结构方程模型在区域物流中心规划中的应用

区域物流规划评价过程中涉及众多隐含变量的测量和因果模型的验证,而传统的评价方法难以有效地解决这类问题,降低了评价结果的可信度,结构方程模型的应用为解决这些问题提供了新的更好的方法.构建了区域物流规划评价指标体系,利用结构方程模型对指标体系进行检验修正,并确定各指标权重,应用该指标体系及其权重对待评物流中心进行评价决策.     

集装箱货运仿真模型在珠三角港港口投资方案评估(英文)

In the Pearl River Delta (PRD), there is severe competition between container ports, particularly those in Hong Kong, Shenzhen, and Guangzhou, for collecting international maritime container cargo. In addition, the second phase of the Nansha terminal in Guangzhou’s port and the first phase of the Da Chang Bay container terminal in Shenzhen opened last year. Under these circumstances, there is an increasing need to quantitatively measure the impact these infrastructure investments have on regional cargo flows. The analysis should include the effects of container terminal construction, berth deepening, and access road construction. The authors have been developing a model for international cargo simulation (MICS) which can simulate the movement of cargo. The volume of origin-destination (OD) container cargo in the East Asian region was used as an input, in order to evaluate the effects of international freight transportation policies. This paper focuses on the PRD area and, by incorporating a more detailed network, evaluates the impact of several infrastructure investment projects on freight movement.     

环珠江三角洲地区发展港口物流的对策研究

港口作为运输网络的重要枢纽节点,在综合物流体系中占有重要地位。阐述了环珠江三角洲地区三个港口群的发展状况,分析了环珠江三角洲地区发展港口物流的优势和制约因素。从加快构建环珠江三角洲地区临港工业走廊、建设自有特色的港口物流和完善集疏运体系、促进港口物流对接三大方面提出加快环珠江三角洲地区港口物流发展的策略。     

基于强度折减法和现场监控量测的大断面隧道开挖工法适用性研究

为明确微台阶Ⅰ法在Ⅳ级围岩地层中进行快速掘进施工的适用性,依托郑万高铁保康隧道工程,采用基于强度折减法原理的数值分析方法,以位移突变和计算不收敛等为主要判据指标,对微台阶Ⅰ法施工过程中的围岩稳定性进行分析,并通过现场监控量测方法来分析隧道采用微台阶Ⅰ法施工时结构的安全性。结果表明： 1）隧道拱顶和拱肩位置的竖向位移对折减系数较为敏感,而拱脚和边墙部位的水平收敛对折减系数较为敏感; 2）采用传统的三台阶法和大机配套施工的微台阶Ⅰ法所得到的折减安全系数较为接近,微台阶Ⅰ法对施工围岩稳定性影响较小,可以保证隧道安全快速掘进,在Ⅳ级围岩地层中具有良好的适用性。     

宜万铁路齐岳山隧道F_(11)高压富水断层注浆法与冷冻法方案比选与实施

随着铁路跨越式发展需要,大量高等级的铁路即将投入建设,由于受到设计时速和地形的限制,大量的铁路地下工程需要穿越原来被认定为"施工禁区"的地段,建设者将面临更多的施工难题.宜万铁路齐岳山隧道F11断层横穿隧道长度253 m,规模极其宏大,断层带由构造角砾岩、碎裂岩和断层泥组成,胶结松散、岩体破碎,稳定性极差.现场超前深孔钻探实测单孔最大涌水量为1 800 m3/h,最大水压力2.6 MPa,高压富水的存在使断层施工难度更大.针对F11高压富水断层,将注浆法与冷冻法在安全可靠性、工法适应性、计划工期和经济性四个方面进行了比选,最终决定采取注浆法.通过现场试验与实施,顺利地完成了F11高压富水断层的注浆堵水加固,保证了隧道的安全施工.     

