商空间理论在产量预测中的应用

商空间理论是研究不同粒度世界的一种新的数学工具。它用三元组（X,f,T） 描述一个问题,其中X 表示问题的论域,f（．） 是论域属性,Ｔ 是论域的结构。通过分析求解问题（X,f,T） ,对论域Ｘ 及其有关的结构、属性进行深入分析和研究,从而完成不同粒度世界的描述,并有着完整的理论基础。该文主要描述了商空间粒度的构建和计算并应用于农作物产量的预测,通过实验取得了很好的确定结果。     

商空间粒度计算理论在数据库和数据仓库中应用

商空间理论是研究不同粒度世界的一种新的数学工具。它用三元组(X,f,Т)描述一个问题,其中X表示问题的论域,f(·)是论域属性,Т是论域的结构。通过分析求解问题(X,f,Т),对论域X及其有关的结构、属性进行深入分析和研究,从而完成不同粒度世界的描述,并有着完整的理论基础。该文首次将商空间粒度理论应用于对数据仓库中数据进行了粒度分析,取得了很好的确定结果。     

作物产量预测的粒度分析法

针对作物产量预测,提出基于商空间粒度计算的分析法。在商空间粒度计算理论思想下,分析作物产量序列中粒度的选取,用属性划分方法对论域X进行颗粒化,对属性f取不同的粒度进行颗粒化。通过属性的粒度变化对论域进行划分,得到新的商空间并应用其解决问题,可以降低问题复杂度。通过商空间理论中的分层与合成技术选取大小合适的粒度,能全面获取产量序列中的信息,也更加符合人类智能特点。冬小麦产量预测实验结果也证明这种粒度分析和选取方法是有效的。     

粒度计算模型的研究

粒度计算可以看作是利用粒度解决问题的理论、方法、技术和工具。文中介绍粒度计算的一些基本概念以及研究粒度计算的目的，阐述粒度计算研究的基本问题，分析当前粒度计算研究的几个模型，重点讨论不同粒度世界的描述法——商空间法，并从各种角度对几个模型做出比较，得出它们的联系与区别，证明几种方法各有优劣。     

商空间理论与粗糙集的比较

文中以比较的方式讨论了粗糙集理论和商空间理论之间的关系,通过对两理论基本算法及复杂度和理论扩展的分析,得出商空间理论与目前流行的"粗糙集"理论的共同之处在于:都是利用等价类来描述"粒度",都是用"粒度"来描述概念。但两者讨论的着重点有所不同,商空间理论的着重点是研究不同粒度世界之间的互相转换、互相依存的关系,是描述空间关系学说的理论;而目前的粒度计算(如粗糙集理论等)主要是研究粒度的表示、刻画和粒度与概念之间的依存关系。更主要的不同在于:商空间理论是在论域元素之间存在有拓扑关系的情况下进行研究的,即论域是一个拓扑空间,而现在的粗糙集理论其论域只是简单的点集,元素之间没有拓扑关系,因此商空间理论不仅可用于数据挖掘、知识发现等方面的应用,而且对路程规划、空间状态分布等约束问题同样适用。     

商空间理论与粗糙集的比较

文中以比较的方式讨论了粗糙集理论和商空间理论之间的关系,通过对两理论基本算法及复杂度和理论扩展的分析,得出商空间理论与目前流行的"粗糙集"理论的共同之处在于:都是利用等价类来描述"粒度",都是用"粒度"来描述概念.但两者讨论的着重点有所不同,商空间理论的着重点是研究不同粒度世界之间的互相转换、互相依存的关系,是描述空间关系学说的理论;而目前的粒度计算(如粗糙集理论等)主要是研究粒度的表示、刻画和粒度与概念之间的依存关系.更主要的不同在于:商空间理论是在论域元素之间存在有拓扑关系的情况下进行研究的,即论域是一个拓扑空间,而现在的粗糙集理论其论域只是简单的点集,元素之间没有拓扑关系,因此商空间理论不仅可用于数据挖掘、知识发现等方面的应用,而且对路程规划、空间状态分布等约束问题同样适用.     

粒度计算模型的研究

粒度计算可以看作是利用粒度解决问题的理论、方法、技术和工具。文中介绍粒度计算的一些基本概念以及研究粒度计算的目的,阐述粒度计算研究的基本问题,分析当前粒度计算研究的几个模型,重点讨论不同粒度世界的描述法———商空间法,并从各种角度对几个模型做出比较,得出它们的联系与区别,证明几种方法各有优劣。     

基于粒度计算的覆盖算法

为了更好地解决高维海量数据的分类问题,本文提出一种基于粒度计算的覆盖算法.该算法以粒度计算为理论依据,指出在分析研究某一问题时,可以适当将其属性、论域或者结构粗化,求得某个商空间,在该商空间中抓住事物的本质对其研究,对某些在同一个粗粒度世界无法识别或者彼此特征区别很弱的对象可以换一个粒度世界对其分析,从而全面了解整个问题;以构造性学习算法--覆盖算法为具体实现工具,得到多个商空间中的结果,最终由商空间理论中的函数合成法获得完整结果.实验证明这种基于粒度计算的覆盖算法在解决分类问题时是行之有效的.     

图像分割的商空间粒度原理

从商空间粒度理论角度分析图像分割概念,研究已有的图像分割方法,提出图像分割的商空间粒度原理．用商空间的三元组（X,f,Г）-（[X],[f],[Г]）来描述图像分割过程,阐述基于商空间粒度计算理论的图像分割原理及基于粒度分层、合成及其综合技术下图像分割的方法,并提出了基于粒度合成原理的复杂纹理图像的分割算法．该算法通过分别提取多纹理图像中纹理区域的方向性及粗细度特征,形成图像的不同粒度,然后根据粒度合成原则,对所形成的粒度进行合成,从而实现对纹理图像的分割,实验表明该算法对复杂纹理图像分割是有效的．     

基于粒计算的多粒度数据分析方法综述

多粒度数据是一种特殊的、有用的数据类型,它通过对论域(研究对象的集合)采用不同的粒化方式使得数据能够在多个粒度空间中进行呈现,在此基础上可以开展数据的多层次知识发现研究.商空间理论、序贯三支决策、多粒度粗糙集、多尺度数据分析模型和多粒度形式概念分析是几种常见的、有效的多粒度数据分析方法,已受到人们的广泛关注.本文对基于...     

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).