Envíos recientes

Análisis del comportamiento del guadua “BAMBU” sometido a postensado

Granados-Páez, María Fernanda | 2019-07-01

El siguiente trabajo pretende dar a conocer el comportamiento de las propiedades de bambú sometido a postensado, a través de una investigación científica que tiene como objetivo general Aplicar ensayos de laboratorio al bambú o guadua angustifolia kunth sometida a postensado a distintas cargas axiales a lo largo de su luz. La investigación tiene un enfoque cualitativo; de la misma manera, es de carácter documental ya que se puede realizar a nivel exploratorio, descriptivo o explicativo estudiando variables independientes a partir de datos secundarios, con análisis de estos datos secundarios se puede elaborar importantes conclusiones relacionadas con el comportamiento o estado de las variables; para el análisis de los resultados se utilizaran instrumentos como fichas, computadores, y sus unidades de almacenaje, cuadros de registros. El mismo está estructurado de la siguiente manera en un primer bloque se presenta el planteamiento del problema, los objetivos del estudio y la justificación. En un segundo bloque todo lo referente a la metodología, se desarrolla el tipo y diseño de la investigación, las técnicas de recolección y procesamiento de la información. Finalmente se presentan las conclusiones.

Application of LEAN tool "line balancing" to determine the productivity of workforce in activities of plastering and internal detailing in two-story houses made of masonry

Hurtado-Figueroa, Oswaldo | 2018-11-26

The finishing work of construction represents an aggregated value that makes the difference when a client is deciding to buy a house. The stipulated costs for plastering and detail activities for houses, in occasions, surpasses 30% of the total value of the construction work, considerable costs that require constant control and supervision both in the analysis and the execution of the construction. The implementation of the LEAN philosophy in this activity is not commonly implemented due to the lack of knowledge of the tools that this method provides. This research shows the implementation of line balancing, as a LEAN tool, in the plastering and detailing activities for two-story masonry houses, constructed in the housing project Callejas del Este which took place in the city of Cucuta, Colombia. The implementation of this tool contemplated the analysis of execution times of the work crew, the results were synthesized in tables for better interpretation and conclusions of interest were developed for the improvement of the observed processes and activities.

The architecture on land and its construction techniques, millenary tradition that is reborn

Hurtado-Figueroa, Oswaldo | 2018-08-30

In the context of sustainable development, the use of materials of low environmental impact in the activities inherent to the construction of houses plays an important role when it comes to reducing waste pollution. The alternative materials to be used in the various construction processes, besides being totally renewable, they must be reusable, available locally and have little or no energy expenditure in its extraction, preparation and application. The Bio resources or Eco materials meet these requirements, of which land as ancestral material used in millenary construction techniques, it becomes the most feasible alternative for its use as a construction material to replace the conventional ones. The main objective is the literary review of articles published in reliable databases, whose research topic was based on the analysis and use of land and natural materials for application in housing construction. The articles were categorized, analyzed and integrated into a synthesized structure to extract the important aspects in the thematic introduction, the constructive techniques, the results of the processes carried out and finally, the conclusions on the constructive implementation of the elements studied. In this way it offers information of interest to people who want to delve into the subject investigated.

Behaviour of the contact trace in a cam-follower system when the displacement law has been designed using bézier curves

Acevedo Peñaloza, Carlos Humberto | 2018-11-06

The study shows the distribution of the contact trace in a cam - follower mechanism in which the Bézier curves of degrees 5, 7 and 9 have been used for the design of displacement of the follower. The equations that describe the movement of the follower and its derivatives are presented, the expressions are formulated for the contact trace, the force exerted on the mechanical assembly are formulated and the results obtained are presented in a model mechanism.

