Now showing items 201-220 of 1587

Analysis of variables related to the mass flow of gaseous emissions in beehive ovens

mendoza lizcano, sonia maritza; Palacios Alvarado, W; Medina Delgado, Byron (Reino Unido, 2021-05-22)

In the combustion processes of the ceramic industry, large amounts of pollutant gas concentration are generated, so it is necessary to measure the system and the physical phenomenon, as well as the variables inherent to ...
Qos-based pattern recognition approach for web service discovery: Ar_wsds(Article)

Adarme Jaimes, Marco Antonio; Jimeno, Miguel (Suiza, 2021-08-31)

Web service composition requires high levels of integration and reliability of the services involved in its operation, which must meet specific quality criteria to ensure their proper execution and deployment. The discovery ...
Analysis of the characteristics of combustion, emissions, and energy efficiency of blends of heptanol with pure diesel fuel in compression ignition engine(Article)

García, C.P; PABON LEON, JHON ANTUNY; FONSECA VIGOYA, MARLEN DEL SOCORRO (Italia, 2021-09)

The objective of this research is to study the influence of the heptanol content in conventional diesel fuel in different proportions for the evaluation of the combustion parameters, emissions, and energy efficiency. For ...
An application of physics: simply supported bridges made of post-tensioned concrete and structural steel beam

Márquez Peñaranda, J F; Pineda Rodríguez, J R; Rojas Suárez, J P (Journal of Physics: Conference SeriesReino Unido, 2022-01-06)

Bridges represent an important application of physics capable of solving real transportation problems. Knowledge of convenience of different mechanical solutions when analyzing and designing bridge is needed. For these ...
Smartphone and teamwork as a methodological tool for teaching and learning physics

Malndonado, E A; Ramírez, P; Avendaño Castro, William Rodrigo (Journal of Physics: Conference SeriesReino Unido, 2022-01-05)

This research is based on the usefulness of mobile phones as a tool for students to learn about uniform rectilinear motion in vertical free fall, based on experimental practice. To evaluate whether these mobile devices ...
Training action for physics teachers: an application of problem-based learning

Prada Núñez, Raul; C A, Hernández Suarez; Gamboa Suarez, A A (Journal of Physics: Conference SeriesReino Unido, 2022-01-05)

The teaching of problem-based learning is a didactic approach that requires a radical change in the role of the physics teacher because it is focused on learning, research, and reflection that students follow to reach a ...
Impact of a science and technology strategy on the learning of physics

Ramirez Leal, Pastor; Maldonado Estevez, E A; Avendaño Castro, William Rodrigo (Journal of Physics: Conference SeriesReino Unido, 2022-01-05)

The use of smartphones and some applications for educational purposes are valuable tools in the laboratory since they are motivating for students and the teacher can take advantage of this advantage for the teaching of ...
Educación virtual en tiempos de COVID-19: percepciones de estudiantes universitarios

Avendaño Castro, William Rodrigo; Luna, Enrique O.; rueda vera, gerson (La Serena, Chile, 2021-10)

El objetivo de esta investigación es describir las percepciones de un grupo de estudiantes universitarios de nivel de pregrado en torno a la educación virtual en tiempos de COVID-19. El enfoque es cuantitativo, cuenta ...
Difficulties in the interpretation of kinematics graphs in secondary basic education students

Prada Núñez, Raul; Gamboa Suárez, A A; Avendaño Castro, William Rodrigo (Journal of Physics: Conference SeriesReino Unido, 2022-01-05)

This research reports the findings derived from the identification of the difficulties exhibited by a group of 76 students from different grades of basic secondary education in a private educational institution with an ...
Computational tool for learning electrostatic physics through the development of a disruptive methodology

Ramírez Carvajal, Luis Eduardo; Puerto, Karla; Castro Casadiego, Sergio (Journal of Physics: Conference SeriesReino Unido, 2022-01-05)

A computational tool for learning electrostatic physics is presented through the development of a disruptive methodology. The tool allows the analysis of case studies based on Coulomb’s law, Gauss’s law, Poisson’s equation, ...
Simulation study of phase change materials operating in thermoelectric devices

Orjuela Abril, Martha Sofia ; Pabón León, J A; Rojas Suárez, J P (Reino Unido, 2021-06-04)

