614 research outputs found
Proof of a conjecture by Gazeau et al. using the Gould Hopper polynomials
We prove the "strong conjecture" expressed by Gazeau et al. in
arXiv:1203.3936v1 [math-ph] about the coefficients of the Taylor expansion of
the exponential of a polynomial. This implies the "weak conjecture" as a
special case. The proof relies mainly about properties of the Gould-Hopper
polynomials
Spectral imbalance and the normalized dissipation rate of turbulence
The normalized turbulent dissipation rate is studied in decaying
and forced turbulence by direct numerical simulations, large-eddy simulations,
and closure calculations. A large difference in the values of is
observed for the two types of turbulence. This difference is found at moderate
Reynolds number, and it is shown that it persists at high Reynolds number,
where the value of becomes independent of the Reynolds number, but
is still not unique. This difference can be explained by the influence of the
nonlinear cascade time that introduces a spectral disequilibrium for
statistically nonstationary turbulence. Phenomenological analysis yields simple
analytical models that satisfactorily reproduce the numerical results. These
simple spectral models also reproduce and explain the increase of
at low Reynolds number that is observed in the simulations
Detection of the tagged or untagged photons in acousto-optic imaging of thick highly scattering media by photorefractive adaptive holography
We propose an original adaptive wavefront holographic setup based on the
photorefractive effect (PR), to make real-time measurements of acousto-optic
signals in thick scattering media, with a high flux collection at high rates
for breast tumor detection. We describe here our present state of art and
understanding on the problem of breast imaging with PR detection of the
acousto-optic signal
Numerical studies towards practical large-eddy simulation
Large-eddy simulation developments and validations are presented for an
improved simulation of turbulent internal flows. Numerical methods are proposed
according to two competing criteria: numerical qualities (precision and
spectral characteristics), and adaptability to complex configurations. First,
methods are tested on academic test-cases, in order to abridge with fundamental
studies. Consistent results are obtained using adaptable finite volume method,
with higher order advection fluxes, implicit grid filtering and "low-cost"
shear-improved Smagorinsky model. This analysis particularly focuses on mean
flow, fluctuations, two-point correlations and spectra. Moreover, it is shown
that exponential averaging is a promising tool for LES implementation in
complex geometry with deterministic unsteadiness. Finally, adaptability of the
method is demonstrated by application to a configuration representative of
blade-tip clearance flow in a turbomachine
Dix ans de surveillance de la faune aquatique des rivières d'Afrique de l'Ouest traitées contre les simulies (Diptera : Simuliidae), agents vecteurs de l'onchocercose humaine
Phthalocyanine-based dumbbell-shaped molecule: synthesis, structure and charge transport studies
International audienceWe describe the synthesis of a fully conjugated donor-acceptor-donor triad (ZnPc-BTD-ZnPc) made of zinc phthalocyanine donor fragments (ZnPc) at both ends of a benzothiadiazole-based central dye (BTD). The molecule exhibits a broad absorption in the whole visible range. The introduction of sterically demanding alkoxy chains to the ZnPc fragments is found to limit the molecular organization to a short-range columnar order and the charge-carrier mobility to moderate values, but provides outstanding solubilities in organic solvents
Le défigement linguistique comme recours stylistique, et les écueils traductologiques induits de l’espagnol vers le français
The man\u27s gaze transcends reality to so often cosmetic purposes. Referring to literature, here we will only tackle the part of the narrative creation which are the metaphorical interpretation and its derivatives to linger over this other type of diversion realized by the language de-fossilization in its phraseology and lexical applications, leading to many puns.
The translator must accommodate to this sign of discursive freedom of authors, establishing semantic and semiotic relations of collusion between the source language and the target language. This is what we will develop on the basis of about ten illustrations from Hispanic literature. For each case, we will emphasize the intuitive logic of the original find, to propose its transfer in French, pointing that through a translatological "intuitivo-cognitive" posture, the translator can develop his very own creativity, a true wager of literary faithfulness
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
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