Revista EIA

URI permanente para esta colección

https://repository.eia.edu.co/handle/11190/52

Noticias

Navegar

Mostrando 1 - 20 de 212

Acceso abierto
A numerical approach for fault detection in beam-like structures using modal strain energy
(2013-12-16) Riveros, Carlos Alberto; García, E. F. (Edwin Fabián); Builes, M. A. (Manuel Alonso)
La detección de daño estructural usando vibraciones se fundamenta en el hecho de que pueden usarse mediciones de cambios en las propiedades de vibración de una estructura para determinar la ocurrencia de daño estructural, por lo tanto, existe una fuerte necesidad de desarrollar e implementar métodos de detección de daño y óptima localización de sensores que tengan en cuenta el uso de instrumentación limitada y su efecto en la predicción de deterioro estructural. En este artículo se presentan los resultados de la implementación numérica de un método de óptima localización de sensores previamente desarrollado. Se ensambla un modelo en elementos finitos con base en un modelo de un puente ferroviario de tipo viga-cajón. Luego, el método de índice de daño se emplea para la identificación de daño estructural, con base en las mediciones obtenidas de los sensores. Los métodos de óptima localización de sensores y de detección de daño presentados en este artículo se basan en el uso de la energía modal de deformación. Los resultados numéricos muestran que la energía modal de deformación es apropiada para aplicaciones de seguimiento continuo de daño en estructuras y que puede usarse como una herramienta útil para inspecciones de integridad estructural en estructuras tipo viga.
Acceso abierto
A systematic review on identification of excitation systems for synchronous generators
(2013-12-16) Saavedra-Montes, A. J. (Andrés Julián); Ramos-Paja, C. A. (Carlos Andrés); Ramírez, J. M. (José Miguel)
Este artículo presenta el estado del tema en identificación de sistemas aplicada a sistemas de excitación. Primero se presenta una visión general de identificación de sistemas y de los sistemas de excitación de generadores sincrónicos, resaltando las características impuestas por los sistemas de excitación en un proceso de identificación. Luego se presenta el diseño de un método de clasificación basado en las características de los sistemas de excitación. El resultado del método es una matriz que condensa los asuntos discutidos en más de 40 publicaciones. El estado se establece desde el análisis de los resultados y adicionalmente se reconocen áreas abiertas de investigación en la identificación de sistemas de excitación.
Acceso abierto
Ajuste de curvas mediante métodos no paramétricos para estudiar el comportamiento de contaminación del aire por material particulado PM10
(2013-12-16) Reina, J. (Jhovana); Olaya, J. (Javier)
One of the main air pollutants is the particulate matter whose aerodynamic diameter is less than 10 micrometers, usually referred as PM10. It is a fact that the PM10 behavior in the air varies in an irregular way, and also in a temporal way in the atmosphere, mainly due to human activities, to unstable atmospheric conditions, and to meteorological phenomena. Our main purpose is to characterize through a nonparametric smooth model the PM10 daily behavior, taking into account the day of the week, and the precipitation levels. We illustrate the model using records on PM10 contamination, as well as on data on rain precipitation in the north side of Cali, Colombia. We estimate daily typical curves of the PM10 behavior using kernel and spline estimators. We processed these data using the free distribution statistical software R. The estimated curves allow us to observe a PM10 unimodal behavior during the morning hours, which varies from one day to another and from rainy to non-rainy days. The fitted models allow a robust characterization of the PM10 daily behavior, considering heteroscedastic observations on a multiple response per design point scenario.
Acceso abierto
Alcohol carburante: actualidad tecnológica
(2014-05-06) Ocampo, Aquiles
This study shows technical, economical, and environmental aspects which have to be handled in the design of the new plants to be built in Colombia in order to produce the alcohol required to fit the new rules established by the national government. It is seen that in the next few years, the safer way of obtaining it is from sugar cane, but on the other hand, we can see the uprising of new alternatives which could compete with it latter. Up to now, the cost of producing dry ethanol is higher than obtaining gasoline. Finally, environmental problems which have to be handled in ethanol production plants are described.
Acceso abierto
Algoritmo de integración para materiales no lineales considerando los efectos de viscoplasticidad, endurecimiento cinemático no lineal y daño
(2014-05-07) Gómez-Cataño, J. D. (Juan David)
In the Finite Element Method (FEM) material non-linearities are considered through incremental formulations in terms of a pseudo-time variable for the case of rate independent models and a real time variable in the case of rate-dependent models. The incremental statement of the problem implies that the constitutive models need to be time-integrated at the local level. In this article we discuss a standard algorithm available in the literature where additionally we have incorporated the effects of non-linear kinematic hardening, viscoplasticity, and damage. The algorithm is incorporated into a FEM code. In order to verify the correctness of our implementation we have particularized the model to the case of a creep law available from literature for solder alloys. Numerical simulation results are compared with experiments taken from the literature.
