移动Ad Hoc网络的入侵检测研究

移动Ad Hoc网络是一种特殊的移动网络。目前的入侵检测技术不再适用于这种新的环境。本文在分析Ad Hoc网络的特点和当前的入侵检测技术后,给出了一种适合于Ad Hoc网络的入侵检测系统的结构。     

移动Ad Hoc网络信任管理综述

移动Ad Hoc网络是由移动节点组成的无线移动通信网络,具有动态拓扑、无线通信的特点,易受到各种安全威胁。信任管理为实体间的相互信任问题提供了决策框架,是移动Ad Hoc网络安全方案的基础。综合分析了移动Ad Hoc网络信任管理研究的最新进展。首先介绍了移动Ad Hoc网络中信任关系的特点及信任管理的分类,然后对每个类型的一些典型信任管理方案进行了分类论述和综合比较,最后指出了下一步研究中应当着重考虑的问题。     

基于多协议标签交换技术的Ad Hoc网络研究

将MPLS(Multiprotocol Label Switching)技术引入到Ad Hoc网络中,目的是为Ad Hoc网络提供快速转发能力、QoS功能和可扩展性。针对传统IP转发机制在移动自组网（Ad Hoc）中的缺陷,研究了基于MPLS技术的Ad Hoc网络,详细描述了其基本结构,并提出了新的在Ad Hoc网络中支持自愈恢复的MPLS信令协议DMSP（Dynamic MPLS Signaling Protocol）,最后通过仿真实验对DMSP的自愈恢复方式进行了性能分析。     

Exploring problem solving patterns and their impact on learning achievement in a blended learning environment

Blended learning, thoughtfully combining the best elements of online and face-to-face education, is likely to emerge as the predominant teaching model of the future. In this paper, we present a blended learning environment combining mobile learning, web-based learning, and classroom teaching to provide realistic, practical opportunities for learners and teachers to engage in problem solving activities. The purpose of this study was to explore problem solving patterns and their impact on learning achievement in a blended learning environment. Through quasi-experimental instruction, we collected all of the data of the learning processes from 34 students in a blended learning environment using classroom instruction, mobile and web scenarios. By combining cluster analysis and content analysis, we were able to identify three groups with distinct characteristics: the hybrid-oriented group, the technology-oriented group, and the efficiency-oriented group. Learners in the hybrid-oriented group used the classroom, mobile and web scenario almost equally. They displayed a regular manner in following the instructor’s teaching procedure, and tended to passively accept whatever the teacher said. Students in the technology-oriented group spent most of their time using mobile and web technologies but they revealed superficial problem solving abilities such as a lack of understanding and planning. The efficiency-oriented group was characterized by the efficient monitoring of learning processes. It was more task-oriented and performed better than the other two groups.     

一种基于签密的移动自组网络身份认证方案

移动自组网是一种有特殊用途的对等式网络,具有无中心、自组织、可快速展开、可移动等特点,这些特点使得它在战场、救灾等特殊场合的应用日渐受到人们的重视。对移动自组织网络节点间的认证技术进行了研究。分析了目前移动自组网络中适用的认证协议和方法,提出一种基于签密的无线Ad Hoc网络身份认证方案。通过分析证明,该方案在无线Ad Hoc网络环境中有较高的安全性。     

A cloud-based learning environment for developing student reflection abilities

Students learn new knowledge effectively through relevant reflection. Reflection affects how students interact with learning materials. Studies have found that good reflection abilities allow students to attain better learning motivation, comprehension, and performance. Thus, it is important to help students develop and strengthen their reflection abilities as this can enable them to engage learning materials in a meaningful manner. Face-to-face dialectical conversations are often used by instructors to facilitate student reflection. However, such conventional reflection methods are usually only usable in classroom environments, and could not be adopted for distance learning or after class. Cloud computing could be used to solve this issue. Instructor guidance and prompting for initiating reflection could be seamlessly delivered to the students’ digital devices via cloud services. Thus, instructors would be able to facilitate student reflective activities even when outside the classroom. To achieve this objective, this study proposed a cloud-based reflective learning environment to assist instructors and students in developing and strengthening reflection ability during and after actual class sessions. An additional experiment was conducted to evaluate the effectiveness of the proposed approach in an industrial course. Results show that the learning environment developed by this study is able to effectively facilitate student reflection abilities and enhance their learning motivation.     

