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

Integrating Dock-Door Assignment and Vehicle Routing in Cross-Docking

Cross-docking is a logistic strategy in which products arrive at terminals, are handled and then shipped to the corresponding destinations. Cross-docking consists of unloading products from inbound trucks and loading these products directly into outbound trucks with little or no storage in-between. Cross-docking aims to reduce or eliminate inventory by achieving an efficient synchronization of unloading trucks, material handling and loading trucks. This thesis introduces an integrated dock-door assignment and vehicle routing problem that consists of assigning a set of origin points to inbound doors at the cross-dock, consolidating commodities in-between inbound and outbound doors, and routing vehicles from outbound doors to destination points. The objective is to minimize the sum of the material handling cost at the cross-dock and the transportation cost for routing the commodities to their destinations. Five mixed integer programming formulations are presented and computationally compared. A column generation algorithm based on a set partitioning formulation is developed to obtain lower bounds on the optimal solution value. In addition, a heuristic algorithm is used to obtain upper bounds. Computational experiments are performed to assess the performance of the proposed MIP formulations and solution algorithms on a set of randomly generated instances

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

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

Simulation in Automated Guided Vehicle System Design

The intense global competition that manufacturing companies face today results in an increase of product variety and shorter product life cycles. One response to this threat is agile manufacturing concepts. This requires materials handling systems that are agile and capable of reconfiguration. As competition in the world marketplace becomes increasingly customer-driven, manufacturing environments must be highly reconfigurable and responsive to accommodate product and process changes, with rigid, static automation systems giving way to more flexible types. Automated Guided Vehicle Systems (AGVS) have such capabilities and AGV functionality has been developed to improve flexibility and diminish the traditional disadvantages of AGV-systems. The AGV-system design is however a multi-faceted problem with a large number of design factors of which many are correlating and interdependent. Available methods and techniques exhibit problems in supporting the whole design process. A research review of the work reported on AGVS development in combination with simulation revealed that of 39 papers only four were industrially related. Most work was on the conceptual design phase, but little has been reported on the detailed simulation of AGVS. Semi-autonomous vehicles (SA V) are an innovative concept to overcome the problems of inflexible -systems and to improve materials handling functionality. The SA V concept introduces a higher degree of autonomy in industrial AGV -systems with the man-in-the-Ioop. The introduction of autonomy in industrial applications is approached by explicitly controlling the level of autonomy at different occasions. The SA V s are easy to program and easily reconfigurable regarding navigation systems and material handling equipment. Novel approaches to materials handling like the SA V -concept place new requirements on the AGVS development and the use of simulation as a part of the process. Traditional AGV -system simulation approaches do not fully meet these requirements and the improved functionality of AGVs is not used to its full power. There is a considerflble potential in shortening the AGV -system design-cycle, and thus the manufacturing system design-cycle, and still achieve more accurate solutions well suited for MRS tasks. Recent developments in simulation tools for manufacturing have improved production engineering development and the tools are being adopted more widely in industry. For the development of AGV -systems this has not fully been exploited. Previous research has focused on the conceptual part of the design process and many simulation approaches to AGV -system design lack in validity. In this thesis a methodology is proposed for the structured development of AGV -systems using simulation. Elements of this methodology address the development of novel functionality. The objective of the first research case of this research study was to identify factors for industrial AGV -system simulation. The second research case focuses on simulation in the design of Semi-autonomous vehicles, and the third case evaluates a simulation based design framework. This research study has advanced development by offering a framework for developing testing and evaluating AGV -systems, based on concurrent development using a virtual environment. The ability to exploit unique or novel features of AGVs based on a virtual environment improves the potential of AGV-systems considerably.University of Skovde. European Commission for funding the INCO/COPERNICUS Projec