Mostrando ítems 1-20 de 38

Vehicular flow analysis and diagnosis of the public transport

Rojas Suárez, Jhan Piero; Orjuela Abril, Martha Sofia ; Prada Botia, Gaudy Carolina (Journal of Physics: Conference SeriesReino Unido, 2019-02-13)

Public transport is one of the major means of mobilization for the general population of a country, achieving great importance to its policies of mobilization and economic analysis because it creates controversy to have a ...
Determination of expandability clay from San José de Cúcuta metropolitan area, by adding different percentages of sewage sludge

caceres rubio, jose rafael; Rojas Suárez, Jhan Piero; Sanchez Molina, Jorge (Journal of Physics: Conference SeriesReino Unido, 2019-11-19)

This article shows the research carried out on clay from the San José de Cúcuta metropolitan area, Colombia, to which was added several percentages of a wastewater sludge, which is called as a technological nutrient. The ...
Comparison of lightening costs for reinforced concrete gantry

Prada Botia, Gaudy Carolina; Rojas Suárez, Jhan Piero; Orjuela Abril, Martha Sofia (Journal of Physics: Conference Series, 2019-11-19)

The selection of suitable materials for a construction defines the costs and characteristics that can contribute to the building, being of vital importance to make a correct choice. Lightening is an element to reduce costs ...
A review about the use of industrial by-products in the lightweight aggregates production of expanded clay

caceres rubio, jose rafael; Sanchez Molina, Jorge; Rojas Suárez, Jhan Piero (Journal of Physics: Conference SeriesReino Unido, 2019-11-19)

The fabrication lightweight aggregates in recent years has included the addition of industrial by-products in the expanded clay manufacture as modifier agents of the expansion capacity, and also as a destination for the ...
Determination of expandability clay from San José de Cucuta metropolitan area, by varying calcination temperature and time

Sanchez Molina, Jorge; caceres rubio, jose rafael; Rojas Suárez, Jhan Piero (Journal of Physics: Conference SeriesReino Unido, 2019-11-19)

In this article, the volumetric change of the clay granules and sewage sludge (technological nutrient), San José de Cúcuta metropolitan area raw materials, when calcined at different temperatures and different burning times ...
Mineralogical, microstructural and porosimetry analysis in three different clayey soils

Rojas Suárez, Jhan Piero; Ruge, J C; Palacios, X; Molina-Gómez, F (Journal of Physics: Conference SeriesReino Unido, 2019-11-19)

Diffraction, scanning electron microscope and helium porosimetry techniques have been shown to be suitable for obtaining physical and mineralogical properties in soil samples. The X-ray fluorescence spectroscopy allows ...
Cost comparison between reinforced concrete moment resistant gantry system and reinforced concrete industrialized structural wall system

Rojas Suárez, Jhan Piero; Prada Botia, Gaudy Carolina; Orjuela Abril, Martha Sofia (Journal of Physics: Conference SeriesReino Unido, 2019-11-19)

The system of porticoes resistant to moments of reinforced concrete is a set of beams and columns connected by means of knots that allows the generation of adequate spaces with facility before changes by the same users, ...
Technical feasibility study for the implementation of pedestrian safety mechanisms

Rojas Suárez, Jhan Piero; Orjuela Abril, Martha Sofia ; Prada Botia, Gaudy Carolina (Journal of Physics: Conference SeriesReino Unido, 2019-11-19)

The increase in distractions when driving or walking on a road has proportionally increased the number of accidents that occur each year, with pedestrians being the most affected. For this reason, an attempt is made to ...
Management of urban solid waste in the two first decades of the XXI century in the city of San José de Cúcuta, Colombia

Carrillo Soto, Gustavo Adolfo; Rojas Suárez, Jhan Piero; Sayago Ortega, Juan Carlos (Journal of Physics: Conference SeriesReino Unido, 2019-11-19)

The research developed in this study is exploratory, descriptive and the quantitative method, it characterizes the urban solid waste of the ten communes of the city of San José de Cúcuta and compares the results obtained ...
Operational data set of a 2 MW natural gas-fired generation engine at shutdown times

Valencia Ochoa, Guillermo; Rojas Suárez, Jhan Piero; Duarte Forero, Jorge (Data in BriefPaíses Bajos, 2020-06)

