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Search Results: 1 - 10 of 402291 matches for " M. Tapia "
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Separación Neumática de Finos desde Corrientes de Mineral Chancado
Tapia,Jaime M;
Información tecnológica , 2006, DOI: 10.4067/S0718-07642006000600023
Abstract: an alternative technique is presented for reducing the production of fines ( particles of less than 212 mm in size) during the crushing process applied to copper minerals. the proposed method included pneumatic separation of the fines from an ascending flow of air applied to artificially prepared samples of crushed mineral which were prepared containing various quantities of fines ranging from 10 to 25% by weight. laboratory tests verified separation of the fines from the samples using the proposed method. in static bed tests, separation of nearly 90% was obtained, starting with ratios of (u0/ut) = 2 (for a prepared sample containing 20% fines and surface air velocity of u0 = 100 cm/s). on the other hand, tests with a moving bed gave a separation near 75% for similar samples and working conditions. this behavior was repeated for all the test samples prepared. these results allowed validation of the alternative technique for the pneumatic separation of fines from currents of crushed minerals
Separación Neumática de Finos desde Corrientes de Mineral Chancado Pneumatic Separation of Fines from Currents of Crushed Minerals
Jaime M Tapia
Información Tecnológica , 2006,
Abstract: Se presenta una alternativa técnica para reducir la generación de finos (partículas de tama o inferior a 212 μm) en el proceso de chancado de mineral de cobre. La propuesta consiste en la separación neumática de los finos a través de la acción de un flujo ascendente de aire aplicado a muestras sintéticas de mineral chancado, preparadas con diferentes contenidos de finos (de 10 a 25% en peso). En pruebas de laboratorio se verificó la separación de los finos contenidos en las muestras a través de esta técnica. En pruebas en lecho estático se obtuvo una separación cercana al 90%, a partir de razones (U0/Ut) = 2 (para una muestra sintética con 20% de finos y velocidad superficial de aire U0 = 100 cm/s). Por su parte, pruebas en lecho móvil entregaron una separación cercana al 75%, para una muestra y condiciones similares. Este comportamiento se replicó para todas las muestras sintéticas ensayadas. Estos resultados permiten validar la alternativa técnica de separar en forma neumática las partículas finas desde corrientes de mineral chancado An alternative technique is presented for reducing the production of fines ( particles of less than 212 mm in size) during the crushing process applied to copper minerals. The proposed method included pneumatic separation of the fines from an ascending flow of air applied to artificially prepared samples of crushed mineral which were prepared containing various quantities of fines ranging from 10 to 25% by weight. Laboratory tests verified separation of the fines from the samples using the proposed method. In static bed tests, separation of nearly 90% was obtained, starting with ratios of (U0/Ut) = 2 (for a prepared sample containing 20% fines and surface air velocity of U0 = 100 cm/s). On the other hand, tests with a moving bed gave a separation near 75% for similar samples and working conditions. This behavior was repeated for all the test samples prepared. These results allowed validation of the alternative technique for the pneumatic separation of fines from currents of crushed minerals
THE STAR FORMATION REGION NGC 6334
M. Tapia,P. Persi
Revista mexicana de astronomía y astrofísica , 2009,
Abstract: The bright nebular complex NGC 6334 contains some of the most active sites of massive star formation known in our Galaxy. It is located at a distance from the Sun of 1.62 kpc and has a total mass of a few 105M . The physical characteristics of the active spots range widely, from well developed expanding HII regions to deeply embedded, still contracting, young objects detected only as millimeter sources, thus at their earliest observable stage of their evolution. The oldest optically visible round HII regions with central O-type stars are found in the southern parts, and the youngest along a molecular ridge. On the latter, no clear spatial evolutionary correlation is apparent.
Universal field equations for metric-affine theories of gravity
V. Tapia,M. Ujevic
Physics , 2006, DOI: 10.1088/0264-9381/15/11/028
Abstract: We show that almost all metric--affine theories of gravity yield Einstein equations with a non--null cosmological constant $\Lambda$. Under certain circumstances and for any dimension, it is also possible to incorporate a Weyl vector field $W_\mu$ and therefore the presence of an anisotropy. The viability of these field equations is discussed in view of recent astrophysical observations.
