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ilustraciones, fotografías a color En esta investigación se evaluaron las propiedades de permeabilidad al aire y al agua, la resistencia a la penetración de cloruros, impedancia eléctrica, porosidad, densidad, resistencia a la compresión y módulo de elasticidad de cinco mezclas de concreto adicionadas con arcilla calcinada y caliza en diferentes proporciones (M01) a (M05) y una mezcla de referencia sin ninguna adición (MR). Todas las mezclas fueron diseñadas por el Ingeniero Luis Felipe Salazar (Salazar Mayorga, 2023), integrante del grupo de investigación y análisis dirigido por el Ingeniero Juan Manuel Lizarazo Marriaga, como base para la realización de una serie de investigaciones sobre los cementos adicionados con arcilla calcinada y caliza. Todas las mezclas tienen la misma relación agua /cementante igual a 0.50 y la arcilla calcinada utilizada es de baja gradación, con un contenido de caolinita igual al 40%. El cemento utilizado como referencia es de marca Alión de altas resistencias tempranas (ART) por ser un cemento con un mínimo de adiciones y muy cercano a lo que se considera un cemento pórtland. Las probetas fueron curadas y ensayadas a edades superiores a 90 días en el laboratorio de Ingeniería de la Universidad Nacional de Colombia, sede Bogotá. El ensayo de Salt Ponding Test - SPT; se realizó según las normas NT-443 para el acondicionamiento de probetas y NT-492 para evaluación de la profundidad de penetración. Las probetas permanecieron sumergidas en solución salina durante 148 días adicionales a los 90 días de curado. Al analizar los resultados correspondientes a las propiedades mecánicas, se encontró que la resistencia a la compresión en las mezclas adicionadas hasta con un 45% de arcilla calcinada más caliza (M01 a M04) es similar a la de la mezcla de referencia (MR). Para un porcentaje de sustitución del cemento del 50% (M05) la resistencia a la compresión disminuyó en un 17%. El módulo de elasticidad en las mezclas adicionadas M01 a M04 tiene un valor similar al de la mezcla de referencia MR. Para la mezcla M05 con un 50% de sustitución del cemento, el valor del módulo de elasticidad disminuyó un 15% respecto al de la mezcla de referencia MR. La densidad de todas las mezclas es muy similar y no se encontró variación apreciable. La porosidad de las mezclas adicionadas fue menor que la de la mezcla de referencia a excepción de la mezcla M01 que presentó un valor ligeramente mayor. En cuanto a las propiedades relacionadas a la durabilidad se evaluaron la permeabilidad al aire y al agua, la resistencia a difusión y migración de cloruros y la impedancia eléctrica. La totalidad de las mezclas presentaron baja permeabilidad al aire. Se evidenció que la adición de arcillas calcinadas y caliza, tal como se esperaba, efectivamente disminuye la permeabilidad al aire debido a un refinamiento en la estructura de poros del concreto. El contenido óptimo de adiciones corresponde a la mezcla M02 con un 20% de arcilla calcinada y 10% de caliza. La permeabilidad al agua de todas las mezclas se evaluó como baja. No se pudo establecer una relación cuantitativa confiable entre las mezclas debido a deficiencias en la calidad de la pintura epóxica utilizada que distorsionó los resultados al permitir que el flujo de agua no fuera unidireccional. No hay relación cuantitativa alguna entre la permeabilidad al aire y al agua debido esencialmente a la naturaleza y comportamiento de los fluidos. La resistencia a la penetración de cloruros en todas las muestras adicionadas fue menor que la de la mezcla de referencia. De acuerdo con el ensayo Nordtest Build- 492 (NT Build-492) el porcentaje óptimo de sustitución de cemento es del 60% correspondiente a la mezcla M03. El ensayo de estancamiento de sal SPT dio como resultado un contenido óptimo de adiciones igual al 45% del contenido de Clinker, correspondiente a la mezcla M02, pero con muy poca diferencia con las muestras más adicionadas M03, M04 y M05. El ensayo de impedancia eléctrica dio como resultado que todas las muestras adicionadas tienen una mayor impedancia que la mezcla de referencia. Esto se debe al incremento de la alcalinidad de la solución de poros por causa de la arcilla calcinada. El comportamiento de las mezclas es consistente con lo encontrado en los ensayos de migración y difusión de cloruros Como conclusión de la investigación se encontró que los concretos adicionados con arcillas calcinadas y caliza mejoran las propiedades mecánicas y de durabilidad con porcentajes de sustitución del cemento desde un 40% hasta un 60% (factor Clinker 60% a 40%). El alto nivel de sustitución debe verse con mucho cuidado puesto que al reducir el porcentaje de cemento pórtland también se reduce la disponibilidad de material carbonatable y la durabilidad se ve comprometida por temas de corrosión. (Texto tomado de la fuente) In this research, the properties of permeability to air and water, resistance to chloride penetration, electrical impedance, porosity, density, compressive