In this paper, operational data of a natural gas-fired generation engine at 2 MW of power is presented. This engine is used as part of the power supply system of a flexible packaging transformation and conversion plant. ...
Numerical simulation to evaluate the influence of geometric parameters on the physical behavior of heat e

Rojas Suárez, Jhan Piero; Pabón León, Jhon Antuny; Orjuela Abril, Martha Sofia (Journal of Physics: Conference Series, 2021)

In the present investigation, a methodology was developed by means of numerical simulation for the evaluation of the influence of the geometric parameters of the heat exchangers used in thermoelectric generation devices. ...
Development of a gravimetric fuel measurement system for the evaluation of engine performance physical parameters

Prada Botia, Gaudy Carolina; Rojas Suárez, J P; Orjuela Abril, M S (Reino Unido, 2021)

This paper presents the implementation and design features of a gravimetric-based fuel consumption system. The proposed system comprises a gravimetric balance with serial output, a fuel pump, and a control valve that are ...
Experimental and CFD Study of a Centrifugal Fan Performance Under ANSI/AMCA Standard

Rojas Suárez, Jhan Piero; Villada Castillo, Dora Clemencia; Flórez Solano, Eder (International Journal on Engineering ApplicationsItalia, 2021)

Centrifugal fans are widely employed for several technical applications in science and engineering due to their easy employment and practical use. Therefore, in this work, the centrifugal airfoil performance has been studied ...
Operational Failure Detection Applied to Heat Exchange Systems Using State Observer Method

Rojas Suárez, Jhan Piero; Espinel Blanco, Edwin; Florez, Eder (International Review of Automatic ControlItalia, 2021)

The role of computational modeling is becoming predominant in the exploration and evaluation of new technologies. Numerical simulations have solved the most complex phenomena immersed in thermal sciences by the implementation ...
2D Simulation of Two-Phase Flow for Water Jet Cutting Processes with OpenFOAM

Florez, Eder; Rojas Suárez, Jhan Piero; Espinel Blanco, Edwin (Italia, 2021)

Cold cutting processes are characterized to perform the kinetic energy needed to cut hard materials with little mechanical effort by means of the ultra-high flow pressure pumps, which produce water jets with a flow pressure ...
Hydraulic modeling of combined sewers overflow integrating the results of the swmm and CFX models

Pulgarín, D A; De Plaza, J S; Ruge Cárdenas, Juan Carlos; Rojas, J P (Revista Internacional de Metodos Numericos para Calculo y Diseno en IngenieriaEspaña, 2021-01-19)

This study proposes a methodology for the calibration of combined sewer overflow (CSO), incorporating the results of the three-dimensional ANSYS CFX model in the SWMM onedimensional model. The procedure consists of ...
Document details - A numerical model for the analysis of the bearings of a diesel engine subjected to conditions of wear and misalignment

Pardo García, Carlos Eduardo; Rojas Suárez, Jhan Piero; Orjuela Abril, Martha Sofia (LubricantsSuiza, 2021-04-09)

In the present work, a numerical model is developed to investigate the influence of wear and misalignment on the bearings of a stationary diesel engine. The model implemented considers the effects of surface wear on the ...
Analysis of the influence of textured surfaces and lubrication conditions on the tribological performance between the compression ring and cylinder liner

Pardo García, Carlos Eduardo; Rojas Suárez, Jhan Piero; Orjuela Abril, Martha Sofia (LubricantsSuiza, 2021-05-06)

The objective of the present investigation is to analyze the tribological performance between the union of the cylinder liner and the compression ring under the influence of surface texturing and different lubrication ...
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 ...
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 ...

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Vehicular flow analysis and diagnosis of the public transport
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Rojas Suárez, Jhan Piero | 2019-02-13

Public transport is one of the major means of mobilization for the general population of a country, achieving great importance to its policies of mobilization and economic analysis because it creates controversy to have a poor quality of service, directly affecting the users and drivers of these means. Due to the above, an alternative is proposed for the decongestion of main public transport routes, presenting the degree of saturation and the performance index that can create different alternative routes by moving a percentage of the routes in the city of Cúcuta, Colombia. In order to evaluate the effectiveness of this solution, information was collected by means of surveys for users and drivers, analyzing the data with the SPSS version 21 software, manifesting that there is low quality in public transport. In this way, the final characteristics of this method are evaluated in the new alternatives and in the problem sector, satisfying the quality requirements of public transport worldwide.

