Scheduling cross-docking operations under uncertainty: A stochastic genetic algorithm based on scenarios tree

A cross-docking terminal enables consolidating and sorting fast-moving products along supply chain networks and reduces warehousing costs and transportation efforts. The target efficiency of such logistic systems results from synchronizing the physical and information flows while scheduling receiving, shipping and handling operations. Within the tight time-windows imposed by fast-moving products (e.g., perishables), a deterministic schedule hardly adheres to real-world environments because of the uncertainty in trucks arrivals. In this paper, a stochastic MILP model formulates the minimization of penalty costs from exceeding the time-windows under uncertain truck arrivals. Penalty costs are affected by products' perishability or the expected customer’ service level. A validating numerical example shows how to solve (1) dock-assignment, (2) while prioritizing the unloading tasks, and (3) loaded trucks departures with a small instance. A tailored stochastic genetic algorithm able to explore the uncertain scenarios tree and optimize cross-docking operations is then introduced to solve scaled up instaces. The proposed genetic algorithm is tested on a real-world problem provided by a national delivery service network managing the truck-to-door assignment, the loading, unloading, and door-to-door handling operations of a fleet of 271 trucks within two working shifts. The obtained solution improves the deterministic schedule reducing the penalty costs of 60%. Such results underline the impact of unpredicted trucks’ delay and enable assessing the savings from increasing the number of doors at the cross-dock

Cross-Docking: A Proven LTL Technique to Help Suppliers Minimize Products\u27 Unit Costs Delivered to the Final Customers

This study aims at proposing a decision-support tool to reduce the total supply chain costs (TSCC) consisting of two separate and independent objective functions including total transportation costs (TTC) and total cross-docking operating cost (TCDC). The full-truckload (FT) transportation mode is assumed to handle supplier→customer product transportation; otherwise, a cross-docking terminal as an intermediate transshipment node is hired to handle the less-than-truckload (LTL) product transportation between the suppliers and customers. TTC model helps minimize the total transportation costs by maximization of the number of FT transportation and reduction of the total number of LTL. TCDC model tries to minimize total operating costs within a cross-docking terminal. Both sub-objective functions are formulated as binary mathematical programming models. The first objective function is a binary-linear programming model, and the second one is a binary-quadratic assignment problem (QAP) model. QAP is an NP-hard problem, and therefore, besides a complement enumeration method using ILOG CPLEX software, the Tabu search (TS) algorithm with four diversification methods is employed to solve larger size problems. The efficiency of the model is examined from two perspectives by comparing the output of two scenarios including; i.e., 1) when cross-docking is included in the supply chain and 2) when it is excluded. The first perspective is to compare the two scenarios’ outcomes from the total supply chain costs standpoint, and the second perspective is the comparison of the scenarios’ outcomes from the total supply chain costs standpoint. By addressing a numerical example, the results confirm that the present of cross-docking within a supply chain can significantly reduce total supply chain costs and total transportation costs

Supply Chain Management and Management Science: A Successful Marriage

The last century has witnessed extant studies on the applications of Management Science (MS) to a diverse set of Supply Chain Management (SCM) issues. This paper provides an overview of the contribution of MS within SCM. A framework is developed in this paper with a sampling of MS contributions to major SCM dimensions. Future research directions are presented

Cross-docking with vehicle routing problem. A state of art review 1

Este artículo presenta una revisión al estado del arte durante los últimos diez años, de la literatura relacionada con las plataformas de intercambio logísticas, denominadas Cross-Docking. Este tipo de sistemas surgen como alternativa para reducir el costo logístico y el tiempo de respuesta al cliente. El objetivo consiste en simplificar algunos procesos tales como almacenamiento y manejo de materiales, a partir de la reducción de períodos de bodegaje y realización de surtida de materiales en los muelles de ingreso y salida de mercancía. En la primera parte, se desarrolla el concepto, su funcionamiento operativo y clasificación. En la segunda parte, se realiza un reporte de los trabajos más relevantes acerca de esta técnica. Posteriormente, se profundiza en este tema y el ruteo de vehículos simultáneos, haciendo énfasis en los métodos de solución, puesto que se trata de un problema de optimización combinatoria, clasificado como de alta complejidad computacional. Al final, se presentan conclusiones y la discusión.This article reviews the state of the art for the last ten years about the literature related to Cross-Docking. The Cross-Docking systems emerge as an alternative to reduce logistics costs and customer response time in some processes such as warehousing and material handling, times by reducing storage and picking, on the docks of inbound and outbound of vehicles. In the first part, the concept of Cross-Docking is developed, also its operating performance and classification. In the second part, a report on the most relevant works is done. Subsequently, it delves into the issue of vehicle routing and Cross-Docking with emphasis on methods of solution, since it is a combinatorial optimization problem classified as NP-hard. The document ends with the conclusions and discussion

