Dyna
URI permanente para esta colecciónhttps://repositorio.unal.edu.co/handle/unal/259
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Ítem Remote laboratory prototype for automation of industrial processes and communications tests(Universidad Nacional de Colombia Sede Medellín, 2014-06-24) Castrillón-Ospina, Sebastián; Hincapie, Luz Inés; Zapata-Madrigal, GermánThis paper presents the initial phase of the approach and implementation of a prototype of virtual infrastructure for teaching and lab development in the areas of Industrial Automation and Industrial Communications. The proposed prototype allows remote lab practice using: internet, VMware virtualization and management through Netlab. It allows easy and permanent access to the automation software and hardware necessary for an adequate student experience with real devices.Ítem Review papers(Universidad Nacional de Colombia Sede Medellín, 2014-06-24) Ramos Paja, Carlos AndrésÍtem Correct citation in dyna and anti-plagiarism editorial policy(Universidad Nacional de Colombia Sede Medellín, 2014-06-24) Velásquez, Juan D.Ítem The importance of being chemical affinity. part iv: the first flowers(Universidad Nacional de Colombia Sede Medellín, 2014-04-24) Salas-Banuet, Guillermo A.; Ramírez-Vieyra, José; Restrepo-Baena, Oscar; Noguez-Amaya, María; Cockrell, BryanAfter the power void caused by the Roman Empire’s decline, Medieval Europe is involved in a combat climate for the power. The new Christian church from Rome expands and includes kings and emperors. The Christian pope seeks to compel all believers to subscribe the closed religious perspective of that time. However it is religious people who recognize the necessity to observe nature and the world in a different way. The discovery, translation and diffusion of the classic Greek philosophers’ texts allow the initiation of independent thinking, which in turn, spurs the Renaissance and Illustration ages. The inductive thinking method begins with the purpose of finding other ways to interpret nature and advance the thought process. Therefore during the XVI century alchemy is questioned and the first treatises on empirical metallurgy appear, considered to be the foundations of modern science. During the XVII century some individuals begin experimenting with residual alchemical concepts. The first hypotheses on key chemical concepts and phenomena appear which frame the logic and rational thought process during the XVIII century. The concept of affinity emerges as a way to describe the relations among substances, observed during the formation of compounds, and as an analogy to human relations. Published works regarding the components of the thinking process consolidate the basic concepts of chemical bonding and related themes.Ítem The importance of scientific authors' identity in the digital era(Universidad Nacional de Colombia Sede Medellín, 2014-04-20) Velásquez, Juan D.Ítem The la facultad de minas 1970-2012(Universidad Nacional de Colombia Sede Medellín, 2014-04-20) Branch Bedoya, John WillianÍtem Review of the aims and scope of the journal(Universidad Nacional de Colombia Sede Medellín, 2014-02-25) Velásquez Henao, Juan DavidÍtem Changes in the editorial board of the journal(Universidad Nacional de Colombia Sede Medellín, 2014-02-25) Branch Bedoya, John WillianÍtem A first course in software engineering methods and theory(Universidad Nacional de Colombia Sede Medellín, 2014-02-25) Zapata Jaramillo, Carlos Mario; Jacobson, IvarEven though the software engineering curriculum has been designed many times, some problems still remain: the gap between academy and industry, the failure to continuously update the courses, the difficulties for combining theory and practice, and the lack of a sound, widely accepted theoretical basis. The SEMAT (Software Engineering Methods and Theory) initiative has been proposed for addressing some of the aforementioned problems. Based on the main ideas related to SEMAT, in this paper we propose a first course that introduces students to the main issues about SEMAT. This course is planned to be included in the System and Informatics Engineering Program belonging to the Universidad Nacional de Colombia, Medellin Branch. Also, we discuss the way in which this course addresses the previously diagnosed problems.Ítem Enterprise architecture as tool for managing operational complexity in organizations(Universidad Nacional de Colombia Sede Medellín, 2014-06-25) Arango Serna, Martín Darío; Londoño Salazar, Jesús Enrique; Branch Bedoya, John WillianDifferent types of companies and organizations around the world, in spite its size, economic activity, nature, capital managed by them, and many more aspects, are heading towards diverse daily challenges that must be overcomed agilely, in order to compete successfully in a globalized world operating under highly dynamic environments. In this sense, the fact that companies in its internal operation, must be prepared well enough to respond efficiently, agile and innovative to the challenges and needs they face is taking more relevance. This paper states the importance of information technologys and the development of an enterprise architecture model, as an instrument that allows companies to face challenges related to complexity which is represented in the organization's operative environment.