Universidad Tecnológica de Bolívar
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Active Films Based on Starch and Wheat Gluten (Triticum vulgare) for Shelf-Life Extension of Carrots
No full textThe use of biodegradable biopolymers with the incorporation of active ingredients has been considered as an alternative to extend the useful life of food. Therefore, the objective of this research was to develop active films based on starch and wheat gluten, containing cinnamon and turmeric essential oils by using the solvent casting method. Different film formulations were made from wheat starch, gluten, glycerol, and essential oils of cinnamon and turmeric. The films were characterized according to their morphology, optical, thermal, antioxidant, and barrier properties. Subsequently, the active properties on baby carrots regarding weight loss, appearance, and fungal growth were evaluated. The results indicated that the starch-based films showed a slight decrease in moisture content with the addition of essential oils (up to 13.29%), but at the same time showed a significant reduction in water solubility (up to 28.4%). Gluten-based films did not present significant differences in these parameters, although the solubility in water tended to increase (up to 13.15%) with the addition of essential oils. In general, the films presented good thermal stability and antioxidant capacity, and in the carrot coating test, a decrease in weight loss of up to 44.44% and 43.33% was observed for the coatings based on starch and gluten with the addition of turmeric essential oil, respectively. Finally, films developed with cinnamon and turmeric essential oils are potential candidates for the design of biodegradable active packaging. © 2022 by the authors
Optimal integration of D-STATCOM in distribution grids for annual operating costs reduction via the discrete version sine-cosine algorithm
No full textThis paper deals with the problem of the optimal placement and sizing of distribution static compensators (D-STATCOM) in electrical distribution networks to reduce the total annual operative costs associated with the total costs of energy losses added with the investment costs in D-STATCOM. The metaheuristic sine-cosine optimization algorithm determines nodes with the location and optimal sizes of the D-STATCOM. A discrete-continuous codification represents the decision variables, where the discrete part is entrusted with the best candidate nodes selection. The continuous part deals with the optimal sizes assigned to the D-STATCOM. Numerical results in the IEEE 33- and IEEE 69-bus systems demonstrate the effectiveness of this approach since it helps to minimize the total grid operation costs compared with the solution of the mixed-integer nonlinear programming model in GAMS. All the numerical validations are carried out in the MATLAB programming environment. © 2022 The Author
Representaciones de la medicina ancestral al bienestar social: caso Hato viejo Bolívar-Colombia
No full textLa humanidad desde sus orígenes enfrentó las enfermedades valiéndose de los recursos que ofrecía la naturaleza para sentirse en cuerpo y alma saludable. En América Latina y el Caribe, la medicina ancestral hace parte esencial de las tradiciones culturales de los pueblos indígenas y afrodescendientes, reconociéndose como patrimonio histórico y sociocultural por su valor y contribución al bienestar social de las comunidades, aquellas que desde su propia cosmovisión y en contacto con la naturaleza han acumulado de generación en generación saberes, prácticas y técnicas para colectivamente prevenir, atender, aliviar o curar enfermedades que afectan la salud. El estudio sobre “Representaciones de la medicina ancestral al bienestar social: caso Hato Viejo Bolívar-Colombia”, que aquí se acomete tiene como objetivo analizar las significaciones configuradas de la medicina ancestral al bienestar social por parte de los estudiantes de décimo grado de la Institución Educativa Técnica Agroindustrial: José Antonio Galán del corregimiento de Hato Viejo-Bolívar. El trabajo se encuentra organizado en cinco capítulos, que de manera secuencial y pormenorizada explica el proceso seguido en el desarrollo de la labor investigativa. El primer capítulo desarrolla lo relacionado con el problema, su planteamiento y descripción, la pregunta de investigación, los objetivos y la justificación del mismo. En el segundo capítulo, se aborda el marco de referencia del estudio, que incluye: los antecedentes investigativos (Internacionales, nacionales y regionales-locales) y los marcos teórico, legal y contextual. Por su parte, el tercer capítulo da cuenta de la metodología, integrada por enfoque, paradigma, tipo de investigación, población y muestra, técnicas e instrumentos para la recolección y análisis de la información. El cuarto capítulo, se dedica al análisis y presentación de resultados en torno a los objetivos de conocimiento propuestos, y por último, el quinto capítulo expone las conclusiones y recomendaciones derivadas del proceso investigativo.Universidad Tecnológica de BolívarMagíster en Métodos de Investigación SocialMaestrí
An Application of Machine Learning to Estimate and Evaluate the Energy Consumption in an Office Room
