601 research outputs found
Calculation of the separation streamlines of barchans and transverse dunes
We use FLUENT to calculate the wind profile over barchans and transverse
dunes. The form of the streamlines of flow separation at the lee side of the
dunes is determined for a symmetric barchan dune in three dimensions, and for
the height profile of a measured transverse dune field in the Len\c{c}\'ois
Maranhenses.Comment: 6 pages including 5 figures. Proceedings of PSIS 200
Traveling length and minimal traveling time for flow through percolation networks with long-range spatial correlations
We study the distributions of traveling length l and minimal traveling time t
through two-dimensional percolation porous media characterized by long-range
spatial correlations. We model the dynamics of fluid displacement by the
convective movement of tracer particles driven by a pressure difference between
two fixed sites (''wells'') separated by Euclidean distance r. For strongly
correlated pore networks at criticality, we find that the probability
distribution functions P(l) and P(t) follow the same scaling Ansatz originally
proposed for the uncorrelated case, but with quite different scaling exponents.
We relate these changes in dynamical behavior to the main morphological
difference between correlated and uncorrelated clusters, namely, the
compactness of their backbones. Our simulations reveal that the dynamical
scaling exponents for correlated geometries take values intermediate between
the uncorrelated and homogeneous limiting cases
Brazilian elections: voting for a scaling democracy
The proportional elections held in Brazil in 1998 and 2002 display identical
statistical signatures. In particular, the distribution of votes among
candidates includes a power-law regimen. We suggest that the rationale behind
this robust scaling invariance is a multiplicative process in which the voter's
choice for a candidate is governed by a product of probabilities.Comment: 4 pages, 2 figure
Heat Transport through Rough Channels
We investigate the two-dimensional transport of heat through viscous flow
between two parallel rough interfaces with a given fractal geometry. The flow
and heat transport equations are solved through direct numerical simulations,
and for different conduction-convection conditions. Compared with the behavior
of a channel with smooth interfaces, the results for the rough channel at low
and moderate values of the Peclet number indicate that the effect of roughness
is almost negligible on the efficiency of the heat transport system. This is
explained here in terms of the Makarov's theorem, using the notion of active
zone in Laplacian transport. At sufficiently high Peclet numbers, where
convection becomes the dominant mechanism of heat transport, the role of the
interface roughness is to generally increase both the heat flux across the wall
as well as the active length of heat exchange, when compared with the smooth
channel. Finally, we show that this last behavior is closely related with the
presence of recirculation zones in the reentrant regions of the fractal
geometry.Comment: 12 pages, 8 figure
Selection of strawberry cultivars with tolerance to Tetranychus urticae (Acari: Tetranychidae) and high yield under different managements.
Tetranychus urticae Koch (Acari: Tetranychidae) is considered the main pest of strawberry. Several factors can favor its development, among them the genotype susceptibility and cropping system. The aims of this study were to evaluate the agronomic performance of strawberry cultivars under different managements and to identify strawberry cultivars that meet tolerance to T. urticae and high fruit yield. Thirteen cultivars of strawberry ('Albion', 'Aleluia', 'Aromas', 'Camarosa', 'Camino Real', 'Campinas', 'Diamante', 'Dover', 'Festival', 'Seascape', 'Toyonoka', 'Tudla', and 'Ventana') under three managements (open field, low tunnel, and high tunnel) were evaluated. The T. urticae attack to different cultivars was influenced by managements, being low tunnel the one that provided higher infestations in the most evaluated cultivars. 'Camarosa' was the cultivar with the lower incidence of pest and 'Dover' had the higher infestation. The genotype most suitable for growing under different managements is the 'Festival' genotype, since it meets tolerance to T. urticae, high fruit yield, and phenotypic stability
The Complex Topology of Chemical Plants
We show that flowsheets of oil refineries can be associated to complex
network topologies that are scale-free, display small-world effect and possess
hierarchical organization. The emergence of these properties from such man-made
networks is explained as a consequence of the currently used principles for
process design, which include heuristics as well as algorithmic techniques. We
expect these results to be valid for chemical plants of different types and
capacities.Comment: 7 pages, 5 figures and 1 tabl
Black hole thermodynamical entropy
As early as 1902, Gibbs pointed out that systems whose partition function
diverges, e.g. gravitation, lie outside the validity of the Boltzmann-Gibbs
(BG) theory. Consistently, since the pioneering Bekenstein-Hawking results,
physically meaningful evidence (e.g., the holographic principle) has
accumulated that the BG entropy of a black hole is
