The 2011 October Draconids Outburst. II. Meteoroid Chemical Abundances from Fireball Spectroscopy

On October 8, 2011 the Earth crossed dust trails ejected from comet 21P/Giacobini-Zinner in the late 19th and early 20th Century. This gave rise to an outburst in the activity of the October Draconid meteor shower, and an international team was organized to analyze this event. The SPanish Meteor Network (SPMN) joined this initiative and recorded the October Draconids by means of low light level CCD cameras. In addition, spectroscopic observations were carried out. Tens of multi-station meteor trails were recorded, including an extraordinarily bright October Draconid fireball (absolute mag. -10.5) that was simultaneously imaged from three SPMN meteor ob-serving stations located in Andalusia. Its spectrum was obtained, showing a clear evolution in the relative intensity of emission lines as the fireball penetrated deeper into the atmosphere. Here we focus on the analysis of this remarkable spectrum, but also discuss the atmospheric trajectory, atmospheric penetration, and orbital data computed for this bolide which was probably released during 21P/Giacobini-Zinner return to perihelion in 1907. The spectrum is discussed together with the tensile strength for the October Draconid meteoroids. The chemical profile evolution of the main rocky elements for this extremely bright bolide is compared with the elemental abundances obtained for 5 October Draconid fireballs also recorded during our spectroscopic campaign but observed only at a single station. Significant chemical heterogeneity between the small meteoroids is found as we should expect for cometary aggregates being formed by diverse dust components.Comment: Manuscript in press in Monthly Notices of the Royal Astronomical Society. Accepted for publication in MNRAS on April 28th, 2013 Manuscript Pages: 28 Tables: 5 Figures: 12. Manuscript associated: "The 2011 October Draconids outburst. I. Orbital elements, meteoroid fluxes and 21P/Giacobini-Zinner delivered mass to Earth" by Trigo-Rodriguez et al. is also in press in the same journa

Mechanical Characterization of Tungsten-Titanium-Lanthana alloy: Influence of Temperature and Atmosphere

The target is to evaluate the mechanical behavior of Ti and La2O3 dispersed W alloy, processed by HIP and compare it with a reference pure-W. Tests were performed in both oxidant (air) and inert (vacuum) atmosphere in a temperature range from -196 to 1200 °C

Comportamiento mecánico de la aleación W+1%Y2O3 en función de la atmósfera y la temperatura

Mediante ensayos de flexión en tres puntos se compara y evalúa el comportamiento mecánico de la aleación W- 1wt%Y2O3 con el W puro fabricados ambos mediante HIP. Se ha obtenido la tenacidad de fractura, la resistencia a flexión y el límite elástico en atmósfera oxidante y de vacío en un intervalo de temperaturas comprendido entre -196 ºC, ensayos de inmersión en nitrógeno líquido, y 1200 ºC. Previamente, se ha medido la densidad, la dureza mediante ensayos Vickers y el módulo de elasticidad dinámico de los materiales. Además, la dureza y el módulo de elasticidad se han comparado con los obtenidos mediante ensayos instrumentados de nanoindentación. Finalmente se ha realizado un pequeño estudio de las superficies de fractura de las muestras ensayadas mediante microscopía electrónica de barrido para poder relacionar el modo de rotura de los materiales y las propiedades mecánicas macroscópicas con los micromecanismos de fallo involucrados en función de la temperatura

Mechanical characterisation of tungsten-1wt.% yttrium oxide as a function of temperature and atmosphere

This study evaluates the mechanical behaviour of an Y2O3-dispersed tungsten (W) alloy and compares it to a pure W reference material. Both materials were processed via mechanical alloying (MA) and subsequent hot isostatic pressing (HIP). We performed non-standard three-point bending (TPB) tests in both an oxidising atmosphere and vacuum across a temperature range from 77 K, obtained via immersion in liquid nitrogen, to 1473 K to determine the mechanical strength, yield strength and fracture toughness. This research aims to evaluate how the mechanical behaviour of the alloy is affected by oxides formed within the material at high temperatures, primarily from 873 K, when the materials undergo a massive thermal degradation. The results indicate that the alloy is brittle to a high temperature (1473 K) under both atmospheres and that the mechanical properties degrade significantly above 873 K. We also used Vickers microhardness tests and the dynamic modulus by impulse excitation technique (IET) to determine the elastic modulus at room temperature. Moreover, we performed nanoindentation tests to determine the effect of size on the hardness and elastic modulus; however, no significant differences were found. Additionally, we calculated the relative density of the samples to assess the porosity of the alloy. Finally, we analysed the microstructure and fracture surfaces of the tested materials via field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). In this way, the relationship between the macroscopic mechanical properties and micromechanisms of failure could be determined based on the temperature and oxides forme

High quality optically active and integrable EuOOH films prepared by pulsed laser deposition

