85 research outputs found
Determination of the Properties of Composite Materials Thanks to Digital Image Correlation Measurements
AbstractDesigning composite structures for civil aircrafts necessitates a better understanding of the damage and failure mechanisms occurring in these components through experimental test campaigns and associated numerical simulations. These experimental tests have been performed at Onera using different classical measurement techniques (LVDT sensor, strain gauges…) and digital image correlation (DIC). The additional information provided by DIC allows (i) to validate the boundary conditions of the tests, (ii) to cross-check the measurements with other techniques, (iii) to improve the understanding of the physical mechanisms and (iv) to validate the predictions of the finite element simulations
Metabolomics Study of Urine in Autism Spectrum Disorders Using a Multiplatform Analytical Methodology
Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder with no clinical
biomarker. Aims of this study were to characterize a metabolic signature of ASD, and to
evaluate multi-platform analytical methodologies in order to develop predictive tools for
diagnosis and disease follow up.
Urines were analyzed using: 1H- and 1
H-13C-NMR-based approaches and LC-HRMS-based
approaches (ESI+ and ESI- on a HILIC and C18 chromatography column). Data tables
obtained from the six analytical modalities on a training set of 46 urines (22 autistic children
and 24 controls) were processed by multivariate analysis (OPLS-DA). Prediction of each of
these OPLS-DA models were then evaluated using a prediction set of 16 samples (8 autistic
children and 8 controls) and ROC curves. Thereafter, a data fusion block-scaling OPLS-DA
model was generated from the 6 best models obtained for each modality. This fused OPLSDA
model showed an enhanced performance (R
2Y(cum)=0.88, Q
2
(cum)=0.75) compared to
each analytical modality model, as well as a better predictive capacity (AUC=0.91, p-value
0.006). Metabolites that are most significantly different between autistic and control children
(p<0.05) are indoxyl sulfate, N-\u2329-Acetyl-L-arginine, methyl guanidine and
phenylacetylglutamine. This multi-modality approach has the potential to contribute to find
robust biomarkers and characterize a metabolic phenotype of the ASD population
X-ray Photoemission Study of MgB2
A c-axis oriented thin film and a high density sintered pellet of MgB2 have
been studied by x-ray photoemission spectroscopy, and compared to measurements
from MgO and MgF2 single crystals. The as-grown surface has a layer which is
Mg-rich and oxidized, which is effectively removed by a nonaqueous etchant. The
subsurface region of the pellet is Mg-deficient. This nonideal near-surface
region may explain varied scanning tunneling spectroscopy results. The MgB2
core level and Auger signals are similar to measurements from metallic Mg and
transition metal diborides, and the measured valence band is consistent with
the calculated density of states.Comment: 19 pages, 6 figures; Submitted to Phys. Rev. B; added references and
new data on film
Analysis of delamination onset and growth induced by laser decomposition within carbon/epoxy composite laminates
International audienceFire-induced decomposition of composite materials involves complex and coupled multi-physics phenomena the understanding of which is limited when performing standard tests such cone calorimeter, FAR25.856(b):2003 or ISO2685:1998(e). It is proposed to address this issue under controlled environment surrounding the material using the BLADE facility developed at ONERA. Decomposition and damage are analysed experimentally to investigate the anisotropic and heterogeneous thermo-chemical behaviour of decomposing composite laminates submitted to a laser heating within an enclosure. Accurate heat transfer measurements are correlated with micrographic analysis to identify the delamination onset and growth induced by the laser decomposition
Estimate of average production costs for three dairies of Maule Region, Chile: a case study
Se estimaron costos medios mensuales para el año 1998 de la
producción de leche en tres lecherÃas ubicadas en la
provincia de Linares (35º51' lat. S. y 71º35' long. O.),
Región del Maule, Chile. Las explotaciones lecheras están
asociadas a la empresa PROLECHE S.A., formada con apoyo financiero de
la Corporación de Fomento de la Producción (CORFO) para la
gestión asociativa. La tasa de descuento relevante fue estimada
utilizando el Modelo de Valorización de Activos de Capital (CAPM)
y el Costo Promedio Ponderado del Capital (WACC). El costo medio total
por litro de leche fue calculado sumando el costo medio del capital y
el costo medio de la operación. Los principales resultados indican
que el costo medio total fluctúa entre 0,276 y 0,619 para el
predio 1, entre 0,171 y 0,282 para el predio 2, y entre 0,160 y 0,316
para el predio 3. Los menores costos medios totales se presentaron en
los meses de primavera y verano debido a la mayor producción de
leche y disponibilidad de forraje de menor costo. Los predios 2 y 3 se
ubican en un rango de costos medios totales anuales intermedios,
mientras que el valor para el predio 1 es muy superior en relación
a los valores reportados por la literatura
Experimental characterization and numerical modeling of damage at the mesoscopic scale of woven polymer matrix composites under quasi-static tensile loading
International audienc
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