Emerging Practice in a Digital Age: A guide to technology-enhanced institutional innovation

Since the launch of the JISC guide Innovative Practice with e-Learning (JISC, 2005), so much has changed. At that time, early adopters were exploring the potential of mobile and wireless learning. Since then, the increased availability of public and institutional wireless networks, the emergence of new and more powerful technologies and an increase in personal ownership of these technologies are changing the way we connect, communicate and collaborate. Emerging Practice in a Digital Age, one of a series of Effective Practice guides, draws on recent JISC reports and case studies and looks at how colleges and universities are continuing to embrace innovation and respond to changes in economic, social and technological circumstances in a fastchanging world.

Determinação de posicionamento de nós roteadores em redes sem fio utilizando redes imunológicas.

A tecnologia sem fio (wireless) vem tomando conta do mundo. A cada dia mais pessoas estão trocando seus equipamentos com fio por equipamentos com a tecnologia wireless. Isso vem crescendo, devido as suas vantagens, tais como: facilidade de instalação e manutenção, redução de tempo de instalação de dispositivos, inexistência de estrutura de cabeamento, economia no custo de projetos, economia em infraestrutura, flexibilidade de configuração de dispositivos, economia no custo de montagem, flexibilidade na alteração de arquiteturas existentes e outros. Por essas facilidades supracitadas a área de automação industrial está também aumentando o seu interesse nessa tecnologia wireless. Nessa área, a segurança, confiabilidade e robustez dos dados são de suma importância. Então, para minimizar os efeitos das interferências geradas nesse meio são usadas técnicas de espalhamento em frequência e topologia em malha ou árvore para transmissão dos dados enviados pelos sensores aos nós roteadores até chegar ao gateway. Sendo assim, o posicionamento dos nós roteadores na rede em malha garantirá a menor influência dessas interferências. Esse trabalho propõe uma ferramenta de posicionamento de nós roteadores intermediários, chamado POSIMNET (Positioning Immune Network Rede Imunológica de Posicionamento), que auxilia o projetista da rede de automação industrial a encontrar a melhor configuração da rede sem fio. O POSIMNET é baseado nas redes imunológicas artificiais, que propõe criar n caminhos quaisquer ou disjuntos para as informações enviadas pelos nós sensores chegarem ao gateway, através da supressão, clonagem e reconfiguração de nós roteadores intermediários. Além disso, o algoritmo também é capaz de atender os critérios de baixo grau de falha e baixo número de retransmissão pelos roteadores. Esses critérios podem ser habilitados individualmente ou combinados com pesos iguais ou diferentes para cada um, a critério do usuário. A ferramenta POSIMNET é formada por dois módulos: (i) Rede Imunológica agrega elementos de dois modelos de redes imunológicas (SSAIS e AiNet); (ii) Campos Potenciais - posiciona os nós roteadores pelos campos potenciais, onde os sensores críticos os atraem enquanto que os obstáculos e outros roteadores os repelem.

Flexible electronics: The next ubiquitous platform

Thin-film electronics in its myriad forms has underpinned much of the technological innovation in the fields of displays, sensors, and energy conversion over the past four decades. This technology also forms the basis of flexible electronics. Here we review the current status of flexible electronics and attempt to predict the future promise of these pervading technologies in healthcare, environmental monitoring, displays and human-machine interactivity, energy conversion, management and storage, and communication and wireless networks. © 2012 IEEE.

无线多跳网中具有网络编码意识的机会路由协议

针对现有COPE协议消极编码的问题,提出一种具有网络编码意识的机会路由协议NCAOR。该协议兼取机会路由和网络编码的优势实现高效地报文投递。在每一跳转发时,节点均选取多个冗余邻居节点构成机会节点集协助数据发送。收到报文后,机会节点利用局部拓扑知识和侦听的邻居报文接收信息判断转发报文的网络编码机会,并通过综合路径距离和编码收益的效用函数评估报文转发效能,智能设置转发响应时间。仿真结果表明,该协议相对采用最短路径路由的COPE方案具有网络吞吐量大、能耗低和节点编码机会更多的优点。

