首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 93 毫秒
1.
基于XML内容和结构的模糊查询   总被引:1,自引:0,他引:1  
用户在查询XML文档的时候经常有模糊的或者不精确的查询要求.为了解决用户的模糊查询意图,提出了一种基于XML内容和结构的模糊查询方法.以模糊集理论为基础,提出了利用模糊谓词实现XPath查询表达式的模糊扩展,采用模糊查询松弛方法,它可以产生更多满足用户查询要求的结果.在排序这些查询结果的时候,提出的打分方法使用一个扩展的向量空间模型,考虑了内容和结构的相关性,按照内容和结构的匹配情况打分,得分大于阈值的节点就是答案节点.最后,通过实验验证了所提方法的有效性.  相似文献   

2.
针对信息搜索与挖掘中存在的关键词多义性及用户对所要查询信息的分类存在一定的模糊性问题,提出了一种基于模糊分类网络的信息挖掘方法。该方法利用模糊分类网络固有的对模糊信息的非线性处理能力和自适应学习机制,通过对WEB页面大量分类文档信息的学习,建立了基于模糊分类网络的信息分类器和挖掘模型。构造的信息分类模型结构简单、学习收敛速度快且易于实现。文中给出了分类策略和实现算法,并以中国石油网油气管道专题信息分类为例验证了方法的有效性。  相似文献   

3.
在关系数据库环境下表示决策表为利用已成熟的数据库技术和功能去操作决策表提供了一种机制。决策表的查询可以通过传统的数据库查询来实现。本文讨论了如何利用相关的方法去表示、存储和管理模糊决策表知识,进而可以利用扩展的SQL功能进行模糊决策。  相似文献   

4.
随着市场竞争的加剧和信息社会需求的发展,从大量数据中提取(检索、查询等)用于决策和分析的信息就显得越来越重要.通过会计数据仓库设计、会计数据抽取、会计数据维护、会计决策需求设计、挖掘算法设计,以及挖掘操作、结果表达和解释等,可以从海量的财务数据中发掘有用的、重要信息组合,为企业发展、领导决策等提供科学的技术支持.  相似文献   

5.
ASP(Active Server Pages)是一种服务器端的脚本语言,是一种新的应用软件服务模式。本文阐述了如何将SQL表达自然语言中部分模糊概念的能力通过ASP应用到网络环境下,提出了两种基于模糊查询的方法(Select命令法和存储过程法),并设计出了良好的查询工具。  相似文献   

6.
提出了一种使用SQL查询设计模糊控制器的算法.文中重点介绍了模糊控制器设计原理和利用SQL设计模糊控制器的过程,并给出了在VB编程环境中实现的实例.  相似文献   

7.
一种基于知识的关系数据库模糊查询方法   总被引:1,自引:0,他引:1  
在数据库查询中,针对传统DBMS不支持模糊查询的弱点,提出了基于知识的数据库模糊查询转换方法.以模糊集理论为基础,介绍了数据库模糊查询条件的构成形式,并提出利用隶属函数、领域知识和模糊集的α-截集运算相结合的方法实现模糊查询转换,模糊查询条件的转换和扩展考虑了查询条件的重要程度和用户偏好.该方法无需改变传统SQL语言或数据库引擎就能够实现模糊查询,提高了用户与系统之间的交互能力.  相似文献   

8.
 以数据、预案、模型、知识、决策方法存储和使用为核心的公共安全数据中心是由存储设备、网络设备、应用数据和应用程序综合集成,它具有存储、查询、管理和维护等功能。根据应急平台的需求,数据中心采用“层次+混合”的方法进行数据中心体系结构的设计。在数据中心的核心层,数据、预案、模型、知识、决策方法按一定的结构“混合”在一起。设计数据中心的结构,实现各类数据的集成和管理,为应急平台的各种应用提供有效的访问。  相似文献   

9.
基于模糊粗糙集理论的信息检索方法的研究   总被引:2,自引:0,他引:2  
信息检索中的词汇挖掘就是利用给定域范围的词汇来提高用户查询效率,大多数情况下信息检索系统上的查询不是优化的。词汇挖掘可以使我们在查询上进行泛化、特化或者其他基于词汇转换的操作来提高查询性能。本文将粗糙集和模糊集理论结合起来研究了一种新的词汇挖掘框架,该框架即使当文本和查询使用加权表示即模糊表示时,也可以用基于粗糙集的近似集合。  相似文献   

10.
XML查询语言XQuery的分析与研究   总被引:1,自引:0,他引:1  
李元韬  曹志宇 《太原科技》2010,192(1):90-92
随着XML日益广泛的应用,XML的查询语言XQuery变得尤为重要。阐述了XML的查询语言XQuery.设计并实现了一个基于XQuery的XML查询系统,同时介绍了它的结构框架和执行过程,提出了对其查询优化的具体方案。  相似文献   

11.
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.  相似文献   

12.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

13.
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。  相似文献   

14.
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  相似文献   

15.
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  相似文献   

16.
17.
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.  相似文献   

18.
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).  相似文献   

19.
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.  相似文献   

20.
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.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号