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861.
考虑时间因素的运输方式选择问题 总被引:1,自引:1,他引:0
本文先对各类运输方式做了概括论述,在着重考虑时间因索的前提下对运输方式的选 择进行了定量分析,提出了利用最小花费来完成运输任务的运输方式选择模型,并分析了该摸 型的求解过程,有助干运输消费者选择经济、合理的运输方式。 相似文献
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从城市GDP、交通基础设施、货运量、货运车辆调度、能源和环境6 个要素出发,构建城市货运交通系统动力学模型,对比实施共同配送前后对城市货运交通拥堵、运输费用及货运系统节能减排的效益变化,寻求解决路径. 以济南市为例,确定模型参数及方程,动态仿真实施共同配送的效益. 结果表明:随着载货率提高、平均运距的增长,实施共同配送的边际收益呈递减趋势,配送时间的昼夜错峰调整也有显著影响;在决策区间载货率[70%, 80%]、平均运距[70, 80] km、配送时间昼夜比例[6∶4,7∶3]下,共同配送总体效益最优;节能减排效益仍存在挖掘的潜力,通过提高新能源货运车承担的货运比重,每20%的增加将带来货运系统节能减排平均30%的降低. 相似文献
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技术计划空车调整的数学模型 总被引:1,自引:1,他引:0
将经济数学和运筹学中的数学方法应用于铁路运输生产技术计划的编制当中,抽象出空车调整的数学模型,并对该模型的理论和实现作了详细的介绍.目前,该方法已经全面应用于铁道部和原14个铁路局的技术计划编制工作当中并收到良好的效果. 相似文献
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Cities are complex systems, where related Human activities are increasingly difficult to explore within. In order to understand urban processes and to gain deeper knowledge about cities, the potential of location-based social networks like Twitter could be used a promising example to explore latent relationships of underlying mobility patterns. In this paper, we therefore present an approach using a geographic self-organizing map (Geo-SOM) to uncover and compare previously unseen patterns from social media and authoritative data. The results, which we validated with Live Traffic Disruption (TIMS) feeds from Transport for London, show that the observed geospatial and temporal patterns between special events (r = 0.73), traffic incidents (r = 0.59) and hazard disruptions (r = 0.41) from TIMS, are strongly correlated with traffic-related, georeferenced tweets. Hence, we conclude that tweets can be used as a proxy indicator to detect collective mobility events and may help to provide stakeholders and decision makers with complementary information on complex mobility processes. 相似文献
869.
This paper is at the conjunction of arguments for gender equity in transport services on one hand and need to move towards low carbon transport on the other in a developing country city. The case study city, Rajkot, a mid-sized Indian city with mixed land use and limited public transport at the time of this study, has short trip lengths and low trip rates. But, even in this city there is gender disparity in travel pattern. Thus, trip rates and trip lengths of women in the city in each of the income group are lower than that of their male counter parts. With the increase in income, both, the trip rates and lengths increase, but, the increase is higher for men than for women. While the large proportions of women in each income group walk, that among the lowest income group walking is the predominant mode, as they are ‘no-choice’ or ‘forced’ walkers. With the increase in household income, women tend to shift to para-transit and men to personal motorized transport. If sustainability arguments or climate policies are to target retaining the current low ecological footprint of the women as one of the strategies, it needs to cater to expansion of their mobility while improving infrastructure to support the same. 相似文献
870.
Increasing attention is being paid to airborne particles in railway environments because of their potential to adversely affect health. In this study, we investigate the contribution of moving trains to both the concentration and size distribution of particles in tunnel environments. Real-time measurements were taken with high time-resolution instruments at a railway station platform in a tunnel in Stockholm in January 2013. The results show that individual trains stopping and starting at the platform substantially elevate the particulate concentrations with a mobility diameter greater than 100 nm. Two size modes of the particulate number concentrations were obtained. A mode of around 170 nm occurs when a train moves, while the other mode peaks at about 30 nm when there is no train in the station. By using principal component analysis (PCA), three contributing sources were identified on the basis of the classification of the sizes of the particles, namely railway-related mechanical wear, suspension due to the movement of trains and sparking of electric-powered components. It is concluded that the particulate matter released by individual moving trains is a key contributor to fine particles (100–500 nm) on the railway platform in a tunnel. 相似文献