Revista EIA

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Acceso abierto
Indicadores de alerta temprana de vulnerabilidad macroeconómica
(Revista EIA - Fondo Editorial, 2008) Giraldo, Jorge Alberto
Las crisis financieras generan efectos macroeconómicos nocivos que terminan por afectar el nivel de vida de la mayoría de la población. La identificación, prevención o minimización de sus efectos es tarea de las autoridades económicas, que utilizan distintas herramientas de diagnóstico. En este artículo se explica la metodología de Goldstein, Kaminsky y Reinhart para construir un sistema de indicadores de alerta temprana de crisis financieras, que introduce conceptos innovadores para la realización del análisis y, además, está diseñada para ser aplicada en los países considerados mercados emergentes.
Acceso abierto
Lecciones del concurso de puentes EIA
(2013-10-21) Duque-Uribe, M. P. (Maria del Pilar)
The history, evolution and experience of the bridge contest carried out every year by the Antioquia School of Engineering (EIA) is exposed. The basic structural systems used for bridges are described, the weak points of every system are brought out and some of the contest models are analyzed, according to their structural system, in the way they fault. At last, winner bridges of the four versions of the event are described, and a study of how, through experience, the contestants and organizers had attained and raised the level of contest is exposed.
Acceso abierto
Tecnologías de tratamiento para la tierra Fuller contaminada con aceite dieléctrico
(2013-10-22) Berrío-Giraldo, L. I. (Linda Ivette); Agudelo, E. A. (Édison Alexánder); Cardona-Gallo, S. A. (Santiago Alonso)
In recent years, Colombia has been implementing agreements and regulations for the proper handling and final disposal of hazardous waste, because the amount generated each time is increasing and the adverse impact that these residues in human health and environment. The Fuller earth is an inorganic adsorbent material (mainly aluminosilicate mineral) used in the electrical industry for the regeneration of dielectric oil, a derivative of petroleum used as an electrical and thermal insulation in power transformers. After oil regeneration process, the content of polyaromatic hydrocarbons (or PAH’s by its initials in english) that has Fuller earth it become a hazardous waste that requires proper treatment to reduce its pollution and allows its reuse or safely dispose in a landfill.
Acceso abierto
Remoción de níquel y DQO presentes en las aguas residuales de la industria automotriz mediante electrocoagulación
(2013-10-22) Gonzalez-Silva, G. (German); Valencia, S. H. (Sergio Humberto)
By means of this study was determined if the electrocoagulation technique helps to minimize the nickel and organic matter, chemical oxygen demand (COD) concentration, present in wastewaters from automotive industry. A randomized multilevel factorial experimental design was used; being the current density and reaction time evaluated in three levels, while the separation between electrodes was analyzed at two levels. Electrocoagulation was carried out in a batch reactor using iron electrodes with monopolar arrangement. The acid digestion, atomic absorption air-acetylene flame and the closed reflux-colorimetric (micro COD) analytical techniques were used to determine the content of the contaminants. The conditions where it got the most decontamination of the water analyzed were found; being the Applied current density: 1,04 A/dm2, operative time: 17 minutes y; did not the electrode separation influence. The results show that electrocoagulation could be effective to reduce nickel and organic matter (COD) present in wastewaters from automotive industry.
Acceso abierto
Implementación de un sistema de medición de temperatura empleando fibra óptica para el estudio térmico de transformadores de distribución inmersos en aceite mineral y vegetal
(2013-10-22) Navas, D. F. (Diego Fernando); Cadavid-Ramírez, Héctor; Echeverry-Ibarra, Diego Fernando
Transformers are elements of the utmost importance in the layout of power grids. Their usable lifespan depends on various factors, amongst them, the temperature within their own interior, specially the localized temperature on their insulating material components. Such temperatures are usually approximated through proposed guideline models, however, as stated, these values are approximations and realtime direct measurements would be much more desirable. Due to purely economic reasons, direct measurement is often used for power transformers. However, in the advent of “Smart Grids” distribution system instrumentation will be necessary, as well as the use of cleaner technologies. For research purposes, in this paper, the authors will discuss their experiences in instrumentation with optical fibers in four different distribution transformers submerged in mineral and vegetable oil, for thermal evaluation. The transformers have capacities that range from 15 kVA to 37,5 kVA and operate at voltages of 7620 V / 240 V. This paper also explains the process of identifying which are the optimal temperature measurement points in the interior of the transformer and leads into the results of temperature rise tests with simulated loads through the use of short circuits and through constant reference fault and actual load at two levels to compare measurements within each of the transformers.
