¨Determinación de un modelo, para pronosticar la demanda de materias primas basadas en métodos cuantitativos, en una empresa textil ubicada en Quito ¨

Se analizó el caso puntual de la empresa Nilotex Scc. y la industria a la que pertenece, esto se realizó con el fin de contextualizar la realidad interna y externa en la cual se desarrolló la organización comprendiendo el año 2015 y 2016, la relevancia de la industria para el país, su influencia en la economía y la historia de los orígenes y evolución de la misma en el contexto global y nacional. El análisis concluyo con las fortalezas, oportunidades amenazas y debilidades de Nilotex Scc. El apropiado análisis de las materias primas brindará a la organización las directrices necesarias para enfocar sus productos importantes, es por ello que el estudio se realizó en el hilo poliéster, principal insumo de la empresa, se buscará un mecanismo sencillo y sin costo para que Nilotex Scc puede obtener un beneficio en el corto plazo y garantizar un saludable manejo de sus inventarios. La empresa entregó datos históricos de consumo, mediante ellos se generaron pronósticos, se estimaron el error mediante el método de mínimos cuadrados, y se opta por la regresión lineal como herramienta base para la generación de pronósticos y se los complementa con una tabla de calculo que permite pronosticar el stock mínimo más adecuado generando reducción de costos y gastos para la empresa. Actualmente se está utilizando en Nilotex SCC

Selection of a Sustainable Structural Beam Material for Rural Housing in Latin América by Multicriteria Decision Methods Means

Latin America presents the need of more accessible housing in the rural areas of the region; however, problems that this populations have to face are cost, accessibility and seismic events that leave structural damages in the buildings of the population, raising the need of resisting permanent housing or temporary shelter. Moreover, the conventional steel materials are not always affordable, which makes us consider the utilization of alternative sustainable materials that are easier to reach and with a seismic resistance. In this sense, the conditions of an earthquake are simulated, specialized software selects and recreates candidate materials and multicriteria decision methods make the final selection of the best material to be evaluated in a simulation. In this way, it has been found that a beam must resist an effort of 5.96 MPa, candidate materials are composites and naturals, and considering mechanical, environmental and price aspects, the decision methods chose the bamboo as the best material. Lastly, another simulation validates the selection, allowing us to conclude that the multicriteria decision methods used succeeded to find the best alternative

Characterization of Unripe and Mature Avocado Seed Oil in Different Proportions as Phase Change Materials and Simulation of Their Cooling Storage

Environmental problems have been associated with energy consumption and waste management. A solution is the development of renewable materials such as organic phase change materials. Characterization of new materials allows knowing their applications and simulations provide an idea of how they can developed. Consequently, this research is focused on the thermal and chemical characterization of five different avocado seed oils depending on the maturity stage of the seed: 100% unripe, 25% mature-75% unripe, 50% mature-50% unripe, 75% mature-25% unripe, and 100% mature. The characterization was performed by differential scanning calorimetry, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The best oil for natural environments corresponded to 100% matured seed with an enthalpy of fusion of 52.93 J·g−1, and a degradation temperature between 241–545 °C. In addition, the FTIR analysis shows that unripe seed oil seems to contain more lipids than a mature one. Furthermore, a simulation with an isothermal box was conducted with the characterized oil with an initial temperature of −14 °C for the isothermal box, −27 °C for the PCM box, and an ambient temperature of 25 °C. The results show that without the PCM the temperature can reach −8 °C and with it is −12 °C after 7 h, proving its application as a cold thermal energy system