Caracterización de los materiales pétreos utilizados en la ciudad de Cúcuta para la construcción de pavimentos en proyectos viales para verificar el cumplimiento de las especificaciones INVIAS 2013 para la empresa INGPRA S.A.S

Yung Vargas, Yee Wan | 2020-02-02

Tras la necesidad del desarrollo de las vías para una ciudad y el auge de los proyectos de construcción de infraestructura la empresa INGPRA S.A.S plantea la necesidad de desarrollar un proyecto para realizar la caracterización y aplicación de los ensayos solicitados por la norma en el laboratorio de Pavimentos de la Universidad Francisco de Paula Santander con el alcance de realizar los ensayos exigidos en las especificaciones del INVIAS para agregados pétreos que conforman los materiales de base granular, subbase granular, afirmado y mezclas asfálticas que conforman la estructura de un pavimento. A partir de la complementación del laboratorio de pavimentos se caracterizará los materiales de la zona de influencia a de seis empresas que producen este tipo de materiales para la construcción de vías en el municipio de Cúcuta y sus alrededores. Como resultado del ejercicio se entregará un informe técnico a INGPRA S.A.S con los resultados de cada una de los materiales pétreos producidos por las empresas indicando de acuerdo al tipo de material el cumplimiento o no de las especificaciones exigidas por INVIAS, además quedará implementado el servicio de los ensayos adicionados al portafolio que ofrece la UFPS. Teniendo en cuenta que la empresa podrán tener actualizada la información permitiendo utilizar en sus obras materiales que cumplen las especificaciones, dando a su cliente final una obra construida con calidad, garantizando que se trabajó con materiales pétreos idóneos. La Universidad podrá certificar dichos materiales mediante los ensayos de calidad de materiales dando acompañamiento al constructor con la periodicidad que lo exige la norma en la etapa de construcción. Las especificaciones INVIAS de acuerdo a los materiales producidos en planta exige el cumplimiento en características como: Distribución granulométrica, dureza, durabilidad, limpieza y resistencia del material. Resultado del análisis de información obtenida en los ensayos de laboratorio se podrá realizar de ser el caso recomendaciones para para el mejoramiento de las características del material con el fin de ajustar estas al cumplimiento de las especificaciones técnicas exigidas por el INVIAS.

CFD study of industrial safety valves in a virtual environment with OpenFOAM® software

Rojas Suárez, Jhan Piero | 2020-11-30

Numerical advances in the numerical analysis of safety valves have enabled the development of approximated predictions related to the hydraulic behavior of turbulent flows, which influence the mechanical behavior of the main components coupled to the pneumatic system. Therefore, many studies have focused on the numerical analysis of the safety valves responsible for maintaining the system integrity subject to high-pressure values under real working conditions in a virtual and inexpensive environment through the CFD codes application with OpenFOAM software. Therefore, this paper is based on the technological prediction of the laminar or turbulent flows into a safety valve through the solution of the partial differential equations system, which describes the physical state of the pressure and mass flow rate in space and time. IcoFOAM solver has been applied to model the main flow fluctuations taken, considering the mean values of the pneumatic system. A mesh independence study has been used to compute and define the finite number of nodes and cells that discretize the continuous computational domain of the internal flow and generate an approximated numerical prediction of the safety valve performance, maintaining a low computational cost during the iterative solution of the conservation equations developed with computational tools. In this sense, the RANS KEpsilon approach has defined a high prediction of the turbulent flow behavior in a virtual environment with an error rate close to the 2 percent value between the numerical and the experimental models. This research shows a good agreement in the understanding of the physical phenomena with the computational tool application based on advanced theories of thermal and fluid mechanics sciences in a virtual environment.

