海上溢油遥感图像的边缘检测算法研究.pdf

河北大学
硕士学位论文
基于本体术语关系的SBN检索模型扩展
姓名:田晋坤
申请学位级别:硕士
专业:计算机应用技术
指导教师:徐建民
2011-05
摘要
摘要
贝叶斯网络检索模型是信息检索中概率模型中的一种。合理使用术语关系扩展该检
索模型可以有效地提高检索性能。本体是共享的概念模型的形式化的规范说明,具有概
念层次结构和逻辑推理功能。使用本体可以比较准确的获得术语间关联关系。
本文将 SBN 模型中的单术语层-文档层双层结构扩展为双术语层-文档层三层结构,
通过本体获得两层术语间的关联关系,使用基于本体的术语关联度计算方法计算两层术
语间的关联度,给出了扩展模型各层节点的概率估计以及检索模型的推理机制。在实验
中,本文首先使用骨架法建立了 5 个不同主题的本体实例,每个本体实例包含 10-20 个
术语;再通过基于本体的术语关联度计算方法获得所有术语间的关联度;然后使用小型
中文测试集作为测试数据,从中抽取 5 个查询主题用于原始的 SBN 检索模型和扩展 SBN
检索模型的检索;最后使用内插法获得两组检索结果的查全率与查准率并对扩展模型的
每一步数据进行分析。实验结果表明,与原始 SBN 检索模型相比,基于本体术语关系
扩展的 SBN 检索模型具有更好的检索性能。

关键词本体术语关系术语关联度贝叶斯网络
I
Abstract
Abstract
The work Retrieval Model is one of the probability models in information
retrieval. By extending this retrieval model with reasonable relations of terms, the retrieval
function may be enhanced effectively. The ontology refers to the formalized specification of a
shared conceptual model which possesses both the conceptual layered structure and the
logical reasoning function. Based on ontology, the relationship among terms can be accurately
obtained.
This thesis first extends the double-layer structure of SBN (Sample work)
model, comprising 1 single term layer and 1 document layer, into a three-layer structure
comprising 2 term layers and 1 document layer; and then obtains the relationship between 2
term layers through the ontology and calculates the relative degree between the terms of both
layers by means of ontology-based method; and finally gives the probability estimate of all
the layer nodes of the extended model as well as the reasoning mechanism of the retrieval
model. In the experiment, this thesis first of all builds up 5 instances of ontology with
different themes by skeletal methodology, each containing 10 to 20 terms; and then obtains
the relative degree among all the terms by ontology-based calculating method for term
relative degree. After that it takes the small Chinese test collections as the testing data