Examinando por Materia "Elasticity"
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Ítem Caracterización del mercado de exportación de café especial en Colombia : segmentación, tamaño y elasticidad(Universidad EAFIT, 2022) Velásquez Restrepo, Daniel; Pérez Restrepo, Camilo AlbertoCoffee is one of Colombia's leading agricultural export products and represents the livelihood of thousands of rural families, but the price trend has been downward since the end of the Coffee Agreement and the financial viability of production is frequently questioned. Faced with this scenario, the country has been entering the recent specialty coffee market as an alternative to improve the price through the production of a higher quality bean. Currently, there is no clarity in the country about the economic characteristics of this market nor an objective definition of specialty coffee that would allow this analysis to be carried out. Therefore, this paper focuses on determining a statistical price criterion and based on this, segmenting the Colombian green coffee export market between differentiated coffee and commercial coffee, seeking to understand its size and evolution in the last decade. The results of said exercise show that the segment of differentiated coffee is small compared to commercial coffee, reaching a 13.59% share for the year of maximum value. Although, there is a continuous growth of the segment in absolute values for all the years analyzed. Additionally, regressions were carried out that show a negative correlation between the increase in price and the decrease in tons exported for the general market. This is relevant for the expectations that a large coffee producer such as Colombia may set for this market.Ítem Determining optimal selling time of cattle: a stochastic dynamic programming application(Universidad EAFIT, 2015) Mejía Mejía, Susana; Ramírez Hassan, AndrésWorld’s meat market conditions have forced the beef sector to look for strategies to become competitive and researchers have proved that optimal replacement decisions are one of the most important factors that affect competitiveness -- The present paper formulates a model in a discrete stochastic dynamic programming framework which describes manager’s decision-making process combining both economic and biological variables and involving uncertainty on price fluctuations: investors can use the model to support their decisions of selling or keeping a fattening animal -- The methodology developed is very general and can be used in different regions under similar production conditions by calibrating the parameters and making the required changes according to local regulations -- The paper illustrates model’s conveniences with an empirical application based on a local Colombian market, proving that researchers were right when ranked the dynamic programming as an excellent modeling tool for evaluating livestock replacementÍtem Effect of the Phenological Stage in the Natural Rubber Latex Properties(Springer New York LLC, 2019-01-01) Zapata-Gallego N.T.; Álvarez-Láinez M.L.; Universidad EAFIT. Departamento de Ingeniería de Diseño; Ingeniería de Diseño (GRID)Natural Rubber Latex (NRL) from Hevea brasiliensis is a material studied because of their industrial applications. For its natural origin, it is possible to find rubber particles, proteins, phospholipids and ashes. These non-rubber content are responsible for the latex colloidal stability. H. brasiliensis tree goes through four stages during the year, changing its nutritional requirements and as a result the rubber yield and stability. Most studies have correlated latex characteristics and yield with tree age and clonal origin but none of them with phenological stages. The impact of the phenological stage on the material properties has not been completely identified yet. In this work, the influence of the clonal origin and the phenological stage with the material properties is studied. Thermal behavior, microstructural analysis, morphological study, colloidal stability and rheology are analyzed for FX3864, IAN710 and AIN873 clones during 1 year. NRL is an amorphous material but during the high-yield period, a melting point is observed. Flowering is the stage when phospholipids, protein and isoelectric point are higher. Phenological stages do not affect the rubber, but the main changes are in the non-rubber content. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.