Optimal Integration of Distributed Generators into DC Microgrids Using a Hybrid Methodology: Genetic and Vortex Search Algorithms

This paper addresses the problem of optimal location and sizing of distributed generators (DGs) in direct current (DC) grids. To solve it, we propose an optimization approach with an objective function that aims to reduce power losses due to energy transport, while considering all the constraints that represent DC grids in a distributed generation environment. For the mathematical formulation of the problem, we used a mixed-integer nonlinear programming (MINLP) model, which allowed us to evaluate the impact of all possible configurations (i.e., location and size of DGs in the DC network) on the objective function and the constraints. The solution method proposed here is a master–slave strategy that implements a hybrid solution methodology that combines a genetic algorithm (GA) and the vortex search algorithm (VSA). The GA is in charge of solving the location problem in the master stage, and the VSA is responsible for sizing the DGs in the slave stage. To evaluate the effectiveness and robustness of the proposed GA/VSA methodology, we employed two test systems (i.e., 21 and 69 buses) considering a maximum penetration of distributed generation equal to 40% of the power generated by the slack buses. Furthermore, we also implemented nine other hybrid methodologies based on metaheuristic techniques (proposed in the literature for solving the problem addressed here) to make comparisons. All the solution methods used and proposed in this paper are based on sequential programming to avoid the need for specialized software and thus reduce the complexity and cost of the solutions. The effectiveness of the proposed solution was evaluated in two scenarios: (1) peak power demand and (2) variation in power generation and demand associated with photovoltaic generation and user demand in Medellín, Colombia. The results demonstrate that the GA/VSA methodology achieved the best results in terms of solution quality and processing times in all the test scenarios proposed in this study. © 2022, King Fahd University of Petroleum & Minerals

Optimal Power Dispatch in Direct Current Networks to Reduce Energy Production Costs and CO 2 Emissions Using the Antlion Optimization Algorithm

In this study, we present a master–slave methodology to solve the problem of optimal power dispatch in a direct current (DC) microgrid. In the master stage, the Antlion Optimization (ALO) method solves the problem of power dispatch by the Distributed Generators (DGs); in the slave stage, a numerical method based on successive approximations (SA) evaluates the load flows required by the potential solutions proposed by the ALO technique. The objective functions in this paper are the minimization of energy production costs and the reduction of CO 2 emissions produced by the diesel generators in the microgrid. To favor energy efficiency and have a lower negative impact on the environment, the DC microgrids under study here include three DGs (one diesel generator and two generators based on renewable energy sources, i.e., solar energy and wind power) and a slack bus connected to a public electrical grid. The effectiveness of the proposed ALO–SA methodology was tested in the 21- and 69-bus test systems. We used three other optimization techniques to compare methods in the master stage: particle swarm optimization, continuous genetic algorithm, and black hole optimization. Additionally, we combined SA with every method to solve the load flow problem in the slave stage. The results show that, among the methods analyzed in this study, the proposed ALO–AS methodology achieves the best performance in terms of lower energy production costs, less CO 2 emissions, and shorter computational processing times. All the simulations were performed in MATLAB. © 2021, King Fahd University of Petroleum & Minerals.Ocampo-Toro, J. A., Garzon-Rivera, O. D., Grisales-Noreña, L. F., Montoya-Giraldo, O. D., & Gil-González, W. (2021). Optimal Power Dispatch in Direct Current Networks to Reduce Energy Production Costs and CO 2 Emissions Using the Antlion Optimization Algorithm. Arabian Journal for Science and Engineering, 46(10), 9995-10006

16. DISEÑO DE UN MODELO DE GESTIÓN DEL CONOCIMIENTO QUE PERMITA LA PERMANENCIA DE LOS ESTUDIANTES DE EDUCACIÓN SUPERIOR VIRTUAL: CASO ECACEN ZONA OCCIDENTE

