双经纬仪三维坐标测量系统设计

在大尺寸坐标测量领域,双经纬仪坐标测量系统因其测量精度高、移站方便、非接触式测量等优点应用广泛。针对工业现场大尺寸精密测量的需求,本文基于双经纬仪前方交会测量原理,分析了两种不同的经纬仪系统标定方法,利用面向对象的VC技术设计实现了经纬仪系统的标定、通讯、测量、基本几何元素拟合等功能,并完成了系统人机交互界面的设计和基于ADO访问技术的数据管理。实验结果表明:该坐标测量系统测量精度高,操作高效实用,可广泛应用于工业现场大尺寸坐标测量中。     

用于机器人柔性坐标测量系统的视觉传感器设计

视觉传感器作为机器人柔性视觉坐标测量系统最重要的组成部分之一,直接影响测量系统的精度、适应性.针对机器人柔性坐标测量系统的需要,提出了两步法测量空间形状的原理和数学模型,设计了一种线结构光单目视觉传感器,对其测量结果进行了误差分析,并用实验的方法证明了该传感器精度适中,体积小,重量轻,可以满足工业现场在线测量的需要.     

点阵测头成像视觉坐标测量系统的研究

柔性三维坐标测量在工业现场测量有较多应用.分析多目标点透视成像原理的基础上,提出了点阵测头成像视觉坐标测量的概念,给出系统完整的三种数学模型及求解方法.设计了一种实用测头,基于单台面阵CCD摄像机实现由三种类型测头组成的视觉测量样机.在距离摄像机1 000 mm,样机进行实际测量,并与三坐标测量机的检测结果进行比对.测试结果表明在摄像机成像面平行的两个方向的测量精度高于摄像机轴向测量精度.     

基于遗传算法的wMPS系统布局优化研究

室内空间测量定位系统(wMPS)是一种采用光平面交会的分布式大尺寸室内空间坐标测量系统.发射站的布局直接影响着该测量系统的测量误差、测量精度和其使用效能,而传统的L、C等测量模型在实际过程中受现场条件限制,测量精度比较低.为优化测量系统的网络布局,从该系统的空间多角度交会测量模型入手,以测量精度为优化目标,采用遗传算法作为优化工具,建立了以三维坐标数据对光平面扫描角的导数为关键的定位误差模型,以协方差来反映测量精度,更简单、直接地实现了在指定测量空间下的最优网络布局.最后设计了实验进行验证,实验结果表明该方法能有效优化布局,提高测量精度.     

基于LabVIEW的激光双频外差干涉纳米位移测量系统

工业的发展对位置测量精度提出了越来越高的要求。测量外差干涉仪由于其自身测量范围广、测量速度高、稳定性好、分辨率高的特点,在纳米测量领域中得到广泛的应用。提出了一种基于LabVIEW的外差干涉纳米位移测量系统,该系统采用外差干涉仪作为位置检测单元,利用LabVIEW图形化编程语言开发了纳米精度位移测量系统。该系统可广泛应用于纳米计量和超精密测量领域。     

基于立体视觉的接触式三维测量系统

传统的三维接触式测量方法存在着速度慢、测量范围受限等缺点,而纯粹的非接触式测量方法则存在着特征边缘无法获取的问题。结合两种测量方法,设计了一种新的三维测量系统,该系统采用立体视觉技术对接触式测头的空间位置和姿态进行定位,进而间接计算接触式探针针尖位置来完成空间点的三维坐标测量。实验结果表明:系统测量精度优于0.2 mm,能够应用于工业现场进行复杂工件的典型几何特征检测和模型重构。     

基于旋转平面激光扫描测角的新型坐标测量系统

为了满足现代制造业中超大尺寸测量高效高精度的要求,以空间角度交汇测量原理为基础,提出了一种新的三维坐标测量系统.介绍了该系统的测量原理,分析了系统的几何模型.结合测量原理和结构对系统精度的影响,对系统的重要部件进行了结构设计分析,完成整个系统的设计.最后通过实验数据验证该系统的可行性,该系统在6m的测量距离精度可达±0.15 mm.     

基于机器视觉的二维小尺寸精密测量系统

针对原有万能工具显微镜存在的瞄准麻烦、读数过程烦琐、人员主观误差相对较大、长期工作劳动强度大等缺点,设计了一种对万能工具显微镜进行改造而成的二维精密测量系统;该系统引入了机器视觉技术进行自动测量对准,采用光栅传感器提供坐标系以检测尺寸,既保持了原有仪器的准确度高、抗干扰能力强、长期稳定性好、应用范围广等优点,又提高了测量的自动化水平,同时具有较高的性价比;该系统很适合工业上零件的精密测量,具有较高的应用价值和广泛的应用前景;文中设计的测量系统测量范围为25 mm×25 mm,其测量精度可达5 μm.     

C-V模型与工业CT相结合的几何测量方法

针对工业生产中复杂封闭内腔几何尺寸很难测量的问题,提出一种基于C-V模型的工业CT几何测量方法.首先利用C-V模型提取目标边缘坐标点的有序链码,然后利用Green定理和欧氏距离公式计算目标区域的面积和周长.在提取目标边缘坐标点的步骤中,把边缘灰度先验知识融入C-V模型以提高测量精度;在计算目标区域的面积和周长的过程中,合理地选择目标边缘有序坐标点和插值有序坐标点,再一次提高几何测量精度.实验结果表明,与2DFacet模型测量方法相比,文中方法测量精度约提高1个数量级;并已将该方法应用于实际中.     

铂电阻温度计及其测量精度的分析

铂电阻温度计是温度测量中最常用的温度传感器,其测量精度是工业精密测量中备受关注的重要指标。本文在研究铂电阻温度计测温特性的基础上确定了其测温公式,并证明了利用测量公式计算测量温度可以提高铂电阻温度计的测量精度。采用本文所提测温公式计算得到的温度偏差在±0.05℃范围之内,测量精度比查表法高了一个数量级。此方法不需增加额外成本和仪器,经济实用性高。     

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.     

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.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

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.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

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。