Ítem Estado del arte de la guadua como material alternativo para la construcción sostenible(Universidad EAFIT, 2011) Builes Hoyos, Tatiana; Giraldo Montoya, Carolina; Botero Botero, Luis FernandoÍtem Estimación de un modelo de demanda para la categoría de bebidas espirituosas por medio de un modelo de demanda casi ideal(2020) Millan Gil, Laura Tatiana; Cadavid Navas, Alejandro; Gómez Toro, CatalinaThis research is focused on proposing how the alcoholic beverage industry can use the different elasticities of the products as a fundamental element to the right decision making in the competitive strategy. It aims to validate how the own and competitors’ price changes of a brand in the market affect its demand under an almost ideal demand system. Currently, the prices are considered as key instruments to get growing results in the short and long term.Ítem Estudio del comportamiento de un material termoplástico durante el proceso de estiramiento(Universidad EAFIT, 2008) Restrepo Montoya, José Hernán; Ossa Henao, Édgar AlexánderÍtem Implementación de herramientas de apoyo en el proceso de decisión del Pricing y distribución comercial para los productos del activo bancario del segmento personas dentro de la banca minorista(Universidad EAFIT, 2023) Franco Amaya, Jair Fabian; Ardila Rodríguez, Jhon Sebastian; Rojas Ormaza, Brayan RicardoÍtem Influencia de la fibra de vidrio en las propiedades mecánicas de mezclas de concreto(Universidad EAFIT, 2013) Zapata Sierra, Jhon Anderson; Arango Córdoba, Samuel; Acevedo Jaramillo, Ana BeatrízEste proyecto de grado tuvo como objetivo principal determinar las propiedades mecánicas que obtiene el concreto al adicionarle fibra de vidrio tipo AR, esto se logró mediante una serie de ensayos de resistencia a la compresión, a la tensión y módulo de elasticidad, realizando un trabajo comparativo con una mezcla de referencia, dichos ensayos fueron realizados en el laboratorio Construlab Ltda. y el laboratorio de Suelos, Concretos y Pavimentos de la Universidad EAFIT -- Se buscó trabajar con una mezcla de referencia la cual permitiera que al adicionarle la fibra de vidrio lograra una trabajabilidad de la mezcla aceptable, y que a la vez obtuviera valores de resistencia a la compresión, tensión y modulo elasticidad de las mezclas más comerciales en el medio de la construcción -- Los porcentajes de fibra que se usó durante la fase experimental fue de 0.5%, 1%, 1.5%, 2% y 2.5% del peso total de la mezcla realizada -- También se realizó un estudio conceptual recopilando toda la información existente en cuanto a adiciones y aditivos utilizados en el concreto, estudiando específicamente la fibra de vidrio, sus propiedades y la influencia que esta tiene en el concreto -- Durante el proyecto de grado se logró concluir que la fibra de vidrio como adición a las mezclas de concreto aporta de manera positiva en cuanto a los tres parámetros estudiados adicionándole un 1% de fibra de vidrio a la mezcla, si se usa menos cantidad de fibra que la indicada no afecta en nada a ningún parámetro de los estudiados a la mezcla de referencia, pero si se usa en exceso ya empieza a afectar la mezcla en varios aspectos, principalmente en la cuestión de resistencia a la compresión, módulo de elasticidad y trabajabilidad, pero de cierto modo también aporta de manera positiva en tensión, por ende se buscó objetar una mezcla con porcentaje de adición de fibra de vidrio balanceada la cual aportara de manera positiva a los parámetros analizados, en cuanto a resistencia a compresión logro una ganancia casi nula del 3%, en cuanto a tensión se logró una ganancia importante del 11.66%, y en cuanto a módulo de elasticidad un aumento del 16 %, todos estos valores comparados con la mezcla de referenciaÍtem Material properties of mandibular cortical bone in the American alligator, Alligator mississippiensis(ELSEVIER SCIENCE INC, 2010-03-01) Zapata, Uriel; Metzger, Keith; Wang, Qian; Elsey, Ruth M.; Ross, Callum F.; Dechow, Paul C.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Bioingeniería GIB (CES – EAFIT)This study reports the elastic material properties of cortical bone in the mandible of juvenile Alligator mississippiensis obtained by using an ultrasonic wave technique. The elastic modulus, the shear modulus, and Poisson's ratio were measured on 42 cylindrical Alligator bone specimens obtained from the lingual and facial surfaces of 4 fresh Alligator mandibles. The data suggest that the elastic properties of alligator mandibular cortical bone are similar to those found in mammals and are orthotropic. The properties most resemble those found in the cortex of mammalian postcranial long bones where the bone is most stiff in one direction and much less stiff in the two remaining orthogonal directions. This is different from cortical bone found in the mandibles of humans and some monkeys, where the bone has greatest stiffness in one direction, much less stiffness in another direction, and an intermediate amount in the third orthogonal direction. This difference suggests a relationship between levels of orthotropy and bending stress. The comparability of these elastic moduli to those of other vertebrates suggest that the high bone strain magnitudes recorded from the alligator mandible in vivo are not attributable to a lower stiffness of alligator mandibular bone. © 2009 Elsevier Inc.