基于“货到人”拣选系统的动态货位分配研究

目的 为了提高“货到人”拣选系统的订单拣选效率，研究了电商仓库货位初始存储状态为非空情况下的商品货位分配问题。方法 考虑货架上现存商品信息、仓库空余货位数、待补货商品和新收入商品信息，提出基于商品关联度的分散存储策略，以极大化货架上所有存储商品的关联度之和为目标构建商品上架与下架的动态货位分配数学模型，并设计贪婪算法，再采用改进粒子群算法对贪婪算法得到的结果进行优化。结果 基于商品关联度的分散存储策略可以减少货架平均搬运次数29.32%左右。结论 与随机分配策略相比，文中提出的货位分配策略能够有效提升整个电商仓储中心的拣选速度。     

面向医药行业冷库的移动式货架仓储系统的货位优化研究

为提高移动式货架仓储系统的拣选效率,降低拣选能耗,对其在医药行业冷库应用中的货位优化问题进行研究。针对移动式货架仓储系统自身作业和医药冷库存储的特点,提出以同一巷道品项相关性最大和拣选能耗最小的策略来实现货位优化,建立多目标优化模型。在基本入侵杂草算法(IWO)基础上,设计了混合离散入侵杂草算法(HDIWO)进行仿真求解,通过引入多种群的思想来保证种群的多样性。在空间扩散阶段,采用自适应变异位数策略,用于初期的全局搜索和后期的局部搜索;在竞争生存之后,引入交叉算子和移民算子,增强种群内和种群之间交流。仿真结果表明,与入侵杂草算法、遗传算法相比,该方法具有更好的收敛性和全局搜索能力,能有效提高移动式货架仓储系统的拣选效率,降低拣选能耗,更适合移动式货架仓储系统的货位优化问题的研究。     

基于二进制粒群的拣选作业优化

目的提高电子标签拣选系统中拣选作业的效率与货位占有率。方法以某电子拣选库为研究对象,提出以订单完成度、货位占有率以及货位聚集度为目标的拣选优化模型。设计基于二进制粒子群算法(BPSO)和遗传算法(GA)的模型求解仿生算法。结果试验及优化结果表明,基于BPSO的电子拣选库订单的完成度、货位占有率以及货位聚集度较遗传算法更高。结论基于二进制粒子群算法求解的优化模型较符合实际的电子拣选库人工拣选作业,同时仓储作业货位的利用率及拣选效率得到了提高。     

基于改进遗传算法的自动拣选系统 拣选位分配建模与优化

针对某自动拣选系统建立了拣选位分配优化模型,以拣选时间模型作为适应度函数,并通过判断海明距离添加一个惩罚函数对遗传算法进行了改进,对算例进行仿真实验,可以得到货位排序优化后,总拣选时间明显降低了27.85%。结果表明,货物拣选位的分配对自动拣选系统的拣选效率有很大的影响。要想降低总拣选时间,提高自动拣选系统的拣选效率,不能只考虑个别种类货物的位置分配,要从全局的方向去考虑。该研究对配送中心如何提高自动拣选系统的效率提供了理论支持。     

一种考虑货位共享效应的Fishbone仓储布局优化方法

以Fishbone仓储布局为基础,针对3种经典存储策略,考虑货位共享效应,以单程平均货物拣选距离最短为目标,建立Fishbone布局仓库设计优化模型,以探讨将货位共享效应考虑在内时,不同存储策略对仓储布局的影响;采用分次逼近策略和动态规划算法确定货物的优化分类及类别边界;设计基于自适应的遗传算法获得最优存储分类下的仓储布局参数,并结合案例实验数据进行仿真分析。结果表明,基于分类存储策略的仓储布局表现优异,所需货位数量少且货物拣选距离短;另外,仓储存储物品的需求差异越大,考虑货位共享效应的优势就越显著,最高可减少37.1%的货物拣选距离。     

医药物流中心人工拣选作业流程优化及仿真

费用高、利润低已经成为制约我国医药物流行业发展的主要瓶颈。因此,研究降低医药物流中心人工拣选占有成本的方法对企业赢利具有重要价值。在对物流中心拣选作业流程及其影响因素分析的基础上,建立了基础模型,分别对巷道数不同拣选条目数相同及巷道数不同拣选条目数不同两种情形采用MATLAB进行了仿真,探讨了分区数与拣选条数之间的关系,并对拣选路径进行了分析,发现：1) 分区优于不分区,一般情况下,分区以2个为宜;2) 当分区超过2个后,拣选时间会逐渐增加;3) 在巷道数和拣选条目一定的情况下,分区越多越好;4) 在巷道超过96时,可以考虑分成3个拆零区。     

多层棋盘格式立体货架及其货位排布算法研究

为了使立体仓库在更高的空间利用率条件下发挥最大的存取效率和服务能力,对现有立体货架的结构和搬运模式进行了分析,由此提出了一种新型多层立体仓库货架模型,即多层棋盘格式(multilayers chessboard based,MCB)立体货架模型.从二维角度看,MCB立体货架的货位排布方式类似于在矩形棋盘格内摆放棋子问题,针对如何实现MCB排布方式进行了货位排布算法研究,给出了问题描述、数学模型、算法设计,并构建了基于单件多品种随机存储的"棋子算法(chess pieces algorithm,CPA)",对其进行实验验证.实验结果显示"棋子算法"能够合理并有效地解决MCB立体货架的货位排布问题.MCB立体货架能够使单件多品种随机存储立体仓库的空间利用率达到75%以上,并且为实现更高的存储效率奠定基础.     