Rare-earth (RE)-Oxygen-Hydrogen compounds are versatile materials whose composition and properties can be significantly varied by changing the relative O and H contents. Among them hydrides and oxyhydrides have been thoroughly investigated due to its photochromic properties. Instead, research of RE-hydroxides and oxyhydroxides (RE-OH and RE-OOH) is scarce although they show promising properties as light emitters. However, their use and integration in solid state devices have been hindered so far because their usual chemical synthesis routes yield materials in bulk or powder configurations. In this work we demonstrate a physical deposition route based on pulsed laser deposition that results in the unprecedented preparation of high-quality Eu oxyhydroxide (EuOOH) thin films. The synthetized EuOOH films show a well-defined monoclinic structure, are optically active and show a robust red emission related to the intra-f transitions of the Eu3+ ions. The excellent quality of these crystalline films has allowed us to obtain relevant properties of the monoclinic EuOOH phase not previously reported such as its refractive index and its Raman spectrum, including the identification of the characteristic phonon modes. These novel EuOOH films have been prepared both on Si and fused silica substrates, and thus are ready for potential integration in solid state optoelectronic components and devicesThis work was funded by the Spanish Research Agency (AEI, Ministry of Research and Innovation) and the European Regional Development Fund (ERDF) under grants RTI2018-096498-B-I00, RTI2018-101020-B-I00, RTI2018-096918-B-C41 and PID2021-123190OB-I00; by the CSIC (PIE-202050E195 and project 2021AEP128IO); by the Regional Government of Madrid through TECHNOFUSION(III)CM ´ (S2018/EMT-4437); and by Comunidad de Madrid (Spain) multiannual agreement with UC3M, “Excelencia para el Profesorado Universitario” (EPUC3M14) - Fifth regional research plan 2016-2020. The work of A. Cano was partially supported by the Autonomous Community of Madrid and the European Social Fund (PEJD-2019-PRE/TIC-16082

Las empresas de ingeniería en la construcción industrial: evolución y futuro

Firstly, this paper sets out a short analysis on the evolution of the spanish industrial plants construction sub-sector. Then, the current main characteristics of the most important companies in the world, working in this sub-sector, are presented. This part of the paper is structured following the life-cycle of the construction project, from the plant s conceptual engineering to its construction, transfer and operation; examples and real data of some of the most relevant international engineering firms, as can be Bechtel and Fluor, are included. Finally, on the one hand, and based in the previous analysis, the paper summarizes the main issues of these companies that constitute competitive advantages to analyze and follow or adapt by other firms of the same type; and, on the other hand, the main potential issues of the future evolution of the industrial plants construction sub-sector are included.El presente artículo expone, en primer lugar, un breve análisis sobre la evolución del sub-sector español de la construcción de plantas industriales y sistemas similares. Tras ello se incluye un repaso de las principales características actuales de las empresas más importantes del mundo en el campo de la construcción industrial, siguiendo el ciclo de vida del proyecto de construcción, desde la ingeniería conceptual hasta la construcción, transferencia y explotación de la planta; se incluyen ejemplos y datos reales de algunas de las empresas de mayor importancia en el panorama internacional, como es el caso de Bechtel y Fluor. Finalmente, por un lado, y en función de este análisis de las grandes empresas de ingeniería en este campo, se han resumido los principales aspectos de estas organizaciones que suponen ventajas competitivas a analizar y seguir por otras empresas de este tipo; y por otro, se han tratado de anticipar los posibles aspectos esenciales de la evolución futura de este sub-sector, en función de la evolución del mismo hasta la fecha

Neoker Single Crystal Alumina Fibers as reinforcement in Al-based MMC: first steps

α-Al2O3 whiskers are good candidates for use as strengtheners in advanced composites, specifically, single crystal -Al2O3 whiskers grown with c-axis orientation, because of their favorable fracture strength, stiffness, and creep resistance, even at high temperatures are optimum reinforces. Very few methods are currently available to obtain single-crystal α-Al2O3 whiskers, and these methods were too complex and expensive for use on an industrial scale. A novel method for obtaining c-axis alumina single-crystal whiskers (developed at the Institute of Ceramic Materials of Galicia) has been scaled-up to industrial production by Neoker, a Spin-Off of the of the University of Santiago de Compostela, Spain. The technology for the production of the whiskers involves the reaction between aluminum and powdered silica in Ar atmospheres containing metal vapors. Aluminum is the most popular matrix for the metal matrix composites (MMCs). The Al alloys are quite attractive due to their low density, their capability to be strengthened by precipitation, their good corrosion resistance, high thermal and electrical conductivity, and their high damping capacity. The reinforcement in AMCs could be in the form of continuous/discontinuous whiskers, whisker or particulates, in volume fractions ranging from a few percent to 70%. Properties of AMCs can be tailored to the demands of different industrial applications by suitable combinations of matrix, reinforcement and processing route. The composites studied in the present work were prepared by infiltration processes where the reinforcements were pressed into a preform that was then infiltrated by the molten Al allo