71,208 research outputs found
Statistical Mesoscopic Hydro-Thermodynamics: The Description of Kinetics and Hydrodynamics of Nonequilibrium Processes in Single Liquids
Hydrodynamics, a term apparently introduced by Daniel Bernoulli (1700-1783)
to comprise hydrostatic and hydraulics, has a long history with several
theoretical approaches. Here, after a descriptive introduction, we present
so-called mesoscopic hydro-thermodynamics, which is also referred to as
higher-order generalized hydrodynamics, built within the framework of a
mechanical-statistical formalism. It consists of a description of the material
and heat motion of fluids in terms of the corresponding densities and their
associated fluxes of all orders. In this way, movements are characterized in
terms of intermediate to short wavelengths and intermediate to high
frequencies. The fluxes have associated Maxwell-like times, which play an
important role in determining the appropriate contraction of the description
(of the enormous set of fluxes of all orders) necessary to address the
characterization of the motion in each experimental setup. This study is an
extension of a preliminary article: Physical Review E \textbf{91}, 063011
(2015)
Application of the method of multiple scales to unravel energy exchange in nonlinear locally resonant metamaterials
In this paper, the effect of weak nonlinearities in 1D locally resonant
metamaterials is investigated via the method of multiple scales. Commonly
employed to the investigate the effect of weakly nonlinear interactions on the
free wave propagation through a phononic structure or on the dynamic response
of a Duffing oscillator, the method of multiple scales is here used to
investigate the forced wave propagation through locally resonant metamaterials.
The perturbation approach reveals that energy exchange may occur between
propagative and evanescent waves induced by quadratic nonlinear local
interaction
Cosmology with intensity mapping techniques using atomic and molecular lines
We present a systematic study of the intensity mapping technique using
updated models for the different emission lines from galaxies and identify
which ones are more promising for cosmological studies of the post reionization
epoch. We consider the emission of , , H,
optical and infrared oxygen lines, nitrogen lines, CII and the CO rotational
lines. We then identify that , , OII, CII and
the lowest rotational CO lines are the best candidates to be used as IM probes.
These lines form a complementary set of probes of the galaxies emission
spectra. We then use reasonable experimental setups from current, planned or
proposed experiments to access the detectability of the power spectrum of each
emission line. Intensity mapping of emission from to 3
will be possible in the near future with HETDEX, while far-infrared lines
require new dedicated experiments. We also show that the proposed SPHEREx
satellite can use OII and IM to study the large-scale
distribution of matter in intermediate redshifts of 1 to 4. We found that
submilimeter experiments with bolometers can have similar performances at
intermediate redshifts using CII and CO(3-2).Comment: 18 pages, 21 figures, 5 tables, published in MNRAS, typos correcte
Quantitative chemical tagging, stellar ages and the chemo-dynamical evolution of the Galactic disc
The early science results from the new generation of high-resolution stellar
spectroscopic surveys, such as GALAH and the Gaia-ESO survey, will represent
major milestones in the quest to chemically tag the Galaxy. Yet this technique
to reconstruct dispersed coeval stellar groups has remained largely untested
until recently. We build on previous work that developed an empirical chemical
tagging probability function, which describes the likelihood that two field
stars are conatal, that is, they were formed in the same cluster environment.
In this work we perform the first ever blind chemical tagging experiment, i.e.,
tagging stars with no known or otherwise discernable associations, on a sample
of 714 disc field stars with a number of high quality high resolution
homogeneous metal abundance measurements. We present evidence that chemical
tagging of field stars does identify coeval groups of stars, yet these groups
may not represent distinct formation sites, e.g. as in dissolved open clusters,
as previously thought. Our results point to several important conclusions,
among them that group finding will be limited strictly to chemical abundance
space, e.g. stellar ages, kinematics, colors, temperature and surface gravity
do not enhance the detectability of groups. We also demonstrate that in
addition to its role in probing the chemical enrichment and kinematic history
of the Galactic disc, chemical tagging represents a powerful new stellar age
determination technique.Comment: 12 pages, 9 figures, accepted for publication in Monthly Notices of
the Royal Astronomical Society (MNRAS
Spin dependent transport in organic light-emitting diodes
Electrically Detected Magnetic Resonance (EDMR) was used to study a series of
multilayer organic devices based on aluminum (III) 8-hydroxyquinoline. These
devices were designed to identify the micoscopic origin of different spin
dependent process, i.e. hopping and exciton formation. EDMR is demonstrated to
probe molecular orbitals of charge, and thus indirectly explore interfaces,
exciton formation, charge accumalation and electric fields in operating organic
based devices
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