Cross-docking: State of the art

Cross-docking is a logistics strategy in which freight is unloaded from inbound vehicles and (almost) directly loaded into outbound vehicles, with little or no storage in between. This paper presents an overview of the cross-docking concept. Guidelines for the successful use and implementation of cross-docking are discussed and several characteristics are described that can be used to distinguish between different cross-dock types. In addition, this paper presents an extensive review of the existing literature about cross-docking. The discussed papers are classified based on the problem type that is tackled (ranging from more strategic or tactical to more operational problems). Based on this review, several opportunities to improve and extend the current research are indicated.     

Cross dock scheduling: Classification,literature review and research agenda

At cross docking terminals incoming deliveries of inbound trucks are unloaded, sorted, moved across the dock and finally loaded onto outbound trucks, which immediately leave the terminal towards their next destination in the distribution chain. Accordingly, a cross dock is a consolidation point in a distribution network, where multiple smaller shipments can be merged to full truck loads in order to realize economies in transportation. In this context, the truck scheduling problem, which decides on the succession of truck processing at the dock doors, is especially important to ensure a rapid turnover and on-time deliveries. Due to its high real-world significance, several truck scheduling procedures have been introduced during recent years, which all treat specific cross dock settings. In order to structure and promote scientific progress, this paper introduces a classification of deterministic truck scheduling. With the help of this classification, existing literature is reviewed and future research needs are identified. Moreover, we represent a yet unexplored class of truck scheduling problems which is highly relevant in real-world distribution networks.     

Pre-distribution vs. post-distribution for cross-docking with transshipments

Cross-docking operation is a logistics service mode aims to remove the storage and picking up functions of a warehouse, and coordinate goods loading between delivery vehicles and shipping vehicles. Transshipment is another logistic technique that allows goods to be conveyed from an overstocked store to a nearby understocked store, to avoid backordering or loss of sale. This paper models and analyzes two typical cross-docking operations: pre-distribution cross-docking operations (Pre-C) and post-distribution cross-docking operations (Post-C) when transshipments among retail stores are applied. The different operational performances are investigated and compared. The analytical results show that, considering the inventory cost, transshipment cost and operations cost at the cross-dock, the suitability of Pre-C and Post-C are highly sensitive to operations environment factors such as the uncertainty of demand, the unit operations cost at the cross-dock, and the unit inventory holding and shortage cost.     

The Impact of Wireless Technology on Loading Trucks at an Auto Parts Distribution Center

An intervention was introduced for truck loaders that used wireless vehicle mount computers that included auditory, visual feedback, and immediate data delivery. The implementation reliably reduced pallets from being loaded out of sequence for all outbound trucks in multistop routes. The role of the organizational behavior management (OBM) practitioner in designing work procedure changes using technical solutions, requiring a minimum of training, to accelerate key operational processes was examined.     

Integrated planning of inbound and outbound logistics with a Rich Vehicle Routing Problem with backhauls

This paper addresses the integration of the planning decisions concerning inbound logistics in an industrial setting (from the suppliers to the mill) and outbound logistics (from the mill to customers). The goal is to find the minimum cost routing plan, which includes the cost-effective outbound and inbound daily routes (OIRs), consisting of a sequence of deliveries of customer orders, pickup of a full truck-load at a supplier, and its delivery to the mill. This study distinguishes between three planning strategies: opportunistic backhauling planning (OBP), integrated inbound and outbound planning (IIOP) and decoupled planning (DIOP), the latter being the commonly used, particularly in the case of the wood-based panel industry under study. From the point of view of process integration, OBP can be considered as an intermediate stage from DIOP to IIOP. The problem is modelled as a Vehicle Routing Problem with Backhauls, enriched with case-specific rules for visiting the backhaul, split deliveries to customers and the use of a heterogeneous fleet. A new fix-and-optimise matheuristic is proposed for this problem, seeking to obtain good quality solutions within a reasonable computational time. The results from its application to the wood-based panel industry in Portugal show that IIOP can help to reduce total costs in about 2.7%, when compared with DIOP, due to better use of the delivery truck and a reduction of the number of dedicated inbound routes. Regarding OBP, fostering the use of OIRs does not necessarily lead to better routing plans than DIOP, as it depends upon a favourable geographical configuration of the set of customers to be visited in a day, specifically, the relative distance between a linehaul that can be visited last in a route, a neighboring backhaul, and a mill. The paper further provides valuable managerial insights on how the routing plan is impacted by the values of business-related model parameters which are set by the planner with some degree of uncertainty. Results suggest that increasing the maximum length of the route will likely have the largest impact in reducing transportation costs. Moreover, increasing the value of a reward paid for visiting a backhaul can foster the percentage of OIR in the optimal routing plan.     

