Revistas UTB ( Universidad Tecnológica de Bolívar)
Not a member yet
353 research outputs found
Sort by
Sobre la (im)posibilidad del orden social espontáneo como mecanismo rector de las sociedades de mercado
Full text linkHayek and the Evolution of Capitalism, Naomi Beck Chicago: University of Chicago Press, 2018, 208 p.Hayek and the Evolution of Capitalism, Naomi Beck Chicago: University of Chicago Press, 2018, 208 p
Construction and Simulation of a Planar Transformer Prototype
Full text linkThis paper illustrates the design and building of a planar transformer prototype with a 1:1 transformation ratio for high-frequency applications in power electronics. By using reference literature and considering the ferrite core dimensions, the windings were conceived and exported to Gerber format using PCB design software. The transformer prototype was then assembled and tested under laboratory conditions for frequencies from 800 Hz to 5 MHz, which showed a sinusoidal wave at the transformer output from 1.3 kHz onwards and a better performance starting at 10 kHz, where the loses were significantly reduced and the transformation ratio was closer to the originally designed. As a final step, a finite element method (FEM) analysis was carried out to understand the electromagnetic flux behavior using a 3D Multiphysics simulation software. The 3d building process and details are explained step by step and the resulting magnetic flux density is graphically shown for the core and the windings.This paper illustrates the design and building of a planar transformer prototype with a 1:1 transformation ratio for high-frequency applications in power electronics. By using reference literature and considering the ferrite core dimensions, the windings were conceived and exported to Gerber format using PCB design software. The transformer prototype was then assembled and tested under laboratory conditions for frequencies from 800 Hz to 5 MHz, which showed a sinusoidal wave at the transformer output from 1.3 kHz onwards and a better performance starting at 10 kHz, where the loses were significantly reduced and the transformation ratio was closer to the originally designed. As a final step, a finite element method (FEM) analysis was carried out to understand the electromagnetic flux behavior using a 3D Multiphysics simulation software. The 3d building process and details are explained step by step and the resulting magnetic flux density is graphically shown for the core and the windings
Control de un cargador de baterías para vehículos eléctricos con factor de potencia unitario
Full text linkA nonlinear controller for an electric vehicle battery charger is proposed in this work. The controller allows charging the battery bank with constant current and constant voltage charging profile, while ensuring unity power factor and low distortion in the grid current. A single model is made for the complete system and the controller is designed using interconnection and damping assignment. The proposed controller ensures the closed-loop stability and allows decoupling the system avoiding disturbances in the electric grid and battery bank. The proposal is validated with simulation results.En este trabajo se presenta una estrategia de control no lineal para un cargador de baterías de vehículos eléctricos. El controlador propuesto permite realizar la recarga del banco de baterías mediante un perfil de carga a corriente y tensión constante mientras que asegura factor de potencia unitario y baja distorsión en la corriente de red. Se realiza un modelo único para todo el sistema a partir del cual se diseña el controlador utilizando asignación de interconexión y amortiguamiento. Esta estrategia asegura un controlador estable a lazo cerrado y permite desacoplar el sistema evitando que las perturbaciones del lado de la red afecten la carga de la batería y viceversa. La propuesta es validada mediante resultados de simulación
Evolución de las finanzas públicas de Cartagena, 2001 – 2018: ¿Se requiere mayor eficiencia en el recaudo?