WIA建筑能耗测量与优化运行系统

在分析建筑高能耗原因的基础上,提出了一个基于WIA的建筑能耗测量与优化运行方案,详细介绍了该方案的结构组成和原理。

基于工业无线网络WIA技术的储油罐监测系统

在分析现有的储油罐区监测技术的基础上,提出了一个基于工业无线网络WIA技术的储油罐监测系统方案,详细介绍了该方案的系统运行原理、系统结构及系统功能。

基于工业无线网络WIA技术的管道泄漏监测系统

在分析现有的管道泄漏监测技术的基础上,提出了一个基于工业无线网络WIA技术的管道泄漏监测系统方案,详细介绍了该方案的系统运行原理、系统结构及系统性能及特点。

短程及多跳的工业无线网络实时性和可靠性研究

无线通信技术极大地推动了科技发展和社会进步，已成为国际技术竞争的焦点和制高点之一。其中工业环境下无线网络技术的开发和应用，成为继模拟仪表控制系统、集散控制系统、现场总线控制系统之后，在过程控制和工业自动化领域拥有广阔市场前景的应用技术。随着无线通信技术的进一步发展，在未来的工业过程自动化领域，无线网络技术将会有更为广阔的应用前景。 工业无线网络技术的发展所面临的主要问题是：如何保证工业通信过程中的实时性和可靠性。本论文较为详尽地研究、探讨了工业无线网络中的实时性和可靠性问题，阐述了实时性和可靠性的涵义，分析了工业无线网络对实时性和可靠性的特殊需求，在借鉴已有研究成果并进行创新的基础上提出了问题解决方案。本文重点在网络的数据链路层和网络层展开了研究工作。主要的研究内容与创新点包括以下几个方面： 在数据链路层的媒体访问控制层，针对恶劣的工业环境对数据传输的实时性和可靠性的较高要求，和以往工业无线网络中采用的无线通信技术，如无线局域网、蓝牙和Zigbee等技术存在抗干扰能力差的严重缺陷的现实，本论文采用目前无线通信技术领域的热点技术——超宽带技术作为物理信道的通信介质，在对超宽带技术的特点和工业无线信道模型进行研究的基础上，充分利用超宽带技术抗干扰能力强的特点，采用跨层设计的思想——物理层和媒体访问控制层联合设计的方式，提出了基于信道状态的信道选择和速率自适应的多信道媒体访问控制协议，该协议一方面根据射频环境的动态变化，使用信道估计技术从多个可选数据信道中，选择可用的或者相对理想的信道用于数据的传输；另一方面在传输过程中，根据物理信道反馈的误码率值来判断当前的通信质量，可以要求物理层执行参数修改策略，实现发射速率的调整，解决由于多用户干扰、碰撞和工业环境干扰等因素造成的误码率增大问题，来满足工业无线网络的实时性和可靠性需求。该协议优于目前已有的协议，可以缓解干扰带来的延迟增大和吞吐量下降的问题，更好地满足工业通信的实时性和可靠性需求。 在数据链路层的逻辑链路控制子层，针对已有的无线网络缓存管理策略在通信中发生拥塞时，无法提供对实时数据的实时性保证，以及不适当的报文丢弃机制无法提供对非实时数据提供可靠性保证的问题，本文借鉴有线通信网络中缓存队列数据分组的动态概率丢弃思想，提出了一种适用于工业实时数据通信的超时早期检测机制，其基本思想在于节点的缓存队列在接纳新到的实时数据时，对其能否在规定的时延限制之内到达目的节点进行估计，并根据估计结果进行早期丢弃，防止无效的传输占用宝贵的无线资源；建立分别存储实时数据和非实时数据的双队列缓存管理策略，两类队列采用循环调度的方法实现数据传输的公平性，以保证数据传输的实时性和可靠性。本文提出的节点缓存管理策略有利于减小排队时延、降低后继分组超时丢弃和缓存队列拥塞发生的概率，与已有的无线网络缓存管理策略相比，可以提高实时数据传输的实时性和非实时数据传输的可靠性。 在网络层，本文重点在路由协议方面进行了研究，针对已有路由协议在工业无线网络应用中存在的不适用性问题，以及工业无线网络传输路径可靠性较差的特点，本文采用可靠性理论，对不相交和相交的多路径选择策略的可靠度进行了分析；针对工业无线网络对通信的可靠性和实时性的特殊需求，本文提出了路径可靠性评估模型。在对基于节点的邻居列表链路稳定性预测的基础上，通过路径的可靠性因子和延时因子的计算来建立可靠的多路径路由。在模拟了不稳定和不可预测的工业通信现场环境后，通过与传统的单路径路由协议和多路径路由协议性能的对比，验证了本文提出的多路径路由协议的有效性。在不稳定和不可预测的通信环境下，其可靠性和实时性性能优于已有的同类多路径路由协议。 针对已有无线网络路由协议由于对节点故障类型分析不充分，使得网络中的关键节点更新和路由重构次数增加，从而造成工业无线网络的可靠性和实时性难以得到满足的问题，本文借鉴D.Pradhan在经典理论文献中提出的系统可靠性性能改进的思想，根据工业无线网络的工作环境和特点，研究了分簇结构的工业无线网络中的关键节点——簇首节点的容错算法。本文根据对网络中簇首节点的故障类型的分类，提出了能够及时判断故障类型和有效解决相应故障的簇首容错算法，进而保证在簇首发生故障的情况下，使其能够得到及时的检测和恢复，从而满足工业无线网络的可靠性和实时性需求。本文提出的簇首容错算法在网络中的簇首节点发生故障或通信链路出现异常情况时，能够有效地提高数据发送和接收效率，降低通信延迟，其可靠性和实时性明显优于无容错机制的路由协议算法和已有节点容错机制的路由协议算法，因此本文提出的簇首容错算法更适用于环境恶劣的工业现场环境。