A Cross-Docking Approach for Farfetch Global Delivery

Farfetch is an e-commerce platform with a exponential growth in the last years, but this company has a particular type of business. Farfetch does not hold stock, everything that its sold on farftech.com comes from partners, that are boutiques spread all over the world, that sell high-end fashion articles, that do not have an online presence and relay on Farfetch to have a global reach. When a client buys on ff.com, if more than one item is purchased, they can come from different boutiques placed in different points, for instance, one can belong to a Portuguese partner, and the other can be shipped from an Italian boutique. When this happens, the client will receive two different boxes, arriving at different times, with different tracking information, and this has a huge impact on the client satisfaction and the need to improve the client satisfaction originate the theme for this dissertation. The main objective of this thesis is building a cross-docking strategy to gain knowledge about this strategy, that is something new in the company, identifying the variables with the most impact in cross-docking, and what are Farfetch's limitations on implementing this type of logistics strategy. The project will study this approach to two different markets, one for the Chinese Market, and the second will be a Transatlantic Bridge between Europe and the United States of America. To develop this strategy the software used is AnyLogic, a simulation tool based on agents and discrete-time events, that allow simulating not only the operations inside the cross-dock but also control every agent involved in the process, for example, the operators

Energy and Carbon Dioxide Impacts from Lean Logistics and Retailing Systems: A Discrete-event Simulation Approach for the Consumer Goods Industry

abstract: Consumer goods supply chains have gradually incorporated lean manufacturing principles to identify and reduce non-value-added activities. Companies implementing lean practices have experienced improvements in cost, quality, and demand responsiveness. However certain elements of these practices, especially those related to transportation and distribution may have detrimental impact on the environment. This study asks: What impact do current best practices in lean logistics and retailing have on environmental performance? The research hypothesis of this dissertation establishes that lean distribution of durable and consumable goods can result in an increased amount of carbon dioxide emissions, leading to climate change and natural resource depletion impacts, while lean retailing operations can reduce carbon emissions. Distribution and retailing phases of the life cycle are characterized in a two-echelon supply chain discrete-event simulation modeled after current operations from leading organizations based in the U.S. Southwest. By conducting an overview of critical sustainability issues and their relationship with consumer products, it is possible to address the environmental implications of lean logistics and retailing operations. Provided the waste reduction nature from lean manufacturing, four lean best practices are examined in detail in order to formulate specific research propositions. These propositions are integrated into an experimental design linking annual carbon dioxide equivalent emissions to: (1) shipment frequency between supply chain partners, (2) proximity between decoupling point of products and final customers, (3) inventory turns at the warehousing level, and (4) degree of supplier integration. All propositions are tested through the use of the simulation model. Results confirmed the four research propositions. Furthermore, they suggest synergy between product shipment frequency among supply chain partners and product management due to lean retailing practices. In addition, the study confirms prior research speculations about the potential carbon intensity from transportation operations subject to lean principles.Dissertation/ThesisPh.D. Sustainability 201

E-Fulfillment and Multi-Channel Distribution – A Review

This review addresses the specific supply chain management issues of Internet fulfillment in a multi-channel environment. It provides a systematic overview of managerial planning tasks and reviews corresponding quantitative models. In this way, we aim to enhance the understanding of multi-channel e-fulfillment and to identify gaps between relevant managerial issues and academic literature, thereby indicating directions for future research. One of the recurrent patterns in today’s e-commerce operations is the combination of ‘bricks-and-clicks’, the integration of e-fulfillment into a portfolio of multiple alternative distribution channels. From a supply chain management perspective, multi-channel distribution provides opportunities for serving different customer segments, creating synergies, and exploiting economies of scale. However, in order to successfully exploit these opportunities companies need to master novel challenges. In particular, the design of a multi-channel distribution system requires a constant trade-off between process integration and separation across multiple channels. In addition, sales and operations decisions are ever more tightly intertwined as delivery and after-sales services are becoming key components of the product offering.Distribution;E-fulfillment;Literature Review;Online Retailing