Exact and approximate solutions of the container ship stowage problem

This paper deals with a stowage plan for containers in a container ship. Containers on board a container ship are placed in stacks, located in many bays. Since the access to the containers is only from the top of the stack, a common situation is that contianers designated for port J must be unloaded and reloaded at port I (before J) in order to access containers below them, designated for port I. This operation is called “shifting”. A container ship calling many ports, may encounter a large number of shifting operations, some of which can be avoided by efficient stowage planning. In general, the stowage plan must also take into account stability and strength requirements, as well as several other constraints on the placement of containers. In this paper we deal with stowage planning in order to minimize the number of shiftings, without considering stability constraints. First, a 0–1 binary linear programming formulating is presented that can find the optimal solution for stowage in a single rectangular bay of a vessel calling a given number of ports, assuming that the number of constainers to ship is known in advance. This model was successfully implemented using the GAMS software system. It was found, however, that finding the optimal solution using this model is quite limited, because of the large number of binary variables needed for the formulation. For this reason, several alternative heuristic algorithms were developed. The one presented here is based on a “reduced” transportation matrix. Containers with the same source and destination ports are stowed in full stacks as much as possible, and only the remaining containers are allocated by the binary linear programming model. This approach often allows the stowage planning of a much larger number of containers than using the exact formulation.     

Liner shipping network design with deadlines

It is crucial for a liner shipping company to design its container shipping network. Given a set of port-to-port container shipment demands with delivery deadlines, the liner shipping company aims to design itineraries of portcalls, deploy ships on these itineraries and determine how to transport containers with the deployed ships in order to maximize its total profit. In this paper we first demonstrate NP-hardness of this problem and subsequently formulate it as a mixed-integer non-linear non-convex programming model. A column generation based heuristic method is proposed for solving this problem. Numerical experiments for container shipping on the Asia–Europe trade lane show that the proposed solution algorithm is efficient to find good quality solutions.     

集装箱轻重货物混合平衡装载模型与算法

负载平衡是集装箱装运过程中的基本约束,轻重货物混合装载时较难满足,如何精确量化负载平衡、实现轻重货物混合平衡装载亟待研究。以集装箱轻重货物混合平衡装载问题为研究对象,构造负载平衡函数,综合考虑负载平衡、位置、重量和旋转等约束,建立轻重货物混合平衡装载模型;根据对负载平衡的影响程度,将待装货物分类组成轻重货物单元,在采用评估函数和中心骨架等启发式方法分类处理的基础上,设计轻重货物混合平衡装载算法。3 000个算例表明：所提出的模型和算法能够在保证集装箱容积利用率不低于90%的同时使负载平衡约束满足率达96.07%以上。     

海铁联运港口混合作业模式下轨道吊与集卡协同调度

在集装箱海铁联运港口中,铁路作业区作为连接铁路运输和水路运输的重要节点,其装卸效率将影响集装箱海铁联运的整体效率。首先,对比分析了“船舶-列车”作业模式和“船舶-堆场-列车”作业模式的特点,并结合海铁联运港口实际作业情况提出了混合作业模式。然后,以轨道吊完工时间最短为目标构建混合整数规划模型,既考虑了班列和船舶的作业时间窗约束,又考虑了轨道吊间干扰和安全距离、轨道吊和集卡接续作业和等待时间等现实约束。针对遗传算法在局部搜索能力方面的不足,将启发式规则与遗传算法相结合设计了求解轨道吊与集卡协同调度问题的混合遗传算法（HGA）,并进行了数值实验。实验结果验证了所提模型和混合算法的有效性。最后通过设计实验分析集装箱数量、岸边箱占比、轨道吊数量和集卡数量对轨道吊完工时间和集卡完工时间的影响,发现同等集装箱数量下岸边箱占比提高时,应通过增加轨道吊数量来有效缩短完工时间。     

