Diego F. Tirado, Diofanor Acevedo-Correa, P. M. Montero-Castillo
Una gran cantidad de productos son secados por diversas razones, tales como la preservacion, la reduccion de peso y el mejoramiento de su estabilidad. Sin embargo, los metodos tradicionales de secado de alimentos solidos no presentan productos de bajo costo y alta calidad de manera simultanea. A pesar de que existen metodos efectivos de deshidratacion de los alimentos como la liofilizacion, que preserva el sabor, color y las vitaminas, son tecnologias de poca accesibilidad, por lo cual se hacen necesarios procesos alternativos que sean eficientes y economicos. El objetivo de esta investigacion fue comparar la cinetica del secado de rebanadas de fruto del arbol del pan (Artocarpus communis) mediante la tecnica de Ventana Refractiva® (VR) con la de secado en bandeja. Para llegar a cabo este trabajo, se usaron rodajas de 1 y 2 mm de espesor. El secado con VR se realizo con temperatura del bano de agua a 92 °C; y el secado en bandeja a 62 °C y una velocidad del aire de 0,52 m/s. Durante el secado por la tecnica de VR, el contenido de humedad llega a niveles mas bajos que el secado en bandejas. De igual manera sucede con las muestras de 1 mm, las cuales, por tener menor diametro alcanzan niveles de humedad inferior que las muestras de 2 mm. Las mayores difusividades se obtuvieron durante el secado por VR en rodajas de 1 y 2 mm con coeficientes de 6,13 y 3,90*10-9 m2/s respectivamente.
{"title":"Secado de rodajas de fruto del árbol del pan mediante la técnica de Ventana Refractiva","authors":"Diego F. Tirado, Diofanor Acevedo-Correa, P. M. Montero-Castillo","doi":"10.22430/22565337.591","DOIUrl":"https://doi.org/10.22430/22565337.591","url":null,"abstract":"Una gran cantidad de productos son secados por diversas razones, tales como la preservacion, la reduccion de peso y el mejoramiento de su estabilidad. Sin embargo, los metodos tradicionales de secado de alimentos solidos no presentan productos de bajo costo y alta calidad de manera simultanea. A pesar de que existen metodos efectivos de deshidratacion de los alimentos como la liofilizacion, que preserva el sabor, color y las vitaminas, son tecnologias de poca accesibilidad, por lo cual se hacen necesarios procesos alternativos que sean eficientes y economicos. El objetivo de esta investigacion fue comparar la cinetica del secado de rebanadas de fruto del arbol del pan (Artocarpus communis) mediante la tecnica de Ventana Refractiva® (VR) con la de secado en bandeja. Para llegar a cabo este trabajo, se usaron rodajas de 1 y 2 mm de espesor. El secado con VR se realizo con temperatura del bano de agua a 92 °C; y el secado en bandeja a 62 °C y una velocidad del aire de 0,52 m/s. Durante el secado por la tecnica de VR, el contenido de humedad llega a niveles mas bajos que el secado en bandejas. De igual manera sucede con las muestras de 1 mm, las cuales, por tener menor diametro alcanzan niveles de humedad inferior que las muestras de 2 mm. Las mayores difusividades se obtuvieron durante el secado por VR en rodajas de 1 y 2 mm con coeficientes de 6,13 y 3,90*10-9 m2/s respectivamente.","PeriodicalId":30469,"journal":{"name":"TecnoLogicas","volume":"38 1","pages":"103-111"},"PeriodicalIF":0.0,"publicationDate":"2016-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68494115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Four thermal spray coatings were applied by oxy-fuel process onto ASTM A743 CA6NM (13Cr-4Ni) steel, namely: two Ni-rich alloys, a chromium oxide and a combined tungsten carbide/Ni-Cr particles coating. The microstructure and adhesive/cohesive strength of the coatings were studied and related to the surface preparation parameters (preheating temperature and surface roughness). The microstructures were studied by XRay diffraction (XRD), scanning electron (SEM) and light optical (LOM) microscopy and hardness was measured according to ASTM E384 standard. The adhesive/cohesive strength was measured according to ASTM C633 standard. The microstructure of the coatings showed porosity (8% for bond coatings and from 15 to 30% for ceramic coatings) within acceptable values for flame spraying Homogeneous coating thicknesses of circa 0.5 mm were obtained. Adhesive strength was among 10 to 19 MPa for most of coatings. The coating-substrate adhesive strength was satisfactory in most cases and significant variations (higher than 25%) in adhesive/cohesive strength were induced by changes in surface preparation parameters, especially in the case of WC/Co-Ni coating.