LEER
Determination of expandability clay from San José de Cúcuta metropolitan area, by adding different percentages of sewage sludge
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caceres rubio, jose rafael | 2019-11-19

This article shows the research carried out on clay from the San José de Cúcuta metropolitan area, Colombia, to which was added several percentages of a wastewater sludge, which is called as a technological nutrient. The objective of the study is to find out with what percentage of technological nutrient the capacity of expansion of the granules is maximized. The methodology that was followed consists of four phases; preparation of raw materials; pelletizing of raw materials in granules of 5 to 10 millimeters; application of heat treatment in a rotary kiln at the pilot plant level; and application of descriptive statistics for analysis of results. It was determined that the mixture with a 20% of technological nutrient, produces the highest volumetric expansion ratio, with 1.56 times its initial size, while, when adding 30% of the nutrient the same expansion occurs when adding an 10% nutrient, which is 1.07 times the initial size of the particle.

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Comparison of lightening costs for reinforced concrete gantry
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Prada Botia, Gaudy Carolina | 2019-11-19

The selection of suitable materials for a construction defines the costs and characteristics that can contribute to the building, being of vital importance to make a correct choice. Lightening is an element to reduce costs and optimize resources, adding a better index of resistance against earthquakes, being of vital importance the good choice of this: concrete, clay or EPS. In this investigation a comparison of costs and incidence of the three types of lighteners that are used in the construction of three levels houses with reinforced concrete portico based on the requirements of NSR-10 was made by means of statistical samples/data, graphs and tables of data analysis, on the quotations and information collected from different studies on lightening costs in structures.

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A review about the use of industrial by-products in the lightweight aggregates production of expanded clay
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caceres rubio, jose rafael | 2019-11-19

The fabrication lightweight aggregates in recent years has included the addition of industrial by-products in the expanded clay manufacture as modifier agents of the expansion capacity, and also as a destination for the disposal of waste and residues in countries where lightweight concrete is used for the construction of high-rise structures. This article provides a review of the use of by-products as additives in the production of lightweight aggregates from expanded clay available in the literature. As a methodology, the bibliographic search was used through the consultation of specialized databases such as Sciencedirect and other documentary sources of open access scientific journals in several countries. The selection criteria for documents were specified according to the frequency the by-product use. 58 references on investigations by-products addition to the lightweight aggregates production were revised. In conclusion, the study of the use of Colombian byproducts as additives in the expanded clay aggregates production is suggested as a research subject due to the absence of articles related to this topic.

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Determination of expandability clay from San José de Cucuta metropolitan area, by varying calcination temperature and time
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Sanchez Molina, Jorge | 2019-11-19

In this article, the volumetric change of the clay granules and sewage sludge (technological nutrient), San José de Cúcuta metropolitan area raw materials, when calcined at different temperatures and different burning times is shown. The main objective is to evaluate out the work right conditions (temperature and time), for the production of light aggregates from expanded clay. The methodology that was followed consists of three phases: preparation and pelletization of clay mixtures and technological nutrient; application of heat treatment in a set of muffle furnaces; and application of statistical treatment with the help of Software R. One of the most important results is that the expansion of the clay is indifferent to the time it takes to cook the pellets, and that this property depends solely on the temperature of burning. The temperature that generates the greatest expansion is 1,200 Celsius degrees, using a set of muffle furnaces.

LEER
Mineralogical, microstructural and porosimetry analysis in three different clayey soils
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Rojas Suárez, Jhan Piero | 2019-11-19

Diffraction, scanning electron microscope and helium porosimetry techniques have been shown to be suitable for obtaining physical and mineralogical properties in soil samples. The X-ray fluorescence spectroscopy allows obtaining the elemental composition of the sample, while the X-ray diffraction technique permits obtaining a qualitative and quantitative composition of the soil minerals. On the other hand, scanning electron microscope shows the microstructure of the soil and the helium porosimetry measures the pore size, volume, distribution, density and other porosity-related characteristics of the material. This document presents the characterisation of three different clayey soils by an experimental plan that included mineralogical, microstructural and porosimetric tests. The soils used were bentonite, kaolin and a natural clay retrieved near to Bogotá city, Colombia. Results obtained from this study allow providing a better understanding of soil behaviour, which traditional mechanical tests do not explain.

