Mascarenhas L.A.B.,SENAI CIMATEC |
Gomes J.O.,ITA CCM |
Barbosa C.,CAB |
Nogueira T.B.,SENAI CIMATEC |
Portela A.T.,SENAI CIMATEC
Journal of the Brazilian Society of Mechanical Sciences and Engineering | Year: 2015
The valve and valve seat work together to ensure the entry of air and combustible material, the output of combustion gases and the sealing function of the compression and combustion process. The valve is the most demanding component in high efficiency engines. To work efficiently and produce low emissions, special materials are needed. Extreme temperatures of the exhaust gases, high velocities of valves and high pressure are just some of the conditions that cause wear on the valves. The materials used in production must have good workability, low wear, good mechanical strength and good fatigue and corrosion resistance at high temperature. CCM/ITA and SENAI CIMATEC have jointly developed a workbench to simulate the durability of valves and valve seats and to enable analysis of wear resistance and by testing different parameter values. Using this workbench, some materials were tested to determine whether they can be used at high temperatures, as will be necessary in the next generation of engines. Detachments from the seat material (SAE 4340) were observed in the tests, and the detached material adhered to the valve. This phenomenon significantly increases the surface roughness of the components, and it may lead to loss of function. Thus, the tested valve material (SAE EV12 21-2 N) was more resistant to wear than the seat material. © 2015, The Brazilian Society of Mechanical Sciences and Engineering.
Daly A.M.,University of Valladolid |
Bermudez C.,University of Valladolid |
Lopez A.,CAB |
Tercero B.,CAB |
And 4 more authors.
Astrophysical Journal | Year: 2013
Ethyl cyanide, CH3CH2CN, is an important interstellar molecule with a very dense rotational-vibrational spectrum. On the basis of new laboratory data in the range of 17-605 GHz and ab initio calculations, two new vibrational states, ν12 and ν20, have been detected in molecular clouds of Orion. Laboratory data consist of Stark spectroscopy (17-110 GHz) and frequency-modulated spectrometers (GEM laboratory in Valladolid: 17-170, 270-360 GHz; Toyama: 26-200 GHz; Emory: 200-240 GHz; Ohio State: 258-368 GHz; and JPL: 270-318, 395-605 GHz). More than 700 distinct lines of each species were measured in J up to 71 and in Ka up to 25. The states were fitted with Watson's S-reduction Hamiltonian. The two new states have been identified in the interstellar medium toward the Orion Nebula (Orion KL). The ground state, the isotopologues of CH3CH2CN, and the vibrationally excited states have been fitted to obtain column densities and to derive vibrational temperatures. All together, ethyl cyanide is responsible for more than 2000 lines in the observed frequency range of 80-280 GHz. © 2013. The American Astronomical Society. All rights reserved.
Swinyard B.,University College London |
Swinyard B.,Rutherford Appleton Laboratory |
Tinetti G.,University College London |
Eccleston P.,Rutherford Appleton Laboratory |
And 31 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012
The Exoplanet Characterisation Observatory (EChO) is a space mission dedicated to undertaking spectroscopy of transiting exoplanets over the widest wavelength range possible. It is based around a highly stable space platform with a 1.2 m class telescope. The mission is currently being studied by ESA in the context of a medium class mission within the Cosmic Vision programme for launch post 2020. The payload suite is required to provide simultaneous coverage from the visible to the mid-infrared and must be highly stable and effectively operate as a single instrument. In this paper we describe the integrated spectrometer payload design for EChO which will cover the 0.4 to 16 micron wavelength band. The instrumentation is subdivided into 5 channels (Visible/Near Infrared, Short Wave InfraRed, 2 x Mid Wave InfraRed; Long Wave InfraRed) with a common set of optics spectrally dividing the input beam via dichroics. We discuss the significant design issues for the payload and the detailed technical trade-offs that we are undertaking to produce a payload for EChO that can be built within the mission and programme constraints and yet which will meet the exacting scientific performance required to undertake transit spectroscopy. © 2012 SPIE.