¿Coaching en las empresas? La gerencia del coaching en las organizaciones contemporáneas

barrientos, ender jose | 2019-10-09

El presente estudio tiene como propósito dar la descripción global sobre la gerencia del coaching en las organizaciones contemporáneas. En el entendido que la gerencia del coaching es un proceso empresarial, la cual a través del gerente, líder o directivo, tiene la competencia y la capacidad de poder identificar y desarollar las habilidades y potencialeidades del equipo del talento humano a su cargo. Se busca la esencia de la rentabilidad y beneficio empresarial, con la modalidad del coach, un mayor índice de pertenecnia con la organización tocando el lado humano de ésta. Este proceso requiere de evaluación de indicadores, que le permitan a la gestion de negocios replantear situaciones en cuyos casos sea necesario optimizar el tiempo y los recursos. Este estudio se desarrolló con el método cualitativo, esencialmente documental bibliográfico. Se concluye que efectivamente el concepto de la Gerencia del coaching en las organizaciones contemporáneas viene a ser el proceso mediante el cual se replantea permanentemente la preparación y capacitacion del talento humano, en los escenarios gerenciales, con la presencia del liderzgo, y es el líder o gerente coach, quien debe asumir las estrategias para la innovación y formación de equipos de alto rendimiento, que ser así, elevaría la productividad del trabajo y los volúmenes de producción, respondiendo a las necesidades y expectativas del cliente, aunque existan contingencias, pues cada organización goza de su personalidad muy particular, en especial aquellas empresas u organizaciones que se han mantenido en el tiempo por ejemplo las educativas, socio formativas, industriales, deportivas, ambientales, empresariales, entre otras.

Comparative analysis of supercritical CO2 Brayton cycles with simple and partial cooling configurations

Cárdenas-Gutiérrez, Javier Alfonso | 2020-09

The theoretical analysis of the thermodynamic cycles and the physical processes that occur in a cyclical way has improved the knowledge needed to improve the energy efficiency and the performance of the energy transfer systems in science and engineering. Power generation, cooling, and heating processes are improved by means of numerical methods to study the thermodynamic changes of flows involved in the energy transfer between mechanical devices coupled in industrial processes. Taking into account the growing concern in the recent years for the developing of the new power production schemes related to the steam or gas flows applied to non-conventional sources like solar radiation, residual heat production, wind energy, and, biomass combustion, this paper proposes a thermodynamic analysis of supercritical carbon dioxide (S – CO2) Brayton cycle considering new alternatives of power generation in order to satisfy the elevated energy demand with the improvement of the physical parameters simulated in the thermodynamic model. The first and the second laws of thermodynamics are computed in the mathematical algorithm applied in order to solve the steady-state of the flow pressure and the heat transferred during the power production under different working conditions. The simple and partial cooling configuration is studied in this research considering the less complex features of the supercritical carbon dioxide cycle with the aim to validate the prediction of the mathematical algorithm applied with MATLAB software and verify the improvement of the thermodynamic configuration proposed in this research. A good agreement has been reached during the numerical validation of the model with an error rate of less than 2 percent between the numerical data analyzed with a computed model.

A comparative study of the energy, exergetic and thermo-economic performance of a novelty combined Brayton S-CO2-ORC configurations as bottoming cycles

Cárdenas-Gutiérrez, Javier Alfonso | 2020-07-14

This paper presents a comparative study on the energy, exergetic and thermo-economic performance of a novelty thermal power system integrated by a supercritical CO2 Brayton cycle, and a recuperative organic Rankine cycle (RORC) or a simple organic Rankine cycle (SORC). A thermodynamic model was developed applying the mass, energy and exergy balances to all the equipment, allowing to calculate the exergy destruction in the components. In addition, a sensitivity analysis allowed studying the effect of the primary turbine inlet temperature (TIT, PHIGH, rP and TC) on the net power generated, the thermal and exergy efficiency, and some thermo-economic indicators such as the payback period (PBP), the specific investment cost (SIC), and the levelized cost of energy (LCOE), when cyclohexane, acetone and toluene are used as working fluids in the bottoming organic Rankine cycle. The parametric study results show that cyclohexane is the organic fluid that presents the best thermo-economic performance, and the optimization with the PSO method conclude a 2308.91 USD/kWh in the SIC, 0.22 USD/kWh in the LCOE, and 9.89 year in the PBP for the RORC system. Therefore, to obtain technical and economic viability, and increase the industrial applications of these thermal systems, thermo-economic optimizations must be proposed to obtain lower values of the evaluated performance indicators.

