Scheduling to minimize maximum earliness and number of tardy jobs where machine idle time is allowed

We address the bicriteria problem of minimizing the number of tardy jobs and maximum earliness on a single machine where machine idle time is allowed. We show that the problem of minimizing the number of tardy jobs while maximum earliness is kept at its minimum value of zero is polynomially solvable. We present polynomial time algorithms for the maximum earliness problem subject to no tardy jobs and the maximum earliness problem for a given set of tardy jobs. Finally, we discuss the use of the latter algorithm in generating all efficient schedules

Multi-Period Cell Loading and Job Sequencing in a Cellular Manufacturing System

In this paper, a multi-period cell loading problem is addressed, where the objectives are to minimise the number of tardy jobs (nT) in a multi-period planning horizon and optimise the scheduling of tardy jobs. Three cell loading and job scheduling strategies are proposed and tested with two newly developed mixed integer programming models. Additionally, three types of due dates (tight, medium and loose) and three different demand levels were considered. Finally, two tardy job assignment methods were proposed to observe the impact on nT. Case problems were solved based on minimising nT, Tmax and total tardiness (TT) objectives and cost sensitivity analysis was performed. Results indicated that, the first strategy, (early start allowance and tardy job assignment after each period) performed better in terms of nT. For the secondary objectives, tradeoffs were observed among different strategies depending on the type of due date, demand level and tardy job assignment method

Diseño de una metodología basada en una técnica inteligente para el análisis de los tiempos muertos de una línea de producción. Aplicación en una empresa del sector alimenticio de la zona centro de Colombia

En este trabajo se presenta una metodología basada en una técnica inteligente para analizar las fallas en las diferentes máquinas de una línea de producción, con el fin de establecer e identificar las principales variables que generan la mayor fracción de tiempos muertos en el sistema productivo y plantear posibles soluciones. El desarrollo se realizó en cinco pasos. El primero corresponde a la recolección de la información en una base de datos; el segundo es la estandarización de la descripción de los fallos; el tercero es la aplicación de la minería de datos a partir de la información recolectada; el cuarto es la determinación del modelo matemático a aplicar; el quinto es concluir a partir de los resultados obtenidos. La herramienta utilizada es WEKA con el modelo de árbol de clasificación J48. El resultado de la metodología propuesta en comparación a la metodología actual es positivo, ya que se logra un incremento de 3.58 puntos porcentuales en el indicador de eficiencia global, lo que concluye que la herramienta sirve para identificar y reducir los tiempos muertos de una línea de producciónAbstract : This paper proposed methodology based on an intelligent technique to analyze the failures in the different machines of a production line, in order to establish and identify the main variables that generate the greatest fraction of idle times in the system and to propose possible solutions. The development of the methodology was carried out in five steps. The first corresponds to the collection of information in a database; the second is the standardization of the description of the faults; the third is the application of data mining from the information collected; the fourth is the determination of the mathematical model to be applied; the fifth is to conclude from the results obtained. The tool used was WEKA with the classification tree J48. The result of the proposed methodology in comparison with the current methodology, is positive, because it is achieved increase of 3.58 percentage points is achieved in the overall efficiency indicator, which allows to conclude that the tool is used to identify and reduce the idle times of a line of productionMaestrí