基于动态剪枝的关联规则挖掘算法

介绍了目前关联规则挖掘的研究工作 .分两个部分提出了基于动态剪枝的关联规则发现方法 .讨论了如何实施动态剪枝 ,给出了一个基于三元组结构的树式存储结构 ,在此基础上描述了交易数据库中知识发现算法 .并将提出的方法与关联规则挖掘中具有里程碑意义的 Apriori算法进行了对比分析 ,给出了相应的分析结果 ,实验表明该方法能有效地从数据集中发现关联规则     

一种新的动态关联规则及其挖掘算法

在分析原有定义不足的基础上,提出一种新的动态关联规则,其支持度向量和置信度向量与经典定义相吻合,能更好地反映规则随时间变化的动态信息．进一步提出两种新的动态关联规则挖掘算法：ＩＴＳ和ＥＦＰｇｒｏｗｔｈ．其中：两阶段ＩＴＳ算法具有较好的可理解性;基于扩展ＦＰ树的ＥＦＰｇｒｏｗｔｈ算法适宜于高密度海量数据的挖掘．实验结果表明,该算法具有较好的挖掘性能和可扩展性,适用于动态关联规则的有效挖掘．     

基于审计的时态关联规则研究

传统关联规则挖掘很少考虑关联规则的时间适用性.时态关联规则是指带有时态约束的关联规则,每个关联规则都有着其成立的时间区域.结合其他算法的特点,提出了基于Fisher聚类的时态关联规则挖掘算法,它能够动态地发现关联规则以及关联规则有效的时间区域.实验结果证明该算法是合理有效的。     

一种改进的动态遗传Apriori挖掘算法

在经典关联规则算法Apriori的基础上,提出了一种改进的动态遗传Apriori挖掘算法。通过动态遗传Apriori挖掘算法对学生成绩管理数据库中的课程进行分析,找出各课程之间的隐藏关系,得到一些合理、可靠的课程关联规则,从而根据这些规则进行课程的合理设置。实验结果表明,该算法能高效地解决数据挖掘问题。     

基于PC-树的关联规则挖掘方法

关联规则是数据挖掘的一种常用方法,特别是用在货篮分析中,而关联规则的经典算法Apriori及其改进算法的时间复杂度和空间复杂度都比较高,对于数据库更新、用户定义最小支持度等动态数据挖掘的成本太高。针对这种情况,提出了用PC-树寻找频繁项集的算法,实现高效的动态数据挖掘。     

一种新的动态关联规则及其挖掘算法

在分析原有定义不足的基础上,提出一种新的动态关联规则,其支持度向量和置信度向量与经典定义相吻合,能更好地反映规则随时间变化的动态信息．进一步提出两种新的动态关联规则挖掘算法：ＩＴＳ和ＥＦＰ ｇｒｏｗｔｈ．其中：两阶段ＩＴＳ算法具有较好的可理解性;基于扩展ＦＰ 树的ＥＦＰ ｇｒｏｗｔｈ算法适宜于高密度海量数据的挖掘．实验
结果表明,该算法具有较好的挖掘性能和可扩展性,适用于动态关联规则的有效挖掘．

     

基于粗糙集的多维关联规则挖掘方法

海量的数据使得关联规则挖掘非常耗时,而并非所有的规则都是用户感兴趣的,应用传统的挖掘方法会挖掘出许多无关信息。此外,目前大部分算法是针对单维规则的。因此,定义了一种挖掘语言使得用户可以指定感兴趣的项以及关联规则的参数（如支持度,置信度等）,并提出一种基于粗糙集理论的多维关联规则挖掘方法,动态生成频繁集和多维关联规则,减少频繁项集的生成搜索空间。实例分析验证该算法的可行性与有效性。     

基于模拟退火遗传算法的关联规则挖掘

将模拟退火遗传算法加以改进,应用于关联规则挖掘,提出一种新的基于改进的模拟退火遗传算法的关联规则挖掘算法,并在该算法中,采用自适应方式动态选取交叉和变异概率,有效地抑制了早熟收敛现象,实验结果显示该方法能高效地解决关联规则挖掘问题。     

数据库中动态关联规则的挖掘

关联规则能挖掘变量间的相互依赖关系,但是不能反映规则本身的变化规律．为此本文提出了动态关联规则．首先将整个待挖掘数据集按时间划分成若干子集,每个子集挖掘得到的每条规则分别生成一个支持度和一个置信度,这样每条规则在全集上就对应了一个支持度向量和一个置信度向量．通过分析支持度向量和置信度向量,不仅可以发现规则随时间变化的情况,也能够预测规则的发展趋势．本文还提出了两个挖掘动态关联规则的算法,且对他们做了比较．并给出了柱状图和时间序列两种方法分析这两个向量．最后给出了一个挖掘动态关联规则的应用实例。     