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Cost comparison between reinforced concrete moment resistant gantry system and reinforced concrete industrialized structural wall system
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Rojas Suárez, Jhan Piero | 2019-11-19

The system of porticoes resistant to moments of reinforced concrete is a set of beams and columns connected by means of knots that allows the generation of adequate spaces with facility before changes by the same users, whereas the industrialized system of structural walls of reinforced concrete, they are used for numerous, repetitive and of low price real estate, but they are completely immobile and in some occasions with problems of segregation and anthills. In this research work, a comparative study of the costs and budgets of the two proposed structural systems of the building was carried out in order to determine the structural system with the lowest costs and execution times, showing the results in explanatory graphs.

LEER
Technical feasibility study for the implementation of pedestrian safety mechanisms
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Rojas Suárez, Jhan Piero | 2019-11-19

The increase in distractions when driving or walking on a road has proportionally increased the number of accidents that occur each year, with pedestrians being the most affected. For this reason, an attempt is made to study the characteristics of a vehicle road, identifying the critical points and road sections of maximum demand of the inhabitants, who are the ones most in need of pedestrian crossings. For this reason, a statistical and technical study of traffic is proposed by means of vehicular gauges with respect to the most representative days that help to determine quantitatively the vehicular flow that circulates through this road corridor, by means of graphs, tables that help to identify the statistical data without still leaving aside the importance of a study of pedestrian traffic by means of a count in typical days of mobilization with the purpose of determining the pedestrian volume, due to its increase in the indexes of accidents caused by different types of transport, in which the motorcycles stand out.

LEER
Management of urban solid waste in the two first decades of the XXI century in the city of San José de Cúcuta, Colombia
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Carrillo Soto, Gustavo Adolfo | 2019-11-19

The research developed in this study is exploratory, descriptive and the quantitative method, it characterizes the urban solid waste of the ten communes of the city of San José de Cúcuta and compares the results obtained with those of a similar investigation carried out 20 years. This comparison concludes that there have been significant changes in solid waste generated in the city, increasing food waste, cardboard, plastic, glass and cans and decreasing garden waste, paper and metals. In addition, surveys were conducted indicating that about one third of the population makes waste separation evidencing the existence of the recycling culture.

LEER
Operational data set of a 2 MW natural gas-fired generation engine at shutdown times
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Valencia Ochoa, Guillermo | 2020-06

In this paper, operational data of a natural gas-fired generation engine at 2 MW of power is presented. This engine is used as part of the power supply system of a flexible packaging transformation and conversion plant. This plant, besides having the power supply generated by the engine, receives electrical energy from the network. The data collected from this engine corresponds to measurements taken before, during and after engine stops, whether due to engine maintenance stops, engine failures or external power grid failures. The measurement was made every 10 seconds, and for the storage of these data a data acquisition software was used, which, besides allowing to take these data, shows in real time the electrical behavior of the electrical supply system, as well as the mechanical behavior of the engine.

LEER
Numerical simulation to evaluate the influence of geometric parameters on the physical behavior of heat e
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Rojas Suárez, Jhan Piero | 2021

In the present investigation, a methodology was developed by means of numerical simulation for the evaluation of the influence of the geometric parameters of the heat exchangers used in thermoelectric generation devices. The validation of the proposed methodology was carried out through experimental tests on a diesel engine test bench under four load conditions (2 Nm, 4 Nm, 6 Nm, and 8 Nm) and a constant speed of 3600 rpm. The results obtained show that the methodology proposed by means of the numerical simulation presents a high concordance with the behavior described experimentally. The deviation between the simulation predictions and the experimental results was less than 4%. Additionally, it was evidenced that the change in the geometry of the heat exchanger has a considerable impact on the parameters of heat flow and surface temperature. It was shown that a 50% reduction in fin distance causes an increase of 2% and 2.4% in the previous parameters. Through geometric modifications, the electrical power generated increased by 7.9%. In general, the methodology developed through numerical simulation allows the analysis of the physical, thermal, and hydraulic phenomena present in heat exchangers focused on use in thermoelectric devices.