strength, and elasticity modulus of five concrete mixtures blended with different proportions of calcined clay and limestone were evaluated (M01) to (M05), and a reference mixture without any addition (MR). Engineer Luis Felipe Salazar designed all the mixtures (Salazar Mayorga, 2023), a member of the research and analysis group led by Engineer Juan Manuel Lizarazo Marriaga, as the basis for carrying out a series of investigations on cements blended with calcined clay and limestone. All the mixes have the same water/cement ratio equal to 0.50. The calcined clay used is a low-grade clay, with a kaolinite content equal to 40%. The cement used as a reference is Alión brand of high early resistance (ART) because it is a cement with a minimum of additions and close to what is considered a pórtland cement. The specimens were cured and tested at ages greater than 90 days in the Engineering laboratory of the National University of Colombia, Bogotá headquarters. The Salt Ponding Test - SPT test; It was carried out according to the standards NT-443 for the conditioning of test tubes and NT-492 for evaluation of the depth of penetration. The specimens remained submerged in saline solution for an additional 148 days after 90 days of curing. When analyzing the results corresponding to the mechanical properties, it was found that the compressive strength in the mixtures blended with up to 45% of calcined clay plus limestone (M01 to M04) is like that of the reference mixture (MR). For a 50% substitution of cement (M05), the compressive strength decreased by 17%. The modulus of elasticity in the added mixtures M01 to M04 has a value like that of the reference mixture MR. For the mix M05 with 50% substitution of the cement, the value of the modulus of elasticity decreased by 15% compared to that of the reference mix MR. The density of all the mixtures is similar and no appreciable variation was found. The porosity of the blended mixtures was lower than that of the reference mixture MR, except for the M01 mixture, which presented a slightly higher value. Regarding the properties related to durability, the permeability to air and water, the resistance to diffusion and migration of chlorides and the electrical impedance were evaluated. All the mixtures had low air permeability. It was evidenced that the addition of calcined clays and limestone, as expected, effectively decrease the air permeability due to a refinement in the pore structure of the concrete. The optimal content of additions corresponds to the mixture M02 with 20% of calcined clay and 10% of limestone. The water permeability of all blends was evaluated as low. A reliable quantitative relationship between the mixtures could not be established due to deficiencies in the quality of the epoxy paint used, which distorted the results by allowing the water flow to not be unidirectional. There is no quantitative relationship between air and water permeability due to the nature and behavior of fluids. The resistance to chloride penetration in all the blended mixtures was lower than that of the reference mixture. According to the Nordtest Build 492 (NT Build-492) test, the optimum cement substitution percentage is 60% (Clinker factor 40%) corresponding to the M03 mixture. The SPT test resulted in an optimal content of additions equal to 45% of the Clinker content, corresponding to the M02 mix, but with very little difference with the most added samples M03, M04 and M05. The electrical impedance test resulted in all the blended mixtures having a higher electrical impedance than the reference mixture. This is due to the increase in the alkalinity of the pore solution due to the calcined clay. The behavior of the mixtures is consistent with what was found in the chloride migration and diffusion tests. As a conclusion of the investigation, it is found that the concretes blended with calcined clays and limestone improve their mechanical and durability properties with substitution percentages of cement from 40% to 60% (Clinker factor 60% to 40%). This elevated level of substitution must be viewed with great care since reducing the percentage of pórtland cement also reduces the availability of carbonated material and then durability is compromised by corrosion issues. Maestría Magíster en Ingeniería - Estructuras Materiales para construcción