Ítem Material properties of the skull layers of the primate parietal bone: A single-subject study(Public Library of Science, 2020-01-01) Zapata, U.; Wang, Q.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Bioingeniería GIB (CES – EAFIT)The outer cortical table of the parietal bone has been commonly used as a calvarial bone graft site for the craniofacial reconstruction. However, little is known about how removing the outer table may affect the function and structure of the inner table, and how the knowledge of the biomechanics and material properties of cortical bones will help the calvarial graft to better integrate into the biological and mechanical functions of its surrounding native tissues. In this study, it was hypothesized that there were significant differences in both density and material properties between inner and outer cortical plates in cranial bones. Twelve cylindrical specimens, including inner-outer layers, of cortical parietal bone of a female baboon were collected. Cortical thicknesses and densities were measured, and elastic properties were assessed using an ultrasonic technique. Results demonstrated remarkable difference in both thickness (t = 8.248, p .0.05) and density (t = 4.926, p.0.05) between inner and outer cortical paired samples. Orthotropic characteristics of the cortical plates were detected as well, these findings suggest that there are differences in biomechanical properties between two surfaces of cranial bones at both tissue and organ levels. How these differences are linked to the stress environments of the inner and outer cranial cortical layers awaits further studies. Further study will greatly enhance our ability to address questions derived from both morphological and craniofacial medicine fields about the development and biomechanics of craniofacial skeletons. © 2020 Zapata, Wang.Ítem Material properties of the skull layers of the primate parietal bone: A single-subject study(Public Library of Science, 2020-01-01) Zapata, U.; Wang, Q.; Zapata, U.; Wang, Q.; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de IngenieríaThe outer cortical table of the parietal bone has been commonly used as a calvarial bone graft site for the craniofacial reconstruction. However, little is known about how removing the outer table may affect the function and structure of the inner table, and how the knowledge of the biomechanics and material properties of cortical bones will help the calvarial graft to better integrate into the biological and mechanical functions of its surrounding native tissues. In this study, it was hypothesized that there were significant differences in both density and material properties between inner and outer cortical plates in cranial bones. Twelve cylindrical specimens, including inner-outer layers, of cortical parietal bone of a female baboon were collected. Cortical thicknesses and densities were measured, and elastic properties were assessed using an ultrasonic technique. Results demonstrated remarkable difference in both thickness (t = 8.248, p .0.05) and density (t = 4.926, p.0.05) between inner and outer cortical paired samples. Orthotropic characteristics of the cortical plates were detected as well, these findings suggest that there are differences in biomechanical properties between two surfaces of cranial bones at both tissue and organ levels. How these differences are linked to the stress environments of the inner and outer cranial cortical layers awaits further studies. Further study will greatly enhance our ability to address questions derived from both morphological and craniofacial medicine fields about the development and biomechanics of craniofacial skeletons. © 2020 Zapata, Wang.