《鹿特丹规则》货物交付制度若干新变化之比较研究

货物交付制度是运输合同法律的重要内容。《鹿特丹规则》系统规定了货物交付制度,确立了收货人接收交付和确认收到货物的义务,规定了不同运输单证下的交付规则,与现行的法律比较存在诸多差异。中国航运企业应研究、借鉴货物交付新规则,完善货物交付制度。     

美军低成本空投系统(LCADS)分析及对我军的启示

简单介绍了美军空投系统的发展及建设情况,回顾了美军传统空投系统(CDS)的使用情况及存在问题,着重分析了新型低成本空投系统(LCADS)的适用性强、适用范围广泛等特性。在此基础上,从使用成本、使用效果等方面对LCADS与CDS进行了比较分析。最后根据美军空投系统的发展现状及趋势,提出了加强我军空投系统建设的几点启示,有利于促进我军后勤保障方式的发展变革。     

混凝土输送泵长距离泵送技术的应用

通过对隧道二次衬砌机械配套施工模式的技术经济分析,阐述了短隧道二次衬砌采用混凝土长距离泵送技术的可行性。为充分发挥混凝土输送泵的效率提供了参考,也为隧道施工项目的安全质量和成本控制提出了较好的建议。     

治理车辆双超智能管理信息平台的研究及实现

为了巩固全国治理车辆超限超载工作已取得的成绩,理顺治理工作业务流程,规范执法,研究了治理车辆超限超载智能管理信息平台的总体设计及其相应系统功能实现,给出了全国治理双超智能信息平台的总体构架,重点介绍了该平台的功能模块设计,探讨了构建该平台的相关关键技术。同时,以北京市省级治理车辆双超智能信息平台为例,简要介绍了治理双超智能信息平台构架的具体实现。该平台经过前期试运行表明,平台构架科学合理,能够满足治理双超工作及相关行业的业务需要,北京市省级治理车辆双超智能信息平台工作稳定可靠,提高了北京市车辆超限运输的治理水平,基本实现了平台建设的总体目标,同时为交通行业运政管理系统功能完善提供了有力支持。     

二七长江大桥2号试桩承载力自平衡测试研究

采用自平衡试桩法对二七长江大桥2号试桩进行测试,试验采集了桩身应力、荷载箱位移等数据,并采用改进荷载传递函数转换法等效转换成传统静载下的桩顶荷载及相应沉降,确定试桩单桩极限承载力.     

A decomposition-based iterative optimization algorithm for traveling salesman problem with drone

This study investigates a new delivery problem that has emerged after the attempts of several e-commerce and logistics firms to deploy drones in their operations to increase efficiency and reduce delivery times. In this problem, a delivery truck that carries a drone on its roof serves customers in coordination with a drone. The drone is considered to complement the truck due to its cost-efficiency and ability to access difficult terrains and to travel without exposure to congestion. This study presents an iterative algorithm that is based on a decomposition approach to minimize delivery completion time. In the first stage of the proposed methodology, the truck route and the customers assigned to the drone are determined. In the second stage, a mixed-integer linear programming model is solved to optimize the drone route by fixing the routing and the assignment decisions that are made in the first stage. Beginning with the shortest truck route, the assignment and the routing decisions are iteratively improved. The solution times of our algorithm are compared with the solution times of the state-of-the-art formulations that are solved by CPLEX. The results demonstrate that our algorithm yields shorter solution times for the instances that we generated with the specified parameters. An optimization-based heuristic algorithm, which obtains solutions for medium-sized instances, is developed by reducing the feasible search area.     