基于改进模拟退火遗传算法的自动化立体仓库 货位优化

针对自动化立体仓库出入库作业量大、品类复杂等特点,对仓库货位展开优化研究,遵循周转率原则、货架稳定原则、关联原则等,构建了提高出库效率、提高货架稳定性、增强货物相关性的货位优化模型。使用传统模拟退火算法、遗传算法与改进模拟退火遗传算法求解模型,得出货位优化结果。对比分析结果证明了在解决货位优化问题时,改进算法比传统基础算法更加有效,能更好地改善自动化立体仓库空间使用率低、拣选效率低、货位摆放混乱的现状。     

基于荷兰式拍卖机制的RMFS货位指派研究

目的对移动机器人拣货系统(RMFS)的货位指派问题进行研究,提出基于荷兰式拍卖机制的货位指派模型来提高RMFS的拣货效率。方法构建荷兰式拍卖模型并按周转率对指定区域的SKU进行逐步调整,以货位指派匹配度为期望指标,实现SKU的需求模式与仓库存储结构之间的合理匹配。结果通过与随机指派模型对比发现,在不同仓库规模、需求偏度、订单规模等情况下,基于荷兰式拍卖的货位指派方法可以使拣货路程下降21.15%、工作时间平均下降20.57%左右。结论与传统指派方法相比,提出的货位指派模型可以大幅度降低RMFS系统的拣货距离和时间,大幅度提升在线零售企业的RMFS的拣货效率。     

固定路径下多阶段货位调整研究

提出固定路径下多阶段货位调整方法,它将传统的货位指派分割为多阶段、小规模的动态货位调整过程,并在拣货过程中进行调整。首先,扩展现有的路径策略,设计了前进和返回交替进行的启发式路径策略。然后,基于动态出货量轮盘赌算法来计算候选商品被选择的概率,在此基础上考虑工作量均衡得到最终货位调整方案。最后,与传统方法进行实证研究,结果表明,在平均订单规模较小和需求偏度较大时,该方法能够有效地提高仓库的拣货效率,并且在大多数情况下,巷道内调整优化效果明显,跨巷道调整适合返回型拣货路径策略。     

The effects of pick density on order picking areas with narrow aisles

The cost and service performance of an order fulfillment center are determined partly by how workers are organized into an order picking system. One common approach is batch picking, in which workers circumnavigate a picking area with other workers, gathering items on a pick list. In some systems with high space utilization, narrow aisles prohibit workers from passing one another when in the same aisle, and this leads to congestion. We build analytical and simulation models of these systems to investigate their behavior under different levels of activity. Among other things, our results suggest that when the system is busier and pick density is high (that is, when workers stop often to make picks) congestion is less of a problem and workers are more productive.     

新型无人仓AutoStore的货物合箱方法研究

目的 为减少AutoStore系统在共同存储策略下的订单处理时间,解决经营品类繁多,但仓储面积有限的企业货物存储问题。方法 提出货物合箱的存储方法,设计关联规则挖掘算法与混沌种子优化算法的混合优化算法进行求解。从机器人翻箱操作、料箱的分配规则、系统布局三方面进行分析,结合AutoStore运作规律,建立以机器人拣货行走距离最短为目标函数的数学模型,通过Apriori算法输出货物热度,输入混沌种子算法,得到储位分配结果,实现联动决策。在基本种子算法的迭代中加入混沌序列,帮助种子避开局部极小值。结果 实例分析表明,货物合箱方法能够显著减少共同存储下AutoStore系统的订单处理时间,缩小与指定存储策略订单处理时间的差距,与粒子群算法和基本种子优化算法相比,混沌种子优化算法的优化效率更高、稳定性更好。结论 文中的研究为经营品类繁多,但仓储面积有限的企业提供了一种更适合的货物存储策略,具有较强的操作性和实际意义。     

Enhancing performance in order picking processes by dynamic storage systems

Increasing productivity and reducing labour cost in order picking processes are two major concerns for most warehouse managers. Particularly picker-to-parts order picking methods lead to low productivity as order pickers spend much of their time travelling along the aisles. To enhance order picking process performance, an increasing number of warehouses adopt the concept of dynamic storage where only those products needed for the current order batch are dynamically stored in the pick area, thereby reducing travel time. Other products are stored in a reserve area. We analyse the stability condition for a dynamic storage system with online order arrivals and develop a mathematical model to derive the maximum throughput a DSS can achieve and the minimum number of worker hours needed to obtain this throughput, for order picking systems with a single pick station. We discuss two applications of dynamic storage in order picking systems with multiple pick stations in series. In combination with simulation modelling, we are able to demonstrate that dynamic storage can increase throughput and reduce labour cost significantly.     