小型私营公路运输企业经营模式的探讨

以一个成功的单体运输企业为例,从组织机构、营销管理、生产管理、财务管理以及存在问题及困境等方面入手,探讨私营运输企业经营管理模式。     

Application of Chinese Characters in the Design and Construction of the Badaling Great Wall Station of the Beijing-Zhangjiakou High-Speed Railway北大核心CSCD

The new Badaling tunnel is the longest tunnel on the under-construction Beijing-Zhangjiakou highspeedrailway, with the Badaling Great Wall station to be built in the tunnel. This station, which is under the Badaling Great Wall historic site, is the world’s largest underground high-speed railway station with the most complicated structure and the largest overburden and excavation area. It is therefore a representative project for China’s highspeed railway development strategy, supporting infrastructure facilities for the Beijing Horticultural Expo 2019 and the 2022 Winter Olympics in Beijing, and it is important that it be of high quality and completed safely. In the de-sign and construction of the station, the glyphs of the Chinese characters of "中",”国”,”人”and”品”are used, re-spectively, along the station route, in the rescue and evacuation mode, auxiliary adit and partial excavation, which is a way to successfully integrate the art of Chinese characters into tunnel engineering. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

Evaluation of CO2 emissions from railway resurfacing maintenance activities

This paper is the world first to investigate the CO₂ impact of railway resurfacing in ballasted track bed maintenance. Railway resurfacing is an important routine maintenance activity that restores track geometry to ensure safety, reliability and utility of the asset. This study consisted of an extensive field data collection from resurfacing machineries (diesel-engine tamping machines, ballast regulators and ballast stabilisers) including travel distances, working distances, fuel consumption and construction methodologies. Fuel consumption was converted to a kg CO₂/m using the embodied energies of diesel. Analyses showed that tamping machines emitted the highest CO₂ emissions of the resurfacing machineries, followed by ballast regulators and ballast stabilisers respectively. Tamping machines processed 4.25 m of track per litre of diesel, ballast regulators processed 6.51 m of track per litre of diesel and ballast stabilisers processed 10.61 m of track per litre of diesel. The results were then compared to previous studies and a rigorous parametric study was carried out to consider long-term resurfacing CO₂ emissions on Australian railway track. The outcome of this study is unprecedented and it enables track engineers and construction managers to critically plan strategic rail maintenance and to develop environmental-friendly policies for track geometry and alignment restoration.     

Locating dry ports on a network: a case study on Tianjin Port

A mathematical model for optimizing the location of dry ports is developed. The objective is to minimize the sum of the transportation costs and the fixed facility opening/closing costs. Unlike previous research on this subject, the possibility of closing existing dry ports is investigated. The dry port location problem is formulated as an integer programming and it is shown that the CFLP is a special case of our problem. The proposed model is then applied to the port of Tianjin in China and the sensitivity analysis is performed to demonstrate the robustness of the model. Our model suggests that while Tianjin Port should open some new dry ports, it might be better off closing those existing dry ports without enough throughputs. Although all parameters estimated should be uncertain in reality, sensitivity analysis shows that the results returned by the model are quite stable.     

Vehicle routing problem and driver behaviour: a review and framework for analysis

Vehicle routing problems (VRPs) whose typical objective is to minimise total travel costs over a tour have evolved over the years with objectives ranging from minimising travel times and distances to minimising pollution and fuel consumption. However, driver behaviour continues to be neglected while planning for vehicle routes. Factors such as traffic congestion levels, monotonous drives and fatigue have an impact on the behaviour of drivers, which in turn might affect their speed-choice and route-choice behaviours. The behaviour of drivers and their subsequent decision-making owing to these factors impact the revenue of transport companies and could lead to huge losses in extreme cases. There have been studies on the behaviour of drivers in isolation, without inclusion of the objectives and constraints of the traditional routing problem. This paper presents a review of existing models of VRP, planner behaviour models in the VRP context and driver behaviour models and provides a motivation to integrate these models in a stochastic traffic environment to produce practical, economic and driver-friendly logistics solutions. The paper provides valuable insights on the relevance of behavioural issues in logistics and highlights the modelling implications of incorporating planner and driver behaviour in the framework of routing problems.