Envíos recientes

B. Investigación

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Implementación de un sistema hidropónico para la producción de Oryza sativa como forraje con potencial en alimentación animal

Eslava Pedraza, Alix Amanda | 2022-11-09

Una de las alternativas para la optimización de los sistemas pecuarios, es la implementación de tecnologías como la producción de ensilajes, henos y forraje verde hidropónico (FVH). Este estudio buscó implementar un sistema hidropónico para la producción de FVH de arroz (O. Sativa), gramínea poco convencional para alimentación animal, esto en condiciones de baja temperatura y alta humedad, variando entre 17 °C y 24 °C y 60 % y 80 %, respectivamente. La evaluación agronómica tuvo una duración de 38 días para la cosecha principal (CP) y 21 días para la soca (CS). Las semillas utilizadas fueron regadas manualmente, aplicándoseles fertilizantes desde el día 21 postsiembra; además, fueron seleccionadas, desinfectadas y sometidas a pregerminación. Se realizó un análisis descriptivo cuantitativo, se utilizaron modelos de regresión lineal. Las variables evaluadas en CP y CS fueron: altura total (cm), altura del tallo (cm), longitud de la hoja principal (cm), relación hoja/tallo y cantidad de hojas/plántula. Se observó un constante crecimiento de las plántulas hasta el día 26 postsiembra; luego, se halló que el crecimiento en altura fue mínimo. Respecto a la CS, se encontró rebrote en algunas áreas dispersas del tapete radicular, alcanzando una altura menor a la registrada en la CP, donde se evidenció muerte prematura de las plántulas. Se pudo concluir, finalmente, que en las condiciones ambientales del experimento el rendimiento en biomasa y altura es bajo; sin embargo, la composición nutricional de O. sativa indica que la implementación de la hidroponía permite proponer la producción de FVH de esta gramínea como una alternativa promisoria en alimentación animal.

Antimicrobial evaluation of silver nanoparticles using extracts of Crescentia cujete L.

Sánchez, Manuel Alejandro | 2023-03-26

New natural reducing agents with a lower negative impact on the environment and with a high antimicrobial potential are required for the process of obtaining silver nanoparticles through the chemical reduction method. The use of plant extracts can be a fast track in the formation of nanoparticles. In this case, organic compounds such as terpenes, flavonoids, enzymes, proteins, and cofactors present in plants act as reducing agents for nanomaterials. This research evaluated the antimicrobial property of silver nanoparticles from extracts of Crescentia cujete L. The presence of quercetin (flavonoid) was determined by high-performance liquid chromatography (HPLC); the production of silver nanoparticles (AgNPs) was established by green synthesis; the size and morphology of the nanomaterials were evaluated by scanning electron microscope (SEM). The antimicrobial capacity was studied by two analysis methods: modified culture medium and surface seeding. The presence of quercetin (26.55 mg L-1) in the crude extract of Crescentia cujete L., identified by HPLC, was evidenced. Nanoparticle formation was spherical, with an average size of 250 ± 3 and 460 ± 6 nm. Microbiological cultures with treatment showed 94% microbial inhibition. It was concluded that the Crescentia cujete L., leaves shoed an acceptable concentration of quercetin to be used as a useful adjuvant to enhance the reduction of NPs synthesis. The nanoparticles produced by green synthesis proved to have a positive effect to combat pathogenic microorganisms

Effects of Environmental Conditions on Photovoltaic Generation System Performance with Polycrystalline Panels

Mejía Ruiz, Saúl | 2021-10-31

Photovoltaic solar energy is the third most widely used renewable source worldwide, after hydroelectric and wind energy, and this energy source requires experimental and theoretical development in specific topics such as the effect of environmental conditions on energy performance. Thus, this study's main objective was to determine the influence that meteorological conditions have on the performance of solar photovoltaic systems, based on measurements from a measurement station installed in the city of Barranquilla-Colombia, to determine the factors that significantly affect the system’s energy efficiency deviation. The experimental results show a dependence of the solar panel energy performance on some weather conditions, which is an uncontrolled phenomenon such as the ambient temperature and the atmosphere's humidity. Also, solar panel temperature and irradiance were the parameters with greater importance in the systems power generation. Also, the panel temperature must be controlled to obtain the desired response, because the panel temperature is inversely proportional to the voltage and directly proportional to the current. However, the negative effect of increased panel temperature in sunny climates is compensated by increased solar hours, so the summer system has less instantaneous efficiency, but it has higher solar output throughout the day. Therefore, solar energy production study should be related to total daily production.