In this paper, a computerized analysis is performed to evaluate the effect of phase change materials on the performance of thermoelectric generators. This study was conducted using commercial OpenFOAM software. Analyze ...
Development of a numerical methodology for evaluating physical properties and technical specifications in thermoelectric devices

Prada Botia, Gaudy Carolina; Rojas Suárez, J P; Orjuela Abril, Martha Sofia (Reino Unido, 2021-06-04)

Typically, the performance evaluation of thermoelectric devices is done using experimental methods and analytical models, which require detailed information on the thermoelectric properties of the materials that make up ...
Determination of the expansion capacity by calcination of the clays from San José de Cúcuta, Colombia

Márquez, J F; Cáceres, J R; Palacios, J D (Reino Unido, 2021-06-04)

Viscoplasticity and pyroplasticity of clays are important characteristics to control in production processes of lightweight concrete aggregates. When clay is calcined under temperatures above 1,000 ℃, its volume increases. ...
Use of strontium aluminate powders in the photocatalytic removal of dyes present in water

Benítez Guerrero, N S; Rolón Rodríguez, Y M; Peña Rodríguez, G (Reino Unido, 2021-06-04)

The removal of Iris No. 17 fabric dye in water using strontium aluminate powders doped with europium and dysprosium, and the radiation from an ultraviolet C lamp during photocatalysis, is reported. The degradation of the ...
Determination of the structural efficiency of short bridges according to their physical and economic characteristics

Pineda Rodríguez, J R; Rojas Suárez, J P; Prato Duarte, Fabian Alberto (Reino Unido, 2021-06-04)

Bridges are structures designed and built to overcome natural and artificial obstacles. The analysis and design of bridges is carried out following principles of physics applied to engineering. The aim is to estimate the ...
Characterization of physical properties of bismuth-titanium coatings on 316L stainless steel

GARZÓN AGUDELO, PEDRO; palacios alvarado, wlamyr; Medina Delgado, Byron (Journal of Physics: Conference SeriesReino Unido, 2022-01-05)

The 316 L steel is a type of stainless steel widely used in the medical industry, which in recent years has been studied for different uses in society. Being an engineering material, it is imperative to know its performance ...
Topological stereotomic structure with the use of palm rachis applying material physics to architectural design

Cadena González, I M; Vergel Ortega, Mawency; GALLARDO PÉREZ, HENRY DE JESÚS (Reino Unido, 2021-06-04)

The use of ancestral construction techniques in wood has evolved throughout history, but consequently many species have been disappearing after indiscriminate logging; but the use of renewable materials is what is needed ...
Evaluation of recycled asphalt pavement in Colombia

Yung Vargas, Yee Wan; Rondón-Quintana, Hugo Alexander; Cordoba Maquilon, Jorge Eliecer (Journal of Physics: Conference SeriesReino Unido, 2022-01-06)

Reclaimed asphalt pavements are obtained from existing pavements through recovery techniques and are used for new asphalt mixtures production with the inclusion of virgin aggregates and asphalt cement, constituting ...
Characteristics of refractory bricks used in the coke production kilns in Colombia

Gelves Diaz, John Freddy; Sánchez Zuñiga, J; Sánchez Molina, Jorge (Reino Unido, 2021-06-04)

A study has been carried out on the main physicochemical characteristics of the refractory bricks that are currently used in traditional coke-making kilns in Colombia. Two classes of material (brick) used in this industry ...
Effective thermal properties and proximate analysis of coke-coal fines mixtures

Soto Rivero, M F; Quintero Garzón, A C; Peña Rodríguez, G; Miranda Molina, L A; Sepulveda Solano, G (Reino Unido, 2021-06-04)

We report the effective thermal properties at room temperature and proximate analysis of three mixtures of coke and carbon fines formed by uniaxial pressing at 30 MPa. Using differential scanning calorimetry and ...

