577 research outputs found
Comedia nueva intitulada Mal genio y buen corazon, en tres actos
Carlos Gibert y Tutó imprime en Barcelona entre 1775 y 179
Atilio Regulo
Pie de imp. consta en colofón[entre 1775 y 1796]Gibert y Tutó imprimió entre 1775 y 1796
Lagrangian temperature, velocity and local heat flux measurement in Rayleigh-Benard convection
We have developed a small, neutrally buoyant, wireless temperature sensor.
Using a camera for optical tracking, we obtain simultaneous measurements of
position and temperature of the sensor as it is carried along by the flow in
Rayleigh-B\'enard convection, at . We report on statistics of
temperature, velocity, and heat transport in turbulent thermal convection. The
motion of the sensor particle exhibits dynamics close to that of Lagrangian
tracers in hydrodynamic turbulence. We also quantify heat transport in plumes,
revealing self-similarity and extreme variations from plume to plume.Comment: 4 page
El conde D. Garci-Sanchez de Castilla : tragedia : en cinco actos
Precede al tit.: "N.99"Copia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 2009-2010Según el "Catálogo de autores teatrales del siglo XVIII" de J. Herrera Navarro, p.481, esta obra es de Lorenzo María de Villarroel y Velazquez y se imprimió por primera vez en 1778Pi de imp. tomado de colofónEl impresor trabajó en Barcelona entre 1775 y 179
Design and operation of a field telescope for cosmic ray geophysical tomography
International audienceThe cosmic ray muon tomography gives an access to the density structure of geological targets. In the present article we describe a muon telescope adapted to harsh environmental conditions. In particular the design optimizes the total weight and power consumption to ease the deployment and increase the autonomy of the detector. The muon telescopes consist of at least two scintillator detection matrices readout by photosensors via optical fibres. Two photosensor options have been studied. The baseline option foresees one multianode photomultiplier (MAPM) per matrix. A second option using one multipixel photon counter (MPPC) per bar is under development. The readout electronics and data acquisition system developed for both options are detailed. We present a first data set acquired in open-sky conditions compared with the muon flux detected across geological objects
A laser-ARPES study of LaNiO3 thin films grown by sputter deposition
Thin films of the correlated transition-metal oxide LaNiO undergo a
metal-insulator transition when their thickness is reduced to a few unit cells.
Here, we use angle-resolved photoemission spectroscopy to study the evolution
of the electronic structure across this transition in a series of epitaxial
LaNiO films of thicknesses ranging from 19 to 2 u.c. grown in situ by RF
magnetron sputtering. Our data show a strong reduction of the electronic mean
free path as the thickness is reduced below 5 u.c. This prevents the system
from becoming electronically two-dimensional, as confirmed by the largely
unchanged Fermi surface seen in our experiments. In the insulating state we
observe a strong suppression of the coherent quasiparticle peak but no clear
gap. These features resemble previous observations of the insulating state of
NdNiO.Comment: Submitted to APL Material
Studies on muon tomography for archaeological internal structures scanning
International audienceMuon tomography is a potential non-invasive technique for internal structure scanning. It has already interesting applications in geophysics and can be used for archaeological purposes. Muon tomography is based on the measurement of the muon flux after crossing the structure studied. Differences on the mean density of these structures imply differences on the detected muon rate for a given direction. Based on this principle, Monte Carlo simulations represent a useful tool to provide a model of the expected muon rate and angular distribution depending on the composition of the studied object, being useful to estimate the expected detected muons and to better understand the experimental results. These simulations are mainly dependent on the geometry and composition of the studied object and on the modelling of the initial muon flux at surface. In this work, the potential of muon tomography in archaeology is presented and evaluated with Monte Carlo simulations by estimating the differences on the muon rate due to the presence of internal structures and its composition. The influence of the chosen muon model at surface in terms of energy and angular distributions in the final result has been also studied. 