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Search Results: 1 - 10 of 209069 matches for " Elkin L. López "
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Analytical Approximation to the Dynamics of a Binary Stars System with Time Depending Mass Variation  [PDF]
Gustavo V. López, Elkin L. López
Journal of Applied Mathematics and Physics (JAMP) , 2018, DOI: 10.4236/jamp.2018.63053
Abstract: We study the classical dynamics of binary stars when there is an interchange of mass between them. Assuming that one of the stars is more massive than others, the dynamics of the lighter one is analyzed as a function of its time depending mass variation. Within our approximations and models for mass transference, we obtain a general result which establishes that if the lightest star looses mass, its period increases. If the lightest star wins mass, its period decreases.
La salud como motivación para la práctica de actividad física en personas adultas
MARTíNEZ LóPEZ,ELKIN;
Iatreia , 2003,
Abstract: five hundred persons who started a program of physical activity were interviewed in order to determine the main motivations to become active. answers were classified into several categories and reported in regard to gender. cultural and technical knowledge that support the different factors are enuntiated. beauty was the main motivation for getting involved in physical fitness; relaxation, health and pleasure were also mentioned. fortunately when a person does exercise all the physical and mental benefits are included, no matter which the original intention was.
Sistemas de lógica difusa en el proceso de secado de café en lecho fluidizado
López Fontal,Elkin Mauricio;
Ingeniería e Investigación , 2005,
Abstract: the present investigation deals with a system for coffee bean drying on a fluidised bed. a prototype was used in which coffee beans were dried using several drying temperatures. the results showed 6 to 8 hour drying periods. the coffee beans presented uniform final humidity content and the product presented good sensory characteristics. complementing the foregoing and considering this process? degree of uncertainty, fuzzy logic systems were used for establishing some possible preliminary control strategies for drying coffee beans on a fluidised bed related to establishing the point of fluidisation, controlling surface air speed and using air temperature greater than 50oc at the start of the process.
Secado de café en lecho fluidizado
López Fontal,Elkin Mauricio;
Ingeniería e Investigación , 2006,
Abstract: all coffee is harvested as cherry grains which are then crushed and extracted traditionally or by applying the becolsub method. once the coffee parchment obtained has been washed, it is naturally or mechanically dried. static dryers are the most used mechanical dryers, generally producing lack of uniformity in the grain?s final humidity content which must range from 10% to 12% b.h. drying by fluidization was used in the present research work; this turns a solid particle bed into a suspended and expanded mass, possessing many of the properties of a liquid. a 5,000 g capacity prototype was designed and constructed in which coffee was dried at three air drying temperatures: 42°c, 46°c and 49°c; drying time lasted 6 to 8 hours. good uniformity in final grain humidity content was obtained, differences being less than 0.86%. as well as the grain test, a control cup test was used, finding that the product presented good organoleptic qualities.
Extracción de aceite de café
López Fontal,Elkin Mauricio;
Ingeniería e Investigación , 2007,
Abstract: the present work describes oil being extracted from toasted coffee by the extrusion method; two products are obtained from this process: coffee oil and pulp. toasted coffee was used which has a high amount of sensorial compounds. it should be noted that a significant criterion in evaluating the quality of coffee lies in its aroma. when extracting oil from coffee, a significant part of toasted coffee?s aromatic content leaves with it, varying according to the extraction method. a fixed oil having a high volatile load is thus obtained, presenting favourable sensory characteristics. the pulp was physically and chemically analysed to show its benefit and particular properties and, according to the results so obtained, it is a product having potential usefulness.
