The allocation of storage space for transshipment in vehicle distribution

We address the planning of transportation and storage capacity over time. In intermodal transshipment terminals, finished vehicles are assigned to yard locations for intermediate storage. The evolutionary algorithm proposed evolves a period-oriented capacity utilization strategy. This capacity utilization strategy then controls a construction heuristic which assigns vehicle movements to periods and vehicles to storage locations. It is aimed at efficient operations and at a balanced distribution of vehicle movements over the periods of the planning horizon.     

Planning helicopter logistics in disaster relief

This paper describes an efficient planning system for coordinating helicopter operations in disaster relief. This system can be used as a simulation tool in contingency panning for better disaster preparedness and helps to generate plans with estimated data. The proposed system consists of a mathematical model and a Route Management Procedure (RMP) that post-processes the outputs of the model. The system is concerned with helicopter operations that involve last mile distribution and pickups for post-disaster medical care and injured evacuation. Delivering items such as medicine, vaccines, blood, i.v., etc. to affected locations, and evacuating injured persons from these locations comprise the transportation tasks to be performed by helicopters. The proposed modeling system accommodates the special aviation constraints of helicopters and it can handle large scale helicopter missions. The goal of the system is to minimize the total mission time required to complete the transportation task. The RMP enables the Decision Maker (DM) to specify either the mission completion time or the number of vehicles available for the mission. Respecting the limitations imposed by the DM, the RMP generates fuel and capacity feasible helicopter itineraries that complete within the specified mission completion time. A scenario that is based on the post-earthquake damage data provided by the Disaster Coordination Center of Istanbul is used for testing the method.     

Measurement and Analysis of Vibration Levels in Two and Three Wheel Delivery Vehicles in Southeast Asia

Different types of small vehicles such as two‐wheel and three‐wheel motorcycles are commonly used for domestic delivery in many countries in Asia, particularly in Southeast (SE) Asia. These types of vehicles are mostly used for delivery of packages in the last leg of the supply chain. This study was initiated at the Technical Council meeting of International Safe Transit Association to understand the vibration levels that exist in delivering packages in SE Asia for the ‘last leg’. The study measured the vibration levels that are experienced by packages in Thailand and Indonesia. The delivery process in these countries uses two‐wheel and three‐wheel light vehicles to deliver printers and small packages. However, this portion of data and testing has often been overlooked by packaging test standards used in North America and Europe to design and test packages during the development process. The ‘last leg’ delivery method discussed has generally been considered the fast, convenient and flexible way of product delivery. Data recorders were mounted on the vehicle floor to measure acceleration levels during delivery in commonly used routes in the major cities in these two countries. Measured data in this research show that the vibration levels in these ‘last leg’ delivery routes are actually lower than those measured in truck and container shipment across road and rail transportation in North America that has been previously studied by the authors. Vibration levels in the two‐wheel vehicles with rear trunk containers were higher than those in the three‐wheel vehicles. Copyright © 2015 John Wiley & Sons, Ltd.     

Multi-attribute label matching algorithms for vehicle routing problems with time windows and backhauls

We consider the class of vehicle routing problems with backhauls and time window constraints. Our motivating application is the land transportation of air-cargo freight forwarders, which requires fast solution times and the ability to handle various operational issues such as heterogeneous vehicles, multiple trips per vehicle, and penalty for early arrival at customer sites. We formulate the problem in the framework of label matching where the labels have multiple attributes representing the states of vehicles at customer locations or possible routes that vehicles may continue to cover. Two optimization-based heuristics are developed. Experimental tests on random problems and real data show that the methods can produce quality solutions quickly and are flexible in incorporating complex constraints.     