The Quay Crane Scheduling Problem

The recent growth in worldwide container terminals’ traffic resulted in a crucial need for optimization models to manage the seaside operations and resources. Along with the recent increase in ship size and the container volume, the advancements in the field of Quay Crane Scheduling introduced the need for new modeling approaches. This is the motivation behind the current paper, which focuses on developing a novel yet simple formulation to address the Quay Crane Scheduling Problem (QCSP). The objective of the problem is to determine the sequence of discharge operations of a vessel that a set number of quay cranes will perform so that the completion time of the operations is minimized. The major contribution is attributed to the way that minimization is performed, which is by minimizing the differences between the container loads stacked over a number of bays and by maintaining a balanced load across the bays. Furthermore, important considerations are taken into account, such as the bidirectional movement of cranes and the ability to travel between bays even before completion of all container tasks. These realistic assumptions usually increase model complexity; however, in the current work this is offset by the novel simple objective. This paper presents a mixed-integer programming (MIP) formulation for the problem, which has been validated through multiple test runs with different parameters. Results demonstrate that the problem is solved extremely efficiently, especially for small problem sizes.     

Three-dimensional container loading models with cargo stability and load bearing constraints

Mathematical models for the problem of loading rectangular boxes into containers, trucks or railway cars have been proposed in the literature, however, there is a lack of studies which consider realistic constraints that often arise in practice. In this paper, we present mixed integer linear programming models for the container loading problem that consider the vertical and horizontal stability of the cargo and the load bearing strength of the cargo (including fragility). The models can also be used for loading rectangular boxes on pallets where the boxes do not need to be arranged in horizontal layers on the pallet. A comprehensive performance analysis using optimization software with 100s of randomly generated instances is presented. The computational results validate the models and show that they are able to handle only problems of a moderate size. However, these models might be useful to motivate future research exploring other solution approaches to solve this problem, such as decomposition methods, relaxation methods, heuristics, among others.     

Integrated intelligent techniques for remarshaling and berthing in maritime terminals

Maritime container terminals are facilities where cargo containers are transshipped between ships or between ships and land vehicles (trucks or trains). These terminals involve a large number of complex and combinatorial problems. Two important problems are the container stacking problem and the berth allocation problem. Both problems are generally managed and solved independently but there exist a relationship that must be taken into account to optimize the whole process. The terminal operator normally demands all containers bound for an incoming vessel to be ready in the terminal before its arrival. Similarly, customers (i.e., vessel owners) expect prompt berthing of their vessels upon arrival. This is particularly important for vessels from priority customers who may have been guaranteed berth-on-arrival service in their contract with the terminal operator. To this end, both problems must be interrelated.In this paper, a set of artificial intelligence based-techniques for solving both problems is presented. We develop a planning technique for solving the container stacking problem and a set of optimized allocation algorithms for solving the berth allocation problem independently. Finally we have developed an architecture to solve both problems in an integrated way. Thus, an algorithm for solving the berth allocation problem generates an optimized order of vessels to be served meanwhile our container stacking problem heuristics calculate the minimum number of reshuffles needed to allocate the containers in the appropriate place for the obtained ordering of vessels. Thus combined optimal solutions can be calculated and the terminal operator could decide which solution is more appropriate in each case. These techniques will minimize disruptions and facilitate planning in container terminals.     

An advanced cargo handling system operating at sea

Mobile Harbor (MH) was recently proposed by KAIST as a novel maritime cargo transfer system that can go out to a container ship anchored in deep water and handle containers at sea. Since the system operates in at-sea conditions with waves and wind, the MH crane should be designed to suppress the swing motion of a spreader and compensate the relative motion between the MH and a container ship. For that purpose, we devised a state-of-the-art crane system equipped with a dual stage trolley, tension controller, and intelligent spreader with 3 degrees of freedom. We also integrated a robust sensing system to measure remote motions in harsh open-sea condition. With these advanced systems, we achieved swing free, position, tilting, and heave control systems for precise and safe cargo transfer. Experimental results with a 1/20 scale MH crane show the feasibility of the proposed system for at-sea cargo transfer.     

