Modelación geométrica del impulsor de una bomba centrífuga

El proyecto de grado Modelación Geométrica del Impulsor de una Bomba Centrífuga, busca desarrollar la construcción de un modelo digital del impulsor en acero inoxidable para una bomba marca Goulds, del modelo con diámetro, con los recursos y herramientas disponibles en la universidad EAFIT -- El diseño del modelo digital, se realizará utilizando herramientas de diseño asistidas por computador CAD (Computer Aided Design), y de análisis de la dinámica de fluidos CFD (Computational Fluid Dynamics), con el apoyo de técnicas de Ingeniería Inversa y herramientas de metrología, de tal forma que el modelo digital diseñado tenga las características de la pieza real -- El análisis de la forma geométrica de la pieza es el primer paso para su reconstrucción digital -- En esta etapa se busca obtener toda la información sobre las medidas geométricas más influyentes en el comportamiento del fluido, como son: la curvatura de los álabes, el diámetro del rodete, el diámetro de la entrada del fluido y la forma del contorno de las tapas superior e inferior -- Para garantizar la similitud geométrica entre el modelo digital y el modelo real del impulsor, el proyecto utilizará el método de evaluación establecido por la norma IEC 60193 de IEC (International Electrotechnical Commission

MINERÍA EN ECOSISTEMAS ESTRATÉGICOS Y PÉRDIDA DEL RECURSO HÍDRICO. CASO: PÁRAMO DE GUERRERO, COGUA CUNDINAMARCA

En Colombia se presenta una disyuntiva entre las necesidades económicas y el uso de los recursos naturales. Esta situación no es ajena al municipio de Cogua–Cundinamarca, debido a que se realiza actividad minera de carbón como medio de sustento económico, sin embargo, ella afecta el recurso hídrico del municipio.Las zonas en donde fueron otorgados los títulos mineros constituyen parte del complejo ecosistémico del Páramo de Guerrero, el cual tiene la función de producción y abastecimiento de agua, convirtiéndolo en un hecho que hace más aguda dicha disyuntiva y se entendería entonces que es la actividad económica a costa del recurso natural o el recurso natural a costa de la actividad económica, pero no las dos.Dicha problemática no es ajena a la población del municipio de Cogua, dado que a la vez que causa el deterioro por la actividad minera, es beneficiada por los servicios de abastecimiento hídrico que le provee el Páramo de Guerrero

Spanish normative data of the Strengths and Difficulties Questionnaire in a community-based sample of adolescents

Background/Objective: The Strengths and Difficulties Questionnaire self-report (SDQ-S) has been extensively used to assess mental health problems among children and adolescents. However, previous research has identified substantial age and country variation on its psychometric properties. The aim of this study was three-fold: i) to evaluate internal structure and measurement invariance of the Spanish version of the SDQ; ii) to analyze age and gender-specific effects on the SDQ subscales; and iii) to provide Spanish normative data for the entire age range of adolescence. Method: Data were derived from two representative samples of adolescents aged 14 to 19 years old, selected by stratified random cluster sampling years (N = 3378). Results: The reliability of the Total difficulties score was satisfactory, but some subscales showed lower levels of internal consistency. Confirmatory factor analysis supported the original five-factor model. Finally, results revealed that SDQ scores were influenced by the gender and the age of participants; thus, the normative banding scores and cut-off values were provided accordingly. Conclusions: This study validates the Spanish SDQ-S for the entire age range of adolescence. However, more cross-country and cross-age research is needed to better understand the inconsistent findings on SDQ reliability

Thermodynamic and kinetic study of the recovery of tungsten and cobalt from tool waste

In the present research work, the recovery of tungsten and cobalt from waste coming from tungsten carbide-cobalt (WC-Co) tools, which are widely used in the metalworking industry, was analyzed. The WC-Co waste was characterized by X-ray diffraction and scanning electron microscopy with microanalysis (SEM/EDS). The process started with the oxidation of the waste to obtain a mixture of oxides (WO3 and CoWO4). The ΔH and ΔG were calculated both for the oxidation and reduction processes. Thermodynamic and non-isothermal kinetic analyses were carried out to obtain a stability diagram where theoretical and experimental data are defined by transformation lines as a function of temperature; in addition, the apparent activation energy was determined. By a hydrogen reduction process, high-purity tungsten and cobalt in metallic form were obtained

Spanish normative data of the Strengths and Difficulties Questionnaire in a community-based sample of adolescents