几种Ad Hoc网络组播路由协议的分析与比较

Ad Hoc网络是一种不依赖于固定设施的,自组织的无线网络,其组网快捷、方便,具有广阔的发展前景.在典型的Ad Hoc网络应用中,网络主机通过按组工作来完成一项特定的任务.因此,组播在Ad Hoc网络中是一个十分重要的功能.按照参与组播路由的结点构成的网络拓扑结构的不同,分别介绍了基于树的组播路由协议AMRIS,基于格网的组播路由协议ODMRP、CAMP、FGMP,和基于混合的组播路由协议AMRoute,并对它们各自的工作方式进行了分析,最后对它们各自的特点进行了比较.     

基于NS2的Ad Hoc网络路由协议性能对比分析

移动Ad Hoc网络是移动节点动态临时组建的自组织网络,路由协议一直都是Ad Hoc网络研究的关键问题。使用NS2网络仿真软件,在不同的场景下分析比较移动Ad Hoc网络的5种路由协议DSDV、OLSR、DSR、AODV和TORA性能,得出不同路由协议在不同场景下的优缺点和适用的网络环境。     

Ad Hoc中的一种新型分簇算法及性能仿真

简要介绍了已有的分簇算法,并讨论了这些算法的优缺点.针对这些算法的不足,提出了一种新型有效、适用于大规模高速运动Ad Hoc网络的分簇算法.仿真实验证明该算法可有效解决均匀分簇、均衡结点负担、保持簇结构的稳定性等问题,并能够满足大规模高速运动Ad Hoc网络的要求.给出了相关的仿真分析和结论.     

移动自组网多路径QoS路由协议

多路径路由能有效地增加网络的吞吐量以及平衡网络负载,结合移动自组网特点,提出了一种适合移动自组网的多路径QoS路由协议,该协议使用“软状态”方式进行资源预留,并在路由维护过程中使用了局部重构技术,有效地降低了协议的路由开销。模拟结果进一步表明,在动态的网络环境下,该多路径QoS协议能够有效地实现网络负载均衡,提高网络资源利用率,为移动自组网提供可靠而高效的传输性能。     

移动Ad Hoc网络路由修复算法研究

针对移动Ad Hoc网络路由算法本地修复方面,研究移动Ad Hoe网络由于节点相对运动或无线环境变化所引起的链路失效的修复问题.分析传统的本地修复方式采用全网泛洪所产生的大量控制开销对业务传输时延及分组成功交付率等方面产生的影响.采用基于on-the-fly策略的移动Ad Hoc网络路由修复算法研究,构造了将修复请求区域限制在两跳范围内的修复模型,并建立相应的修复函数,从而实现在满足修复概率的前提下降低网络泛洪与控制开销的目标.     

Could a mobile‐assisted learning system support flipped classrooms for classical Chinese learning?

In this study, the researcher aimed to develop a mobile‐assisted learning system and to investigate whether it could promote teenage learners' classical Chinese learning through the flipped classroom approach. The researcher first proposed the structure of the Cross‐device Mobile‐Assisted Classical Chinese (CMACC) system according to the pilot survey and reviewed literature, and then adopted a quasi‐experimental design to understand whether the developed system could promote and support flipped classroom learning for classical Chinese. A total of 56 eleventh graders from two classes participated in the experiment. The learners in the experimental group learned classical Chinese with the flipped classroom learning strategy with the assistance of the CMACC system, while the control group adopted the flipped classroom learning strategy without using the CMACC system. The results reveal that all of the students improved their Chinese performance, but it was noticeable that the learners who used the CMACC system showed better motivation in terms of self‐directed preview learning, while those who only learned with the traditional textbooks tended to be more passive. In sum, the mobile‐assisted learning system added value in providing learners with opportunities to achieve anytime and anywhere flipped classroom learning. The integration of ubiquitous mobile learning technology and the flipped classroom strategy can be viewed as a critical factor leading to students achieving self‐regulated learning. It is also suggested that instructors should carefully take the targeted learners' cultural background and the availability of supporting learning devices into consideration so as to prevent the flipped classroom from exacerbating the digital divide. Other suggestions for educators and instructional designers are also proposed.     