A parallel multi-population biased random-key genetic algorithm for a container loading problem

This paper presents a multi-population biased random-key genetic algorithm (BRKGA) for the single container loading problem (3D-CLP) where several rectangular boxes of different sizes are loaded into a single rectangular container. The approach uses a maximal-space representation to manage the free spaces in the container. The proposed algorithm hybridizes a novel placement procedure with a multi-population genetic algorithm based on random keys. The BRKGA is used to evolve the order in which the box types are loaded into the container and the corresponding type of layer used in the placement procedure. A heuristic is used to determine the maximal space where each box is placed. A novel procedure is developed for joining free spaces in the case where full support from below is required. The approach is extensively tested on the complete set of test problem instances of Bischoff and Ratcliff [1] and Davies and Bischoff [2] and is compared with 13 other approaches. The test set consists of 1500 instances from weakly to strongly heterogeneous cargo. The computational experiments demonstrate that not only the approach performs very well in all types of instance classes but also it obtains the best overall results when compared with other approaches published in the literature.     

Conceptual and basic designs of the Mobile Harbor crane based on topology and shape optimization

The Mobile Harbor (MH) has been recently proposed as a novel maritime cargo transfer system that can move to a container ship anchored in the deep sea and handle containers directly at sea with the aid of a stabilized MH crane. Because this system operates under at-sea conditions, the MH crane must be designed to support an inertia load and wind force, as well as its self-weight. The wave-induced motions of the MH, e.g. rolling, pitching, and heaving, generate a significant amount of inertia load, which has not been considered in the design of conventional quayside cranes installed on stable ground. Wind force is also a critical design factor due to the higher wind velocity in the open sea. In addition to the aforementioned structural rigidity, mass minimization is also important in the structural design of MH cranes because it reduces the overturning moment and therefore enhances ship stability. In this paper, the sensitivities of the design-dependent loads (i.e. self-weight, inertia load, and wind force) are derived with respect to the design variables, and then a topology optimization is conducted with the derived sensitivities in order to obtain a conceptual design. Then, the conceptual design is elaborated into a three-dimensional basic design through shape optimization with design regulations for offshore cranes. Through the integrated design process with the topology and shape optimizations, a conceptual and basic design is successfully obtained for the MH crane.     

A hybrid differential evolution algorithm for multiple container loading problem with heterogeneous containers

We consider a multiple container loading problem, commonly known as the three-dimensional bin packing problem (3D-BPP), which deals with maximizing container space utilization while the containers available for packing are heterogeneous, i.e., varying in size. The problem has wide applications in cargo transportation, warehouse management, medical packaging, and so on. We develop a differential evolution (DE) algorithm hybridized with a novel packing heuristic strategy, best-match-first (BMF), which generates a compact packing solution based on a given box packing sequence and a container loading sequence. The effectiveness of the proposed algorithm is evaluated on a set of industrial instances and randomly generated instances. The results show that the proposed algorithm outperforms existing solution approaches in terms of solution quality.     

A heuristic for retrieving containers from a yard

This paper presents a three-phase heuristic to solve for an optimized working plan for a crane to retrieve all the containers from a given yard according to a given order. The optimization goal is to minimize the number of container movements, as well as the crane's working time. After generating an initial feasible movement sequence, the second phase reduces the length of the sequence by repeatedly formulating and generating a binary integer program. With another mixed integer program, phase three reduces the crane's working time by adjusting the movement sequence through iterations. Numerical testing results show that the heuristic is able to solve instances with more than 700 containers, which is within the range of real-world applications. Moreover, the number of movements approaches the lower bound in most cases, and the resulting movement sequence is efficient.     

The air-cargo consolidation problem with pivot weight: Models and solution methods

In the international air cargo business, freight is usually consolidated into containers, called Unit Load Devices (ULDs). The transportation charge of a ULD depends on whether the total weight exceeds a certain threshold, called the pivot weight. If the total load tendered by a freight forwarder is less than the pivot weight, it gets charged at the under-pivot rate. Any portion of the load that exceeds the pivot weight is charged at the over-pivot rate. This scheme is adopted for safety reasons to avoid the overloading of ULDs. We formulate a mixed integer program, and propose four solution methodologies for the air-cargo consolidation problem under the pivot-weight scheme (ACPW). These are exact solution approaches based on branch-and-price, a best-fit decreasing loading heuristic, and two extended local branching heuristics (a multi-local tree search and a relaxation-induced neighborhood search). The local branching heuristic with relaxation-induced neighborhood search is found to outperform other approaches in terms of solution quality and computational time. Problems with up to 400 shipments and 80 containers are solved to within 3.4% of optimality in less than 20 min.     