Acceso abierto
Impacto del material reciclado en los inventarios de materias primas de una empresa manufacturera
(2013-10-23) Salinas-López, G. A. (Guillermo Antonio); Victoria-Moreno, A. (Anthony); Osorio, J.C. (Juan Carlos)
In this paper, a system dynamics model is designed. This model, together with some management indicators is used to measure the impact of recycled material in an industry. This, in order to provide best elements in decision making process related to the management of raw materials stocks. For this purpose, a review of the main elements that influence the production plan of a business case study is performed. Thus, a characterization of the industry and subsequent configuration of the structure and relationships of the system is obtained, in order to model and simulate using the software Vensim DSS. From these simulations, a review and analysis of the system behavior, as well as variations proposed, in different scenarios and changes in relevant parameters, is executed. At the end, a model that illustrates the behavior of inventory levels of different types of materials as well as the values of some logistics and energy indicators is obtained, revealing the important work ahead in recycling on the region of Valle del Cauca, Colombia.
Acceso abierto
Determinación del color del exocarpio como indicador de desarrollo fisiológico y madurez en la guayaba pera (psidium guajava cv. guayaba pera), utilizando técnicas de procesamiento digital de imágenes
(2013-10-23) Castro-Camacho, J. K. (Jennifer Katiusca); Cerquera-Peña, N. E. (Néstor Enrique); Gutiérrez-Guzmán, Nelson
The colorimetric coordinates analysis of digital images in samples pear guava fruits (Psidium guajava cv. Pear guava) was performed for three times of harvest: traditional harvesting at 120 days after flowering (T1), early harvesting at 112 days after flowering (T2) and, early harvesting at 110 days after flowering (T3), the three group of samples were stored at environmental conditions at a temperature of 26 ºC and 58% of relative humidity and under refrigeration at 7.5 ºC and 85% relative humidity. For color determination two color spaces were used: RGB and CIE-L*a*b*, each of these spaces describes the color of the skin using three components that allow the comparison of its evolution during each step of postharvest. The results showed a typical evolution from deep green, freshly harvested, to light green yellowish colors. The found coordinates allow the reproduction of the colors of the evolution of ripening in printing devices configured in RGB coordinates. From the physicochemical parameters assessed, the respiration rate of the fruit is the most correlated with the change of color during the post-harvest stage.
Acceso abierto
Desarrollo e implementación de un modelo de teoría de restricciones para sincronizar las operaciones en la cadena de suministro
(2013-10-23) Marín-Marín, W. (William); Gutiérrez-Gutierrez, E. V. (Elena Valentina)
This paper presents a methodological and practical proposal to synchronize the logistic operations and decisions in a Colombian ceramic tile supply chain. For doing so, we used two tools from the Theory of Constraints methodology (TOC): the first one refers to the operations synchronization along the supply chain through the so-called method Drum-Buffer-Rope; the second one refers to the development of an accounting tool that allows improving the decision making for each member of the supply chain (Throughput Accounting). The results of the implementation show that an integral analysis of the supply chain could improve the global performance metrics such as service level, production plans fulfillment, inventory costs of raw materials and finished goods, and the company productivity.
Acceso abierto
Why animals come together, with the special case of mixed-species bird flocks
(2013-10-23) Colorado, Gabriel Jaime
El comportamiento de agrupamiento es un fenómeno biológico global y ubicuo en el reino animal que ha atraído considerable atención en muchos contextos. Los dos factores principales que se cree favorecen la vida en grupo son la disponibilidad de alimento y la presencia de predadores. En esta revisión se exploraron las principales teorías publicadas en la literatura que tratan de dar explicación al comportamiento de agrupamiento en animales. Esta revisión se divide en dos secciones. Inicialmente, se describen las principales teorías así como los potenciales mecanismos asociados al beneficio de agruparse. Posteriormente, se presenta un caso especial en un sistema social animal llamado bandadas mixtas de especies de aves, explorando la información disponible en relación a las causas potenciales que hacen que las aves se asocien en esta particular agregación.