Scheduling Truck Arrivals at an Air Cargo Terminal

We consider the scheduling of truck arrivals at an air cargo terminal. By coordinating arrivals of cargo delivery trucks with outbound flight departure schedules, some of the shipments can be transferred directly to the departing flights, while others will be stored at the terminal's storage facility and incur extra handling and storage costs. The objective is to obtain a feasible schedule so as to minimize the total cost of operations. We formulate the problem as a time‐indexed integer program and show that, even with limited number of unloading docks at the terminal, the problem is non‐trivial (NP‐hard in the strong sense). Our solution method includes an exact solution procedure to determine an optimal unloading sequence for the shipments carried by each truck, together with a Lagrangian relaxation‐based heuristic for assigning trucks to truck docks and determining truck arrival times. We conducted computational experiments to test the performance of our solution method. Computational results show that our method can generate near‐optimal solutions efficiently. Our simulation results indicate that the scheduling approach proposed in this paper has the potential to generate significant cost savings over a first‐come, first‐served approach currently used at the air cargo terminal that we observed.     

The benefits of a cross-docking delivery strategy: a supply chain collaboration approach

In this study, two models are developed to co-ordinate both production and distribution in order to reduce the relevant costs in a supply chain. According to the functions of the distribution centre, there is a distinction between an inventory co-ordination point and an inventory storage point. The former is a cross-docking strategy, and the latter is a traditional warehousing strategy. The manufacturer has distinct production processes when co-operating with the distribution centre. Case study analysis is used to illustrate the models developed, in which the following conclusions can be obtained: the cross-docking distribution strategy will result in tremendous savings in the total system cost for the supply chain. This study makes two important contributions to the production, and logistics literature. First, the range of applications was extended by studying a new combinatorial problem that incorporates cross-docking in a supply chain environment. Second, computational performance with cross docking was evaluated. The benefit delivery policy for a distribution centre was found by means of integrating manufacturer production planning and a distribution centre delivery policy.     

A solution framework for the multi-mode resource-constrained cross-dock scheduling problem

In this paper we propose a framework for shift-level container scheduling and resource allocation decisions at a cross-dock facility. The Multi-Mode Resource-Constrained Cross-Dock Scheduling Problem (MRCDSP) approach minimizes material flow and schedules inbound and outbound containers to dock-doors such that the total processing time is minimized subject to the resource constraints at the cross-dock. While container scheduling and resource allocation problems at cross-dock facilities have been studied previously in isolation, our work is the first to consider a complete view of cross-dock operations providing optimal container to dock-door allocation, and a makespan minimizing schedule of containers to the cross-dock. We present a comprehensive framework that includes identification of container clusters to reduce the problem size, a container-to-dock-door assignment algorithm, and a container clusters scheduling model that is solvable for practically sized problems. In a comparative numeric study based on data simulating a cross-dock facility, our approach is shown to outperform current practice, reducing the average time required for processing a set of containers by 37% and reducing the weighted-distance material traveled within the cross-dock by 45%.     

Transformer in navigation: Diverse government roles for open innovation in China's high-speed rail

Based on a longitudinal case study of China's high-speed rail embedded in the emerging economy context, we focus on what role the government plays and how that matters to open innovation (OI) for competitive advantage. By linking the OI literature with the national political institutions literature to motivate our research question, we propose a statist-based OI view to differentiate diverse government roles, investigating how government adopts roles in a combined way to push OI in stages. Our findings suggest that government is an important strategic decision-maker for OI. Specifically, the government plays various roles as commander, protector, cultivator, and intermediator, reflecting state activism derived from national political institutions, to construct institutional-level OI for domestic OI activities, and inbound and outbound OI across national borders. We find government can deliberately and strategically use its diverse roles in a combined way to push OI for competitive advantage through the industrial evolutionary process over time. Our study contributes to the OI literature and integrates the strategic management literature with the study of OI to provide new insights to explain the origins of competitive advantage from the state perspective.     

集装箱码头堆场取箱时间窗优化研究

码头堆场是供装卸船舶存放集装箱的场所,同时也是向货主交接集装箱的地方.由于取箱车辆到达时间的不确定性,码头运营方需要在堆场进行大量的翻箱作业,消耗大量的劳动成本.首先对码头取箱时间窗优化机制进行了说明,构建了码头方补助金函数与车辆方的成本函数,获得了车辆方取箱的到达率函数,进而得到了码头方的翻箱次数公式.然后,描述了集...     