Scheduling of collaborative operations of yard cranes and yard trucks for export containers using hybrid approaches

Optimizing collaborative operations for yard cranes (YCs) and yard trucks (YTs) is vital to the overall performance of a container terminal. This research investigates four different hybrid approaches developed for dealing with yard crane scheduling problem (YCSP) and yard truck scheduling problem (YTSP) simultaneously for export containers in the yard side area of a container terminal. First, these approaches use a load-balancing heuristic to assign containers to YCs evenly. Following this, each of them employs a specific heuristic/metaheuristic, such as genetic algorithm (GA), particle swarm optimization (PSO) or subgroups PSO (SGPSO), to generate alternative container loading sequences for each YC. Finally, a simulation model is used to simulate loading and transporting of these export containers, evaluate alternative planning results, and finally output the best planning result. Experiments have been conducted to compare these hybrid approaches. The results show Hybrid4 (SGPSO) outperforms Hybrid1 (Sort-by-bay), Hybrid2 (GA), and Hybrid3 (PSO) in terms of makespan.     

Design of liquid container handles in accordance with user preferences

In this study, a prototype liquid container combined with auxiliary handles was designed to increase the safety of manual handling and to protect users of these containers from hand contamination. A Likert summated rating method as well as a pairwise ranking test was applied to evaluate the user preferences for handles provided for the container under the conditions of different shapes and positions. The results show that the participants preferred perpendicular orientation of the handle on the top of the liquid container while carrying the containers and the crosswise position of the handle at the side of the container while pouring the liquid. In order to satisfy both conditions, the container needs to be designed with handles in perpendicular as well as crosswise positions for selective application. A prototype liquid container with provided auxiliary handles was developed based on the results of the evaluation. It is recommended that a liquid container provides extra handles to reduce musculoskeletal stress and in turn increase user satisfaction.     

Effect of a redesigned two-wheeled container for refuse collecting on mechanical loading of low back and shoulders

The objective of this study was to compare the mechanical and perceived workload when working with a redesigned two-wheeled container and working with a standard two-wheeled container for refuse collecting. The three changes in the design of the container were a displacement of the position of the centre of mass in the direction of the axis of the wheels, a slight increase in the height of the handle and a slight increase in the horizontal distance between the handle and the wheel-axis, and an increase in the diameter of the wheels. The volume of the container remained 0.240 m3. Nine refuse collectors performed some of their most frequent daily activities with both types of containers in the laboratory. Kinematics and exerted hand forces were assessed as input for detailed 3D biomechanical models of the low back and shoulder to estimate net moments at the low back and shoulders, compressive forces at the low back and contact forces at the glenohumeral joint. Also, the refuse collectors rated the ease of handling the two-wheeled containers on a five point scale. The use of the redesigned container resulted in a decrease of the exerted hand forces of 27%, decreases in the net moments at the low back and shoulders of 8% and 20%, respectively, and a decrease of 32% of the contact force at the glenohumeral joint when compared to the standard container. However, pulling an empty redesigned container on to the pavement resulted in an increase of the shoulder moment of more than 100%. No differences between container types were found for the compressive forces at the low back. Pushing and pulling with the redesigned container was rated as easier than pushing and pulling with the standard container. No differences in subjective ratings were found for the tasks of turning the container or pulling an empty container onto the pavement. It is concluded that, provided that empty containers are placed back onto the pavement as infrequently as possible, the introduction of the redesigned container could result in a reduction of the low back and shoulder load for refuse collectors.     

Design of liquid container handles in accordance with user preferences

In this study, a prototype liquid container combined with auxiliary handles was designed to increase the safety of manual handling and to protect users of these containers from hand contamination. A Likert summated rating method as well as a pairwise ranking test was applied to evaluate the user preferences for handles provided for the container under the conditions of different shapes and positions. The results show that the participants preferred perpendicular orientation of the handle on the top of the liquid container while carrying the containers and the crosswise position of the handle at the side of the container while pouring the liquid. In order to satisfy both conditions, the container needs to be designed with handles in perpendicular as well as crosswise positions for selective application. A prototype liquid container with provided auxiliary handles was developed based on the results of the evaluation. It is recommended that a liquid container provides extra handles to reduce musculoskeletal stress and in turn increase user satisfaction.     

