Vehicle currency use in international trade

We explore the major driving forces for currency invoicing in international trade with a simple model and a novel dataset covering 24 countries. We contrasts a “coalescing” effect, where exporters minimize the movements of their prices relative to their competitors', with incentives to hedge macroeconomic volatility and transaction costs. The key determinants of invoice currency choice are industry features and country size, with some role for foreign-exchange bid-ask spreads. The coalescing effect also goes a long way to explaining the well-known dominance of the dollar. Trade flows to the United States are predominantly invoiced in dollar, as foreign exporters face competition with U.S. firms. The use of the dollar in trade flows that do not involve the United States reflects trade in homogeneous products where firms need to keep their price in line with their competitors'.     

An exact algorithm for the multi-trip vehicle routing and scheduling problem of pickup and delivery of customers to the airport

Door-to-Door service of Pickup and Delivery of Customers to the Airport (D2PDCA) is a new service provided by certain Airline Ticket Sales Agencies (ATSAs) in China. This new service provides an attractive alternative way by picking up customer at this/her specified position and at any time he/she preferred and delivering to the airport more conveniently than airport shuttle and thus earn high customer service quality. Compared with the single-trip mode, the multi-trip mode of D2PDCA (MTM-D2PDCA) service can reduce travel distances, the number of vehicles required and the operating cost. To obtain the exact solution of the MTM-D2PDCA problem, we propose a novel, exact algorithm based on the trip-chain-oriented set-partitioning (TCO-SP) model, where a trip-chain represents multiple trips made by a specific vehicle. In the exact algorithm, we propose an improved label-correcting method to remove infeasible trip-chains quickly and thus speed the search process. Based on the feasible trip-chains, the MTM-D2PDCA problem is formulated as the novel TCO-SP model, which can be solved exactly by the optimization software CPLEX. In addition, we present several mathematical insights into the relationship between the number of trip-chains and the number of local optimal trips that are applicable in both theory and practice. Extensive experiments are conducted to illustrate the application of the model and demonstrate the cost savings of the MTM-D2PDCA mode over the single-trip mode and provide managerial insights into successfully operating a MTM-D2PDCA service.     

An integer programming approach to the bloodmobile routing problem

Every day, a blood center must determine a set of locations among a group of potential sites to route their vehicles for blood collection so as to avoid shortfalls. In this study, a vehicle routing problem is modeled using an integer programming approach to simultaneously identify number of bloodmobiles to operate and minimize the distance travelled. Additionally, the model is extended to incorporate uncertainty in blood potentials and variable durations in bloodmobile visits. Optimal routings are determined using CPLEX solver and branch-and-price algorithm. Results show that proposed algorithm solve the problem to optimality up to 30 locations within 3600 s.     

A multi-start heuristic approach for the split-delivery vehicle routing problem with minimum delivery amounts

We propose a new multi-start solution approach for the split-delivery vehicle routing problem with minimum delivery amounts (SDVRP-MDA). Initial solutions are generated by both node-insertion and route-addition procedures with a single parameter to control the restart. These solutions are then improved by a variable neighborhood descent metaheuristic with a novel search operator inspired by node-ejection chains. We test the proposed approach with 32 benchmark instances for four different minimum delivery fractions. Using the proposed algorithm, out of 128 cases tested, we find 81 best known solutions and 34 new best solutions; overall, we find 43 new best solutions.     

Model and algorithm for an unpaired pickup and delivery vehicle routing problem with split loads

This paper addresses the routing problem with unpaired pickup and delivery with split loads. An interesting factor of our problem is that the quantity and place for pickup and delivery are decision variables in the network. We develop an easy-to-implement heuristic in order to gain an efficient and feasible solution quickly. Then, a local search algorithm based on the variable neighborhood search (VNS) method is developed to improve the performance of the heuristic. Computational results show that the proposed VNS method is able to obtain an optimal or near optimal solution in reasonable time for the formulated problem.     

A dynamic hazard-based system of equations of vehicle ownership with endogenous long-term decision factors incorporating group decision making

The transportation system affects all aspects of our daily lives including relatively long-term decisions on work and home location choice and automobile ownership decisions. The interdependency existing among these three decisions jointly influences household mobility and overall travel patterns. Therefore, a dynamic modeling framework that can account for the effects of interdependencies between vehicle transaction behavior and residential and job location choices is highly desirable. These decisions are made in the household level while individuals’ decisions influence the overall outcome; therefore, it is also important to incorporate a group decision making process within such modeling frameworks.This study introduces a dynamic model for vehicle ownership, residential mobility, and employment relocation timing decisions. These decisions are modeled at the individual level and then sequentially aggregated to the household level if it is required. A hazard-based system of equations is formulated and applied in which work location and residential location changes are included as endogenous variables in the vehicle transaction model while other important factors such as land-use and built environment variables, household dynamics, and individuals’ socio-demographics are also considered.     

基于现有技术条件下我国电动汽车商业化之路

目前我国电动汽车的发展进入了瓶颈阶段,即无法实现商业化。制约电动汽车商业化的障碍主要有:电池充电时间长,效率低;整车价格贵、汽车整体运行成本高;缺乏足够的充换电网络和专业的维修网点。在现有技术条件下解决电动汽车商业化的有效途径是采取换电模式,其优点为:没有技术障碍问题、换电站投资成本低、缩短车辆的等待时间、提高电池的使用寿命、降低电池的使用成本。目前应由国家制定统一的电池标准和充电设备等标准,并依托中石油、中石化、南方电网等央企来构建充换电网络。     

Multi-agent-based transport planning in the newspaper industry

In many cases of today's planning tasks, the synchronization of production and distribution is becoming increasingly important in order to minimize costs and to maximize customer satisfaction. This is especially the case if transport schedules are closely connected to production schedules, as it is in the newspaper industry—where perishable goods are distributed immediately after production. In order to achieve the above mentioned competing objectives, a special kind of vehicle routing problem, the vehicle routing problem with time windows and cluster-dependent tour starts (VRPTWCD), has to be solved. Moreover, the varying print and post-processing schedules due to unknown editorial deadlines lead to the need for a dynamic online control of the newspaper production and distribution process. In this contribution, the outlined dynamic transport problem is solved online under consideration of unforeseen changes in production schedules. The solution concept is based on a multi-agent system consisting of, amongst others, several Edition and Vehicle Agents. This system is exemplarily applied to a real life application case of one of the largest German newspaper companies. It is shown that a static (centralized) optimization of the underlying problem would even lead to worse results in comparison to the current situation and that the appliance of the multi-agent system is suitable in the newspaper industry.     

AUV回收定位系统的设计与研究

本文针对AUV回收过程中的定位问题,提出了一种基于单片机、GPS模块以及数传电台的AUV回收定位模块设计方案,采用数传电台与GPS相结合的远程遥控方式,实现AUV回收定位系统实时采集、处理、无线传输及远程监控等功能。     

国企客运车辆公车公营模式分析

本文通过对国企客运车辆的现状分析,提出从挂靠转变为"公车公营"的车辆经营模式,并给出相应措施,对国有客运企业整体发展意义重大。