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Analysis of variables related to the mass flow of gaseous emissions in beehive ovens
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mendoza lizcano, sonia maritza | 2021-05-22

In the combustion processes of the ceramic industry, large amounts of pollutant gas concentration are generated, so it is necessary to measure the system and the physical phenomenon, as well as the variables inherent to the process, for subsequent estimation in terms of physical magnitudes, and a dimensional analysis, this allows to generate approximations in the causal relationships of the variables. The objective of the research is to analyze the behavior of the variables involved in the process and the influence of the mass flows of polluting gases. An exploratory and experimental methodology was used, for this, the data were taken with the technique of direct measurement in the sources of gas emissions and subsequently subjected to simulation in software such as AMOS V24.0 and LISREL V8.8., on the other hand, the data were subjected to an exploratory and confirmatory factorial analysis, using SPSS software version 24.0. As a result, the variables capacity and production are practically identical, which leads to a high correlation and, consequently, an undesired multicollinearity between the variables, so the suggestion is to omit one of them. On the other hand, the sulfur percentage variable is inversely correlated with most of the variables and its saturation is not clear, so it is theoretically sustained as a latent variable of the SO2 indicator.

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Qos-based pattern recognition approach for web service discovery: Ar_wsds(Article)
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Adarme Jaimes, Marco Antonio | 2021-08-31

Web service composition requires high levels of integration and reliability of the services involved in its operation, which must meet specific quality criteria to ensure their proper execution and deployment. The discovery and selection of web services currently face optimization problems. Many services might satisfy a requirement with similar quality criteria. Because of this, software developers have to choose the most appropriate services for a given composition, complicated by the rapid increase in providers and services available in the cloud. Service composition also implies coupling according to a composition flow and non-functional requirement criteria. Such requirements make selection and composition a complex task not previously solved in the literature. This paper presents Ar_WSDS, a computational approach for web services discovery and selection in cloud environments, which bases its implementation on the brain’s pattern recognition systematic functioning. This process allows classifying web services through recognition modules created dynamically based on their quality parameters, resulting in a set of web services suitable for a web service composition. This approach allows a solution to the selection problem using less complex tasks. This paper introduces an architectural and procedural definition that provides the web service description with a pattern to recognize and select services using different recognition levels. We simulated our approach and evaluated it using a dataset from the QWS project that offers a set of quality criteria collected from different providers. The web services are recognized and classified using different quality criteria for the composition and each of their services. The results demonstrate the effectiveness of the discovery and selection process compared to other approaches. Furthermore, Ar_WSDS allows us to recognize and filter out web services with ambiguity and similarity in their provider information, a process that minimizes the discovery space for services.

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Analysis of the characteristics of combustion, emissions, and energy efficiency of blends of heptanol with pure diesel fuel in compression ignition engine(Article)
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García, C.P | 2021-09

The objective of this research is to study the influence of the heptanol content in conventional diesel fuel in different proportions for the evaluation of the combustion parameters, emissions, and energy efficiency. For the above, three heptanol blends identified as HP4%, HP8%, and HP16% have been used with a percentage of heptanol of 4%, 8%, and 16%, respectively. The tests have beencarried out on a single-cylinder stationary diesel engine at a constant load (9 Nm) and a rotational speed of 2800 rpm, 3200 rpm, and 3600 rpm. The results show that the percentage of heptanol causes an increase in the maximum values of the pressure in the combustion chamber and the heat release rate. In general, the presence of heptanol in conventional diesel produces an increase of 3.9% and 4.8% in the maximum values of these parameters. Additionally, the HP4%, HP8%, and HP16% heptanol blends allow reducing CO2, NOx, and smoke opacity emissions by 11.7%, 6.7%, and 37.1%, respectively. Due to the closeness of the physicochemical properties between the blends of heptanol and conventional diesel, a similarity between the energy and exergy performance between both fuels has been obtained. The above demonstrates the potential of heptanol to be used as a renewable fuel without the need for modifications to the engine. In addition, they have the ability to reduce NOx emissions, which is a problem in various types of biodiesel.

