328 research outputs found
Refurbishing Voyager 1 & 2 Planetary Radio Astronomy (PRA) Data
Voyager/PRA (Planetary Radio Astronomy) data from digitized tapes archived at
CNES have been reprocessed and recalibrated. The data cover the Jupiter and
Saturn flybys of both Voyager probes. We have also reconstructed
goniopolarimetric datasets (flux and polarization) at full resolution. These
datasets are currently not available to the scientific community, but they are
of primary interest for the analysis of the Cassini data at Saturn, and the
Juno data at Jupiter, as well as for the preparation of the JUICE mission. We
present the first results derived from the re-analysis of this dataset.Comment: Accepted manuscript for PRE8 (Planetary Radio Emission VIII
conference) proceeding
Evaluation of the Mechanical Behaviour of Al2o3 and Al2o3 -Tio2 Coatings Using a Bench Drill
RESUMEN: Las propiedades mecánicas de recubrimientos cerámicos medidas por micro-indentación Vickers y Knoop a partir de las huellas residuales fueron relacionadas con los resultados de perforación usando una broca sin rotación. Tres polvos micrométricos fueron utilizados para elaborar los recubrimientos: el primero de ellos fue de Al2O3 Sulzer-Metco 105 SPFTM , el segundo fue de Al2O3 -13 % en peso de TiO2 Saint Gobain 107TM , y el último fue de Al2O3 -43 % en peso de TiO2 Saint Gobain 109TM. Los recubrimientos fueron elaborados por proyección térmica con llama de oxi-combustible sobre sustratos de acero AISI-SAE 1020, usando una torcha Terodyn
2000 modificada. Los ensayos de perforación fueron realizados con una broca con punta piramidal de carburo de tungsteno montada en un taladro, que aplicó lentamente una fuerza gradual hasta una carga máxima de aproximadamente 100 N y luego la fuerza fue reducida hasta cero, para obtener una curva de hystéresis (fuerza versus profundidad deindentación), siendo la velocidad de carga y descarga de 0.15 mm/s. Los resultados muestran una buena correlación entre las propiedades mecánicas medidas por ensayos de micro-indentación Knoop y los obtenidos a partir de la curva de hystéresis, permitiendo concluir que la dureza y el módulo de Young de los recubrimientos cerámicos elaborados por proyección térmica podrÃan ser determinados a partir de ensayos de perforación.ABSTRACT: The mechanical properties of ceramic coatings measured by Vickers and Knoop microindentation from residual tracks were correlated with the results of indentation depth measured using a non-rotary drill bit. Three micrometric feedstock powders were used to manufacture coatings: the first one was Al2O3 Sulzer-Metco 105 SPFTM, the second one was Al2O3 -13 wt.% TiO2 Saint Gobain 107TM and the last one was Al2O3 -43 wt.% TiO2 Saint Gobain 109TM.
Coatings were elaborated by oxy-fuel flame spraying process onto AISI-SAE 1020 steel
substrates using a modified Terodyn 2000 torch. The drill tests were realized with a pyramidal tungsten carbide drill bit using a instrumented bench drill, which applied slowly an incremental force to a maximal load (approximately 100 N) and then the force was decreased to zero (being the load and unload speed 0.15 mm/s), in order to obtain the hysteresis graphics (Force Vs Indentation Depth). The results show a good relationship between mechanical properties measured by Knoop micro indentation tests and the force vs indentation depth ratio, obtained from hysteresis graphics, allowing to conclude that the hardness and Young’s modulus of thermal sprayed ceramic coatings can be predicted from drilling tests
Measurement of the optical absorption of bulk silicon at cryogenic temperature and the implication for the Einstein Telescope
International audienceWe report in this article on the measurement of the optical absorption of moderately doped crystalline silicon samples at 1550 nm, which is a candidate material for the main optics of the low temperature interferometer of the Einstein Telescope (ET). We observe a nearly constant absorption from room temperature down to cryogenic temperatures for two silicon samples presenting an optical absorption of 0.029 cm −1 and 780 ppm cm −1 , both crystals doped with boron. This is in contradiction to what was assumed previously—a negligible optical absorption at low temperature due to the carrier freezeout. As the main consequence, if the silicon intrinsic absorption can not be lowered , the cross section of the mirror suspension of the ET must be increased to be able to carry away the excess heat generated by the partially absorbed laser beam during the operation of the interferometer
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Effects of classification context on categorization in natural categories
The patterns of classification of borderline instances of eight common taxonomic categories were examined under three different instructional conditions to test two predictions: first, that lack of a specified context contributes to vagueness in categorization, and second, that altering the purpose of classification can lead to greater or lesser dependence on similarity in classification. The instructional conditions contrasted purely pragmatic with more technical/quasi-legal contexts as purposes for classification, and these were compared with a no-context control. The measures of category vagueness were between-subjects disagreement and within-subjects consistency, and the measures of similarity based categorization were category breadth and the correlation of instance categorization probability with mean rated typicality, independently measured in a neutral context. Contrary to predictions, none of the measures of vagueness, reliability, category breadth, or correlation with typicality were generally affected by the instructional setting as a function of pragmatic versus technical purposes. Only one subcondition, in which a situational context was implied in addition to a purposive context, produced a significant change in categorization. Further experiments demonstrated that the effect of context was not increased when participants talked their way through the task, and that a technical context did not elicit more all-or-none categorization than did a pragmatic context. These findings place an important boundary condition on the effects of instructional context on conceptual categorization
Radio Broadcasts from Superconducting Strings
Superconducting cosmic strings can give transient electromagnetic signatures
that we argue are most evident at radio frequencies. We investigate the three
different kinds of radio bursts from cusps, kinks, and kink-kink collisions on
superconducting strings. We find that the event rate is dominated by kink
bursts in a range of parameters that are of observational interest, and can be
quite high (several a day at 1 Jy flux) for a canonical set of parameters. In
the absence of events, the search for radio transients can place stringent
constraints on superconducting cosmic strings.Comment: 11 pages, 3 figure
Variant Salmonella Genomic Island 1 Antibiotic Resistance Gene Cluster in Salmonella enterica Serovar Albany
Salmonella genomic island 1 (SGI1) contains an antibiotic resistance gene cluster and has been previously identified in multidrug-resistant Salmonella enterica serovars Typhimurium DT104, Agona, and Paratyphi B. We identified a variant SGI1 antibiotic-resistance gene cluster in a multidrug-resistant strain of S. enterica serovar Albany isolated from food fish from Thailand and imported to France. In this strain, the streptomycin resistance aadA2 gene cassette in one of the SGI1 integrons was replaced by a dfrA1 gene cassette, conferring resistance to trimethoprim and an open reading frame of unknown function. Thus, this serovar Albany strain represents the fourth S. enterica serovar in which SGI1 has been identified and the first SGI1 example where gene cassette replacement took place in one of its integron structures. The antibiotic resistance gene cluster of serovar Albany strain 7205.00 constitutes a new SGI1 variant; we propose a name of SGI1-F
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