Acceso abierto
Evaluación ambiental para procesos que usan residuos de la industria de los biocombustibles como materias primas
(2013-10-24) Valencia-Botero, M. J. (Mónica Julieth); Cardona, Carlos Ariel
The industry of biofuels generates a lot of amounts of residues, which could be used to produce added-value products. In this work, a Life Cycle Assessment (LCA) methodological approach was used in the cases of glycerol and sugarcane bagasse during their productions and their uses as raw materials in four different processes. The aim of this work was to determine the environmental impact of those processes, by calculating the Greenhouse Gases (GHG) associated to their lifecycles. The results indicated that the GHG emissions from glycerol processes were larger than processes involving sugarcane bagasse. Nevertheless, the processes using glycerol as raw material could be considered as more efficient, since the GHG emissions associated with the glycerol use per mass unit were 75% lower than GHG emissions when the glycerol is used, with regard to sugarcane bagasse.
Acceso abierto
Laboratory evaluation of compactability and performance of warm mix asphalt
(2013-10-25) Álvarez, Allex E.; Aaron-Pimienta, A. L. (Aixa Leonor); Kirby-Estakhri, C. (Cindy)
Mezclas asfálticas tibias (MAT) es el término empleado para describir el conjunto de tecnologías que permiten la fabricación de mezclas asfálticas a menores temperaturas que las especificadas para mezclas asfálticas en caliente (MAC) convencionales. Esta reducción de temperatura conlleva ventajas, comparadas con la construcción de MAC, que incluyen ahorros de energía, menores emisiones y condiciones de trabajo más seguras. Sin embargo, las MAT son tecnología relativamente nueva y aún están en evaluación diferentes aspectos. Este artículo evalúa algunos de estos aspectos incluyendo compactabilidad y su relación con el diseño de mezcla y desempeño de MAT en laboratorio (i.e., deformación permanente y resistencia a la fisuración), fabricadas con tres modificadores tipo MAT, específicamente Advera®, Sasobit® y Evotherm®. Los resultados correspondientes mostraron que la compactabilidad en laboratorio para las MAT es equivalente o mejor que la obtenida para la MAC empleada como referencia (o mezcla de control), conllevando a menores contenidos óptimos de asfalto seleccionados con base en una densidad de diseño específica (i.e., 96%). En términos de desempeño, la inclusión de los aditivos tipo MAT generó la reducción de la resistencia de la mezcla ante deformación permanente, aunque su resistencia al agrietamiento podría permanecer igual o incluso mejorar en comparación con aquella de la MAC.
Acceso abierto
Síntesis y caracterización de óxidos mixtos de sílice-titania preparados por método sol-gel y tratamiento hidrotérmico
(2013-10-25) Pabón, Elizabeth; Borja-Ordóñez, S. M. (Sandra Milena); Ordóñez-Loza, J. (Javier); Ramírez-Vélez, A. (Alejandro)
Mixed oxides SiO2-TiO2 were prepared of different compositions by the sol-gel method combined with hydro-thermal treatment (HT), using tetraethylorthosilicate and titanium tetraisopropoxide as precursors of the sources silica and titanium, respectively. Hybrids obtained using the nonionic surfactant Triton X100, were carried out with TH for 48 hours at 120 °C, washed, dried at 70 °C/24 h, and calcined at 550 °C/2 h (heating rate 1 °C/min.). The mixed oxides were characterized by nitrogen physisorption, SEM, TEM, FTIR, XRD and TGA. The results indicate that the materials presented high specific surface area in the range of 190-805 m2/g, average pore diameter 4,0- 6,5 nm, additionally, the silica-titania mixed oxides exhibits anatase phase desirable in photocatalytic reactions.