Computational fluid dynamics analysis of combined cycle power plant heat exchanger with OpenFOAM® software

Cárdenas-Gutiérrez, Javier Alfonso | 2020-10

The heat exchangers application in combined cycle power plants is a key aspect in the thermal and fluid mechanics sciences due to their elevated functionality in industrial processes related to the quality and the efficiency in the power generation. Heat exchangers are employed in thermal processes in order to remove a significant heat flow and to maintain temperature values under different working conditions. Taking into account the above, numerical methodologies have been developed with the aim to study and analyze the heat exchanger performance based on the thermal states of its physical values in space and time. Experimental methods may be applied to create models and describe the flow behavior in function of mass flow rate, pressure, and flow temperature in different measure points of the finite volume. However, it is necessary to apply numerical methods linked to computational tools in order to generate a high flow description into the heat exchanger under real working conditions. Therefore, this paper proposes a numerical analysis of the flow transported into a heat exchanger with computational tools to predict its performance under real Combined Cycle Power Plant conditions through a virtual environment. Random number generator KEpsilon turbulence model and Eulerian – Eulerian multiphase model is coupled in a Computational Fluid Dynamics code to solve the system of the partial differential equations which describes the flow behavior and heat transfer into the heat exchanger, and numerical results have been compared against the experimental model in order to verify the flow prediction of the simulation methodology employed in this particular case. The good agreement reached between the models defines an inexpensive way to evaluate and optimize the heat exchanger performance by means of OpenFOAM software.

Cytotoxic evaluation of sodium hypochlorite, using Pisum sativum L as effective bioindicator

SALAZAR MERCADO, SEIR ANTONIO | 2019-05-30

Delay at bus stops of Metrolinea transport system, based on parameters measured "in situ". Case study Bucaramanga-Colombia

Peña, Carlos A. | 2018-10

The purpose of this research is to determine the theoretical capacity of the Metrolinea transport system according on delay at bus stop predictive model, based on parameters measured “in situ”. The Metrolinea is an integrated mass transportation system (SITM) which was developed in Bucaramanga, Colombia, and is based on the concept of a bus rapid transit (BRT) with fixed stops in exclusive places. It has a design, service and specialized infrastructure. It follows a trunk line structure interconnecting the three neighboring municipalities of Bucaramanga, Floridablanca and Piedecuesta, guaranteeing their use and high passenger demand. The project consists of a delay model at bus stops along the different stops of the trunk corridor that connect these three municipalities, allowing us to predict the most useful parameter. The methodology developed in situ consists of visual observation, executed in the existing trunk, and has an approximate length of 16.8 Km. The distance between each of its stations is variable, ranging from 230m to 2980m. The measuring requires one to board the bus, record the times spent during the journey, calculating the one with the highest demand, recording the flow of passengers, as well as calculating the delay times, interruptions and incidents. The data was collected in the year 2017 on market days. The calculation methodology used is contained in the manual of transit capacity and quality of service (TCQSM), this allowed us to determine the calculations corresponding to the theoretical capacity of the system and delay at the bus stops model.

¿El Derecho a la salud?, gestión detrás de las rejas en la Fría estado Táchira - Venezuela

barrientos, ender jose | 2019-10-08

La presente investigación tiene como propósito, destacar el deterioro a la salud de las personas que están en centros de reclusión; en estado Táchira, Venezuela; a quienes le es casi imposible poseer éste derecho que debe estar conforme a la dignidad de la persona, ya que se encuentra a la espera de poder asistir ante un Juez de Control de Garantías, o bien esperando su sentencia y/o libertad; el Estado obvia el derecho a la salud, que es un derecho social básico, establecida en nuestra carta magna, sin tomar en consideración que existen internos que por falta de atención médica pueden desarrollar complicaciones en su patología o entrar en crisis depresivas como una reacción frente a su nueva situación. La atención de salud es un derecho fundamental de todo ser humano y que las circunstancias del cuidado sanitario en las cárceles perturban a la salud pública. Se utiliza una investigación documental y recolección de datos, que se efectúa a través de la observación documental, como también se realiza la interpretación jurídica; tomando en cuenta los criterios jurisprudenciales.

