Re-marshaling export containers in port container terminals

In order to speed up the loading operation of export containers onto a ship, the re-marshaling operation is an usual practice in port container terminals. It is assumed that the current yard map for containers is available and a desirable bay layout is provided. A methodology is proposed to convert the current bay layout into the desirable layout by moving the fewest possible number of containers and in the shortest possible travel distance. The problem is decomposed into three sub-problems such as the bay matching, the move planning, and the task sequencing. The bay matching is to match a specific current bay with a bay configuration in the target layout. In the move planning stage, the number of containers to be moved from a specific bay to another is determined. The completion time of the re-marshaling operation is minimized by sequencing the moving tasks in the final stage. A mathematical model is suggested for each sub-problem. A numerical example is provided to illustrate the solution procedure.     

Computerized container-ship load planning: A methodology and evaluation

A heuristic is developed to plan loads for containerized cargo ships. It is designed to serve a port which uses gantry cranes (transtainers) and trucks to handle containers. The model recognizes constraints on ship stability, placing containers in a bay with the proper length, limits on stack height in under-deck bays, limits on stack weight in on-deck bays, refrigerated containers, and the need for support under a container. Provisions are made for the operator to handle overstowage of cargo for different ports and placement of oversize cargo. The model uses minimization of transtainer movement time and minimization of rehandles in the yard as an objective. The heuristic uses strategies for container placement similar to those used in manual load planning. A test of two ships and four voyages at the Port of Portland produced feasible load plans for each voyage. Transtainer movement and rehandling time varied for the four voyages; but on the average, the heuristic reduced a composite material handling measure by 4.8%.     

自动化码头堆场穿越式双ASC调度

随着人工智能等科技的发展,海铁联运的运输模式加快了集装箱码头自动化的发展进程,自动化已经成为集装箱码头发展的必然趋势。对自动化集装箱码头堆场内可穿越式双自动堆垛起重机（ASC）在同一箱区内进行作业的过程进行研究,考虑不同大小的ASC的运行速度和单位时间内耗能不一样,以及在同一贝位两个ASC存在冲突的情况,建立多目标混合整数模型,得出完成所有集装箱任务的总时间和总耗能。并通过改变不同的参数来设计三组实验,实验结果表明,可以通过调整集装箱任务量、双ASC的速度、双ASC装载和空载的耗能之比来减少码头作业集装箱任务的总时间和总能耗。     

基于网络模型的集装箱预翻箱问题研究

集装箱翻箱问题涉及集装箱装卸工作的顺畅与否。以此为研究对象,首先建立了基于网络模型的集装箱翻箱模型,并用算例进行了计算试验。在此基础上,对约束进行了改正,建立了改正的集装箱预翻箱模型,并进行了计算验证,证明了其在计算时间上的压缩。根据实际的单贝集装箱堆存情况,进行了实际堆存状态翻箱的计算试验,取得了阶段性成果。对单贝集装箱的堆存数与翻箱次数的关系进行了研究,发现在堆存数达到17时有较好的堆场利用率和较少的翻箱次数。     

基于双层规划的容器云资源动态配置算法

本文分析容器云资源动态配置决策问题,通过定义容器云资源的调度任务,求解得到容器云资源调度时间;利用容器云资源调度任务的最短时间矩阵,获取容器云资源调度所需的条件。在双层规划条件下,求解容器云资源调度的目标函数和约束函数;考虑到用户的任务情况和云数据中心的云资源状况,在虚拟机上构建一个到物理主机的矩阵,通过构建容器云资源动态配置结果在优化时的目标函数,结合约束条件,实现容器云资源的动态配置。实验结果表明,资源动态配置算法不仅可以提高容器云资源的利用率,还可以减少配置完成时间,具有更好的动态配置性能。     

求解等球packing 问题的两个策略

为求解等球packing问题,在拟物模型基础上提出两个启发式策略:伪球策略和序列对称换位策略.前者旨在保证获取精确解;后者则用于从局部最优布局出发搜索到紧凑的可行布局.在处理器为Pentium E6500 2.93GHz的PC机上进行了实算.在球形容器内对多达200个等球、在立方体内对多达150个等球进行了紧密装填.结果在质量和算例数量上均显著改进了国际上已知最好记录.特别地,在半径小于5的大球中装下了68个半径为1的等球,证明否定了一个猜想,其认为半径为5的大球最多只能装下67个半径为1的等球.     

A tree search procedure for the container relocation problem

In the container relocation problem (CRP) n items are given that belong to G different item groups (g=1,…,G). The items are piled up in up to S stacks with a maximum stack height H. A move can either shift one item from the top of a stack to the top of another one (relocation) or pick an item from the top of a stack and entirely remove it (remove). A move of the latter type is only feasible if the group index of the item is minimum compared to all remaining items in all stacks. A move sequence of minimum length has to be determined that removes all items from the stacks. The CRP occurs frequently in container terminals of seaports. It has to be solved when containers, piled up in stacks, need to be transported to a ship or to trucks in a predefined sequence. This article presents a heuristic tree search procedure for the CRP. The procedure is compared to all known solution approaches for the CRP and turns out to be very competitive.     

Mechanical loading on the low back in three methods of refuse collecting

The mechanical loading on the low back was studied in three different current methods of refuse collecting: in polythene bags, two-wheeled mini-containers and large four-wheeled containers. To this end the most prominent activities of each collecting method were performed in a laboratory. On the basis of movement analysis, force measurements and biomechanical modelling, spinal compressive and shear forces were estimated. From these forces and from the frequency of activities during the working day (assessed in a preliminary field study) the low-back stress in each collecting method was evaluated. In the bag-method, peak forces when throwing the bags ranged from 3341 to 5179?N (average compression) and from 284 to 673?N (shear) among the different conditions studied. The act of picking up bags also showed rather high forces (exceeding the NIOSH limit for disc compression in most cases). The frequency of exposure to these forces in the field is rather high (workers pick up and throw on average 807 times each day). The mini-container method compares favourably to the bags method. Peak compressive and shear force in tilting/pushing and pulling mini-containers ranged from 1657 to 2654?N and from 123 to 248?N respectively. Also, the frequency of stressful events in the Held is lower in this method. In the large container method extremely high peak forces (e.g. compression ranged from 4991 to 5810N) were observed in the task of putting the empty container back from street level to sidewalk level (surmounting the kerb). The frequency of activities like pushing, pulling and lifting the large container in the field is much lower compared with activities in the other methods. On the basis of the frequency and magnitude of spinal forces it was concluded that the mini-containers should be preferred to the bags. If kerbs are removed at container places and tasks are performed by two instead of a single person, the large container method would form another good alternative to the stressful task of collecting refuse in bags.     

动态环境下集装箱码头堆场出口箱箱位分配建模与算法研究

箱位分配是集装箱码头运作优化管理的关键问题.针对出口箱交箱时间的动态不确定性,提出两级调度策略,将出口箱位分配问题分解为贝位分配和贝内具体箱位分配,分别建立规划模型优化龙门吊大车行使距离和翻箱量,并针对两级调度策略特点分别设计开发基于禁忌搜索的求解算法.模拟实验表明,所提出的方法能够适应动态条件变化,改善调度效果,并在合理时间内获得满意解.     

基于CPLD的锁相位同步信号提取技术

锁相位同步提取技术是通信系统中一个重要的实际问题。现介绍一种用CPLD复杂可编程逻辑器件为控制核心 ,采用AHDL语言编程实现数字锁相位同步信号提取的方法。使整体设计、功能实现更加稳定、可靠。