Full text linkThis paper presents a descriptive analysis of the evolution of Cartagena's income, expenses and public debt between 2001 and 2018 in light of the government crisis experienced in the last seven years of that period. The results show that tax revenues maintained their growth rate despite the crisis. In contrast, the rate at which public spending grew was lower, specifically the one destined for investment. The results of an additional income projection exercise show that to generate the resources that could help finance the projects that the city requires, a higher effective collection is needed compared to the potential one.Este trabajo expone un análisis descriptivo de la evolución de los ingresos, gastos y deuda pública de Cartagena entre 2001 y 2018 a la luz de la crisis gubernamental experimentada en los últimos siete años de ese período. Los resultados indican que los ingresos fiscales mantuvieron su ritmo de crecimiento a pesar de la crisis. En contraste, el ritmo al que creció el gasto público fue menor, específicamente aquel destinado a inversión. Los resultados de un ejercicio adicional de proyección en los ingresos muestran que para generar los recursos que podrían ayudar a financiar los proyectos que requiere la ciudad se necesita de una mayor recaudación efectiva frente a la potencial
A Methodology to Calculate the Non-Supplied Energy Level in Distribution Grids With Radial Structure
Full text linkThe distribution agents of electrical energy have a commitment with the end customers to comply with certain reliability indices in order to guarantee the quality of the service they provide, among these, one of the most important is to maintain continuity in the electrical supply. This article presents a methodology with a possible application to real electrical distribution systems for calculating the level of unserved energy through the use of the concepts of operational zones and unavailability, through the analysis of failures in each of the different lines. and subsequent outages that occur in the test system. Different scenarios and configurations are evaluated by varying the position of reclosers and fuses in order to present the results and the corresponding conclusions
El desarrollo de la industria azucarera en el Valle del Cauca, Colombia, 1901 - 2015
Full text linkDuring the XXth century, a group of agribusiness entrepreneurs from Valle del Cauca built, using different strategies, one of the most succesful business sectors in Colombia. The owners of factories in Valle del Cauca, leaders in sugar production, have expanded their investment portfolio by creating agribusinesses in other regions of the country and in other Latin American countries. Today, the Colombian sugar industry is one of the productive complexes with the most influence over the economic and social development of Valle del Cauca and Colombia. This paper is a synthesis of the main stages in that long-term development, underlining those that have been key to the productivity, returns, and sustainability of the sugar industry in the XXth century.En el transcurso del siglo XX, un grupo de empresarios agroindustriales del Valle del Cauca construyó, a través de distintas estrategias, uno de los sectores empresariales más exitosos en Colombia. Líderes en la producción azucarera, los dueños de ingenios del Valle del Cauca han expandido su portafolio de inversiones con la creación de agroindustrias en otras regiones del país y en otros países de América Latina. Hoy la industria azucarera colombiana es uno de los complejos productivos de mayor influencia en el desarrollo económico y social de la región y de Colombia. Este trabajo es una síntesis de las principales etapas que se detectan en ese desarrollo secular, subrayando aquellas estrategias que han sido claves en la productividad, el rendimiento y la sostenibilidad de industria del azúcar en el siglo XX
Un nuevo contexto para el debate sobre el crecimiento económico colombiano
Full text linkReseña del libro "Ensayos sobre crecimiento económico en Colombia" de Adolfo Meisel Roca y Hernando Vargas Herrera (editores). Bogotá: Banco de la República, 2018, 244 p
Análisis de estabilidad de convertidores de segundo orden con la metodología de optimización de suma de polinomios cuadráticos
Full text linkThis paper presents a non-linear method based on sum-of-squares (SOS), to determine the stability of equilibrium points for the Buck, Boost, Buck-Boost and non-inverter Buck-Boost converters. These converters share a similar structure with a PI controller to regulate the output voltage. A quadratic Lyapunov function is proposed in all cases, and the conditions for stability are evaluated using convex optimization based on SOS models. The methodology is useful for academic purposes but also in practical applications like DC microgrids. Simulation results shows the advantages of the proposed method.This paper presents a non-linear method based on sum-of-squares (SOS), to determine the stability of equilibrium points for the Buck, Boost, Buck-Boost and non-inverter Buck-Boost converters. These converters share a similar structure with a PI controller to regulate the output voltage. A quadratic Lyapunov function is proposed in all cases, and the conditions for stability are evaluated using convex optimization based on SOS models. The methodology is useful for academic purposes but also in practical applications like DC microgrids. Simulation results shows the advantages of the proposed method
"El mercado" y la frágil retórica libertaria
Full text linkReseña del libro "The Market" de Matthew Watson. Newcastle: Agenda Publishing, 2018, 174 p
Concesiones viales de cuarta generación (4G): Una estimación de su impacto económico y social
Full text linkThis paper concerns a set of methodologies and applications, as a case study to measure the economic and social consequences of implementing fourthgeneration (4G) road licenses in Colombia. For the economic estimates, we used Leontief Multipliers derived from the Input Output Matrix which is put together for the case study of the Disaggregated Utilization Matrix in National and Imported Products reported by DANE. These multipliers allow the estimation of the projects’ contribution to economic growth. The social effect is analyzed using the Monetary Poverty Index and the Multidimensional Poverty Index using the information reported in the Large Integrated Household Survey. As a case study for the application of the methodology, the Santana–Puerto Salgar corridor located in Colombia is used. The results generated by the Leontief Multipliers allow us to calculate that for each COP2.52 is generated in gross terms and COP1,0 invertido en las concesiones 4G, se generan COP1,52 en términos netos. Este efecto multiplicativo genera un aporte al crecimiento del PIB nacional del 0,27%, 0,17% y 0,01% para los años 2018, 2019 y 2020 respectivamente, durante la etapa de construcción, y 0,04% anual entre 2022 y 2024 durante la etapa de operación del corredor. El impacto social se cuantificó mediante la reducción del número de personas pobres en los departamentos afectados; se espera una reducción del Índice de Pobreza Monetaria de 32,1% a 23,2% durante la etapa de construcción y operación, y una reducción de 12,4% a 10,2% del Índice de Pobreza Multidimensional para el mismo periodo