一种基于主属性判定的关联规则挖掘约简算法

关联规则挖掘是经典的数据挖掘方法,越来越多的企业都把它看作是必不可少的战略分析工具。当前关联规则挖掘方法得到的规则过多,令用户在运用时难以理解,因此研究关联规则集的约简方法具有应用价值。研究了数据库模式中关键字包含的主属性对基于Apriori算法的关联规则挖掘产生的关联规则的影响,即部分函数依赖会导致关联规则挖掘的数据集中冗余信息的频繁出现,并产生没有实际价值的关联规则,识别并消除这样的规则就能实现规则集的约简。求全部主属性如同求所有候选关键字问题都是NP难题,因此提出了一种基于一个候选关键字进行验证的算法来判定主属性,从而完成基于主属性判定的关联规则挖掘约简算法的设计与实现,并在最后的实验中验证了该算法的有效性。      

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。     

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.     

Editorial: Special issue on recent advances in hybrid control theory and applications

正The demands of a rapidly advancing technology for faster and more accurate controllers have always had a strong influence on the progress of automatic control theory.In recent years control problems have been arising with increasing frequency in widely different areas,which cannot be addressed using conventional control techniques.The principal reason for this is the fact that a highly competitive economy is forcing systems to operate in regimes where     

Information for Authors

正Aim The Journals of Zhejiang University-SCIENCE(A/B/C)areedited by the international board of distinguished Chinese andforeign scientists,and are aimed to present the latest devel-opments and achievements in scientific research in China andoverseas to the world’s scientific circles,especially to stimulateand promote academic exchange between Chinese and for-eign scientists everywhere.     

Enhancing a leaf radiative transfer model to estimate concentrations and in vivo specific absorption coefficients of total carotenoids and chlorophylls a and b from single-needle reflectance and transmittance

The relative concentrations of different pigments within a leaf have significant physiological and spectral consequences. Photosynthesis, light use efficiency, mass and energy exchange, and stress response are dependent on relationships among an ensemble of pigments. This ensemble also determines the visible characteristics of a leaf, which can be measured remotely and used to quantify leaf biochemistry and structure. But current remote sensing approaches are limited in their ability to resolve individual pigments. This paper focuses on the incorporation of three pigments—chlorophyll a, chlorophyll b, and total carotenoids—into the LIBERTY leaf radiative transfer model to better understand relationships between leaf biochemical, biophysical, and spectral properties.Pinus ponderosa and Pinus jeffreyi needles were collected from three sites in the California Sierra Nevada. Hemispheric single-leaf visible reflectance and transmittance and concentrations of chlorophylls a and b and total carotenoids of fresh needles were measured. These data were input to the enhanced LIBERTY model to estimate optical and biochemical properties of pine needles. The enhanced model successfully estimated reflectance (RMSE = 0.0255, BIAS = 0.00477, RMS%E = 16.7%), had variable success estimating transmittance (RMSE = 0.0442, BIAS = 0.0294, RMS%E = 181%), and generated very good estimates of carotenoid concentrations (RMSE = 2.48 µg/cm², BIAS = 0.143 µg/cm², RMS%E = 20.4%), good estimates of chlorophyll a concentrations (RMSE = 10.7 µg/cm², BIAS = − 0.992 µg/cm², RMS%E = 21.1%), and fair estimates of chlorophyll b concentrations (RMSE = 7.49 µg/cm², BIAS = − 2.12 µg/cm², RMS%E = 43.7%). Overall root mean squared errors of reflectance, transmittance, and pigment concentration estimates were lower for the three-pigment model than for the single-pigment model. The algorithm to estimate three in vivo specific absorption coefficients is robust, although estimated values are distorted by inconsistencies in model biophysics. The capacity to invert the model from single-leaf reflectance and transmittance was added to the model so it could be coupled with vegetation canopy models to estimate canopy biochemistry from remotely sensed data.     

Mr. Twinn’s bombes

This article discusses the history and design of the special versions of the bombe key-finding machines used by Britain’s Government Code & Cypher School (GC&CS) during World War II to attack the Enigma traffic of the Abwehr (the German military intelligence service). These special bombes were based on the design of their more numerous counterparts used against the traffic of the German armed services, but differed from them in important ways that highlight the adaptability of the British bombe design, and the power and flexibility of the diagonal board. Also discussed are the changes in the Abwehr indicating system that drove the development of these machines, the ingenious ways in which they were used, and some related developments involving the bombes used by the U.S. Navy’s cryptanalytic unit (OP-20-G).