No full textThere are no exact criteria for the architecture of openings and windows in office buildings in order to optimize energy consumption. Due to the physical limitations of this renewable energy source and the lack of conscious control over its capabilities, the amount of light entering offices and the role of daylight as a source of energy are determined by how they are constructed. In this study, the standard room dimensions, which are suitable for three to five employees, are compared to computer simulations. DesignBuilder and EnergyPlus are utilized to simulate the office’s lighting and energy consumption. This study presents a new method for estimating conventional energy consumption based on gene expression programming (GEP). A gravitational search algorithm (GSA) is implemented in order to optimize the model results. Using input and output data collected from a simulation of conventional energy use, the physical law underlying the problem and the relationship between inputs and outputs are identified. This method has the advantages of being quick and accurate, with no simulation required. Based on effective input parameters and sensitivity analysis, four models are evaluated. These models are used to evaluate the performance of the trained network based on statistical indicators. Among all the GEP models tested in this study, the one with the lowest MAE (0.1812) and RMSE (0.09146) and the highest correlation coefficient (0.90825) is found to be the most accurate. © 2023 by the authors. Licensee MDPI, Basel, Switzerland
Politicídio de baixa intensidade: extermínio territorializado do Partido Revolucionário dos Trabalhadores (PRT) no Caribe colombiano, 1991-2005] [Politicidio de baja intensidad: exterminio territorializado del Partido Revolucionario de los Trabajadores (PRT) en el Caribe colombiano, 1991-2005
No full textObjective/Context: The following article analyzes the politicide of the Partido Revolucionario de los Trabajadores (PRT) after signing the peace agreement between this guerrilla group and the Colombian government in 1991. It shows how studies on genocides and politicides fall into an error that we call “quantity bias” in this article since they only consider large-scale exterminations of political groups, leaving out the analysis of exterminations carried out in a more selective and localized manner. Based on a critical review of the specialized literature, the study constructs a typology of different forms of political assassinations, deriving from it the concept of low-intensity politicide, proposed as the most appropriate category of analysis for the case study of the PRT. Methodology: A case study based on a documentary review and semi-structured interviews with former members of the PRT, FARC-EP, and AUC. Conclusions: Among the main findings, it is evident how low-intensity politicides, such as the one that occurred with the PRT, are characterized by being executed mainly through individual selective violence, having a local/regional geographic scope and their main perpetrators tending to be paramilitary groups in alliance with local elites and State agents. Originality: The theoretical contribution of the study consists of proposing a new category, such as low-intensity politicide, for the analysis of other cases of political extermination. It is also the first academic research focused on the extermination of the PRT. © 2022 Universidad de los Andes, Bogota Colombia. All rights reserved
Multi-Objective Dispatch of PV Plants in Monopolar DC Grids Using a Weighted-Based Iterative Convex Solution Methodology
No full textThe design of an efficient energy management system (EMS) for monopolar DC networks with high penetration of photovoltaic generation plants is addressed in this research through a convex optimization point of view. The EMS is formulated as a multi-objective optimization problem that involves economic, technical, and environmental objective functions subject to typical constraints regarding power balance equilibrium, thermal conductor capabilities, generation source capacities, and voltage regulation constraints, among others, using a nonlinear programming (NLP) model. The main characteristic of this NLP formulation of the EMS for PV plants is that it is a nonconvex optimization problem owing to the product of variables in the power balance constraint. To ensure an effective solution to this NLP problem, a linear approximation of the power balance constraints using the McCormick equivalent for the product of two variables is proposed. In addition, to eliminate the error introduced by the linearization method, an iterative solution methodology (ISM) is proposed. To solve the multi-objective optimization problem, the weighted optimization method is implemented for each pair of objective functions in conflict, with the main advantage that in this extreme the Pareto front has the optimal global solution for the single-objective function optimization approach. Numerical results in the monopolar version of the IEEE 33-bus grid demonstrated that the proposed ISM reaches the optimal global solution for each one of the objective functions under analysis. It demonstrated that the convex optimization theory is more effective in the EMS design when compared with multiple combinatorial optimization methods. © 2023 by the authors
Diseño e implementación de un sistema de comunicación simplex acústico submarino para operar en la capa superficial de la bahía de Cartagena mediante modulación bfsk
