Universidad Tecnológica de Bolívar
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Application of the Generalized Normal Distribution Optimization Algorithm to the Optimal Selection of Conductors in Three-Phase Asymmetric Distribution Networks
No full textThis article addresses the problem of the optimal selection of conductors in asymmetric three-phase distribution networks from a combinatorial optimization perspective, where the problem is represented by a mixed-integer nonlinear programming (MINLP) model that is solved using a master-slave (MS) optimization strategy. In the master stage, an optimization model known as the generalized normal distribution optimization (GNDO) algorithm is proposed with an improvement stage based on the vortex search algorithm (VSA). Both algorithms work with discrete-continuous coding that allows us to represent the locations and gauges of the different conductors in the electrical distribution system. For the slave stage, the backward/forward sweep (BFS) algorithm is adopted. The numerical results obtained in the IEEE 8- and 27-bus systems demonstrate the applicability, efficiency, and robustness of this optimization methodology, which, in comparison with current methodologies such as the Newton metaheuristic algorithm, shows significant improvements in the values of the objective function regarding the balanced demand scenario for the 8- and 27-bus test systems (i.e., 10.30% and 1.40% respectively). On the other hand, for the unbalanced demand scenario, a reduction of 1.43% was obtained in the 27-bus system, whereas no improvement was obtained in the 8-bus grid. An additional simulation scenario associated with the three-phase version of the IEEE33-bus grid under unbalanced operating conditions is analyzed considering three possible load profiles. The first load profile corresponds to the yearly operation under the peak load conduction, the second case is associated with a daily demand profile, and the third operation case discretizes the demand profile in three periods with lengths of 1000 h, 6760 h, and 1000 h with demands of 100%, 60% and 30% of the peak load case. Numerical results show the strong influence of the expected demand behavior on the plan’s total costs, with variations upper than USD/year 260,000.00 between different cases of analysis. All implementations were developed in the MATLAB® programming environment. © 2023 by the authors
Biografía Justo Almario: Audio 7. Testimonio de Almario sobre su estudio con Jorge Rafael Acosta
No full textSi bien Justico estaba contento en su nuevo hogar, y tenía pocos vínculos con su familia materna, en ocasiones, quizás en vacaciones, viajaba a Sincelejo, manteniendo el contacto con su abuela y de paso con las músicas y músicos, como Pello Torres.
“Y me acuerdo que yo cuando tenía 10 años estaba
tocando, ya estaba tocando, tú sabes, con él, y él tocaba el bombardino, tocábamos duetos, y la música que tocábamos era música colombiana de la costa Atlántica: cumbias, porros, chandés, pero también tocábamos bambucos y pasillos. Bambucos y pasillos es la música del interior de Colombia que es en ¾, 6 por 8, y él se ponía a tocar con su bombardino, tú sabes: “po ro, pi ro pi pa pa, pi ro pi pa pa, [tararea figuras acompañantes en tres cuartos para el bombardino]”, como un bajo, ¿ves?, y entonces me decía: “ok, Justico, toca, toca, estamos en Re menor, arranca”. Y él, claro, lo mantenía siempre en tónica y dominante, y a veces se iba para un cuarto grado”
Love Thy Neighbor: La Vida Musical De Justo Almario
No full textRoy Ayers era en ese entonces un artista de gran renombre por lo cual los conciertos, giras y grabaciones abundaban. Justo estuvo con él de 1976 a 1979, periodo en el que intervino en cinco de sus producciones, como parte de su agrupación Ubiquity.53 Estos discos fueron grabados en Nueva
York, con el sello Polydor; sin embargo, Roy le “vendió” el grupo al sello Elektra/Asylum, en Los Ángeles y, en consecuencia, la banda completa se mudó a dicha ciudad para grabar tanto a nombre propio como
con diferentes artistas. Una vez más, Justo cambió su ciudad de residencia
Desarrollo e implementación de un perfilómetro óptico por triangulación láser
No full textProfilometers are instruments commonly used in surface metrology tasks. These instruments play a key role in the industry, such as in manufacturing and quality assurance. However, conventional profilometry techniques require direct contact with the object. In this work, we developed a practical and low-cost optical profilometer for contactless profilometry. The proposed profilometer is based on a laser triangulation system. A laser spot is projected onto the surface of an object, which is captured by a camera. The images are processed to detect the laser spot's location and obtain the object's surface height through calibration. We designed and built the translation stage to process the object's surface. Finally, encouraging results show that the profilometer provides high accuracy with fast acquisition. © 2020 IEEE
Diferencias de género en matemáticas y lengua: Rendimiento académico, autoconcepto y expectativas
No full textPrevious studies show gender differences in math and language performance, mainly in adolescents. In this study, we aim to evaluate gender differences in self-concept, subjective value, expectations and academic performance, to analyze the relationships between the variables, and to understand their role in explaining performance in language and mathematics. A total of 406 4th and 5th grade students from Colombia participated in this study. The results show that girls have higher performance expectations in mathematics and language, as well as higher performance in language than boys. No gender differences were found in self-concept and the subjective value of the task. Self-concept, performance expectations and age explained performance in both mathematics and language. We discuss the implications of these results for narrowing the gender gap in learning. Because this study is the first attempt to explore the relationships between expectations and task-value beliefs in language and mathematics in Hispanic primary school students based on the Expectancy-Value Model, more research is needed to support or refute our findings. © 2020 Fundación Universitaria Konrad Lorenz.Previous studies show gender differences in math and language performance, mainly in adolescents. In this study, we aim to evaluate gender differences in self-concept, subjective value, expectations and academic performance, to analyze the relationships between the variables, and to understand their role in explaining performance in language and mathematics. A total of 406 4th and 5th grade students from Colombia participated in this study. The results show that girls have higher performance expectations in mathematics and language, as well as higher performance in language than boys. No gender differences were found in self-concept and the subjective value of the task. Self-concept, performance expectations and age explained performance in both mathematics and language. We discuss the implications of these results for narrowing the gender gap in learning. Because this study is the first attempt to explore the relationships between expectations and task-value beliefs in language and mathematics in Hispanic primary school students based on the Expectancy-Value Model, more research is needed to support or refute our findings. © 2020 Fundación Universitaria Konrad Lorenz
Biografía Justo Almario: Audio 15. Tema Cumbia Del Monte (Marco A. Posada)
No full textAquí se aprecia que su estilo tiene tanto de música del Caribe colombiano como de las técnicas de arreglos, interpretación y el formato instrumental de las big bands tanto del jazz estadounidense como de las orquestas de la Cuenca del Caribe.