{"title":"Microestructura y resistencia adhesivo-cohesiva de recubrimientos de níquel, carburo de tungsteno y óxido de cromo aplicados por aspersión térmica","authors":"J. F. Santa-Marín, Alejandro Toro-Betancur","doi":"10.22430/22565337.592","DOIUrl":"https://doi.org/10.22430/22565337.592","url":null,"abstract":"Four thermal spray coatings were applied by oxy-fuel process onto ASTM A743 CA6NM (13Cr-4Ni) steel, namely: two Ni-rich alloys, a chromium oxide and a combined tungsten carbide/Ni-Cr particles coating. The microstructure and adhesive/cohesive strength of the coatings were studied and related to the surface preparation parameters (preheating temperature and surface roughness). The microstructures were studied by XRay diffraction (XRD), scanning electron (SEM) and light optical (LOM) microscopy and hardness was measured according to ASTM E384 standard. The adhesive/cohesive strength was measured according to ASTM C633 standard. The microstructure of the coatings showed porosity (8% for bond coatings and from 15 to 30% for ceramic coatings) within acceptable values for flame spraying Homogeneous coating thicknesses of circa 0.5 mm were obtained. Adhesive strength was among 10 to 19 MPa for most of coatings. The coating-substrate adhesive strength was satisfactory in most cases and significant variations (higher than 25%) in adhesive/cohesive strength were induced by changes in surface preparation parameters, especially in the case of WC/Co-Ni coating.","PeriodicalId":30469,"journal":{"name":"TecnoLogicas","volume":"19 1","pages":"27-40"},"PeriodicalIF":0.0,"publicationDate":"2016-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68494232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Germán A. Bacca-Bastidas, Iván Vásquez-Valencia, Julián Pérez-Ordóñez
This article aims to present the results obtained from the design, construction and characterization of a pneumatic flapper-nozzle amplifier, employed in the measurement of average surface roughness. In the construction of the sensor, low cost materials were used and most pieces were obtained by machining. The data acquisition was performed through PC, using an Arduino interface board. The nonlinear mathematical model of the sensor is based on equations of perfect gas flow through an orifice and the continuity law for a control volume. The characterization of physical parameters obtained through laboratory techniques based on the transient response of the gas pressure in the pressurization and depressurization processes of constant volume chambers, using computational tools for adjusting experimental curves. The validation of the model was based on the specifications of transient response that presents a dynamic system for a step input. For the measurement of the roughness, the mathematical model of average roughness, Ra, was used, and the measured data by the sensor were obtained in sandpapers from P1000 to P2000 size, with reference for validation values of average roughness indicated by the FEPA standard.
