artículos y trabajos publicados

Publicada By  jpgarcia - artículos y trabajos publicados    

A new formulation technique to model materials and operations planning: the generic materials and operations planning (GMOP) problem
Jose P. Garcia-Sabater, Julien Maheut and Juan A. Marin-Garcia

European Journal of Industrial Engineering, 2013, vol. 7, issue 2, pages 119-147

Abstract: This paper presents a technique that mathematically models relationships between operations and materials, which amends the usual technique used to model materials and resources requirement planning through mathematical programming. This technique represents operations and materials requirement planning by extending the bill of materials concept beyond the Gozinto structure. This so-called generic materials and operations planning (GMOP) problem is based on the ‘stroke’ concept. The decision variables are the operations (strokes) each resource is capable of, and not materials or resources. This form extends modelling capacity to transformation operations, resource and product substitution, and material transportation. It considers most conventional bills of materials types (direct, alternative and reverse BOMs, alternative resources and routings) with the same data structure. It contemplates multi-level problem modelling, and even packaging and alternative transport modes. The same data structure represents these characteristics. The problem, its mathematical modelling approach and examples illustrating its use are provided.

1 agosto, 2013

Publicada By  jpgarcia - artículos y trabajos publicados    

Algorithm for complete enumeration based on a stroke graph to solve the supply network configuration and operations scheduling problem

Julien Maheut, Jose P. Garcia-Sabater

Purpose: The purpose of this paper is to present an algorithm that solves the supply network configuration and operations scheduling problem in a mass customization company that faces alternative operations for one specific tool machine order in a multiplant context.

Design/methodology/approach: To achieve this objective, the supply chain network configuration and operations scheduling problem is presented. A model based on stroke graphs allows the design of an algorithm that enumerates all the feasible solutions. The algorithm considers the arrival of a new customized order proposal which has to be inserted into a scheduled program. A selection function is then used to choose the solutions to be simulated in a specific simulation tool implemented in a Decision Support System.

Findings: The algorithm itself proves efficient to find all feasible solutions when alternative operations must be considered. The stroke structure is successfully used to schedule operations when considering more than one manufacturing and supply option in each step.

Research limitations/implications: This paper includes only the algorithm structure for a one-by-one, sequenced introduction of new products into the list of units to be manufactured. Therefore, the lotsizing process is done on a lot-per-lot basis. Moreover, the validation analysis is done through a case study and no generalization can be done without risk.

Practical implications: The result of this research would help stakeholders to determine all the feasible and practical solutions for their problem. It would also allow to assessing the total costs and delivery times of each solution. Moreover, the Decision Support System proves useful to assess alternative solutions.

Originality/value: This research offers a simple algorithm that helps solve the supply network configuration problem and, simultaneously, the scheduling problem by considering alternative operations. The proposed system allows an easier generation of many different alternatives for the supply network configuration.

1 agosto, 2013

Publicada By  jpgarcia - artículos y trabajos publicados    

The Generic Materials and Operations Planning (GMOP) Problem Solved Iteratively: A Case Study in Multi-site Context

Julien MaheutJose P. Garcia-Sabater, Josefa Mula

This paper addresses the Generic Materials and Operations Planning (GMOP) problem, a multi-site operations planning problem based on the “stroke” concept. The problem considers a multinational company subject to positive and negative backlogs imposed by using returnable racks that have to be filled by end products and transported to customers, alternative operations (purchase, transformation and transport), different BOM structures given the different operation types (injection operations, assembly operations) performed in the various factories of the supply chain, and capacitated production resources. This paper describes and defines the “stroke” construct that mathematically models the relationships between operations and materials. The mathematical modelling approach is provided, as is a brief description of an operations planning tool that has been implemented. Furthermore, some results obtained in a first-tier level supplier of the automotive industry have been introduced

1 agosto, 2013

Publicada By  jpgarcia - artículos y trabajos publicados    

A decision support system for modelling and implementing the supply network configuration and operations scheduling problem in the machine tool industry

DOI: 10.1080/09537287.2013.798087
Julien Maheuta*Juan Manuel BesgabJone Uribetxebarriab &Jose P. Garcia-Sabatera
This paper presents a decision support system to simultaneously solve the supply network configuration problem and the operations scheduling problem for the machine tool industry. A novel database structure, which is able to consider alternative operations and alternative bills of material, has been used. An algorithm for complete enumeration to determine all the feasible solutions using stroke graphs is introduced. A multiagent-based simulator evaluates the different key performance indicators that the supply network deals with for each alternative solution (e.g. workload, profits, delivery times, etc.) to determine that ‘satisficed’ by the collaborative decision-making among its members. A case study based on a Spanish company that assembles highly customised machines and tools in several European plants is considered. From the experiments results based on data linked to this industry, it will be demonstrated that the tool is potentially useful for stakeholders and for the central decision-maker to make decisions collaboratively in a multisite context case.
link to pdf
1 agosto, 2013

