基于模型驱动的机载嵌入式软件应用

摘　要 传统的软件开发方法已无法应对机载嵌入式软件开发面临着严峻的挑战,基于模型驱动的软件开发方法将业务模型和软件实现平台分离,有效的提高了机载嵌入式软件开发效率。本文对两种机载嵌入式软件设计方法进行了比较,以基于SCADE平台实现的自动飞行控制系统的自动驾驶仪模态控制软件为例,并对SCADE自动生成代码与手工编写代码的执行效率进行了比较证明前者更优,验证了基于模型驱动开发的软件设计方法能有效提高机载嵌入式软件的开发效率。     

基于SCADE的无人机自主导航飞行软件设计

该文研究了一种无人机飞行控制软件设计方法,利用高安全性的应用程序开发环境-SCADE(Safety-Critical Application Development Environment)开发无人机自主导航功能模块的软件;按照SCADE开发嵌入式软件设计流程,自动生成可直接面向工程的高安全性嵌入式代码;并通过代码的效率测试和安全性测试,验证了在SCADE环境下进行无人机软件开发的优越性;由此得出SCADE很大程度上实现了软件开发的自动化,节约了开发成本和开发时间,并具有很高的安全性特征.     

SCADE平台下的图形化设计和代码自动生成

随着航空机载软件功能和复杂性的提高,采用传统的人工编码方法来已不能满足其效率和安全性要求,因此寻求一种更有效的航空机载软件设计方法势在必行。本文研究了一种航空机载软件开发方法—高安全性开发环境SCADE,并以飞机自主导航软件为例,按照SCADE软件的程序设计流程,即通过直观的图形化建模和模拟仿真自动生成可直接面向工程的安全嵌入式C代码。实验结果表明,SCADE在很大程度上实现了软件开发的自动化,节约了开发成本和开发时间。     

基于SCADE的机电管理软件开发方法研究

目前传统软件开发流程由于开发周期长、代码编写工作量大、测试复杂等问题,已经难以应对复杂的航空机载软件需求,因此需要探索更为高效的软件开发方法.本文探究了SCADE工具在直升机机电管理软件开发上的应用,并选取典型模块-燃油功能模块,进行了需求分析、建模、仿真、代码自动生成及代码测试,表明了应用SCADE开发方法的优越性,...     

基于MDA的嵌入式软件开发平台设计

针对如何快速开发高质量的嵌入式软件的问题,实现了一种基于MDA的嵌入式软件开发平台EUP。该平台根据模型驱动的软件开发方法,集成UML建模、模型验证、模拟和自动代码生成技术等,为嵌入式软件的开发提供了一个统一的开发环境。分析了铁道交叉路口系统的实例,试验结果表明EUP平台能够方便、高效地实现模型模拟和验证,为快速开发高质量的嵌入式软件提供了一种可行的途径。     

SCADE平台下C代码的自动生成

随着航空电子软件的迅速发展,传统的软件设计方法已不能满足其效率和安全性需求.为解决传统设计方法的不足,寻求一种更有效的控制软件设计方法,高安全应用开发环境SCADE应运而生.主要介绍了高安全应用开发环境SCADE的开发背景及开发特点,并以飞机飞行控制律为例,按照SCADE软件的程序设计流程,即通过直观的图形化建模建立无人机飞行控制律模型,通过模拟仿真保证设计的正确性,最终自动生成可直接面向工程的嵌入式C代码.实验结果表明,SCADE在很大程度上实现了软件开发的自动化,节约了开发成本和开发时间,体现了SCADE环境下进行软件开发的优越性.     

基于SCADE的航空发动机FADEC软件开发

机载软件开发面临复杂性、安全性和成本等方面的巨大挑战.针对某航空发动机数控系统的研制,结合FADEC软件的开发特点和目标,探索SCADE基于模型开发在FADEC软件开发中的应用.探索了两种不同的SCADE基于模型开发解决方案,基于这两种方案分别完成两个FADEC软件配置项的应用软件开发.通过模型测试、模型覆盖率分析和软件硬件集成测试验证了开发结果的正确性.提出了联合SCADE和Simulink的基于模型开发流程并明确其注意事项.分析SCADE的两种基于模型开发解决方案的适用范围以及方案选择时的考虑因素,总结分析了SCADE用于机载软件开发的优势和不足.     

基于SCADE的PID控制器设计与应用

传统的PID控制器设计通常采用手工编程来实现，不但费时费力，而且可靠性低。为解决该方法的不足，寻求一种更有效的控制软件设计方法，该文研究了一个高安全性的应用开发环境——SCADE。按照SCADE软件的程序设计流程，即通过直观的图形化建模和模拟仿真自动生成可直接面向工程的安全嵌入式代码，介绍了PID控制器在该环境下完成相应软件设计与开发的过程，并通过代码的效率测试和安全性测试验证了SCADE环境下进行软件开发的优越性。由此得出，SCADE很大程度上实现了软件开发的自动化，节约了开发成本和开发时间，并具有很高的安全性特征。     

嵌入式实时系统的快速开发框架研究

嵌入式实时开发是当今计算机应用研究的热点,该文结合模型驱动架构的系统无关模型和系统相关模型思想,提出了一种基于平台设计的快速开发嵌入式实时系统的方法:首先采用实时应用接口RTAI将嵌入式Linux改造成具有硬实时性能的实时操作系统平台;然后利用Matlab/Simulink/RTW和RTAI-Lab工具对实际系统进行快速化建模、仿真和驱动开发,并自动生成实时的可执行代码;最后将代码加载到嵌入式实时系统.通过倒立摆嵌入式实时控制器系统设计实例说明了这种方法可以有效降低系统设计复杂度,提高嵌入式软件的开发效率.     

RTW嵌入式代码自动生成机制与代码结构分析

随着代码自动生成技术的发展,基于文本规范的传统嵌入式软件开发模式逐渐被基于模型的设计方法所取代,代码自动生成技术是基于模型的开发方法中一项核心技术,而MATLAB中RTW工具箱是代码自动生成最优秀的工具,首先对基于RTW的代码自动生成机制进行了分析,研究了VxWorks目标代码的结构及变量命名规则,并从程序实时运行机制方面进行了分析,方便用户对自动生成的代码进行二次开发;采用该技术进行VxWorks嵌入式软件开发,可大大提高开发效率。     

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).