基于用户兴趣反馈的智能合作过滤模型的研究

随着网络信息资源的迅速增加,如何及时准确地获取所需信息是现代网络信息过滤技术需要解决的主要问题.为了给用户提供更准确的信息,提出了一种基于用户反馈的智能合作过滤模型(Agent collaborative filtering model based on users'feedback,ACFM)和用户兴趣模型,该模型通过隐式反馈和显式反馈这两种用户兴趣反馈学习实现合作过滤.实验结果表明,ACFM在预测用户兴趣的效果和推荐搜索信息的准确率方面比传统的搜索引擎有明显改善.     

基于Agent的个性化信息过滤系统的设计与实现

针对用户个性化服务的特定需求，文中提出了一种基于Agent的个性化信息过滤系统的设计思想及其实现过程。采用基于主题的过滤和基于兴趣的过滤相结合的过滤方法对信息分两次过滤，同时利用Agent跟踪用户的浏览行为，从而提供隐式反馈。系统能够根据文本的内容自动判别文本所属主题分类，并计算待过滤信息与用户兴趣之间的相关度，最后利用用户的反馈对用户兴趣模型进行更新，从而帮助用户准确获取有用信息。     

基于Agent的个性化信息过滤系统的设计与实现

针对用户个性化服务的特定需求,文中提出了一种基于Agent的个性化信息过滤系统的设计思想及其实现过程。采用基于主题的过滤和基于兴趣的过滤相结合的过滤方法对信息分两次过滤,同时利用Agent跟踪用户的浏览行为,从而提供隐式反馈。系统能够根据文本的内容自动判别文本所属主题分类,并计算待过滤信息与用户兴趣之间的相关度,最后利用用户的反馈对用户兴趣模型进行更新,从而帮助用户准确获取有用信息。     

基于本体论的信息过滤模型

信息过滤已成为当今信息技术研究的热点。主要介绍布尔模型、向量空间模型和概率模型,并分析它们各自的优点及存在的不足之处。在此基础上,提出一种新的信息过滤模型——基于本体论的信息过滤模型,阐述用户兴趣模板的构建步骤、用户相关反馈和更新算法,为基于本体的信息过滤技术提供了理论基础。     

基于混合学习策略的多Agent信息过滤系统

针对用户个性化服务的要求,给出了一种基于混合学习策略和BP神经网络的多Agent信息过滤系统实现方案。系统采用蒙特卡罗强化学习算法进行多Agent协作学习,同时运用三层BP神经网络计算用户的满意度,根据算出的满意度对用户兴趣模型进行更新。本系统中用户无须反复提供显示反馈,由Agent跟踪并记录用户的浏览行为而得到用户的隐式反馈信息,从而减轻了用户的负担。     

个性化网络信息过滤Agent的反馈评价机制

文章描述了信息过滤的作用,并介绍了一个基于Agent的万维网文档信息过滤系统。文中提出了个性化网络信息过滤Agent的结构及其实现方案,并讨论了用相关反馈评价机制更新用户兴趣模型的问题,建议用决策树从用户分类的文档集中学习用户的信息兴趣。     

基于隐式反馈的个性化信息过滤方法

如何为用户提供更为满意的、符合其个性化的信息过滤,已成为一个重要的研究课题。针对这一情况,本文提出了一个基于隐式反馈的个性化信息过滤的设计思路和实现方法即通过观察用户与系统交互的动作学习用户的兴趣,根据用户兴趣帮助用户过滤掉那些他不感兴趣的信息。并对其涉及的关键技术用户兴趣建模,文档的表示和信息的过滤等方面进行了详细描述,并对当前存在的问题进行了探讨。     

基于退火遗传算法的网络信息过滤系统研究

分析了网络信息过滤一般模型以及现有技术,研究了如何更准确地构建用户模板,提出了一种基于遗传算法的网络信息过滤系统模型,并且引入了遗传扩展操作和Boltzmann群体更新准则来改进遗传算法存在的缺点,同时给出了一种Roocchio反馈模型对用户兴趣模板进行更新和维护.实验结果表明,基于该模型设计的网络信息过滤系统能够有效实现对网络信息过滤.     

WMS:面向领域的Web信息挖掘系统

研究并实现了一个面向领域的Web挖掘系统WMS，能有效地帮助用户挖掘Web上的信息和知识，用户可以通过提交Web页面、文本文档、URLs或关键词，向系统表达自己希望获得的信息主题，系统自动学习用户对特定领域的兴趣．并依据用户对系统采集文档的反馈评估，不断自适应地调整用户兴趣模型．WMS依据用户兴趣模型，利用智能Agents，对用户感兴趣的有关信息进行搜索和过滤，并对主要相关Web站点的信息更新进行监测，利用人工神经网络和智能Agents技术，WMS对所积累的文档库进行信息和知识挖掘，并自动将新信息推荐给用户．     

基于贝叶斯后验概率和非合作博弈的推荐算法

针对传统协同过滤推荐算法推荐精度较低等问题,提出一种基于贝叶斯后验概率预测和非合作博弈的个性化推荐算法。采用文件主题模型求取用户与其参加过的所有社交活动的主题分布,利用隐含主题概率分布表征用户兴趣度,根据信任传递机制求取用户的直接信任和间接信任,形成用户间的信任度;将用户的兴趣度和信任度等隐式特征赋予合理的先验分布,利用贝叶斯后验概率预测隐式特征后的显式反馈;依据显式反馈将推荐结果转化为非合作博弈中用户效益最大化的纳什均衡求解。仿真对比实验表明,与其他三种推荐算法相比该算法的查准率至少提高了3.13%,查全率至少提高了2.62%。     

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).