Publicada By  jpgarcia - artículos y trabajos publicados    

This paper addresses the problem of sequencing for the mixed-model assembly lines in the car industry. In
the real car productive systems, the sequence is defined by the content and the extraction order of a subset of
units, taken from a buffer at the beginning of the assembly line, which is dynamically refilled. The problem
consists of defining the sequence of an assembly line in real time to optimize the flow of materials and the
requirements of resources on the line. Some results obtained with real data from the factory are shown, and
they demonstrate that the heuristic approach performs well in the real productive system where it has been

21 marzo, 2012

Publicada By  jpgarcia - artículos y trabajos publicados    


In this work is it proposed a computational tool for performing production and warehouse budgets in an environment with uncertainty and seasonality. The problem is framed in a multi-product, multi-period and a limited production and storage capacity. It is intended that the generated budget is robust to fluctuations and seasonality of demand subject to the limitations of the system and legal requirements. It is proposed a method that consists of three stages: in the first stage the demand is time-disaggregated; in the second stage objective stock levels are calculated with a fuzzy linear programming model with the aim of providing a long-term vision to the third stage models; the last stage consists of developing the budget structured in a set of scenarios as a consequence of a simulation/optimization in rolling horizon. Finally, it is showed the architecture of the tool and its validation.


20 marzo, 2012

Publicada By  jpgarcia - artículos y trabajos publicados    


Julien Maheut, José P. García-Sabater

(pdf) Publicado en DYO N0 45


La gestión de materiales de productos multi-nivel usa desde los años 1970 la metodología denominada MRP. La incorporación del CRP en los ERP conjuntamente al MRP tradicional dio nacimiento a los llamados MRPII. Sin embargo, desde aquella época en la literatura, se asigna una única lista de materiales y una lista única de recursos a cada producto susceptible de ser ensamblado lo que implica fuertes limitaciones para considerar operaciones alternativas. En el problema GMOP, se propone el uso del concepto del stroke para resolver el problema de planificación de las operaciones y de los materiales considerando operaciones alternativas. En este artículo, se presenta primero una evolución del problema GMOP introduciendo las recepciones programadas, y segundo, se presenta el despliegue y análisis de las matrices que se proponen para facilitar la implementación de un modelo y una herramienta que se basen en el concepto de stroke.

Palabras clave: cadena de suministro, planificación de las operaciones, operaciones alternativas, stroke, MRP, GMOP.

The Operations & Materials Matrix and the Operations & Resources Matrix, a new approach to solve the GMOP problem based on the Stroke concept

Abstract: Since the 1970, the multi-stage product materials management used the methodology called MRP. The CRP incorporation in the traditional ERP jointly with the MRP gave birth to the so-called MRPII. However, since that time in the literature, a unique bill of materials and a unique list of resources are assigned to each product to be assembled which implies strong limitations to consider alternative operations. In the GMOP problem, the use of the stroke concept is proposed to solve the operations and materials planning problem considering alternative operations. The aim of this paper is to present firstly an evolution of the GMOP problem considering scheduled receptions, and secondly to present the deployment and analysis of the matrices that are proposed to facilitate a model and tool implementation based on the stroke concept.

Keywords: supply chain, operations planning, alternative operations, stroke, MRP, GMOP.

7 marzo, 2012

Publicada By  jpgarcia - artículos y trabajos publicados    

Un nuevo capítulo de Libro

A Supply Chain Operations Lot-Sizing and Scheduling Model with Alternative Operations
Julien Maheut, José Pedro Garcia-Sabater and Josefa Mula


10 enero, 2012

Publicada By  jpgarcia - artículos y trabajos publicados, Corsari    

This paper presents an algorithm to define the optimal parameters for deliberated and controlled coproduction in an economic lot scheduling problem setting (DCCELSP). Coproduction is said to be deliberated and controlled because it is possible to decide whether or not to coproduce when all the parameters associated with the process are known. The aim is to determine how to produce two products most economically where deliberated coproduction is an option. For this purpose, a procedure for defining optimal lot periods is introduced. Two models are proposed for this procedure and a numerical illustration is provided to gain insight into their dynamics. The cost advantages of coproduction were found to depend on the relationship between setup and holding costs, production rates, and demand for products. The more similar these system parameters are and the higher the machine usage ratio is, the more favourable coproduction is. Additionally, if coproduction is not deliberated appropriately, costs soar.

Economic lot scheduling with deliberated and controlled coproduction European Journal of Operational Research, Volume 219, Issue 2, 1 June 2012, Pages 396-404

  • Pilar.I. Vidal-CarrerasaCorresponding author contact informationE-mail the corresponding author,
  • Jose P. Garcia-Sabatera,
  • Jairo R. Coronado-Hernandezb

en una revista que no crecerá mucho porque es una de las clásicas

European Journal of Operational Research

9 enero, 2012

Publicada By  jpgarcia - artículos y trabajos publicados    

Un nuevo artículo.

Supply Chain Network Design Optimization

en una revista que sólo puede crecer

Journal Of Marketing and Operations Management Research

16 diciembre, 2011

Universidad Politécnica de Valencia