物理网络拓扑发现算法的研究

局域网交换技术提高了局域网内网格带宽使用的有效性并且部分解决了现有网络带宽问题，在对原有基于SNMP MIB－II的物理网络设备发现算法分析比较的基础上，提出了一种新的算法，用该算法开发的拓扑发现工具能准确地发现物理网络拓扑即子网内交换机到交换机，交换机到路由器，交换机到主机之间的连接关系。     

基于IP网络的物理拓扑自动发现算法

网络管理已成为网络系统运行好坏的关键，而网络拓扑构造的自动发现是进行网络管理、性能分析、故障定位的前提条件．随着网络规模的不断扩大，网络层拓扑结构已经不能准确反映网络设备之间的连接关系．因此，本文依据标准的SNMP和ICMP等协议和相关的MIB信息，提出并证明了以太网设备连接判定定理，并以此为基础提出了一种物理拓扑自动发现算法．与已有的物理拓扑发现算法相比，该算法不要求所有网络设备都支持SNMP协议，具有高效、实用的优点．试验结果显示，该算法能快速、准确地生成IP网络的物理拓扑图．     

局域网环境下安全准入认证方法的研究

在局域网环境中，只要存在物理的连接端口，未经授权的网络设备或用户就可能通过连接到局域网的网络设备自动的进入网络，造成极大的安全隐患。同时，基于端口的VLAN分配缺乏灵活性、不可控的IP存取易造成IP地址冲突等网管问题。这些问题的有效解决，在企业局域网环境中，已显得十分重要。我们通过研究近年来大型局域网身份和授权技术并将其实施在企业局域网中，有效解决上述问题。     

校园网拓扑自动发现系统的设计与实现

本文根据校园网管理的实际情况,结合目前比较流行的拓扑自动发现算法,设计并实现了一个网络拓扑自动发现系统。采用遍历路由表算法实现主域拓扑的自动发现,并通过多线程编程技术提高子网拓扑发现的效率,同时,软件还提供了对网络设备的性能监视功能,极大方便了网络管理人员对网络设备的监控。     

非授权局域网拓扑探测系统的设计与实现

局域网拓扑探测作为网络安全研究的一项重要内容，目前已经很难适应复杂网络环境的需要，存在很多问题亟待解决。在对局域网网络层和物理拓扑探测算法研究的基础上，本文设计并实现了非授权局域网拓扑探测系统Network Probe。该系统以网络层和物理拓扑探测算法为核心，结合了SNMP协议和多种探测方法。测试表明，Network Probe在准准确性、完整性和探测效率等方面能够满足大规模异构局域网拓扑探测的要求。     

自动化运维中网络拓扑发现技术的研究与实现

随着自动化运维过程中越来越复杂的运维场景和紧迫的网络设备统一管理需求,网络设备自动拓扑发现技术的研究在大型企业中变的十分重要。为了准确、快速、完整地进行拓扑发现,根据实际运维需求,在链路层选择了简单网络管理协议（SNMP）和互联网控制报文协议（ICMP）结合拓扑发现,在网络层选择了SNMP协议拓扑发现。设计实现了拓扑发现算法,并在实验中验证了方法的有效性,能够胜任自动化运维中大型网络的拓扑发现。     

基于SNMP协议的网络拓扑发现和显示

提高网络设备和服务管理的智能性和可操作性，对网络中的设备拓扑连接自动准确的发现以及发现结果的可视化具有重大意义。文章介绍了采用SNMP协议对网络中设备拓扑结构进行深度搜索的算法和采用图形化显示的方法。实验结果表明该算法使拓扑发现操作的实时性和真确率都达到了实用要求。     

一种交换式以太网拓扑结构的发现算法

首先介绍了目前局域网拓扑发现的主要方法及存在的问题,然后提出一个基于生成树协议 地址转发表的交换式以太网物理拓扑结构的自动发现算法.算法首先利用生成树协议建立起交换机之间的连接关系,在此基础上进一步利用地址转发表建立起交换机与主机的连接关系.该算法 1)能给发现被生成树协议阻塞的连接;2)通过处理连接冲突,能够准确无误的发现网络物理拓扑结构;3)算法开销小,时间复杂度低.文中算法已成功地应用于社区宽带综合业务网络管理系统(CBISNMS)中.     

基于Web的网络拓扑发现算法研究与实现

随着计算机网络技术的发展，通过不断增加网络设备数量、扩大网络规模来满足日益增长的网络服务需求，致使网络管理尤其是二层设备的管理任务逐渐加重，实现其拓扑结构的自动发现对于现代网络管理变得尤为重要。在分析比较现有二层拓扑结构算法的基础上，结合谷歌开发的GWT技术，实现了基于Web的网络可视化管理，提高了网络服务质量，对网络开发人员和网络管理人员具有较好的参考价值。     

基于SNMP的物理网络拓扑发现的实现

网络拓扑信息对于网络管理是至关重要的。使用简单网络管理协议SNMP可以获取存放在网络设备的管理信息库MIB中的信息。根据MIB中的地址转发表,判断各网络设备之间的端口链接,从而可以得到局域网的网络拓扑结构。实验表明,该过程有效、可用,能够准确发现局域网的拓扑结构。     

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.     

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.     

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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