William Sarache

Una Metodología Multiobjetivo para Optimizar un Ambiente Job Shop

The development of a methodology that contains a metaheuristic model based on the Elitist NonDominated Sorting Genetic Algorithm (NSGA-II) in a job shop production environment. This is to minimize three main process variables: total time of processing (makespan time), energy cost and labor accidents. With the application of this methodology, the variables under study were optimized in 42%, compared with traditional production programming techniques. Based on the application of the proposed methodology, it is suggested to explore other multi objective functions in which the consumption of other resources, such as water and fuel can be analyzed in undesirable situations such as transport strike, landslides and traffic congestion.

Aplicación de un Algoritmo Evolutivo en la Solución de Problemas Job Shop-Open Shop

The aim of the work presented in this paper was to reduce makespan time and idle time, and to increase machine utilization, in Job Shop-Open Shop environment, using a new methodology based on evolutionary algorithms. The study was done in an enterprise of the metal-mechanics sector. The proposed methodology is easy to implement and apply and the results are highly consistent, as shown by a variance analysis. The methodology allows reducing the total processing time by 33% and idle time by 51% with 99% approximation with respect to the optimum solution.

Estrategia de Manufactura: Explorando el Contenido y el Proceso

The aim of this article is to explore the content (competitive priorities and strategic decision areas) and the process (pattern of decision making), based on the performance and firm characteristics (size, target market and type). Manufacturing strategy addresses the long-term planning of the production system and the literature has focused on content and few contributions have addressed the simultaneous analysis of these two elements. For this study, an empirical investigation was done by applying a survey in 36 Colombian manufacturing companies. The results showed no significant differences in relation to the analyzed characteristics. However, three clusters of companies were identified according to their performance in competitive priorities. Regarding to the pattern of decision making (top-down, bottom-up, mixed), differences in performance were not identified.

DESIGN OF A HYPERHEURISTIC FOR PRODUCTION SCHEDULING IN JOB SHOP ENVIRONMENTS

El objetivo del presente trabajo es disminuir el tiempo de proceso (Makespan) e incrementar el tiempo de trabajo de las maquinas, diminuyendo el tiempo de ocio en ambientes de Job Shop, a traves del diseno de una Hiper-heuristica basada en colonia de hormigas y algoritmos geneticos. Este trabajo se desarrolla en dos etapas: en la primera se realiza la definicion e identificacion de una Hiper-heuristica para la secuenciacion de procesos en ambientes Job shop. En la segunda etapa, es mostrada la efectividad del sistema en la programacion de la produccion. En el proyecto de investigacion, se selecciono una empresa del sector metalmecanico, donde por medio de una combinacion de colonia de hormigas y algoritmos geneticos, se programa la ruta optima para un pedido, logrando la optimizacion o suboptimizacion de su respectivo tiempo total de proceso en un porcentaje superior al 95%.

A maturity assessment model for manufacturing systems

Assessment of manufacturing systems provides a baseline for manufacturing strategy (MS) formulation. The purpose of this paper is to develop and propose a maturity assessment model for manufacturing systems (MAMMS). The MAMMS provides a maturity index, in order to establish manufacturing system performance on five possible levels: preinfantile, infantile, industry average, adult, and world class manufacturing.,Three main steps were taken: MAMMS design; maturity-level assessment in two companies; and MAMMS validation. Based on an action-research process, several research tools, such as surveys, expert panels, and immersion in two manufacturing companies, were used.,By integrating 79 variables into a maturity index, the maturity level for two manufacturing companies was obtained. Considering three main components (competitive priorities, manufacturing levers, and manufacturing’s strategic role), the analyzed companies showed a performance at the average industry level. According to participants, the MAMMS is a valuable tool to support decision making in MS.,Empirical evidence supports the relevance of the proposed MAMMS and its practical usefulness. In particular, the maturity index identifies strengths and weaknesses in the manufacturing system, providing a baseline from which to deploy MS.,The literature review shows a lack of contributions regarding maturity models, particularly, the non-existence of maturity assessment models for manufacturing systems. The proposed MAMMS is a valuable tool to support decision making in MS. Also, this paper contributes to understanding the action-research paradigm, for further research in operations management.

Identificación y Análisis de una Red de Ayuda Humanitaria: Un Caso de Estudio

espanolCon el proposito de abordar diversos desafios que enfrenta la logistica humanitaria, se identifico la configuracion de la red de ayuda humanitaria de la ciudad de Manizales, Colombia y luego se analizo utilizando la teoria de grafos como componente del analisis de redes sociales. La logistica humanitaria enfrenta varios desafios debido a las circunstancias adversas en las cuales se desarrolla. En particular, la coordinacion entre actores ha sido identificada como uno de los mayores problemas cuando ocurre un desastre. La configuracion de la red permitio determinar la estructura general y algunas caracteristicas particulares de la red objeto estudio. Se identificaron tres actores de relevancia y la existencia de cuatro comunidades dentro de la estructura general de la red. Asi mismo, se evidencio la baja densidad de la red, la cual constituye un aspecto importante a considerar en la formulacion de politicas publicas en torno a las capacidades para la atencion de desastres. EnglishWith the purpose of addressing the several challenges that humanitarian logistics faces, the configuration of the humanitarian aid of Manizales city (Colombia) was identified and graph theory as a component of social network analysis was used. Humanitarian logistics faces these challenges due to adverse circumstances in which it takes place. In particular, coordination between actors has been identified as one of the biggest problems in this field of study. As a result, the overall structure and some particular network characteristics were determined. Also, the three most important actors and the existence of four communities were identified. The low network density was detected as one of the main problems, which constitutes an important aspect to consider in public policy formulation on disaster remediation.

