并联式太阳能热泵热水器控制系统设计

阐述了并联式太阳热泵热水器是最易受推广使用的太阳能热泵热水器类型;针对23目前并联式太阳能热泵热水器存在的集成化控制问题,分析了并联式太阳热泵热水器控制系统的控制要求,采用水位、温差与时间相结合的控制方法,以ATmega48单片机为核心,研究了控制系统的工作原理、硬件结构及控制数据流程;系统能够根据天气、水温等不同情况自动选择太阳能机组或空气能热泵机组来制取热水,并且具有主要设备的故障自诊断功能、压缩机延时保护功能及智能化霜功能,提高了该热水器的稳定性和低温制热效率;测试结果表明:使用该集成系统后,系统平均能源利用率提高了约23%。     

热泵热水器测试生产线的设计与实现

在分析热泵热水器运转测试项目的基础上,首先提出了测试生产线的设计要求.重点阐述了测试系统的软硬件原理.系统基于RS485总线,以AVR单片机为主体构成一主多从的总线型结构,设计了测量仪硬件及主控机的总线接口,并给出了通信协议.在此基础上,介绍了主从机的软件设计和上位机的软件功能.     

DDOS防火墙性能测试的研究

在大型网络的骨干网络DDOS攻击的防护中,DDOS防火墙性能的要求变得越来越高,性能测试也成为防火墙测试工作重要的一部分。结合DDOS防火墙性能指标的内容探讨了性能测试用例的设计方案、性能测试过程中常用的测试工具和测试执行的基本方法,并提出了一种使用测量不确定度评定测试指标值的方法。     

防火墙性能测试研究

防火墙作为应用最广泛的网络安全产品,其本身的性能如何将对最终网络用户得到的实际带宽有决定性的影响,因此对防火墙性能的要求越来越高,性能测试也成为防火墙测试的最重要的一部分。本文结合防火墙性能指标探讨了性能测试指标、常用测试工具,并研究提出了使用测量不确定度评定测试指标值的方法。     

基于主动测试的流媒体业务性能测量工具设计与实现

流媒体业务是推动下一代互联网发展的主要动力之一,对其性能的测量极为重要。根据流媒体业务性能测量的要求,借鉴主动测试技术,从端用户角度提出了合理反映流媒体业务性能的指标,分析了精确测量性能指标的方法,从而设计并实现了基于主动测试的流媒体业务性能测量工具,并对设计的关键问题做了分析。测量实验表明测量工具运行健壮,测量数据精确,取得了理想的效果。     

基于Crystal Ball软件对测量不确定度的评定

本文首先介绍了测量不确定度的概念,接着阐述了测量不确定度在实验室检测过程中的作用,然后介绍了测量不确定度的方法和步骤,本文介绍了使用Crystal Ball利用蒙特卡罗方法在测量不确定度的应用的步骤,通过软件的使用可以解决在测试实际工作中评定测量不确定度遇到的困难。     

便携式制动性能测试仪示值误差的不确定度分析

依据JJF1168-2007《便携式制动性能测试仪校准规范》和JJF1059-1999《测量不确定度评定及表示》,对便携式制动性能测试仪示值误差测量结果进行了不确定度评定,通过阐述测量过程中产生的各分量对示值误差的影响,得到了测量结果的扩展不确定度。     

热泵热水器控制器的设计

介绍了热泵热水系统的工作原理。详细阐述了以松翰公司的SN8P2308微控制器为核心的热泵控制器硬件系统的设计。结合热泵热水器的控制要求,采用模块化、层次化的软件设计方法,实现了多路温度数据的采集和热泵在各种系统参数下运行的控制。     

恒温燃气热水器的模糊推理算法

基于模糊推理技术的研究,从理论上阐述了燃气热水器的工作流程,以及采用的最新气阀--蝶阀的特点;并介绍了模糊控制器的设计过程、原理及参数的整定方法.实际测试结果表明,该系统控制精度高,动态性能好,控制性能好.     

泛华恒兴电源测试新品亮相上海慕尼黑电子展

<正>近日,北京泛华恒兴科技有限公司(简称:泛华恒兴)携多行业测试新品亮相2012上海慕尼黑电子展。尤其是针对电源测试测量行业用户,泛华恒兴推出了为客户量身打造的PowerMASTER电源自动化测试台,受到了参会者的广泛关注。泛华恒兴推出的PowerMASTER电源自动化测试台倡导可靠、精准、自动、高效的电源测试,已为国内外     

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.