模糊需求条件下应急物资调度的动态决策研究

针对大规模突发事件的应急物资调度问题,考虑了包含供应点、集配中心和需求点的三级供应网络、模糊需求条件、多种运输方式联合运输,建立了以总运输时间和应急成本为目标的多目标非线性整数规划模型。通过决策者对总运输时间和应急成本的动态赋权,提高了模型的柔性。给出了求解算法,仿真实例验证了模型的有效性。     

Infield logistics planning for crop-harvesting operations

Crop-harvesting operations are typically carried out with combine harvesters. The harvested product is transferred to one or more tractors every time the combine harvester's storage capacity is reached. The efficiency of the process can be significantly improved by computing optimal routes and interactions for the harvest vehicles in the field. Furthermore, an automated method for generating itineraries for the harvest vehicles facilitates the planning for autonomous agricultural vehicles. The infield logistics problem is formulated as an integer linear programming vehicle routing problem with additional turn penalty constraints, but, because of the high number of decision variables, it is not possible to solve cases of realistic field size. The solution time of the infield logistics problem is considerably reduced by reformulating it as a modified minimum-cost network flow problem. This specific structure allows the exact solution of intermediate-size planning problems in a much shorter time period. The result of solving the infield logistics problem with the proposed modelling approaches is a set of itineraries (‘tours’), covering the entire field. Each ‘tour’ is characterized by the combine harvester's start and end points and the positions where the combine harvester needs to be unloaded. The planning models minimize non-productivity (i.e. the time when a combine harvester travels in a field without harvesting). The results indicate that coordination between combine harvesters and tractors is also improved.     

Two-stage stochastic programming with robust constraints for the logistics network post-disruption response strategy optimization

Logistics networks (LNs) are essential for the transportation and distribution of goods or services from suppliers to consumers. However, LNs with complex structures are more vulnerable to disruptions due to natural disasters and accidents. To address the LN post-disruption response strategy optimization problem, this study proposes a novel two-stage stochastic programming model with robust delivery time constraints. The proposed model jointly optimizes the new-line-opening and rerouting decisions in the face of uncertain transport demands and transportation times. To enhance the robustness of the response strategy obtained, the conditional value at risk (CVaR) criterion is utilized to reduce the operational risk, and robust constraints based on the scenario-based uncertainty sets are proposed to guarantee the delivery time requirement. An equivalent tractable mixed-integer linear programming reformulation is further derived by linearizing the CVaR objective function and dualizing the infinite number of robust constraints into finite ones. A case study based on the practical operations of the JD LN is conducted to validate the practical significance of the proposed model. A comparison with the rerouting strategy and two benchmark models demonstrates the superiority of the proposed model in terms of operational cost, delivery time, and loading rate.     

A coordinated two-phase approach for operational decisions with vehicle routing in a single-vendor multi-buyer system

This study considers a two-echelon system in which a vendor produces a product at a finite production rate and supplies it to several buyers facing independent normally-distributed demands. The product is delivered to the buyers using a set of different speed vehicles with identical capacity and different operating costs. The issues of lead time reduction and the service level constraint on the buyers have been incorporated in the model. A model is formulated to determine the optimal production–inventory policy, vehicle routes and vehicle type for each route by minimising the related production, inventory, lead time crashing and transportation costs of the system while satisfying the service level constraint on each buyer. A coordinated two-phase iterative approach is proposed to solve the model. Finally, a numerical example is included to describe the solution approach and illustrate the results.     

Shape optimization of flow guides in three‐dimensional extrusion processes by an approximation scheme based on state variable linearization

A new scheme of shape optimization is applied to the design of a flow guide in flat‐die extrusion processes. In general, tremendous time is inevitably required for the optimization of large‐scale three‐dimensional extrusion processes. This is because the finite element analysis requires large computation time owing to the complexity of the die geometry and flow behaviour. The proposed scheme effectively reduces the computation time for the optimization process by approximating the objective function. This is achieved by introducing a transformed equation of the state variables. The scheme is then applied to the practical extrusion processes to produce ‘l’, ‘H’ and ‘L’ sections. The objective of the optimization is to make a balanced flow of the material in the exit region. Control points of a Bezier curve describing the outline of the flow guide are regarded as the design variables. Through application to large‐scale problems, the effectiveness and usefulness of the proposed scheme is demonstrated. Copyright © 2005 John Wiley & Sons, Ltd.     

