基于Mapreduce的Apriori改进算法

由于传统的Apriori算法是串行的并且效率较低,分析了Apriori算法的计算过程,针对其原理设计了一种基于Mapreduce的并行Apriori改进算法.实验结果证明,改进的算法能较好地提高关联规则挖掘的效率,具有接近线性的加速比和良好的应用价值.     

基于改进Apriori算法的配电网设备退役信息挖掘

影响配电网设备提前退役的因素复杂多样,而且多种因素之间互相作用。为了筛选出影响设备提前退役的主要因素候选集,可以利用数据挖掘算法得到其中关联规则。其中,Apriori算法是最经典的挖掘关联规则的算法。但是传统的Apriori算法时间复杂度过大,计算效率不高。针对这一现状,提出一种基于三维矩阵的Apriori优化算法,通过建立三维矩阵以及简约数据库的方式,减少了传统算法中的计算冗余,挖掘出影响配电网设备提前退役的因素频繁项集。结果表明:改进算法能够得到配电网设备退役因素的关联规则并明显提高计算效率。     

基于Spark的Apriori并行算法优化实现

针对传统Apriori算法处理速度和计算资源的瓶颈,以及Hadoop平台上Map-Reduce计算框架不能处理节点失效、不能友好支持迭代计算以及不能基于内存计算等问题,提出了Spark下并行关联规则优化算法.该算法只需两次扫描事务数据库,并充分利用Spark内存计算的RDD存储项集.与传统Apriori算法相比,该算法扫描事务数据库的次数大大降低;与Hadoop下Apriori算法相比,该算法不仅简化计算,支持迭代,而且通过在内存中缓存中间结果减少I/O花销.实验结果表明,该算法可以提高关联规则算法在大数据规模下的挖掘效率.     

基于MapReduce的Apriori前后项约束关联规则改进算法

针对经典的Apriori算法依赖内存,只适用于小规模数据集,在面对海量数据集时显得无能为力以及该算法没有考虑用户的需求情况等问题,提出了基于MapReduce的Apriori前后项约束关联规则改进算法。该方法首先对经典Apriori算法挖掘过程进行了改进,加入了用户的前后项约束规则,使得在挖掘过程中剪枝的程度更大并且获取到更加精准的规则。然后利用云计算的MapReduce编程技术,对改进的Apriori算法的各个步骤并行化。实验结果表明,改进的算法在处理不同的数据集时有一定的优势,然后经过MapReduce模型并行化后,提高了对海量数据的处理能力和效率,并且具有良好的扩展性。     

关联规则挖掘的Apriori算法综述

关联规则挖掘是数据挖掘研究领域中的一个重要任务,旨在挖掘事务数据库中有意义的关联。随着大量数据不停的收集和存储,从数据库中挖掘关联规则显得越来越有必要性,关联规则挖掘的Apriori算法是数据库挖掘的最经典算法并得到广泛应用,在介绍关联规则挖掘和Apriori算法的基础上,发现Apriori算法存在着产生候选项目集效率低和频繁扫描数据等缺点。综述了Apriori算法的主要优化方法,并指出了Apriori算法在实际中的应用领域,提出了未来Apriori算法的研究方向和应用发展趋势。     

基于向量矩阵的Apriori改进算法研究

针对传统的关联分析算法Apriori执行效率低、I/O过重、计算量过大等问题,提出了一种通过减少扫描数据库次数来降低候选项集计算复杂度, 在频繁项集求解过程中通过将事务项集转换为行向量,利用“与”操作来提高算法执行效率的Apriori改进算法。利用学生在校行为数据集对Apriori改进算法进行有效性和高效性验证。同时,为了符合算法对样本数据的要求,在样本数据处理过程中对原始数据进行了清洗和离散化处理,定义了分析对象的样本数据离散化处理的规则。通过实验分析比较了Apriori改进算法与经典Apriori算法的性能。结果表明,Apriori改进算法保持了对实际分析对象关联规则挖掘的有效性,同时具有更高的执行效率。     

基于矩阵的频繁项集发现算法

Apriori算法是关联规则的经典算法.在分析经典Apriori算法的基础上,提出了一种有效的基于矩阵的Apriori的改进算法.该算法应用了矩阵的思想,只需对数据库扫描一次,即可得到频繁项集,大大提高了算法的效率.     

数据挖掘中的剔除非频繁项超集法

在关联规则数据挖掘中，根据非频繁项的超集仍是非频繁项的结论，总结出一种高效的关联规则算法：剔除非频繁项超集法，并与经典的Apriori算法作比较，其效率比Apriori算法高。     

数据挖掘中频繁项集挖掘算法的改进

Apriori算法是关联规则挖掘中的经典算法,一直是数据挖掘领域的研究热点。传统的Apriori算法由于产生过多的无用的候选项集以及需要多次扫描数据库导致在一定程度上限制了算法的效率。本文针对这一问题,提出一种新的RF－Apriori算法。该算法首先对数据进行二元处理;然后利用项集的反单调性减少候选项集的产生,从而提高算法效率。实验结果表明,RF －Apriori算法效率明显优于Apriori算法。     

基于Apriori算法的多维关联规则挖掘研究

关联规则是数据挖掘中的一个重要研究方向.经典的Apriori算法是一种最有影响的挖掘布尔型关联规则频繁项集的算法,但其并不适合挖掘近年来兴起的多维数据模型.在改进Apriori算法的基础上,提出了一种"二次剪枝"的算法,此算法适用于挖掘多维关联规则,并且在一定程度上提高了算法效率.     

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     

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     

Journal of Donghua University ( English Edition) Contents of Volume 31

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