一种基于改进相似度计算的文本聚类方法

针对文本在聚类或分类时,由于数据高维稀疏导致相似度值低的问题,提出一种基于改进文本相似度计算的聚类方法.首先,利用向量空间模型VSM表示文本,采用余弦函数计算文本之间的相似度;然后,基于网络中节点的相似性传播原理,通过设置阈值找到与各个文本相似度较大的文本集合,进而使用Jaccard系数将两个文本之间相似度计算转化为两个文本集合之间的相似度计算;最后根据得到的文本相似度矩阵,利用谱聚类算法对文本进行聚类.在WebKB上的实验结果表明,与传统的K-means、谱聚类方法相比,该方法提高了聚类的准确度,召回率与F值.     

基于孤立点自适应的K-means算法

孤立点的存在使聚类中心的计算产生较大误差,影响K-means算法的聚类效果.针对该问题,引入谢林模型,使孤立点能够自动移动到其邻居所在位置,消除孤立点,同时,对K-means算法过程中的距离计算、初始聚类中心选取环节进行改进,提出基于孤立点自适应的K-means算法.该算法首先对原始数据进行归一化处理,以提高距离计算的准确性;然后,根据谢林模型的基本思想,将孤立点移动到其最近的多邻邻居;接着,由类簇的数目确定邻居样本的搜索范围,确定初始聚类中心;最后,根据移动后的数据集和初始聚类中心,进行K-means聚类.在UCI机器学习数据库中经典聚类数据集上的实验结果表明,该算法可显著提升聚类的精度,同时,簇的内聚性也比较好.     

大数据挖掘中的MapReduce并行聚类优化算法研究

为了有效解决云计算环境下海量数据的并行聚类问题,以典型的基于距离的Kmeans聚类算法为例,提出了一种MapReduce并行聚类优化算法.首先将差分进化算法与K-means算法相结合,从而利用差分进化算法的强大全局搜索能力克服典型K-means算法对初始中心较为敏感的缺点,利于增强全局最优解的稳定性.然后把优化后的算法在Hadoop的Map Reduce框架下做了并行化的设计.实验结果表明,与其他多种分布式设计相比,提出的并行聚类优化算法能够在保证聚类效果的前提下,大大减少了运算的时间,提高了大规模数据的聚类效率.     

基于部分实例重判的二分K-means算法

针对二分K-means算法存在的误判实例无法再参与后续划分并降低了聚类的精度的问题.提出一种基于部分实例重判的二分K-means算法,通过区分目标簇和候选簇,过滤出候选簇中的召回实例,对召回实例所应归属的簇进行重判,实现了误判实例的正确聚类.实验结果表明,改进算法对三个实验数据集都是有效的,在不同程度上提高了聚类的准确性,同时对算法的运行速度也有小幅度的提升.     

一种面向医学短文本的自适应聚类方法

针对电子病历中疾病诊断文本同义词识别和命名标准化问题,提出了一种自适应的文本聚类方法.首先提出了一种新的基于集合的文本相似性度量算法;然后采用基于相似度分布的文本聚类算法实现同义文本识别,该算法能够自动确定类簇个数;最后采用基于序列模式的中心概念提取算法实现了疾病命名的标准化,同时对聚类簇进行合并和优化,进一步提升了聚类的准确性.测试结果表明,所述方法具有较高的准确率和聚类效率,在病历文本的预处理、分类和分析中具有广泛意义.     

基于词向量和EMD距离的短文本聚类

短文本聚类在数据挖掘中发挥着重要的作用,传统的短文本聚类模型存在维度高、数据稀疏和缺乏语义信息等问题,针对互联网短文本特征稀疏、语义存在奇异性和动态性而导致的短文本聚类性能较差的问题,提出了一种基于特征词向量的文本表示和基于特征词移动距离的短文本聚类算法。首先使用Skip-gram模型(Continuous Skip-gram Model)在大规模语料中训练得到表示特征词语义的词向量;然后利用欧式距离计算特征词相似度,引入EMD(Earth Movers Distance)来计算短文本间的相似度;最后将其应用到Kmeans聚类算法中实现短文本聚类。在3个数据集上进行的评测结果表明,效果优于传统的聚类算法。     

基于类内和类间距离的粗粒度并行AP聚类算法

近邻传播(Affinity Propagation,AP)聚类是基于数据点间消息传递的算法,主要通过数据间的相似度实现聚类.与传统的聚类方法相比,AP聚类无需事先给定聚类数目就可实现聚类,因此具有快速高效的优点,然而在处理高维复杂数据集时存在随着聚类效率提升而准确度不高的问题.为改善AP聚类算法的效率和精度,提出基于类内和类间距离的粗粒度并行AP聚类算法——IOCAP.首先引入粒度思想将初始数据集划分成多个子集;其次对各子集结合类内和类间距离进行相似度矩阵的改进计算,最后基于MapReduce模型实现改进后的并行AP聚类.在真实数据集上的实验表明,IOCAP算法在大数据集上有较好的适应性,能在保持AP聚类效果的同时有效地提升算法精度.     

基于预聚类的潜在语义分析模型文献检索研究

提出一种基于预聚类的潜在语义文献检索算法.首先,对待检索文档集进行预聚类,在潜在语义分析方法的基础上采用k-means聚类算法,寻找出各聚类簇的中心点;其次,在检索时,通过计算查询向量与各聚类簇中心点的相似度来进行检索.此方法有效解决了现有潜在语义文献检索算法在检索时需耗费大量时间计算查询向量与各文本向量之间的相似度的不足.另外还针对文献检索的特点,重新给出特征权重计算方法.实验结果表明,该方法缩短了检索的时间,提高了检索的效率.     

基于半监督的K-means聚类改进算法

针对原始K-means算法的一系列问题,提出一种基于半监督的K-means聚类改进算法,能够自动进行聚类,找出最优K值,并且最大限度地找出孤立点.首先根据样本集自身的特点,按照"类内尽可能相似"原则一步一步形成数据集,然后对数据集进行"去噪"与合并相似簇,最后,利用少量的标记信息指导和修正聚类结果.在UCI的多个数据集...     

一种高维分类型数据的子空间聚类算法

子空间聚类是一种将搜索局部化在相关维上进行的聚类算法,它能有效地克服数据因维度过高引起的在全空间上聚类的困难.针对高维分类型数据,本文提出了一种自底向上的子空间层次聚类算法,该算法在全局范围内建立一个最相似线性表用来记录每个簇类与其最相似的簇类的相似度,在聚类过程中,选取最相似的簇类合并,并通过维护此线性表产生最相似的簇类.此算法在基于信息熵的意义上能够较准确地搜索簇类的子空间.通过Zoo和Soybean两个典型的分类型数据实验发现,相对于其它相关聚类算法,该算法在聚类的准确率和稳定性方面表现出较高的优越性.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with