7,819 research outputs found
Structural and optical properties of compensated microcrystalline silicon films
Boron-doped microcrystalline silicon films were deposited in a plasma enhanced chemical vapor deposition (PECVD) system using silane (SiH4) diluted in hydrogen, and diborane (B2H6) as a dopant gas. The effects of the Boron concentration on the optical and structural properties were investigated by the constant-photocurrent method (CPM) and atomic force microscopy (AFM) measurements. The variations in the optical constants (refractive index, absorption coefficient and optical gap) as a function of wavelength were carried out from the optical transmission and CPM spectra. By increasing the doping level, a systematic increase in the absorption coefficient spectra in the low-energy region between 0.7 - 1.2 eV was observed. It was found that the increase of Boron concentration in the samples results in changes of the grain size. Correlations between optical properties and the density of states (DOS) were also studied.Fil: Dussan, A.. Universidad Nacional de Colombia; ColombiaFil: Koropecki, Roberto Roman. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Arce, Roberto Delio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Schmidt, Javier Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin
A Bubbling Nearby Molecular Cloud: COMPLETE Shells in Perseus
We present a study on the shells (and bubbles) in the Perseus molecular cloud
using the COMPLETE survey large-scale 12CO(1-0) and 13CO(1-0) maps. The twelve
shells reported here are spread throughout most of the Perseus cloud and have
circular or arc-like morphologies with a range in radius of about 0.1 to 3 pc.
Most of them have not been detected before most likely as maps of the region
lacked the coverage and resolution needed to distinguish them. The majority of
the shells are coincident with infrared nebulosity of similar shape and have a
candidate powering source near the center. We suggest they are formed by the
interaction of spherical or very wide-angle winds powered by young stars inside
or near the Perseus molecular cloud -a cloud that is commonly considered to be
mostly forming low-mass stars. Two of the twelve shells are powered by
high-mass stars close to the cloud, while the others appear to be powered by
low or intermediate mass stars in the cloud. We argue that winds with a mass
loss rate of about 10^-8 to 10^-6 M_sun/yr are required to produce the observed
shells. Our estimates indicate that the energy input rate from these stellar
winds is similar to the turbulence dissipation rate. We conclude that in
Perseus the total energy input from both collimated protostellar outflows and
powerful spherical winds from young stars is sufficient to maintain the
turbulence in the molecular cloud. Large scale molecular line and IR continuum
maps of a sample of clouds will help determine the frequency of this phenomenon
in other star forming regions.Comment: 48 pages in total: 16 pages of text and references; 2 pages of
tables; 30 figures (one page per figure). Accepted for publication in the
Astrophysical Journa
Smart and networking underwater robots in cooperation meshes : the swarms ECSEL : H2020 project
The work presented on this paper is aimed to explain the role that
unmanned underwater vehicles (AUVs/ROVs) plays in the ECSEL-H2020 SWARMS
project. The main goal of the project is to reduce the operational cost and increase
the safety of tasks assigned to divers in these operations. This will be achieved
enabling the AUVs/ROVs to work in a cooperative mesh. The challenge is to design
and develop an integrated platform (a set of Software/Hardware components),
incorporated into the current generation of underwater vehicles in order to
improve autonomy, cooperation, robustness, cost-effectiveness, and reliability of
the offshore operations. The first demonstration of the project will be performed at
PLOCAN (Oceanic Platform of the Canary Islands) where these technologies will be
validated on its first stage.Peer Reviewe
Negotiating agricultural development: entanglements of bureaucrats and rural producers in Western Mexico.
Configuración canónica de la potestad de régimen del obispo diocesano del concilio vaticano I al C.I.C. de 1983
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