1. Introduction Among the different applications that muon tomography can have, the scanning of archaeological structures is one of the most innovative one. The principle of the method is straightforward. By detecting the muons that cross the studied object and reconstructing their directions, it is possible to identify the existence of significant differences in the muon rate for a given direction. These differences, consequence of a variation of the mean density of the object traversed by the muons, indicate the possible existence of an internal structure inside the object. The reconstruction of these internal structures by the analysis of the directions of the registered muons is frequently called inverse method. Some features of muon tomography are specially interesting for archaeology. It is a passive method since it is based on the detection of the atmospheric muons, which are naturally produced. Moreover, it is a non-invasive technique since the detector would be placed outside the object to study or, if possible, inside it if internal corridors and halls already exist, as i
Probing quantum and classical turbulence analogy through global bifurcations in a von K\'arm\'an liquid Helium experiment
We report measurements of the dissipation in the Superfluid Helium high
REynold number von Karman flow (SHREK) experiment for different forcing
conditions, through a regime of global hysteretic bifurcation. Our
macroscopical measurements indicate no noticeable difference between the
classical fluid and the superfluid regimes, thereby providing evidence of the
same dissipative anomaly and response to asymmetry in fluid and superfluid
regime. %In the latter case, A detailed study of the variations of the
hysteretic cycle with Reynolds number supports the idea that (i) the stability
of the bifurcated states of classical turbulence in this closed flow is partly
governed by the dissipative scales and (ii) the normal and the superfluid
component at these temperatures (1.6K) are locked down to the dissipative
length scale.Comment: 5 pages, 5 figure
A Preliminary Study of CO2 Flux Measurements by Lidar
A mechanistic understanding of the global carbon cycle requires quantification of terrestrial ecosystem CO2 fluxes at regional scales. In this paper, we analyze the potential of a Doppler DIAL system to make flux measurements of atmospheric CO2 using the eddy-covariance and boundary layer budget methods and present results from a ground based experiment. The goal of this study is to put CO2 flux point measurements in a mesoscale context. In June 2007, a field experiment combining a 2-m Doppler Heterodyne Differential Absorption Lidar (HDIAL) and in-situ sensors of a 447-m tall tower (WLEF) took place in Wisconsin. The HDIAL measures simultaneously: 1) CO2 mixing ratio, 2) atmosphere structure via aerosol backscatter and 3) radial velocity. We demonstrate how to synthesize these data into regional flux estimates. Lidar-inferred fluxes are compared with eddy-covariance fluxes obtained in-situ at 396m AGL from the tower. In cases where the lidar was not yet able to measure the fluxes with acceptable precision, we discuss possible modifications to improve system performance
Averaging bias correction for the future space-borne methane IPDA lidar mission MERLIN
The CNES (French Space
Agency) and DLR (German Space Agency) project MERLIN is a future integrated
path differential absorption (IPDA) lidar satellite mission that aims at
measuring methane dry-air mixing ratio columns (XCH4) in order
to improve surface flux estimates of this key greenhouse gas. To reach a
1 % relative random error on XCH4 measurements, MERLIN
signal processing performs an averaging of data over 50 km along the
satellite trajectory. This article discusses how to process this horizontal
averaging in order to avoid the bias caused by the non-linearity of the
measurement equation and measurements affected by random noise and horizontal
geophysical variability. Three averaging schemes are presented: averaging of
columns of XCH4, averaging of columns of differential absorption
optical depth (DAOD) and averaging of signals. The three schemes are affected
both by statistical and geophysical biases that are discussed and compared,
and correction algorithms are developed for the three schemes. These
algorithms are tested and their biases are compared on modelled scenes from
real satellite data. To achieve the accuracy requirements that are limited to
0.2 % relative systematic error (for a reference value of 1780 ppb), we
recommend performing the averaging of signals corrected from the statistical
bias due to the measurement noise and from the geophysical bias mainly due to
variations of methane optical depth and surface reflectivity along the
averaging track. The proposed method is compliant with the mission relative
systematic error requirements dedicated to averaging algorithms of 0.06 %
(±1 ppb for XCH4 = 1780 ppb) for all tested scenes
and all tested ground reflectivity values.</p
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