Extracción de aceite de café Extracting oil from coffee
López Fontal Elkin Mauricio
Ingeniería e Investigación , 2007,
Abstract: En el presente trabajo se realiza la extracción de aceite de café mediante el método de extrusión. En dicho proceso se obtienen dos productos: el aceite de café y la torta. Para tal propósito se utilizó café tostado, el cual se caracteriza por poseer una elevada cantidad de compuestos odoríferos; es importante saber que un criterio significativo en la valoración de la calidad del café, es su aroma. Al extraer el aceite, una parte significativa del contenido aromático del café tostado, que varía según el método de extracción usado, sale con él. Es asI como se obtiene un aceite filo con una alta carga volátil, el cual presenta características organolépticas favorables. Al segundo producto que se obtiene, se le realizó análisis físico-químico en aras de mostrar sus bondades y propiedades particulares, y de acuerdo a los resultados obtenidos, es un producto que presenta un amplio potencial de utilización. The present work describes oil being extracted from toasted coffee by the extrusion method; two products are obtained from this process: coffee oil and pulp. Toasted coffee was used which has a high amount of sensorial compounds. It should be noted that a significant criterion in evaluating the quality of coffee lies in its aroma. When extracting oil from coffee, a significant part of toasted coffee’s aromatic content leaves with it, varying according to the extraction method. A fixed oil having a high volatile load is thus obtained, presenting favourable sensory characteristics. The pulp was physically and chemically analysed to show its benefit and particular properties and, according to the results so obtained, it is a product having potential usefulness.
Sistemas de lógica difusa en el proceso de secado de café en lecho fluidizado Fuzzy logic systems applied to fluidise bed coffee drying
López Fontal Elkin Mauricio
Ingeniería e Investigación , 2005,
Abstract: En el presente trabalo de investigación se experimenta con un sistema de secado de granos en lecho fluidizado. Se utiliza un prototipo en el cual se seca café utilizando varias temperaturas del aire de secado (López, 2002). Los resultados obtenidos muestran que el tiempo de secado varIa entre 6 a 8 horas, el contenido de humedad final del grano presenta uniformidad y en prueba de tasa se obtiene un producto con caracterIsticas organolépticas de buena calidad. Como complemento a lo anterior y teniendo en cuenta el grado de incertidumbre de dicho proceso, median- te sistemas de lógica difusa se plantean en forma preliminar algunas posibles estrategias de control y automatización que presenta el proceso de secado de café en lecho fluidizado, relacionadas con: establecer el punto de fluidización de los granos hümedos, control de la velocidad superficial del aire, y usar al inicio del proceso de secado una temperatura de aire mayor de 50°C . The present investigation deals with a system for coffee bean drying on a fluidised bed. A prototype was used in which coffee beans were dried using several drying temperatures. The results showed 6 to 8 hour drying periods. The coffee beans presented uniform final humidity content and the product presented good sensory characteristics. Complementing the foregoing and considering this process’ degree of uncertainty, fuzzy logic systems were used for establishing some possible preliminary control strategies for drying coffee beans on a fluidised bed related to establishing the point of fluidisation, controlling surface air speed and using air temperature greater than 50°C at the start of the process.
Secado de café en lecho fluidizado Coffee parchment in fluidisation
López Fontal Elkin Mauricio
Ingeniería e Investigación , 2006,
Abstract: Todo el café se cosecha en grano cereza, el cual se beneficia en forma tradicional o aplicando el método Becolsub o de beneficio ecológico. Una vez lavado el café pergamino obtenido, se seca en forma natural o mecánicamente. Los secadores mecánicos más utilizados son de tipo estático, en los cuales generalmente se presentan problemas de desuniformidad en el contenido de humedad final del grano, la cual debe oscilar entre 10 y 12% b.h. En el presente trabalo de investigación se empleó el sistema de secado mediante fluidización, el cual convierte un lecho de partIculas sólidas en una masa suspendida y expandida que posee muchas de las propiedades de un lIquido. Se diseno y construyó un prototipo de 5.000 g de capacidad, en el cual se secó café balo tres condiciones de temperatura del aire de secado: 42, 46 y 49°C. El tiempo de secado varió de 6 a 8 horas. Se obtuvo una buena uniformidad en el contenido de humedad final del grano, con diferencias menores a 0.86%. Además al grano se le hizo prueba de taza, obteniéndose que el producto presenta caracterIsticas organolépticas de buena calidad. All coffee is harvested as cherry grains which are then crushed and extracted traditionally or by applying the Becolsub method. Once the coffee parchment obtained has been washed, it is naturally or mechanically dried. Static dryers are the most used mechanical dryers, generally producing lack of uniformity in the grain’s final humidity content which must range from 10% to 12% b.h. Drying by fluidization was used in the present research work; this turns a solid particle bed into a suspended and expanded mass, possessing many of the properties of a liquid. A 5,000 g capacity prototype was designed and constructed in which coffee was dried at three air drying temperatures: 42°C, 46°C and 49°C; drying time lasted 6 to 8 hours. Good uniformity in final grain humidity content was obtained, differences being less than 0.86%. As well as the grain test, a control cup test was used, finding that the product presented good organoleptic qualities.