Ítem Mechanical properties study for new hypothetical crystalline phases of ReB2: A computational approach using density functional theory(Elsevier, 2016-09-01) Marín-Suárez, M.; Vélez, M.E.; David, J.; Arroyave-Franco, M.; Marín-Suárez, M.; Vélez, M.E.; David, J.; Arroyave-Franco, M.; Universidad EAFIT. Departamento de Ciencias; Lógica y ComputaciónRhenium diboride (ReB2) in its P6(3)/mmc crystalline structure, is widely known as a super-hard material, and has been studied many times using the Density Functional Theory (DFT) approach. In this work the same chemical composition was studied in three additional unreported hypothetical crystallographic phases by means of DFT with the hybrid functional approach, and the elastic constants of each phase were calculated. The elastic behavior of ReB2 was analyzed by means of elastic moduli calculations. Additionally, the velocities of the elastic waves of each phase were calculated, along with the Debye's temperatures, also elastic anisotropy is studied. Semi-empirical and empirical models of hardness were used to estimate qualitatively which phases are or are not hard. It has been determined that the elastic moduli of two out of the three hypothetical phases are desirable and the elastic waves move very slow (< 2 km/s) in one of them. These results and the analysis of the bond critical points (bcp) of each phase allow us to conclude that one of them is soft while the other two are hard. The synthesized phase of ReB(2)P6(3)/mmc was studied in order to compare and confirm the results. (C) 2016 Elsevier B.V. All rights reserved.Ítem Mechanical properties study for new hypothetical crystalline phases of ReB2: A computational approach using density functional theory(Elsevier, 2016-09-01) Marín-Suárez, M.; Vélez, M.E.; David, J.; Arroyave-Franco, M.; Universidad EAFIT. Departamento de Ciencias Básicas; Electromagnetismo Aplicado (Gema)Rhenium diboride (ReB2) in its P6(3)/mmc crystalline structure, is widely known as a super-hard material, and has been studied many times using the Density Functional Theory (DFT) approach. In this work the same chemical composition was studied in three additional unreported hypothetical crystallographic phases by means of DFT with the hybrid functional approach, and the elastic constants of each phase were calculated. The elastic behavior of ReB2 was analyzed by means of elastic moduli calculations. Additionally, the velocities of the elastic waves of each phase were calculated, along with the Debye's temperatures, also elastic anisotropy is studied. Semi-empirical and empirical models of hardness were used to estimate qualitatively which phases are or are not hard. It has been determined that the elastic moduli of two out of the three hypothetical phases are desirable and the elastic waves move very slow (< 2 km/s) in one of them. These results and the analysis of the bond critical points (bcp) of each phase allow us to conclude that one of them is soft while the other two are hard. The synthesized phase of ReB(2)P6(3)/mmc was studied in order to compare and confirm the results. (C) 2016 Elsevier B.V. All rights reserved.Ítem Numerical estimation of Carbonate properties using a digital rock physics workflow(2014) Osorno, M.; Uribe, D.; Saenger, E.H.; Madonna, C.; Steeb, H.; Ruíz, Ó.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAEDigital rock physics combines modern imaging with advanced numerical simulations to analyze the physical properties of rocks -- In this paper we suggest a special segmentation procedure which is applied to a carbonate rock from Switzerland -- Starting point is a CTscan of a specimen of Hauptmuschelkalk -- The first step applied to the raw image data is a nonlocal mean filter -- We then apply different thresholds to identify pores and solid phases -- Because we are aware of a nonneglectable amount of unresolved microporosity we also define intermediate phases -- Based on this segmentation determine porositydependent values for the pwave velocity and for the permeability -- The porosity measured in the laboratory is then used to compare our numerical data with experimental data -- We observe a good agreement -- Future work includes an analytic validation to the numerical results of the pwave velocity upper bound, employing different filters for the image segmentation and using data with higher resolutionÍtem Proyección de precios de energía eléctrica de mediano plazo en el mercado colombiano mediante la aplicación del índice de Lerner(Universidad EAFIT, 2016) Díez Restrepo, Iván Camilo; Blandón Díaz, Jaime AlbertoÍtem Reproducing Kernel Element Method for Galerkin Solution of Elastostatic Problems(Universidad EAFIT, 2012-12-01) J Juha, Mario; Universidad Autónoma del CaribeÍtem The role of volumetric power input in the growth, morphology, and production of a recombinant glycoprotein by Streptomyces lividans in shake flasks(ELSEVIER SCIENCE BV, 2014-09-15) Marin-Palacio, Luz D.; Gamboa-Suasnavart, Ramses A.; Valdez-Cruz, Norma A.; Servin-Gonzalez, Luis; Soledad Cordova-Aguilar, Ma.; Soto, Enrique; Kloeckner, Wolf; Buechs, Jochen; Trujillo-Roldan, Mauricio A.; Marin-Palacio, Luz D.; Gamboa-Suasnavart, Ramses A.; Valdez-Cruz, Norma A.; Servin-Gonzalez, Luis; Soledad Cordova-Aguilar, Ma.; Soto, Enrique; Kloeckner, Wolf; Buechs, Jochen; Trujillo-Roldan, Mauricio