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Search Results: 1 - 10 of 304554 matches for " F. G.;Boschi "
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The 8th ICGG International Conference on Gas Geochemistry Preface: Fluids and tectonics
E. Boschi,F. Italiano,G. Martinelli
Annals of Geophysics , 2007, DOI: 10.4401/ag-4434
Abstract: The 8th International Conference on Gas Geochemistry provided the opportunity for scientists from different countries to meet each other, exchange ideas on the state of the art in gas geochemistry, and discuss advance in fluid geochemistry. The 8th ICGG meeting focused on three main geologic environments currently interacting with the human life: volcanoes, earthquakes and hydrocarbons. Ninety-four presentations gave participants chance to cover a variety of important research topics on gas geochemistry in geosciences including: gas migration in terrestrial and marine environments, Earth degassing and its relation to seismicity, volcanic eruptions, rare gases and application of isotope techniques, measurement and analytical techniques.
Consumo de gás natural na indústria de revestimentos ceramicos brasileira
Alves, H. J.;Melchíades, F. G.;Boschi, A. O.;
Ceramica , 2008, DOI: 10.1590/S0366-69132008000300009
Abstract: the natural gas is the main source of thermic energy generation used by ceramic covering industries around the world and it is also one of the itens which has the biggest weight over the finished product. in this work, it is presented a survey of the consumption of natural gas done in a factory of the productive pole of santa gertrudes-sp, which processes its products through a dry way, so that it was possible to determine the specific consumption of each consumer equipment, and also identify the "energetic necks" presented by the same.
Spray-dried Powder Granulometry: Influence on the Porous Microstructure of Polished Porcelain Tile
Alves, H. J.,Melchiades, F. G.,Boschi, A. O.
Boletín de la Sociedad Espa?ola de Cerámica y Vidrio , 2010,
Abstract: The low porosity of porcelain tile is the result of strict control of the material’s processing conditions (milling of raw materials, compaction and sintering) and the characteristics of the raw materials used in its formulation (formation of liquid phases). Sealed pores remaining after the manufacturing process are revealed at the surface after polishing and are the main factor responsible for staining the product. The porous microstructure of the sintered material depends on the characteristics of the porous microstructure of the green compact and on how the densification process evolves during sintering. The present work evaluated how the size distribution of spray-dried granules acts upon the porous microstructure of green compacts and of polished porcelain tile. The results revealed that minor adjustments in the granulometric distribution curve can reduce the visibility of stains on the polished surface, thus improving this property. La baja porosidad de los revestimientos porcelánicos, es el resultado del estricto control que se ejerce sobre los distintos parámetros que condicionan el procesamiento de los materiales ( molienda de la materias primas, compactación y sinterización) y de las características de las materias primas empleadas en su formulación (formación de fases líquidas). Los poros cerrados que se generan durante la fabricación, y que se abren en la superficie durante el proceso de pulido, son los principales responsables de las manchas que aparecen en la superficie del material. La porosidad microestructural de los materiales sinterizados está condicionada por la porosidad microstrucutural de la pieza en verde y por la evolución del proceso de densificación durante la sinterización. E l trabajo presente evalúa la influencia de la distribución granulométrica del granulado procedente del atomizador sobre la porosidad granulométrica de las piezas en verde y de la pieza ya pulida. Los resultados revelan como peque os ajustes en la curva de distribución granulométrica, pueden reducir la visibilidad de las manchas en la superficie pulida, mejorando así sus propiedades.
Porcelain tiles by the dry route
Melchiades, F. G.,Daros, M. T.,Boschi, A. O.