Understanding the impact of e-commerce on last-mile light goods vehicle activity in urban areas: The case of London

Growth in e-commerce has led to increasing use of light goods vehicles for parcel deliveries in urban areas. This paper provides an insight into the reasons behind this growth and the resulting effort required to meet the exacting delivery services offered by e-retailers which often lead to poor vehicle utilisation in the last-mile operation, as well as the duplication of delivery services in urban centres as competitors vie for business. A case study investigating current parcel delivery operations in central London identified the scale of the challenge facing the last-mile parcel delivery driver, highlighting the importance of walking which can account for 62% of the total vehicle round time and 40% of the total round distance in the operations studied. The characteristics of these operations are in direct conflict with the urban infrastructure which is being increasingly redesigned in favour of walking, cycling and public transport, reducing the kerbside accessibility for last-mile operations. The paper highlights other pressures on last-mile operators associated with managing seasonal peaks in demand; reduced lead times between customers placing orders and deliveries being made; meeting delivery time windows; first-time delivery failure rates and the need to manage high levels of product returns. It concludes by describing a range of initiatives that retailers and parcel carriers, sometimes in conjunction with city authorities, can implement to reduce the costs associated with last-mile delivery, without negatively impacting on customer service levels.     

Combining pickups and deliveries in vehicle routing – An assessment of carbon emission effects

This paper studies the effect on carbon emissions of consolidation of shipments on trucks. New positioning and communication technologies, as well as decision support systems for vehicle routing, enable better utilization of vehicle capacity, reduced travel distance, and thereby carbon emission reductions. We present a novel carbon emission analysis method that determines the emission savings obtained by an individual transport provider, who receives customer orders for outbound deliveries as well as pickup orders from supply locations. The transport provider can improve vehicle utilization by performing pickups and deliveries jointly instead of using separate trucks. In our model we assume that the transport provider minimizes costs by use of a tool that calculates detailed vehicle routing plans, i.e., an assignment of each transport order to a specific vehicle in the fleet, and the sequence of customer visit for each vehicle. We compare a basic set-up, in which pickups and deliveries are segregated and performed with separate vehicles, with two consolidation set-ups where pickups and deliveries may be mixed more or less freely on a single vehicle. By allowing mixing, the average vehicle load will increase and the total driven distance will decrease. To compare carbon emissions for the three set-ups, we use a carbon assessment method that uses the distance driven and the average load factor. An increase in the load factor can reduce part of the emission savings from consolidation. We find that emission savings are relatively large in case of small vehicles and for delivery and pickup locations that are relatively far from the depot. However, if a truck visits many demand and supply locations before returning to the depot, we observe negligible carbon emission decreases or even emission increases for consolidation set-ups, meaning that in such cases investing in consolidation through joint pickups and deliveries may not be effective. The results of our study will be useful for transport users and providers, policymakers, as well as vehicle routing technology vendors.     

Designing optimal autonomous vehicle sharing and reservation systems: A linear programming approach

Autonomous vehicle (AV) technology holds great promise for improving the efficiency of traditional vehicle sharing systems. In this paper, we investigate a new vehicle sharing system using AVs, referred to as autonomous vehicle sharing and reservation (AVSR). In such a system, travelers can request AV trips ahead of time and the AVSR system operator will optimally arrange AV pickup and delivery schedules and AV trip chains based on these requests. A linear programming model is proposed to efficiently solve for optimal solutions for AV trip chains and required fleet size through constructed AVSR networks. Case studies show that AVSR can significantly increase vehicle use rate (VUR) and consequentially reduce vehicle ownership significantly. In the meantime, it is found that the actual vehicle miles traveled (VMT) in AVSR systems is not significantly more than that of conventional taxis, despite inevitable empty hauls for vehicle relocation in AVSR systems. The results imply huge potential benefits from AVSR systems on improving mobility and sustainability of our current transportation systems.     

大型输水钢管下穿兰新客运专线方案研究

兰州市水源地建设工程彭家坪支线输水隧洞下穿兰新客运专线马耳山沟中桥,该工程须考虑桥下净空、管道桥线型、结构布置等问题。为了使管道桥下穿既有马耳山沟中桥既满足小半径反向曲线线型要求,又满足既有桥下净空和行洪要求,通过方案比选最终选择了对既有铁路运营影响最小的槽型连续弯梁方案,解决了上述关键技术难题。技术方案顺利通过审查并实施,可为类似工程提供借鉴。