LEER
Development of a gravimetric fuel measurement system for the evaluation of engine performance physical parameters
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Prada Botia, Gaudy Carolina | 2021

This paper presents the implementation and design features of a gravimetric-based fuel consumption system. The proposed system comprises a gravimetric balance with serial output, a fuel pump, and a control valve that are integrated into a complete engine test bench via Arduino UNO®. The study implements an instrumentation methodology to minimize measurement disturbance and error propagation, which represents a major concern in engine experimental testing. Moreover, an interactive virtual environment is developed to reinforce user interaction via LabView™. Results demonstrated that the proposed measurement system features robust and reliable operation while maintaining negligible disturbance and overall uncertainty ranging from 0.010-0.23 g/s. Additionally, it was evidenced that the measurement system allows the analysis of key parameters to evaluate engine performance. The study of the fuels blends shows that the ethanol content causes a 6.8% increase in brake specific fuel consumption and a 4% decrease in the brake thermal efficiency. Due to the low cost of the developed measurement system can be easily adapted to test bench laboratories to promote a better learning process and in industrial sectors for better energy management.

LEER
Experimental and CFD Study of a Centrifugal Fan Performance Under ANSI/AMCA Standard
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Rojas Suárez, Jhan Piero | 2021

Centrifugal fans are widely employed for several technical applications in science and engineering due to their easy employment and practical use. Therefore, in this work, the centrifugal airfoil performance has been studied with experimental and computational fluid dynamics techniques in order to improve their energy efficiency influenced by the rotor-stator interaction. In this sense, this research proposes a study of the main components' aerodynamic performance in order to determine the optimal operating conditions for different geometries of the impeller blades. In order to validate the simulation results, an experimental study has been performed to configure the design of experiments with the data acquisition of velocity and pressure values of the air mass flow under different conditions in the test bench configured with the ANSI/AMCA 210-07 standard. The experimental procedure has been performed with 2500 rpm, like a constant value of the centrifugal fan's angular velocity. The experimentally acquired data have allowed validation and the definition of each treatment's response to establish a linear regression model in order to predict centrifugal fan performance under different working conditions. 5.4 kPa has been determined as the high static pressure value for different impeller blade configurations conformed by the blades' angle, number, and length features.

LEER
Operational Failure Detection Applied to Heat Exchange Systems Using State Observer Method
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Rojas Suárez, Jhan Piero | 2021

The role of computational modeling is becoming predominant in the exploration and evaluation of new technologies. Numerical simulations have solved the most complex phenomena immersed in thermal sciences by the implementation of sophisticated mathematical algorithms. This study incorporates a stationary thermodynamic model in order to evaluate the main operational parameters and the overall performance of heat exchange systems based on energy and exergy viewpoints while implementing unknown inputs. Moreover, the study introduces a UIO state observer technology in order to facilitate the early prediction of failure events in heat exchange systems using a detect, isolate and identify (FDI) methodology. Therefore, the proposed model has induced different fault conditions in order to examine the overall performance while integrating error state of signals criteria from the relative difference between the real and modeled estimates. The outcomes have demonstrated a good agreement for the estimated values of the mathematical algorithm considering the imminent presence of disturbance and interference that promotes modeling error. Finally, the results have outlined that the estimations of real operation conditions are not affected by the unknown inputs.

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2D Simulation of Two-Phase Flow for Water Jet Cutting Processes with OpenFOAM
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Florez, Eder | 2021

Cold cutting processes are characterized to perform the kinetic energy needed to cut hard materials with little mechanical effort by means of the ultra-high flow pressure pumps, which produce water jets with a flow pressure value of around 90 ksi. These manufacturing processes may be studied considering the fluid mechanics' principles that describe the transport phenomena for inviscid, continuous, and incompressible laminar flows in order to obtain theoretical results approximated to the process conditions. In this sense, the numerical modeling techniques applied in the analysis of water jet cutting processes define an efficient solution of the processes due to the physical analysis of the partial differential equations, which quantify the abrasive flow particles into the system. Taking into account the above, this research proposes a numerical analysis of the physical phenomena through the two-phase flow simulation in steady state with OpenFOAM. Abrasive and liquid phases are quantified to study the turbulent values, which describe the water jet behavior under different working conditions. A 2D model has been computed and discretized, considering the nozzle features in order to visualize and predict the abrasive mixture and flow rejected by using a low computational effort. Therefore, this numerical approach has been validated with a mesh independency analysis developed to verify the relation between the numerical data and the finite number of nodes computed in order to discretize a computational domain and to solve analytically the system proposed until reaching a high approximation between the model and the experimental values obtained during the cutting process by means of abrasive flows.