Hydraulic optimization of the physical parameters of a drinking water distribution system

Bonilla Granados, Carlos Alexis | 2021-09-24

Drinking-water distribution systems are generally designed with methodologies based on trial-and-error tests, which generate feasible results. However, these trials are not the most economical and reliable solution since they do not consider the optimization of the network. For the present work, the hydraulic model of the drinking water distribution network of San José de Cúcuta, Colombia, was optimized by applying the concept of resilience rate and minimum cost. The development of the work consisted of the hydraulic modeling of the physical components of the network in EPANET software, as well as the application of calculations of the connectivity coefficient and the unitary power of each section. With the data obtained from the modeling and calculations, the physical parameters were optimized, and the cost-benefit ratio was estimated. It was found that the current drinking water distribution system does not have a power surplus to overcome a system failure. The optimization increased the total energy surplus of the network (261%) and the resilience rate (585%). Also, the connectivity coefficient was improved with an average value of 0.95. The hydraulic optimization methodology applied resulted in a network resilient to system failures.

Study of performance and emissions in diesel engines operating with biodiesel from soybean oil and water emulsions

Orjuela Abril, Martha Sofia | 2021-01-01

Este estudio evalúa la influencia en el proceso de combustión, consumo de combustible y emisiones contaminantes en un motor diesel, que opera con biodiesel a partir de aceite de soja y emulsiones de agua con porcentajes de 4% y 8%. Para este estudio, se utiliza un motor diesel estacionario que opera en cuatro condiciones de par diferentes y una velocidad de rotación fija de 3400 rpm. Los combustibles de prueba son diésel, biodiésel de aceite de soja y emulsiones de agua SB4W y SB8W. Los resultados indican que SB4W y SB8W provocan una reducción del 6% en el poder calorífico y un aumento del 18% y del 1% en la viscosidad y densidad. Sin embargo, la presencia de agua en el biodiésel puede ayudar a reducir el BSFC del motor en un 8%. El SB4W y SB8W permiten una reducción del 23% en las emisiones de NOx. Con el uso de combustible SB4W se obtiene una reducción del 16%, 29% y 14% en CO, HC y opacidad del humo en comparación con el biodiésel de aceite de soja. Se recomienda la inclusión máxima de 8% de agua en el biodiesel de aceite de soja ya que un porcentaje mayor puede provocar la presencia de combustiones incompletas.

Design of a Resilient and Eco-friendly Microgrid for a Commercial Building

Sepúlveda, Sergio | 2021-01-01

Los desastres naturales recientes, como los huracanes Harvey y María, han causado una gran interrupción en la red eléctrica. Por otra parte, las autoridades gubernamentales se han fijado metas ambiciosas para reducir las emisiones de gases de efecto invernadero. Por lo tanto, existe un interés creciente en hacer que los sistemas de energía eléctrica sean más resilientes y con un impacto mínimo al medio ambiente. En este trabajo, se utilizó el software HOMER Grid para modelar microrredes que se contienen sistemas fotovoltaicos, baterías de ión-litio, generadores de gas natural y la carga eléctrica de un edificio de oficinas que consume un promedio de 2 MWh por día. Se modificaron los tamaños de los componentes para determinar la configuración con el generador más pequeño que pudiera suministrar energía durante un corte de energía de dos días en verano. Se realizaron análisis ambientales y económicos para mostrar las diferencias entre los diferentes objetivos de diseño del sistema. Los resultados indican que la instalación de una microrred en un edificio de oficinas con un arreglo fotovoltaico de 600 kW y una batería de ión-litio de 2.8 MWh puede evitar la emisión de hasta 287 toneladas de CO2 por año. La misma configuración de microrred puede soportar un apagón de dos días durante la mayor demanda eléctrica en la temporada de huracanes sin la necesidad de un generador de respaldo. Las microrredes jugarán un papel importante en la transición a una red inteligente porque proporcionan energía confiable, hacen que el sistema sea más tolerante a fallas de la red y permiten una alta penetración de energía renovable en la red eléctrica, lo que en consecuencia reduce el impacto ambiental.