Ad Hoc网络安全

Ad Hoc网络是针对移动主机提出的一种新型无线网络范例，与传统的移动无线网络不同，它不依赖任何固定设备。设计这种网络的一项主要挑战就是抵抗攻击的脆弱性。在这篇文章中，我们主要研究Ad Hoc网络所面临的威胁以及要达到的安全目标。我们找出这种新型网络环境下面临的新的挑战，并设计出新的方法以保证网络的正常通信。进一步地说，我们利用Ad Hoc网络内在的冗余(节点之间存在多条路线)来防止攻击。     

基于高速以太网的Ad Hoc网络的测试仿真系统

针对移动Ad Hoc网络路由协议调试的重要性和困难性，设计了一个动态的测试仿真系统。通过采取分布式的体系结构，虚拟传输的方法，该系统建立了真实的大规模移动Ad Hoc网络测试环境，可以在上面仿真测试设计的网络层和更上层的协议。同时，系统也解决了隐藏节点和暴露节点问题。     

基于Mashup的移动学习平台

Mashup是Web2.0中一种重要的特性,它能够对现有的数据和服务进行整合,提升数据的价值。本文基于Mashup技术构建一个学习平台,讨论该平台的组成模块、总体架构和系统特性。利用该平台和移动终端的有效结合,建立了一个实时的课堂反馈的应用模式,并在课堂实践中进行检验。结果表明这种方式可以有效地提升学生的积极性和学习效率。最后指出后续的相关研究方向。     

自组网分簇算法仿真设计

自组网是一种由移动节点自组织形成的、不需要任何基础设施的网络,针对其随机的拓扑结构研究人员提出了基于分簇结构的拓扑机制,用于网络路由优化和安全控制。然而,这些算法在不同的移动环境中面临着不同的挑战,因而所表现出来的性能也各不相同,为进一步验证这些算法在不同移动环境中的有效性,文中使用Delphi设计了自组网的几个典型分簇算法,通过随机环境的仿真实验,得到相关仿真数据,分析比较了这些算法的性能,为进一步的研究提供依据。     

基于Ad Hoc网络Anycast机制的应用与研究

针对Ad Hoc网络和Anyeast技术特点以及Anycast机制在AdHoc环境下的优点，构想出基于Ad Hoc网络下Anycast机制的应用场景，提出适合基于自组织网络的Anycast服务的可行性方案的一些设想。在Ad Hoc环境下，探讨了网络层和应用层的Anycast机制的实现方法。     

大规模移动自组网安全群组通信研究

移动自组网中的安全群组通信需要处理群组成员关系的动态性、成员位置的动态性、以及网络分区和合并等情况。如何高效地处理这些情况是移动自组网安全群组通信中要解决的重要问题。针对成员关系动态性、成员位置动态性和网络分区和合并带来的问题，提出研究与设计一种移动自组网中的“虚拟动态骨干网”模型。主要从组成员认证和组密钥管理两方面进行了研究，并基于虚拟动态骨干网提出了初步的解决方案。     

移动Ad Hoc网络DSR路由协议性能分析

无线移动Ad Hoc自组网是由不依赖任何已有的网络设施的移动节点组成,该网络可以通过节点路由发现机制转发分组,并进行路由维护.Ad Hoc网络路由协议中DSR路由协议在不同发包率和节点移动速率的情况下各项网络性能都优于其他路由协议,尤其当网络业务量不大时性能更优.基于路由缓存大小和路由更新时间对协议性能的影响,利用OPNET建立DSR路由协议的Ad Hoc网络,并对路由出错、路由开销和时延等关键参数的仿真统计.仿真结果与理论分析一致,一般地,随着路由缓存变大和路由更新时间变短,网络中路由出错、路由开销和时延性能都有所提高.     

无线AdHoc网络中AODV路由算法的研究与改进

无线AdHoc网络是一个多跳的、临时的、对等的自治系统,它由一组带有无线收发信装置的移动节点组成。由于在军事通信、紧急救援、传感器网络等通信场合的广泛应用,无线AdHoe网络成为当前研究的热点之一。针对无线AdHoc网络中AODV路由协议算法在网络拓扑结构改变后出现的性能缺陷,提出了一种改进后的AODV路由协议M—EAODV,通过设置多条备份路由来减少链路修复。仿真结果表明,改进后的AODV在分纽传送成功率、平均端到端时延、路由开销等性能方面都得到了有效改善,能够在链路中断后迅速启用备份路由,更适应于拓扑结构变化快的网络环境。