一种基于序列末项位置信息的序列模式挖掘算法

针对PrefixSpan算法中反复扫描投影数据库寻找局部频繁项并重复构造挖掘大量重复投影数据库的不足,提出一种基于序列末项位置信息的序列模式挖掘算法SPM-LIPT。通过连接2-序列位置信息表(LIPT)找到序列模式的下一项,实现序列模式增长,避免对投影数据库反复扫描;同时通过检查相同末项序列首位置信息表(SLIFPT)进行前向剪枝;消除大量重复投影的构建。最后通过实验证明了算法的有效性。     

基于二级索引结构无候选项闭合序列模式挖掘算法

针对CloSpan算法分两个阶段挖掘闭合序列模式中第一阶段需要保持候选序列且未充分利用项的位置信息、存在对数据库重复扫描和计算大小的不足,提出了posCloSpan算法。算法通过对二级索引结构进行检索实现向前剪枝,避免数据库重复扫描以及对超序索引表、子序索引表的检测,实现非闭合序列的修剪,无须保存候选序列。实验结果证明,算法在处理较长序列以及存在大量重复投影数据库的数据源时,有效降低了时间上的开销。     

改进的FLWAP的Web访问序列模式挖掘方法

为了提高序列模式挖掘的FLWAP-mine算法挖掘海量数据的效率和性能,基于减少数据库访问次数原则和序列模式的Apriori性质对FLWAP-mine算法进行改进,构造FLWAP-tree过程中只扫描一次访问序列数据库,对树进行剪枝删除非频繁事件。模式挖掘过程中采取投影数据库思想,只搜索当前模式的投影树,对构造的投影树判断剪枝,去除非频繁事件,进一步缩小搜索范围。实验表明,当数据量较大或支持度阈值较小时,改进的FLWAP-mine算法比FLWAP-mine算法有更好的性能。     

基于位置信息的序列模式挖掘算法*

PrefixSpan算法在产生频繁序列模式时会产生大量的投影数据库,其中很多投影数据库是相同的。提出了基于位置信息的序列模式挖掘算法——PVS,该方法通过记录每个已产生投影数据库的位置信息,避免了重复产生相同的投影数据库,从而提高了算法的运行效率。通过实验证明,该算法在处理相似度很高的序列数据时比PrefixSpan算法有效。     

基于Apriori的快速剪枝和连接的新算法

挖掘关联规则是目前数据挖掘领域热点研究话题之一。它的目的在于在数据库中挖掘有趣的关联规则。在关联规则分析及Apriori算法分析上,针对Apriori算法的瓶颈问题,许多有效的改进算法被提出。文中提出了QPCA算法。该算法利用矩阵分析的方法,仅需要扫描数据库一次,同时此算法优化了连接和剪枝操作,通过快速的剪枝和连接可以很快地获取最少的候选项集,避免了频繁项集之间的重复判断连接,因此大大提高了算法的效率。实验结果表明,该算法在挖掘时间上有很大提高。     

一种基于位置信息的高效DNA序列挖掘算法

类Apriori算法在产生频繁模式时需要多次扫描数据库,并且产生大量的候选集;Free Span和Prefix Span等基于投影数据库的算法在产生频繁模式时会产生大量的投影数据库,占用很多内存空间,这些都造成了很大的冗余。针对以往序列挖掘算法存在的不足,提出一种高效的序列挖掘算法——基于位置信息的序列挖掘算法PBSMA(Position-Based Sequence Mining Algorithm)。PBSMA算法通过记录频繁子序列的位置信息来减少对数据库的扫描,利用位置信息逐渐扩大频繁模式的长度,并且借鉴关联矩阵的思想和Prefix Span算法中前缀的概念,深度优先去寻找更长的关键模式。实验结果证明,无论在时间还是空间上,PBSMA算法都比Prefix Span算法更高效。     

基于数据库划分的关联规则算法

关联规则是数据挖掘的一个重要研究方向.分析了FP算法的优缺点,提出了一种基于数据库划分的算法PFp算法,从理论上证明了该算法的正确性.该方法将事务数据库划分为子事务数据库,在子事务数据库中挖掘局部频繁项集,并入到全局频繁项集中,采用连接和剪枝策略有效挖掘出局部不频繁但全局频繁的频繁项集.实验结果表明,该算法比FP算法更加有效.     

无重复投影数据库扫描的序列模式挖掘算法

序列模式挖掘在Web点击流分析、自然灾害预测、DNA和蛋白质序列模式发现等领域有着广泛应用.基于频繁模式增长的PrefixSpan是目前性能最好的序列模式挖掘算法之一.然而在密数据集和长序列模式挖掘过程中会出现大量的重复投影数据库,使得这类算法性能下降.算法SPMDS通过对投影数据库的伪投影做单项杂凑函数,如MD5等,检查是否存在重复的投影数据库,避免大量重复数据库的扫描,并采用一些必要条件简化投影数据库的搜索,进而提高算法的性能.实验和分析都表明SPMDS性能优于PrefixSpan.     

基于PrefixSpan的序列模式挖掘改进算法

针对序列模式挖掘算法PrefixSpan在挖掘过程中需要构造大量投影数据库的不足,提出IPMSP算法,在递归挖掘过程中,通过检查序列数据库关于前缀的前缀,避免对同一频繁前缀模式构造重复投影数据库,同时舍弃对非频繁项的存储并在投影序列数小于最小支持度时停止扫描投影数据库,从而提高PrefixSpan算法的时空性能。实验结果证明,IPMSP算法在时间和空间性能上优于PrefixSpan算法。     

基于序列前缀技术的XML频繁路径挖掘算法

XML文档是半结构化数据,对其进行频繁路径挖掘可以分为两步：XML文档序列化和序列挖掘阶段. 现有的序列化方式将XML文档表示为Xpath路径集合,其中有大量的节点冗余;序列挖掘阶段采用的类Apriori算法需要多次扫描数据库并产生大量的候选集,采用的PrefixSpan算法会产生大量的投影数据库,占用较大的内存. 针对以往XML频繁路径挖掘算法存在的不足,本文提出一种高效的挖掘算法——基于序列前缀技术的XML频繁路径挖掘算法（PXFP,Prefix-based XML Frequent Path Mining Algorithm）. PXFP算法以广度优先方式遍历XML文档树并将每个节点表示为“节点：父节点”的形式,这种序列化的方式减少了节点冗余. 在序列挖掘阶段借鉴PrefixSpan 算法中前缀的概念,但不产生投影数据库,仅得到直接后缀（即前缀的子节点）,通过记录频繁子路径的位置信息逐渐扩大频繁模式的长度,位置信息的引入减少了对数据库的扫描. 实验结果表明,PXFP算法取得了比PrefixSpan算法更高的时间和空间效率.     

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.