Impacto socio-económico, político y ambiental de los asentamientos humanos en la periferia de la ciudad

Paz Montes, Luisa Stella | 2021-05-01

La investigación proporciona los resultados del Impacto socioeconómico, político y ambiental de los asentamientos humanos en la periferia de la ciudad de Cúcuta. La investigación tuvo un enfoque mixto, porque se utilizó el método descriptivo y el estudio de campo, permitiendo obtener información primaria de los sujetos mediante encuestas estructuradas aplicadas en la localidad respectiva y consulta a fuentes secundarias. La población corresponde a las familias que están ubicadas en la periferia de la ciudad de Cúcuta, se utilizó el muestreo no probabilístico bajo la técnica de muestreo aleatorio, permitiendo seleccionar 200 familias que cumplen las características y condiciones del estudio. Se evidenció una comunidad con características vulnerables generalizada por falencias de estructuración de vivienda y alto índice de asentamiento humando trayendo como consecuencia abandono o deficiente atención por parte del Estado, la ausencia total de servicios públicos como saneamiento básico, debido a las precarias condiciones en las que habitan la inmensa mayoría de los individuos que allí residen. La totalidad de los núcleos familiares están conformados por madres solteras cabezas de familia con uno o tres hijos, que se desempeñan como trabajadoras independientes, su nivel de educación es básico y le permite trabajar en empleos de oficios varios. El servicio de salud, es deficiente, no existe seguridad social integral. Por último, se constató que los miembros de las familias no cuentan con las condiciones habitacionales adecuadas, ya que la gran mayoría de estos poseen un solo cuarto donde realizan diversas actividades.

The Covid-19 pandemic in low- and middle-income countries, who carries the burden? Review of mass media and publications from six countries

Chackalackal, Dhia Joseph | 2021-03-04

During the Covid-19 pandemic, rich countries employed lockdown and physical distancing policies for transmission control. However, the question still remains whether these measures are also suitable in countries with a fragile economy, which rests mainly on the informal sector. The impacts of lockdown measures in disadvantaged population strata in six low- and middleincome countries (LMICs) were reviewed using i) 93 media reports and ii) 17 published scientific papers. This review showed that those who suffered the most from the lockdown were migrants, workers in the large informal sector, small businesses, slum dwellers, women and elderly, revealing the social, cultural and economic inequalities of societies. Financial and food support for the poor was inadequate and sometimes mismanaged. In the better organized societies, the resilience was stronger (South Korea, Kerala/India) but here also the poor had to suffer the most. It is strongly recommended that outbreak response strategies should particularly focus on the poor and vulnerable population.

Detection of water leaks with Dowsing technique and Reynold's transport theorem

García Guarín, J | 2021-05-22

Zahorí techniques are traditionally used to detect water currents in land for subsequent extraction. On the other hand, water leaks represent economic losses in factories and residences. It is enough to survey a city and determine the exaggerated number of residential leaks. Once the leak appears, a corrective action must be taken, this action is founded in itself and in the problems derived from this failure; and it is that knowing the exact location of a leak is risky if strictly collateral damage appears in the property. This research proposes to complement two different techniques, the first detects the presence of water based on the Dowsing search, and the second uses the Reynolds Transport Theorem to detect the leak relying on numerical methods and computational simulation. The Dowsing search proved to be reliable to detect the presence of water, the Reynolds Transport Theorem, yields the location of the leak with an average relative error of 10.6727% and the computational simulation corroborates Darcy's Law. Therefore, the method proposed in this investigation is sufficient for the corrective management of leaks.

Physical parameters for the estimation of the return coefficient in the sewer of the La Chivera watershed

calixto, nelson javier | 2021-06-10

Estimating the amount of flow carried by the sanitary sewer system in a locality is essential for the design of new facilities. Having a record of the flow rates allows the adequate hydraulic design of a drainage system. The objective of this work is to determine the physical parameters for the estimation of the return coefficient that allows estimating the flow rates for the sanitary sewer of the La Chivera watershed, San José de Cúcuta, Colombia. In this sense, dry weather monitoring of the wastewater in the study area was carried out. The data collected in the field were used to construct the hourly flow variation curve or inflow hydrograph in the drainage system. The average hourly flow parameters were estimated with a value of 205.7 m3/h, a value recorded at the 11th hour of the day. Similarly, the average daily flow was determined with a value of 180.3 m3/h, while the maximum peak factor was 1.14. Finally, through the physical parameters of the sanitary sewer, the return coefficient was determined, which is 0.72, a value that represents the conditions of the study area.