Acceso abierto
Algoritmo etapa a etapa para la simulación de cascadas de extracción en fase líquida aplicando el modelo de equilibrio
(2013-12-17) Sánchez-Correa, César Augusto; Arturo, Jaime E.; Cárdenas, Andrés C.
It is shown a stage-by-stage solution method for the group of mass balances, equilibrium relationships, sum of compositions and enthalpy equations (MESH equations) that represents the equilibrium model for a countercurrent multistage liquid-liquid extraction arrangement. The theoretical foundation is in thermodynamics: liquid-liquid equilibrium, isothermal flash, and adiabatic flash. The algorithm exceeds the scope of graphics and isothermal methods used in the study of extraction processes, which is applicable to very common typical situations: heat transfer by stage, adiabatic stages, and different temperatures in feed and solvent streams. The algorithm is illustrated in three examples, the first two in isothermal operation with three components (water, acetic acid and butyl acetate) and ten stages, and a third one more elaborated involving heat transfer with four components (water, acetic acid, butanol, butyl acetate) and fifteen stages.
Acceso abierto
Un algoritmo genético híbrido y un enfriamiento simulado para solucionar el problema de programación de pedidos Job Shop
(2013-12-17) Meisel-Donoso, José David; Prado, L. K. (Liliana Katherine)
Job Shop Scheduling Problem (JSP), classified as NP-Hard, has been a challenge for the scientific community because achieving an optimal solution to this problem is complicated as it grows in number of machines and jobs. Numerous techniques, including metaheuristics, have been used for its solution; however, the efficiency of the techniques, in terms of computational time, has not been very satisfactory. Because of this and for contributing to the solution of this problem, a simulated annealing (SA) and an improved genetic algorithm (IGA) have been proposed. The latter, by implementing a strategy of simulated annealing in the mutation phase, allows the algorithm to enhance and diversify the solutions at the same time, in order not to converge prematurely to a local optimum. The results showed that the proposed algorithms yield good results with deviations around the best values found not exceeding 5 % for more complex problems.
Acceso abierto
Algoritmo para la solución numérica de sistemas de ecuaciones no lineales mediante una estrategia de optimización global basada en análisis de intervalos
(2013-12-17) Gómez, L. A. (Luis Antonio); Reyes, E. J. (Edilberto José); Correa, Carlos Rodrigo
In this paper an algorithm for the numerical solution of nonlinear equations systems is presented. For this purpose the system of equations becomes a function of real value which will be minimized, in the global sense, in a given initial domain (a box in n) using analysis of intervals. The designed algorithm has the ability to determine the existence or not of solutions to the system of equations in a given box. The solutions of the system of equations, if they exist inside the given box, are expressed by means of enclosures by sub-boxes whose size is smaller than the established accuracy. There is not restriction about the relationship between the number of equations and the number of unknowns of the system. It is also carried out an analysis of the convergence of the algorithm, and the results of their application are shown for some test problems.
Acceso abierto
Ambiente inteligente distribuido de aprendizaje: integración de ITS y CSCL por medio de agentes pedagógicos
(2014-05-08) Ovalle, D. A. (Demetrio Arturo); Jiménez-Builes, J. A. (Jovani Alberto)
In this article we start describing the theory inside the Distributed Intelligent Learning Environment (DILE), Intelligent Tutorial Systems (ITS), Computer-Supported Collaborative Learning (CSCL), and Multi-Agent Pedagogical Systems (MAS); therefore, we can present the Multi-Agent Teaching/Learning system called ALLEGRO. Besides of putting all the areas mentioned and those regarding the research of Distributed Artificial Intelligence (DAI) together, ALLEGRO fundaments its instructional paradigm in three pedagogical models: conductive, cognitive (distributed cognition and problem-based learning) and the social-historical theory. The validation was made through studying different cases handling digital graphics for graduate courses on Architecture majoring.