{"title":"Diseño, construcción y caracterización de sistema neumático para la medición de rugosidad","authors":"Germán A. Bacca-Bastidas, Iván Vásquez-Valencia, Julián Pérez-Ordóñez","doi":"10.22430/22565337.186","DOIUrl":"https://doi.org/10.22430/22565337.186","url":null,"abstract":"This article aims to present the results obtained from the design, construction and characterization of a pneumatic flapper-nozzle amplifier, employed in the measurement of average surface roughness. In the construction of the sensor, low cost materials were used and most pieces were obtained by machining. The data acquisition was performed through PC, using an Arduino interface board. The nonlinear mathematical model of the sensor is based on equations of perfect gas flow through an orifice and the continuity law for a control volume. The characterization of physical parameters obtained through laboratory techniques based on the transient response of the gas pressure in the pressurization and depressurization processes of constant volume chambers, using computational tools for adjusting experimental curves. The validation of the model was based on the specifications of transient response that presents a dynamic system for a step input. For the measurement of the roughness, the mathematical model of average roughness, Ra, was used, and the measured data by the sensor were obtained in sandpapers from P1000 to P2000 size, with reference for validation values of average roughness indicated by the FEPA standard.","PeriodicalId":30469,"journal":{"name":"TecnoLogicas","volume":"18 1","pages":"45-55"},"PeriodicalIF":0.0,"publicationDate":"2015-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68483477","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Marilse Araque-Pabón, G. Peña-Rodríguez, Fabio Vargas-Galvis
Se presentan los resultados de la evaluacion de la resistencia a la flexion y al desgaste por abrasion profunda de baldosas ceramicas de arcilla roja con y sin recubrimientos de Al2O3, depositados mediante proyeccion termica oxiacetilenica. Las baldosas ceramicas fueron elaboradas por prensado uniaxial a 30 bares con posterior tratamiento de sinterizacion a 1100°C, a partir polvos atomizados de arcilla roja. Por su parte, para la elaboracion de los recubrimientos se utilizaron polvos de α-Al2O3 de referencia comercial Sulzer Metco® 105SFP, los cuales fueron depositados obteniendo tres espesores diferentes. La resistencia a la flexion y a la abrasion profunda se evaluo de acuerdo con las normas ISO 10545-4 e ISO 10545-6 respectivamente. Los resultados obtenidos indican que la abrasion profunda de las baldosas ceramicas disminuyo al incrementarse el espesor de la capa de alumina depositada. Por otra parte, los recubrimientos de alumina incrementaron entre un 5 y un 49% la resistencia mecanica a la flexion de las baldosas de arcilla de acuerdo con el espesor y la adherencia de la capa al sustrato. Los resultados obtenidos contribuiran al desarrollo de productos ceramicos con valor agregado, para ser usados en diversas aplicaciones tecnologicas.
{"title":"Desempeño mecánico y tribológico de baldosas cerámicas de arcilla roja recubiertas por proyección térmica a partir de alúmina","authors":"Marilse Araque-Pabón, G. Peña-Rodríguez, Fabio Vargas-Galvis","doi":"10.22430/22565337.194","DOIUrl":"https://doi.org/10.22430/22565337.194","url":null,"abstract":"Se presentan los resultados de la evaluacion de la resistencia a la flexion y al desgaste por abrasion profunda de baldosas ceramicas de arcilla roja con y sin recubrimientos de Al2O3, depositados mediante proyeccion termica oxiacetilenica. Las baldosas ceramicas fueron elaboradas por prensado uniaxial a 30 bares con posterior tratamiento de sinterizacion a 1100°C, a partir polvos atomizados de arcilla roja. Por su parte, para la elaboracion de los recubrimientos se utilizaron polvos de α-Al2O3 de referencia comercial Sulzer Metco® 105SFP, los cuales fueron depositados obteniendo tres espesores diferentes. La resistencia a la flexion y a la abrasion profunda se evaluo de acuerdo con las normas ISO 10545-4 e ISO 10545-6 respectivamente. Los resultados obtenidos indican que la abrasion profunda de las baldosas ceramicas disminuyo al incrementarse el espesor de la capa de alumina depositada. Por otra parte, los recubrimientos de alumina incrementaron entre un 5 y un 49% la resistencia mecanica a la flexion de las baldosas de arcilla de acuerdo con el espesor y la adherencia de la capa al sustrato. Los resultados obtenidos contribuiran al desarrollo de productos ceramicos con valor agregado, para ser usados en diversas aplicaciones tecnologicas.","PeriodicalId":30469,"journal":{"name":"TecnoLogicas","volume":"1 1","pages":"125-135"},"PeriodicalIF":0.0,"publicationDate":"2015-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68484355","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Andrés M. Vélez-Pereira, Eliana L. Vergara-Vásquez, William D. Barraza-Coronell, Diana C. Agudelo-Yepes
La radiacion solar global se establece como una variable meteorologica necesaria para en el entendimiento de los procesos bioquimicos del ambiente; su medicion es compleja y requiere un alto costo de instalacion, operacion y mantenimiento. Su estimacion se puede realizar mediante formulas empiricas basadas fundamentalmente en su geo-posicionamiento, no obstante la precision de los resultados obtenidos no es adecuada para el entendimiento de los procesos evaluados. El objetivo del presente trabajo fue establecer un modelo estadistico de correlacion para estimar la radiacion solar global a partir de los datos meteorologicos alternos. La informacion meteorologica fue suministrada por el Instituto de Hidrologia, Meteorologia y Estudios Ambientales de Colombia, que proporciono la medicion de radiacion solar, temperatura, humedad relativa y horas de sol. Se plantearon regresiones simples entre las variables y la radiacion solar; y regresiones multiples entre las posibles combinaciones de las variables y la radiacion solar. Se evidencio una buena correlacion estadistica entre las variables radiacion solar, temperatura y humedad relativa, y poca relacion con las horas de sol; siendo la humedad relativa la que guarda una mayor correlacion y por tanto influencia en el modelo. Los modelos multivariados (R2 promedio 11,91%) presentaron mejor ajuste comparado con los modelos simples (R2 promedio 5,66%). El mejor modelo lo establece la regresion multiple en la que se incluyen todas las variables (R2 de 13,75%), no siendo este el modelo mas simple para su estimacion.