A.; Universidad EAFIT. Departamento de Ingeniería de Procesos; Procesos Ambientales (GIPAB)The impact of flask geometry on Streptomyces lividans growth and morphology, production and O-mannosylation of a recombinant O-glycoprotein (APA from Mycobacterium tuberculosis) was described and associated to the evolution of the volumetric power input (P/V) in three shake flask geometries. During the exponential growth, the highest P/V was found in baffled flasks (BF) with 0.51kW/m3, followed by coiled flasks (CF) with 0.44kW/m3 and normal Erlenmeyer flasks (NF) with 0.20kW/m3 (flasks volume of 250mL, filling with 50mL and agitated at 150rpm). During the stationary phase, P/V decreased 20% in BF and CF, but increased two times in NF, surely due to changes in mycelial morphology and its effects on rheology. Also, NF cultures were carried out at a filling volume and agitation of 15mL, 150rpm (15mL-NF), and 25mL, 168rpm (25mL-NF), in order to raise P/V closely to the values obtained in CF. However, different growth, morphology and recombinant protein productivity were obtained. These data indicate that P/V is not a definitive parameter that can determine bacteria growth and morphology, not even glycoprotein production. But it can be proposed that the oxygen transfer in the center of the pellets and hydromechanical stress might be the more relevant parameters than P/V. © 2014 Elsevier B.V.Ítem The role of volumetric power input in the growth, morphology, and production of a recombinant glycoprotein by Streptomyces lividans in shake flasks(ELSEVIER SCIENCE BV, 2014-09-15) Marin-Palacio, Luz D.; Gamboa-Suasnavart, Ramses A.; Valdez-Cruz, Norma A.; Servin-Gonzalez, Luis; Soledad Cordova-Aguilar, Ma.; Soto, Enrique; Kloeckner, Wolf; Buechs, Jochen; Trujillo-Roldan, Mauricio A.; Universidad EAFIT. Departamento de Ciencias; Ciencias Biológicas y Bioprocesos (CIBIOP)The impact of flask geometry on Streptomyces lividans growth and morphology, production and O-mannosylation of a recombinant O-glycoprotein (APA from Mycobacterium tuberculosis) was described and associated to the evolution of the volumetric power input (P/V) in three shake flask geometries. During the exponential growth, the highest P/V was found in baffled flasks (BF) with 0.51kW/m3, followed by coiled flasks (CF) with 0.44kW/m3 and normal Erlenmeyer flasks (NF) with 0.20kW/m3 (flasks volume of 250mL, filling with 50mL and agitated at 150rpm). During the stationary phase, P/V decreased 20% in BF and CF, but increased two times in NF, surely due to changes in mycelial morphology and its effects on rheology. Also, NF cultures were carried out at a filling volume and agitation of 15mL, 150rpm (15mL-NF), and 25mL, 168rpm (25mL-NF), in order to raise P/V closely to the values obtained in CF. However, different growth, morphology and recombinant protein productivity were obtained. These data indicate that P/V is not a definitive parameter that can determine bacteria growth and morphology, not even glycoprotein production. But it can be proposed that the oxygen transfer in the center of the pellets and hydromechanical stress might be the more relevant parameters than P/V. © 2014 Elsevier B.V.Ítem Solución viscosa a un sistema de elasticidad generalizado(Universidad EAFIT, 2012) Gómez Plata, Adrián Ricardo; Cerón Gómez, MillerÍtem A Spatial Analysis to Permanent Income as Deterrent of Homicides: the case of Medellin City(Universidad EAFIT, 2016-05-04) Urrego, Joaquin A.; Gómez Toro, Catalina; Velásquez, Hermilson; cgomezt1@eafit.edu.co; evelas@eafit.edu.coThis paper studies the relationship between permanent income and homicides, estimating an income-crime elasticity. We assume that this elasticity varies across geographical areas. We estimate different specifications of Spatial Panel Models using information of urban areas in Medellin (Colombia), areas known as communes. Spatial Models consider the importance of location and the type of neighbors of each commune. We simulate an intervention over permanent income in order to estimate the income elasticity for each commune and the average elasticity of income-crime on the city. We provide evidence about spatial dependence between the homicides per commune and their neighbors, and about a relationship between homicides and neighbor’s income. In our case of study, the average estimated impact of 1% increase in permanent income in a specific commune produces a decrease in the homicide rate on average in 0.39%. Finally, permanent income plays a crime deterrent role, but also this effect of income on crime varies across the city, showing that some areas are strategically located to this kind of intervention.