Enfoque UTE

pp. 154 - 167

Authors: Verónica Machado, Roberto Granda, Alexandra Endara González

An aquatic macroinvertebrates community analysis was made at Sardinas River, in the rainy and wet seasons of 2018, using macroinvertebrates as environmental bioindicators; these were collected with Surber net and hand collection, in five points along the river. In the laboratory they were classified and identified as class, order and family. They were studied by the analysis of richness (S) and abundance (N). The environmental quality was determinate applying the BMWP/Col and EPT indices. A total of 526 individuals belonging to 15 orders and 44 families were collected. 35 in the rainy season and 31 in the dry season. The most abundant family in rainy season was Leptophlebiidae, 34 specimens (12.8%). In dry season, the most representative was Chironomidae with 45 individuals (17.2%). In rainy season the point 2 had greater richness S16 and in the dry season P1, S18. P3 - P5 presented medium quality water (BMWP/Col = 69-94 and an EPT average of 47.05%). This study determined through BMWP/Col and EPT indices, in association with the taxa collected and the calculations of (S), (N) and relative abundance (%), the ecological status of the studies’ area.

pp. 131 - 144

Authors: R León, Beatriz Margarita Pernía Santos, Rosa Siguencia, S Franco, A Noboa, Xavier Cornejo

In Ecuador, many communities depend on untreated surface water as the primary source of drinking water and are contaminated with fecal coliforms and Escherichia coli. The objective of the present study was to find aquatic plants with remove of contaminated water with E. coli and total coliforms. For this purpose, the following species were sampled: Azolla caroliniana Willd., Eichhornia crassipes, Pistia stratiotes, Salvinia auriculata, Ceratopteris thalictroides and Lemna sp. (Positive control). The plants were reproduced in vitro and bioassays were performed to verify their ability to remove E. coli. Assays were run by triplicate in 0.5 L of water with fertilizer and an E. coli ATCC25922 reference strain was inoculated. As negative control the bacteria without plants and positive control were inoculated with the plant L. minor. After 7 days, the remaining bacterial load was determined. To analyze E. coli, the technique ISO 9308-1 was used. A percentage of 99% E. coli removal was found for A. caroliniana, E. crassipes, C. thalictroides (L.) Brongn and Lemna minor. And 100% for P. stratiotes and S. auriculata. Subsequent waste water tests were performed in which S. auriculate and A. caroliniana achieved 100% removal of the coliforms and the remaining lower efficiency. The use of these species is proposed for the treatment of wastewaters.

pp. 110 - 119

Authors: Maribel Cecilia Pérez Pirela, Juan Paulo García Sandoval

Sliding modes control (SMC) is a nonlinear control method with a systematic design procedure that allows to obtain a explicit solution for the control input. This method has some advantages, such as robustness against external disturbances and unpredictable parametric variations. On this work, two conventional SMC techniques, one using the error and other using the error integral, are designed and validated in a heat exchange system composed of a single pass circulation electric heater, whose control objective is to regulate the output temperature of the fluid, under the influence of external disturbances, such as variations in the flow and inflow temperature, manipulating the electric current passing through the heater resistance. The two SMC algorithms are analyzed using numerical simulations and their performance is compared through the integral absolute error and the integral absolute control input, selecting the best one to be tested experimentally. The experimental results indicate that the SMC is capable of fulfilling the control objective with satisfactory performance.

pp. 77 - 87

Authors: Raúl Esteban Alzate, Diego Martinez, Juan Carlos Mena, Bernado Sabogal, Jimmy Tombe

Los controladores MPC son buenos eliminando el error de estado estacionario aun si el sistema controlado es afectado por perturbaciones. Pero el MPC no fue pensado para mantener su desempeño bajo condiciones de falla por sí solo. El control tolerante a fallas se compone de algoritmos de control, estrategias de detección y compensación de fallas. En este trabajo se implementó un controlador MPC usando la estrategia de matriz dinámica junto con un generador de residuo basado en modelo para detectar la ocurrencia de una falla en el sistema controlado. La cuantificación de fallas se logró mediante el uso de Redes neuronales artificiales y un filtro pasa banda, lo cual permitió realizar una acción de compensación para mejorar el tiempo de recuperación del sistema ante una falla.

pp. 57 - 68

Authors: José Saúl Muñoz Reina, Miguel Gabriel Villarreal Cervantes, Leonel German Corona Ramirez, Robero Castro Medina