Ítem Iron ore sintering part 2. quality indices and productivity(Universidad Nacional de Colombia Sede Medellín, 2014-01-22) Mochón, Javier; Cores, Alejandro; Ruiz Bustinza, Íñigo; Verdeja, Luis Felipe; Robla, Jose Ignacio; Garcia Carcedo, FernandoSinter plants have to process mineral mixes in order to obtain sinter of a suitable composition and quality to be loaded into the blast furnace. For this purpose a series of parameters need to be taken into account, such as the nature and composition of each component of the mineral mix and the conditions of the manufacturing process. Sinter is subjected to in-depth characterisation in terms of chemical and granulometric analysis, determination of the mineral phases in its structure and of quality indices such as reducibility, low temperature degradation, reduction degradation, and tumbler strength. It is also important to operate sinter plants with high productivity and to ensure a uniform sinter composition and quality so as to facilitate the steady state operation of the blast furnace.Ítem A comparison of exponential smoothing and neural networks in time series prediction(Universidad Nacional de Colombia Sede Medellín, 2013) Velásquez Henao, Juan David; Zambrano Pérez, Cristian Olmedo; Franco Cardona, Carlos JaimeIn this article, we compare the accuracy of the forecasts for the exponential smoothing (ES) approach and the radial basis function neural networks (RBFNN) when three nonlinear time series with trend and seasonal cycle are forecasted. In addition, we consider the recommendations of preprocessing by eliminating the trend and seasonal cycle using simple and seasonal differentiation. Finally, we use forecast combining for determining if there is complementary information between the forecasts of the individual models. Our numerical evidence supports the following conclusions: ES models have a better fi t but lower predictive power than the RBFNN; detrending and deseasonality allows the RBFNN to fi t and forecast with more accuracy than the RBFNN trained with the original dataset; there is no evidence of information complementarity in the forecasts such that the methodology of forecasts combination is not able to predict with more accuracy than the RBFNN and ES methodologies.Ítem Impact of electrical energy efficiency programs, case study: food processing companies in cuenca, ecuador(Universidad Nacional de Colombia Sede Medellín, 2014-04-22) Carrillo-Rojas, Galo Jose; Andrade-Rodas, Juan; Barragán-Escandón, Antonio; Astudillo-Alemán, AnaThis exploratory study illustrates the effects of the application of electrical energy efficiency programs in 7 food processing companies in Cuenca, Ecuador. The research encompassed phases of diagnosis, intervention and evaluation. A comparative analysis between the companies was conducted: energy consumption versus product volume, energy-quality analysis, relation between compliance/specific energy consumption, and the impact on CO2 emissions. Results revealed that the acceptance to the recommendations of savings is biased by the level of investments and the willing/proneness of the administration. The study showed that interventions had a partial effect on the reduction of the specific energy consumption in 4 companies. In addition, it has obtained a positive effect on the power factor correction in one company and an improvement on the load balance in 5. The research showed the existence of a significant reduction of emissions post-intervention, highlighting the effectiveness of the programs.Ítem Stages in the development of a small hydropower project: context and implementation basic criteria(Universidad Nacional de Colombia Sede Medellín, 2014-04-24) Morales, Sergio; Corredor, Laura; Paba, Julio; Pacheco, LeonardoThe purpose of this article is to review and analyze the context and basic requirements to be considered to implement projects of Small Hydro Power, which was performed by collecting information and reviewing of the current state of technology in the country and worldwide, as well as the most efficient and suitable technologies for its implementation. Finally, it raises some stages and engineering studies to follow for successful development of an SHP project and defines the relevant conclusions of the analysis.Ítem Nonlinear time series forecasting using mars(Universidad Nacional de Colombia Sede Medellín, 2014-04-21) Velásquez Henao, Juan David; Franco Cardona, Carlos Jaime; Camacho, Paula AndreaOne of the most important uses of artificial neural networks is to forecast non-linear time series, although model-building issues, such as input selection, model complexity and parameters estimation, remain without a satisfactory solution. More of research efforts are devoted to solve these issues. However, other models emerged from statistics would be more appropriated than neural networks for forecasting, in the sense that the process of model specification is based entirely on statistical criteria. Multivariate adaptive regression splines (MARS) is a statistical model commonly used for solving nonlinear regression problems, and it is possible to use it for forecasting time series. Nonetheless, there is a lack of studies comparing the results obtained using MARS and neural network models, with the aim of determinate which model is better. In this paper, we forecast four nonlinear time series using MARS and we compare the obtained results against the reported results in the technical literature when artificial neural networks and the ARIMA approach are used. The main finding in this research, it is that for all considered cases, the forecasts obtained with MARS are lower in accuracy in relation to the other approaches.