基于ADG1607十六通道湿度测量电路设计

为了解决多路湿度测量各个通道系统误差一致性以及简化ADC电路的问题,采用两片ADG1607电子模拟开关和一片AD7792数模转换器构成信号测量电路,通过MCU控制模拟开关阵列进行切换,实现十六路湿度模拟信号的采集,按照预设的顺序分时送入AD转换为数字量输出,通道切换需要稳定时间,经验值采取10ms。在输入电路加入合适的电阻和电容组成RC滤波电路消除开关切换带来一些毛刺干扰,同时引入正确的放电回路,防止电荷积累而影响测量精度。对电路进行测试,结果表明,各通道之间最大误差为0.17%,通道一致性评价为,相对误差0.003,平均绝对离差0.002475,标准差为0.095。该电路已经在实际的自动气象站中长期应用,无机械触点的模拟电子开关能够很好地适应频繁切换,其整体测量性能指标满足气象观测设备对湿度测量准确度的要求。     

插管式多层地温测量传感器设计

介绍了四线制引线Pt100电阻器用于实现多层地温测量传感器的具体设计方案,该方案主要包括AD采样电路、多路切换测量电路、牛顿迭代法计算温度值以及插管式结构设计,并进行算法验证和实际测量对比,经过验证,采用牛顿迭代法计算的温度与查表法得到的温度误差在0.015℃以内,实际测量与标准温度误差在0.2℃以内,该方案完全满足目前对地温测量的要求。     

基于LabVIEW的高精度铂电阻测温系统设计

针对铂电阻测温的特性结合虚拟仪器技术,设计了一种高精度温度测量系统;采用四线制恒流源温度测量电路克服由于铂电阻引线带来的误差,同时利用LabVIEW软件完成曲线拟合,最后对温度测量系统误差进行了分析;测试结果表明,系统具有测量精度高、可靠性高、使用灵活等特点,当被测温度范围在8℃～100℃之间,测量的绝对误差小于±0.1℃,可广泛使用于要求高精度温度测量的领域。     

基于DDS的BJT放大器特性测试系统的设计

由BJT构成的放大器电路目前广泛应用于各类电子电路,而输入、输出电阻,增益,截止频率,幅频特性等作为BJT放大器的重要性能指标,对电路特性的测量和工作状况的判断具有重要意义。本文设计了一种基于STM32和DDS的BJT放大器特性测试系统,其中包括硬件电路搭建和软件设计。系统通过按键实现多种测量模式的切换,利用采样电路完成数据采集,通过STM32进行数据处理并将相应性能指标参数显示在OLED上。测试结果证明,在误差允许范围内系统实现了对BJT放大器电路特性的有效自动测量。     

地表温度遥感中大气平均作用温度估算模型研究

大气平均作用温度Ta是地表温度遥感单窗算法中一个关键的参数,利用2008~2011年全国123个探空站点资料,针对大气水汽量的垂直分布特征,分析了利用近地层气温T0估算大气有效平均温度的可行性;进一步分析了T0和Ta之间的相关性,建立了适合我国地区大气平均温度估算的最佳模型Ta=44.97098+0.80512 T0,模型的决定系数R²为0.859,均方根误差为4.198 K。通过对44幅HJ\|1B/IRS热红外图像地温反演的敏感性分析,结果表明:模型估算的Ta用于地表温度反演时的误差为1.734 K;当大气透射率τ很小时,模型估算的Ta误差对地温反演很敏感,较小的估算误差会给地温反演带来很大的误差;随着大气透射率τ的增加,Ta的估算误差对地温反演的敏感性逐渐降低。
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便携式代谢率检测系统的误差分析及改进

通过对便携式代谢率检测系统误差模型进行蒙特卡罗仿真,得到最终误差指标,通过改进测试电路和多传感器数据融合,在非标定条件下实现了仪器的代谢率测试准确度要求。针对温度传感器测试模块进行了误差分析和改进,精度达到0.15℃(RMS)。通过极大似然估计对改进电路进行数据融合,保证整个测试过程中温度测试误差在0.124℃(RMS)以内,满足了批量生产的高准确度要求,避免了标定过程,降低了生产成本。     

温度湿度无线测控系统设计

介绍了具有无线功能的温度湿度测控系统的工作原理、硬件结构设计、试验结果。该系统以温度湿度传感器为核心,利用无线收发器构成无线扫描控制系统,实现了温度0.6℃误差和湿度5%RH误差的测量。该系统体积小、功耗低、电路简单,可以方便安装和实现实时监控。     

矿用随钻轨迹测量系统误差补偿方法

介绍了随钻轨迹测量系统构成和测量原理,从传感器自身误差、工况环境误差、传感器安装误差3个方面详细阐述系统误差来源及其补偿方法。通过模拟水平定向钻进物理场景并分析比较误差补偿前后的姿态角可知,对不同误差源作出相应的误差补偿可以提高姿态角测量精度。     

时间间隔测量的高精度技术研究

针对高能物理研究、激光测距等对时间测量具有高精度要求的领域,采用时间周期计数粗测和时间-电压转换精测相结合的测量方法,设计了时间间隔测量系统,其主要由时间-电压转换电路、脉冲生成电路等组成,利用对电压量的精准测量转化为高精度的时间量.对系统供电进行优化,同时满足低功耗和低噪声的需求;分析了环境和电路板自热造成温度变化时对测量过程带来的误差,提出利用自校准技术消除温度影响.该系统具有测量范围高达20 s,测量分辨率为0.2 ps的优点.     

多目标环境下分布未知的系统误差估计方法研究

针对多传感器多目标跟踪过程中分布未知的系统误差估计问题,对于系统误差在均匀分布和非均匀分布之间保持不确定假设下的估计方法进行了研究,提出了两种不同的误差估计方法,推导出相应误差估计方法的误差计算公式.针对两种方法在不同的系统误差分布假设下所表现出的估计性能和特点,提出了一种将两种方法结合起来的系统误差估计算法:通过合理选择阈值门限η,能够在多传感器多目标且系统误差分布未知的复杂环境下对两种误差估计方法自适应的进行切换,从而充分发挥两种方法各自的优点.同时可以对算法中估计方法模块进行扩充,以适应更复杂的误差分布情形下的多传感器系统误差自适应估计.     

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.     

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。     

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.