Tecnura

29-40

Authors: Juan Miguel Astorga Gómez, Rodrigo Alfonso Aróstica Córdova, Yuri Antonio Iriarte Salinas

Background: Due to massive incorporation of electronic equipment to distribution systems, distribution transformers are subject to operation conditions other than the design ones, because of the circulation of harmonic currents. It is necessary to quantify the effect produced by these harmonic currents to determine the capacity of the transformer to withstand these new operating conditions. The K-factor is an indicator that estimates the ability of a transformer to withstand the thermal effects caused by harmonic currents. This article presents a linear regression model to estimate the value of the K-factor, from total current harmonic content obtained with low-cost equipment. Method: Two distribution transformers that feed different loads are studied variables, current total harmonic distortion factor K are recorded, and the regression model that best fits the data field is determined. To select the regression model the coefficient of determination R2 and the Akaike Information Criterion (AIC) are used. With the selected model, the K-factor is estimated to actual operating conditions. Results: Once determined the model it was found that for both agricultural cargo and industrial mining, present harmonic content (THDi) exceeds the values that these transformers can drive (average of 12.54% and minimum 8,90% in the case of agriculture and average value of 18.53% and a minimum of 6.80%, for industrial mining case). Conclusions: When estimating the K factor using polynomial models it was determined that studied transformers can not withstand the current total harmonic distortion of their current loads. The appropriate K factor for studied transformer should be 4; this allows transformers support the current total harmonic distortion of their respective loads

53-67

Authors: Edward Julián Ramos Ballesteros, Gloria Margarita Varón Durán, Luis Carlos Méndez Córdoba

Context/Objectives: The objective is to design and implement a network of emulators in order to develop make a practical workshop in the future with students in the area of health, testing their knowledge and learn from the experienced before exercising their professional life. Method: The network is composed of a Central Control Module (CM), which allows teachers to create clinical scenarios, and three Emulators for students. Once created the scenarios, they are transmitted to a emulator that was chosen through a graphical interface, allowing the student to observe the values and signals of vital signs in both the physical part (ME: Dummy Emulator) and the graphic part (IE: Interface Emulator), and take action depending on the knowledge acquired in their studies. Then a response process is generated showing the results of actions to the teachers. Finally, the teacher makes a comparison of the clinical scenarios with the response, to evaluate the students and thus he also stimulates learning in them. Results: Implementation features after performing a series of tests are as follows: the maximum distances of the components with respect to MC, without losing optimum performance of network, is 8 meters for IE and 12 meters for the ME. In addition with techniques implemented, it is reduced by 13.28% runtime when programming the clinical scenario, and it is reduced by 21.78% runtime of response process, settling in 8.42 and 4.99 seconds respectively. Conclusions: Given the maximum distance and runtimes, the network of emulators is built with features necessary to implement a practical workshop in the future taking into account the technical specifications, traffic conditions, size of the classrooms, users in parallel and the frequency of used

89-99

Authors: Lina María Romero Millán, María Alejandra Cruz Domínguez, Fabio Emiro Sierra Vargas

Context: Taking into account that near 220 000 tons of oil palm shells are produced every year in Colombia, as a waste of the Elaeis Guineensis palm oil transformation process, the aim of this work is to determine the energy potential of oil palm shells, when transformed through slow pyrolysis process. Methods: Using a fixed bed lab scale reactor, different oil palm shells pyrolysis tests were performed between 300°C and 500°C. The effect of the temperature in the process product yield and in the energy content of produced solids and gases were analyzed. Results: With a maximum mass yield of 50%, the char is considered the main product of oil palm shells pyrolysis, containing up to 73% of the raw biomass energy. The heating value of char raised with the temperature, from 29,6 MJ/kg at 300°C to 31,34 MJ/kg at 500°C. Moreover, the gas produced in the established temperature range had up to 13% of the energy content of the raw biomass, with a heating value near 12,5 MJ/m3 . Conclusions: According to the results, slow pyrolysis can be considered an interesting process for the valorization of residual biomass as oil palm shells, through the production of solids and gases that can be used as fuels, or as precursor of other value-added products

115-121

Authors: Sergio Giovanny Valbuena Porras, Milton Mena Serna

Context: In a masonry wall the mortar it is between 10 and 20% of the total volume of the system, despite its effect on the behavior of it is significantly higher than this percentage indicates. Objective: The purpose of this research was to evaluate the resistance to compression of two types of mortar paste (A and B), prepared with natural sand from the town of Usme in Bogotá, in accordance with the proportions set by the Standard Colombian earthquake Resistant regulation (NSR-10). Method: Two types of mortar paste were prepared, according to the proportions of cement and sand established in NSR-10 section D.3.4-1 of (Table 1); these proportions were calculated using a 0.0028 m3 container for measuring unit weight. For type A mortar rock sand was used and river sand for type B mortar. Results: The resistance to compression for mortars type A at the end of the study was on average 84% of the expected resistance, whereas for type B mortars it averaged 64% above the expected resistance. Conclusion: Mortar mixes made with crushed or rock (type A) arena do not reach the compressive strength required demanded by regulatory standards, despite complying with the dosage established in NSR 10 and with NTC quality criteria; while the natural sand origin or natural river sand meet these standards

123-136

Authors: Germán Hernández Millán, Luís Hernando Ríos Gonzales, Maximiliano Bueno López

Context: Mobile robotics remains being an area of constant updating, which seeks to have applications to improve the life quality of human beings. Therefore, the paper presented a novel design of a position and move controller to a differential mobile robot using artificial neural networks, which aims is to bring a real applications in different fields. Method: The proposal is based on a PID controller, which has been tuned using a neural network and requires knowledge of the kinematic model of the robot Results: The simulations show the efficiency of the control position for following paths, in this case for tracking straight and curved paths. The graphical interface allows adjusting the gains easily and verifies the trajectory tracking online. Conclusions: From the results we can conclude that the proposed strategy is easy to implement since the required information is generally deliver by mobile robot sensors. Finally, tuning PID controller with the neural network allows obtaining a correct performance for trajectory tracking.

171-183

Authors: Luz Adriana Trejos Grisales, Carlos Andrés Ramos-Paja, Andrés Julián Saavedra-Montes

Context: The energy produced by photovoltaic (PV) systems operating under partial shading conditions depends on the connections between the modules and the shading pattern. Several mathematical models have been proposed to address this topic exhibiting different compromises between accuracy, calculation speed and PV model complexity. However, it is not evident how to choose a model for a given application to ensure reliable results. Method: Several mathematical models of PV systems under shading conditions were analyzed to synthetize the characteristics, advantages and drawbacks of each one of them. Three main categories have been identified: analytical, simulation and experimental methods. Analytical and simulation methods require a basic PV model and mathematical analysis supported by computational tools; while experimental methods are based in data or measurements. Results: From the analysis of the published solutions, three representative modeling techniques with different characteristics were selected to perform a practical comparison. Those techniques were implemented and contrasted in realistic scenarios to identify the effects of the compromise between accuracy, calculation speed and PV model complexity. Conclusions: To select a mathematical model it must be taken into account the connection scheme, model of the PV unit, model of the bypass and blocking diodes, size of the system, programming complexity and simulation time. This paper provides some guidelines to choose the right model for a particular application depending on those characteristics.