一种频率稳定的低功耗振荡器电路设计

设计了一种频率稳定的低功耗张弛振荡器电路。采用恒流源对电容两端同时充电和放电,然后将电容两端电压送入后级比较器进行判决,使得输出频率只与恒流源电流、电容以及比较器比较窗口相关。该电路采用GSMC 0.18μm CMOS工艺,在5 V电源电压以及室温条件下仿真,输出频率为123.6 kHz,平均电流消耗为2.67μA;在2 V～5.5 V电源电压和-40℃-+85℃的温度变化范围内,输出频率精度在-6.5%-1.3%范围内。     

一种带电源电压和温度补偿的振荡器电路设计

设计了一个带电源电压补偿和温度补偿的低功耗环形振荡器电路,环形振荡器采用受限于PTAT电流的反相器和普通CMOS反相器级联结构。由于电源电压和温度对这两种反相器传播延时的影响是相反的,利用这种相反的特性使得振荡器输出频率在电源电压和温度特性上得到补偿。该电路采用0.18μm CMOS工艺,测试结果显示在5 V电源电压以及27℃温度条件下,输出频率为263 k Hz,平均电流消耗为2.5μA。在3.5 V~5.5 V电源电压和-40℃~85℃的温度变化范围内,输出频率偏差在-2.3%~6.5%范围内。     

集成于无源UHF RFID标签的超低功耗CMOS温度传感器

本文提出了一种集成于无源UHF RFID标签的超低功耗CMOS温度传感器。考虑到功耗是影响标签使用的第一要素,本文结构复用标签内部电路产生的电流作为温度转换模块的偏置电流,同时采用标签内部振荡器产生的信号作为传感器计数器的时钟信号。本文设计采用SMIC 0.18 μm 2P4M CMOS,仿真结果表明：电源电压为1.5V时,室温时新增的温度传感器模块功耗仅为100nw;当温度在-20℃~80℃变化时,温度传感器分辨率为0.4℃/LSB。     

应用于RFID的超低功耗CMOS温度传感器设计

针对融合射频识别( RFlD)的无线温度传感器节点设计的需求,采用0. 18μm 1P6M台积电CMOS工艺,设计了一种低功耗集成温度传感器.该温度传感器首先将温度信号转换为电压信号,然后通过经压控振荡器将电压信号转换为受温度控制的频率信号,再通过计数器,将频率信号转换为数字信号.传感器电路利用MOS管工作在亚阈值区,并采用动态阈值技术获得超低功耗.测试结果显示:所设计的温度传感器仅占用0. 051 mm2 ,功耗仅为101 nW,在0~100℃范围内误差为-1. 5~1. 2℃.     

一种适用于RFID标签的高精度温度传感器的分析与设计

论文描述了一种集成于RFID标签芯片的高精度CMOS温度传感器,该温度传感器采用SMIC 0.18μm 2P4M CMOS工艺.利用MOS管工作在亚阈值区域时的温度特性,产生与绝对温度成正比(PTAT)的电流,替代了传统的BJT.电流控制振荡器(CCO)将PTAT电流转换成频率与温度成正比的时钟信号,该时钟信号通过计数器转换为数字信号.通过对电流源和比较器的优化设计,该温度传感器在温度范围为-20℃～50℃时误差仅为-o.1/+0.3℃.电源电压为1.8V时,工作电流小于50μA.     

集成于无源UHF RFID标签的新结构CMOS温度传感器

设计了一种集成于无源UHF RFID标签芯片的新结构温度传感器.利用高PSRR共源共栅结构的电流镜偏置电路产生两路温度系数相反的电流,实现了偏置电流对电源电压和温度补偿.与温度相关的脉冲信号由类似差分的结构产生,有效的克服了工艺偏差导致的误差.计数时钟信号由标签内部振荡器提供,振荡器频率受偏置电流控制近似与电源电压和温...     

一种低电压亚阈值CMOS基准电路的设计

利用负反馈技术设计了一款基于CMOS亚阈值MOS器件的低压高性能CMOS基准源电路。基于SMIC 0.18μm标准CMOS工艺,Cadence Spectre仿真结果表明：所设计的基准电路能在0.8V电压下稳定工作,输出380.4mV的基准电压;在1kHz频率范围内,电源噪声抑制比为-56.5dB;在5℃到140℃范围内,温度系数6.25ppm/℃。     

应用于无源RFID标签的BICMOS温度传感器

基于IBM 0.18μm SiGe BICMOS工艺,采用温度脉冲转换方式设计了一种应用于无源RFID标签的温度传感器。与绝对温度呈正比(PTAT)的电流源和电流饥饿环型振荡器产生频率与温度呈正相关的振荡信号,作为计数器的时钟信号;用数字模块对接收的帧头代码进行处理得到一个宽度为200μs的脉冲信号,作为计数器的使能信号;利用时域数字量化方式就可以得到不同温度下的数字信号。温度传感器总面积为0.03 mm2,温度在-100~120℃范围内变化时,振荡器输出频率范围由800 kHz~1.8 MHz。在1.8 V电源电压下,温度传感器平均输出电流约为13μA,芯片测试结果的有效分辨率可以达到0.864 LSB/℃。     

一种CMOS带隙基准源的设计与仿真

分析了传统带隙基准源的基本原理,并在此基础上一款CMOS带隙基准源电路。该电路基于UMC0.18μm CMOS工艺设计,利用cadence软件进行仿真。仿真结果表明,CMOS带隙基准源稳定输出电压1.22V,该电路在温度从-50-100℃进行扫描,其变化率为10.7ppm/℃,电源电压在1.7V-1.9V范围内发生变化时帯隙基准源输出电压变化很小。     

带有过温保护功能的1W白光LED驱动电路设计

基于CSMC 5V0.6μm标准CMOS工艺设计研制了一种具有过温保护功能的1W温度传感LED恒流驱动电路.该电路由恒流驱动模块和温度传感模块组成,在电源电压为5V时能提供350mA恒定驱动电流,并能在设定温度下关断功率MOS管,实现过温保护功能.恒流驱动模块采用比例电流采样方式,在电源电压正负变化10%范围内,驱动电流变化小于4.3%,温度传感模块利用PTAT(与绝对温度成正比)电压与基准电压比较,产生关断信号,关断温度在50℃-125℃范围内可由外接电阻设定.该芯片实现了温度传感模块和白光LED恒流驱动模块的单片集成,在LED照明技术中有一定的应用价值.     

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。