En los últimos años, la educación en todas sus modalidades se ha enfrentado a diferentes situaciones de tipo político, económico, social y cultural; las cuales es necesario investigar para conocerlos, afrontarlos y diseñar planes y modelos que permitan a los diferentes actores involucrados en los procesos formativos y encontrar soluciones. Es así como el objetivo de esta investigación es diseñar un modelo de Gestión del Conocimiento que permita la retención y permanencia de los estudiantes de educación superior virtual de la Escuela de Ciencias Administrativas, Contables, Económicas y de Negocios (ECACEN) en la Zona Occidente (ZOCC) de la Universidad Nacional Abierta y a Distancia (UNAD), a través de la identificación de los factores que propician la deserción de los estudiantes con el fin de promover la permanencia, determinando su eficacia en la prevención de la deserción y la retención de la población estudiantil. El diseño metodológico de esta investigación es del tipo descriptivo de corte transversal, que permitirá obtener información para la construcción de un modelo de gestión del conocimiento, que beneficie a los estudiantes en su proceso formativo, a la sociedad en su desarrollo económico y social, y la universidad en su razón de ser

Analisis de las respuestas moleculares profundas alcanzadas por las multiples secuencias de tratamientos con ITKS en LMC. Estudio de largo seguimiento del registro español de LMC

Poster [PC-231] Introducción: Cinco inhibidores de tirosina cinasa (ITKs) están disponibles para el tratamiento de pacientes con leucemia mieloide crónica en fase crónica (LMC-FC). Analizamos las diferentes secuencias de ITKs utilizadas como terapia para la LMC-FC en un análisis a largo plazo en vida real. Métodos: En un análisis retrospectivo de cohortes, se incluyeron pacientes con LMC-FC tratados en la práctica clínica con diferentes ITKs en el Registro Español de LMC (RELMC) (17 hospitales de todo el país) entre 2000 y 2014. El objetivo principal del estudio fue describir la secuencia del tratamiento con ITKs en la práctica de la vida real y la última respuesta molecular profunda (DMR) (MR4, MR4.5 o transcrito indetectable) para cada esquema. Resultados: Nuestro análisis incluyó 862 pacientes con LMC en 1º FC tratados con ITKs en 1ª línea o después de interferón alfa. Datos demográficos demográficos: 517 H, 345 M, mediana de edad: 52 años (14-94a). Distribución del Índice Sokal (bajo 49% Inter 38% Alto 13%), Índice EURO (bajo 50% Inter 45% Alto 5%), Índice EUTOS (bajo 93% Alto 7%), Índice LT-EUTOS (bajo 68 % Inter 25% Alto 7%). Esquemas de tratamiento: la Tabla 1 resume todos los esquemas utilizados y la última respuesta molecular. Los pacientes se dividieron en 4 grupos según el tratamiento con ITKs. Grupo 1: solo tratados con Imatinib 394 p (45, 7%) Grupo 2: Imatinib y luego 2ºGITKs debido a intolerancia o fallo 170 p (19, 7%) (12 esquemas de tratamiento secuenciales diferentes con ITKs) Grupo 3: 2ºGITKs en 1ª línea 91 p (13 esquemas secuenciales) (10, 5%) Grupo 4: Interferón alfa y luego ITKs 207 p (24%) (9 esquemas secuenciales). La Figura 1 resume la evolución de diferentes tratamientos alrededor de los 14 años. Última respuesta molecular profunda: con una mediana de seguimiento de 82 meses (1-351 m) desde el diagnóstico, 77 m (1-311 m) desde el primer tratamiento y 70 m (1-191 m) desde el primer tratamiento con ITK. Las tasas de respuesta molecular profunda para cada grupo fueron (G1: DMR 65% MMR 13% No MMR 15%, G2: DMR 46% MMR 24% No MMR 17%, G3: DMR 62% MMR 13% No MMR 12%, G4: DMR 53% MMR 17% No MMR 18%). Supervivencia a largo plazo (SLP o SG): no se encontraron diferencias estadísticas entre los grupos de tratamiento, ya sea desde el diagnóstico, el primer tratamiento o el primer ITK. Alcanzar una respuesta profunda garantiza mejores resultados. Variables predictivas de respuesta: los índices SOKAL, EUTOS, EURO y LT-EUTOS continúan siendo útiles para predecir el resultado a largo plazo. Conclusiones: En el contexto de un registro multicéntrico basado en hospitales, el tratamiento con ITKs es muy variable, con un gran número de secuencias diferentes de ITKs. Con una mediana de seguimiento de 7 años la tasa de respuesta molecular profunda es aproximadamente del 60% en pacientes tratados con imatinib y que no necesitan cambio de ITKs, y en aquellos tratados en 1º línea con 2ºGITKs(a pesar de su corto seguimiento), pero parece menor en pacientes tratados con imatinib que necesitan cambiar a 2ºGITKs. Los resultados de supervivencia fueron similares para todos los grupos

