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1.
以流利式货架分区拣选系统为背景,考虑减小相邻拣选区域的作业时间差值以减少任务在缓存区中的滞留时间和拣货员在系统中的等待时间。建立以最小化订单分批数量和最小化所有相邻区域作业时间差值之和为目标的数学模型,设计遗传算法求解其订单分批结果及任务释放顺序;从拣货员拣选的便捷性出发,考虑将周转频率较高的货品存放至拣货员最易拣取的层数,提出了分类随机指派方式。案例分析结果表明:该模型结果在所有任务的总完成时间、总滞留时间、平均履行周期和所有拣货员在系统中的总等待时间等指标上均表现良好;分类随机指派方式从根本上减少了总拣货时间,进而缩短了任务的平均履行周期和总完成时间,提高了系统处理效率和订单响应速度。  相似文献   

2.
The Order Batching Problem is an optimization problem belonging to the operational management aspect of a warehouse. It consists of grouping the orders received in a warehouse (each order is composed by a list of items to be collected) in a set of batches in such a way that the time needed to collect all the orders is minimized. Each batch has to be collected by a single picker without exceeding a capacity limit. In this paper we propose several strategies based on the Variable Neighborhood Search methodology to tackle the problem. Our approach outperforms, in terms of quality and computing time, previous attempts in the state of the art. These results are confirmed by non-parametric statistical tests.  相似文献   

3.
Storage assignment is an important decision problem in warehouse operation management. In conventional problem settings of distribution warehouses, stock items are stored in bulk but retrieved in small quantities. Storage assignment methods typically make use of demand attribute information of order quantity, order frequency and correlation between demands. In this paper, we address a different problem in which the request for the same stock items is stochastically recurrent. The problem arises when the items are needed in production and, after production, are returned to warehouses for later reuse. Examples of such items include tooling in factory, books in library and digital objects in data warehouses. Utilizing the recurrent characteristics, a salient recency-based storage assignment policy and an associated cascaded warehouse configuration are proposed and analyzed in this paper. This paper has four parts. In the first part, a model of recurrent demand is described. In the second part, the efficiency of the recency-based policy and a traditional ID-based policy is analyzed. In the third part, a mathematical programming model for optimal configuration of cascaded warehouses is presented. Finally, a case study of hospital visits is presented. This paper concludes with recommendations on cascading and zoning the warehouse for applying the recency-based policy.  相似文献   

4.
并行分区拣货系统储位优化设计   总被引:1,自引:0,他引:1  
主要讨论配送中心并行分区拣货系统的特性,在各分区拣货员拣货速度不同的情况下,提出储位指派算法,通过对品项在各分区间储位的安排以平衡各分区拣货员的作业量;根据拣货作业规则和优化目标,对相关模型及算法进行模拟测试以证明其有效性,为方法的选择与应用提供了依据。  相似文献   

5.
针对需要在多个巷道中移动作业的订单拣选问题,设计了存储仓库布置图的数据结构,通过事先把节点之间的最短距离和最短路线计算出来,然后在求订单中任意两个货位间的最短距离时,借助其邻接节点来求。在此基础上设计了一种混合遗传算法来求解问题,并对每一代的最优个体使用Lin-Kernighan算法进行优化。实验结果表明改进的混合遗传算法所求得的解的质量以及收敛速度都有较大提高。该方法可用于超市、书店等需要拣选设备或人员在多巷道间移动拣选的情况。  相似文献   

6.
Due to development and popularity of the information and automation technologies, the traditional logistics industry gradually implements the automation (e.g., sorters) or semi-automation (e.g., conveyors) techniques to support the picking operation in order to save huge labor cost of distribution centers (DCs). As for the semi-automatic picking system using the conveyor system, one of the critical issues is to appropriately assign the items to be picked to each workstation in the conveyor system in order to balance workload of each workstation and to enhance the overall resource utilization of a DC. Traditionally, the job assignment of a conveyor system is conducted by means of empirical rules or arbitrary decision of the planner and the task is usually time-consuming. As for the job assignment of the conveyor-aided picking system, this study develops a model to generate workload-balanced job assignment suggestions to the planner. In the proposed methodology, the expertise of job assignment for conveyor-aided picking system is extracted via interviews in order to derive the empirical rules for conveyor job assignment. After that, the empirical rules are quantitatively converted into empirical indices and the weights of empirical indices can be determined via the historical job assignment records. On the other hand, based on the items denoted in the picking schedule, the candidate job assignment plans are generated randomly or via the exhaustion method. Afterwards, on the basis of the derived empirical indices and corresponding weights, the optimal assignment plan can be determined. In addition to the job assignment algorithm, this study establishes a job assignment system for the conveyor-aided picking system. A real-world case is also presented to verify performance of the proposed methodology. In summary, the job assignment model proposed in this study can significantly reduce the time required for job planning for the conveyor-aided picking system and enhance applicability of the job assignment plans.  相似文献   

7.
In this paper, we intend to address the value creation of utilizing the Industrial Internet of Things (IIoT)-driven resource synchronization and sharing-based robotic mobile fulfillment system (RMFS) to enhance the overall operational effectiveness and efficiencies during information transfer and synchronization of resources. With the advent of IIoT, a graph theory-based heuristic under the multi-deep RMFS is used for computing the shortest path. A-star, Dijkstra, and genetic heuristic algorithms are applied for comparison. A simulation with a consideration of the different types of collisions is conducted for different algorithms. By providing a new three-tier IIoT architecture which includes the suppliers, RMFS, and the disposal center, a model is developed with different storage location assignment rules and strategies under the particular parties to minimize the operation costs. IIoT enables resource synchronization and information sharing, and the path will be generated under different order scenarios with different algorithms. The results show that different storage assignment rules and strategies may lead to 30% cost differences compared to the company’s current practice with random storage.  相似文献   

8.
9.
基于自动拣选系统中并行拣选策略,提出货物品项分配优化问题,以平衡各拣货区工作量,提高系统拣选效率。该问题可归结为分类数已知的聚类问题。为解决此问题,借鉴了人工拣选系统中解决该问题的动态聚类方法,并针对自动拣选系统的特点做两方面改进:在品项间相似系数表达中考虑了各品项拣选数量的影响;在聚类过程中结合了最大最小蚁群算法(MAX-MIN Ant System,MMAS)。最后对两种聚类方法进行仿真分析,结果证明了改进的聚类方法可更大幅度地提高系统拣选效率。  相似文献   

10.
在人到货订单拣选系统中,客户下达订单后将由拣货员穿梭仓库进行拣选.在仓库的拣选设备容量和拣货人员数量有限制的条件下,研究在线订单分批优化问题,预防订单过早或延迟服务,以最短的时间完成拣货任务.构建考虑最小拣货路径的在线订单分批规划模型,以最小化平均有效订单服务时间.提出一种基于规则的启发式算法来求解模型,其中包含k-m...  相似文献   

11.
Order picking is a time-intensive and costly logistics activity as it involves a high amount of manual work. Prior research has mostly neglected the influence of human factors on the efficiency of order picking systems. This paper develops a mathematical model that investigates the impact of learning and forgetting of a heterogeneous workforce on order picking time and, consequently, on storage assignment decisions. In particular, the paper investigates when to change a storage assignment and when to keep it if learning and forgetting occur among the members of an order picking workforce. The results show that learning and forgetting should be considered in order to achieve a proper planning of storage assignment strategies.  相似文献   

12.
Most of previous studies in picker-to-parts warehousing systems investigated only single-picker operations and are therefore adequate to evaluate order picking efficiency by travel distance as aisle congestion never takes place in such systems. In real world applications, the congestion inevitably occurs when a system has multiple pickers working together within the same region. This paper presents an approximation method based on a GI/G/1 closed queueing network by using self-correcting approximation technique algorithm to evaluate the throughput time of an order picking system with multiple pickers and aisle congestion considerations for different routing policies. The results generated by the proposed method are compared and validated via simulation model using eM-plant simulator for different sizes of warehouses. The results indicate that the approximation method appears to be sufficiently accurate for practical purposes. The sensitivity analysis of the throughput time with respect to order sizes, number of pickers and number of aisles are conducted and the performance of different item storage policies are also evaluated using the proposed approximation model.  相似文献   

13.
在网格存储系统中通常包含各种异构的存储设备节点.基于同构系统的传统数据分配和放置策略并不能针对网格存储系统中异构存储设备的性能差异来进行数据分配,降低了网格存储系统的性能.提出一种自适应的数据分配策略(AD).通过运用基于虚拟磁盘性能的自适应分配策略和自适应的数据副本创建策略,AD能够根据存储设备节点的性能差异有效的进行数据分配.实验证明,自适应的数据分配策略能够充分发挥异构存储设备的性能,有效解决网格存储系统的数据放置不平衡问题,提高网格存储系统的利用率.  相似文献   

14.
Many service systems are appointment-driven. In such systems, customers make an appointment and join an external queue (also referred to as the “waiting list”). At the appointed date, the customer arrives at the service facility and receives service. Important measures of interest include the size of the waiting list as well as the time spent in the waiting list. We develop a model to assess these performance measures. The model may be used to support strategic decisions concerning server capacity (e.g. how often should a server be online, how many customers should be served during each service session, etc.). The model is a vacation model that uses efficient algorithms and matrix analytical techniques to obtain waiting list performance measures.  相似文献   

15.
16.
In this paper, we attempt to present a constant due-date assignment policy in a multi-server multi-stage assembly system. This system is modelled as a queuing network, where new product orders are entered into the system according to a Poisson process. It is assumed that only one type of product is produced by the production system and multi-servers can be settled in each service station. Each operation of every work is operated at a devoted service station with only one of the servers located at a node of the network based on first come, first served (FCFS) discipline, while the processing times are independent random variables with exponential distributions. It is also assumed that the transport times between each pair of service stations are independent random variables with generalised Erlang distributions. Each product's end result has a penalty cost that is some linear function of its due date and its actual lead time. The due date is calculated by adding a constant to the time that the order enters into the system. Indeed, this constant value is decided at the beginning of the time horizon and is the constant lead time that a product might expect between the time of placing the order and the time of delivery. For computing the due date, we first convert the queuing network into a stochastic network with exponentially distributed arc lengths. Then, by constructing an appropriate finite-state continuous-time Markov model, a system of differential equations is created to find the manufacturing lead-time distribution for any particular product, analytically. Finally, the constant due date for delivery time is obtained by using a linear function of its due date and minimising the expected aggregate cost per product.  相似文献   

17.
18.
The pole assignment in a specified disk by state feedback for uncertain delta-operator systems is studied. By making use of algebra Riccati equations, a sufficient and necessary condition of pole assignment for a kind of parameter uncertain delta-operator system in a specified disk by state feedback is presented. And the design method of state feedback controller is also developed.The proposed method can unify some previous rehted results of continuous and discrete time systems into the delta framework. The efficiency of the design method is illustrated by a numerical example.  相似文献   

19.
This paper investigates the dynamic behavior of a service system in terms of the arrival rate in the steady state under the influence of social interactions. Customers are backward looking and rational when making purchasing decisions. Existing customers’ re-purchasing decisions are based on their experienced utility – a function of the average waiting time and their expected utility. Potential customers are attracted through social interactions with existing customers. It is shown that the arrival rate of the system in the steady state can exhibit stability, periodic cycles, or chaos due to the effect of social interactions and customers’ purchasing behavior. Two examples based on an M/M/1 queueing system illustrate the role of social interactions and the effect of service rates on the stability of the arrival rate in the steady state. The result highlights the dynamical complexity of a simple service system under the impact of customers’ behavioral factors, or social interactions. It suggests a new perspective to managing service operations whereby social interactions may play a critical role in the fluctuations of demand.  相似文献   

20.
We present a single queueing model which can be used to analyse queueing systems with service interruptions. The model is based on a diffusion approximation using an instantaneous return process which reflects the particular queueing system under consideration. Applications to queueing systems with preemptive resume priority and breakdowns are given in this paper as well as numerical results showing the accuracy of the approximation.  相似文献   

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