Instantaneous communication throughputs of vehicular ad hoc networks

Vehicular ad hoc networks (VANETs) formed by connected vehicles in a traffic stream could be applied to improve safety, mobility, and environmental impacts of a transportation system. In this paper, we present analytical models for the instantaneous communication throughputs of VANETs to measure the efficiency of information propagation under various traffic conditions at a time instant. In particular, we define broadcast and unicast communication throughputs by the wireless channel bandwith multiplied by the average probabilities that one vehicle is a successful receiver and sender in a VAENT, respectively. With a protocol communication model, we derive formulas to determine the probabilities for an equipped vehicle to be a successful broadcast receiver and a successful unicast receiver/sender, and obtain broadcast and unicast throughputs along discrete and continuous traffic streams. We further examine the impacts on communication throughputs of the transmission range and the interference range of dedicated short range communication devices as well as the market penetration rate of equipped vehicles and the percentage of senders. Finally, we investigate the influence of shock waves on communication throughputs.     

Workshop report - Beyond competitive tendering

Most countries contemplating the introduction of competition-based organizational forms did not perceive the British deregulated bus regime to be the way forward. A deeper analysis of facts and an international coverage of the local successes of that regime remained marginal and, as a result, the reputation of deregulated regimes remained bad or - at best - a contentious issue. The rush for competitive tendering was further stimulated by the European Commission’s endeavour to enact a Regulation that put forward competitive tendering of exclusive contracts as the preferred way to organise local public transport markets. Yet, as discussed in this workshop, deregulation in various guises may well play a growing role in local and regional transport. This is already visible in long-distance coach transport and in (international) European railway markets as from 2010. The workshop paper discusses whether such competition-based institutional alternatives to competitive tendering can provide efficiency and service improvements, how such competition-based alternatives should be ‘regulated’ and, alternatively, how a non-competitive direct award could perhaps still guarantee good performance.     

航运市场中的牛鞭效应研究

揭示了航运市场中存在的牛鞭效应。结合航运产品的特点及H.L.Lee对牛鞭效应的研究,分析了对航运产品需求的预测、船舶建造周期、批量运输及运输的不平衡性、运输价格的波动、定量供应与短缺博弈是产生航运市场牛鞭效应的主要原因,并由此提出了相应的对策框架。     

铁路货运市场化定价机制探讨

为发挥价格政策对资源配置的引导和调节作用,以提高效益为目的,综合运用各种价格调节手段,构建合理的运价体系和结构,理顺不同环节间的价格关系,实现科学合理定价,在分析货运价格体系现状的基础上,提出市场化定价的基本原则和定价依据,从运作机制、定价关系、定价手段等方面对铁路货运市场化定价进行研究,制定实施符合铁路运输行业特征、...     

2012年乘用车市场分析与预测

文章分析了2012年我国乘用车市场情况,提出2012年乘用车需求主要受3方面因素影响。一是乘用车自身发展规律,即从发达国家经验来看,汽车发展有2个阶段;二是宏观经济形势,2012年经济增长率低于长期潜在水平;三是政策影响,不会出台全局性的鼓励和限制总量的政策。,并预计2012年乘用车增长率在12％左右。     

影响经济型车市场的若干因素分析

首先通过统计数据，说明2005年初以来经济型车市场的繁荣状况。并通过汽车的购买和使用成本、国家有关行业指导性政策、汽车产品定位和消费升级及宏观经济4个角度进行分析，预测了经济型车市场的巨大容量和发展潜力。同时，简要阐述了对经济型车厂商的规划思路和产业格局的理解。     

市场经济下的工程量清单计价与定额计价的思考

我国的工程造价长期以来按照传统的定额模式进行计价,目前推行工程量清单计价模式。工程量清单计价模式实行量价分离,由企业根据自身情况按市场规律自主报价,但是,工程量清单计价模式在并不成熟的市场经济条件下还不能彻底取代传统的定额计价模式,按定额编制概（预）算的造价管理方法仍然具有不可替代的作用,尽管如此,工程量清单计价的推行乃大势所趋。     

航运市场预测方法研究

引入灰色理论和回归预测模型,提出预测海运市场容量的方法,运用马尔科夫法预测未来公司的市场占有率,并运用敏感性分析搜寻盈利的关键因素。结合实例计算分析,证明该方法的衫性与有效性。     

船舶低硫燃油系统的应用分析

介绍低硫燃油的特性及其关键技术,分析低硫燃油市场供应情况,结合工程应用实际,提出了4种应用方案,经过对比分析,提出了一种面向工程实际的推荐方案。     

论中国轿车市场上买主的分类与特征

中国轿车市场上有三类买主。第一类为公务车买主是国家,第二类为私务车买主,第三类为私人生活车买主。