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1.
王智鹏 《铁道标准设计通讯》2019,(4):4-9
针对铁路规划项目功能定位定性分析为主的客观性不足问题,以宝鸡至汉中铁路为研究对象,选取节点间旅客交流时间或节点间运输距离为权重,运用Space L构造法建立区域铁路客、货运输网络拓扑结构模型;采用复杂网络分析方法,基于"有无对比"思想及等级化线路技术标准,结合应用Pajek软件与R软件,测算区域铁路运输网络直径、平均距离、边介数、网络效率等加权特征参数,以及非加权特征参数集聚系数进行网络测度分析,并进行网络最小生成树分析;以网络分析结果为基础,从路网、通道、客运、货运四个方面对铁路规划项目功能进行定量化综合定位,宝汉铁路为宁陕及陇东地区与川渝地区间南北纵向新通道的骨架干线,是一条以货为主、客货共线的区域路网干线铁路。 相似文献
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采用薄层层析法测定混苯接触工人尿中马尿酸和甲苯马尿酸的排出量,同时,测定车间空气中甲苯和二甲苯浓度,结果提示尿中代谢物浓度与车间空气浓度和接触时间的乘积有高度相关性,认为可以作为生物监测指标。 相似文献
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In mode choice decision, travelers consider not only travel time but also reliability of its modes. In this paper, reliability was expressed in terms of standard deviation and maximum delay that were measured based on triangular distribution. In order to estimate value of time and value of reliability, the Multinomial and Nested Logit models were used. The analysis results revealed that reliability is an important factor affecting mode choice decisions. Elasticity is used to estimate the impacts of the different policies and system improvements for water transportation mode. Among these policies, decision maker can assess and select the best alternative by doing the benefit and cost analysis based on a new market share, the value of time, and the value of reliability. Finally, a set of promising policies and system improvement of the water transportation were proposed. 相似文献
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曹德志 《铁道标准设计通讯》2018,(1):59-63
随着近年来客货共线铁路轨道铺设技术的进步,双块式轨道、枕式无砟道岔等新的轨道结构大量应用,原《客货共线铁路轨道工程施工技术指南》及《有砟轨道铁路铺砟整道施工作业指南》,已不能完全适应当前客货共线铁路发展需要,部分新技术内容施工标准缺失,而且其中的部分条款内容不完善,无法满足新技术的推广和施工过程中质量控制,需要重新制定相应的标准。通过深入现场,对双块式无砟轨道施工、铺砟整道、无缝线路铺设、道岔铺设、轨道与相关专业接口等关键技术进行研究,深入分析施工技术要求及控制标准,研究编制《客货共线铁路轨道工程施工技术规程》,对新研究编制的规程的主要编制原则、研究的关键技术内容、实施要点等进行阐述,便于使新标准得到更好的理解和执行。 相似文献
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In this paper, we report on the construction of a new framework for simulating mixed traffic consisting of cars, trams, and pedestrians that can be used to support discussions about road management, signal control, and public transit. Specifically, a layered road structure that was designed for car traffic simulations was extended to interact with an existing one-dimensional (1D) car-following model and a two-dimensional (2D) discrete choice model for pedestrians. The car model, pedestrian model, and interaction rules implemented in the proposed framework were verified through simulations involving simple road environments. The resulting simulated values were in near agreement with the empirical data. We then used the proposed framework to assess the impact of a tramway extension plan for a real city. The simulation results showed that the impact of the proposed tramway on existing car traffic would not be serious, and by extension, implied that the proposed framework could help stakeholders decide on expansion scenarios that are satisfactory to both tram users and private car owners. 相似文献
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To curb emissions, containerized shipping lines face the traditional trade-off between cost and emissions (CO2 and SOx) reduction. This paper considers this element in the context of liner service design and proposes a mixed integer linear programming (MILP) model based on a multi-commodity pickup and delivery arc-flow formulation. The objective is to maximize the profit by selecting the ports to be visited, the sequence of port visit, the cargo flows between ports, as well as the number/operating speeds of vessels on each arc of the selected route. The problem also considers that Emission Control Areas (ECAs) exist in the liner network and accounts for the vessel carrying capacity. In addition to using the MILP solver of CPLEX, we develop in the paper a specific genetic algorithm (GA) based heuristic and show that it gives the possibility to reach an optimal solution when solving large size instances. 相似文献
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随着客户运输需求的多样化升级,采用铁路混装货物装运模式在提升铁路运输效率、吸引多样货源等方面相较于单一品名装运显示出一定的优越性,同时混装货物装运面临的安全压力相较于单一品名装运出现骤增。为保障铁路混装货物装运安全,在阐述混装货物装运特点及安全控制要点的基础上,从"人防""物防""技防"3方面构建混装货物装运安全评价指标体系,采用层次分析法确定各指标权重,并利用模糊综合评价法对铁路混装货物装运安全进行评价,通过实例验证该评价方法的实用性及有效性,为铁路混装货物装运安全评价提供依据。 相似文献
10.
Representing activity-travel scheduling decisions as path choices in a time–space network is an emerging approach in the literature. In this paper, we model choices of activity, location, timing and transport mode using such an approach and seek to estimate utility parameters of recursive logit models. Relaxing the independence from irrelevant alternatives (IIA) property of the logit model in this setting raises a number of challenges. First, overlap in the network may not fully characterize perceptual correlation between paths, due to their interpretation as activity schedules. Second, the large number of states that are needed to represent all possible locations, times and activity combinations imposes major computational challenges to estimate the model. We combine recent methodological developments to build on previous work by Blom Västberg et al. (2016) and allow to model complex and realistic correlation patterns in this type of network. We use sampled choices sets in order to estimate a mixed recursive logit model in reasonable time for large-scale, dense time-space networks. Importantly, the model retains the advantage of fast predictions without sampling choice sets. In addition to estimation results, we present an extensive empirical analysis which highlights the different substitution patterns when the IIA property is relaxed, and a cross-validation study which confirms improved out-of-sample fit. 相似文献