LEER
Hydraulic modeling of combined sewers overflow integrating the results of the swmm and CFX models
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Pulgarín, D A | 2021-01-19

This study proposes a methodology for the calibration of combined sewer overflow (CSO), incorporating the results of the three-dimensional ANSYS CFX model in the SWMM onedimensional model. The procedure consists of constructing calibration curves in ANSYS CFX that relate the input flow to the CSO with the overflow, to then incorporate them into the SWMM model. The results obtained show that the behavior of the flow over the crest of the overflow weir varies in space and time. Therefore, the flow of entry to the CSO and the flow of excesses maintain a non-linear relationship, contrary to the results obtained in the onedimensional model. However, the uncertainty associated with the idealization of flow methodologies in one dimension is reduced under the SWMM model with kinematic wave conditions and simulating CSO from curves obtained in ANSYS CFX. The result obtained facilitates the calibration of combined sewer networks for permanent or non-permanent flow conditions, by means of the construction of curves in a three-dimensional model, especially when the information collected in situ is limited.

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Document details - A numerical model for the analysis of the bearings of a diesel engine subjected to conditions of wear and misalignment
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Pardo García, Carlos Eduardo | 2021-04-09

In the present work, a numerical model is developed to investigate the influence of wear and misalignment on the bearings of a stationary diesel engine. The model implemented considers the effects of surface wear on the bearing, cavitation effects, and surface roughness. For the numerical analysis, changes in the surface roughness of σ = 0.75 µm, σ = 1 µm, and σ = 1.25 µm are defined, and changes in the bearing load of 50%, 75%, and 100%. The results demonstrated that increasing the surface roughness intensifies the bearing wear, which represents 18% and 140% of the bearing clearance for the roughness of σ = 1 µm and σ = 1.25 µm, respectively. Additionally, the surface roughness causes a considerable increase in the bearing wear rate. The results described a maximum wear rate of 20 µm/s. In general, increasing the bearing load by 25% doubles the hydrodynamic pressure conditions increases friction force by 33%, and reduces lubrication film thickness by 12%. The analysis of the angle of deflection, φx and φy, shows that the moment and the degree of misalignment tend to increase significantly with the increase in the magnitude of the angle φy. Negative angles of deflection, φx, produce a greater increase in the degree of misalignment and the moment. This implies a greater chance of contact with the bearing surface. In conclusion, the proposed methodology serves as a reliable tool to simultaneously evaluate key parameters on the tribological behavior of bearings that further extend their endurance and minimize wear damage.

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Analysis of the influence of textured surfaces and lubrication conditions on the tribological performance between the compression ring and cylinder liner
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Pardo García, Carlos Eduardo | 2021-05-06

The objective of the present investigation is to analyze the tribological performance between the union of the cylinder liner and the compression ring under the influence of surface texturing and different lubrication boundary conditions. The analysis is carried out by developing a numerical model, which involves hydrodynamic pressure, lubrication film thickness, textured surface, dynamic forces, and lubrication boundary conditions (starved lubrication and fully flooded lubrication). MATLAB® software (The MathWorks Inc., Natick, MA, USA) is used to solve the equations developed. The results show that the application of a textured surface on the cylinder liner allows obtaining a reduction of 20% and 5% in the asperity contact force and in the total friction force. Additionally, the textured surface allows for a 4% increase in MOFT. In this way, it is possible to reduce the power loss. The implementation of a boundary condition of fully flooded lubrication produces an overestimation in the total friction force due to the greater prominence of the lubrication film. Implementing a textured surface in the ring profile is an alternative way to reduce power loss. The results show that this alternative allows an 8% reduction in power loss.

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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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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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