Cernicharo J.,CAB |
Marcelino N.,NRAO |
Roueff E.,French National Center for Scientific Research |
Gerin M.,Ecole Normale Superieure de Paris |
And 2 more authors.
Astrophysical Journal Letters | Year: 2012
We report on the discovery of the methoxy radical (CH3O) toward the cold and dense core B1-b based on the observation, with the IRAM 30m radio telescope, of several lines at 3 and 2mm wavelengths. Besides this new molecular species we also report on the detection of many lines arising from methyl mercaptan (CH3SH), formic acid (HCOOH), propynal (HCCCHO), acetaldehyde (CH3CHO), dimethyl ether (CH3OCH 3), methyl formate (CH3OCOH), and the formyl radical (HCO). The column density of all these species is ≃1012 cm -2, corresponding to abundances of ≃10-11. The similarity in abundances for all these species strongly suggest that they are formed on the surface of dust grains and ejected to the gas phase through non-thermal desorption processes, most likely cosmic rays or secondary photons. Nevertheless, laboratory experiments indicate that the CH3O isomer released to the gas phase is CH2OH rather than the methoxy one. Possible gas-phase formation routes to CH3O from OH and methanol are discussed. © 2012. The American Astronomical Society. All rights reserved.
Tinetti G.,University College London |
Beaulieu J.P.,CNRS Paris Institute of Astrophysics |
Henning T.,Max Planck Institute for Astronomy |
Meyer M.,ETH Zurich |
And 131 more authors.
Experimental Astronomy | Year: 2012
A dedicated mission to investigate exoplanetary atmospheres represents a major milestone in our quest to understand our place in the universe by placing our Solar System in context and by addressing the suitability of planets for the presence of life. EChO-the Exoplanet Characterisation Observatory-is a mission concept specifically geared for this purpose. EChO will provide simultaneous, multi-wavelength spectroscopic observations on a stable platform that will allow very long exposures. The use of passive cooling, few moving parts and well established technology gives a low-risk and potentially long-lived mission. EChO will build on observations by Hubble, Spitzer and ground-based telescopes, which discovered the first molecules and atoms in exoplanetary atmospheres. However, EChO's configuration and specifications are designed to study a number of systems in a consistent manner that will eliminate the ambiguities affecting prior observations. EChO will simultaneously observe a broad enough spectral region-from the visible to the mid-infrared-to constrain from one single spectrum the temperature structure of the atmosphere, the abundances of the major carbon and oxygen bearing species, the expected photochemically-produced species and magnetospheric signatures. The spectral range and resolution are tailored to separate bands belonging to up to 30 molecules and retrieve the composition and temperature structure of planetary atmospheres. The target list for EChO includes planets ranging from Jupiter-sized with equilibrium temperatures Teq up to 2,000 K, to those of a few Earth masses, with Teq \u223c 300 K. The list will include planets with no Solar System analog, such as the recently discovered planets GJ1214b, whose density lies between that of terrestrial and gaseous planets, or the rocky-iron planet 55 Cnc e, with day-side temperature close to 3,000 K. As the number of detected exoplanets is growing rapidly each year, and the mass and radius of those detected steadily decreases, the target list will be constantly adjusted to include the most interesting systems. We have baselined a dispersive spectrograph design covering continuously the 0. 4-16 μm spectral range in 6 channels (1 in the visible, 5 in the InfraRed), which allows the spectral resolution to be adapted from several tens to several hundreds, depending on the target brightness. The instrument will be mounted behind a 1. 5 m class telescope, passively cooled to 50 K, with the instrument structure and optics passively cooled to \u223c45 K. EChO will be placed in a grand halo orbit around L2. This orbit, in combination with an optimised thermal shield design, provides a highly stable thermal environment and a high degree of visibility of the sky to observe repeatedly several tens of targets over the year. Both the baseline and alternative designs have been evaluated and no critical items with Technology Readiness Level (TRL) less than 4-5 have been identified. We have also undertaken a first-order cost and development plan analysis and find that EChO is easily compatible with the ESA M-class mission framework. © 2012 Springer Science+Business Media B.V.