Acceso abierto
Influencia de los recubrimientos dúplex sobre las propiedades mecánicas y resistencia al desgaste del acero AISI 4140 bonificado
(2013-10-28) Bolívar-Osorio, F. J. (Francisco Javier); Bejarano-Gaitán, G. (Gilberto); Gómez-Botero, M. A. (Maryory Astrid)
The AISI 4140 steel is a low chrome/molybdenum alloyed steel with high tensile strength and good toughness, which is normally used for the manufacture of machine parts such as gears, crank shafts, camshafts, etc. However, its wear resistance is quite limited and this is usually improved by nitriding surface treatment. The purpose of this study was to increase the mechanical properties and wear resistance of 4140 steel by applying a DUPLEX surface treatment consisting of a liquid nitriding (known as Teniffer) followed by the deposition of a titanium nitride (TiN) hard coating. The crystalline microstructure was evaluated by Xray diffraction (XRD), morphology and elemental chemical composition was determined by microscopy SEM and energy dispersive X-ray spectroscopy (EDS), tribological properties were tested using a tribometer type ballondisc and micro hardness was determined by the Vickers method.
Acceso abierto
Influencia de la relación masa/área en las propiedades de cerámicas de PZN-5PT-5BT
(2013-10-28) Villaquiran, C. F. (Claudia Fernanda)
0,90Pb(Zn1/3Nb2/3)O3–0,05PbTiO3-0,05BaTiO3 (PZN-5PT-5BT) ceramic powders, with majority perovskite phase, were synthesized using the columbite method. These powders were shaped into cylindrical pellets, which had two different mass/area ratios. The pellets were sintered within 1040 and 1150°C during one hour and under a rich lead oxide atmosphere. The percentage of perovskite phase, for both powders and ceramics (surface and interior), was obtained by X-rays diffraction spectrum, where it was observed that ceramic samples present higher percentage of perovskite phase and the highest density value when sintered at 1100 ºC during one hour. Morphology was analyzed using scanning electron microscopy. It revealed that the mass/area ratio influences the stabilization of the perovskite phase within the sintering process, the bigger the content of mass for area unit the more stable the perovskita phase
Acceso abierto
Control de fasciola hepatica en el agua de consumo animal a través de filtración rápida y lenta
(2013-10-28) González-Morales, C. (Carolina); Sánchez, G. A. (Gladys Adriana); Castro-Jiménez, C. C. (Camilo César); Gómez-Carmona, C. (Catalina)
The bovine fasciolosis is a zoonosis caused by Fasciola hepatica transmitted by consuming water and / or vegetables contaminated with the digenea. This disease causes significant economic losses in the dairy producer regions of Antioquia. In order to remove the eggs of the parasite from water, we designed and built two filters (rapid and slow filtration), using industrial sand as filter bed (effective size 0.45-0.55 mm). A rapid filtration system was evaluated at speeds of 5 and 8 m/h for a sand bed height of 60 cm and a slow filtration system at a speed of 1.46 m/h for sand bed heights of 30 and 40 cm. The variation of effluent flow and removal efficiency of both turbidity and parasite eggs were determined during the run of each filtration. The results show that all filters operating under the described features are 100% efficient in removing the F. hepatica eggs from the water. The turbidity removal percentages were 85.5% and 79.4% for filters operating at speeds of 5 m/h and 8 m/h respectively.
Acceso abierto
Metodología basada en los algoritmos Vega y Moga para solucionar un problema multiobjetivo en un sistema de producción job shop
(2013-10-29) Coca-Ortegón, G. A. (Germán Augusto); Castrillón, Omar Danilo; Ruiz-Herrera, S. (Santiago)
This paper presents a methodology that aims to minimize simultaneously, in a “Jo b Shop” production system the following variables: process time (makespan time), cost of direct labor and also the fraction defective generated by operator fatigue. For this purpose, are taken and fused elements of genetic algorithms Vega and Moga, through the following steps: generating the initial population, form the new population, obtaining the appropriate analysis of variance and finally compared with a hybrid method of weighted sums and genetic algorithms. According to the above, when evaluating the solution faster processing time corresponding to the method based on algorithms Vega and Moga, respect to the solution faster processing time calculated from the method based on weighted sums and genetic algorithms, states that the first one exceeds the second performance as: for process time variable (in hours) at 27.86%, for variable in process time (in weeks) at 1.25%, in terms of the variable cost of direct labor in 6.73% and, as to the variable defective fraction in 25.85%.
