199 research outputs found
A Lean Methane Prelixed Laminar Flame Doped witg Components of Diesel Fuel. Part I: n)Butylbenzene
To better understand the chemistry involved during the combustion of
components of diesel fuel, the structure of a laminar lean premixed methane
flame doped with n-butylbenzene has been investigated. The inlet gases
contained 7.1% (molar) of methane, 36.8% of oxygen and 0.96% of n-butylbenzene
corresponding to an equivalence ratio of 0.74 and a ratio C10H14 / CH4 of
13.5%. The flame has been stabilized on a burner at a pressure of 6.7 kPa using
argon as diluent, with a gas velocity at the burner of 49.2 cm/s at 333 K.
Quantified species included the usual methane C0-C2 combustion products, but
also 16 C3-C5 hydrocarbons, 7 C1-C3 oxygenated compounds, as well as 20
aromatic products, namely benzene, toluene, phenylacetylene, styrene,
ethylbenzene, xylenes, allylbenzene, propylbenzene, cumene, methylstyrenes,
butenylbenzenes, indene, indane, naphthalene, phenol, benzaldehyde, anisole,
benzylalcohol, benzofuran, and isomers of C10H10 (1-methylindene,
dihydronaphtalene, butadienylbenzene). A new mechanism for the oxidation of
n-butylbenzene is proposed whose predictions are in satisfactory agreement with
measured species profiles in flames and flow reactor experiments. The main
reaction pathways of consumption of n butylbenzene have been derived from flow
rate analyses
WEIRD: Wide-orbit Exoplanet search with InfraRed Direct imaging
We report results from the Wide-orbit Exoplanet search with InfraRed Direct
imaging (WEIRD), a survey designed to search for Jupiter-like companions on
very wide orbits (1000 to 5000 AU) around young stars (120 Myr) that are
known members of moving groups in the solar neighborhood (70 pc). Sharing
the same age, distance, and metallicity as their host while being on large
enough orbits to be studied as "isolated" objects make such companions prime
targets for spectroscopic observations and valuable benchmark objects for
exoplanet atmosphere models. The search strategy is based on deep imaging in
multiple bands across the near-infrared domain. For all 177 objects of our
sample, , , [3.6] and [4.5] images were obtained with
CFHT/MegaCam, GEMINI/GMOS, CFHT/WIRCam, GEMINI/Flamingos-2, and /IRAC.
Using this set of 4 images per target, we searched for sources with red
and colors, typically reaching good completeness
down to 2Mjup companions, while going down to 1Mjup for some targets, at
separations of AU. The search yielded 4 candidate companions with
the expected colors, but they were all rejected through follow-up proper motion
observations. Our results constrain the occurrence of 1-13 Mjup planetary-mass
companions on orbits with a semi-major axis between 1000 and 5000 AU at less
than 0.03, with a 95\% confidence level.Comment: 55 pages, 16 figures, accepted to A
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