Reducing CO2 emissions from the rebalancing operation of the bike-sharing system in Beijing

With the development of the bike-sharing system (BSS) and the introduction of green and low carbon development, the environmental impacts of BSS had received increasing attention in recent years. However, the emissions from the rebalancing of BSS, where fossil-fueled vehicles are commonly used, are usually neglected, which goes against the idea of green travel in a sharing economy. Previous studies on the bike-sharing rebalancing problem (BRP), which is considered NP-hard, have mainly focused on algorithm innovation instead of improving the solution model, thereby hindering the application of many existing models in large-scale BRP. This study then proposes a method for optimizing the CO₂ emissions from BRP and takes the BSS of Beijing as a demonstration. We initially analyze the spatial and temporal characteristics of BSS, especially the flow between districts, and find that each district can be independently rebalanced. Afterward, we develop a rebalancing optimization model based on a partitioning strategy to avoid deciding the number of bikes being loaded or unloaded at each parking node. We then employ the tabu search algorithm to solve the model. Results show that (i) due to over launch and lack of planning in rebalancing, the BSS in Beijing shows great potential for optimization, such as by reducing the number of vehicle routes, CO₂ emissions, and unmet demands; (ii) the CO₂ emissions of BSS in Beijing can be reduced by 57.5% by forming balanced parking nodes at the end of the day and decreasing the repetition of vehicle routes and the loads of vehicles; and (iii) the launch amounts of bikes in specific districts, such as Shijingshan and Mentougou, should be increased.     

Gantry crane scheduling in intermodal rail-road container terminals

Modern rail-road container terminals serve as important consolidation nodes in intermodal transportation networks where containers are transferred between freight trains and trucks. Among the most important decision problems in these yards is the crane scheduling problem, which decides on the sequences of container moves executed by each of the parallel gantry cranes. This paper treats a rich crane scheduling problem, which considers plenty relevant constraints and is directly applicable in Chinese intermodal terminals. For solving this problem, we propose a fix-and-optimise procedure, which is easy to implement and shown to successfully solve even large-sized instances with 100 container moves in reasonable time.     

带时限与回程的配送中心运输调度问题研究

在优化模型中将配送任务执行时间及每日调用车辆数量及路径作为决策对象,以车辆的固定费用、行驶费用、未按时完成服务产生的惩罚、存储费用等作为优化目标。在遗传算法中采用自然数编码形式以便于优化车辆数量,采用基于扫描算法的启发式算法构造更好的初始解,引入单亲遗传算子、重启机制及并行禁忌搜索以提高种群质量和深度寻优。经不同规模算例间对比测试,显示基于扫描算法的混合遗传算法具有最佳的优化性能。     

CFD-based optimization of hovering rotors using radial basis functions for shape parameterization and mesh deformation

Aerodynamic shape optimization of a helicopter rotor in hover is presented, using compressible CFD as the aerodynamic model. An efficient domain element shape parameterization method is used as the surface control and deformation method, and is linked to a radial basis function global interpolation, to provide direct transfer of domain element movements into deformations of the design surface and the CFD volume mesh, and so both the geometry control and volume mesh deformation problems are solved simultaneously. This method is independent of mesh type (structured or unstructured) or size, and optimization independence from the flow solver is achieved by obtaining sensitivity information for an advanced parallel gradient-based algorithm by finite-difference, resulting in a flexible method of ‘wrap-around’ optimization. This paper presents results of the method applied to hovering rotors using local and global design parameters, allowing a large geometric design space. Results are presented for two transonic tip Mach numbers, with minimum torque as the objective, and strict constraints applied on thrust, internal volume and root moments. This is believed to be the first free form design optimization of a rotor blade using compressible CFD as the aerodynamic model, and large geometric deformations are demonstrated, resulting in significant torque reductions, with off-design performance also improved.     

Analysis of Categorical Response in Small Sample Experiments

Statistical design of experiments (DOE) is widely used today for process and product characterization and optimization. Owing to cost and time considerations, sometimes only a minimum number of experimental runs can be conducted, with added challenges in analysis when the experimental outcomes cannot be measured on a continuous scale and are expressed only in qualitative terms such as ‘excellent’, ‘satisfactory’ and ‘poor’: such outcomes are variously described as ‘categorical’, ‘attribute’, ‘qualitative’, ‘discrete’ or ‘counted’ in nature. This paper offers practical techniques of handling small experiments with such non‐standard DOE response data which are otherwise impossible to analyze by standard statistical software. The suggested procedures, built upon what is called a Likelihood Transfer Function (LTF), do not require complex data analysis but would yield results consistent with the constraints of experimental conditions as well as the objectives of stakeholders. Copyright © 2015 John Wiley & Sons, Ltd.     