Determination of the quality of coarse aggregates for the elaboration of concrete mixes from 3 water sources in the City of Cucuta-Colombia

Hurtado-Figueroa, Oswaldo | 2018-12-07

A comparative analysis was performed on the mineral material extracted from 3 water sources in the city of Cucuta, from the rivers Tachira, Pamplonita and Zulia to determine the viability of their incorporation in the concrete mixtures for the construction of rigid floors. There were visits to the companies Preconcretos Trituradora la Roca y Concretos, and Tirurados, in charge of the material extractions, where samples of the crushed material "coarse aggregate" from each of the water sources were taken respectively. The granulometry of the coarse aggregate was performed according to the arranged parameters in the NCT 174 whose results were determinant for the conclusions. The trial of degradation to abrasion to each of the samples was executed, taking as guide the indications described by the Colombian INV-218-13 standard. The results obtained in the trial were analyzed and compared with the parameters stipulated by the INV standard described for the % of the degradation limit allowed for coarse aggregate for its usage as concrete material in the construction of rigid floors. It was concluded that each of the extracted materials from the water sources were viable according to the data obtained from their comparison.

Determination of the theoretical stress concentration factor in structural flat plates with two holes subjected to bending loads

Acevedo Peñaloza, Carlos Humberto | 2018-11-22

Numerous research works have studied the stress distribution in sections with geometric discontinuities and the relationship with the theoretical factor of stress concentration using the finite element method. These works have dealt with topics such as the influence of the length of pieces on the 𝐾�𝑡� factor in rectangular orthotropic plates; The behavior of the stress concentration factor on short shafts with section changes under bending loads; The theoretical factor of stress concentration in flat parts subjected to tension with "U" grooves; The estimation of the theoretical stress concentration factor 𝐾�𝑡� for a flat plate with two holes subjected to tension loads. Other studies have compared the stress distribution by applying three methods: elasticity theory, finite element analysis and experimental techniques. Results show that the finite element method is effective in solving the problem. The goal of this research is to determine the theoretical stress concentration factor for a flat plate with two holes subjected to bending applying the finite element method. The modeling of the plate, the application of the loads, the mesh generation and the simulation of the stress distribution were made using the software ANSYS® Workbench. Four holes with different sizes were worked and for each of them 10 different values of the distance between centers were taken. In this way the relationship between the factor 𝐾�𝑡�, the size of the holes and the distance between centers was found. This information is of great importance for the design of mechanical elements that are under these conditions.

Diseño de teja modular ventilada en resina y arcilla sin cocer

Daza, Natalia | 2019-01-01

En muchas ocasiones se han buscado alternativas a los materiales con que se cubren las viviendas, y uno de los materiales más usados es la teja criolla, un material hecho con barro dándole forma y horneado después, es por ello que el objetivo de este trabajo fue proponer una teja en resina y arcilla sin cocimiento alguno, con esto se pretende mejorar el cómo se cubren las viviendas y ahorrando energía en su cocción, este trabajo fue de corte documental y descriptivo, ya que se analizaron materiales los cuales se propusieron para la realización de la teja, con esto se espera mejorar el desempeño de la teja antes utilizada con base a conseguir un material con un menor peso y menor costo.

