Geotechnical Performance of a Tunnel in Soft Ground

The analysis of a tunnel section excavated through soft ground is presented. The tunnel construction was monitored and its behavior is compared with results obtained by a numerical simulation. The field instrumentation and the geotechnical properties of the site are presented and the modeling of the soil behavior using Lade\u27s model discussed

A sedimentação carbonífera na Bacia do Buçaco (Centro de Portugal)

Os aspectos gerais das ocorrências do Carbónico continental em Portugal são descritos por Ribeiro et al. (1979), Teixeira & Gonçalves (1980) e Teixeira (1981). A revisão da cronoestratigrafia da flora fóssil destas formações e uma síntese da evolução tectónica de cada uma das bacias podem ser encontradas no volume editado por Sousa & Oliveira em 1983, dedicado ao Carbónico de Portugal. (...

Levantamento da composição da matovegetação e florística nativa em quintais diversificados.

O solo é componente chave no processo de produção de alimentos e fibras. A produtividade de quintais agroflorestais está diretamente relacionada com a manutenção e/ou construção da fertilidade do solo

EVALUATION OF PRESSURE DROP IN FLOW OVER FIXED POROUS BED

Many studies are conducted about the dynamics of fluids in porous media, which generates a number of factors and problems are solved. In particular the phenomenon of pressure drop in flows on fixed bed, although fairly well in the form Ergun’s equation, still has certain inconsistencies with regard to the types of materials to be used in the packaging of the beds. The objective of this work is to study this phenomenon using some experiments reported in the literature to determine the pressure drop in fixed bed consisting of porous particles of açaí seed. Experimental studies were conducted to predict, and take into account the losses resulting from friction and inertia that showed strong dependence on velocity. The method of using the particular friction factor prediction as a way to replace the usual calculation and measurement of pressure drop. The analysis in the wind tunnel was made from different sizes of bed, with a decrease in arithmetic progressions corresponding to half the value of the diameter of the tube used in the test. Several bands of Reynolds number were also employed in order to be able to visualize how the phenomenon behaves on various tracks. For such a survey was necessary some parameters such as açaí seeds diameters, seed weight and volume occupied by the bed; these parameters are of vital importance in Ergun equation, because an important aspect of the phenomenon is the porosity which enters as a foundation in the theory of flow fixed bed. At the end of the study was found the divergence in big bands of the Reynolds number of the correlation between experimental data and the Ergun equation

Simulation of the velocity field in compound channel flow using different closure models

1st European IAHR Congress,6-4 May, Edinburg, ScotlandIn this study a comparison of three turbulence closure models (two isotropic and one anisotropic) with experimental data is performed. The interaction between the main channel (MC) flow and the floodplain (FP) generates a complex flow structure. A shallow mixing layer develops between the MC flow and the slower FP flow generating a high horizontal shear layer, streamwise and vertical vortices, momentum transfer and other phenomena, related to velocity retardation and acceleration. This phenomenon dissipates part of the kinetic energy and contributes to the reduction of the velocity differences between the MC and the FP. The large scale vortices that are generated in the shear layer are anisotropic, provoking the formation of secondary flow cells that influence the primary velocity distribution. These threedimensional turbulent structures can be reasonable well reproduced by a simple anisotropic model (Algebraic Stress Model). The isotropic models are capable of simulating the boundary layer, especially the model base in k-ω equations, but cannot simulate the shear layer that develops at the interface

TiO2-Photocatalyzed degradation of phenol in saline media in an annular reactor: hydrodynamics, lumped kinetics, intermediates, and acute toxicity

The photocatalytic degradation of phenol in aqueous suspensions of TiO2 under different salt concentrations in an annular reactor has been investigated. In all cases, complete removal of phenol and mineralization degrees above 90% were achieved. The reactor operational parameters were optimized and its hydrodynamics characterized in order to couple mass balance equations with kinetic ones. The photodegradation of the organics followed a Langmuir-Hinshelwood-Hougen-Watson lumped kinetics. From GC/MS analyses, several intermediates formed during oxidation have been identified. The main ones were catechol, hydroquinone, and 3-phenyl-2-propenal, in this order. The formation of negligible concentrations of 4-chlorophenol was observed only in high salinity medium. Acute toxicity was determined by using Artemia sp. as the test organism, which indicated that intermediate products were all less toxic than phenol and a significant abatement of the overall toxicity was accomplished, regardless of the salt concentration.(FAPERJ) Fundacao de Amparo a Pesquisa do Estado do Rio de JaneiroFUJBCNPqPADC

A dynamic method for charging-up calculations: the case of GEM

The simulation of Micro Pattern Gaseous Detectors (MPGDs) signal response is an important and powerful tool for the design and optimization of such detectors. However, several attempts to simulate exactly the effective charge gain have not been completely successful. Namely, the gain stability over time has not been fully understood. Charging-up of the insulator surfaces have been pointed as one of the responsible for the difference between experimental and Monte Carlo results. This work describes two iterative methods to simulate the charging-up in one MPGD device, the Gas Electron Multiplier (GEM). The first method uses a constant step for avalanches time evolution, very detailed, but slower to compute. The second method uses a dynamic step that improves the computing time. Good agreement between both methods was reached. Despite of comparison with experimental results shows that charging-up plays an important role in detectors operation, should not be the only responsible for the difference between simulated and measured effective gain, but explains the time evolution in the effective gain.Comment: Minor changes in grammatical statements and inclusion of some important information about experimental setup at section "Comparison with experimental results

Contribuição de espécies florestais para fins energéticos sobre algumas características químicas de um podzólico amarelo impactado por usos anteriores no município de Iranduba-AM.

O objetivo desse trabalho e selecionar especies nativas e/ou exoticas com potencial para produzir lenha e derivados, e estudar tecnicas de manejo adequadas a implantacao de producao de lenha em plantios ordenados.bitstream/CPAA-2009-09/6300/1/IT_11_2000.pd