基于GPS／GSM／GIS集成的动态车辆优化调度的研究

目前,GPS(全球定位系统)、GSM(数字蜂窝移动通信系统)和GIS(地理信息系统)都是成熟的商业技术。运用这些技术,再结合Dijstra最短路和贪心算法,可合理实现单配送中心、非满载送货条件下的车辆优化调度,提高配送效率。     

公路桥头跳车成因分析及技术措施

桥头跳车一直是道路桥梁工程界广为关注而又一直尚未解决的重大技术难题，本文针对桥头跳车问题进行了成因分析，介绍了其危害性及可行的几种防治措施，为进一步解决这一问题提供一些可实施的方法。     

从喻体和喻义看英汉比喻的文化差异

比喻性习语在英汉语言中大量存在,但由于两种语言反映的文化不同,使得英汉习语在比喻形象的运用上存在明显差异。文章介绍和比较了三种喻体在各自习语中的使用情况,并提出只有了解和掌握英汉比喻中的这种文化差异,才能在跨文化交际时准确无误地传递隐含在语言里的文化信息。     

隐喻的语义认知

过去隐喻只被看作是一种修辞手段 ,当代的隐喻学家提出隐喻不仅是语言自身的问题 ,而且广泛存在与人们的思维当中 ,可以说隐喻无处不在。本文就隐喻的多种表现形式 ,阐释隐喻的多种语义特征     

具有模糊旅行时间的VRP的一种混合遗传算法

传统确定性车辆路径问题是近几十年来运筹学领域研究的一个热点问题.但在许多实际的应用中,由于受客观世界中存在的不确定性因素以及人类观察、认识事物的模糊性的影响,车辆路径问题的某些参数可能是模糊的、不确定的.文中传统确定性车辆路径问题被扩展为具有模糊特征的模糊车辆路径问题.在对具有模糊旅行时间的车辆路径问题进行简单描述的基础上,构建了该问题的数学模型,并通过将模糊逻辑、模糊控制方法与传统车辆路径问题的遗传算法进行有效结合,提出了解决该问题的一种混合遗传算法.最后给出了该问题的一个计算实例,并通过随机模拟试验验证了该算法的有效性和优越性.     

动态车辆路径问题排队模型分析

分析了一类动态车辆路径问题,其中顾客需求以泊松流形式出现,现场服务时间服从一般分布.提出解决该问题的两种策略:顺序服务策略和中点改进策略,利用排队论、几何概率论等领域的知识分别求出了这两种策略的系统时间,并通过仿真数据实验验证了这两种策略的有效性.     

新能源汽车新时代新征程:2017回顾及未来展望

随着补贴退坡和双积分等重要政策接连出台,中国新能源汽车发展进入新时代。2017年,私人购买量大幅上升到41%,汽车动力电池行业集中度上升,三元电池装机占比显著增加到44%,车桩比有所下降。双积分政策在2017年正式出台,加上国家和地方补贴的进一步退坡,新能源汽车产业加速从政策驱动过渡为市场驱动阶段。但私人消费需求还有待进一步激发,电池等关键零部件的核心技术仍需突破,充电设施的建设与运营面临挑战。双积分和补贴退坡等重要政策实施后,中国汽车行业格局将发生深刻变化。从政策支持与行业发展来看,燃料电池汽车及电动汽车智能化融合发展将是今后重要的发展方向。     

车用天然气储气技术

天然气用作汽车的代用燃料,具有储量丰富、价格便宜;辛烷值高、燃烧充分;低硫、低氮、无灰、环境污染少等优点。但是,目前的压缩天然气储气技术存在储气压力高、储气量小、续驶里程短等缺点,严重制约着天然气汽车应用领域的扩展。对5种车用天然气储气技术进行了分析讨论后,指出了吸附储存和近临界流体储存天然气技术在天然气汽车领域将有着广阔的应用前景。     

Flexible work planning of service agents with load balancing

This work emerged from the need to better plan the daily work of 29 travelling service agents, who provide 1090 services to 412 customers in 283 sites, on daily average. A handy and flexible tool was developed and is presented herein. A major contribution of this study is an explicit consideration of the multi-dimensional nature of the problem by the inclusion of workload balancing, which may stand in conflict to cost minimisation. Further, the geographical distribution of the demand is highly irregular. Therefore, two load measures are required and balanced. This required to fitting a proper planning scheme. The planning tool has been applied successfully by the commercial service provider. Improvements in the order of 20% and more were obtained in key performance measures. Moreover, cost reductions, service improvement and load balance were obtained simultaneously: the standard deviations of the service times and working day’s duration were reduced by 18 and 58%, respectively. This enables to reduce the number of agents with no significant harm in performance. Additional practical advantages of the proposed tool are also discussed and demonstrated, for example, the ability to cope with geographical distributions and the flexibility to respond to daily variations in demand.     

An evaluation of the tandem configuration automated guided vehicle system

The performance of a tandem automated guided vehicle (AGV) system is compared with that of conventional AGV track systems. In the tandem system the track is divided into non-overlapping, single-vehicle closed loops. Using simulation it is shown that, because of trips requiring delivery across loops, the tandem system has a higher expected travel time per load and thus a greater average time in system. When the loads are delivered within the original loop only, the tandem system has a lower average time in system than in conventional systems, although the difference is modest. Track layout appears to influence the average time in system much more than docs the dispatching rule invoked. The success of the tandem system is highly dependent on approximately even AGV utilization, which may be difficult to obtain in practice.