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An application of physics: simply supported bridges made of post-tensioned concrete and structural steel beam
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Márquez Peñaranda, J F | 2022-01-06

Bridges represent an important application of physics capable of solving real transportation problems. Knowledge of convenience of different mechanical solutions when analyzing and designing bridge is needed. For these reasons, this work is focused on the study of convenience of using two types of bridges. Simply supported short-medium span bridges (30 m to 45 m) are usually excessively long when choosing reinforced concrete solutions and usually short for other types of structures such as cable-stayed or cantilever bridges. The suitability of simply supported bridges leads to the need of studying their cost benefit ratios. This work studies the cost benefit ratio for post-tensioned concrete beams and structural steel girders in simply supported straight bridges. Eight models built of type I sections were used in both cases to analyze the bridges using a software based on the stiffness method. Span of each bridge was set to 30 m, 35 m, 40 m, and 45 m. The convenience of each type of bridge was done comparing the total and the cost per linear meter of each solution (post-tensioned and structural steel). Comparison was done using material consumption, labor, and construction processes costs only. Also, allowable vertical displacement given by current bridge design standards was verified

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Smartphone and teamwork as a methodological tool for teaching and learning physics
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Malndonado, E A | 2022-01-05

This research is based on the usefulness of mobile phones as a tool for students to learn about uniform rectilinear motion in vertical free fall, based on experimental practice. To evaluate whether these mobile devices allow better learning on the subject, a pre-test/post-test design was carried out with 43 students participating in the 9th grade in natural sciences. McNemar and Stuart-Maxwell non-parametric tests were applied. The proposal on the experimental practice gave satisfactory results when comparing the pre-test and post-test, in the analysis of the particular and global form of the answers.

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Training action for physics teachers: an application of problem-based learning
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Prada Núñez, Raul | 2022-01-05

The teaching of problem-based learning is a didactic approach that requires a radical change in the role of the physics teacher because it is focused on learning, research, and reflection that students follow to reach a solution to a problem situation as a starting point for the acquisition and integration of knowledge in science. The results of a training action for physics teachers on the implementation, their perceptions, and perspectives on the feasibility of the problem-based Learning approach are presented. The study is quasi-experimental in nature with pre-test and post-test in the study variables. The results suggest that the teachers' perceptions are positive, which is why they consider that its implementation in teaching is viable, however, they need more elements that facilitate their execution in the classroom, such as understanding the theoretical foundations and their pedagogical use successful in the classroom. It is concluded that, for the physics teaching process, problem-based learning is an innovation because it allows the student to learn actively, in which inquiry is relevant for the development of skills and appropriation of knowledge, which in the framework of natural sciences leads to the reconstruction of the scientific method.

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Impact of a science and technology strategy on the learning of physics
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Ramirez Leal, Pastor | 2022-01-05

The use of smartphones and some applications for educational purposes are valuable tools in the laboratory since they are motivating for students and the teacher can take advantage of this advantage for the teaching of physics. The experience is based on the anthropological theory of didactics and the teaching approach in science, technology, engineering, and mathematics. It is proposed to investigate a trigger question in physics. To respond, an application is used that uses the smartphone’s sensors to record the simulation data. The experience is described, and results of its implementation are presented. Methodologically, a qualitative descriptive approach was used in a group of tenth grade students taking the physics course. Finally, it is concluded that the students felt motivated since they felt they participated in the construction of their own learning, supported using technologies that facilitate the integration of knowledge in physics.

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Educación virtual en tiempos de COVID-19: percepciones de estudiantes universitarios
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Avendaño Castro, William Rodrigo | 2021-10

El objetivo de esta investigación es describir las percepciones de un grupo de estudiantes universitarios de nivel de pregrado en torno a la educación virtual en tiempos de COVID-19. El enfoque es cuantitativo, cuenta con un diseño no experimental-transversal, y es de tipo descriptivo. Se empleó como instrumento un cuestionario tipo Likert con 31 ítems, a una muestra de 608 estudiantes de la facultad de ciencias empresariales de una universidad pública de la ciudad de Cúcuta (Colombia). Los resultados muestran que la educación virtual en tiempos de COVID-19 para el escenario de investigación y la muestra de participantes ha sido adecuada y efectiva en las distintas dimensiones analizadas. Se concluye que la percepción en general de los estudiantes universitarios es favorable frente a la educación virtual, particularmente, respecto del papel que han tenido los docentes en cada uno de sus cursos y materias.