Acceso abierto
Modelo de laboratorio de prospectiva en gerencia para la Escuela de Ingeniería de Antioquia —EIA—
(2013-10-29) Botero-Tobón, R. D. (Rubén Darío); Calle-Zapata, V. (Vladimir); Echavarría-Goicochea, M. V. (María Victoria); Galindo-Monsalve, R. (Rafael); Osuna-Ramírez, S. A. (Sergio Andrés)
This paper presents a proposal of a model for the creation of a center of foresight in management at EIA. This proposition is based on the identification of the needs of organizations to understand the future, as a result of globalization and the changing environment. Initially a short analysis is made of the theoretical framework of the prospective as well as a summary of the results of interviews with managers of some institutions about the need to forecast the future as key to sustainable business success. Finally, a model is proposed for the creation of the Centre of foresight to be implemented at EIA as a center of studies of the future of management in terms of the development of the society, and more specifically of the enterprises in order to achieve greater accuracy of the facts to envision the possible future scenarios and to reduce the uncertainty level to make better decisions in the present. The proposed model includes the strategic and operational frameworks.
Acceso abierto
Efecto del contenido de carbono sobre la resistencia al desgaste abrasivo de recubrimientos de CrC depositados por pulverización catódica magnetrón
(2013-11-05) Gómez-Botero, M. A. (Maryory Astrid); Lousa, A. (Arturo); Esteve, J. (Joan)
Chromium carbide coatings on steel are a good candidate for applications on forming and molding dies. The high mechanical strength, chemical resistance and high temperature stability of Cr3C2 phase can be compatible with the severe abrasive wear and corrosion found in those manufacture operations. In this work chromium carbide coatings deposited by means of RF magnetron sputtering showed carbon contents between 25 % and 58 % by EDS analysis. Hardness values of these coatings were between 15 and 24 GPa, being the hardest values in the samples with carbon content in the 39-53 % range. The abrasive wear behavior of the coatings was evaluated by using a dimple grinder with diamond powder. The volume of the abrasion craters was measured from the images obtained with the interferometric microscope, and further corroborated by geometrical volume calculation based in profilometer sections that were measured. Abrasive wear behavior showed a marked dependence with carbon content. The lowest abrasive wear was obtained for the coatings with the highest carbon content.
Acceso abierto
Resistencia al desgaste erosivo-corrosivo de aceros austeníticos fermanal
(2013-11-05) Aperador, W. (William); Bautista, J. H. (Jorge Hernando); Betancur, J. D. (Juan David)
We obtained austenitic alloys of the Fe-Mn-Al, Fe in the range (4.9~11.0 wt% Al) - (17.49~34.3 wt% Mn) -(0, 43 ~ 1.25 wt% C), which were melted in an induction furnace from high purity materials. The alloys were evaluated with respect to corrosion, wet erosion and corrosion-erosion at an impact angle of 90°. For the evaluation of corrosion a solution composed of 0.5 M NaCl and silica particles with size between 210 to 300 microns was used in order to analyze the effect of aluminum and manganese content in the resistance to erosion and corrosion-erosion of these alloys. To characterize the corrosion, response technique was used by potentiodynamic polarization curves and using the same technique as Tafel extrapolation, the microstructural characterization by scanning electron microscopy (SEM), and the composition of corrosion products were analyzed using diffraction of X-rays (XRD).
Acceso abierto
Dielectric properties of poly(vinyl alcohol) hydrogels prepared by freezing/thawing technique
(2013-11-06) Londoño, M. E. (Martha Elena); Jaramillo, Juan Manuel; Sabater I Serra, Roser; Vélez, Juan Manuel
Por medio de espectroscopia dieléctrica (DRS) y calorimetría diferencial de barrido (DSC) se investigaron las propiedades dieléctricas de los hidrogeles de alcohol polivinílico –PVA– entrecruzados por ciclos repetidos de la técnica congelamiento/descongelamiento. La asociación de los grupos polares del polímero disuelto seguida de su cristalización produce la reticulación del polímero. La espectroscopia dieléctrica obtenida entre -50 °C y -10 °C demostró la existencia de un proceso de relajación secundario asociado con la movilidad de grupos laterales polares OH de la cadena principal, la relajación b. Los ciclos de congelamiento/descongelamiento afectan fuertemente este proceso. El fenómeno dieléctrico predomina en todas las muestras como lo evidencia el valor menor de 1 de tan d. Además, se analizó el efecto del entrecruzamiento en la dinámica de la relajación secundaria.