面向嵌入式系统的优化编译器生成器设计

构造嵌入式系统是一个硬件软件的协同设计问题 .嵌入式软件的有效开发需要相应编译器的支持 .由于嵌入式系统存储空间有限 ,所以编译器生成的机器代码必须非常紧凑 .我们可以使用编译器的生成器来提高编译器的开发效率 .本文给出了一种编译器生成器的设计原理 ,利用该编译器生成器可以迅速生成面向某种指令系统和机器特征 ,并且能够对输出代码进行自动紧凑的编译器     

面向嵌入式系统的优化编译器生成器设计

给出了一种编译器生成器的设计原理,利用编译器生成器可以迅速生成面向某种指令系统和机器特征,并且能够对输出代码进行自动紧凑的编译器。     

用CUP构造编译器的方法

介绍了编译器自动生成器的基本原理,通过设计一个简单的计算器,说明使用CUP(Constructor of Useful Parsers)构造编译器的方法.     

基于JavaCC的SQL编译器的设计与实现

采用扩展的巴科斯范式(EBNF)定义SQL语言的语法规则,提出了一种基于分析器自动生成工具(JavaCC)的SQL语言编译器的设计模型。该模型采用Java语言开发,具有良好的平台无关性;分别从词法、语法和语义分析、信息提取等方面进行编译器的设计与实现。实际运行结果表明:该模型能够快速高效地构建SQL编译器,且具有良好的可扩展性。     

一种XML解析器技术的研究与实现

介绍了XML解析的详细过程,设计并实现了一个特定Schema的XML解析器的自动生成工具。该生成工具以一个XML Schema文件作为输入,输出一个JavaCC词法和语法规格说明文件,然后在JavaCC工具的帮助下,生成一个基于特定XML Schema的XML解析器。实验证明,这个生成解析器能够对XML文档进行解析的同时,验证其有效性。     

可视编译器的设计与实现

通过一个实际的可视编译器开发实例,描述编译器前端的实现方法。这个编译程序除了易于操作的窗口程序外,还包含了标准C语言子集的编译器。这套编译器涵盖了词法分析器、语法分析器、语义分析器、中间代码生成器和简单错误处理器等一整套程序。通过这个实例可以直观地表现词法和语法的构造过程,图文并茂,生动说明编译器中词法器、语法器的功能及其构造过程。     

基于编译支持错误跟踪的测试用例自动化生成方法

测试用例的自动生成是实现测试自动化的重要保障,是验证可信软件的基本方法.在分析现有测试用例自动生成方法的基础上,提出了一种基于编译的错误可跟踪的测试用例自动生成方法.该方法以编译器为依托,通过对其语法和语义进行扩展,将测试需求很好地融入到源程序中参与分析,并利用代码生成器在生成目标代码的同时根据相应的分析结果直接生成对应的测试用例.该方法将测试用例和目标代码生成统一到编译器中,避免了独立的测试用例自动生成工具在获得编译器相关分析结果时而导致的接口开销.同时,通过对源程序行号信息的跟踪,使得测试用例在无法通过测试时能够很快定位出错位置,以方便程序开发者修改.最后,通过一个示例程序说明了该方法的具体实现过程,证明了该方法的有效性.     

用词/语法分析器生成器实现软件系统的输入

以软件系统输入模块的构造为例，提出了词／语法分析器生成器的一种非编译器构造的应用，阐述了用词／语法分析器生成器实现数据输入的优点，讨论了从数据的形式描述到数据输入的过程与设计原则，并通过实例强调了该方法的核心思想。     

在RAD中实现代码自动生成

针对MDA中的两个重要转换之一——PSM到应用程序代码的转换,提出了一个基于XSLT技术的代码自动生成器设计方案,用来实现MDA的代码自动生成。此外,对代码生成器的输入、代码生成器的自动生成原理进行了详细讨论;最后给出了一个在RAD中如何采用代码自动生成器生成代码的例子。     

JavaCC及其在搜索引擎技术中的应用研究

搜索引擎中的HTML文档处理器和查询分析器都需要对特定格式的文本做词法分析和语法分析，以便构建出相应的数据结构。如果手工来编写这些分析程序，不仅编写代码工作量大，而且增加了测试的负担。本文研究了JavaCC的使用步骤和特点，并使用JavaCC构建了一个HTML文档处理器和一个查询分析器。实践表明，使用JavaCC能够大大缩短开发文本分析程序周期。     

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。     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

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.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.