High-performance docker integration scheme based on OpenStack

As an emerging technology in cloud computing Docker is becoming increasingly popular due to its high speed high efficiency and portability. The integration of Docker with OpenStack has been a hot topic in research and industrial areas e.g. as an emulation platform for evaluating cyberspace security technologies. This paper introduces a high-performance Docker integration scheme based on OpenStack that implements a container management service called Yun. Yun interacts with OpenStack’s services and manages the lifecycle of the container through the Docker Engine to integrate OpenStack and Docker. Yun improves the container deployment and throughput as well as the system performance by optimizing the message transmission architecture between internal components the underlying network data transmission architecture between containers and the scheduling methods. Based on the Docker Engine API Yun provides users with interfaces for CPU memory and disk resource limits to satisfy precise resource limits. Regarding scheduling Yun introduces a new NUMA-aware and resource-utilization-aware scheduling model to improve the performance of containers under resource competition and to balance the load of computing resources. Simultaneously Yun decouples from OpenStack versions by isolating its own running environment from the running environment of OpenStack to achieve better compatibility. Experiments show that compared to traditional methods Yun not only achieves the integration of OpenStack and Docker but also exhibits high performance in terms of deployment efficiency container throughput and the container’s system while also achieving load balancing.

     

AC-HAPE3D：基于强化学习的异形填充算法

在3D打印、快递物流等领域,需要将形状各异的零件或货物在限定的空间中摆放,称为异形填充。给出一种摆放方案,以便将尽可能多的多面体放入给定容器;或者一批物体紧密地摆放,使得占用体积最小,则称为异形填充问题。这是个NP问题,很难高效求解。基于此,研究在一个可变维度的三维容器内摆放给定的一组多面体,使得打包后容器的可变维度最小。并提出一个基于强化学习的算法AC-HAPE3D,利用启发式算法HAPE3D将问题建模为马尔可夫过程,再利用基于策略的强化学习方法 Actor-Critic进行学习。同时用体素来表示容器和多面体,从而简化状态信息的表达,并用神经网络表示价值函数和策略函;为了解决状态信息长度以及动作空间可变的问题,采取遮罩的方法来屏蔽部分输入和输出,并且引入LSTM来处理变长的状态信息。在5个不同的数据集进行的实验表明算法能够取得较好的结果。     

Effect of a redesigned two-wheeled container for refuse collecting on mechanical loading of low back and shoulders

The objective of this study was to compare the mechanical and perceived workload when working with a redesigned two-wheeled container and working with a standard two-wheeled container for refuse collecting. The three changes in the design of the container were a displacement of the position of the centre of mass in the direction of the axis of the wheels, a slight increase in the height of the handle and a slight increase in the horizontal distance between the handle and the wheel-axis, and an increase in the diameter of the wheels. The volume of the container remained 0.240 m³. Nine refuse collectors performed some of their most frequent daily activities with both types of containers in the laboratory. Kinematics and exerted hand forces were assessed as input for detailed 3D biomechanical models of the low back and shoulder to estimate net moments at the low back and shoulders, compressive forces at the low back and contact forces at the glenohumeral joint. Also, the refuse collectors rated the ease of handling the two-wheeled containers on a five point scale. The use of the redesigned container resulted in a decrease of the exerted hand forces of 27%, decreases in the net moments at the low back and shoulders of 8% and 20%, respectively, and a decrease of 32% of the contact force at the glenohumeral joint when compared to the standard container. However, pulling an empty redesigned container on to the pavement resulted in an increase of the shoulder moment of more than 100%. No differences between container types were found for the compressive forces at the low back. Pushing and pulling with the redesigned container was rated as easier than pushing and pulling with the standard container. No differences in subjective ratings were found for the tasks of turning the container or pulling an empty container onto the pavement. It is concluded that, provided that empty containers are placed back onto the pavement as infrequently as possible, the introduction of the redesigned container could result in a reduction of the low back and shoulder load for refuse collectors.