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Search Results: 1 - 10 of 6730 matches for " Diana; Giraldo "
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Distorsiones de la longitud por aplicaciones conformes y convexas
Diana C. Giraldo
Matemáticas : Ense?anza Universitaria , 2011,
Abstract: We derive a sharp estimate for the arclength of the image of the circle |z| = r under a convex univalent mapping. Our methods are different from those used by Keogh in [4].
La terminología archivística en Colombia: investigación documental y lexicométrica
Sierra Escobar,Luis Fernando; Giraldo,Diana Carolina;
Revista Interamericana de Bibliotecología , 2010,
Abstract: this paper presents the results derived from the documentary analysis carried out on the publications and normative texts of the colombian archivistics from 1989 to 2008. using a descriptive and documentary approach, a qualitative research was carried out on the bibliographic production and work of the national general archive, the archive of bogotá, the university of caldas, the university of quindío, the university of la salle and the archivistic norms in force in colombia. the objective was to study the terms with higher and lower frequency of occurrence, the distribution of items per publication, the total number of terms placed in 21 letters of the alphabet and the words with the highest indexes of occurrence by master unit. finally, stress was made on the importance of lexicometrical and terminological studies for the colombian archivistics and the main problems underlying the lexicon: ambiguity, polysemy, indiscriminate use of terms coming from foreign languages and the creation of neologisms that violate morphosyntactic patterns.
Performance of Ag-TiO2 Photocatalysts towards the Photocatalytic Disinfection of Water under Interior-Lighting and Solar-Simulated Light Irradiations
Camilo A. Castro,Adriana Jurado,Diana Sissa,Sonia A. Giraldo
International Journal of Photoenergy , 2012, DOI: 10.1155/2012/261045
Abstract: This paper reports the characterization and photoactivity of Ag-TiO2 materials using different amounts of silver during the hydrothermal synthesis. Photocatalysts were characterized by means of TEM, XPS, XRD, DRS, and N2 sorption isotherms to determine the textural properties. The photocatalyst's configuration was observed to be as anatase-brookite mixed phase particles with Ag partially oxidized aggregates on the TiO2 surface, which increased visible light absorption of the material. Moreover, photoproduction of singlet oxygen was followed by EPR analysis under visible light irradiations following the formation of TEMPOL. Such photoproduction was totally decreased by using the singlet oxygen scavenger DABCO. Photocatalysts were tested towards the photocatalytic disinfection of water suing a solar light simulator and an interior-light irradiation setup. Results evidenced an increase in the photooxidative effect of TiO2, while dark processes evidenced that part of the inactivation process is due to the Ag-TiO2 surface bactericidal effect and possible lixiviated Ag
Programación de Sistemas de Producción Híbridos, Para inventario/Bajo pedido, mediante un Proceso Analítico Jerárquico de Ordenación Grupal (GAHPO)
Escobar,Pamela; Giraldo,Jaime A; Cárdenas,Diana M;
Información tecnológica , 2012, DOI: 10.4067/S0718-07642012000500005
Abstract: this article presents a case study of a new production scheduling methodology applied on a manufacturing facility located on manizales, colombia, which combines make to stock (mts) and make to order (mto) environments. this implies to respond, using limited resources, to different, and sometimes opposite objectives, with negative impact on the service level. the proposed methodology uses group analytic hierarchy process ordering (gahpo) to develop a dispatching rule combining three priority criteria, that when it is compared with other three simple rules, through a discrete event simulation model, presents better performance in most of the selected measures of interest. the study allows concluding that for companies which operate under hybrid environments it is possible to reach equilibrium between market satisfaction and the utilization of available resources.
