一种改进的概念语义相似度计算方法

针对当前概念相似度计算的片面性和不完善性等不足,提出一种改进的基于语义距离的概念间语义相似度计算方法。从有向边包含的信息量、有向边的类型以及概念密度3个方面对语义距离进行扩展,将语义距离转换成语义相似度,通过引入不对称因子,使最终概念语义相似度计算更加精确。将该方法与基于信息量方法、基于距离方法及人的主观判断结果进行比较,验证了该方法的可行性和有效性。     

一种RDF图的语义相似性度量方法

在资源描述框架(RDF)图的语义相似性度量过程中,结构相似性和语义相似性计算不精确。针对该问题,提出结构语义(SAS)方法。结合改进的基于网络距离模型的语义距离公式、基于信息量模型的权重度量机制,计算概念节点的语义相似度,完善RDF图语义相似度算法,分析结构、深度和密度对RDF图语义相似性度量的影响。设计并实现原型系统,实验结果表明,该方法可有效保证RDF图的语义相似度与实际相符。     

基于医疗本体的语义相似度评估方法

为了能够正确地理解医疗概念和精确地分析临床记录,提出了一种基于概念信息量的方法来衡量概念之间的语义相似度.引进了计算概念信息量的算法,从医疗本体的分类知识中来计算概念的信息量.介绍和分析了常用的语义相似度算法,根据概念的信息量来重定义这些语义相似度算法,产生新的基于概念信息量的语义相似度算法.通过使用一个医疗术语的评估标准和一个标准的医疗本体来评估和比较这些算法.实验结果表明,相比常用的语义相似度算法,重定义后的算法有效地改善了概念相似性评估的准确性.     

一种基于本体的语义相似度算法研究

在研究目前比较经典的基于语义距离的相似度算法的基础上,通过分析语义概念的其他关键因子,增加了节点密度以及概念属性对语义相似度的影响,提出了一个更为规范的相似度算法。通过实验分析证明,改进后算法所得相似度值更加合理,在一定的调节参数下,与人类主观判断的兼容度比原始算法提高了约15％。     

面向教学资源查询的语义相似度和相关度算法

在基于距离的语义相似度计算方法的基础上,综合多种因素对相似度的影响,提出一种新的相似度和相关度计算方法。将其应用到教学资源领域本体,计算本体概念间的相似度和相关度。实验结果显示该算法可以提高传统基于距离的相似度算法的性能。最后比较了利用该算法的语义查询与传统关键字查询的结果。     

基于HowNet的信息量计算语义相似度算法

语义相似度计算的应用范围广泛,从心理学、语言学、认知科学到人工智能都有其应用.提出了仅依赖于知网(HowNet)的信息量计算来估计两个词汇间的语义相似度.经实验证明,相比于传统的基于词网(WordNet)和大型语料库的计算信息量来估计语义相似度的算法,本文的算法更容易计算,并更接近于人工的语义相似度判断.     

一种基于WordNet的混合式语义相似度计算方法

语义相似度的计算是自然语言处理中的重要研究内容,在过去几十年的研究工作中,已有大量的语义相似度计算方法被提出并广泛应用于语义消歧、文本聚类等领域中。基于WordNet本体,改进了信息量IC计算模型,进而提出了两种混合式的语义相似度的计算方法。实验结果表明,由于同时考虑了概念节点在WordNet中的最短路径距离和IC语义距离,所提方法优于已有方法,其计算结果更加接近人类的主观判断。     

基于语义相似度的本体概念更新方法研究

为了实现本体概念的自动更新,减少对领域专家的过多依赖,给出一种基于语义相似度的本体概念更新方法 SSOCUM(Semantic Similarity-based Ontology Concept Update Method)。实现一种改进的基于Word Net的相似度算法,该算法在计算路径长度的基础上,综合考虑了概念的节点深度以及信息量对相似度的影响。为了弥补基于Word Net的相似度算法没有考虑概念属性所携带的语义信息的不足,加入属性相似度对其进行调整。通过实验对比,验证了改进算法的计算结果与标准数据集之间的皮尔森系数高于传统算法,计算结果更接近于人的主观判断。采用构建好的煤矿领域通风系统本体对SSOCUM算法进行实验分析。结果表明,SSOCUM算法有助于本体新概念的自动添加,并具有一定的准确性和有效性。     

基于语义相似度的Web服务匹配研究

现有的语义Web服务匹配算法没有考虑到本体概念间的多元关系,导致概念的语义不能被完整地反映出来,从而影响了算法的匹配性能。利用本体概念间的多元关系定义了一种语义距离,并通过该语义距离给出了概念间的语义相似度计算方法,在此基础上提出基于语义相似度的Web服务匹配算法。该算法通过本体概念间的语义相似度来反映Web服务的匹配程度。最后,通过对比实验验证了该算法的可行性和有效性。     

基于本体的概念语义相似度度量

针对概念语义相似度度量问题,提出结合基于图理论和信息量2种方法的语义相似度度量算法。计算2个概念在概念图中连接的路径长度、局部密度以及在连接2个概念之间的路径上连接关系的连接力度,结合连结路径权重和信息量来度量概念之间的语义相似度。实验结果表明,该算法能取得较好的度量效果。     

Web服务匹配中基于语义距离的概念相似度计算方法的改进

在Web服务匹配中,基于语义距离的概念相似度计算方法居于重要的地位。因现有基于语义距离的概念相似度计算方法未考虑语义不对称性和语义密度的影响,导致计算结果不够准确。为提高概念相似度计算的准确性,在现有研究的基础上,通过增加不对称因子和密度因子,对基于语义距离的概念相似度计算方法加以改进。最后通过算例对改进后的方法的可行性进行了验证,经对比分析表明改进后的方法更真实地反映了概念间的语义关系,计算结果更加符合客观实际。     

