1,585 research outputs found
Paper Session III-B - Space Station On-Orbit Assembly and Operation
The United States and its international partners are well on the way to developing Space Station Freedom which will be a very large orbiting facility with many capabilities for conducting space operations. Adjustments in the program content and station design have been implemented as a result of the recent restructure activity. This paper addresses the assembly and operations aspects of SSF. Assembly is achieved by sequential shuttle launches which carry portions of the station building the capability through the Manned Tended Capability and then on to Permanent Manned Capability. The pre-integrated truss segment resulting from the program restructure activity is shown and assembly techniques using the orbiter described. Both pay load and station operations are examined. The pay load operations include the conduct of materials processing and life science missions. These rely heavily on the microgravity capability of the Space Station. Station operations examined include EVA for assembly and maintenance and reboost techniques
Improved thermal isolation of silicon suspended platforms for an all-silicon thermoelectric microgenerator based on large scale integration of Si nanowires as thermoelectric material
Special suspended micro-platforms have been designed as a part of silicon compatible planar thermoelectric microgenerators. Bottom-up grown silicon nanowires are going to bridge in the future such platforms to the surrounding silicon bulk rim. They will act as thermoelectric material thus configuring an all-silicon thermoelectric device. In the new platform design other additional bridging elements (usually auxiliary support silicon beams) are substituted by low conductance thin film dielectric membranes in order to maximize the temperature difference developed between both areas. These membranes follow a sieve-like design that allows fabricating them with a short additional wet anisotropic etch step. © Published under licence by IOP Publishing Ltd.Peer ReviewedPostprint (published version
Molecular Line Observations of the Small Protostellar Group L1251B
We present molecular line observations of L1251B, a small group of pre- and
protostellar objects, and its immediate environment in the dense C18O core
L1251E. These data are complementary to near-infrared, submillimeter and
millimeter continuum observations reported by Lee et al. (2006, ApJ, 648, 491;
Paper I). The single-dish data of L1251B described here show very complex
kinematics including infall, rotation and outflow motions, and the
interferometer data reveal these in greater detail. Interferometer data of N2H+
1-0 suggest a very rapidly rotating flattened envelope between two young
stellar objects, IRS1 and IRS2. Also, interferometer data of CO 2-1 resolve the
outflow associated with L1251B seen in single-dish maps into a few narrow and
compact components. Furthermore, the high resolution data support recent
theoretical studies of molecular depletions and enhancements that accompany the
formation of protostars within dense cores. Beyond L1251B, single-dish data are
also presented of a dense core located ~150" to the east that, in Paper I, was
detected at 850 micron but has no associated point sources at near- and
mid-infrared wavelengths. The relative brightness between molecules, which have
different chemical timescales, suggests it is less chemically evolved than
L1251B. This core may be a site for future star formation, however, since line
profiles of HCO+, CS, and HCN show asymmetry with a stronger blue peak, which
is interpreted as an infall signature.Comment: 46 pages, 18 figures. Accepted for publication in Ap
A proto brown dwarf candidate in Taurus
Aims. We search for brown dwarfs at the Class 0/I evolutionary stage, or proto brown dwarfs.
Methods. We present a multi wavelength study, ranging from optical at 0.8 ÎŒm to radio wavelengths at 6 cm, of a cool, very faint, and red multiple object, SSTB213 J041757, detected by Spitzer toward the Barnard 213 dark cloud, in Taurus.
Results. The SED of SSTB213 J041757 displays a clear excess at long wavelengths resembling that of a Class I object. The mid-IR source has two possible counterparts, A and B, in the near-IR and optical images, and the 350 ÎŒm observations detect clear extended emission, presumably from an envelope around the two sources. The position of A & B in the (Icâ J) versus (J â [3.6]) colour-colour diagram is consistent with them being Galactic sources and not extragalactic contaminants. A proper-motion study confirms this result for A, while it is inconclusive for B. The temperature and mass of the two possible central objects, according to COND evolutionary models, range between 1550â1750 K and 3â4 M_(Jupiter), and 950â1300 K and 1â2 M_(Jupiter), for A and B, respectively. The integrated SED provides bolometric temperatures and luminosities of 280 K and 0.0034 L_â, assuming that the emission at wavelengths > 5 ÎŒm is associated with component A, and 150 K and 0.0033 L_â, assuming that the emission at wavelengths > 5 ÎŒm is associated with component B, which would imply the SSTB213 J041757 object has a luminosity well below the luminosity of other very low luminosity objects discovered up to date.
