基于C2架构的EJB构件组装

在基于构件软件工程（CBSE）开发方法中,构件使用者利用现有构件集成应用系统,因此,如何组装构件一直是人们研究的热点。在分析C2构架和EJB构件标准的基础上,提出了基于C2架构进行EJB构件组装的方法和步骤,并通过实例分析了这种方法的合理性和可重用性。     

一种基于CBSE的嵌入式实时软件建模方法研究

基于构件的软件工程（CBSE）是众多嵌入式软件开发方法中的一种崭新方法。本文提出一种RT—UML^＊／LTLC的双语言框架来对基于CBSE的嵌入式实时软件的建模．既能充分地刻画出嵌入式软件实时．资源严格有限等特点,又能较好地体现出构件的特征,能更容易地过渡到基于构件的嵌入式软件开发方法的后继阶段。     

基于xml技术的软件构件表示与检索

软件构件库作为构件复用的基础物质仓库,扮演了极为重要的角色,而可复用构件的表示、分类、检索是构件库的关键.本文在构件库系统的构件分类与描述方案的选择设计中,分析了构件的刻面分类方法,提出采用XML技术实现构件的刻面描述方案,并从技术实现、发展演化等方面对该方案作了较详细的分析,之后参照国内外相关学术成果,结合XML技术特点,给出了具体的刻面设计及描述实现,从而建立起软件构件库系统的构件数据模型.     

基于相似性分析的软件构件聚类研究

设计了一种对基于XML描述的软件构件进行聚类的算法（即基于模拟退火的构件聚类算法）,该算法通过模拟金属退火基本原理对构件库中的软件构件聚类进行全局优化.构件聚类时,根据一般意义的树间编辑距离,提出一种用于判断基于XML描述的构件间是否相似的度量测度（称为XML编辑距离）.利用XML编辑距离,可将构件间相似性度量的时间复杂度限制在多项式级,且能保持构件的XML描述文档的节点语义信息和节点间的祖孙嵌套关系.最后,在构件库测试模型上进行实验,结果证实了基于模拟退火的构件聚类算法在构件查询实践中的可行性和有效性.     

以构件为核心的软件工业化的生产方式

从CBSE的工作角度出发,提供了两个软件工业化的生产方式由构件形成的应用框架(软件体系结构)的可复用生产方式;另一种是面向需求的领域架构/构件生产方式.以异构构件组装模型为例,提出了构件柔性的敏捷式定制生产方式,该模型适应性强,柔性强,可以针对不同的管理模式与流程,实现功能的可裁剪性、系统的可配置性、流程的可重构性.在软件复用的思路下,提高了软件的开发效率和软件质量,实现了开发的快速响应.通过复用构件的开发技术,延长了软件的寿命.通过解决构件可置换关键技术的研究,提高了系统的性能,可靠性和互操作性,减少了开发代价和维护代价.     

基于接口矩阵分析的构件变化检测方法的研究*

针对构件的变化性问题一直都是基于构件的软件工程（CBSE）中的一个关键问题,首先对构件模型以及构件匹配原则进行形式化描述,构造了构件的接口关系矩阵;然后根据构件匹配原则,对构件接口关系矩阵进行分析,动态地检测构件的变化,判断构件变化可能会对其他相关构件以及整个系统产生影响;最后实现了构件变化分析的辅助工具CIDT（component interface detecting tool）,并在软件开发以及维护过程中使用CIDT对系统进行动态的检测和分析。     

CBSE跨越七道槛

基于构件的软件工程(Compwnent- Based Software Engineering.简称CBSE) 或基于构件的开发(Component-Based Development,简称CBD)是一种软件开发的新范型,它是使用与特定构件模型相关的合成技术,复用构件库中可信赖的构件,高效率、高质量地构造应用软件系统的工程化过程。CBSE遵循“购买而不创建”的开发哲学,让人们从“一切从头开始”的程序编制转向软件组装。基于构件的开发任务包括创建、检索和评价、适配、组装、测试和验证、配置和部署、维护和演进,以及遗留系统的再工程等主要活动,它们与传统的生命周期中的方法不尽相同,开发过程分为以开发领域构架和构件为目标的领域工程过程,以开发     

TinyOS集成开发环境的设计与实现

TinyOS是针对资源非常有限的无线传感器网络节点而设计的构件化操作系统,采用构件化描述语言nesC进行开发。由于采用基于构件的软件工程（CBSE）技术,TinyOS可以看成是一个构件库,简化了无线传感器节点上的应用程序设计,但目前缺乏系统配套的构件管理工具和高效集成开发环境(IDE)。分析了构件化描述语言nesC和TinyOS的开发过程,设计并实现了一种构件化集成开发环境及其构件管理器。根据分析和实际使用,该开发环境能有效地简化开发流程并提高开发效率。     

基于体系结构的构件开发技术研究与应用

基于构件的软件工程（CBSE）开发方法一直是计算机人员研究的热点.本文在分析Petri网模型和C2构架的基础上,使用Petri网模型分析软件开发过程,研究基于C2架构的构件组装的方法和步骤,并通过实例分析了这种方法的合理性.     

基于XML的构件库管理框架的研究与实现

随着基于构件的开发方法(CBD)的普遍应用,作为CBD的核心技术的可复用构件库的管理已成为学术界和业界共同关注和研究的热点。论文在对构件库和XML进行深入研究的基础上提出并初步实现了一个基于XML的构件库管理框架,并对作为其关键技术的基于XML的构件描述与检索做了详细的论述。     

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).