Boletín de la Sociedad Espa?ola de Cerámica y Vidrio , 2010,
Abstract: In Brazil, the second largest tile producer of the world, at present, 70% of the tiles are produced by the dry route. One of the main reasons that lead to this development is the fact that the dry route uses approximately 30% less thermal energy them the traditional wet route. The increasing world concern with the environment and the recognition of the central role played by the water also has pointed towards privileging dry processes. In this context the objective of the present work is to study the feasibility of producing high quality porcelain tiles by the dry route. A brief comparison of the dry and wet route, in standard conditions industrially used today to produce tiles that are not porcelain tiles, shows that there are two major differences: the particle sizes obtained by the wet route are usually considerably finer and the capability of mixing the different minerals, the intimacy of the mixture, is also usually better in the wet route. The present work studied the relative importance of these differences and looked for raw materials and operational conditions that would result in better performance and glazed porcelain tiles of good quality. En Brasil, en este momento segundo productor mundial, el 70% de los pavimentos cerámicos se obtiene por vía seca. Una de las razones fundamentales se debe a que esta vía supone un consumo energético inferior, en un 30%, a la via húmeda tradicional. La creciente preocupación mundial sobre los problemas medioambientales y el reconocimiento del papel central que juega el agua en este proceso han favorecido el desarrollo de la vía seca. En este contexto, el objetivo del presente trabajo es estudiar la viabilidad de la producción de pavimentos porcelánicos de alta calidad por vía seca. Una breve comparación entre ambas vías, en las condiciones standard de producción vigentes para producciones que no son de porcelánico, indican que existen dos diferencias substanciales; el tama o de partícula, utilizado en la vía húmeda es considerablemente mas fino, y la capacidad de mezclado entre los diferentes minerales que integran la composición es normalmente tambien mejor en la vía húmeda. El trabajos analiza la importancia relativa de ambos factores y estudia las materias primas y condiciones de proceso que podrían conducir a la obtención de pavimentos esmaltados de buena calidad.
Um método simples de caracteriza??o de argilominerais por difra??o de raios X
Albers, A. P. F.;Melchiades, F. G.;Machado, R.;Baldo, J. B.;Boschi, A. O.;
Ceramica , 2002, DOI: 10.1590/S0366-69132002000100008
Abstract: the x-ray diffraction technique has been widely used for the determination of crystalline phases in ceramic materials. the large content and high degree of orientation of quartz in clays pose a problem to the identification and characterization of the remaining phases. a simple and reliable method for the determination of clay minerals in clay materials, based on the sedimentation principle, is presented.
Efeito das propriedades dos esmaltes e engobes sobre a curvatura de revestimentos ceramicos
Dal Bó, M.;Melchiades, F. G.;Boschi, A. O.;Hotza, D.;
Ceramica , 2012, DOI: 10.1590/S0366-69132012000100019
Abstract: the interaction between support-glaze and support-engobe were studied separately regarding the central curvature of ceramic tiles. were formulated two glazes samples and four engobes samples, these were applied on a particular type of ceramic support with classification in the group b-iib, by norma abnt nbr 13.818/1997 - iso 13006. some characteristics were measured as "thermal expansion coefficient" and "shrinkage difference between support-engobe". a method was suggested d for evaluation of interaction between support-engobes and support-glazes. the results showed that, for interaction support-glazes the superposition of dilatometric curves method is well implemented; for interaction support-engobe, a statistical test was conducted with factorial design 22, indicating that the variable "shrinkage difference between support-engobe" is the variable significant to describe the central curvature of ceramic tiles.
Gres porcelánico esmaltado producido por vía seca: materias primas fundentes
Melchiades, F. G.,dos Santos, L. R.,Nastri, S.,Boschi, A. O.