Manufacturing methods of CPC collectors, regardless the application, have not undergone significant modifications in recent years; the main manufacturing methods are hydraulic press stamping and some other machining methods, which generate errors in geometric curvature and damage to the high-reflectivity film coating, reducing the overall optical efficiency of the CPC. In this work, we propose a method for the fabrication of cylindrical CPCs (widely used in water-heating, disinfection, and wastewater treatment applications), which comprises the use of a 3D printed mold complemented with a structural styrofoam molding. The proposed method presents the advantage of improving the quality of the CPC profile with less damage on the surface of the high reflectivity coating and with a reduction in the quantity of deformations because of its machining processes. To evaluate the effectiveness of the presented method, an experimental-simulation test was carried out based on a photogrammetric technique combined with a Ray tracing Monte Carlo method. The test procedure compared the CPC manufactured with the proposed method (called 3DMCPC) versus one manufactured by a conventional machining technique (referred as CM-CPC). The results obtained show a geometrical mean error value of 1.2 mm for the 3DM-CPC compared to 3.19 mm for the CM-CPC. Optical assessment by ray tracing showed a relative efficiency of 95% for the 3DM-CPC versus 82% of the CM-CPC, both of them compared to the theoretical ideal geometry of a 2D-1 Sun CPC. The benefit could be estimated in a simulation to be 9.4% in the annual performance of a 1000 L CPC thermal energy solar plant.

ilustraciones, gráficas El desarrollo y crecimiento de la Fisioterapia a nivel mundial y nacional le implicó a esta profesión incursionar en ámbitos menos clínicos y tradicionales, a los que históricamente se le ha vinculado, entre ellos el área deportiva. Lo anterior se justifica, entre otros aspectos, por la creciente demanda en estas áreas de profesionales del movimiento altamente especializados. Este rápido crecimiento llevó a los profesionales a especializarse y a continuar sus procesos de formación de manera constante y en nuevas áreas de ejercicio profesional. En este contexto, la Fisioterapia como profesión liberal y autónoma, que realiza sus procesos de autorregulación, tiene la necesidad constante de conocer la situación profesional y laboral de su gremio con el fin de mejorar de manera constante. En Colombia se han realizado estudios de seguimiento profesional de una manera general para los fisioterapeutas y en áreas que no son el campo específico del deporte de alto rendimiento, como por ejemplo en el área de rehabilitación cardio pulmonar. Esto significa que hoy existe una falta de conocimiento de la situación profesional y laboral en el campo específico de estos profesionales altamente especializados. Lo que se convierte en una limitante para visibilizar necesidades específicas y plantear alternativas de solución para las mismas. Se realizó un estudio de naturaleza descriptiva, observacional de corte trasversal, cuya finalidad fue describir y analizar las condiciones laborales y profesionales de los fisioterapeutas que ejercen sus labores en el deporte de alto rendimiento a nivel nacional. Esto a través de una encuesta realizada por medio electrónico y contestada por fisioterapeutas que ejercen sus labores en deporte de alto rendimiento en entidades públicas o privadas. El instrumento propuesto constó de 6 dominios: información general demográfica, formación profesional, condiciones laborales, actividades realizadas, competencias profesionales e información gremial. El análisis y los resultados permitieron: conocer la realidad del gremio de los fisioterapeutas del deporte de alto rendimiento en Colombia; compararlos con otras áreas de desempeño profesional; y aportar a las discusiones y procesos de crecimiento profesional de los profesionales, universidades, entidades gremiales y gubernamentales. Dentro de los hallazgos más importantes se encuentran: la composición demográfica de la población, el nivel educativo, las condiciones laborales como nivel salarial e independencia profesional. Igualmente se lograron identificar necesidades y expectativas de formación profesional, con énfasis en las competencias profesionales específicas del campo, del fisioterapeuta que ejerce en el deporte de alto rendimiento en Colombia. (Texto tomado de la fuente) The development and growth of physiotherapy at a global and national level has led this profession to venture into less clinical and traditional areas in which it has been related, including the sports area. This is justified, among other aspects, by the growing demand in these areas for highly specialized movement professionals. This rapid growth has led professionals to specialize and continue their training processes constantly and in new areas of professional practice. Physiotherapy as a liberal and autonomous profession that carries out its self-regulation processes has the constant need to know the professional and employment situation of its union in order to constantly improve. In Colombia, professional follow-up studies have been carried out in a general way for physiotherapists in areas other than the specific field of high-performance sports, especially in the field of cardiopulmonary rehabilitation. This lack of knowledge of the professional and labor situation in the specific field of these highly specialized professionals is a limitation to make specific needs visible and propose alternative solutions for them. A descriptive, observational, cross-sectional study was carried out, its purpose was to describe and analyze the working and