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Difficulties in the interpretation of kinematics graphs in secondary basic education students
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Prada Núñez, Raul | 2022-01-05

This research reports the findings derived from the identification of the difficulties exhibited by a group of 76 students from different grades of basic secondary education in a private educational institution with an emphasis on science education. The students were given a questionnaire presenting five situations based on the Position-Time graph associated with uniform rectilinear motion of particles. The research approach is of a quantitative nature at a descriptive level with a field design, since it was the students who filled in the instrument. It is highlighted as a finding in the opinion of the students that the subject has been seen in class, but due to the teacher’s methodology it is not fully understood by them. The results show that the students have a long list of difficulties mainly due to the lack of articulation of mathematical concepts in physical contexts, a situation that prevents them from analyzing the proposed statements, reasoning about the approaches, and improving in the process of searching for alternative solutions with clear arguments.

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Computational tool for learning electrostatic physics through the development of a disruptive methodology
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Ramírez Carvajal, Luis Eduardo | 2022-01-05

A computational tool for learning electrostatic physics is presented through the development of a disruptive methodology. The tool allows the analysis of case studies based on Coulomb’s law, Gauss’s law, Poisson’s equation, and Laplace’s equation with boundary value. The tool was tested using reference exercises for each case study, making use of quantitative and qualitative comparative analysis between the traditional mathematical development and the computational tool. Errors were measured using Likert scale. The quantitative results showed errors of less than 1.8% in all the cases studied, concluding that the tool is effective. The qualitative results showed that the methodology allows a better development of the electrostatics learning process, dynamizing the study of complex topics such as electromagnetic physics theories through interactivity and technological resources, in addition to having a theoretical module developed using agile methodologies that provide dynamism and an intuitive environment to the interface.

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Simulation study of phase change materials operating in thermoelectric devices
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Orjuela Abril, Martha Sofia | 2021-06-04

In this paper, a computerized analysis is performed to evaluate the effect of phase change materials on the performance of thermoelectric generators. This study was conducted using commercial OpenFOAM software. Analyze changes in temperature, potential and efficiency due to phase change materials. The study evaluated a variety of geometric and operational conditions, such as changes in material height and heat flux. The results obtained indicate that the presence of phase change material allows a significant increase in the temperature difference between the surfaces. The temperature difference is increased by 35% with a height of 3.25 mm. The temperature difference increases the potential of the thermoelectric generator and increases the maximum output voltage by 21%. Overall, phase change materials have been shown to improve thermoelectric efficiency by 23%. For test conditions, the maximum efficiency is 4.77%. From this result, it can be concluded that the phase change material is a promising alternative for improving the low efficiency of thermoelectric generators due to their heat storage capacity.

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Development of a numerical methodology for evaluating physical properties and technical specifications in thermoelectric devices
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Prada Botia, Gaudy Carolina | 2021-06-04

Typically, the performance evaluation of thermoelectric devices is done using experimental methods and analytical models, which require detailed information on the thermoelectric properties of the materials that make up the thermoelectric devices. However, this type of information is generally not available. Due to this situation, the present investigation seeks to develop a numerical methodology to determine the performance of thermoelectric devices, using technical reference specifications that are normally provided by the manufacturer, such as maximum current, maximum voltage, maximum temperature difference, and efficiency. The numerical model is made up of a series of equations based on thermoelectric phenomena, which generates a contribution in the area of physics. The results obtained are validated through experimental comparisons and the technical data of the thermoelectric devices. The comparison between the different results shows a maximum error of 5%. Therefore, the developed methodology is considered a robust tool for the realistic analysis of the performance of thermoelectric generators and thermoelectric coolers. The foregoing will allow massive use of this type of device in industrial applications and its commercial accessibility.

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Determination of the expansion capacity by calcination of the clays from San José de Cúcuta, Colombia
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Márquez, J F | 2021-06-04