三种运营模式下O2O外卖服务供应链质量努力策略研究

O2O外卖作为"互联网+"时代下的新型餐饮模式，日益受到人们的关注。本文研究的O2O外卖服务供应链由一个O2O外卖平台、一个餐饮商家和一个配送骑手构成。O2O外卖平台决策平台的服务质量努力和服务费用，餐饮商家决策产品价格，骑手决策配送服务质量努力程度，同时会受到来自平台或商家的服务质量激励。通过分析商家配送、平台配送和商家自建平台+配送三种运营模式，分别构建O2O外卖服务供应链成员的利润函数，运用博弈理论，优化得到不同模式下O2O外卖服务供应链成员的最优质量控制策略和最优利润。利用公式推导和对比分析，分别探讨了骑手激励金额上限和市场规模对服务供应链最优策略和最优利润的影响。通过数值仿真，可得结论：服务供应链各成员利润均随着市场规模的增大而增大，随着骑手激励金额上限的增加而先增大后减少。当市场规模较小时，平台配送模式下商家最优利润最大。而当市场规模较大时，商家自建平台+配送模式下商家最优利润最大。     

盗版威胁下信息产品在线销售模式选择研究

针对由信息产品制造商和在线平台组成的在线渠道供应链,将信息产品分为传统版本和数字版本,考虑数字盗版的威胁,构建了三种在线渠道合作模式：单一传统版本模式(S模式)、双版本分销模式(W模式)和双版本代销模式(A模式),对比分析了不同模式下在线渠道参与者的利润,力图为在线渠道参与者的决策提供参考。研究发现,若正版与盗版差异较小,或盗版监管力度不足,制造商和在线平台都倾向于采取单一传统版本模式;否则,采取双版本模式更优,当佣金比例适中时,制造商和在线平台在代销模式下可达到双赢。     

A visual planning solution to streamline the processes of hybrid cross-dockings

Cross-docking is a logistic strategy widely adopted both in manufacturing and distribution contexts. Despite the huge number of researches on this topic, most of them remain rather theoretical as they do not pay enough attention to operational aspects and daily functioning patterns of cross-dockings. This article aims at introducing a new focus for cross-docking research by proposing a visual planning solution to manage daily operation of a manufacturing cross-docking. By avoiding complex optimization algorithms and by adopting concepts belonging to the lean management theory, the article shows the potential of visual planning techniques to improve performance of cross-dockings. Starting from a specific industrial context, the shipping warehouse of an Italian company of the oil andand gas sector, a visual management methodology has been proposed to support the operation of cross-dockings. Although developed in a particular context, the proposed methodology and its underlying principles are to be considered general and potentially applicable to a wide range of cross-dockings. The methodology fully exploits an analytical tool, namely, the Safety Margin coefficientthat could be used for capacity planning purposes and to evaluate quantitatively the system performance at a given time instant.     

Pool‐Point Distribution of Zero‐Inventory Products

We study zero‐inventory production‐distribution systems under pool‐point delivery. The zero‐inventory production and distribution paradigm is supported in a variety of industries in which a product cannot be inventoried because of its short shelf life. The advantages of pool‐point (or hub‐and‐spoke) distribution, explored extensively in the literature, include the efficient use of transportation resources and effective day‐to‐day management of operations. The setting of our analysis is as follows: A production facility (plant) with a finite production rate distributes its single product, which cannot be inventoried, to several pool points. Each pool point may require multiple truckloads to satisfy its customers' demand. A third‐party logistics provider then transports the product to individual customers surrounding each pool point. The production rate can be increased up to a certain limit by incurring additional cost. The delivery of the product is done by identical trucks, each having limited capacity and non‐negligible traveling time between the plant and the pool points. Our objective is to coordinate the production and transportation operations so that the total cost of production and distribution is minimized, while respecting the product lifetime and the delivery capacity constraints. This study attempts to develop intuition into zero‐inventory production‐distribution systems under pool‐point delivery by considering several variants of the above setting. These include multiple trucks, a modifiable production rate, and alternative objectives. Using a combination of theoretical analysis and computational experiments, we gain insights into optimizing the total cost of a production‐delivery plan by understanding the trade‐off between production and transportation.     

