基于USB设备的全数字时钟恢复单元设计

针对通用串行总线(USB)全速设备中的常用时钟恢复方法存在精度差、成本高的问题,设计一种适用于USB全速设备的全数字时钟恢复单元。包含用于从USB总线数据中提取时间信息的模块,以及数字控制振荡器,能够克服因芯片工作条件不同而产生的不良影响。该设计采用全数字电路的设计流程,使用标准单元库进行逻辑综合和布局布线,设计结果满足USB协议要求。     

一种全数字锁相环的设计与应用

介绍一种采用FPGA设计实现的ADPLL的结构及特点,并用该锁相环产生SDH设备的外同步时钟。由于该锁相环的负反馈时钟采用了初始受控分频设计、并采用了合理的环路滤波算法,该ADPLL同传统的数字锁相环(DPLL)一样,在参考源切换过程中输出时钟平滑稳定;同时也和传统的模拟锁相环(APLL)一样,在锁定状态下有稳态相差。对输出时钟的测试表明,该ADPLL产生的SDH外同步输出时钟满足系统的应用要求。     

SDH设备时钟中的数字锁相环设计

提出了一种新的用于实现SDH设备时钟的数字锁相环,采用时数转换器来实现数字锁相环中的鉴相器;该时数转换器的时间测量精度达到200 ps,因而极大地改进了鉴相器的鉴相精度;改进后的数字锁相环具有很好的频率稳定度和相位特性,对时钟源有很好的跟踪能力,且能实现时钟源的平滑切换,完全满足了ITU-T G.813规范要求。     

一款集成HUB的USB设备控制器的设计

介绍了USB设备控制器的基本功能和原理,提出了一款基于6502MCU的通用的带HUB的全速USB设备控制器的体系结构,并完成了整个芯片的设计,而且通过了FPGA验证。这款芯片可以用来开发带HUB的全速USB设备、全速USB设备或全速USBHUB。     

USB1.1设备控制器IP核的设计与实现

针对安全USB设备与PC主机数据通信的需要,依据USB1.1标准规范,文章设计一种USB1.1设备控制器IP核.该控制器IP核支持全速模式下控制、批量、中断三种传输方式,且传输端点数可配置.基于FPGA平台,对控制器IP核进行了实现,并在8051的配合下对实现进行了测试.测试结果表明其与主机之间的数据通信是可行的,可应用于SoC集成设计,为密码安全USB设备的开发奠定了基础.     

一种用于SDH光纤传输系统设备时钟的数字式锁相环

介绍一种用于SDH光纤传输系统设备时钟的数字式锁相环的构成及设计原理,并给出了有关的测试结果,测试结果表明该锁相环具有很好的跟踪特性.     

USB设备控制器的硬件实现与研究

在研究通用串行总线(USB)协议的基础上，建立了数据采样的数学模型，并基于该数学模型提出了数字锁相环的一种简单可靠的实现方法。在给定的USB主机和设备周期差异范围内，该USB设备能够正确传输。在保证带宽利用率的基础上，设计了缓冲区的实现方案，并将该USB设备控制器应用在基于龙芯的SoC芯片上，用FPGA进行了验证。     

低功耗宽调谐范围锁相环设计

针对传统锁相环输出频率范围有限、功耗大的缺陷,通过对压控振荡器震荡机理进行理论分析,设计了一款用于时钟发生器的低功耗、宽调谐范围、低相位噪声锁相环。该锁相环采用了新型可编程、低调谐增益、低功耗的环形振荡器,达到了宽频率输出范围、低相位噪声、低功耗的目的,采用SMIC公司0.18um混合信号工艺,用Cadenced的Hspice仿真工具进行仿真,在1.8V电源电压供电情况下获得了50MHz~1.7GHz的频率锁定范围和1.8mW~2.3mW的较低功耗。单边带相位噪声在10KHz频偏处为-104dBc/Hz.。     

TMS320VC5509A USB设备固件设计与实现

TMS320VC5509A是TI推出的新一代高性能、低功耗数字信号处理芯片,并扩充了当今流行的USB设备接口模块.本文介绍了嵌入式系统USB接口的特点和主要软件模块,分析了TMS320VC5509A USB接口模块的结构,给出了USB设备固件的设计和实现方案.该方案层次清晰,可移植性强,具有广泛的适用性.     

USB2.0设备控制器中工作模式控制电路设计

基于USB2.0协议设计一款USB2.0设备控制器IP核,实现工作模式控制、数据包处理、事务处理、设备枚举控制。介绍了工作模式电路的设计,实现对USB2.0设备的复位检测、高速握手以及工作在全速模式、高速模式、挂起、挂起唤醒情况下的控制。     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

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.     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

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.