The rehabilitation given by robotic systems is a choice for minimizing the recovery time of a patient and boost their muscular and skeletal capacity on a limb damaged. However, the high cost of these systems limits patients to receive these kind of treatments. The systems of one degree of freedom are a low cost alternative to health care and rehab at home. In this paper, the structural design of an 8-link mechanism for the rehabilitation of lower limbs is performed, based on the approach and solution of an optimization problem in which certain objectives are met, such as dimensional synthesis, and the minimizing of torque to make control easier.

pp. 33 - 44

Authors: Saul Enrique Benitez-Garcia, Miguel Gabriel Villarreal-Cervantes

In the classical approach of Time-Triggered Control (TTC), the control signal is updated at each sampling time as well as the system states to be controlled, which could imply a redundancy in the computational calculation as well as in the transfer of information in the regulation objective. On the other hand, the Event-Triggered Control (ETC) approach performs the same task in an asynchronous way, i.e,, it only updates the control signal when a performance requirement is violated and the states are updated at each sampling time. This reduces the amount of computational calculation without affecting the performance of the closed loop system. For this reason, in the present work the ETC is developed for the stabilization of a manipulator robot with three Degree of Freedom (DoF) in the joint space where a Lyapunov Control Function (LCF) is proposed to formulate the event function (e¯), which indicates whether or not is required the control signal updating. Simulation results show the reduction of the updates compared with a TTC.

pp. 13 - 23

Authors: Jhon Alexander Isaza Hurtado, Diego A Muñoz, Hernán Álvarez

This work presents an alternative method to solve the nonlinear program (NLP) for nonlinear model predictive control (NMPC) problems. The NLP is the most computational demanding task in NMPC, which limits the industrial implementation of this control strategy. Therefore, it is important to consider algorithms that can solve the nonlinear program, not only in real time but also guaranteeing feasibility. In this work, the restricted enumeration method is proposed as alternative to solve the NLP for NMPC problems, showing successful results for pH control in a sugar cane process plant. This method enumerates in restricted way a set of final control element possible positions around the current one. Next, it tests all positions in that set to find the best one, taken as the optimization solution.

pp. 221 - 232

Authors: Edilberto Antonio Llanes Cedeño, José Bolívar Carguachi-Caizatoa, Juan Carlos Rocha-Hoyos

This paper aimed to evaluate the behavior of an Otto Cycle internal combustion of a 1.6 L engine measuring its performance by the energy and exergy balance. The energy calculation was developed in a previously set route at a constant speed of 50 km/h and 90 km/h. It was determined, that the analysis of the energy and exergy balance contributes to recognize the performance of an internal combustion after the experimentation based on observation, measurement, methods of induction, deduction and synthesis. Also, it was resolved that the engine has an average energy efficiency of 27.57 % for a speed of 50 km/h, while the total exergy flow of the system is 22 %. Therefore, there is no significant difference with the efficiency results at 90 km/h.

pp. 208 - 220

Authors: Alex Rodolfo Guzmán, Eduardo Cueva, Alexander Peralvo, Milton Revelo, Alexis Armas

he purpose of this study is to compare and examine the performance of an engine, using gasoline with 92 octanes (Super), 87 octanes (Extra) and two volume mixtures of these two types of gasoline, the first one had 50% of volume of each type, the second one had a volume value of 70% of Super with 30% of Extra. To evaluate the performance of the engine, a dynamometer was used to obtain the characteristics curves of power and torque, a gas analyzer was used to determine the level of emission of pollutant gases from the engine (CO, CO2, HC, y NOx), finally an homologated cycle was carried out to measure fuel consumption. The mixture of Super 50% with Extra 50% obtained a higher power value with 81.3 HP, the Super gasoline obtained a higher torque value of 89.2 lb-ft, in cycle ASM 2525, the CO, HC and NOx were measured, the Super gasoline, Extra gasoline and the mixture of 50% of each gasoline were the least polluting ones, in cycle ASM 5015, CO, HC and NOx were measured, Super gasoline, Extra and the Super 70% V mixture with Extra 30% V respectively were less polluting, in the static gas test the least polluting was Super.

pp. 88 - 98

Authors: Ruth Cueva, Diego Salazar, Gabriel Francisco Grijalva

Throughout this paper we seek to demonstrate the practicality of obtaining an approximate model of the relationship between a score that determines the learning styles of a student and the results obtained in a specific University-level lecture. The study considered the voluntary participation of over six hundred students from “Escuela Politécnica Nacional” of Ecuador (EPN). The Index of Learning Styles model was used to establish the various learning styles of the students. The analysis of the results considers the linear correlation and the correlation distance.