ANALISIS METODOLóGICO PARA LA MODELACIóN DE LA SEGURIDAD ALIMENTARIA A NIVEL NACIONAL
GIRALDO,DIANA P; BETANCUR,MANUEL J; ARANGO,SANTIAGO;
Biotecnología en el Sector Agropecuario y Agroindustrial , 2010,
Abstract: the scientific and politic community has had increasing concerns for strategic understanding and intervention of the food security problem, especially since the 70's food crisis. different methodological strategies have been used to foresight, to forecast and evaluate policies to support the process of decision-making in the public sector. this paper examines a series of methodologies used to study the food security problem at a national level. thereafter, we discuss the potential use of complementary methodologies, mainly system dynamics, as a simulation tool that provides insight on the causal relationships of the critical variables and allows the analysis of different scenarios of intervention in favor of effective decision making
Relación entre la entalpía de inmersión de monolitos de carbon activado y parametros texturales
Vargas, Diana P.;Gutiérrez, Liliana Giraldo;Moreno, Juan Carlos;
Química Nova , 2011, DOI: 10.1590/S0100-40422011000200005
Abstract: in this study, disc and honeycomb-shaped activated carbon monoliths were obtained using as a precursor coconut shell, without the use of any binder. textural characterization was performed by adsorption of n2 at 77 k and immersion calorimetry into benzene. the experimental results showed that the activation with zinc chloride produces a wide development of micropores, yielding micropore volumes between 0,38 and 0,79 cm3 g-1, apparent bet surface area between 725 and 1523 m2 g-1 and immersion enthalpy between 73,5 and 164,2 j g-1.were made comparisons between textural parameters and energy characteristics.
RELACIóN ENTRE PARáMETROS TEXTURALES Y ENERGéTICOS DE MONOLITOS DE CARBóN ACTIVADO A PARTIR DE CASCARA DE COCO
Vargas,Diana Paola; Giraldo,Liliana; Moreno,Juan C.;
Revista Colombiana de Química , 2009,
Abstract: structural characteristics and the energetic parameters of five monoliths of activated carbon were compared. the samples were obtained from coconut shells by means of chemical activation using different concentrations of phosphoric acid. the samples are characterized by means of physical adsorption of n2 at 77k, co2 at 273k, and immersion calorimetry in benzene. from the data obtained the volumes ofmicropore, mesopore, narrow microporosity and energy parameters of inmersion enthalpy were calculated. also were calculated, k of the langmuir model and characteristic energies, eo, of the dubinin-radushkevich model. the experimental results show that the activation with phosphoric acid develops microporosity, giving a micropore volume between 0,36 and 0,45 cm3g-1, area bet between 975 and 1320 m2g-1 and immersion enthalpy between 112,9 and 147,7 jg-1.it was found that for higher bet area, there is a greater immersion enthalpy in benzene, lower characteristic energy and smaller value of k.
ENTALPIA DE INMERSIóN DE MONOLITOS DE CARBóN ACTIVADO EN SOLVENTE APOLAR
Vargas,Diana P.; Giraldo Gutiérrez,Liliana; Moreno,Juan Carlos;
Revista Colombiana de Química , 2010,
Abstract: this work presents the results obtained from immersion calorimetry in benzene on activated carbon monoliths disc and honeycomb type that were obtained from coconut shell using chemical activation with zinc chloride at different concentrations. the structures were characterized by adsorption n2 at 77 k. the immersion enthalpies are between 73.5 and 164.2 jg-1. using immersion enthalpy data the accessible area was calculated and compared with the area obtained by n2 adsorption at 77k. a good correlation was found. in all the samples was observed an increase in the immersion enthalpy into benzene with the surface area. in addition there was a decrease in the energy characteristic with increasing pore volume.