Acceso abierto
Análisis de la ingeniería de requisitos orientada por aspectos según la industria del software
(2014-05-09) Londoño, L. F. (Luis Fernando); Anaya-Hernandez, R. (Raquel); Tabares-Betancur, M. S. (Marta Silvia)
Applying good practices to manage software requirements is a basic condition to obtain quality products. Therefore, it is important that software companies maintain a constant research around of new techniques and mechanisms to improve requirements activities such as elicitation, specification, and modeling. In this paper, we present a study of most representative aspect-oriented requirement approaches in order to analyze the way how these could support issues confronted by software companies during early stages of the lifecycle. Thus, we make a comparative analysis among approaches under criteria defined such as scope, traceability, requirements composition, conflict management, mapping, validation-verification, and scalability. Results achieved allowing us to know opportunities offered by aspect-oriented approaches so as to improve the requirement process.
Acceso abierto
Análisis de la trazabilidad desde la perspectiva de la orientación a aspectos
(2014-05-07) Tabares-Betancur, M. S. (Marta Silvia)
In this article an analysis about traceability concerns from the aspect-oriented software development over a software system is presented. To achieve that, the general concepts about traceability and the aspect oriented approaches is treated; also the way of this technique can provide elements to verify reliability and evolution of the requirements in the software development process. To treat traceability from this way will drive to developer to identify general elements necessary to determine trace of crosscutting concern when these affect other concerns, and in turn how different pieces of a software artifact associated to this concern type have evolved and affected others along the development of life cycle.
Acceso abierto
Análisis de sensibilidad espacial de un modelo hidrodinámico del embalse Punchiná (Antioquia)
(2013-12-17) Escobar, C. A. (Carlos Alejandro)
This paper presents a methodology to assess explicitly the optimal value of the numerical parameters in a hydrodynamic model, such as the grid resolution (horizontal and vertical direction) and the calculation time interval. The methodology is based on a cost-benefit analysis which seeks a desirable balance between the quality of the numerical solution and the required computational time. The spatial nature of the sensitivity analysis presented allows us to determine in each calculation grid cell the alteration of the numerical solution due to changes in the numerical or physical parameters in the model. According to this, it was possible to determine within the Punchiná reservoir where and to what extent are relevant the grid resolution, the time interval, the bed roughness, and the eddy viscosity coefficient.
Acceso abierto
Análisis de umbrales empíricos de lluvia para el pronóstico de movimientos en masa en el Valle de Aburrá, Colombia
(2013-12-17) Aristizábal, E. (Edier); Gonzalez, T. (Tommy); Montoya, Juan David; Vélez, Jaime Ignacio; Martínez, H. (Hernán); Guerra, Alexánder
Mass movements are the product of a progressive reduction of strength of slope geomaterials by human actions or natural processes, such as weathering, and triggered by external factors like rainfall or earthquakes. These events have demonstrated throughout history its destructive capacity, causing huge human and economic losses, especially in tropical and mountainous terrains, such as the Aburrá Valley. For this reason new studies on rainfall forecasting, real-time monitoring and the definition of critical rainfall thresholds have become essential tools for the implementation of early warning systems.
Acceso abierto
Análisis del conocimiento en la relación agua-suelo-vegetación para el Departamento de Antioquia
(2014-05-06) Villegas-Palacio, J. C. (Juan Camilo)
This paper presents a compilation of the main results obtained in the Antioquia Department about the interactions between water, soil, and vegetation. Although there is an advanced knowledge in some aspects of this relationship, it is necessary to go deep into other ones which have not been approached in an integral manner. Likewise, it is necessary to enhance the research in order to cover the diversity of ecosystems of the Department.
Acceso abierto
Análisis del funcionamiento de plantas de manejo de residuos sólidos en el norte del Valle del Cauca, Colombia
(2013-12-17) Marmolejo, Luis Fernando; Torres, P. (Patricia); Oviedo, R. (Ricardo); García, M .(Mariela); Díaz, Luis F.
In Colombia, the acceptance of resource recovery is demonstrated through the high number of municipalities which have introduced this alternative in their integrated solid waste management plans, together with the increasing number of solid waste management facilities (SWMFs) that have been established. This situation also highlights the need for a comprehensive evaluation of the existing experiences as well as research and development around this topic. In this paper, the performance of five SWMFs located in municipalities in northern Valle del Cauca is analyzed. The analysis shows that, despite the fact that SWMFs have operational deficiencies, features such as markets for their products, employment generation and avoided costs in waste disposal in landfills show sufficient grounds for their continuity. Key elements to strengthen SWMFs performance are long-term awareness of service users, adaptation of technologies to the context, enhancement of managerial capacity and better support to resource recovery within the national political framework.