基于NSGA-Ⅱ算法的分区拣选优化

电商背景下的客户订单呈现出多品种、小批量、高频次等特点,给仓库拣选工作带来很大的挑战。为提高拣选效率,在订单完全拆分的分批策略和组合优化的行走策略下,设计了以总服务时间最小、分区工作量平衡度最优和二次分拣效率最高的多目标分区拣选模型。由于3个目标函数之间存在矛盾,设计了NSGA-II算法对多目标优化模型进行求解。通过数值实验,与传统的不拆分订单的分区拣选系统对比,发现在订单批量环境为[1,4]时,分别使总服务时间减少了43.88%,平衡度改善了84.61%,并分析了区域个数、订单总数和订单批量环境对系统效率的影响。     

Enhancing the order picking process through a new storage assignment strategy in forward-reserve area

This paper reexamines the order picking process in a warehouse facing the challenges that e-commerce brings about and which are characterised by a very large number of small sized orders and returns. Implementing effective storage assignment strategies combined with efficient batching, in this context, is very fundamental to keep the warehouse’s responsiveness and order completion times up to the standards. This paper investigates a new storage assignment strategy, initially implemented by a large shoes and footwear wholesaler, to enhance the performance of the order picking process in its warehouses. The impact of this new storage assignment strategy on the performance of the order picking process is analysed via simulation. The performance of the system, measured in terms of total picking time as well as order lead time while taking congestion into account, is compared to the cases where conventional storage assignment strategies are implemented. A full factorial design is set up and the simulation output is statistically analysed. The results of this analysis are reported and thoroughly discussed. Attending to the results, the proposed strategy presents a remarkable potential to shorten total picking travel distances and order completion time and consequently customer satisfaction.     

基于拣货员协同合作的订单拣选策略研究

本文对单区块人工作业系统中多个拣货员在拣货作业过程中发生的拣选堵塞问题展开研究。构建基于协同合作的拣选路径模型,通过交换拣选订单,动态调整拣选路径,减少拣选堵塞的产生。案例分析结果表明,与S型策略相比,协同合作策略在减少拣选堵塞、缩短订单服务时间方面具有明显的优越性。最后,从影响拣选作业效率的可控因素角度进行敏感性分析,了解不同情况下协同合作策略对拣选作业效率优化的具体表现。     

双区型仓库动态拣货策略的设计及路径优化研究

目的 针对双区型仓库,以拣货时间最短为目标函数构建数学模型,进一步提高拣货效率。方法 提出并设计动态货位调整与人工拣货协同作业的动态拣货策略,分别采用GA算法和GASA算法进行最优化求解。结果 GASA算法优于GA算法,拣货单为1张情况下的拣货时间可减少4%;与静态拣货策略相比,拣货单为10张情况下,采用GASA算法时,文中设计动态拣货策略下的拣货时间可减少6%,且随着拣货单数量的增加,拣货时间节约占比越大。结论 GASA算法较GA算法其求解动态拣货路径优化问题更高效、优化结果更好。文中所提动态拣货策略更方便实施,在静态拣货路径优化基础上,可进一步提高拣货效率,且拣货单越多,效果就越显著。     

Separation control on a thick airfoil with multiple slots blowing at small speeds

Summary Using multiple slots blowing at small speeds to efficiently control boundary-layer separation on a thick airfoil is studied. The method of numerically solving the Reynolds averaged Navier-Stokes equations was used for the study. The following results were obtained. For multiple slots blowing at small speeds, the wall jet from each slot does not decay very fast (unlike the single slot blowing at the same momentum rate, the wall jet of which has much larger speed) and the near-wall momentum is continuously reinforced by the blowing slots sequentially located on the airfoil upper surface; as a result, under the same momentum blowing rate, multiple slots blowing at small speeds control the boundary layer separation more effectively than single slot blowing at large speed. Moreover, the power expenditure of multiple slots blowing at small speeds is much smaller than that of single slot case. Therefore, using multiple slots blowing at small speeds, high lift and high efficiency (as measured by equivalent lift-drag ratio) can be achieved at the same time. For the multi-slotted thick airfoil (40 percent thickness, 10 slots) considered in this paper, with the blowing total pressure the same as the free-stream total pressure, high lift (C _L =2.3) and large equivalent lift-drag ratio (almost 40) were realized; with a slightly larger blowing total pressure, even higher lift (C _L =3.2) but slightly smaller equivalent lift-drag ratio (about 36) were obtained.