Models for the schedule optimization problem at a public transit terminal

This work deals with the proposal of some models for the schedule optimization problem for public transit networks. In particular, we consider the case of a transit terminal where passengers are supposed to split among different lines of a service, or even change mode of transportation in case of intermodal systems. Starting from a given schedule for the transit lines arriving at the terminal, the aim is to decide the optimal schedule for the output lines, in such a way to balance the operative costs of the service and the passenger waiting time at the transit terminal. We propose two different models for this problem, which present strong similarities with some well known combinatorial optimization models. Computational results are also presented, showing the suitability of the models to solve real case studies.     

Cash transportation vehicle routing and scheduling under stochastic travel times

Stochastic disturbances occurring in real-world operations could have a significant influence on the planned routing and scheduling results of cash transportation vehicles. In this study, a time–space network flow technique is utilized to construct a cash transportation vehicle routing and scheduling model incorporating stochastic travel times. In addition, to help security carriers to formulate more flexible routes and schedules, a concept of the similarity of time and space for vehicle routing and scheduling is incorporated into the model. The test results show that the model could be useful for security carriers in actual practice.     

具有模糊时间窗的多模式联运建模及优化

以考虑用户偏好的模糊时间窗多式联运为研究对象,建立了基于图状结构的模糊时间多式联运模型。在分析模型特征的基础上,设计了基于正交试验的混合田口遗传算法实现路径及运输方式的组合优化。通过考虑不同用户偏好的5个任务来考察模型和优化算法的有效性。计算结果表明,该算法能有效求解出满足用户偏好的路径及运输组合方式,为物流企业决策提供依据。     

基于分组策略的多目标三维装箱算法

目的 针对现有三维装箱算法优化目标单一、优化效率低的问题,提出适用于求解大规模货物装载问题的多目标装箱算法,以提高装箱规划效率,确保货物运输安全。方法 考虑5种现实约束条件,以体积利用率和装载垛型重心偏移量为优化目标,建立多目标货物装载优化模型。采用拟人式装箱对货物进行预分组,减小决策空间,然后结合分组信息与装箱算法生成初始解;引入数据驱动的装箱交叉算子提高算法收敛性;设计多策略变异算子提高算法结果的多样性。结果 以公共数据集和真实航空货物数据作为实验数据进行实验。实验结果表明,在满足多种约束条件下,集装箱装载强异构货物平均体积利用率达到92.0%,重心位置空间偏移从20 cm减少到7.5 cm,并且算法运行时间减少了73.5%。结论 本文所提算法应用于求解大规模多目标三维装箱问题,提高了装箱质量和效率,可为三维装箱算法的工程应用提供参考。     

Measurement and Analysis of Physical and Climatic Distribution Environment for Air Package Shipment

There has been a significant growth in the air package shipment business, which involves the multi‐modal movement of a package in transportation and material handling systems that encompass conveyors, carts, trucks, delivery vans and aircrafts of various sizes and shapes. This study was aimed at establishing the ‘air package shipment’ conditions experienced by packages transported by air under ‘normal conditions of transport’. Air package shipment data (temperature, humidity, pressure, shock and vibration) were collected for several domestic and international routes through instrumented packages. The collected data were supplemented by previous research to measure and quantify this multi‐modal shipping environment. This study also compared industry‐accepted American Society for Testing and Materials (ASTM) pre‐shipment test methods with the general requirements of package design qualification testing as outlined in 49 Code of Federal Regulations (CFR) Part 178, Subpart M. This review revealed that the design qualification testing for certain distribution‐related hazard elements is not currently representative of the normal conditions of air transport. The data gathered in this study were analysed to represent the current ‘normal conditions of transport’, i.e. beginning‐to‐end delivery of air packages. The study used the time spent by the package in each of the segments of transportation to determine a ‘single profile’ or ‘test’ that would represent the average and normal expected levels for each hazard element and would serve as the basis of a minimum level for performance testing to establish normal conditions of transport by air. The recommended test methods and levels can be easily adopted by existing distribution packaging testing labs globally. Copyright © 2015 John Wiley & Sons, Ltd.