一种FlexRay总线优化方法研究

为了提高FlexRay车载网络带宽利用率,减小消息帧的最坏响应时间,对FlexRay总线配置问题进行研究。针对FlexRay协议中静态段负载长度相等,静态消息的长度不等的情况,找到最优静态段负载长度,提高带宽利用率。基于静态段的优化之上,综合分析静态段、动态段消息的最坏响应时间,得到最优总线周期长度。实验结果表明,在得到最优负载的条件下,带宽利用率提高22%,并且在周期长度为982μs时,总线消息帧的最坏响应时间最小,保证了消息传输的实时性、可靠性。     

FlexRay总线静态段消息重传调度策略

FlexRay总线协议具有较强的错误检测机制,但缺少相应的重传机制,对于功能安全需求较高的应用,通信系统难以达到相应的安全等级要求。为此,提出一种静态段消息重传调度策略。该策略以满足全局可靠性目标为前提,减小静态段报文重传对带宽的占用,建立消息重传次数最优化数学模型,对所有消息通过消息传输总延迟时间最小化为目的建立混合整数线性规划数学模型来分配相应的发送时隙及周期。运用建模语言AMPl及相关求解器对上述2个数学模型进行编程求解,并将消息重传调度策略应用于汽车线控系统。实验结果表明,该调度策略在使通信系统满足相应功能汽车安全需求等级的前提下,提高FlexRay总线带宽利用率和消息调度的成功率,同时实现各消息发送时延最小化。     

FlexRay通信协议的总线周期优化

FlexRay是一种具有高带宽、确定性和可靠性的车载网络通信协议,能够满足未来先进汽车高速控制的需要。为了更好地在汽车上使用FlexRay总线协议,根据特定的应用场合,对总线上消息的时间分析和总线周期的优化配置十分重要。对FlexRay周期调度进行了研究,基于二维装箱法和NSGA-II算法提出对在静态段和动态段传输的FlexRay消息进行时间分析的方法,最后将其整合成一个总线优化配置算法。通过优化算法对FlexRay总线周期进行配置,显著提高了 FlexRay总线的带宽利用率,在实际应用中增强了系统的时间     

FlexRay总线技术在航天领域的应用

针对航天领域的CAN 总线技术,本文提出一种新的FlexRay 总线通信方式,并介绍了一种基于FPGA+ FlexRay 架构的处理模式,同时描述了FlexRay 总线的特点和工作原理,从协议上分析了FlexRay 总线在航天领域应用的可行 性,从芯片选用、原理设计、接口实现以及软件设计等方面阐述了FlexRay 总线在我国航天领域的应用。     

新型总线FlexRay网络通信设计实现

随着汽车对通信速率的要求越来越高,FlexRay的应用成为必然趋势。主要介绍新型总线FlexRay的协议、FlexRay网络的系统设计以及FlexRay节点的硬件设计和软件设计。该篇中的FlexRay网络是以集成通信控制器的MPC5567主芯片和收发器TJA1080所构成的节点按点对点拓扑结构来组成的网络,并且以按钮控制灯的开关为实例来介绍FlexRay如何实现网络中各个节点之间的同步和数据收发,从而实现FlexRay网络之间的通信。     

FPGA的1553B总线全消息处理远程终端设计

本文在研究MIL-STD-1553B总线远程终端协议逻辑的基础上,为实现10种消息类型的全部识别处理,采用消息识别的设计方法将总线通信的消息归纳为接收消息、发送消息和地址无效消息3类,并针对每类消息按照细分的消息类型分别处理,基于FPGA技术和有限状态机技术设计实现具有参数可配置的远程终端协议模块.软硬件仿真测试结果表明,本文设计的远程终端协议模块满足MIL-STD-1553B总线远程终端协议功能需求,具有工程可实现性并能与某1553B仿真卡建立总线通信,为设计开发其专用协议产品提供一定技术参考.     

FPGA的1553B总线全消息处理远程终端设计

本文在研究MIL-STD-1553B总线远程终端协议逻辑的基础上,为实现10种消息类型的全部识别处理,采用消息识别的设计方法将总线通信的消息归纳为接收消息、发送消息和地址无效消息3类,并针对每类消息按照细分的消息类型分别处理,基于FPGA技术和有限状态机技术设计实现具有参数可配置的远程终端协议模块.软硬件仿真测试结果表明,本文设计的远程终端协议模块满足MIL-STD-1553B总线远程终端协议功能需求,具有工程可实现性并能与某1553B仿真卡建立总线通信,为设计开发其专用协议产品提供一定技术参考.     

FlexRay静态段消息调度优化研究

为提高FlexRay网络的静态段带宽利用率,对基于时隙复用的FlexRay静态段进行优化研究。将传输的信号编码成消息帧,把编码问题转换为数学意义上的带约束装箱问题,将发送周期呈倍数关系的信号封装成一个消息帧,并运用BFD算法求解。之后基于封装的消息帧,提出一种调度方法使静态段带宽利用率最大化和帧ID数目最小化。最后在FlexRay底盘综合控制系统上验证该方法。结果证明,该算法使带宽利用率提升了18.7%,将每个通信周期内所占的FID个数降低了90.47%,并且把循环周期内静态时隙利用率提升了41.52%。     

一种FlexRay总线通讯测试系统设计

FlexRay总线作为一种高速、灵活、可靠的串行通信总线,已逐渐成为汽车网络的主流。为了验证该总线技术在航天技术应用上的可行性,设计了一个基于TMS570LS3137安全控制器和PXI8517集成测试板卡的FlexRay总线网络测试系统。从硬件设计、平台搭建、协议规范、节点设计、网络定义等方面介绍了测试系统的设计方案,实现了网络中各个节点之间的同步和数据收发,最终实现了FlexRay网络之间的通信。试验结果表明了FlexRay网络通信系统的可行性和可靠性,并以其高速和强冗余特点成功应用于国家863项目机电作动系统研制项目中。     

运用马尔科夫过程分析FlexRay的动态段实时性

作为新一代的车载总线,FlexRay为满足高安全性和可靠性的需求,实时性越来越重要。其基于时分多址（TDMA）静态段发送消息的延时相对稳定,因而对延时震荡较大,基于柔性时分多址（FTDMA）的动态段进行实时性分析,依据静态段的最坏响应延时以及动态段的传输延时,综合运用马尔科夫链分析通信期间的延时情况。通过建立模型进行仿真,验证推导的马尔科夫转移矩阵是正确的。     

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)

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