{"title":"Evaluación de un modelo estadístico para estimar la radiación solar en Magdalena, Colombia","authors":"Andrés M. Vélez-Pereira, Eliana L. Vergara-Vásquez, William D. Barraza-Coronell, Diana C. Agudelo-Yepes","doi":"10.22430/22565337.196","DOIUrl":"https://doi.org/10.22430/22565337.196","url":null,"abstract":"La radiacion solar global se establece como una variable meteorologica necesaria para en el entendimiento de los procesos bioquimicos del ambiente; su medicion es compleja y requiere un alto costo de instalacion, operacion y mantenimiento. Su estimacion se puede realizar mediante formulas empiricas basadas fundamentalmente en su geo-posicionamiento, no obstante la precision de los resultados obtenidos no es adecuada para el entendimiento de los procesos evaluados. El objetivo del presente trabajo fue establecer un modelo estadistico de correlacion para estimar la radiacion solar global a partir de los datos meteorologicos alternos. La informacion meteorologica fue suministrada por el Instituto de Hidrologia, Meteorologia y Estudios Ambientales de Colombia, que proporciono la medicion de radiacion solar, temperatura, humedad relativa y horas de sol. Se plantearon regresiones simples entre las variables y la radiacion solar; y regresiones multiples entre las posibles combinaciones de las variables y la radiacion solar. Se evidencio una buena correlacion estadistica entre las variables radiacion solar, temperatura y humedad relativa, y poca relacion con las horas de sol; siendo la humedad relativa la que guarda una mayor correlacion y por tanto influencia en el modelo. Los modelos multivariados (R2 promedio 11,91%) presentaron mejor ajuste comparado con los modelos simples (R2 promedio 5,66%). El mejor modelo lo establece la regresion multiple en la que se incluyen todas las variables (R2 de 13,75%), no siendo este el modelo mas simple para su estimacion.","PeriodicalId":30469,"journal":{"name":"TecnoLogicas","volume":"18 1","pages":"35-44"},"PeriodicalIF":0.0,"publicationDate":"2015-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68484689","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Héctor F. Bermúdez-Orozco, Evelio Astaiza-Hoyos, Luis Freddy Muñoz-Sanabria
This paper presents one of the results of research conducted to study the changes in the impedance input and radiation pattern parameters of the antenna systems, specifically linear arrays of microstrip dipoles are used; it is chosen as a parameter study the radiation pattern, the input impedance parameter will be presented in another publication. For their study, the system is modeled using numerical techniques with the help of the method of moments, in the conformation of the mesh array is used basis function given by Rao-Wilton and Glisson. The model is simulated with the Matlab® tool, the radiation pattern is determined for a dipole type patch and an array of these; the parasitic elements (dipoles) are located at different distances from the original array dipole and calculates the radiation pattern again, which are compared to those originally found. Finally, the results are presented and the advantage of these studies for handling radiation pattern in radiant systems is evident. Additionally, the presence of an element of symmetry is evident, this situation allows a considerable decrease the number of simulations, since the effect of the parasitic elements located on one side of the array of dipoles is similar to the effect that occurs when the parasitic elements are located on the opposite side.