Manufacturing’s Strategic Role and Management Practices: Evidence from Colombian Companies

Operations Strategy (OS) is a long-term plan for Manufacturing/Operations Systems (MOS), oriented toward the generation of distinct organizational advantages. Typically, OS studies have fixated on two components: content and process. However, Manufacturing’s Strategic Role (MSR), despite its importance to MOS performance, has remained as a missing link in the OS field. As such, in the present chapter, MSR is explored, and the management practices adopted by a group of companies located in the Colombian coffee region are analyzed. Survey research is conducted for the verification of MSR influence on MOS performance, and the level of management practices used in manufacturing as well as their relationship with MSR is evaluated. Investigative results permit the conclusion that MSR is a new variable that should be integrated into the OS formulation process. The proposed MSR registered internal consistency and impact on MOS performance; therefore, in this study, MSR is highlighted as a fundamental component of the OS. The case study revealed that manufacturing management practices are different than those typically addressed in the investigative literature. These findings contribute to the advancement of OS study and report empirical evidence from the Colombian context.

Programación de un Sistema Job Shop-Open Shop por medio de una Red Neuronal

espanolSe propone una metodologia basada en redes neuronales para la programacion de pedidos en un ambiente job shop-open shop. El problema de programacion de la produccion en sistemas job shop consiste en definir la mejor secuencia de pedidos para minimizar el tiempo total de proceso (makespan) u otras variables relevantes. Diversas tecnicas inteligentes se han aplicado para resolver este tipo de problema. 2in embargo, estas presentan dificultades practicas cuando se requieren cambios de programacion, pues exigen reconfigurar nuevamente el problema para obtener una nueva solucion. La metodologia propuesta entrena la red mediante la combinacion de los tiempos de proceso en cada nodo, por medio de funciones de transferencia multiplicadas por pesos que son generados por el algoritmo de programacion de la red. La red neuronal propuesta permite obtener soluciones no solo para un problema en particular, sino para los nuevos que surjan sin necesidad de hacer una nueva reconfiguracion. Las soluciones encontradas fueron comparadas con otras tecnicas de programacion de la produccion, encontrandose desempenos superiores en el makespan del orden del 30% al 164%. EnglishA methodology based on neural networks is proposed for solving the job shop-open shop scheduling problem. The job shop scheduling problem consist of defining the best order sequence to minimize the total processing time (makespan) or other relevant variables. 2everal intelligent techniques have been applied to solve this kind of problem. However, when reprogramming is required these techniques present practical difficulties since they require to be restructured to find a new solution. The proposed methodology trains the network by combining the processing times at each node, through transfer functions that are multiplied by weights obtained from the algorithm of network programming. The proposed neural network obtains solutions not only for a particular problem but also for new situations without requiring a problem reconfiguration. When compared with other techniques, the obtained solution showed a superior performance ranging from 30% to 164% in terms of the makespan.

Metodología Integral para el Mejoramiento de la Calidad Mediante la Reducción de la Variabilidad Funcional: Un Caso de Estudio

espanolEl presente articulo presenta el diseno y aplicacion de una metodologia que integra y aprovecha las ventajas de tres enfoques, usualmente aplicados en forma independiente, para mejorar la calidad de los productos reduciendo su variabilidad funcional. Los enfoques son, la funcion de perdida de la calidad (QLF), el control estadistico multivariante de procesos (MSPC) y el control ingenieril de procesos (EPC). La mejora de la calidad de los productos se puede lograr mediante la deteccion e intervencion de las causas comunes y asignables de variacion que afectan el proceso. La metodologia usada permite integrar perspectivas cualitativas y cuantitativas en la seleccion de las caracteristicas criticas de calidad del producto. Se exponen los resultados de su aplicacion en una empresa piloto del sector de alimentos, en la cual se logro una reduccion del 52.49% en la variabilidad. EnglishThe present paper presents the design and application of a methodology that integrates three approaches, usually applied in an independent way, to enhance the quality of products by reducing their functional variability. The three methods are Quality Loss Function (QLF), Multivariate Statistical Process Control (MSPC) and Engineering Process Control (EPC). Improving product quality is achieved by the detection and control of the common and assignable causes of variation affecting the process. The methodology also allows integrating qualitative and quantitative perspectives for the selection of the critical-to-quality characteristics. By applying the methodology in a food company, a variability reduction of 52.49% was achieved.

Compuestos de Poliéster Reforzados con Fibra de Plátano/Banano (Musa paradisiaca) Modificada Químicamente. Comparación con Fibra de Vidrio y Fique (Furcraea andina)

Samples of composites were prepared using the hand lay-up technique with banana seudo-stem fibers (BSF), fique and glass, in a polyester matrix. The BSF was woven and analyzed untreated and chemically treated with acetic anhydride, epichlorohydrin, and their mixtures. The aim of this work was to characterize and compare the composites obtained using tensile tests, impact test, water absorption capacity and micrographs. The average value of tensile strength for the composite with treated BSF increased respect to untreated BSF and fique. Also, according to the water absorption tests, they showed the smallest weight increase. This finding was attributed to the higher hydrophobicity of the treated BSF. This in turn improved the adhesion with the matrix, as it was corroborated by the micrographs that showed lower displacement on the tensile fracture surfaces.