4,159 research outputs found
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
Root traits analysis of recombinant inbred lines underlying phosphorus acquisition efficiency in maize.
Severe hyperchloremic metabolic acidosis with SGLT2 inhibitors in patients with urinary diversion
info:eu-repo/semantics/publishedVersio
Conditional stability of unstable viscous shock waves in compressible gas dynamics and MHD
Extending our previous work in the strictly parabolic case, we show that a
linearly unstable Lax-type viscous shock solution of a general quasilinear
hyperbolic--parabolic system of conservation laws possesses a
translation-invariant center stable manifold within which it is nonlinearly
orbitally stable with respect to small perturbations, converging
time-asymptotically to a translate of the unperturbed wave. That is, for a
shock with unstable eigenvalues, we establish conditional stability on a
codimension- manifold of initial data, with sharp rates of decay in all
. For , we recover the result of unconditional stability obtained by
Mascia and Zumbrun. The main new difficulty in the hyperbolic--parabolic case
is to construct an invariant manifold in the absence of parabolic smoothing.Comment: 32p
Metodologia de extração de proteínas em torta de mamona e pinhão manso para análise por eletroforese (SDS-PAGE).
bitstream/item/74838/1/pub-151.pd
Avaliação de espécies florestais e pastagens em sistemas silvipastoris em Paragominas, Pará, Brasil.
Propor modelos alternativos de uso-da-terra, econômicos e ecologicamente sustentáveis, tem sido um grande desafio da pesquisa agrícola na Amazônia. Os sistemas silvipastoris têm sido considerados promissores para integrar o cultivo arbóreo na pecuária e recuperar extensas áreas de pastagens degradadas da Amazônia. Entretanto, ainda carecem de uma base científica que suporte sua recomendação mais ampla. Em Paragominas-PA, foram estudados nove sistemas silvipastoris, de um hectare cada, constituídos da combinação binária de três espécies florestais (Schizolobium amazonicum, Bagassa guianensis e Eucalyptus terenticornis), plantadas em faixas de 6 m e afastadas de 12 m, com três pastagens (Brachiaria brizantha cv. Marandu, Brachiaria humidicola e Panicum maximum cv. Colonião/Brachiaria dictyoneura). Novilhos pastaram as parcelas experimentais simulando um sistema rotativo, com 14 dias de permanência e 42 dias de descanso. Foram medidos a altura e o diâmetro à altura do peito das espécies florestais, a massa de forragem e a proteína bruta das pastagens. Os componentes silvipastoris de melhor desempenho foram o Schizolobium amazonicum e Brachiaria brizantha cv Marandu. Dos pontos de vista florestal e pastoril, a combinação silvipastoril mais promissora foi Schizolobium amazonicum - Brachiaria brizantha cv Marandu
Petrographical and geochemical signatures of the Granja paragneisses (NW Ceará, Brasil)
The Granja Granulitic Complex
(GCC) constitutes a NE–SW
trending high-grade
metamorphic belt occupying the
western sector of the Médio
Coreaú Domain (NW Ceará,
Brasil) (Figs. 1 and 2).
According to the published data,
the GCC represents a segment
of the Paleoproterozoic
basement intensely reworked
during the Brasiliano Orogeny.
Lithologically, the GCC is mainly
composed of garnet-sillimanite
migmatitic paragneisses,
enclosing discontinuous lenses
of mafic granulites and
enderbites.
At outcrop scale, the GCC
gneisses are well-foliated fineto
medium-grained grey rocks
showing a stromatic layering
parallel to the main regional
fabric (Fig. 3). The occurrence of
lenses of leucocratic quartzfeldspathic
material interlayered
with the host paragneisses
indicates that these rocks
reached partial melting
conditions during the Brasiliano
orogenic event (≈ 600 Ma).
Petrographically, the gneisses
are characterized by the
presence of mineral
assemblages dominated by
garnet, sillimanite and biotite
with moderate amounts of
quartz, plagioclase, cordierite
and K-feldspar (Figs. 4a-b).
Twelve whole-rock samples
were analyzed for major and
trace elements. As shown in
Graph 1, all the analyzed
samples plot in the sedimentary
field. Their REE patterns closely
resemble those of PAAS (PostArchean
average Australian
Shale) confirming the
sedimentary origin of the
paragneiss protoliths (Graph 2).
Geochemical data also suggest
that these sediments derived
from source areas of felsic to
intermediate composition and
were deposited in a tectonically
active continental margin
(Graphs 3 and 4)
Determinação da ET de referência pela razão de Bowen com psicrômetros instalados a diferentes alturas.
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