联机分析处理与关联规则挖掘的集成化模型研究

通过分析关联规则挖掘和联机分析处理(OLAP)的特点,提出了一种联机分析处理与关联规则挖掘的集成化模型,并给出了其代数结构描述;在此基础上,提出了一种基于OLAP的关联规则挖掘理论,从而为简化挖掘步骤,提高挖掘效率奠定了理论基础;使用超市的实际数据进行实验分析,验证了该模型及其挖掘理论的正确性和可行性.     

一种基于星型模型的增量更新算法

在进行数据仓库的OLAP联机分析处理时,通常采用预先聚集(Aggregate)操作生成概括数据的方法提高查询效率;但是,基于星型模型的数据仓库中的维表的纠错改变和自然改变将会引发概括数据的不正确问题.本文通过研究星型模型维表及其变化的特点,提出了一种增量更新算法,在几乎不增加空间的情况下,降低时间复杂度的增量更新;并通过性能验证,分析算法的可行性.     

面向OLAP应用的OceanBase模式设计

随着大数据时代的来临,用户查询需求也越来越复杂,对数据库的可扩展性和SQL查询效率都提出了很高的要求.OceanBase是Alibaba研发的适应互联网规模的关系型分布式数据库,能够做到可扩展、低成本、高可用,并能应用到很多业务场景,包括OLTP和OLAP.然而,当前发布的最新OceanBase只支持主键索引,还不能支持二级索引.其次,OceanBase在连接上没有并行处理,使得查询效率较低.因此,为了能够使用主键索引及减少连接来加快查询速率,OceanBase模式设计是必要的.本文主要以TPC-H的22个查询为OLAP的研究案例,分析传统数据库的模式设计,并提出OceanBase分布式数据库下的模式设计规则,最后将会通过实验来验证这套模式设计规则的有效性.     

基于Spark/Shark的电力用采大数据OLAP分析系统

用电信息大数据上的OLAP查询涉及数据量大,具有多表连接操作频繁、SQL结构复杂等特点,传统关系型数据库面对该类应用,表现出可扩展性弱、数据写入吞吐量低与查询效率低等问题.为此设计了一套基于Spark/Shark的电力大数据OLAP分析系统,该系统采用分布式文件系统HDFS保存电力用电信息采集系统的大数据,通过Shark进行前端SQL解析,Spark进行查询计算;然而,原生Shark只支持粗粒度分区,不支持细粒度的索引技术,难以高效地过滤无关数据,影响了查询性能.为克服这一不足,该系统设计了一种基于前缀树的细粒度索引结构TrieIndex,并通过数据重组技术优化了数据在HDFS的分布,提升了Shark的数据过滤能力以及用电信息大数据OLAP分析的性能.真实用电信息采集系统数据与查询的实验结果表明,该系统比关系型数据库的写入速度提升了12倍,比原生Shark的查询效率提升了10倍以上.     

数据仓库的检索和存储优化策略

本文针对数据仓库的检索和存储优化展开讨论,提出了一种能够有效提高OLAP(联机分析处理)的策略.文中将数据量大的表进行拆分重组,将其中的各个索引建立为独立的索引表.这样,原来的一个大表就分割成由几个索引表和剩余信息组成的表的集合.这些索引表反映了大表不同维的信息,可以单独使用.当根据索引检索时不用扫描表中的所有信息,而只需扫描索引表即能找到.利用索引表进行检索有效的减少了检索范围,从而提高了检索效率.将该方法应用于实际系统中,取得了显著效果,具有很强的实际意义.     

一种存储复杂多边形包含关系的四叉树索引

地表覆盖/土地利用矢量数据中存在大量包含成千上万个空洞(甚至嵌套空洞)的复杂多边形,现有空间数据索引没有表达复杂多边形及其空洞之间的包含关系,导致空间数据冲突检测与更新等处理存在计算量大、效率低等问题.针对此问题,提出了一种存储多边形包含关系的四叉树索引方法.该方法根据结点中的多边形与四叉树相应象限中轴线相交的方式将多边形对象分为5种类型,即仅与X正轴相交、仅与X负轴相交、仅与Y正轴相交、仅与Y负轴相交以及与XY轴都相交,并将这些多边形对象分别存储在相应层次索引结点中的5个子列表(桶)中,然后在结点多边形对象中存储多边形之间的父子包含关系.最后设计并实现了该索引及相应的查询、插入、删除等算法,并用实际地表覆盖数据验证了本文方法的有效性.实验结果表明,采用本文索引方法的复杂地表覆盖矢量数据增量更新效率数倍于现有四叉树索引方法,且随着数据量的增加效率提高更明显.     

一种高效的实视图选择算法

数据往往被存储在分布式的数据源中,当需要对数据做查询操作时,就无法像查询单数据源那样有效率.联机分析处理(OLAP)被提出,并用来克服这个问题.在这个过程中,为了提高OLAP的查询效率,采用了将视图实体化的技术,即将综合性的复杂的查询结果放入实视图中,再将OLAP查询与实视图相互关联起来.但是,实视图需要占据大量的物理存储空间,而当数据源一旦更新时,为了与底层数据源保持一致,必须对实视图进行相应的更新维护,从而产生实视图的维护代价,因此实视图选择必须在提高查询响应速度和资源限制二者之间做出一定的权衡.文章提出了一种算法,可以在对维护代价一定条件约束下,使得查询代价达到最小的算法.经过实验,该算法不仅计算复杂度较小,而且维护成本较低.     

OLAP聚集计算中的维存储技术

为解决传统行存储结构导致OLAP聚集计算效率低下的问题,设计了基于维存储的OLAP数据存取技术.首先,将OLAP事实表中的维属性集和度量属性集定义为2个列族,每张维表的所有属性定义为1个列族.对维表进行二进制编码,生成维层次编码,从而保持了维的层次语义特性.以(维层次编码,度量值)对形式按列组织数据,消除查询时维表与事实表的复杂连接操作运算.然后,采用自底向上方法构建B+树,对维层次编码进行索引,加快了数据读取效率.通过增删事实表和维层次编码-度量表中相应的列,实现维和度量的增加和删除.性能分析结果表明,这种OLAP数据存取技术具有良好的可扩展性,能高效地管理和存取OLAP海量多维数据,有效支持上层OLAP聚集计算.     

QGrid:一种空间移动对象并行索引结构

为提高空间移动对象数据更新效率和查询准确率,提出了一种空间移动对象并行索引结构.利用主索引和辅助索引支持对空间对象进行基于范围的查询和基于对象标识的查询,还通过查询索引将更新操作和可能受其影响的查询操作相连接,在满足并行操作时间片语义的同时,避免了传统方法进行范围查询时对查询范围内相关对象及相关索引结构全部进行锁定的需求.实验结果表明:高负载环境下,该索引结构不但能保证查询准确率,其处理能力也明显优于传统索引结构.该索引通过提高系统并行度,使同一范围内的更新和查询操作可以并行执行,提升了系统整体运行效率.     

林业资源数据集群的快速索引设计

设计一种快速索引以管理分布存储的林业资源数据, 通过大量独立数据节点共同负载数据请求, 减少数据访问过程的互斥, 实现了空间与属性数据的分布式存储并行访问. 实验结果表明, 基于目前的应用服务器集群, 应用该快速索引方法, 能以较低的改进成本提高整个数据集群的快速统计和更新能力.     

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.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

Jane Eyre——A Feminist In The 19th Century

In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.     

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-