Conclusions. With these characteristics, SSTB213 J041757 seems to be a promising, and perhaps double, proto brown dwarf candidate
Impact of the application of monosilicic acid to grapevine (Vitis vinifera L.) on the chemical composition of young red Mencia wines
Impact of applying monosilicic acid to grapevines during ripening on chemical composition of MencĂa red wines in an area where fungal diseases during summer are common was examined. The foliar application of monosilicic acid to grapevines led to a less oxidized wine, with lower levels of acetic acid, acetaldehyde, ethyl acetate and diacethyl; this should be considered as positive from a sensory point of view. Wines made with silicon-treated grapes also contained lower levels of gluconic acid and glycerol, which are chemical markers of wines made with botrytized grapes, as well as higher contents of total phenols, anthocyanins and tannins. Furthermore, the contents of several mid-chain alcohols were higher (p < 0.05) in wines made with grapes from silicon-treated plantsThe authors gratefully acknowledge the financial support by the FEDER/Spanish Ministry of Science, Innovation, and Universities Project: RTI2018-096268-B-I00. This work was partially supported by Comunidad de Madrid (Spain) and Structural Funds 2014â2020 (ERDF and ESF) (Project AGRISOST-CM S2018/BAA-4330
Diagnosis and numerical simulations of a heavy rain event in the Western Mediterranean Basin
International audienceThe heavy rain event of November 2001 in the western Mediterranean area was synoptically characterized by the presence of a long-lived Omega blocking geopotential pattern. A set of mesoscale numerical simulations using MM5 is performed to investigate the mechanisms responsible for the convection development through several output diagnosis. A potential vorticity evolution showed how dry air masses were extruded from the stratospheric levels promoting strong cyclonic circulation at all levels. Moreover, a deep vertical column of high relative humidity over the Algerian coastline maintained the few and geographically confined convective cells responsible for the heavy precipitation. Mesoscale environment parameters indicated enhanced conditional instability through a deep troposphere layer. Also, strong vertical wind shear values, higher than 50 ms?1 over the troposphere, were derived, indicating enough strength to promote necessary conditions to organize and keep mesoscale convective structures
Springtime connections between the large-scale sea-level pressure field and gust wind speed over Iberia and the Balearics
This paper investigates, by means of Singular Value Decomposition analysis, the springtime relationships between the mean sea-level pressure field over the North Atlantic and the regional wind gusts over the Iberian Peninsula, identifying the main atmospheric circulation patterns linked to gust wind speed anomaly configurations. The statistical significance of the obtained modes is investigated by means of Monte Carlo approach. The analysis highlighted that the covariability is dominated by two main large-scale features of the atmospheric circulation over the North Atlantic. The first mode relates to Iberian gust wind speeds to the Scandinavian pattern (SCAND), linking the large-scale pattern to above-normal wind gusts. The second covariability mode, associated with the North Atlantic Oscillation (NAO) pattern, correlates with maximum wind speeds over Iberia. An enhanced spring NAO pattern is related to positive (negative) wind gust correlations over northern (southern) Iberia. To find true relationships between large-scale atmospheric field and the gust wind speeds, composite maps were built up to give an average atmospheric circulation associated with coherent wind gust variability over Iberia
A search for pre- and proto-brown dwarfs in the dark cloud Barnard 30 with ALMA
In this work we present ALMA continuum observations at 880 m of 30
sub-mm cores previously identified with APEX/LABOCA at 870m in the Barnard
30 cloud. The main goal is to characterize the youngest and lowest mass
population in the cloud. As a result, we report the detection of five (out of
30) spatially unresolved sources with ALMA, with estimated masses between 0.9
and 67 M. From these five sources, only two show gas emission. The
analysis of multi-wavelength photometry from these two objects, namely B30-LB14
and B30-LB19, is consistent with one Class II- and one Class I low-mass stellar
object, respectively. The gas emission is consistent with a rotating disk in
the case of B30-LB14, and with an oblate rotating envelope with infall
signatures in the case of LB19. The remaining three ALMA detections do not have
infrared counterparts and can be classified as either deeply embedded objects
or as starless cores if B30 members. In the former case, two of them (LB08 and
LB31) show internal luminosity upper limits consistent with Very Low Luminosity
objects, while we do not have enough information for LB10. In the starless core
scenario, and taking into account the estimated masses from ALMA and the
APEX/LABOCA cores, we estimate final masses for the central objects in the
substellar domain, so they could be classified as pre-BD core candidates.Comment: Published in A&
Iberian autumnal precipitation characterization through observed, simulated and reanalysed data
International audienceA 44-year (1958?2001) homogeneous Mediterranean high-resolution atmospheric database was generated through dynamical downscaling within the HIPOCAS Project framework. The present work attempts to provide a validation of the monthly 41-autumnal (1961?2001) HIPOCAS precipitation over the Iberian Peninsula, being also provided an evaluation of its improvement versus current global reanalysis data sets. A statistical comparative analysis between observed, HIPOCAS and global reanalyses precipitation data sets was carried out, highlighting the noticeable agreement existing between the observed and the HIPOCAS precipitation data sets in terms of not only time and spatial distribution, but also in terms of total amount of precipitation. A principal component analysis is carried out showing that the patterns derived from the HIPOCAS data largely capture the main characteristics of the studied field. Moreover, it is worth to note that the HIPOCAS patterns reproduce accurately the observed regional characteristics linked to the main orographic features of the study domain
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