professional conditions of physiotherapists who work in high-performance sports at the national level. This through a survey carried out electronically and answered by physiotherapists who work in public or private entities of high-performance sports in Colombia. The proposed instrument consisted of six domains (general demographic information, professional training, working conditions, activities carried out, professional skills and union information). The analysis and results allowed: to know the reality of the union of high-performance sports physiotherapists in Colombia; compare them with other areas of professional performance; and contribute to the discussions and processes of professional growth of professionals, universities, union and government entities. Maestría Magíster en Fisioterapia del Deporte y la Actividad Física

The design and location of solar energy technologies are based chiefly on the availability of solar resource. Specialized measurement equipment and solar resource assessment techniques are mandatory in order to identify appropriate locations for deploying solar systems while minimizing risk and increasing the return rate of the site. These needs have given the scientific community a motivation to design highly reliable and cost-competitive sensors. This work presents a novel methodology to estimate solar irradiance components using a low-cost sky-imager system. Captured images are processed to correct the spherical aberration of the dome and to achieve a pixel-radiance model, allowing each pixel of the image to be considered as an individual source of irradiation. The performance of the proposed model is analyzed and compared in four different weather scenarios against a secondary standard solarimetric station, obtaining a normalized mean bias error for direct normal irradiance, global horizontal irradiance and diffuse horizontal irradiance of 4.53%, −6.55% and 19.62% for a sunny day, 0.79%, −6.13% and 7.00% for a partially sunny day, 1.96%, −6.58% and −0.73% for a partially cloudy day, 100%, −10.48% and −0.65% for a cloudy day, respectively. According to the experimental results, the system stands out for its performance, easy setup, low-cost components and a robust estimation in all possible weather scenarios.

Considering of multiples research of genetic in cats, the objective of this study was to compare the genetic diversity of the domestic cat population at different spatial and temporal scales. According to the administrative division of the city of Cali, 8 colonies (localities) were chosen, which together form 5 subpopulations within the city for sampling. The phenotype from each individual?s coat was recognized for the subsequent calculation of allele frequencies, Hardy-Weinberg (HW) equilibrium, genetic structure, and correlated genetic diversity and structure with antiquity in each neighborhood. The non-agouti allele obtained the highest frequencies, and the white allele had the lowest frequencies in all colonies and subpopulations; the manx allele was also reported. HW equilibrium was found in the orange locus, except for the Salomia, Sena and Santa Barbara colonies of the NW subpopulation. A significant association was found between the diversity of the tabby locus and antiquity and the differentiation of the colonies (FCT) with antiquity of colonies. In conclusion, domestic cats in the city of Cali behave as a single population, with incipient genetic microstructure phenomena, which are part of the natural dynamics of the population in their interaction with the urban environment.

It is well known that concentrating solar power and concentrating photovoltaic technologies require high accuracy and high precision solar tracking systems in order to achieve greater energy conversion efficiency. The required tracking precision depends primarily on the acceptance angle of the system, which is generally tenths of a degree. Control algorithms applied to active solar tracking systems command and manipulate the electrical signals to the actuators, usually electric motors, with the goal of achieving accurate and precise solar tracking. In addition, a solar tracking algorithms system must provide robustness against disturbances, and it should operate with minimum energy consumption. In this work, a systematic review of the control algorithms implemented in active solar tracking systems is presented. These algorithms are classified according to three solar tracking control strategies: open-loop, closed-loop and combined open- and closed-loop schemes herein called hybrid-loop. Their working principles as well as the main advantages and disadvantages of each strategy are analyzed. It is concluded that the most widely used solar tracking control strategy is closed-loop, representing 54.39% of all the publications consulted. On–off, fuzzy logic, proportional-integral-derivative and proportional-integral are the control algorithms most applied in active solar tracking systems, representing 57.02%, 10.53%, 6.14% and 4.39%, respectively.