小型风机叶片结构损伤识别实验模拟研究

搭建小型风机叶片振动检测实验平台,采集风机叶片振动响应数据,利用自互功率谱法辨别叶片损伤前后的模态参数,通过实验数据对比风机叶片损伤前后固有频率的变化,当风机叶片发生损伤时,其各阶固有频率会下降,且随着损伤程度的增加,各阶固有频率的下降幅度越大,并利用轴向振型差法对叶片损伤进行了定位,在实验室条件下完成了风机叶片结构损伤的识别。     

基于声发射信号的风机叶片裂纹定位分析

为能够及时有效地监测并识别风机叶片裂纹的位置以及强度,讨论了风机叶片上声发射传感器测点优化布局方案,以及基于无线传感网络的信号采集实现,探讨了声发射信号分析和特征提取方法。在分析现有裂纹定位方法特点的基础上,提出了一种针对声发射信号进行小波分析判别风机叶片裂纹位置及其强度的方法。通过实验数据验证了该方法不仅能够实现裂纹位置及其强度的定位,而且与传统方法相比该方法提高了精确性。     

基于IMC-PID控制的风机叶片颤振控制研究

针对风机叶片在颤振情况下严重影响风机的运行安全和发电效率的问题,设计了一种基于内模PID控制(IMC-PID)的振动控制方法,仅需调节较少控制器参数,就能有效地抑制叶片颤振并获得良好的闭环动态特性.首先使用递推最小二乘法对高阶对象模型进行降阶,然后利用IMC-PID方法设计控制器.仿真结果表明:在风机叶片颤振控制中,IMC-PID控制器与传统PID控制器相比,控制器整定参数少,且具有更好的动态特性和鲁棒性.     

关于锅炉风机运行中常见故障的原因及处理措施研究

锅炉风机在运行中,由于长期运行可能导致零部件磨损、老化,出现故障问题,在不同程度上影响着锅炉风机正常运行。就锅炉风机常见故障来看,地脚螺栓折断、叶片非工作面积灰处理或是风道系统振动等因素导致的引风机振动问题;润滑不足、轴承异常等问题都可能导致轴承温度升高,加剧轴承磨损和老化,出现故障问题。这些常见的故障问题将会影响到锅炉风机的正常运行。基于此,本文就锅炉风机运行中常见故障进行分析,为了保证锅炉风机可以正常运行,就需要在深入剖析故障原因基础上,寻求合理的处理措施,避免对生产作业活动带来不良影响。     

小波包分解与神经网络风机齿轮箱故障诊断

齿轮箱作为风机传动系统重要的机械部件长期工作在恶劣环境中易于发生故障。针对风机齿轮箱产生的振动信号具有非平稳、瞬态、不确定性、以及外界干扰因素等特点，提出了小波包与改进的BP神经网络相结合方法。首先提取原始振动信号的时域波形，利用小波包对于时域特征值进行分解，将小波包分解后的子频带能量进行归一化计算，并作为BP网络的输入特征向量，其次创建BP故障模型，通过改进的优化算法对神经网络的权值和阈值进行全局寻优，最终使得对故障类型进行精确的判断，提高了故障诊断效率。仿真结果比较了两种优化算法的性能指标，得出改进的蚁群算法(MMA)优化算法识别精度更高，误差相对较小，收敛速度更快，验证了方法的有效性和可靠性。     

冷却塔风机叶片运行状态监测技术研究

在阐述冷却塔风机运行状态监测技术现状以及对风机叶片断裂原因进行分析的基础上,提出一种新型非接触式冷却塔风机叶片运行状态监测方法--叶尖计时监测法,并将叶尖计时监测法与单片机技术相结合,研制出一种非接触式冷却塔风机叶片运行状态监控系统,实现在叶片发生断裂、变形时监控系统控制风机停机并报警,从而预防叶片事故的发生。生产实践证明,此监测方法明显提高了风机运行状态监测的可靠性,能有效地避免叶片故障的发生,具有良好的推广应用价值。     

基于LiDAR与可见光融合的自动风电叶片巡检方法

传统风机叶片使用人工吊篮、望远镜、手动操控无人机的方式进行巡检,存在巡检难度大、巡检效率低、拍摄数据规范性差等问题。为此,提出了一种在无人机平台上基于LiDAR与可见光融合的风机叶片自动化巡检的方法。通过融合可见光相机、激光雷达采集的多源数据自动规划风机状态的智能感知和无人机航线,可实现拍摄风机叶片的不同部位（前缘、后缘、迎风面、背风面）并选择最佳角度、最佳距离,在保证巡检安全的前提下极大地提升了叶片巡检的质量,同时降低了风机巡检人员的作业难度,提升了风机叶片的巡检效率。     

DCS信号电缆的屏蔽接地探讨

某电厂机组调试间发生一次六大风机振动信号全部瞬间跳变导致六大风机跳闸引起机组MFT,经检查是由于风机振动控制拒的接地不合理引起,处理好接地后振动信号正常后未发生跳变情况,文章分析了产生干扰信号的原因及抑制方法。     

基于WSN的煤矿风机振动监测系统

设计了一种基于无线传感器网络(WSN)的煤矿风机振动监测系统。该系统用温度传感器、振动传感器采集煤矿主风机设备的运行状态数据,借助于无限传感网络将数据统一传送至监测中心的上位机,实现对煤矿风机设备的远程监测,并在此基础上运用支持向量机对采集到的风机振动信号做趋势预测。     

果蝇优化算法融合SVM的风机叶片损伤识别研究

为提高风机叶片裂纹损伤和边缘损伤识别的准确率,提出使用果蝇优化(FOA)算法和支持向量机(SVM)相结合的方法。使用硬件系统采集两类损伤故障的声发射信号,然后对信号进行小波处理,提取能量特征,根据能量特征信息,建立支持向量机模型,测试其准确率;采用果蝇优化算法优化支持向量机参数,使模型损伤识别更准确,并将优化后模型识别结果与粒子群优化(PSO)算法优化支持向量机后的识别结果相比较。仿真结果表明,使用果蝇优化算法优化后的支持向量机模型的识别精度更高,能够准确地实现对风机叶片损伤的识别。     

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.     

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。     

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。     

A human-computer interface for non-computer specialists

The COM teleconferencing system was designed to be easy to use for both beginners and people with much computer experience. A number of design choices in organizing the human-computer interface were considered very carefully. These design problems are not unique for teleconferencing applications, but will appear in many other developments of human-computer interfaces for non-computer specialists. This report discusses naming conventions, menu format, user commands, help facility and the treatment of ‘type ahead’ from the users.     

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.     

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.     

Call for papers Special issue on Modeling and control technologies for civil,energy,and power systems

正The control of civil,energy,and power systems presents significant new challenges for modeling and control theory.The purpose of this special issue is to provide a forum for researchers and practical engineers to discuss the recent advances in modeling and control technology development for civil,energy,and power systems.Prospective authors are invited to submit their original contributions with the focus on theory or applications of modeling,control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate and promote academic exchange between Chinese and foreign scientists everywhere.