Viscoplasticity and pyroplasticity of clays are important characteristics to control in production processes of lightweight concrete aggregates. When clay is calcined under temperatures above 1,000 ℃, its volume increases. For this reason, it is important to investigate how much volume can gain a given clay before using it in production of lightweight aggregates. This research work has evaluated the expansive capacity of some Colombian clays, applying to them static heat treatment in furnaces at temperatures above 1,000℃. The theoretical background of this work is based on the state of the art of production processes of lightweight clay-based aggregates, which were used to determine if the available clay is a precursor of lightweight aggregate. Also, chemical characteristics were determined using X-ray fluorescence tests. Raw material was chosen from several clays existing in San José de Cúcuta, Colombia. The clays were processed until particles’ diameters resulted smaller than 75 µm. Using these particles, pellets with diameter varying from 10 mm to 15 mm were formed. To determine the expansion capacity and the reduction of volumetric density, volume and weight of pellets were measured before and after applying the heat treatments. When the clay presented a low expansion capacity, technological nutrients were added to the mixtures attempting to maximize the expansion capacity of the pellets. A swelling of up to 3.24 times the initial size of pellets was observed. technological nutrients based on organic matter were chosen and applied in a proportion of 1: 4, i.e., one gram of technological nutrients was added to 4 g of clay. The density of manufactured aggregates resulted to be between 0.50 g cm! ⁄ and 1.93 g cm! ⁄ . Clay mixtures added with technological nutrient showed density lower than 1 gram per cubic centimeter, this means that they could float on water

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Use of strontium aluminate powders in the photocatalytic removal of dyes present in water
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Benítez Guerrero, N S | 2021-06-04

The removal of Iris No. 17 fabric dye in water using strontium aluminate powders doped with europium and dysprosium, and the radiation from an ultraviolet C lamp during photocatalysis, is reported. The degradation of the dye was studied by UV-Vis spectrophotometry, for two concentrations of strontium aluminate powder and five of the dye for one hour. The chemical composition and morphology of strontium aluminate powders was studied using X-ray scattered energy spectroscopy, X-ray fluorescence and scanning electron microscopy. The pH, total dissolved solids, and electrical conductivity of the water samples before and after treatment were measured using the Handy-Lab 680 multiparameter. It is evident in the morphology of the strontium aluminate powders a synthesis by reaction in solid state, and a chemical composition by weight of strontium oxide and small amounts of europium and dysprosium. The photocatalytic treatment reports an efficiency of 100% in the removal of the dye for the strontium aluminate powder concentration of 500 mg/L, while for 1000 mg/L an efficiency of 98% was found, likewise for a concentration of 60 mg/L and one hour of ultraviolet radiation a first order reaction kinetics in the degradation of the dye was evidenced.

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Determination of the structural efficiency of short bridges according to their physical and economic characteristics
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Pineda Rodríguez, J R | 2021-06-04

Bridges are structures designed and built to overcome natural and artificial obstacles. The analysis and design of bridges is carried out following principles of physics applied to engineering. The aim is to estimate the structural efficiency of short bridges according to their physical and economic characteristics through equations that measure the cost tendency, identifying which ones have the highest structural efficiency for a given length between supports. The design of short bridges was carried out by means of a mathematical modeling in a software based on finite elements. A comparative cost analysis was carried out for various types of short vehicular bridges designed with reinforced concrete decks supported by reinforced concrete beams; post-tensioned concrete beams; and structural steel beams. It was determined that the bridge with a reinforced concrete deck is the alternative with the best structural efficiency according to its physical and economic characteristics with spans of 12 meters and 18 meters. According to the estimated cost equations, it is concluded that, from 18.49 meters post-tensioned concrete bridges are the most efficient physically and economically. Structural steel bridges are the least structurally efficient for short bridges. Therefore, the construction of short vehicular bridges with structural steel is not feasible.

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Characterization of physical properties of bismuth-titanium coatings on 316L stainless steel
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GARZÓN AGUDELO, PEDRO | 2022-01-05

The 316 L steel is a type of stainless steel widely used in the medical industry, which in recent years has been studied for different uses in society. Being an engineering material, it is imperative to know its performance based on its physical and mechanical properties that allow identifying the response of this steel in addition to thin films as coatings. Bismuth and titanium have been recently used to improve the properties of 316 L steel, so they were used in this study. The sol-gel technique was used as the film forming method. The response of physical and mechanical properties was evaluated from the analysis of microhardness and coefficient of friction reported for the different types of steel-coating systems. Higher microhardness values were found for films with higher proportion of titanium. The coefficient of friction values is influenced by the system used, with higher values obtained for samples with a single coating layer.