Development of an electro-pneumatic system for the practical training of pneumatic processes in the university environment

Rojas Suárez, Jhan Piero | 2021-06-11

This article describes the implementation of an electro-pneumatic test bench, which allows the availability of a physical environment to promote learning. The aim of the paper is to create a tool that enables practical training and research of pneumatic processes for university students in the field of engineering. The control and automation system of the test bench is made up of wired logic panels, timers, and programmable logic controllers, which are integrated into a control board configured at 24 V (direct current) to guarantee safety. Additionally, ergonomic principles were considered for the construction of the electro-pneumatic bench, thus favoring the accessibility and safety of the users. Based on national and international regulations, working pressure of 9 bar and an approximate pressure drop of 0.07 bar were defined. The construction of the test bench is considered an educational strategy to facilitate and accelerate the learning process of the students. Additionally, the development of the electro-pneumatic bench allowed the dynamic characterization of double-acting actuators by integrating experimental data and numerical models. This allowed the detailed analysis of the displacement, velocity, and acceleration variables in this type of actuator, which contributes to the physical study of pneumatic systems.

Physics in the structure and form of the architectural project. Museum of Contemporary Art Niterói, Brazil

CORONEL, LUZ KARIME | 2021-06-10

This article analyzed the formal, functional, and structural aspects of the Museum of Contemporary Art Niterói in Brazil, by identifying the criteria associated with architecture and physics; this is to establish the importance of the analysis of the architectural project to obtain the basic skills of the architect. A mixed methodological framework was used, the quantitative phase was developed from a questionnaire under a non-probabilistic sample allowed to recognize the formal, structural, and functional aspects of the work under study, the qualitative phase used an interview that established the value represented by the recognition of the application of physics in architecture. As a relevant finding, it is highlighted a basic understanding of the physical elements applied to architecture, specifically in the case of Museum of Contemporary Art Niterói, Brazil, and that they recognize the importance of the analysis of architectural works as a pedagogical tool that favors obtaining the basic skills of the architect.

Teaching the concept of the uniform plane wave from mathematical modeling

Medina Delgado, Byron | 2021-06-10

The discovery of electromagnetic waves enabled us to understand electricity, magnetism, and optics under the same field; therefore, it is important for electronic and related engineers to understand the concept of the uniform plane wave, which represents the simplest case of an electromagnetic wave propagating through a medium. However, this concept is taught with a theoretical approach, shows a need for a methodological change towards experimentation to mitigate poor learning in students causing a high failure rate in electromagnetism courses. In this context, this work presents a methodological alternative for teaching the concept of the uniform plane wave, combining the CUVIMA model with the didactics of mathematical modelling, to link experimentation and provide cognitive support to the conceptualization of the physical phenomenon. For it, a single-group design is implemented, with pre-test and post-test, to know about previous ideas and identify the conceptual change achieved for the students. When applying the Student's t-test at a significance level of 5%, a significant difference is evident between the means of the study groups. It is concluded that there is a favorable and representative conceptual change in the students, with respect to the understanding of the physical phenomenon represented by the concept of the uniform plane wave.

Effect of concentration areas in sensitive analysis of a hybrid solar Brayton cycle

Moreno Gamboa, Faustino | 2021-06-11

A simple hybrid solar thermal Brayton cycle plant thermodynamic model is evaluated in northern Colombia, where the maximum solar radiation values in the country are found. The model considers the different irreversibilities of the cycle and is coupled to a model for estimating direct solar radiation as a complementary energy source for the plant. The stability in the operation of the cycle is determined by a combustion chamber that complements the energy supply. As a result of the analysis, this work presents the sensitivity analysis of different operating parameters of the plant as a function of the areas of the concentration ratio of the solar system when the contribution of this system is maximum. It is observed that fuel consumption is reduced by 34.7% when increasing the concentration ratio between 200 and 700.

Impact of colchicine on leaf morphology and stomatics of Kalanchoe tubiflora (Harv.) Raym.- Hamet (Crassulaceae)

SALAZAR MERCADO, SEIR ANTONIO | 2021-09-24

The demand of medicinal plants for consumption is greatly increasing worldwide. The conventional breeding programs are generally dependent on the environment prone to biotic and abiotic stresses. These added to the low content of secondary metabolites at harvest, bring the need for artificial development of polyploid individuals as an alternative to increase productivity. Consequently, the present study evaluated the effect of different colchicine concentrations and exposure time, on Kalanchoe tubiflora leaf morphology and stomata. Initially, K. tubiflora seedlings were harvested and submitted to colchicine concentrations of 0, 0.025, 0.05 and 0.1 % and at two exposure times (24 and 48 hours). Subsequently, morphological measurements such as plant height, leaf width, leaves number, leaf length, leaf thickness and leaf volume every 15 days were made for 16 weeks after planting. Then, the stomata were characterized, taking into account the width, length, stomatal index and the number of chloroplasts per stoma. A significant increase in leaf morphology was found in colchicine treatments of 0.025 % at 48 h and 0.1 % at 24 h. A significant increase in stomatal morphology with the treatment of 0.025 % at 24 h was also recorded. This shows that the correct application of colchicine in term of quantity and time could produce greater growth in a short period and increase the biomass of K. tubiflora medicinal plant