No full textEl proyecto en desarrollo consiste en la construcción de un sistema de comunicaciones subacuático utilizando modulación BFSK. El objetivo principal del proyecto es establecer una comunicación eficiente y confiable en el medio subacuático, el cual presenta grandes desafíos debido a las características del medio, como la atenuación de la señal, la interferencia y el ruido ambiental. La comunicación subacuática es esencial en diversas aplicaciones, como el monitoreo del medio ambiente, la exploración y explotación de recursos naturales, la vigilancia y protección de costas, entre otros. El sistema desarrollado consiste en un transmisor y un receptor diseñados y construidos de manera artesanal. La modulación BFSK se utiliza debido a su capacidad para transmitir datos a una velocidad elevada y su capacidad de resistir la atenuación de la señal en el medio subacuático. El sistema se someterá a pruebas en un ambiente controlado, y se medirá su rendimiento en términos de tasa de errores de bit y tasa de éxito de la transmisión. De los resultados obtenidos se concluirá sí el sistema es funcional y puede transmitir datos a través del medio subacuático de manera eficiente y confiable. El proyecto tiene como objetivo contribuir al avance de la tecnología de comunicaciones subacuáticas, en un contexto donde la necesidad de soluciones de comunicación eficientes y confiables en el medio subacuático es cada vez mayor. La investigación en este campo tiene un gran potencial para impulsar el desarrollo de diversas aplicaciones, desde la exploración de recursos naturales hasta la protección del medio ambiente y la seguridad en el mar.Universidad Tecnologica de BolivarIngeniero ElectrónicoPregrad
reparación y reacción de los países del sur y norte global frente al COVID-19: un análisis comparado
No full textComparing the countries’ level of preparedness and response to the Covid-19 pandemic involves the assessment of human development, health, connectivity and death rate indicators. In this study, information published by the United Nations Development Program (UNDP) and the World Health Organization (WHO) was used to assess the performance of 148 countries classified as either of the Global South (Africa, Latin America and Asia-Oceania) or the Global North, describing how the unequal social and health conditions between regions are reflected in terms of contagion and death figures at year-end 2020. The HJ-Biplot multivariate technique was used to simultaneously represent both the countries and the indicators, providing a descriptive and exploratory analysis of how the countries’ level of preparedness to face the pandemic in terms of health and human development did not determine their success in reducing Covid-19 contagion and death rates, because success also depends on efficient and quick government action and reaction strategies. © 2022 Universidad Nacional de Colombia. All rights reserved.Medina-Hernández, E. J., Barco-Llerena, E., & Villalba-Acevedo, J. L. (2022). Preparação e reação dos países globais do sul e do norte contra a COVID-19: uma análise comparativa. HiSTOReLo. Revista de Historia Regional y Local, 14(30), 251-292
Metodología de selección de plataformas de producción offshore de hidrocarburos para el mar caribe
No full textEste trabajo desarrolla una metodología para la selección del sistema de producción más apropiado para un campo offshore ubicado en aguas profundas del Mar Caribe Colombiano, utilizando la técnica de decisión multicriterio AHP (Analytic Hierarchy Process), con una escala de valoración diferente a la original. En primer lugar, se hizo una revisión bibliográfica del estado del arte, a través de la indagación en fuentes primarias; seguidamente, se elaboró un resumen de los distintos métodos de decisión multicriterio. Posteriormente se incluyó en el documento, una exposición de las características de las plataformas de producción empleadas en aguas profundas y de los fundamentos y etapas del método AHP, así como una breve descripción de los principales criterios que se tienen en cuenta para la selección de plataformas offshore. En este punto, se propone una nueva escala de valoración y las modificaciones que se hacen necesarias en las ecuaciones originales. Se explican las etapas de la metodología planteada, y luego se presentan las comparaciones realizadas, implementando la técnica AHP, y por medio de la herramienta informática desarrollada, se logran los resultados buscados. Finalmente, se explican las conclusiones obtenidas a partir del proyecto realizado.Magister en Ingeniería Naval y OceánicaMaestrí
Thermal Energy Replacement Potential in a Slaughter Plant From Rumen Pellets
No full textIn this work, steam generation was studied using natural gas or rumen as energy sources in a slaughter plant that sacrifices 7500 cattle per month, with consumption 0.5749 kg/s of saturated steam at 624 kPa. For a slaughtered cow, 10.5 kg of rumen can be obtained after being dried outdoors; for its final disposal, the slaughter plant bears the costs of USD 7.2 per ton of rumen. In the study, exergy and exergoeconomic performances were compared by generating steam with a natural gas boiler with the steam generation with a rumen boiler. From this, combustion analysis, energy efficiency, exergy destruction, exergy efficiency, exergy destruction costs, and generating 1 kg of steam from the two boilers were evaluated. The study results showed that the generation of steam with rumen is less efficient than with natural gas since it presents the exergy destruction of 1175.9 kW and exergy efficiency of 26.83%. While the generation of steam with rumen boiler was obtained, with exergy destruction of 1419.9 kW and exergy efficiency of 23.29%. Exergy destruction cost and the cost of generating 1 kg of steam using rumen were /kg, respectively. Although the generation of steam with natural gas present the exergy destruction cost of 26285 /kg, this indicators are higher using natural gas as a fuel that with rumen pellets