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Topological stereotomic structure with the use of palm rachis applying material physics to architectural design
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Cadena González, I M | 2021-06-04

The use of ancestral construction techniques in wood has evolved throughout history, but consequently many species have been disappearing after indiscriminate logging; but the use of renewable materials is what is needed in the present and in the future after the global pollution and the ecological footprint of materials such as iron or concrete, so it is necessary to glimpse new building materials from a renewable approach. To this end, this research focuses on the application of physicochemistry and physics of materials to establish the feasibility of using Attalca Butyracea palm rachis as a sustainable material with a novel application in the field of architecture. For this purpose, a methodology of morphological configuration is applied that appropriates the identification of specific physical properties together with notions of geometry and topology applying the concept of topological stereotomic configuration from the operational tools and morphological actions of the Lucas Períes fold, resulting in a proposal for a topological stereotomic structure applied to the architectural design of buildings in the municipality of Pelaya, Colombia.

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Evaluation of recycled asphalt pavement in Colombia
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Yung Vargas, Yee Wan | 2022-01-06

Reclaimed asphalt pavements are obtained from existing pavements through recovery techniques and are used for new asphalt mixtures production with the inclusion of virgin aggregates and asphalt cement, constituting environmentally friendly mixtures at a lower total cost, by requiring fewer quantities of new materials. This research, unlike the studies found on the subject, focuses on the study of reclaimed asphalt pavement by analyzing its granulometric distribution and asphalt cement content. For this purpose, representative reclaimed asphalt pavement samples were taken from four Colombia cities, to verify their heterogeneity. The obtained reclaimed asphalt pavement was analyzed in the laboratory, to obtain the material granulometric distribution, through extraction and asphalt content tests, following Colombian regulations from the “Instituto Nacional de Vías”. The results show that the granulometry of all cities has a central tendency (average) that moves towards an upper limit in the 2 mm particles. When analyzing the granulometry separately of the four cities, it is observed that they present a different trend in their granulometry, which shows their heterogeneity. The asphalt cement content presented values between 4.0% and 5.0%.

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$Portada Characteristics of refractory bricks used in the coke production kilns in Colombia$

Characteristics of refractory bricks used in the coke production kilns in Colombia
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Gelves Diaz, John Freddy | 2021-06-04

A study has been carried out on the main physicochemical characteristics of the refractory bricks that are currently used in traditional coke-making kilns in Colombia. Two classes of material (brick) used in this industry were collected, which come from a geographical area of the country that supplies brick to many kiln builders. These materials were characterized by X-ray diffraction and fluorescence, scanning electron microscopy, dilatometry, thermal conductivity, pyroscopic resistance, and percentage of water absorption. The results obtained show that these materials have had very low firing temperatures in the factory, which is evidenced in the dilatometry, microscopy and water absorption percentage data. This characteristic brings with it high firing shrinkages when subjected to high temperatures (> 4% at 1,200 °C). There is a high presence of quartz in the material (40% or more), an aspect that increases the risk of fissure formation. Chemically there is a limited aluminum content (between 22% and 23%) compared to other reference refractories. The onset of fusion of these materials occurs around 1,360 °C. The thermal conductivity obtained can be considered moderate (between 0.634 W⁄mK and 0.760 W⁄mK), thus demonstrating limited applicability as an insulator.

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Effective thermal properties and proximate analysis of coke-coal fines mixtures
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Soto Rivero, M F | 2021-06-04

We report the effective thermal properties at room temperature and proximate analysis of three mixtures of coke and carbon fines formed by uniaxial pressing at 30 MPa. Using differential scanning calorimetry and thermogravimetry, the thermal behavior of the carbon samples was determined. The KD2 Pro® system was used to measure the effective thermal properties, while the proximate analysis was carried out applying the ASTM D 3172-89 standard. It was found for coke fines that in the range between 40.00 °C and 293.94 °C there is a loss in weight of 3.2%, which corresponds to the degradation of low molecular weight volatiles, another degradation was also observed between 90.07 °C and 336.21 °C, and the maximum devolatilization temperature was 579 °C, finally from 700 °C the melting process begins, which corresponds to the formation of coke. It was also observed that the thermal conductivity increases with increasing coke concentration in the sample, and that the mixture with the highest thermal diffusivity was the one formed with 80% coke fines and 20% carbon fines. According to the thermal properties of the samples can be to be used efficiently as fuel.

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