Las estructuras industrializadas como elemento innovador bajo el contraste de las percepciones de los ingenieros

Cárdenas-Gutiérrez, Javier Alfonso | 2020-04

The objective of the research was to make known the experiences of calculating engineers in the face of the behavior of industrialized buildings in earthquakes of great magnitude in the departments of Santander and Norte de Santander, Colombia. This industrialized construction system for houses was taken as object of study due to its novel implantation in the departments. The planning, execution and application of the 2010 seismic standard applied in Colombia in the field of building construction was analyzed. In addition to the field experiences of the professionals and university professors of both departments, the research was based mainly on the technical knowledge of the specialists. These two characteristics were taken into account due to the absence of information on the structural behavior under earthquakes of great magnitude of the buildings constructed with the system in the departments. The interpretative method was used with the support of the computer-assisted qualitative analysis program ATLAS.ti, which allowed the association of codes through the relationships of the interviews. The results concluded in the feasibility of implementing the system as a method of construction of buildings resistant to earthquakes of great magnitude subject to strict monitoring of the parameters described in the relevant regulations for the country, however the information provided is of great importance for individuals and contractors in the construction area in Colombia, since the expert engineers in calculations have some contradictions as for the industrialized system, and this can be factor of incidences in the response to earthquakes of these buildings, it is for that reason that the information revealed is a novelty to take into account the types of systems that calculate them the same but really have many structural differences and this could be a key element in an earthquake of great magnitude.

Exergy, economic, and life-cycle assessment of orc system for waste heat recovery in a natural gas internal combustion engine

Valencia, Guillermo | 2020-01-01

In this article, an organic Rankine cycle (ORC) was integrated into a 2-MW natural gas engine to evaluate the possibility of generating electricity by recovering the engine’s exhaust heat. The operational and design variables with the greatest influence on the energy, economic, and environmental performance of the system were analyzed. Likewise, the components with greater exergy destruction were identified through the variety of different operating parameters. From the parametric results, it was found that the evaporation pressure has the greatest influence on the destruction of exergy. The highest fraction of exergy was obtained for the Shell and tube heat exchanger (ITC1) with 38% of the total exergy destruction of the system. It was also determined that the high value of the heat transfer area increases its acquisition costs and the levelized cost of energy (LCOE) of the thermal system. Therefore, these systems must have a turbine technology with an efficiency not exceeding 90% because, from this value, the LCOE of the system surpasses the LCOE of a gas turbine. Lastly, a life cycle analysis (LCA) was developed on the system operating under the selected organic working fluids. It was found that the component with the greatest environmental impact was the turbine, which reached a maximum value of 3013.65 Pts when the material was aluminum. Acetone was used as the organic working fluid.

Exhaust gas heat exchanger design based on the engine backpressure and heat rate criteria

Cárdenas-Gutiérrez, Javier Alfonso | 2020-10

The use of shell and tube heat exchangers for waste heat recovery has shown excellent results in increasing engine performance, as well as offering a large surface area for small volumes, ease of cleaning, good mechanical layout, and well-known design procedure. This article presents the modeling of the coupling circuit and thermo-fluid design of the heat exchangers in the thermal oil circuit in order to maximize the heat transfer of this equipment at the lowest pressure drop and acquisition cost, which is obtained with a smaller heat transfer area. The research results show the existence of optimal values for the studied system parameters, type of organic working fluid, type of heat exchangers, besides the size of the other system components, which are particular for the studied application. However, these results cannot be compared with the real projects already implemented in the industry due to their absence. It has been verified that the fluids that have showed the best performance in terms of thermal efficiency have been acetone and benzene, with an overall thermal efficiency of 17% and 15%, respectively.

Experimental and CFD characterization of the jacket vessel heat transfer process

Cárdenas-Gutiérrez, Javier Alfonso | 2020-10

Heat exchange processes are widely applicable in industry and research. The process of design and optimization of these types of devices is of particular interest, since they generate a high rate of exergy destruction. In this study, a correlation between the data presented by the OpenFOAM® software computer model of the assembly of a jacketed vessel heat exchanger has been made. The influence of the overall heat transfer coefficient on the temperature profile and the relationship between Reynolds number and the heat yielded by hot water have been studied. It has been concluded that the theoretical-experimental model has an analogy with the CFD one, which has showed an admissible error of 9.3% for different volumetric flows in relation to the overall heat transfer coefficient and temperature. Therefore, it shows a significant advantage in the use of the computational model to find a correlation with the experimental data. Additionally, the cost of experimentation can be reduced using computational tools.