Metarhizium anisopliae y Trichoderma viride controlan colonias de Atta cephalotes en campo mejor que un insecticida químico Metarhizium anisopliae and Trichoderma viride control colonies of Atta cephalotes in field better than a chemical insecticide
López Arismendy Elkin,Orduz Peralta Sergio
Revista Colombiana de Biotecnología , 2002,
Abstract: Las hormigas cortadoras de hojas Atta cephalotes son una plaga economicamente importante en la agricultura. Estas hormigas utilizan el material cortado para cultivar un hongo del cual se alimentan. En este estudio se aplicaron cebos basados en el hongo entorno patógeno Metarhizium anisopliae cepa M-137, Trichoderma uiride cepa T-26 antagonista del hongo simbionte de A. Cephalotes, y una combinación de ambos hongos, para el control de colonias de A. cephalotes en campo. Además, se compare la actividad insecticida de los cebos con hongos con el producto químico Pirimifos Metil, aplicado con insufladora. Las hormigas no detectaron los hongos formulados en forma de cebo, de manera que los cargaron hasta el interior de los nidos sin generar conductas de defensa. La mortalidad de los nidos tratados con los cebos estuvo por encima del 80%, mientras que el tratamiento con Pirimifos Metil solo alcanzo la muerte del 60% de los hormigueros. Además, después de una semana de la aplicación de los distintos tratamientos, se observaron cambios de comportamiento en los insectos, que se reflejaron principalmente en la ausencia de forrajeo. En conclusión, el hongo M. anisopliae fue efectivo para controlar colonias de A. Cephaloies, y su potencia fue superior a la del producto químico Pirimifos Metil. The leaf-cutting ant Atta cephalotes is an economically important pest in agriculture. These ants use the material they cut to cultivate a fungus from which they fed. In this study, baits prepared with the entomopathogenic fungus Metarhizium anisopliae strain M-137, Trichoderma viride strain T-26, antagonist of the symbiont fungus of A. cephaloies, and a combination of both fungi were applied in order to control A. cephalotes colonies under field conditions. In addition, the insecticide activity of the baits was compared to a chemical product, Pirimifos Metil, which was applied with an air pump. The ants did not detect the fungal agents contained in the baits, and introduced then into their nests without awakening defensive behaviors. The mortality of the bait-treated nests was higher than 80% while the treatment with Pirimifos Metil was effective in only 60% of the nests. Additionally, a week after the application of these treatments, changes in the insects' behavior were observed, reflected mainly in the absence of foraging activity. In conclusion, M. anisopliae was effective in controlling A. cephalotes colonies, and superior to the chemical product Pirimifos Metil.
Control de la garrapata Boophilus microplus con Metarhizium anisopliae, estudios de laboratorio y campo
LóPEZ,ELKIN; LóPEZ,GUSTAVO; ORDUZ,SERGIO;
Revista Colombiana de Entomología , 2009,
Abstract: the biocontrol potential of eight strains of metarhizium anisopliae was evaluated for the cattle tick boophilus microplus under laboratory and field conditions. the strain 137bm caused the highest effect on the reproductive capacity of the tick, decreasing tick oviposition by 90 and 96% when adult ticks were treated in vitro with 1x108 and 1x109 conidia/ ml. it also reduced egg viability by more than 98% in the same doses. in the field trials it was possible to reduce tick infestation by 75% in holstein x cebú cows when m. anisopliae 137bm was applied at a concentration of 1x108 conidias/ ml. also, the fecundity of the ticks coming from cows treated with m. anisopliae was three times lower than that of the control group. on the other hand, strain 137bm applied to the meadow at a concentration of 5x1012 conidia/ha concentration caused a decrease in the larval tick population close to 86% one week after an application with conidia of m. anisopliae.
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