Como ejemplo de esto, vemos que el ritmo, el formato, el
fraseo, y la armonía modal son convenciones de las orquestas del Caribe colombiano de la época. Algunos voicings, como el acorde final, son más habituales en las orquestas cubanas y de la Cuenca del Caribe. La presencia del jazz es evidente tanto en la orquestación como en el uso del cromatismo de la melodía y el énfasis que hace en el quinto
grabo bemol utilizado aquí como una blue not
Tecnología de reciclaje químico sostenible para la descomposición de poliestireno expandido (EPS) mediante el uso de solventes ecológicos
No full textEste proyecto se centra en la búsqueda de soluciones sostenibles para enfrentar el desafío ambiental del reciclaje de poliestireno expandido (EPS), conocido como icopor. Dado su uso masivo en la industria de envases y su bajo índice de reciclaje, el EPS representa un problema significativo para el medio ambiente. En Cartagena, los residuos de EPS desechados por los restaurantes contribuyen a la contaminación de vertederos y cuerpos de agua. Para abordar esta problemática, desarrollamos un método de reciclaje químico utilizando d-limoneno, un solvente verde extraído de los cítricos. Este enfoque no solo maximiza la recuperación del EPS, sino que permite transformarlo en nuevos productos, promoviendo así la economía circular y reduciendo la huella ambiental. El proceso de reciclaje químico que proponemos, aunque más costoso que los métodos tradicionales, es una solución rentable a largo plazo, ya que cumple con estrictas normativas de ingeniería y genera valor económico a partir de residuos plásticos. Además, educa y sensibiliza a la comunidad local sobre la importancia del reciclaje y la sostenibilidad. Este proyecto demuestra que el EPS, un recurso comúnmente desechado, puede ser reintegrado a la cadena de suministro, beneficiando tanto al medio ambiente como a la economía de la región.Universidad Tecnológica de BolívarIngeniero QuímicoPregrad
Desarrollo de un Gateway I-IoT para Modbus TCP/IP
No full textEste trabajo presenta el desarrollo de un Gateway IoT, el cual permite la interacción entre un dispositivo con salida en protocolo Modbus TCP y un servidor con conexión a Internet. El Gateway es probado usando un equipo Sentronpac 3200 interconectado a una aplicación en Ubidots. Los resultados muestran la viabilidad de la implementación y las pruebas finales realizadas fueron exitosas, aunque solo se probó el caso unidireccional.Universidad Tecnológica de BolívarIngeniero MecatrónicoPregrad
[Aprendizaje del uso terapéutico de fármacos a partir de la información espacial tridimensional de su estructura molecular con redes neuronales convolucionales
No full textAbstract
The development of new molecules is a multi-stage process and clinical trials to verify their efficacy cost billions of dollars each year. Machine learning is a tool that is rapidly advancing in image, voice, and text recognition, and working in silico would increase the ability to predict and prioritize a drug's function. In this research we asked whether the function of therapeutic drugs can be predicted from the stereochemical configuration of the molecule. We use convolutional neural networks to predict the therapeutic use of drugs, trained with both two-dimensional and three-dimensional information of their chemical structure. The model trained with only six views of the 3D information of the molecular structure improved the accuracy by 10 over the model trained with the 2D information. © 2021, Universidad Nacional de Colombia. All rights reserved
Adaptive Sensorless PI+Passivity-Based Control of a Boost Converter Supplying an Unknown CPL
No full textThis paper presents an adaptive control to stabilize the output voltage of a DC–DC boost converter that feeds an unknown constant power load (CPL). The proposed controller employs passivity-based control (PBC), which assigns a desired system energy to compensate for the negative impedance that may be generated by a CPL. A proportional-integral (PI) action that maintains a passive output is added to the PBC to impose the desired damping and enhance disturbance rejection behavior, thus forming a PI+PBC control. In addition, the proposed controller includes two estimators, i.e., immersion and invariance (I&I), and disturbance observer (DO), in order to estimate CPL and supply voltage for the converter, respectively. These observers become the proposed controller for an adaptive, sensorless PI+PBC control. Phase portrait analysis and experimental results have validated the robustness and effectiveness of the adaptive proposed control approach. These results show that the proposed controller adequately regulates the output voltage of the DC–DC boost converter under variations of the input voltage and CPL simultaneously. © 2022 by the authors