proportional to its area ( being a characteristic linear length), and
not to its volume . Similarly it exists the \emph{area law}, so named
because, for a wide class of strongly quantum-entangled -dimensional
systems, is proportional to if , and to if
, instead of being proportional to (). These results
violate the extensivity of the thermodynamical entropy of a -dimensional
system. This thermodynamical inconsistency disappears if we realize that the
thermodynamical entropy of such nonstandard systems is \emph{not} to be
identified with the BG {\it additive} entropy but with appropriately
generalized {\it nonadditive} entropies. Indeed, the celebrated usefulness of
the BG entropy is founded on hypothesis such as relatively weak probabilistic
correlations (and their connections to ergodicity, which by no means can be
assumed as a general rule of nature). Here we introduce a generalized entropy
which, for the Schwarzschild black hole and the area law, can solve the
thermodynamic puzzle.Comment: 7 pages, 2 figures. Accepted for publication in EPJ
The use of camu-camu (Myrciaria dubia) for the production of a fermented alcoholic beverage
The high levels of ascorbic acid in camu-camu (Myrciaria dubia McVaugh, Myrtaceae) have stimulated interest of extractivists, farmers and consumers. This has led to a need to develop adequate technology for it's production on non-flooded land and the industrial use of this fruit. This study had as its main objective to verify if camu-camu is adequate for the production of fermented alcoholic beverages, measuring the effect of blanching the fruit and the incorporation of the fruit peel with the fruit pulp on the nutritional and sensory characteristics of the drink. The fruits were separated into 4 groups, two being blanched (90 ºC for 7 minutes). After the pulp was removed, the peels of one group from each blanching treatment were incorporated into the respective pulps and their chemical composition evaluated. After sugar correction of the must, pasteurisation, fermentation (25 days), decanting, pasteurisation (70 ºC for 15 minutes), filtering and clarification, the beverages were evaluated as to their chemical composition, sweetened and submitted to sensory analysis. Blanching reduced the concentration of ascorbic acid in the pulps (33 %) and the addition of the peel increased the amount of dry matter (39 % in pulp), ascorbic acid (33 % in pulp, 23 % in must and 50 % in drink) and phenolic compounds (50 % in drink). The sensory profile and acceptability suggest that camu-camu is adequate for the production of fermented alcoholic beverages and that the addition of the peel to the pulp contributes positively to it's acceptability (6.7 with versus 6.2 without, of 9 points possible). The beverage had flavour characteristic of the fruit, a orangish-red color and agreeable taste.", 'enO elevado teor de ácido ascórbico no camu-camu (Myrciaria dubia McVaugh, Myrtaceae) desperta o interesse de extrativistas, agricultores e consumidores, e leva à necessidade de desenvolvimento de tecnologias adequadas para produção em terra firme e aproveitamento industrial do fruto. Este trabalho teve por objetivo verificar a adequação do camu-camu para a produção de bebida alcoólica fermentada, assim como o efeito do branqueamento do fruto e da incorporação da casca à polpa nas características nutricionais e sensoriais da bebida. Os frutos foram separados em quatro lotes, sendo dois branqueados (90 ºC por 7 min). Após a despolpa, as cascas de um lote de cada tratamento (com e sem branqueamento) foram incorporadas às respectivas polpas e avaliadas quanto à composição química (umidade, pH, acidez, sólidos solúveis, açúcares, ácido ascórbico, compostos fenólicos, antocianinas e flavonóides). Após a correção do mosto com açúcar, pasteurização, fermentação (25 dias), trasfega, pasteurização (70 ºC por 15 min), filtragem e clarificação, as bebidas foram avaliadas quanto a composição química, edulcoradas e submetidas à análise sensorial. O branqueamento reduziu a concentração de ácido ascórbico das polpas (33 %) e a agregação da casca aumentou os teores de matéria seca (39 % polpa), ácido ascórbico (33 % na polpa, 23 % no mosto e 50 % na bebida) e fenólicos (50 % bebida). O perfil sensorial e a aceitabilidade sugerem que o camu-camu é adequado para a produção de bebida alcoólica fermentada e que a agregação da casca à polpa contribuiu positivamente para a aceitabilidade (6,7 com casca e 6,2 sem casca, na escala de 9 pontos). As bebidas apresentaram flavor característico do fruto, limpidez, coloração vermelho-laranjada e sabor agradável
Planar and Poly-Arc Lombardi Drawings
In Lombardi drawings of graphs, edges are represented as circular arcs, and
the edges incident on vertices have perfect angular resolution. However, not
every graph has a Lombardi drawing, and not every planar graph has a planar
Lombardi drawing. We introduce k-Lombardi drawings, in which each edge may be
drawn with k circular arcs, noting that every graph has a smooth 2-Lombardi
drawing. We show that every planar graph has a smooth planar 3-Lombardi drawing
and further investigate topics connecting planarity and Lombardi drawings.Comment: Expanded version of paper appearing in the 19th International
Symposium on Graph Drawing (GD 2011). 16 pages, 8 figure
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