Boletín de la Sociedad Espa?ola de Cerámica y Vidrio , 2012, DOI: 10.3989/cyv.192012
Abstract: Fluxing agents are particularly important in porcelain tile compositions because this type of ceramic tile requires high volumes of vitreous phases during firing to eliminate open porosity. The volume and viscosity of the vitreous phases formed during firing control the densification process and thus determine the firing temperature and pyroplastic deformation. The fluxing agents commonly employed in porcelain tile compositions are feldspars, phyllites (used in Brazil) and nephelines. These raw materials are water-insoluble, which makes them particularly suitable for compositions of traditional porcelain tile produced by the wet route. However, a large group of water-soluble raw materials also have a good potential to act as fluxing agents and could be used in dry route processes. In this context, the purpose of this work was to determine the fluxing potential of water-soluble or partially water-soluble raw materials in a porcelain tile composition. The effectiveness of several borates, i.e., colemanite, ulexite, hydroboracite, as well as sodium carbonate, was tested in a comparative study. The results of this study indicate that small additions of these fluxing agents suffice to greatly reduce the firing temperature without causing high pyroplastic deformation of the bodies. The best results were obtained in compositions containing hydroboracite. This finding is especially relevant for the creation of alternative compositions of porcelain tiles produced by the dry route. Dry route processing is currently the focus of a great deal of interest due to environmental and economic issues. Los agentes fundentes tienen una especial importancia en las composiciones de gres porcelánico, ya que este tipo de baldosa cerámica requiere altos volúmenes de fases vítreas durante el proceso de cocción para eliminar la porosidad abierta. El volumen y la viscosidad de las fases vítreas que se forman durante la cocción controlan el proceso de densificación y, por consiguiente, determinan la temperatura de cocción y la deformación piroplástica. Los agentes fundentes que se usan habitualmente en las composiciones de gres porcelánico son: feldespatos, filitas (usadas en Brasil) y nefelinas. Estas materias primas no son solubles al agua, lo que las hace particularmente adecuadas para las composiciones de gres porcelánico tradicional producido por vía húmeda. Sin embargo, existe un gran grupo de materias primas solubles que también tienen un gran potencial como fundentes y que podrían utilizarse en los procesos de vía seca. En este contexto, el objetivo de este trabajo ha sido d
Global permanent deformations triggered by the Sumatra earthquake
E. Boschi,E. Casarotti,R. Devoti,D. Melini,A. Piersanti,G. Pietrantonio,F. Riguzzi
Physics , 2005,
Abstract: The giant Sumatra-Andaman earthquake of December 26 2004 caused permanent deformations effects in a region of previously never observed extension. The GPS data from the world wide network of permanent IGS sites show significant coseismic displacements in an area exceeding 107 km^2. The effects of the permanent residual deformation field could be detected as far as Australia, the Phillipines and Japanese archipelagos, and, on the West, as far as the indian continent. The synthetic simulations of the coseismic displacement field obtained by means of a spherical model support the hypothesis that a considerable amount of energy has been released aseismically.
Ab initio analysis of the x-ray absorption spectrum of the myoglobin-carbon monoxide complex: Structure and vibrations
G. Veronesi,C. Degli Esposti Boschi,L. Ferrari,G. Venturoli,F. Boscherini,F. D. Vila,J. J. Rehr
Quantitative Biology , 2010, DOI: 10.1103/PhysRevB.82.020101
Abstract: We present a comparison between Fe K-edge x-ray absorption spectra of carbonmonoxy-myoglobin and its simulation based on density-functional theory determination of the structure and vibrations and spectral simulation with multiple-scattering theory. An excellent comparison is obtained for the main part of the molecular structure without any structural fitting parameters. The geometry of the CO ligand is reliably determined using a synergic approach to data analysis. The methodology underlying this approach is expected to be especially useful in similar situations in which high-resolution data for structure and vibrations are available.
Gruneisen's gamma function for liquid iron at the E a r t h 's outer core conditions
E. BOSCHI,F. MULARGIA
Annals of Geophysics , 1977, DOI: 10.4401/ag-4819
Abstract: SUMMARY. - WE derive the Gruneisen's gamma as a function of temperature and pressure for liquid iron at the temperature and pressures of the Earth's outer core taking into account the anharmonic and electronic contributions in a self-consistent way. We obtain numerical values definetely different from those generally quoted in the geophysical literature, but in agreement with recent experimental determinations.
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