电力线载波抄表系统的负载均衡算法研究

为提高电力线载波通信系统的可靠性和性能,论述了远程抄表系统的架构和特点,分析了路由算法研究的必要性,提出了基于遗传算法的负载均衡路由算法.该算法通过网络节点变化、拓扑结构动态优化目标并自动组网.仿真与试验结果表明,该算法能为电力线载波远程抄表系统提供有效的自动组网方式,保证系统通信的负载均衡,与传统编号顺序查询路由方式相比,减小网络延迟性达20%以上,提高网络联通性超过15%.     

电力线载波通信中继策略

介绍了采用低压电力线载波通信技术的城市路灯智能监控系统.由电力线信道环境的特殊性所导致电力线载波通信的可靠性低和通信距离短等不足的特点,结合路灯分布的结构,提出一种独特的中继策略.该中继策略可以根据信道质量的变化动态地建立、维护、优化电力线通信网络路由,保证通信网络的有效性.文中阐述了中继策略的实现过程.实验表明,该方法可自适应地选择合适的中继节点,实现电力载波信号在电力线上的传输更加可靠、有效.该系统投入运行后稳定可靠,具有良好的应用和推广价值.     

基于电力线载波的抽油机井巡回监测系统

本文介绍了电力线载波基础上的网络化、分布式抽油机井巡回监测系统,给出了各测试节点的硬件组成和系统监测管理平台,制定了通讯协议并介绍了系统远程硬件复位功能的实现。     

自动抄表系统中电能表的设计

自动抄表系统是电力部门实现自动化的组成部分,电能表又是该系统中重要的终端设备.利用电量计量技术、嵌入式控制技术、电力线载波通信技术和红外通信技术,完成了多功能电能表的设计.该电能表计量准确,具有远程抄表和近距离红外抄表功能,在结构上兼顾多种电力线载波方式,便于选择不同载波方式来实现远程通信,提高了不同通信方式下电能表的...     

基于免疫－蚁群算法的电力线载波抄表动态路由方法

针对低压电力线载波抄表系统中现有的中继路由算法的不足,提出了一种基于免疫-蚁群算法的低压电力线载波抄表动态路由方法。免疫算法把目标函数和约束条件作为抗原,目标函数的优化解对应为抗体,利用蚁群算法产生和更新抗体,抗体的交叉操作及其对与抗原具有高亲和力的抗体的记忆,均能促进快速求解。该算法结合了人工免疫算法与蚁群算法两者的优点。通过仿真实验验证该算法的收敛性、抗毁性和运算性能,算法能够根据低压电力线信道的变化情况以相对较少的迭代次数收敛到最优路径,提高整个低压电力线载波抄表系统的时效性。     

基于图论生成树的低压电力线通信路由方法

电力线信道的阻抗特性、信号衰减特性及噪声特性导致电力线通信的可靠性成为制约其广泛应用的重要因素。分析了低压配电网的物理拓扑结构和逻辑拓扑结构,结合我国低压集中抄表系统应用的工程特点,提出了一种基于图论生成树的电力线通信自动路由方法。该方法能够有效地建立起电力线通信网络路由,并根据信道变化动态地维护路由,保证了电力线网络的可靠性。实验测试表明了该路由方法的有效性、可靠性和实用性。     

基于μC/OS-II的电力线载波抄表系统集中器

低压电力线载波远程抄表技术是一项有广泛应用前景的新技术。介绍了一种基于μC/OS-II的电力线载波抄表系统集中器,包括整个远程抄表系统的结构,集中器的功能和软硬件设计。该集中器在现场经过了测试实践,达到了预期目标。     

一种远程电流数据采集系统的设计

为了解决电流数据采集系统中的远程传输问题,提出了一种利用半导体磁阻式电流传感器（MRCS）和电力载波芯片LM1893实现的设计;系统硬件主要由AT89C2051单片机主控单元、数据采集单元、LM1893 电力载波发送单元等三部分组成;系统软件以MCS-51汇编语言编制,并给出了软件设计的流程图;由于采用了电力线载波技术,该系统适用于远距离信号的测量和传输,具有较高的实用价值.     

基于PLC技术的嵌入式视频监控系统设计

随着电力线载波通信技术的发展,基于低压电力线的数据传输速率不断提高,越来越多的人开始关注其应用.提出并设计了一种基于低压电力线载波通信的嵌入式视频监控系统.系统采用ARM+Linux作为视频采集、压缩的软硬件平台,通过由INT5200构成的电力线载波模块与电网相连,并利用电力网络传输实现视频监控系统的网络化管理.实践证明该方案具有一定的可行性,系统能够独立完成视频数据的采集、压缩与传输功能,且在较好的电力环境下效果理想.     

基于μC/OS-Ⅱ的电力线载波抄表系统集中器

低压电力线载波远程抄表技术是一项有广泛应用前景的新技术。介绍了一种基于μC／OS-Ⅱ的电力线载波抄表系统集中器,包括整个远程抄表系统的结构,集中器的功能和软硬件设计。该集中器在现场经过了测试实践,达到了预期目标。     

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.     

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~~     

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