Asynchronous Auction for Distributed Nonlinear Resource Allocation Problem

Resource Allocation Problems (RAPs) are concerned with the optimal allocation of resources to tasks. Problems in fields such as search theory, statistics, finance, economics, logistics, sensor & wireless networks fit this formulation. In literature, several centralized/synchronous algorithms have been proposed including recently proposed auction algorithm, RAP Auction. Here we present asynchronous implementation of RAP Auction for distributed RAPs.

AIDA-Based Real-Time Fault-Tolerant Broadcast Disks

The proliferation of mobile computers and wireless networks requires the design of future distributed real-time applications to recognize and deal with the significant asymmetry between downstream and upstream communication capacities, and the significant disparity between server and client storage capacities. Recent research work proposed the use of Broadcast Disks as a scalable mechanism to deal with this problem. In this paper, we propose a new broadcast disks protocol, based on our Adaptive Information Dispersal Algorithm (AIDA). Our protocol is different from previous broadcast disks protocols in that it improves communication timeliness, fault-tolerance, and security, while allowing for a finer control of multiplexing of prioritized data (broadcast frequencies). We start with a general introduction of broadcast disks. Next, we propose broadcast disk organizations that are suitable for real-time applications. Next, we present AIDA and show its fault-tolerance and security properties. We conclude the paper with the description and analysis of AIDA-based broadcast disks organizations that achieve both timeliness and fault-tolerance, while preserving downstream communication capacity.

Open Issues on TCP for Mobile Computing

We discuss the design principles of TCP within the context of heterogeneous wired/wireless networks and mobile networking. We identify three shortcomings in TCP's behavior: (i) the protocol's error detection mechanism, which does not distinguish different types of errors and thus does not suffice for heterogeneous wired/wireless environments, (ii) the error recovery, which is not responsive to the distinctive characteristics of wireless networks such as transient or burst errors due to handoffs and fading channels, and (iii) the protocol strategy, which does not control the tradeoff between performance measures such as goodput and energy consumption, and often entails a wasteful effort of retransmission and energy expenditure. We discuss a solution-framework based on selected research proposals and the associated evaluation criteria for the suggested modifications. We highlight an important angle that did not attract the required attention so far: the need for new performance metrics, appropriate for evaluating the impact of protocol strategies on battery-powered devices.

Design and Analysis of an Independent, Layer 2, Open-Access WiFi Monitoring Infrastructure in the Wild

While WiFi monitoring networks have been deployed in previous research, to date none have assessed live network data from an open access, public environment. In this paper we describe the construction of a replicable, independent WLAN monitoring system and address some of the challenges in analysing the resultant traffic. Analysis of traffic from the system demonstrates that basic traffic information from open-access networks varies over time (temporal inconsistency). The results also show that arbitrary selection of Request-Reply intervals can have a significant effect on Probe and Association frame exchange calculations, which can impact on the ability to detect flooding attacks.

Adaptive Measurement-Based Policy-Driven QoS Management with Fuzzy-Rule-based Resource Allocation

Fixed and wireless networks are increasingly converging towards common connectivity with IP-based core networks. Providing effective end-to-end resource and QoS management in such complex heterogeneous converged network scenarios requires unified, adaptive and scalable solutions to integrate and co-ordinate diverse QoS mechanisms of different access technologies with IP-based QoS. Policy-Based Network Management (PBNM) is one approach that could be employed to address this challenge. Hence, a policy-based framework for end-to-end QoS management in converged networks, CNQF (Converged Networks QoS Management Framework) has been proposed within our project. In this paper, the CNQF architecture, a Java implementation of its prototype and experimental validation of key elements are discussed. We then present a fuzzy-based CNQF resource management approach and study the performance of our implementation with real traffic flows on an experimental testbed. The results demonstrate the efficacy of our resource-adaptive approach for practical PBNM systems