{"title":"Cambios del patrón de radiación en arreglos lineales de dipolos de microcinta a 2,4 GHz en presencia de elementos parásitos","authors":"Héctor F. Bermúdez-Orozco, Evelio Astaiza-Hoyos, Luis Freddy Muñoz-Sanabria","doi":"10.22430/22565337.185","DOIUrl":"https://doi.org/10.22430/22565337.185","url":null,"abstract":"This paper presents one of the results of research conducted to study the changes in the impedance input and radiation pattern parameters of the antenna systems, specifically linear arrays of microstrip dipoles are used; it is chosen as a parameter study the radiation pattern, the input impedance parameter will be presented in another publication. For their study, the system is modeled using numerical techniques with the help of the method of moments, in the conformation of the mesh array is used basis function given by Rao-Wilton and Glisson. The model is simulated with the Matlab® tool, the radiation pattern is determined for a dipole type patch and an array of these; the parasitic elements (dipoles) are located at different distances from the original array dipole and calculates the radiation pattern again, which are compared to those originally found. Finally, the results are presented and the advantage of these studies for handling radiation pattern in radiant systems is evident. Additionally, the presence of an element of symmetry is evident, this situation allows a considerable decrease the number of simulations, since the effect of the parasitic elements located on one side of the array of dipoles is similar to the effect that occurs when the parasitic elements are located on the opposite side.","PeriodicalId":30469,"journal":{"name":"TecnoLogicas","volume":"18 1","pages":"21-34"},"PeriodicalIF":0.0,"publicationDate":"2015-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68483925","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Liliana M. Usuga-Manco, Alejandro Lopez-Valdivieso, M. Bustamante-Rúa
In this research three methodologies to convert the hydrophilic surface of kaolinite into a hydrophobic surface are proposed, this condition is required to recover this mineral by means of froth flotation. Taking into account the anisotropy, zeta potential and complex surface electrical properties of the kaolinite, three surface chemical treatments based on the interacting and absorption of anionic collectors onto the mineral surface, causing an increase in the contact angle and thus increased hydrophobicity of kaolinite were applied. The methodologies proposed were interactions of kaolinite particles with: sodium dodecyl sulfate solutions with concentration 1x10-3M, 1x10-4M, 1x10-5M; sodium dodecyl sulfate solutions 1x10-3M, 1x10-4M, 1x10-5M with further interaction with kerosene solutions 127000 ppm; and oleic acid solutions 1x10-3M, 1x10-4M, 1x10-5M, each one with a five minutes of interaction. The experimental results obtained by zeta potential and contact angle of the kaolinite before and after applying chemical treatments indicate that larger the chain length of the collector and its concentration, bigger the contact angle and so, more hydrophobic the surface (edge or face). In order to optimize, control and understand this solid-liquid interaction phenomenon is suggested to find out about the hydrophobization mechanism of kaolinite with oleic acid and its percentage of hydrophobization.
{"title":"Estudio de la hidrofobicidad de la caolinita de La Unión, Antioquia","authors":"Liliana M. Usuga-Manco, Alejandro Lopez-Valdivieso, M. Bustamante-Rúa","doi":"10.22430/22565337.184","DOIUrl":"https://doi.org/10.22430/22565337.184","url":null,"abstract":"In this research three methodologies to convert the hydrophilic surface of kaolinite into a hydrophobic surface are proposed, this condition is required to recover this mineral by means of froth flotation. Taking into account the anisotropy, zeta potential and complex surface electrical properties of the kaolinite, three surface chemical treatments based on the interacting and absorption of anionic collectors onto the mineral surface, causing an increase in the contact angle and thus increased hydrophobicity of kaolinite were applied. The methodologies proposed were interactions of kaolinite particles with: sodium dodecyl sulfate solutions with concentration 1x10-3M, 1x10-4M, 1x10-5M; sodium dodecyl sulfate solutions 1x10-3M, 1x10-4M, 1x10-5M with further interaction with kerosene solutions 127000 ppm; and oleic acid solutions 1x10-3M, 1x10-4M, 1x10-5M, each one with a five minutes of interaction. The experimental results obtained by zeta potential and contact angle of the kaolinite before and after applying chemical treatments indicate that larger the chain length of the collector and its concentration, bigger the contact angle and so, more hydrophobic the surface (edge or face). In order to optimize, control and understand this solid-liquid interaction phenomenon is suggested to find out about the hydrophobization mechanism of kaolinite with oleic acid and its percentage of