Bronchoscopist's perception of the quality of the single-use bronchoscope (Ambu aScope4™) in selected bronchoscopies: a multicenter study in 21 Spanish pulmonology services

Background: The disposable bronchoscope is an excellent alternative to face the problem of SARS-CoV-2 and other cross infections, but the bronchoscopist's perception of its quality has not been evaluated. Methods: To evaluate the quality of the Ambu-aScope4 disposable bronchoscope, we carried out a cross-sectional study in 21 Spanish pulmonology services. We use a standardized questionnaire completed by the bronchoscopists at the end of each bronchoscopy. The variables were described with absolute and relative frequencies, measures of central tendency and dispersion depending on their nature. The existence of learning curves was evaluated by CUSUM analysis. Results: The most frequent indications in 300 included bronchoscopies was bronchial aspiration in 69.3% and the median duration of these was 9.1 min. The route of entry was nasal in 47.2% and oral in 34.1%. The average score for ease of use, image, and aspiration quality was 80/100. All the planned techniques were performed in 94.9% and the bronchoscopist was satisfied in 96.6% of the bronchoscopies. They highlighted the portability and immediacy of the aScope4TM to start the procedure in 99.3%, the possibility of taking and storing images in 99.3%. The CUSUM analysis showed average scores > 70/100 from the first procedure and from the 9th procedure more than 80% of the scores exceeded the 80/100 score. Conclusions: The aScope4™ scored well for ease of use, imaging, and aspiration. We found a learning curve with excellent scores from the 9th procedure. Bronchoscopists highlighted its portability, immediacy of use and the possibility of taking and storing images

Mapping density, diversity and species-richness of the Amazon tree flora

Using 2.046 botanically-inventoried tree plots across the largest tropical forest on Earth, we mapped tree species-diversity and tree species-richness at 0.1-degree resolution, and investigated drivers for diversity and richness. Using only location, stratified by forest type, as predictor, our spatial model, to the best of our knowledge, provides the most accurate map of tree diversity in Amazonia to date, explaining approximately 70% of the tree diversity and species-richness. Large soil-forest combinations determine a significant percentage of the variation in tree species-richness and tree alpha-diversity in Amazonian forest-plots. We suggest that the size and fragmentation of these systems drive their large-scale diversity patterns and hence local diversity. A model not using location but cumulative water deficit, tree density, and temperature seasonality explains 47% of the tree species-richness in the terra-firme forest in Amazonia. Over large areas across Amazonia, residuals of this relationship are small and poorly spatially structured, suggesting that much of the residual variation may be local. The Guyana Shield area has consistently negative residuals, showing that this area has lower tree species-richness than expected by our models. We provide extensive plot meta-data, including tree density, tree alpha-diversity and tree species-richness results and gridded maps at 0.1-degree resolution

Consistent patterns of common species across tropical tree communities

Trees structure the Earth’s most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations1,2,3,4,5,6 in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth’s 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories7, we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world’s most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees