效果。     

一种编辑距离算法及其在网页搜索中的应用

针对传统方法不能很好地处理网页中简短域与用户查询之间的相关性排序问题,提出一种基于改进的编辑距离排序算法.将以词为单位的用户查询和简短网页域通过匹配编码转化为2个字符串,再利用改进的编辑距离计算2个字符串之间的相似性.由于在用户查询与待比较的简短网页域之间引入了查询词分布的位置、顺序和距离等,以及含有查询词修饰关系的重要信息,所以编码字符串之间的相似程度可以衡量对应的查询与简短网页域之间的相关性.经大规模真实搜索引擎实验表明,该算法较之传统的相关性排序算法,可以显著地提高网页搜索中的简短网页域相关性排序性能,尤其适用于简短域与用户查询之间的相关性比较.     

一种基于关键词的网页搜索结果多样化方法

网页搜索结果的多样化已经逐渐成为提高网页搜索效率和用户满意度的一个重要因素.文中将多样化问题形式化为信息面覆盖率的最大化问题,提出了一种基于关键词的网页搜索结果多样化方法KDM.该方法首先从与用户查询相关的结果文档中提取出可以描述结果文档所蕴含的信息面的关键词,然后根据关键词的同现性以及关键词对文档的描述能力,计算出结...     

基于动态学习的Deep Web数据源选择算法

提出了基于查询过程的动态计算数据源和查询关键词相似度的算法.当用户查询时,从数据源中选择子集进行查询,然后计算结果网页与查询关键词的相似度,按加权均值法调整该数据源的相似度,随着系统的运行,数据源与关键词的相似度不断被动态调整以反映数据源的实际情况,从而为数据源选择做出判断依据.     

基于内容相关性挖掘的反馈式搜索引擎框架

当前主流的搜索引擎根据查询词在网页中的出现频率,辅以网页权威性等信息,生成查询结果．但用户提供的查询词往往非常简单,因此搜索引擎难以确定用户的查询意图．为此,给出了一种利用海量clickthrough数据进行网页内容相关性挖掘的方法,在此基础上给出了一种反馈式搜索引擎（FSE）框架及相关算法．FSE根据网页相关性动态生成查询结果,以期提供给用户更中肯和个性化的信息．基于真实点击数据,进行了网页相关性矩阵的压缩实验和有效性实验,证明了该框架的可行性．     

基于语义联系的新闻网页关键词抽取

提出一种基于语义联系的新闻网页度,还考虑词语在具体上下文中的相关性,用词汇链将词语语义联系表示成图形式,在此基础上抽取出新闻网页关键词.对从网易网站选取120篇有核心提示的新闻网页进行测试,实验结果表明,所提出的方法比基于词频的关键词抽取方法和基于<知网>语义相似度构建词汇链的关键词抽取方法,在准确率和召回率上有很大的提高,当抽取关键词个数为3时,比基于词频方法的准确率和召回率分别提高了27.77%和21.38%.     

基于网页关键词的个性化Web推荐算法

个性化Web推荐系统是利用用户的浏览行为定制符合用户结构和内容的过程。在综合应用协作过滤和内容过滤方法的基础上,通过对网站网页关键词的评估,提出了一种新的个性化Web推荐算法,研究了基于网页关键词的个性化模型,网站页面中关键词的权重计算,基于协作过滤的新用户推荐,基于内容过滤的再次推荐方法,以及基于用户群的用户兴趣调整方法。实验证明,本算法能够以较高的效率对用户进行网页推荐。     

基于用户兴趣及术语间关系的查询扩展方法

针对传统查询扩展方法无法根据不同用户的需求进行检索的不足,提出一种基于用户兴趣和术语间关系进行查询扩展的方法。通过对用户浏览的网页文档及得到的网页日志进行挖掘得到一系列代表用户兴趣的术语,根据与初始查询词存在同义关系的用户兴趣术语及其权重对初始查询词权重进行调整,利用兴趣术语中与初始查询词存在本体关联关系的术语对初始查询进行扩展。实验结果表明,该方法相对于传统查询扩展方法在一定程度上提高了信息检索的查全率和查准率。     

基于模型匹配的Deep Web数据库分类

提出一种基于模型匹配的深网（Deep Web）在线专业数据库查询接口特征抽取方法, 该方法通过分析网页结构中特征词的深度自动抽取查询接口特征向量, 同时考虑频度和集中度两种因素定义特征词向量空间中的权值, 并在传统向量模型的基础上加入特征词个数作为一个新的分量, 构建一个数据库查询接口, 使用模型匹配的分类方法对其进行分类. 实验验证了该方法的有效性.     

语义词库关联的藏文Web语义检索系统研究与实现

文章依据所抓取的大量藏文网页URL,对相关的藏文信息网页进行除噪去重处理,得到较为完善的藏文信息库。对用户要查询的藏文信息进行预处理和藏文语义标注,通过基于本体的词汇相关性算法,扩展藏文的查询词汇,建立一对多的藏语词汇联系,从而实现藏文查询中的相关性检索,得到更加符合用户需求的语义关联网页信息。     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.