Ítem Methodology for distribution centers location through multicriteria analysis and optimization(Universidad Nacional de Colombia Sede Medellín, 2014-04-22) Soto-de la Vega, Diego Armando; Vidal-Vieira, José Geraldo; Vitor-Toso, Eli AngelaThis paper presents a combined methodology based on multicriteria decision analysis and optimization for the distribution centers location problem. The initial approach consists of a set of relevant quantitative and qualitative attributes used for the decision of locating distribution centers. From quantitative criteria a multi-objective mathematical programming model to minimize costs is proposed. This model provides alternative solutions that may be compared to the other ones initially known. These solutions are assessed for a multicriteria decision model which incorporates qualitative considerations of the problem that are infeasible to represent algebraically. Therefore, the application of the multi-criteria decision analysis model evaluates a set of feasible solutions to suggest for the best alternative considering several attributes.Ítem Effects of human-structure interaction in slabs(Universidad Nacional de Colombia Sede Medellín, 2014-04-24) Villamizar, Sandra; Gómez, Daniel; Thomson, PeterDuring the last several decades, stronger and lighter materials have been developed with the aim of optimizing performance and building costs. These technological advances have given rise to thin flexible flooring systems with natural frequencies that lie within the frequency range of vibrations produced by human activity. Human occupants can cause changes in the dynamic properties of the structure and structural vibrations can cause discomfort to the occupants, who not only perceive the vibrations but also interact dynamically with the structure. This paper presents the results of the characterization of the effect of human-structure interaction (HSI) in three flooring systems commonly used in the Colombian building industry. The methodology consisted in the characterization of the dynamic response of the flooring systems due to different coordinated human activities. Based on the results, the authors recommend that future building codes account for human-structure interaction effects in flooring systems.Ítem Microbicidal effect of solar radiation (sodis) combined with artemisia annua(Universidad Nacional de Colombia Sede Medellín, 2014-04-23) Muñoz Restrepo, Mariana; Orrego Mejia, Leidy Viviana; Muñoz Arango, Diana Carolina; Lozano Andrade, Carlos Neftaly; Guzman Ortiz, Diana Carolina; Escobar Restrepo, Maria Cecilia; Arcos Arango, Yamilet; Aguirre Ramirez, Nestor Jaime; Lutgen, Pierre; Mejía Ruiz, RobertoThis study evaluates the SODIS and SODIS method combined with Artemisia annua (SODIS+A. annua) as an alternative for water disinfection in communities without access to potable water. The efficiency of the method in removing E. coli, B. subtilis, E. faecalis and S. typhimurium was determined using PET bottles with sterile distilled water and an initial concentration of 1x106 UFC/ml of each microorganism. For SODIS+A. annua a 10% (v/v) infusion of A. annua was added; the bottles were exposed to sunlight for at least 6 hours and three variables (water temperature, solar radiation and turbidity) were measured. It was found that SODIS treatment was more efficient in the removal of the four microorganisms than SODIS + A. annua. The removals were higher after four hours of exposure to the bacterial species in their vegetative state.Ítem Ionic liquids (il) corrosion on a285 carbon steel(Universidad Nacional de Colombia Sede Medellín, 2014-04-24) Dos Santos, Rogério F.; Falcade, Tiago; Antonini, Leonardo M.; Ortega-V., María R.; Mattedi, Silvana; Iglesias, Miguel; Malfatti, Célia F.In this work, corrosion caused by different ionic liquids on Grade A – A285 carbon steel plates at room temperature (25°C) is studied. Ionic liquids were prepared via acid – base neutralization. The ionic liquid hydrophilic or hydrophobic character was determined by the wettability technique. Corrosion behavior for each system was analyzed by electrochemical measurements (open circuit potential monitoring and potentiodynamic polarization). Substrate morphology was analyzed by scanning electron microscope and energy dispersive X-ray spectroscopy before and after the electrochemical measurements. The results obtained showed that Grade A – A285 carbon steel in contact with the ionic liquids presented low corrosion rates, being the highest one the corresponding for the 2- hydroxyethylamominum lactate system and the lowest corrosion rate for 2-hydroxyethylammonium acetate system.Ítem The measurement of maintenance function efficiency through financial kpis(Universidad Nacional de Colombia Sede Medellín, 2014-04-23) Galar Pascual, Diego; Berges, Luis; Lambán, Mª Pilar; Tormos, BernardoThe measurement of the performance in the maintenance function has produced large sets of indicators that due to their nature and disparity in criteria and objectives have been grouped in different subsets lately, emphasizing the set of financial indicators. To generate these indicators properly is necessary to have accurate input data. Hence in this paper we propose a comprehensive model of consensus between the different stakeholders involved in the maintenance function. This will bring about the accurate determination of the maintenance costs of an organization.