Young and very young stars in NGC 3372, the Carina Nebula
M. Tapia,M. Roth,P. Persi
Revista mexicana de astronomía y astrofísica , 2004,
Abstract:
EMBEDDED YOUNG STARS IN NORTHERN NGC 3372
M. Tapia,M. Roth,P. Persi
Revista mexicana de astronomía y astrofísica , 2011,
Abstract: Se presentan nuevas imágenes en el cercano infrarrojo obtenidas con PANIC montado en el telecopio Magallanes "Baade" del Observatorio Las Campanas. Estas fueron tomadas a través de filtros anchos JHKs y de filtros angostos centrados en las líneas Br en 2.17 m y H2 en 2.12 m. El estudio se complementó con imágenes del archivo del Satélite Spitzer con IRAC. Se presenta evidencia de la existencia de un cúmulo joven de radio r = 23'' embebido en Tr14-N4. Este contiene varias estrellas de baja y mediana masa y al menos una protoestrella de alta masa. Se presentan sus propiedades derivadas de la fotometría desde 1.2 hasta 11 m. Se encuentran varios nudos de emisión compacta en la línea de H2, lo que evidencia la existencia de al menos un flujo de masa, presumiblemente proveniente del núcleo del cúmulo. Se presentan también resultados recientes del monitoreo de dos jóvenes estrellas variables Car I-136 y 125, embebidas en la nube densa asociada con Car I.
Aplicación de una pauta dise?ada para evaluar informes académicos universitarios
Tapia,Mónica; Burdiles,Gina; Arancibia,Beatriz;
Revista signos , 2003, DOI: 10.4067/S0718-09342003005400009
Abstract: the students's affiliation to a university takes place when s/he demonstrates that s/he can be an autonomous reader and a competent writer of academic discourse. although one of the most required pieces of writing in this context is the report, university students usually present/display difficulties to face this task. on the other hand, it is a little frequent that teachers give precise and explicit directions to guide the writing process. the objective of this article is to present/display the results of the implementation of a guideline checklist created to evaluate the most relevant aspects that a university report must take into account. the sample corresponded to 17 reports produced by students in the speciality subjetcs of two majors from universidad católica de la santísima concepción. the guideline checklist consisted of 24 indicators, 9 dimensions and 4 quality categories. the results demonstrate the use of the textual reproduction of fragments from the sources, neglecting the information processing, required to create autonomous, intentional texts that (re)construct knowledge.
Estrés oxidativo, prooxidantes y enfermedad de Crohn
Tapia S,Alexis; Araya M.,Magdalena;
Revista médica de Chile , 2006, DOI: 10.4067/S0034-98872006000100014
Abstract: the frequency of crohn disease shows a significant increase in the last century. affected patients show a misbalance between production of free radicals and anti oxidant defenses. thus, one of the increasingly accepted htypotheses to explain the origin of this disease, is the oxidative stress that occurs in the intestinal mucosa. dietary factors including self administered vitamin and mineral supplemets may play a role, especially when they contain excessive amounts of iron and copper, known for their prooxidant capacities. unfortunately, little is known about how these metals may influence the antioxidant defenses in the intestinal mucosa. this article reviews the literature on the why and how these elements may act on individuals susceptible to develop crohm disease, including the evidence supporting the hypothesis that oxidative stress in the intestinal mucosa is an important pathogenetic factor
Estrés oxidativo, prooxidantes y enfermedad de Crohn Oxidative stress, prooxidants and Crohn disease
Alexis Tapia S,Magdalena Araya M.
Revista médica de Chile , 2006,
Abstract: The frequency of Crohn disease shows a significant increase in the last century. Affected patients show a misbalance between production of free radicals and anti oxidant defenses. Thus, one of the increasingly accepted htypotheses to explain the origin of this disease, is the oxidative stress that occurs in the intestinal mucosa. Dietary factors including self administered vitamin and mineral supplemets may play a role, especially when they contain excessive amounts of iron and copper, known for their prooxidant capacities. Unfortunately, little is known about how these metals may influence the antioxidant defenses in the intestinal mucosa. This article reviews the literature on the why and how these elements may act on individuals susceptible to develop Crohm disease, including the evidence supporting the hypothesis that oxidative stress in the intestinal mucosa is an important pathogenetic factor
La palatalización de las velares. Análisis acústico
Mónica Tapia-Ladino,Humberto Valdivieso
Onomázein : Revista de Lingüística, Filología y Traducción , 1997,
Abstract: Uno de los rasgos más característicos del espa ol de Chile es el alto grado de palatalización de las consonantes velares cuando van seguidas de yod o de vocal anterior. Este fenómeno articulatorio se manifiesta acústicamente como una elevación de la frecuencia de ruido de fricción en el caso de la áfona fricativa. Mediante un análisis acústico se ha medido la duración y la frecuencia del ruido en las realizaciones de /x/ extraídas de una muestra del habla de la televisión con el propósito de examinar en qué medida este rasgo aparece en esa variedad de habla. Las mismas mediciones se han efectuado en el habla de los locutores de la televisión espa ola con el fin de efectuar una comparación. (One of the most salient features of Chilean Spanish is the high degree of velar consonant palatalization when followed by yod or a frontal vowel. The acoustic correlate of this articulatory phenomenon is the frequency increase of friction noise in the case of the voiceless fricative. The realizations of /x/ in a sample of Chilean television speech have been measured acoustically, focusing on the duration and frequency noise. The aim was to find out to what extent palatalization appears in that speech variety. For comparative purposes, the same measures have been made in the speech of Spanish television.)
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