一种适用于高维非线性特征数据的聚类算法及应用

针对高维数据聚类分析中数据之间具有多种非线性特征关系,导致数据分布不均、传统相似性度量失效及结果类中心难以精准表征等问题,提出了一种基于核主元分析(KPCA)与密度聚类(DBSCAN)的高维非线性特征数据聚类分析技术。首先,为有效提取高维数据的非线性特征,利用KPCA理论将原始数据映射到更高维数据空间,利用主元分析获得数据变化的方向集合,并进行降维分析;然后,通过重新定义数据样本在主元空间的相似性距离对传统DBSCAN聚类方法进行改进,并利用3δ统计理论对各簇中心的进行表征,从而实现高维数据的精确分类与类中心知识表达。以实际高血压患者群体聚类问题为例对方法进行了有效性验证,实验表明,所提方法可以有效获取原始数据的非线性特征,实现患者个体特征群体的有效划分及簇类中心知识的表达,解决传统DBSCAN聚类方法对高维数据不适用的问题。     

一种基于密度和网格的高效聚类算法

聚类已成为数据挖掘的主要方法之一,能够帮助人们在大量的数据中发现隐藏信息.目前最具典型的密度聚类算法是DBSCAN(density-based spatial clustering of applications with noise),它能够在空间数据库中很好地发现任意形状的簇并有效地处理噪声,但是它的计算复杂度相对较大.因此,采用划分数据集和聚簇合并方法,提出了一种基于密度和网格的高效聚类算法DGCA,并通过人工合成数据集和真实数据集对该聚类算法进行理论验证.实验结果表明该算法在效率性能和质量方面比DBSCAN都得到了提高.     

一种改进的DBSCAN算法

聚类技术是数据挖掘中的一项重要技术,它能够根据数据自身的特点将集中的数据划分为簇.DBSCAN是一种经典的基于密度的聚类算法,能发现任意数量和形状的簇,但需设置Eps和MinPts参数,且聚类效果对参数敏感.提出一种改进的DBSCAN算法,该算法采用自适应的Eps参数使得DBSCAN算法能对具有不同密度的簇的数据集进行聚类.仿真实验结果验证了所提算法的有效性.     

一种基于轨迹数据密度分区的分布式并行聚类方法

全球定位技术与基于位置服务的发展促进了轨迹大数据的发展.轨迹聚类作为最重要的轨迹分析任务之一,得到了广泛的研究.目前,大多数聚类方法是在单处理机模式下运行,对于大规模的轨迹数据其处理时间较长,难以满足时效性强的轨迹分析任务,为此提出一种基于轨迹数据密度分区的分布式并行聚类方法.首先将整个轨迹数据集抽象在一个矩形区域内,通过该矩形最长维度的变换将数据合理地划分为若干任务量相当的分区,构建可供分布式并行聚类的局部数据集,然后各工作服务器对局部分区分别执行DBSCAN聚类算法,管理服务器对局部聚类结果进行合并与整合.实验结果验证了本方法的有效性,在一定程度上提高了聚类分析的运算效率.     

出租车载客热点技术研究

通过挖掘北京市出租车历史轨迹数据,分析出租车载客热点区域,从而为空载行驶的出租车司机提供寻客方向.基于大数据平台的历史轨迹数据预处理,按照数据生成时间对出租车历史数据进行排序,提取历史数据中的所有乘客上车地点;使用聚类算法对提取出的上车地点进行聚类分析,提取乘客频繁出现的区域.以出租车寻找乘客为背景,分别采用基于密度的DBSCAN算法和基于距离的K-means算法对载客点进行聚类.采用聚类算法性能评估中的DB内聚指数对两种算法的聚类效果进行评估,结果显示工作日和非工作日DBSCAN算法聚类结果的内聚效果均优于Kmeans算法.     

基于DBSCAN算法的告警数据聚类研究

提出了基于DBSCAN(density-based spatial clustering of application with noise)和多约束活动窗口算法的告警时间序列预处理方法。根据原始告警数据的特点,利用DBSCAN聚类算法以时间维度将原流水告警数据划分为多个告警事件,并通过约束条件选取DBSCAN最佳输入参数,在各个时间段利用滑动时间窗口提取告警事务。实验结果表明,该方法能有效滤除单一告警事务(噪声告警)对实际事务分析的影响,提升告警事务分析的总体质量,同时可根据实际需要利用多约束条件选择最佳参数,有效提升告警事务总体分析能力。     

一种基于密度和网格的高效聚类算法(英文)

聚类已成为数据挖掘的主要方法之一,能够帮助人们在大量的数据中发现隐藏信息。目前最具典型的密度聚类算法是DBSCAN(density-based spatial clustering of applications with noise),它能够在空间数据库中很好地发现任意形状的簇并有效地处理噪声,但是它的计算复杂度相对较大。因此,采用划分数据集和聚簇合并方法,提出了一种基于密度和网格的高效聚类算法DGCA,并通过人工合成数据集和真实数据集对该聚类算法进行理论验证。实验结果表明该算法在效率性能和质量方面比DBSCAN都得到了提高。     

基于改进DBSCAN算法的激光雷达车辆探测方法

结合车辆行驶的实际环境,提出了一种基于改进DBSCAN快速聚类算法的激光雷达车辆探测方法.建立激光雷达与摄像机传感器坐标与车辆坐标之间的转换模型,进行数据融合,通过改进DBSCAN算法对雷达数据进行去噪声和聚类处理,根据车辆在激光雷达探测中的形状特征模型进行形状匹配,实时完成车辆探测,并将探测结果投影至图像上.实车实验结果证明,改进的DBSCAN算法在车辆探测应用中具有良好的准确性和实时性.     

一种改进地标点采样的不平衡数据聚类算法

对不平衡数据进行聚类分析时,K-means聚类方法可能会错误地将分布在较小区域类别中的样本划分到大区域类别中;谱聚类算法,虽然可以有效优化数据结构,并很好地识别不同形状的样本,但却难以处理大规模数据.针对这些问题,提出一种改进地标点采样的不平衡数据聚类算法.该算法首先对不平衡数据进行预聚类以获得初始类标签,然后基于数据密度对数据进行采样.在此基础上,通过对采样数据执行K-means聚类,并将聚类中心作为地标点,对数据进行谱聚类分析.实验结果显示,该方法在处理不平衡数据时,不仅能够有效提高样本的聚类准确率,而且能够保证聚类结果的稳定性和精度.     

考虑对象方向关系的密度聚类算法

 聚类分析是数据挖掘的一个重要研究方向.为了在大规模空间数据库中发现任意形状的聚类,Martin Ester等提出基于密度的聚类算法DBSCAN.针对DBSCAN处理聚类边界对象的不足,提出了聚类时考虑对象方向关系的改进算法,实验表明,改进算法在不改变时间、空间复杂度的情况下能得到更好的聚类结果.     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

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