基于车路协同多业务优先级的车载通信退避算法

为研究车路协同下不同优先级业务的通信,打破传统IEEE802.11 标准的CSMA/CA(Carrier Sense Multiple Access/Collision Avoidance)协议所采用的二进制指数退避策略（Binary Exponential Backoff, BEB）仅适用于传统业务如语音、视频等业务,而未考虑车路协同场景典型业务及其优先级的限制,提出一种面向车路协同的车载通信退避算法。首先,研究车路协同场景下的典型通信业务;然后,利用层次分析法建立了业务优先级层次结构模型,对车路协同下的业务进行了优先级的划定;最后,基于车路协同多业务优先级不同对传统BEB算法进行改进,提出一种面向车路协同的车载通信退避算法。通过仿真,验证了所提算法具有良好的适应性,可针对不同业务优先级,提供差异化的信息资源和业务传输保障,相对于传统的通信协议系统丢包率降低,系统吞吐量增加。     

从典型企业看南通市传统产业科技创新模式

推动大中型企业技术创新,加快科学技术进步和产业升级,是江苏省南通市传统产业实现跨越式发展,赶超苏南,基本实现现代化和第三步战略目标的关键。文章结合南通市传统产业典型企业的实际,分析了南通市传统产业技术创新的四种模式。一是以模仿创新为基础的二次技术创新模式,二是以优势互补实现双赢为目标的合作技术创新模式,三是自主创新的科技创新模式,四是非核心技术的创新模式。     

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智能交通系统（ITS）是目前世界交通运输领域的前沿研究领域,也是未来交通运输系统的重要发展方向;而智能道路系统（IRS）作为ITS的重要组成部分,一直是世界交通发达国家研究、发展与应用的热点。结合我国道路交通基础设施的发展现状,面向国内智能道路系统的应用与发展需求,分析了智能道路系统的概念及其内涵,提出了智能道路系统的体系框架结构,深入讨论了实现智能道路系统集成所面临的若干关键以及难点技术,并对智能道路系统今后的发展与应用趋势作了总结。     

大学英语教学中合作学习模式的应用

合作学习是一种以小组活动为主要形式的教学理论与策略体系。合作学习理论为我们提供了大学英语学习的新视角,促进了教学的多维互动,催生了大学英语课堂教学的新形式,更新了教学的评价机制。了解合作学习的模式、合作学习在大学英语教学中的实施和其在现实教学中存在的一些问题,有利于更好地做好大学英语教学工作。     

关于不同类型农村社区治理模式的思考

新农村建设的关键在于农村社区的建设,而治理模式的选择决定了农村社区建设的效果,从社区治理理论分析着手,结合我国各地农村的不同特点,提出治理模式的三种进路选择,为理论研究与政府决策提供相关参考。     

Analysis of a cooperative variable speed limit system using microscopic traffic simulation

Variable speed limit systems where variable message signs are used to show speed limits adjusted to the prevailing road or traffic conditions are installed on motorways in many countries. The objectives of variable speed limit system installations are often to decrease the number of accidents and to increase traffic efficiency. Currently, there is an interest in exploring the potential of cooperative intelligent transport systems including communication between vehicles and/or vehicles and the infrastructure. In this paper, we study the potential benefits of introducing infrastructure to vehicle communication, autonomous vehicle control and individualized speed limits in variable speed limit systems. We do this by proposing a cooperative variable speed limit system as an extension of an existing variable speed limit system. In the proposed system, communication between the infrastructure and the vehicles is used to transmit variable speed limits to upstream vehicles before the variable message signs become visible to the drivers. The system is evaluated by the means of microscopic traffic simulation. Traffic efficiency and environmental effects are considered in the analysis. The results of the study show benefits of the infrastructure to vehicle communication, autonomous vehicle control and individualized speed limits for variable speed limit systems in the form of lower acceleration rates and thereby harmonized traffic flow and reduced exhaust emissions.     

Modeling cooperative and autonomous adaptive cruise control dynamic responses using experimental data

Vehicle longitudinal control systems such as (commercially available) autonomous Adaptive Cruise Control (ACC) and its more sophisticated variant Cooperative ACC (CACC) could potentially have significant impacts on traffic flow. Accurate models of the dynamic responses of both of these systems are needed to produce realistic predictions of their effects on highway capacity and traffic flow dynamics. This paper describes the development of models of both ACC and CACC control systems that are based on real experimental data. To this end, four production vehicles were equipped with a commercial ACC system and a newly developed CACC controller. The Intelligent Driver Model (IDM) that has been widely used for ACC car-following modeling was also implemented on the production vehicles. These controllers were tested in different traffic situations in order to measure the actual responses of the vehicles. Test results indicate that: (1) the IDM controller when implemented in our experimental test vehicles does not perceptibly follow the speed changes of the preceding vehicle; (2) strings of consecutive ACC vehicles are unstable, amplifying the speed variations of preceding vehicles; and (3) strings of consecutive CACC vehicles overcome these limitations, providing smooth and stable car following responses. Simple but accurate models of the ACC and CACC vehicle following dynamics were derived from the actual measured responses of the vehicles and applied to simulations of some simple multi-vehicle car following scenarios.     

合作式教学在思想政治理论课中的实现

合作学习对形成学生的科学素养,培养学生在集体中的交往能力、合作意识,提高学生在集体中的自尊,是富有成效的一种教学组织形式.大学生具备了一定的沟通与社交技能,更适合于合作学习.思想政治理论课的教学内容虽然大多是较为固定的结论,但是我们仍然可以通过小组交流讨论来进行深入的扩展性研究,从而增强思想政治理论课的教学效果.     

基于车路协同的车灯自适应控制数学模型研究

为了有效减少夜间弯道中的交通事故,本文提出了基于车路协同的自适应车灯控制系统。以公路的停车视距、弯道曲线长度和弯道曲线转角为基础,建立车灯水平转角与路面情况的数学模型。对该模型进行模拟后,结果表明该系统在国家车路协同技术推广中具有广泛的应用前景。     

A Cooperative Intelligent Transport Systems (C‐ITS)‐based lane‐changing advisory for weaving sections

Weaving sections, a common design of motorways, require extensive lane‐change manoeuvres. Numerous studies have found that drivers tend to make their lane changes as soon as they enter the weaving section, as the traffic volume increases. Congestion builds up as a result of this high lane‐changing concentration. Importantly, such congestion also limits the use of existing infrastructure, the weaving section downstream. This behaviour thus affects both safety and operational aspects. The potential tool for managing motorways effectively and efficiently is cooperative intelligent transport systems (C‐ITS). This research investigates a lane‐change distribution advisory application based on C‐ITS for weaving vehicles in weaving sections. The objective of this research is to alleviate the lane‐changing concentration problem by coordinating weaving vehicles to ensure that such lane‐changing activities are evenly distributed over the existing weaving length. This is achieved by sending individual messages to drivers based on their location to advise them when to start their lane change. The research applied a microscopic simulation in aimsun to evaluate the proposed strategy's effectiveness in a one‐sided ramp weave. The proposed strategy was evaluated using different weaving advisory proportions, traffic demands and penetration rates. The evaluation revealed that the proposed lane‐changing advisory has the potential to significantly improve delay. Copyright © 2016 John Wiley & Sons, Ltd.