基于包含度和频繁模式的文本特征选择方法

大数据时代,文本数据量的爆炸式增长使得特征选择成为文本挖掘领域最关键的任务之一。文档中的词语和模式规模庞杂,故需保证所挖掘特征的质量充满挑战。“基于模式”特征选择方法具有传统“基于词语”方法所没有的优越特性,可以进行有效地信息去噪,提升文本挖掘性能。该文提出基于包含度和频繁模式的文本特征选择方法: 首先,定义基于包含度的相似性度量原理;然后,提出基于包含度的冗余文本频繁模式过滤方法。基于包含度度量文本频繁模式间相似性,以此去除子模式及相似度较高的交叉模式。再通过冗余模式去噪,提升文本频繁模式挖掘性能;提出基于关联度的文本特征选择方法。以经过过滤处理后的非冗余文本频繁模式为基础,进行文本特征选择,并利用词语与文档的关联度进行词语类别划分及权重分配。使所选特征与文档关联度更加清晰,分类效果更好。通过在数据集Reuters-21578上的实验得知,基于包含度和频繁模式的文本特征选择算法性能,优于当前普遍应用的传统文本特征选择方法和新的特征选择及特征抽取方法。     

半监督特征选择综述

如何针对半监督数据集,利用不完整的监督信息完成特征选择,已经成为模式识别与机器学习领域的研究热点。为方便研究者系统地了解半监督特征选择领域的研究现状和发展趋势,对半监督特征选择方法进行综述。首先探讨了半监督特征选择方法的分类,将其按理论基础的不同分为基于图的方法、基于伪标签的方法、基于支持向量机的方法以及其他方法;然后详细介绍并比较了各个类别的典型方法;之后整理了半监督特征选择的热点应用;最后展望了半监督特征选择方法未来的研究方向。     

文本分类中一种混合型特征降维方法

提出一种基于特征选择和特征抽取的混合型文本特征降维方法,分析基于选择和抽取的特征降维方法各自的特点,借助特征项的类别分布差异信息对特征集进行初步选择。使用一种新的基于PCA的特征抽取方法对剩余特征集进行二次抽取,在最大限度减少信息损失的前提下实现了文本特征的有效降维。对文本的分类实验结果表明,该特征降维方法具有良好的分类效果。     

基于神经网络的中文文本分类中的特征选择技术

基于神经网络的中文文本分类需要解决的核心问题是特征的选择问题,特征选择涉及选择哪些特征和选择的特征维度两个问题。针对上述问题,提出了信息增益(IG)与主成分分析(PCA)相结合的特征选择方法。通过实验比较分析了不同特征选择方法与特征维度对分类性能的影响,证明了该特征选择方法在基于神经网络的中文文本分类中的优越性,并得出神经网络的特征输入维度在200左右的时候分类性能最佳。     

基于二次Renyi熵的正则化互信息特征选择方法

提出了一种基于二次Renyi's熵的正则化互信息特征选择方法,该方法能高效地对互信息进行估计从而使计算复杂度大大降低。同时把正则化互信息特征选择方法与嵌入式方法相结合得到一个两段式特征选择算法,该算法可以找出更具特征的特征子集。通过实验比较了该方法与其他基于互信息的特征选择算法的效率与分类精度,结果表明该方法能够有效改善计算复杂度。     

基于特征选择融合的垃圾邮件过滤方法

针对传统垃圾邮件过滤问题中采用单一特征选择方法不能够有效提取训练集中全部重要特征或提取结果存在特征冗余的问题,提出一种基于多种特征选择方法融合的垃圾邮件过滤模型SF_FSF(Spam filtering based on feature selection fusion)。SF_FSF方法通过引入信息融合的概念,将特征选择看成一个决策问题,采用基于平均投票法的信息融合模型进行特征选择结果的融合,以提取垃圾邮件数据集中的重要特征,获得优秀的过滤能力。实验结果表明,SF_FSF方法比基于单一特征选择的垃圾邮件过滤方法得到了更好的过滤结果。     

一种适合大规模数据集的特征选择方法

研究训练样本重要特征选择问题,提出了一种适合大规模数据集的特征选择方法。在不同的样本空间中利用特征相似性和浮动搜索方法的思想选择特征,基于互信息和分类准确度加权选择分类器,提出了基于Bagging选择性组合算法来提高特征选择算法稳定性。采用KDD Cup’99中的入侵检测数据对算法性能进行了验证。     

粗糙集的特征选择在客户关系管理中的应用

介绍了粗糙集理论的特征选择在客户关系管理中的应用.分析了以前特征选择方法中由于特征数目过多而造成分类时间和精度不高的缺点,提出了一种基于粗糙集的特征选择方法,其特点是以特征在分类中的重要性对特征进行选择.对客户关系管理进行了研究,为解决客户关系管理问题提出了一个新的方法,基于粗糙集的特征选择方法与传统的特征选择方法相比也能达到降维的目的.最后实验结果表明该算法是可行的.     

结合粗糙集和禁忌搜索的网络流量特征选择

针对网络流量特征属性的优化选择问题,提出了一种结合粗糙集和禁忌搜索的网络流量特征选择方法(RS-TS).该方法通过粗糙集算法对网络流量特征属性进行约简,将所得到的特征子集作为禁忌搜索的初始解,并利用禁忌搜索得到最优特征子集.实验验证RS-TS方法优于基于GA的特征选择方法和基于IG的特征选择方法,能够有效地去除网络流量的冗余特征属性,提高网络流量分类精度.     

基于加权正域的特征选择算法

基于邻域粗糙集的特征选择算法无法评价特征与样本之间的相互关系,为此,通过融合基于大间隔获得样本对特征的评价准则,提出了基于加权正域的特征选择算法。该算法有效地实现了特征对样本的区分能力与样本对特征的贡献程度的综合利用。在UCI数据集和5个高维小样本数据集上的实验结果表明,相比传统的单准则评价的特征选择方法,该方法不仅能有效地提高特征选择的分类性能,而且更加有利于处理高维小样本数据集。     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.