hydrophobization.","PeriodicalId":30469,"journal":{"name":"TecnoLogicas","volume":"18 1","pages":"71-81"},"PeriodicalIF":0.0,"publicationDate":"2015-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68483865","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To estimate the effective friction angle of soil from in situ test is a complicated job, due to high rates of strain existing in this kind of tests, which tend to be too invasive and disturb the vicinities of test depth, even the sample that eventually is taken at the site. Likewise, the most of the correlations found in the current bibliography to obtain the effective friction angle using field tests, have been developed for soils from different regions. For that reason when are implemented on tropical soils present high scatter, to compare the field parameter values with real results obtained at the lab. This research aims to use in situ tests define through of analysis of different correlations, which fits adequately to the specific conditions of the piedmont soils of Bogota. For the present study will be utilized data from SPT (widely used in Colombia) and SPT-T (never before conducted in the country), carried out considering the appropriated norms to each test, taking in account to SPT-T, doesn’t exist local standard governing such tests. The correlations for field procedures of the tests implemented were for effective confining and energy transference of the SPT hammer, since the state-of-the-art mentions it as the most affect the reliability of the final results. The final results show the tendency of the methodologies used to obtain the correlation, in relation with the real value of effective friction angle from of lab tests.
{"title":"Análisis de las correlaciones existentes del ángulo de fricción efectivo para suelos del piedemonte oriental de Bogotá usando ensayos in situ","authors":"July E. Carmona-Álvarez, J. C. Ruge-Cárdenas","doi":"10.22430/22565337.191","DOIUrl":"https://doi.org/10.22430/22565337.191","url":null,"abstract":"To estimate the effective friction angle of soil from in situ test is a complicated job, due to high rates of strain existing in this kind of tests, which tend to be too invasive and disturb the vicinities of test depth, even the sample that eventually is taken at the site. Likewise, the most of the correlations found in the current bibliography to obtain the effective friction angle using field tests, have been developed for soils from different regions. For that reason when are implemented on tropical soils present high scatter, to compare the field parameter values with real results obtained at the lab. This research aims to use in situ tests define through of analysis of different correlations, which fits adequately to the specific conditions of the piedmont soils of Bogota. For the present study will be utilized data from SPT (widely used in Colombia) and SPT-T (never before conducted in the country), carried out considering the appropriated norms to each test, taking in account to SPT-T, doesn’t exist local standard governing such tests. The correlations for field procedures of the tests implemented were for effective confining and energy transference of the SPT hammer, since the state-of-the-art mentions it as the most affect the reliability of the final results. The final results show the tendency of the methodologies used to obtain the correlation, in relation with the real value of effective friction angle from of lab tests.","PeriodicalId":30469,"journal":{"name":"TecnoLogicas","volume":"18 1","pages":"93-104"},"PeriodicalIF":0.0,"publicationDate":"2015-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68484035","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Daniela Soto-Martínez, Carolina Parra-Velásquez, M. E. López-Gómez, Carlos F. Vásquez-Jiménez, Fabio Vargas-Galvis
A coated system consisting of a ceramic substrate and a coating of a copper alloy was developed in order to provide electrically conductive properties to specific surface of the substrate. The coatings were elaborated by oxy-fuel thermal spraying processes. The best way to prepare the surface of the substrate was previously determined to achieve a sufficient adherence of copper alloy particles on the ceramic substrate. In order to manufacture the coatings an Eutectic CastolinTM 21071 powder was used, the oxy-fuel flames were produced from two different volumetric acetylene-oxygen ratios (1:1.15 and 1:2.5) obtaining a reducing and oxidizing flame respectively. The effect of surface preparation of the substrate, the coating thickness and the energy of the flame on the structure and coating adhesion were evaluated. It was found that the coatings obtained using a reducing flame presented lower adhesion values to the ceramic substrate and a higher level of porosity in its structure, while those made using an oxidizing flame presented greater adhesion and an homogenous structure (low porosity). Finally, a very low adhesion values were obtained on the non-prepared substrates with both flames.