Acceso abierto
Análisis del proceso de deshidratación de cacao para la disminución del tiempo de secado
(2013-12-17) Tinoco, Héctor A.; Ospina, D. Y. (Diana Yomali)
Cocoa is one of the products demanded by the international agricultural market; some multinational companies have invested from its beginnings in research and development, in order to obtain new products. Some factors increase the costs in cocoa-based products, which can be attributed to market conditions (supply and demand), cocoa transformation process, agricultural processes and procedures, among others. This study focuses on a process of industrial transformation that is usually a final step in a series of operations to get dried cocoa beans. Certain variables such as time, temperature, and humidity establish the effectiveness of drying of cocoa. This research suggests the possibility of reducing industrial drying time without affecting the organoleptic properties, changing humidity and temperature. For this proposal experimental tests of drying and computational analysis, using the finite element method to study the drying process, were carried out.
Acceso abierto
Annual and diurnal cycles of the inverse relation between plant transpiration and carbon sequestration
(2014-05-09) Moreno-Ramírez, H. A. (Hernán Alonso)
El conocimiento de los ciclos biogeoquímicos y, en especial, de los balances de carbono es clave para la validación de los modelos de cambio global para el presente y el futuro cercano. Como consecuencia, en el mundo se estudian las fuentes y los sumideros de carbono. Uno de esos sumideros es la vegetación del planeta, que involucra los procesos de respiración y fotosíntesis y cuyo comportamiento se empieza a estudiar. Las tasas de captura del carbono están muy ligadas a la transpiración mediante un proceso de difusión molecular en los estomas, que puede registrarse por un sistema micrometeorológico de eddy covarianza. Este artículo explora los ciclos anuales y diurnos de los flujos netos de CO2 y calor latente de seis ecosistemas diferentes. Se desarrollan diversos análisis de escala temporal, basados en la física de la transpiración, y se halla una relación cuasilineal entre los flujos netos de calor latente y CO2, más fuerte en las áreas con mayor cobertura vegetal. La temporada del monzón norteamericano incrementa la captura de carbono y la relación entre la evapotranspiración y el intercambio de gas carbónico se mantiene en las diferentes escalas temporales analizadas (horas, días, meses).
Acceso abierto
Aplicación de los SIG para la evaluación del estado de conservación del hábitat del Paujil De Pico Azul Crax Alberti (Aves: Cracidae) en el Nororiente de Antioquia, Colombia
(2014-05-07) Molina-Giraldo, A. M. (Adriana María); Barros-Martínez, J. F. (Juan Fernando)
The blue-billed curassow, Crax alberti, is a critically endangered endemic bird from the northern part of Colombia, mainly subjected to habitat loss and subsistence hunting. Geographic Information Systems (GIS) were used to compare the conservation status of forested areas, habitat of the blue-billed curassow, in 15 municipalities of the northeastern region of Antioquia for two different time periods (1986 and 2002). The developed application using digital cartography, allowed the classification of eight zones defined for the study area in order to analyze conservation priorities. Recommendations are made as well for future applications of GIS as a management tool for threatened species in Colombia.
Acceso abierto
Aplicación de redes neuronales en la clasificación de arcillas
(2013-11-13) Gómez, Jairo; Sánchez, Jaime; Ocampo, Aquiles; Restrepo, José William; Aplicação de redes neuronais na classificação de arcillas
Clays are the main raw material in the manufacture of products for the construction sector, such as tile, veneer, flooring and bricks. Small and medium enterprises generally use brick clays of different mineralogical origin, classified in order to formulate their mixtures according to the production team experience; the uncertainty associated with this method causes that a portion of their manufactured products are rejected, because their properties do not meet the technical specifications. This paper presents a methodology based on neural networks for classification of clays, based on the clay properties to be used to make the pasta, with the aim of reducing the number of rejected products. It used different network topologies for classification, and chose the one which have been found capable to predict the training and testing samples with an accuracy of 97.79 % and 94.12 %, respectively.
Acceso abierto
Aplicación del modelo de inventario manejado por el vendedor en una empresa del sector alimentario colombiano
(2013-11-18) Arango-Serna, Martín Darío; Zapata Cortés, Julián Andrés; Adarme Jaimes, Wilson
This paper presents the application of VMI (Vendor Managed Inventory) in a Colombian enterprise that distributes food products. Here it is shown a clear definition of VMI and it is analyzed the key elements and the most important VMI models that can be found in related research literature. Also presents a comparative assessment of two methods proposed in the literature for calculating the replenishment quantities in a VMI context, which are compared with the current procedure implemented for such propose in the company.