El gas metano en la producción ganadera y alternativas para medir sus emisiones y aminorar su impacto a nivel ambiental y productivo
Carmona,Juan C; Bolívar,Diana M; Giraldo,Luis A;
Revista Colombiana de Ciencias Pecuarias , 2005,
Abstract: the ruminants are great contributors to the global heating and deterioration of the ozone layer, by the liberation of high amounts of gases to the atmosphere, among them, the carbon dioxide gas and the methane. the methane produced in rumen is generated mainly by fermentative processes of the food that enters to rumen. the main biotic factor at level of rumen in the methane production are the metanogenic anaerobic bacteria. these bacterias use different substrates for the methane production, but the main ones are the h2 and the co2. the elimination of these gases, mainly of the h2 implies the removal of a factor implied in the stability of ph ruminal being this essential for an optimal fermentation. but at the same way this methane production is considered like a loss of potentially usable energy. the effects of the metanogenic bacteria are employees mainly of the present substrates in the diet and of the interactions with other populations. interventions in the feeding offered to the animals, oriented towards optimizing the process of ruminal fermentation, repel generally in an improvement of the productive and reproductive parameters, had, among other aspects, to one better use of the energy. in addition, the diminution of the emissions to the atmosphere receives great importance in the protection of the environment. the diverse evidences show that the rate of methane emission by ruminal fermentation, is related to the characteristics physical-chemistries of the diet, which affect the level of consumption and the frequency of feeding. by this the subnutrition contributes to increase the methane emissions. the possibility of limiting the methane emissions by the cattle in tropical production systems, provides economic and environmental benefits. a reduction option consists of the substitution of conventional technologies by new concomitants alternatives with a suitable production and minimums environmental effects. within these alternatives of potential use in trop
El gas metano en la producción ganadera y alternativas para medir sus emisiones y aminorar su impacto a nivel ambiental y productivo The gas methane in the cattle production and alternative to measure its emissions and to lessen its impact at environmental and productive level
Juan C Carmona,Diana M Bolívar,Luis A Giraldo
Revista Colombiana de Ciencias Pecuarias , 2005,
Abstract: Los rumiantes son grandes contribuyentes al calentamiento global y deterioro de la capa de ozono, por la liberación de altas cantidades de gases a la atmósfera, entre ellos, el gas carbónico y el metano. El metano producido se genera principalmente por los procesos fermentativos del alimento que ingresa al rumen. El principal factor biótico a nivel del rumen en la producción de metano son las bacterias anaerobias metanógenas. Estas bacterias utilizan diferentes sustratos para la producción de metano, pero los principales son el H2 y el CO2. La eliminación de estos gases, principalmente del H2 implican la remoción de un factor implicado en la estabilidad del pH ruminal siendo este esencial para una óptima fermentación. Pero a la par se considera la producción de metano como una pérdida de energía potencialmente utilizable. Los efectos de las bacterias metanógenas son dependientes principalmente de los sustratos presentes en la dieta y de las interacciones con otras poblaciones. Intervenciones en la alimentación ofrecida a los animales, orientadas hacia optimizar el proceso de fermentación ruminal, generalmente repercuten en una mejora de los parámetros productivos y reproductivos, debido, entre otros aspectos, a una mejor utilización de la energía. Además, la disminución de las emisiones a la atmósfera cobra gran importancia en la protección del medio ambiente. Diversas evidencias muestran que la tasa de emisión de metano por fermentación ruminal, está relacionada con las características físico-químicas de la dieta, las cuales afectan el nivel de consumo y la frecuencia de alimentación. Por esto una subnutrición contribuye a incrementar las emisiones de metano. La posibilidad de limitar las emisiones de metano por el ganado en sistemas de producción tropical, provee beneficios económicos y medioambientales. Una opción de reducción consiste en la sustitución de tecnologías convencionales por nuevas alternativas concomitantes con una adecuada producción y mínimos efectos medioambientales. Dentro de estas alternativas de potencial uso en trópico está el manejo de pasturas, tendiente hacia mejorar su calidad. Una alternativa de amplio potencial y que hasta el momento ha tomado fuerza por sus múltiples beneficios son los sistemas silvopastoriles, pero poco se ha investigado su efecto sobre la producción de metano ruminal. Para la determinación de emisiones y la eficiencia de las alternativas implementadas, se debe recurrir a metodologías apropiadas que permitan extrapolar los resultados a las condiciones reales in vivo. Dentro de estas alternativas, el sistema
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