VHDL与电子自动化

随着电子设计自动化（ＥＤＡ）时代的到来，传统的硬件设计方法已经无法满足人们的要求了，ＶＨＤＬ语言作为一种高级硬件描述语言，由于它能以形式化的方式描述数字系统，从而大部分繁琐的工作可以由计算机来完成，而设计师能专注于整个系统的设计。ＶＨＤＬ的出现为电子设计自动化（ＥＤＡ）的发展打下了坚实的基础，也给硬件设计领域带来一场革新。本文就此介绍了ＶＨＤＬ语言的基本构成和语句，及使用ＶＨＤＬ语言设计的优点。     

硬件描述语言VHDL的表述特点及其综合过程

ＶＨＤＬ是一种具备形式化，层次化和规范化的硬件描述语言。它能针对设计实体的多方面特性给出了其不同层次上的表述方式；结构描述，数据流描述和行为描述。本文介绍了ＶＨＤＬ的表述特点及其综合过程。     

Verilog HDL与逻辑系统设计

ＶｅｒｉｌｏｇＨＤＬ与逻辑系统设计北京航空航天大学ＥＤＡ实验室夏宇闻随着计算机和半导体工艺技术的发展，数字逻辑电路的设计正悄悄地进行着一场重大的革命。这场革命的核心是采用硬件描述语言（ＶＨＤＬ或ＶｅｉｌｏｇＨＤＬ）来设计复杂的数字逻辑系统。早在七十年...     

VHDL语言行为描述划分的研究与实现

硬件描述语言行为级划分的处理对象是行为级的硬件描述，其结果可以用来指导综合中数据通路的设计实现及后续综合。本文研究ＶＨＤＬ语言行为描述划分的内容和系统设计方法，提出了一种类层次可变权的ＶＨＤＬ语言行为划分算法，该算法将单级层次划分算法与多级层次划分算的思想统一到一种算法中；针对行为划分的目标特点本文在划分因素评估中提出了规模因素的思想。     

VHDL语言中断言语句及其综合方法研究

国内外学者普遍认为，硬件描述语言ＶＨＤＬ中断言语句是面向模拟的，其不能综合或不要综合，综合系统应忽略或不支持。本文给出了相反的论点：ＶＨＤＬ中断言语句应该综合，其中限制条件的补表达式可作为随意条件用于综合时化简。文中论述了综合断言语句的合理性，必要性和方便性，并给出了综合并行和串行断言语句的方法。     

行为驱动的VLSI设计方法

本文提出在ＶｅｒｉｌｏｇＨＤＬ硬件描述语言和Ｖｅｒｉｌｏｇ－ＸＬ模拟器环境下，实现行为驱动的ＶＬＳＩ硬件结构设计方法，从而生成寄存器传输级的数据通道和控制通道，给出了智能机械手实时控制主用处理器结构设计实例。     

VHDL——标准化的硬件设计语言

本文介绍了用ＶＨＤＬ语言来描述硬件模型的方法，结合实例说明这种高级硬件设计语言在逻辑设计中的灵活性和可移植性，并指出ＶＨＤＬ将推动逻辑设计的标准化     

标准硬件描述语言VHDL

ＶＨＤＬ（ＶＨＳＩＣ Ｈａｒｄｗａｒｅ Ｄｅｓｃｉｐｔｉｏｎ Ｌａｎｇｕａｇｅ，ＶＨＳＩＣ硬件描述文）作为ＩＥＥＥ标准设计语言，是电子ＣＡＤ技术发展的重要里程碑。ＶＨＤＬ语言正在逐步为广大电子设计师了解和掌握。本文主要介绍了ＶＨＤＬ语言的特点、构件和描述风格。     

VLSI设计仿真系统分析编译器的研制

仿真在国内外都是关键攻关项目，而研究仿真的办法基本上都是用某种语言对问题进行描述，然后编译，根据需要产生仿真结果。但问题的描述语言品种很多，如果针对每种语言都研制其编译器，那么花费许多的人力、财力、不划算。因此，本文介绍一种用于ＶＬＳＩ设计仿真中的硬件描述语言（ＨＤＬ）到Ｃ语言的转换实例，其设计思想及实现办法适于各类问题描述语言分析编译器的研制     

V2C＋＋——一个用C＋＋实现的VHDL翻译型模拟器

由于面向对象的Ｃ＋＋语言更贴近描述硬件对象的ＶＨＤＬ语言Ｃ＋＋实现翻译型ＶＨＤＬ模拟器，并利用Ｃ＋＋本身的编译器的优化功能，可以得到运行的时间和空间方面效率较高的ＶＨＤＬ模拟器，Ｖ２Ｃ＋＋的原型设计和初步实践表明，用Ｃ＋＋实现ＶＨＤＬ翻译性模拟器比解释性模拟器具有较高效率，利于较大规模的电路的模拟。     

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).