异步FIFO结构及FPGA设计

首先介绍异步FIFO的概念、应用及其结构，然后分析实现异步FIFO的难点问题及其解决办法；在传统设计的基础上提出一种新颖的电路结构并对其进行综合仿真和FPGA实现。     

一种基于格雷码的异步FIFO设计与实现

介绍了FPGA在实现异步FIFO及其在跨时钟域逻辑设计中的应用，并利用Gray码作异步FIFO指针的方法。该FIFO实现方案与使用传统方案相比，避免了亚稳态的出现，性能更稳定。本设计采用Verilog硬件描述语言实现，具有良好的可移植性和设计灵活性。最后，给出了系统的仿真及综合结果。     

读写数据宽度不同的异步FIFO设计

提出并实现了具有总线功能的异步FIFO,即写入字宽和读出字宽不同的高速异步FIFO设计。此FIFO基于Altera公司的Stratix系列FPGA实现,达到了高于200Mhz的工作频率,采用venlog语言设计,通过对设计进行简单的修改,即可应用于各种不同的系统的设计,给很多带宽不匹配的系统提供了一种简单的解决方案。     

基于Verilog HDL的异步FIFO设计与实现

异步FIFO是一种不同时钟域之间传递数据的常用方法。本文提出一种新颖的异步FIFO设计方案。此方案避免了使用大量的同步寄存器,减小了芯片面积并且提高了工作频率。DC综合的结果表明,用此方法设计的FIFO性能有了显著提高。     

缓冲区结构效率分析

I/O设备与CPU的速度不匹配,制约了计算机系统性能的进一步提高。为此,根据计算机体系结构,对缓冲区结构的效率进行分析,使用EDA计算机辅助设计软件QuartusII设计异步双时钟FIFO缓冲区,并对其进行仿真验证及数据记录,通过对数据的分析,证明系统整体效率与FIFO效率密切相关,只有实现FIFO效率的最大化,才能使系统整体效率最大化,同时FIFO效率最大化也只能在完成系统效率最大化的过程中得以实现。     

异步FIFO中存储单元的分析设计

从异步FIFO的一般结构人手,重点对异步FIFO中的双端口RAM存储器进行了分析,深入研究了存储单元的读写工作原理,以此得出各单元管子参数设计的尺寸要求以及管子单元比(CR),并根据0.35 μm CMOS工艺设计出了1 k×9 bit的异步FIFO,其读取速度约为10 ns.     

异步FIFO中存储单元的分析设计

从异步FIFO的一般结构入手,重点对异步FIFO中的双端口RAM存储器进行了分析,深入研究了存储单元的读写工作原理,以此得出各单元管子参数设计的尺寸要求以及管子单元比(CR),并根据0.35μm CMOS工艺设计出了1k×9bit的异步FIFO,其读取速度约为10ns。     

FPGA异步FIFO设计中的问题与解决办法

通过分析异步FIFO的基本结构和工作原理,以降低亚稳态的出现频率、充分利用异步FIFO的内存资源为主要目的,提出一种在FPGA内部实现的异步FIFO设计方法。本文在传统设计的基础上提出一种新颖的电路结构来准确判断空／满标志位的产生,即检测加计数器的方法;并用QuartusⅡ对其进行仿真,得到了比较好的性能。     

基于FPGA的异步FIFO设计

在现代集成电路设计中,一个系统往往包含了多个时钟,如何在异步时钟间传递数据成为一个很重要的问题,而使用异步FIFO可以有效地解决这个问题。异步FIFO是一种在电子系统中得到广泛应用的器件,文中介绍了一种基于FP-GA的异步FIFO设计方法。使用这种方法可以设计出高速、高可靠的异步FIFO。     

基于加权Gray码及实时状态检测的异步FIFO设计

本文提出了一种新颖的异步FIFO设计，它采用加权Gray码进行指针编码，采用实时的全局状态检测器来控制写／读，是一种高性能的异步FIFO。模拟结果表明，在FIFO深度为4～16的情况下，该设计与已有的FIFO设计相比在性能以及面积开销等方面都获得了明显的改善。该异步FIFO在多核SoC互连设计中具有广泛的应用前景。     

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.     

Call for Papers The 6^th International Conference on Grid and Cooperative Computing

Recent years have seen rapid advances in various grid-related technologies, middleware, and applications. The GCC conference has become one of the largest scientific events worldwide in grid and cooperative computing. The 6th international conference on grid and cooperative computing (GCC2007) Sponsored by China Computer Federation (CCF),Institute of Computing Technology, Chinese Academy of Sciences (ICT) and Xinjiang University ,and in Cooperation with IEEE Computer Soceity ,is to be held from August 16 to 18, 2007 in Urumchi, Xinjiang, China.     

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.     

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.     

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     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to 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     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

正~~