一种高效的无线自组网全网可靠广播协议

现有大部分的无线自组网广播协议采用最小虚拟骨干子网进行全网广播,能最小化广播的总发送次数。但是,由于未考虑无线链路的不可靠性,这些协议在实际网络中的广播效率并不高。为此,提出了一种高效的全网可靠广播协议（ENWRB）,该协议采用网络编码技术减少单跳广播的重传次数,并通过一种基于链路感知的虚拟骨干网选择算法产生更高效的广播骨干网。仿真结果表明,在确保所有节点成功接收广播消息的相同前提下,ENWRB协议的效率显著高于HCA(Hierarchical CDS-based Algorithm)协议。     

基于物联网技术平台的O2O商业模式研究

在国家大力推进产业结构调整、信息化的压力下,物联网技术和O2O商业模式作为信息时代的新型生产力,在国内的普及率并不高。本文运用案例分析的方法通过研究大学生创业项目引入O2O商业模式的概念,并与物联网技术有机结合,把握两者之间优势互补的关系,提出两者创新应用,同时从商业模式构成要素的角度对该模式进行系统、深入分析,为中国现代农业信息化建设和结构调整提供了新思路。     

基于无线生理传感器与虚拟现实技术的复愈性环境注意力恢复作用研究

基于卡普兰复愈性环境理论，运用脑机接口设备、智能腕带传感器等无线生理指标检测技术，测试大学生被试人群在沉浸式虚拟现实(VR)情境下，对4种复愈性环境及城市环境在注意力恢复和压力减轻方面的反应及其作用强度，获得被试在不同环境中脑电、心率、肌电的客观生理数据。采用非参数统计方法R语言对数据进行分析。结果显示，多数被试在复愈性环境中较城市环境表现出更好的注意力恢复效果。其中具有逃离性和迷人性特征的自然环境，复愈效果最为明显；在虚拟现实环境中，观赏城市环境图片也具有一定的复愈效果。     

Dually sustainable urban mobility option: Shared-taxi operations with electric vehicles

Electric vehicles (EVs) are energy efficient and often presented as a zero-emission transport mode to achieve long-term decarbonization visions in the transport sector. The implementation of a sustainable transportation environment through EV utilization, however, requires the addressing of certain cost and environmental concerns such as limited driving range and battery-charging issues before its full potential can be realized. Nevertheless, a specific type of use of EVs, namely in taxi services, may elicit positive public opinion, as it promises a commitment toward sustainability in urban life. In light of this, this study proposes an integrated approach that combines EV operation with a conceptual design for shared-ride taxi services. As some productivity loss may be naturally expected due to the time spent in charging, it is important to look at whether such performance loss from the passenger and system standpoints can be offset with ingenuity in operational design. In this study, an EV taxi charge-replenishing scheme that can be coupled with a real-time taxi-dispatch algorithm is designed. The proposed EV charging schemes for taxi services are studied via simulations and the effects of the limited driving range and battery-charging details are examined from a system performance viewpoint. The simulation study also reveals illustrative results on the impact of the EV taxi fleet's operation on the charging system. Next, a real-time shared-taxi operation scheme that allows ride sharing with other passengers is proposed to maximize the operational efficiency. The simulation results suggest that the shared-taxi concept can be a viable option to improve on the limitations caused by EV operation. In addition, the importance of projected charging demands and queue delays at different charging locations are also addressed. Some limitations and a future research agenda are also discussed.     

Limits to creative destruction and technologies in practice: the case of ham radio

Drawing on the structurationist notion of ‘technologies-in-practice’, this article analyses the different types of technological actions that users perform, after technological change, in order to keep a declining technology alive over time. The research question of the article is: How do technologies-in-practice based on the application of new technology hamper the creative destruction of old technology? The case study of ham radio technology and amateur radio operators is explored. The results of the investigation support the development of a technology-in-practice ‘experimentation’ and four inductive research propositions.     

Electrification of a city bus network—An optimization model for cost-effective placing of charging infrastructure and battery sizing of fast-charging electric bus systems

The deployment of battery-powered electric bus systems within the public transportation sector plays an important role in increasing energy efficiency and abating emissions. Rising attention is given to bus systems using fast charging technology. This concept requires a comprehensive infrastructure to equip bus routes with charging stations. The combination of charging infrastructure and bus batteries needs a reliable energy supply to maintain a stable bus operation even under demanding conditions. An efficient layout of the charging infrastructure and an appropriate dimensioning of battery capacity are crucial to minimize the total cost of ownership and to enable an energetically feasible bus operation. In this work, the central issue of jointly optimizing the charging infrastructure and battery capacity is described by a capacitated set covering problem. A mixed-integer linear optimization model is developed to determine the minimum number and location of required charging stations for a bus network as well as the adequate battery capacity for each bus line. The bus energy consumption for each route segment is determined based on individual route, bus type, traffic, and other information. Different scenarios are examined in order to assess the influence of charging power, climate, and changing operating conditions. The findings reveal significant differences in terms of required infrastructure. Moreover, the results highlight a trade-off between battery capacity and charging infrastructure under different operational and infrastructure conditions. This paper addresses upcoming challenges for transport authorities during the electrification process of the bus fleets and sharpens the focus on infrastructural issues related to the fast charging concept.     

LTE-A D2D通信中的无线资源管理技术研究

本文在介绍LTE A蜂窝系统D2D通信技术原理的基础上,重点分析研究了其中的无线资源管理技术,包括模式选择技术、资源分配技术、功率控制技术等,并给出了基于分数频分复用的资源分配实现方案和以最大化网络速率和为目标的最优功率控制方案。     

基于ZigBee技术的高校智能楼宇照明控制系统设计

在对无线智能照明系统的特点进行简单介绍的基础上,提出了一种基于Zig Bee无线网络技术的高校智能建筑灯光控制系统的实现。硬件设计基于支持Zig Bee的So C芯片CC2530,软件设计基于Z-Stack协议栈。该系统具有上电后自组网的功能,用户可以控制协调器通过路由器向路由器节点上的任意一个终端设备发送信号,终端设备收到信号后,执行对照明设备的控制。     

如何做好GSM网络的维护与优化工作

GSM网络的维护工作是一个循环闭合的过程,其设计、工程建设、维护、优化工作的循环往复才能铸就优秀的无线网络。所以只有切实注重每个环节,才能把网络建设好、维护好。文章介绍了影响GSM网络的维护的因素,维护的措施,并阐述了维护和优化GSM网络的意义。     

高等院校无线数字化校园建设

随着移动技术的发展及无线设备的普及,大量利用手机或其他移动设备接入网络的时代已经来临。高校网络应用无线化已经成为信息化建设的发展趋势。