Fibra de mocora como refuerzo de resina poliester para aplicaciones mecánicas

INTRODUCTION. The reinforcement of resins with natural fibers is used worldwide and due to the biodiversity of Ecuador it’s natural origin fibers would suppose a contribution to the manufacture of parts as composite materials. OBJECTIVE. Characterize the mocora fiber as reinforcement of unsaturated polyester resin, determine the properties of the material and find the viability of applications in the mechanical area. METHOD. This research begins with the collection and documentation of fiber information. Characterization of the fiber taking measurements, performing microscopy, SEM, analysis of moisture absorption, observation of the reaction of the fiber with the resin, mechanical characterization of the composite material, designing molds for test pieces and mechanical tests based on ASTM standards. RESULTS. It is shown that the fiber has different lengths in 90º orientations with a coating, the fiber has impermeable layers and internal grooves, has an average moisture absorption of 61%, the wood mold resists the pressure, there is encapsulation of the fiber, but It hasn’t wettability with polyester resin. DISCUSSION AND CONCLUSIONS. The mold obtains samples without spills, but the fiber is unfeasible as a composite material under natural conditions, suggesting future investigations with enzymatic treatments to the fiber.INTRODUCCIÓN. El refuerzo de resinas con fibras naturales es utilizado a nivel mundial y debido a la biodiversidad del Ecuador sus fibras de origen natural supondrían un aporte a la manufactura de partes como materiales compuestos. OBJETIVO. Caracterizar la fibra de mocora como refuerzo de resina poliéster insaturada, determinar las propiedades del material y encontrar la viabilidad de aplicaciones en el área mecánica. MÉTODO. Esta investigación comienza con el levantamiento y documentación de información de la fibra. Caracterización de la fibra tomando medidas, realizando microscopia, SEM, análisis de absorción de humedad, observación de la reacción de la fibra ante la resina, caracterización mecánica del material compuesto, diseñando moldes para probetas y pruebas mecánicas en base a normas ASTM. RESULTADOS. Se demuestra que la fibra tiene distintas longitudes en orientaciones 90º con un recubrimiento, la fibra tiene capas impermeables y surcos internos, tiene una absorción de humedad promedio de 61%, el molde de madera resiste la presión, hay encapsulación de la fibra, pero no tiene mojabilidad con la resina poliéster DISCUSIÓN Y CONCLUSIONES. El molde obtiene probetas sin derramamientos, pero la fibra es inviable como material compuesto bajo las condiciones naturales, sugiriendo futuras investigaciones con tratamientos enzimáticos a la fibra

Multicriteria Decision Analysis of Suitable Location for Wind and Photovoltaic Power Plants on the Galápagos Islands

The Galapagos Islands have been declared a World Heritage site due to their unique biodiversity, which makes them a living museum and a natural laboratory for humankind. However, to fulfill the energy needs of its habitants and foreign visitors, the islands have depended on fossil fuel energies that have produced levels of lead and chemical agents that are affecting the islands’ air quality, flora, and fauna. Therefore, zero-carbon initiatives have been created to protect the islands, wherein solar and wind power plants have been studied as reliable alternatives. In this way, Geographical Information Systems based on Multicriteria Decision Methods constitute a methodology that minimizes the destruction and disturbance of nature in order to assess the best location for the implementation of these alternative energy sources. Therefore, by exploring the geographical information along with the Analytical Hierarchical Processes and the Ordered Weighted Average methods, it was possible to identify the potential for solar power plants of 10 MW on each island; likewise, for wind power plants, it was found that the islands possess implementation potential that has been analyzed in the field, showing that the best location is on Baltra Island, but is not limited to it

Selection of a PCM for a Vehicle’s Rooftop by Multicriteria Decision Methods and Simulation

The automotive industry is one of the most contaminant; for this reason, solutions in efficient matter has been proposed over the years. This research contributes to this subject by evaluating the thermal comfort in the internal air of a vehicle by using a 20 mm layer of a phase-change material attached to the rooftop interior of a car. The phase-change material selection is based on a list of other materials proposed in previous research and chosen by multicriteria decision methods. In this sense, the material savENRG PCM-HS22P proved to be the best. Moreover, a simulation using the finite elements method showed how the PCM reduced the temperature of the air by 9 °C when heating and by 4 °C when the temperature drops. To conclude, the multicriteria selection methods chose the best material to absorb energy during the charging process and released it during the discharging event in this automotive application