Background/Objective: The Strengths and Difficulties Questionnaire self-report (SDQ-S) has been extensively used to assess mental health problems among children and adolescents. However, previous research has identified substantial age and country variation on its psychometric properties. The aim of this study was three-fold: i) to evaluate internal structure and measurement invariance of the Spanish version of the SDQ; ii) to analyze age and gender-specific effects on the SDQ subscales; and iii) to provide Spanish normative data for the entire age range of adolescence. Method: Data were derived from two representative samples of adolescents aged 14 to 19 years old, selected by stratified random cluster sampling years (N = 3378). Results: The reliability of the Total difficulties score was satisfactory, but some subscales showed lower levels of internal consistency. Confirmatory factor analysis supported the original five-factor model. Finally, results revealed that SDQ scores were influenced by the gender and the age of participants; thus, the normative banding scores and cut-off values were provided accordingly. Conclusions: This study validates the Spanish SDQ-S for the entire age range of adolescence. However, more cross-country and cross-age research is needed to better understand the inconsistent findings on SDQ reliability

Low prevalence of vancomycin-resistant enterococci in clinical samples from hospitalized patients of the Canary Islands, Spain

Over the last decade vancomycin-resistant enterococci (VRE) have emerged as nosocomial pathogens. The aim of this study was to determine the prevalence of VRE in clinical samples from hospitalized patients in the Canary Islands. From April to November 2000, 437 enterococci were isolated from patients hospitalized at the four main health care centers in those islands. Identification to the species level was performed with the GPS-TA (Vitek 1) or the Wider I system. A PCR assay was used to determine the genotype of glycopeptide resistance (vanA, vanB, vanC1, and vanC2/C3 genes). Only three (0.7%) VRE were detected: one vanA Enterococcus faecalis, and two vanC1 Enterococcus gallinarum. To our knowledge, this is the first VRE study carried out in the Canary Islands hospitals, and the results showed a low prevalence of VRE

Gestión empresarial de las pequeñas y medianas empresas para el crecimiento económico

El avance en las pequeñas y medianas empresas (pymes), las cuales hoy en día en el mercado global, tienen como objetivo principal el crecimiento económico, en caso de que estas empresas quieran mantenerse, avanzar o expandirse en un entorno mundial y dinámico, deben proponer estrategias las cuales les faciliten alcanzar su desarrollo empresarial. En el siguiente artículo se pretende analizar como la gestión empresarial representa ser un aspecto fundamental para el crecimiento económico, potenciando el desempeño y desarrollo de las empresas ya que la gestión empresarial es la que determina el planteamiento para el crecimiento de la empresa, para llevar a cabo los objetivos y así aportar con la supervivencia y crecimiento de la empresa

Corneal endothelium assessment in specular microscopy images with Fuchs’ dystrophy via deep regression of signed distance maps

Specular microscopy assessment of the human corneal endothelium (CE) in Fuchs’ dystrophy is challenging due to the presence of dark image regions called guttae. This paper proposes a UNet-based segmentation approach that requires minimal post-processing and achieves reliable CE morphometric assessment and guttae identification across all degrees of Fuchs’ dystrophy. We cast the segmentation problem as a regression task of the cell and gutta signed distance maps instead of a pixel-level classification task as typically done with UNets. Compared to the conventional UNet classification approach, the distance-map regression approach converges faster in clinically relevant parameters. It also produces morphometric parameters that agree with the manually-segmented ground-truth data, namely the average cell density difference of -41.9 cells/mm2 (95% confidence interval (CI) [-306.2, 222.5]) and the average difference of mean cell area of 14.8 µm 2 (95% CI [-41.9, 71.5]). These results suggest a promising alternative for CE assessment.This work has been partly funded by Ministerio de Ciencia, Tecnología e Innovación, Colombia, Project 124489786239 (Contract 763-2021), Universidad Tecnológica de Bolívar (UTB) Project CI2021P02, and Agencia Estatal de Investigación del Gobierno de España (PID2020-114582RB-I00/ AEI / 10.13039/501100011033). J. Sierra thanks UTB for a post-graduate scholarship.Peer ReviewedPostprint (published version

Caracterización del remodelado del colágeno asociado a la edad en el ventrículo izquierdo humano de donantes vivos y sus implicaciones en la generación de arritmias

La edad es un factor de riesgo arrítmico que, en especies animales, está asociado a la remodelación del colágeno. En este trabajo caracterizamos la dinámica tisular del colágeno asociada a la edad en el ventrículo izquierdo humano y utilizamos estos resultados para simular su efecto sobre la generación de arritmias ventriculares