迈克·德瑞克:TNT中国抢道 在航空货运和零担卡车运输间挖掘空隙市场

大约2/3的并购最终以失败告终,最重要的原因是并购双方的企业文化不能融合今年4月,一箱使用了条形码的货物,被装上了一辆载有GPS定位系统的集装箱货车,驶离了杭州。这意味着全球四大国际快递公司之一的TNT在华全资子公司——天地华宇     

具有时变运输时间的JIT系统批量决策

本文的研究对象是由制造商、配送中心和零售商组成的多级供应链系统,其中零售商要求制造商为其提供短时间间隔、小批量的JIT配送。研究内容为在时变运输时间影响下的供应链系统批量决策问题。在实际运输时间数据的基础上建立了时变运输时间的函数,并以此构建了系统的总成本函数,并在相关文献研究的基础上采用新的更为有效搜索规则进行了求解。根据求解规则,采用ActiveX自动化技术将Matlab的数值计算功能嵌入Visual Basic的集成开发环境中,开发了对应的决策支持系统。最后进行了敏感性分析并提供了低运作成本的决策支持方案。     

电子商务环境下的存储策略优化研究:固定存储还是分类随机存储

库位推荐与拣货过程效率的提升是降低仓库运营成本的两个重要方面。而仓库的存储策略会对仓库运营总成本产生重要影响。本文首先在分类随机存储策略与固定存储策略下构建了库位推荐与拣货路径联合优化的混合整数规划模型;其次,基于快销品行业、医药行业和图书行业下的订单结构特点,采用修正的差分进化算法对两种存储策略进行了对比分析。结论表明：存储策略的优劣不仅与订单结构有关,同时也与单位存储成本与单位拣货成本的比重有关。当比重不高于0.25时,三种行业均是固定存储策略的总成本更低;（2）当比重介于0.25和0.26之间时,快销品行业和医药行业均是固定存储策略的总成本更低,而图书行业下是分类随机存储的成本更低;（3）当比重介于0.26和0.27之间时,快销品行业下是固定存储策略的总成本更低,而图书和医药行业下是分类随机存储的总成本更低。（4）当比重不低于0.27时,三种行业下均是分类随机存储策略的总成本更低。本文可以为不同行业下的仓库存储策略的选择提供一定的参考价值。     

Increasing the Revenue of Self‐Storage Warehouses by Facility Design

Self‐storage is a booming industry. Both private customers and companies can rent temporary space from such facilities. The design of self‐storage warehouses differs from other facility designs in its focus on revenue maximization. A major question is how to design self‐storage facilities to fit market segments and accommodate volatile demand to maximize revenue. Customers that cannot be accommodated with a space size of their choice can be either rejected or upscaled to a larger space. Based on data of 54 warehouses in America, Europe, and Asia, we propose a new facility design approach with models for three different cases: an overflow customer rejection model and two models with customer upscale possibilities, one with reservation and another without reservation. We solve the models for several real warehouse cases, and our results show that the existing self‐storage warehouses can be redesigned to generate larger revenues for all cases. Finally, we show that the upscaling policy without reservation generally outperforms the upscaling policy with reservation.     

Storing Fresh Produce for Fast Retrieval in an Automated Compact Cross‐Dock System

We study temporary storage of fresh produce in a cross‐dock center. In order to minimize cooling cost, compact storage systems are used. A major disadvantage of these systems is that additional retrieval time is needed, caused by necessary reshuffles due to the improper storage sequence of unit loads. In practice therefore, a dedicated storage policy is used in which every storage lane in the system accommodates only one product. However, this policy does not use the planned arrival time information of the outbound trucks. To exploit this information, this study proposes a mathematical model for a shared storage policy that minimizes total retrieval time. The policy allows different products to share the same lane. In order to solve real‐sized problems, an effective and efficient heuristic is proposed, based on a greedy construction and an improvement part, which provides near optimal solutions. The gaps between the results of the heuristic and the lower bound are mostly less than 1%. The resulting shared storage policy is generally robust against disturbances in arrival or departure times. We compare our shared storage heuristic with dedicated storage to determine which policy performs best under which circumstances. For most practical cases, shared storage appears to outperform dedicated storage, with a shorter response time and better storage lane utilization.     

烟草商业企业数字仓库的基本流程与系统功能设计研究

数字仓库的应用将协助企业保证供应、压缩库存、提高货物周转效率、节约成本。本文介绍了数字仓库的概念,研究了烟草商业企业数字仓库的基本流程与系统功能结构与设计,并对数字仓库的效益进行了评价。对这些问题的深入研究将有利于提高烟草商业企业的物流水平和服务效率。