CAN总线设备在DCS中的应用

为实现DCS对CAN总线设备的互联,对CAN总线及接口设备进行了研究,提出采用CAN网关设备将CAN总线信息转为Profibus-DP总线信息,并通过ECS-100的DP总线接口卡对CAN网关设备进行设置的方法,实现DCS对CAN总线设备的监控.实际应用表明,采用Profibus-DP总线通信的方式对CAN总线设备进行监控,实现了数据的交互,满足CAN总线设备对数据安全、高效的通信要求.     

CAN总线在石油仪器组合导航系统中的应用

基于DSP + FPGA结构的石油仪器组合导航系统中CAN总线系统设计,为了使数据能够在整个CAN总线网络协调、有效、快速、稳定的传输,提出了一种使用FPGA作为CAN总线节点结构中的核心处理器的设计方法;CAN控制器采用具有SPI接口的MCP2515,利用FPGA实现MCP2515的初始化、数据的发送和接收,实现了DSP处理器的CAN总线扩展应用;该方法由于把CAN节点控制的大量的工作交给FPGA实现,DSP只需要对FPGA中CAN数据接收FIFO和CAN数据发送FIFO进行读写操作,即可完成CAN总线的数据读写操作,大大减轻了DSP的数据处理压力;试验测试及产品应用表明,该设计有效、稳定可靠、可扩展性好,易于修改和移植,具有较强的工程实用价值。     

基于FPGA的嵌入式Ethernet-CAN通信转换卡设计

为实现CAN总线与PC通信,便于CAN总线数据的远程监控,提出一种新的基于现场可编程门阵列（FPGA）的多路CAN总线转Ethernet接口方案,以嵌入FPGA的NiosⅡ作为主控制器,MCP2515为CAN总线控制器,88E1111为以太网PHY芯片。利用可编程片上系统（SOPC）技术搭建了系统的硬件模型,在NiosⅡ IDE软件开发环境中,完成CAN控制器、以太网初始化和Ethernet-CAN转换程序。以数控系统中交流伺服驱动器为应用背景,实验结果表明：该转换卡完全满足以太网和CAN总线通信要求,方便地将CAN总线数据接入工业以太网,用户通过网络可方便地实现对工业底层的监控。     

一种CAN总线光纤传输接口设计

在分析CAN总线双绞线和光纤传输特点的基础上,提出一种基于光纤收发一体模块及CAN总线控制器SJA1000的光纤传输接口设计方案;详细介绍光纤收发器的选取及传输接口的实现;根据光纤收发一体模块对信号源时钟提取的要求以及CAN总线的非破坏性总线仲裁的特点,设计了一种CAN总线信号编解码方法,并用FPGA加以实现;通过实际的通信实验验证了设计方案的正确性,并根据实验数据对CAN总线在两种介质下的传输性能作了比较.     

基于LabVIEW和CAN总线的吸收式制冷机组数据监控系统

吸收式制冷系统将是制冷技术的重要发展方向。针对吸收式制冷系统管线长、设备复杂、监控点多、监控点分散的特点,设计了一种基于LabVIEW和CAN总线的分散式参数采集和控制系统。该系统采用CAN总线技术,开发了具有模拟量采集和控制的 CAN 节点,实现了对吸收式制冷系统的数据采集和参数控制,并利用上位机LabVIEW软件对采集到的数据进行运算处理,实现对系统运行状态的实时监控。采用CAN总线技术组成的控制系统,实现了控制系统的彻底分散,使系统结构简单、工作稳定,能实现多节点信号的实时通信与监控。     

基于CAN总线的遥测数据处理模块软件设计

随着飞行器电子综合化技术的发展,数据总线在飞行器中得到大量应用;为满足某飞行器总线系统测量的需求,文章设计了一种基于CAN总线的遥测数据处理模块;硬件部分主要由CAN总线驱动器模块、DSP数字信号处理模块、FPGA逻辑处理模块组成;软件设计包括TMS320F28335的初始化,CAN总线数据处理和外部中断处理三部分;该模块用于某飞行器双路CAN总线数据的采集及处理,并经过了多次飞行试验验证;该模块简化了系统设计,实现了高速、可靠的CAN总线遥测数据处理。     

VxWorks系统下CAN驱动的设计与优化

为在VxWorks系统下实现龙芯3A3000主板的控制器局域网(CAN)总线通信,采用SJA1000T设计基于PCI总线的8通道CAN通信板,并提出相应的驱动设计和优化方案。对龙芯3A3000处理器的驱动进行优化,在发送数据时禁用CAN而使用查询方式发送,在接收数据时中断服务程序对所有通道进行遍历查询,以提高中断利用率,在创建设备函数时根据PCI总线信息识别每个CAN通信板,以确保系统中不同CAN通道拥有唯一的通道号。实验结果表明,该驱动方案运行稳定,数据传输安全可靠,经优化后能够有效降低CAN通信板的中断次数,提高CAN总线的通信速率,避免多板环境下故障板卡干扰正常板卡,提高了系统的健壮性。     

CAN总线技术在PROTOS70卷接机组上的应用

介绍了卷烟厂信息化建设中底层设备采用CAN总线进行分布式控制和数据集中处理的必要性,在PROTOS70卷接机组上CAN总线的连接方式,每个设备需要接收的数据和发送的数据,通过CAN总线通信完成数据发送与接收,实现集中处理与分散控制。介绍了MLP监控系统和CIS质量检测系统、SRM重量控制系统、紧头跟踪控制系统、故障显示器的CAN总线节点设计方法。采用CAN总线技术实现了卷烟机上设备分布式控制,实际运行效果稳定可靠。     

气体泄漏监控系统中CAN总线研究

分析了变电站气体泄漏监控系统的整体结构。从CAN总线的硬件设计、Linux系统下CAN总线驱动程序、应用层通信协议等方面探讨了CAN总线的多路选择扩展方式,从实时性与可靠性等方面分析了CAN总线通信的性能。     

基于DSP和FPGA的CAN总线通信系统设计

为了提高高速条件下数据传输的稳定性和可靠性,文章提出了运用DSP与FPGA相配合的方式,控制CAN总线实现数据传输;系统采用SJA1000作为CAN总线控制器;采用PCA82C250作为CAN总线收发器;采用特有并行处理方式的FPGA实现对CAN总线控制器读写、使能等信号的控制;采用数据处理单元DSP与CAN总线控制器直接进行数据传输,省去了数据在DSP与FPGA之间传输的时间;采用两片74LVC4245完成3.3 V TTL标准信号与5 V COMS电平信号之间的转换;实验结果表明,系统数据传输过程稳定可靠,可以基本满足高速信号的处理与传输要求.     

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。     

基于QTE的蒙古文显示机制研究与实现

蒙古语言是中国蒙古族使用的通用语言,由于蒙古文区别于其他文字的书写方式和其自身变形机制等特点,在很多通用的文字处理引擎中都不被支持。在嵌入式产品开发与应用领域中Linux加QTE已经成为流行方式。该文给出了一种在QTE环境上实现基于标准Unicode的蒙古文点阵显示和变形算法, 并自定义了支持蒙古文的QTE组件,扩展了QTE功能,为在Linux加QTE方式的嵌入式体系结构中处理蒙古文提供了一种解决方法。     

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.     

基于AD9626的模拟信号采集存储卡设计

自然界的绝大部分信号都是以模拟的形式存在,因此模拟信号的采集转换存储在数字时代十分关键。文章讨论了在雷达信号处理领域基于AD9626的AD采集存储卡的设计原理、硬件结构和程序设计与芯片配置等问题,为今后相关领域的研究提供了可参考的方案。