Underlying variables in the understanding of movement in engineering students

Gamboa Suárez, Audin Aloiso | 2021-08-26

This article describes the understanding of motion by active students taking Newtonian physics for engineering, supported by active learning, during the pandemic due to COVID-19; in addition, an unsupervised predictive model of learning achievement was constructed from variables identified using the principal component analysis technique on the responses. the instrument used is the modified test of understanding graphs-kinematics comprehension. students from two universities in Bogotá, Colombia participated. The results show a lower level of accuracy in students in remote face-to-face mode, compared to the reference group of physical presence; by way of reflection, the forced educational experiment implies resizing the teaching activity in the teaching and learning of movement.

Didactic Engineering as a research method in physics teaching

Avendaño Castro, William Rodrigo | 2021-08-26

Several mathematical concepts have application in physics; this paper reports the results of a pedagogical investigation based on the methodology known as didactic engineering, which has been proposed with the aim of improving the skills exhibited by a group of eleventh grade students from a private institution in the interpretation of kinematic graphs. The concept of the slope of the straight line and how this mathematical concept can represent velocity or acceleration according to the variables considered in the kinematics graph provided was enhanced in the pedagogical intervention. This methodology offers a process of internal validation, after comparing the results obtained in a knowledge test at two different points in time (pre-test and post-test). The results allowed us to identify improvements in all students in terms of basic kinematics graph interpretation skills, and a group of students stood out by advancing in more complex reasoning and interpretation processes. These results contribute to the improvement of the pedagogical practices of Physics teachers at secondary and middle school levels, making them more competent when they enter higher education.

Analysis of heat fluxes in ceramic block type building pieces

Sanchez Molina, Jorge | 2021-09-02

In Norte de Santander, Colombia, there is a ceramic cluster made up of 59 companies dedicated to the production of construction materials derived from clay, a vernacular material with a wide extraction potential in the region. Fired clay products in different hollow block presentations represent 15% of industrial production, these construction pieces are low cost and show a high demand in the local masonry market, therefore, their thermo-physical characteristics largely build the thermal envelope of “Cucuteña”. This research comparatively evaluates the thermal behavior of four types of ceramic blocks with different perforations, applying the finite element method in thermal simulations that consider a conductivity of 0.407 W/m°C in the ceramic to establish the influence of the shape on the temperature distribution and heat flow profiles of each piece subjected to environmental conditions of a warm semi-arid climate, with average maximum temperatures of 33 °C and an average maximum solar radiation of 796.8 Wh/m² under extreme climatic conditions in the city of San Jose de Cúcuta, Colombia. The results of the study allow identifying the ceramic block of 6 rectangular holes as the product that, due to its physical characteristics, presents a better alternative to be applied in constructions that seek thermal efficiency.

Fluid-dynamic study of the behavior of the air inside a textile Stenter

Parra, J W | 2021-09-03

In the textile industry, drying is one of the most important processes. This process requires large investments and high energy consumption, which generates high costs for companies in this sector. In this work, a modeling of the behavior of the air was carried out in a textile Stenter, under real operating conditions through the development of fluid-dynamic simulations. For the computational modeling of the problem, a 3D geometry was constructed based on measurements taken from an injector of a textile Stenter. The standard k-ε turbulence model was used in the turbulent flow solution. The equations of the model were solved numerically using the finite element method. The standard k-epsilon turbulence model proved to be a model capable of reproducing the behavior of the air in the injectors of the textile Stenter.

Factors shaping the COVID‑19 epidemic curve: a multi‑country analysis

Su Yeon, Jang | 2021-10-02

Lockdown measures are the backbone of containment measures for the COVID-19 pandemic both in high-income countries (HICs) and low- and middle-income countries (LMICs). However, in view of the inevitablyoccurring second and third global covid-19 wave, assessing the success and impact of containment measures on the epidemic curve of COVID-19 and people’s compliance with such measures is crucial for more effective policies. To determine the containment measures influencing the COVID-19 epidemic curve in nine targeted countries across high-, middle-, and low-income nations.