{"title":"Elaboración de recubrimientos base cobre sobre un sustrato de porcelana mediante proyección térmica con llama oxiacetilénica","authors":"Daniela Soto-Martínez, Carolina Parra-Velásquez, M. E. López-Gómez, Carlos F. Vásquez-Jiménez, Fabio Vargas-Galvis","doi":"10.22430/22565337.190","DOIUrl":"https://doi.org/10.22430/22565337.190","url":null,"abstract":"A coated system consisting of a ceramic substrate and a coating of a copper alloy was developed in order to provide electrically conductive properties to specific surface of the substrate. The coatings were elaborated by oxy-fuel thermal spraying processes. The best way to prepare the surface of the substrate was previously determined to achieve a sufficient adherence of copper alloy particles on the ceramic substrate. In order to manufacture the coatings an Eutectic CastolinTM 21071 powder was used, the oxy-fuel flames were produced from two different volumetric acetylene-oxygen ratios (1:1.15 and 1:2.5) obtaining a reducing and oxidizing flame respectively. The effect of surface preparation of the substrate, the coating thickness and the energy of the flame on the structure and coating adhesion were evaluated. It was found that the coatings obtained using a reducing flame presented lower adhesion values to the ceramic substrate and a higher level of porosity in its structure, while those made using an oxidizing flame presented greater adhesion and an homogenous structure (low porosity). Finally, a very low adhesion values were obtained on the non-prepared substrates with both flames.","PeriodicalId":30469,"journal":{"name":"TecnoLogicas","volume":"18 1","pages":"83-91"},"PeriodicalIF":0.0,"publicationDate":"2015-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68483894","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
John E. Candelo-Becerra, H. E. Hernández-Riaño, Alcides R. Santander-Mercado
Electric power losses have a significant impact on the total costs of distribution networks. The use of renewable energy sources is a major alternative to improve power losses and costs, although other important issues are also enhanced such as voltage magnitudes and network congestion. However, determining the best location and size of renewable energy generators can be sometimes a challenging task due to a large number of possible combinations in the search space. Furthermore, the multiobjective functions increase the complexity of the problem and metaheuristics are preferred to find solutions in a relatively short time. This paper evaluates the performance of the cuckoo search (CS), harmony search (HS), and bat-inspired (BA) algorithms for the location and size of renewable distributed generation (RDG) in radial distribution networks using a multiobjective function defined as minimizing the energy losses and the RDG costs. The metaheuristic algorithms were programmed in Matlab and tested using the 33-node radial distribution network. The three algorithms obtained similar results for the two objectives evaluated, finding points close to the best solutions in the Pareto front. Comparisons showed that the CS obtained the minimum results for most points evaluated, but the BA and the HS were close to the best solution.
{"title":"Comparación de algoritmos multiobjetivo inspirados en búsqueda armónica, búsqueda cuco y murciélagos para la ubicación de generación distribuida renovable","authors":"John E. Candelo-Becerra, H. E. Hernández-Riaño, Alcides R. Santander-Mercado","doi":"10.22430/22565337.192","DOIUrl":"https://doi.org/10.22430/22565337.192","url":null,"abstract":"Electric power losses have a significant impact on the total costs of distribution networks. The use of renewable energy sources is a major alternative to improve power losses and costs, although other important issues are also enhanced such as voltage magnitudes and network congestion. However, determining the best location and size of renewable energy generators can be sometimes a challenging task due to a large number of possible combinations in the search space. Furthermore, the multiobjective functions increase the complexity of the problem and metaheuristics are preferred to find solutions in a relatively short time. This paper evaluates the performance of the cuckoo search (CS), harmony search (HS), and bat-inspired (BA) algorithms for the location and size of renewable distributed generation (RDG) in radial distribution networks using a multiobjective function defined as minimizing the energy losses and the RDG costs. The metaheuristic algorithms were programmed in Matlab and tested using the 33-node radial distribution network. The three algorithms obtained similar results for the two objectives evaluated, finding points close to the best solutions in the Pareto front. Comparisons showed that the CS obtained the minimum results for most points evaluated, but the BA and the HS were close to the best solution.","PeriodicalId":30469,"journal":{"name":"TecnoLogicas","volume":"18 1","pages":"105-116"},"PeriodicalIF":0.0,"publicationDate":"2015-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68484166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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