20,360 research outputs found
Inspection and diagnosis tests for structural safety evaluation: A case study
Diagnosis and assessment of existing structures is a developing area due to the appearance of a high number of building defects, structural and non-structural deterioration and precocious loss of quality, and, consequently, lower expected durability. With the aim of verifying the viability of rehabilitation or the need to demolish an existing fifteen year old parking building, several inspections and diagnostic non-destructive and destructive testing, visual inspection, were carried out to evaluate the structural safety conditions
A Direct Multigrid Poisson Solver for Oct-Tree Adaptive Meshes
We describe a finite-volume method for solving the Poisson equation on
oct-tree adaptive meshes using direct solvers for individual mesh blocks. The
method is a modified version of the method presented by Huang and Greengard
(2000), which works with finite-difference meshes and does not allow for shared
boundaries between refined patches. Our algorithm is implemented within the
FLASH code framework and makes use of the PARAMESH library, permitting
efficient use of parallel computers. We describe the algorithm and present test
results that demonstrate its accuracy.Comment: 10 pages, 6 figures, accepted by the Astrophysical Journal; minor
revisions in response to referee's comments; added char
X-ray image separation via coupled dictionary learning
In support of art investigation, we propose a new source sepa- ration method
that unmixes a single X-ray scan acquired from double-sided paintings. Unlike
prior source separation meth- ods, which are based on statistical or structural
incoherence of the sources, we use visual images taken from the front- and
back-side of the panel to drive the separation process. The coupling of the two
imaging modalities is achieved via a new multi-scale dictionary learning
method. Experimental results demonstrate that our method succeeds in the
discrimination of the sources, while state-of-the-art methods fail to do so.Comment: To be presented at the IEEE International Conference on Image
Processing (ICIP), 201
Multi-modal dictionary learning for image separation with application in art investigation
In support of art investigation, we propose a new source separation method
that unmixes a single X-ray scan acquired from double-sided paintings. In this
problem, the X-ray signals to be separated have similar morphological
characteristics, which brings previous source separation methods to their
limits. Our solution is to use photographs taken from the front and back-side
of the panel to drive the separation process. The crux of our approach relies
on the coupling of the two imaging modalities (photographs and X-rays) using a
novel coupled dictionary learning framework able to capture both common and
disparate features across the modalities using parsimonious representations;
the common component models features shared by the multi-modal images, whereas
the innovation component captures modality-specific information. As such, our
model enables the formulation of appropriately regularized convex optimization
procedures that lead to the accurate separation of the X-rays. Our dictionary
learning framework can be tailored both to a single- and a multi-scale
framework, with the latter leading to a significant performance improvement.
Moreover, to improve further on the visual quality of the separated images, we
propose to train coupled dictionaries that ignore certain parts of the painting
corresponding to craquelure. Experimentation on synthetic and real data - taken
from digital acquisition of the Ghent Altarpiece (1432) - confirms the
superiority of our method against the state-of-the-art morphological component
analysis technique that uses either fixed or trained dictionaries to perform
image separation.Comment: submitted to IEEE Transactions on Images Processin
REDUCED-SCALE STUDY OF LIQUID FUEL STORAGE TANK FIRE USING FIRE DYNAMICS SIMULATOR
Most of the accidents that occur in liquid fuel storage tank parks are caused by fire. This paper presents a numerical study using Large Eddy Simulation through Fire Dynamics Simulator (FDS) for the simulation of liquid fuel (ethanol) storage tanks at different scales (real-scale 1:1, and reduced- scales, 1:2, 1:4, 1:8). This paper proposes correlations for flame height, and temperature profile and radiative heat flux profile in the region adjacent to the tanks. Correlations have as inputs the diameters of the tanks in real- and reduced-scale, temperature profiles and radiative heat flux profiles for a reduced-scale tank simulation, and then provide as outputs flame height and temperature profiles and radiative heat flux profiles for the tank in real- scale. Percentage errors of the correlations found in this study are lower than 2.0% and 0.6% for the maximum radiative heat flux and maximum temperature, respectively
Chemosymbiotic species from the Gulf of Cadiz
Previous work in the mud volcanoes from the Gulf
of Cadiz (South Iberian Margin) revealed a high number
of chemosymbiotic species, namely bivalves and siboglinid
polychaetes. In this study we give an overview of the distribution
and life styles of these species in the Gulf of Cadiz,
determine the role of autotrophic symbionts in the nutrition
of selected species using stable isotope analyses ( 13C, 15N
and 34S) and investigate the intra-specific variation of isotope
signatures within and between study sites. During our
studies, we identified twenty siboglinidae and nine bivalve
chemosymbiotic species living in fifteen mud volcanoes.
Solemyid bivalves and tubeworms of the genus Siboglinum
are widespread in the study area, whereas other species
were found in a single mud volcano (e.g. “Bathymodiolus”
mauritanicus) or restricted to deeper mud volcanoes (e.g.
Polybrachia sp., Lamelisabella denticulata). Species distribution
suggests that different species may adjust their position
within the sediment according to their particular needs,
and to the intensity and variability of the chemical substrata
supply. Tissue stable isotope signatures for selected
species are in accordance with values found in other studies,
with thiotrophy as the dominant nutritional pathway, and
with methanotrophy and mixotrophy emerging as secondary
strategies. The heterogeneity in terms of nutrient sources (expressed
in the high variance of nitrogen and sulphur values)
and the ability to exploit different resources by the different
species may explain the high diversity of chemosymbiotic
species found in the Gulf of Cadiz. This study increases the
knowledge on distributional patterns and resource partitioning
of chemosymbiotic species and highlights how trophic
fuelling varies on spatial scales with direct implications to
seep assemblages and potentially to the biodiversity of continental
margin
Produção de pólen por abelhas melíferas (Apis mellifera) em área de cultivo de manga (Mangifera indica L.) no projeto irrigado de Maniçoba, Juazeiro-BA.
Para incrementar a produção da manga em áreas irrigadas no Vale do Submédio São Francisco, os produtores utilizam colmeias de abelhas Apis mellifera, que realizam sua polinização. Entretanto, não se sabe se paralelamente os apicultores poderiam aproveitar as abelhas nas áreas de cultivo também para a produção de pólen apícola. Desta forma, este trabalho foi realizado com o objetivo de avaliar a produção de pólen por colmeias de A. mellifera em área de cultivo de manga no projeto irrigado de Maniçoba, Juazeiro-BA. O pólen foi coletado por meio de coletor de pólen frontal em duas colmeias previamente padronizadas quanto à quantidade de áreas de cria e alimento estocado. As coletas foram realizadas a cada 24 horas, por cinco dias consecutivos, em outubro de 2011. Os grãos de pólen retirados dos coletores foram armazenados em embalagens plásticas individuais, secados em estufa a 40-50ºC, durante 24 horas e, em seguida, pesados em balança de precisão. A coleta de pólen foi baixa em ambas as colônias durante todo o período experimental. No entanto, em cada dia, a colônia 1 coletou relativamente mais pólen que a colônia 2, embora estas diferenças não foram significativas. Seria necessário repetir o experimento em maior número de áreas de cultivo para confirmar que a produção é realmente muito baixa, e assim, não indicar esta atividade como alternativa para os apicultores da região
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