Combining multi-visual features for efficient indexing in a large image database

The optimized distance-based access methods currently available for multidimensional indexing in multimedia databases have been developed based on two major assumptions: a suitable distance function is known a priori and the dimensionality of the image features is low. It is not trivial to define a distance function that best mimics human visual perception regarding image similarity measurements. Reducing high-dimensional features in images using the popular principle component analysis (PCA) might not always be possible due to the non-linear correlations that may be present in the feature vectors. We propose in this paper a fast and robust hybrid method for non-linear dimensions reduction of composite image features for indexing in large image database. This method incorporates both the PCA and non-linear neural network techniques to reduce the dimensions of feature vectors so that an optimized access method can be applied. To incorporate human visual perception into our system, we also conducted experiments that involved a number of subjects classifying images into different classes for neural network training. We demonstrate that not only can our neural network system reduce the dimensions of the feature vectors, but that the reduced dimensional feature vectors can also be mapped to an optimized access method for fast and accurate indexing. Received 11 June 1998 / Accepted 25 July 2000 Published online: 13 February 2001     

Watersnakes: energy-driven watershed segmentation

The watershed algorithm from mathematical morphology is powerful for segmentation. However, it does not allow incorporation of a priori information as segmentation methods that are based on energy minimization. In particular, there is no control of the smoothness of the segmentation result. In this paper, we show how to represent watershed segmentation as an energy minimization problem using the distance-based definition of the watershed line. A priori considerations about smoothness can then be imposed by adding the contour length to the energy function. This leads to a new segmentation method called watersnakes, integrating the strengths of watershed segmentation and energy based segmentation. Experimental results show that, when the original watershed segmentation has noisy boundaries or wrong limbs attached to the object of interest, the proposed method overcomes those drawbacks and yields a better segmentation.     

一种高效的多变量时间序列相似查询算法

为了高效地执行多变量时间序列（MTS）相似查询,提出一种基于距离的索引结构（Dbis）相似查询算法。采用主成分分析方法对MTS数据进行降维处理;聚类MTS主成分序列,选择每类质心作为参考点;依据参考点将每类变换到一维空间,这样可以利用B+ 树结构进行索引查询;MTS序列比较相似采用的是扩展的Frobenius范数（Eros）。通过对股票数据集实验验证了Dbis算法的高效性。     

Mining Projected Clusters in High-Dimensional Spaces

Clustering high-dimensional data has been a major challenge due to the inherent sparsity of the points. Most existing clustering algorithms become substantially inefficient if the required similarity measure is computed between data points in the full-dimensional space. To address this problem, a number of projected clustering algorithms have been proposed. However, most of them encounter difficulties when clusters hide in subspaces with very low dimensionality. These challenges motivate our effort to propose a robust partitional distance-based projected clustering algorithm. The algorithm consists of three phases. The first phase performs attribute relevance analysis by detecting dense and sparse regions and their location in each attribute. Starting from the results of the first phase, the goal of the second phase is to eliminate outliers, while the third phase aims to discover clusters in different subspaces. The clustering process is based on the K-means algorithm, with the computation of distance restricted to subsets of attributes where object values are dense. Our algorithm is capable of detecting projected clusters of low dimensionality embedded in a high-dimensional space and avoids the computation of the distance in the full-dimensional space. The suitability of our proposal has been demonstrated through an empirical study using synthetic and real datasets.     

A point symmetry-based clonal selection clustering algorithm and its application in image compression

To cluster data set with the character of symmetry, a point symmetry-based clonal selection clustering algorithm (PSCSCA) is proposed in this paper. Firstly, an immune vaccine operator is introduced to the classical clonal selection algorithm, which can gain a priori knowledge of pending problems so as to accelerate the convergent speed. Secondly, a point symmetry-based similarity measure is used to evaluate the similarity between two samples. Finally, both kd-trees-based approximate nearest neighbor searching and k-nearest-neighbor consistency strategy is used to reduce the computation complexity and improve the clustering accuracy. In the experiments, first of all, four real-life data sets and four synthetic data sets are used to test the performance of PSCSCA. PSCSCA is also compared with multiple existing algorithms in terms of clustering accuracy and convergent speed. In addition, PSCSCA is applied to a real-world application, namely natural image compression, with good performance being obtained.     

Web文档聚类中k-means算法的一种改进算法

文章介绍了Web文档聚类中普遍使用的基于分割的k-means算法,分析了k-means算法所使用的向量空间模型和基于距离的相似性度量的局限性,从而提出了一种改善向量空间模型以及相似性度量的方法。实验表明,改进后的k-means算法不仅保留了原k-means算法效率高的优点,而且具有更高的准确性。     

一种综合事件本体相似度计算方法

事件本体相比于传统本体具有更加丰富的语义信息,在面向事件的大数据集成中更具优势,然而用传统的本体相似计算方法计算事件本体相似度存在很多不足,提出了一种综合的事件本体相似度计算方法。该方法以词语相似度、集合相似度、层次结构相似计算为基础,然后从事件类名称、事件类要素、事件类层次结构和非层次结构讨论事件本体的相似度,最终获得事件本体的综合相似度。实验表明该方法相比传统本体相似度计算方法准确率更高,语义信息更加丰富。