527 research outputs found
Recommended from our members
From stardust to planets: FT-IR spectroscopy of fine-grained planetary materials
Recommended from our members
Infrared spectroscopy of circumstellar dust: signs of differentiated materials?
Mid-infrared absorption spectra of powdered achondrites are compared with the astronomical spectra of dust around young, evolving stars, to find evidence (or not) of dust formed in collisional cascades of material from planetesimals
Cost characteristics of tilt-rotor, conventional air and high speed rail short-haul intercity passenger service
The cost analysis done to support an assessment of the potential for a small tilt-rotor aircraft to operate in short-haul intercity passenger service is described in detail. Anticipated costs of tilt-rotor air service were compared to the costs of two alternatives: conventional air and high speed rail (HSR). Costs were developed for corridor service, varying key market characteristics including distance, passenger volumes, and minimum frequency standards. The resulting cost vs output information can then be used to compare modal costs for essentially identical service quality and passenger volume or for different service levels and volumes for each mode, as appropriate. Extensive sensitivity analyses are performed. The cost-output features of these technologies are compared. Tilt-rotor is very attractive compared to HSR in terms of costs over the entire range of volume. It also has costs not dramatically different from conventional air, but tilt-rotor costs are generally higher. Thus some of its other advantages, such as the VTOL capability, must offset the cost disadvantage for it to be a preferred or competitive mode in any given market. These issues are addressed in the companion report which considers strategies for tilt-rotor development in commercial air service
Recommended from our members
Mid-infrared spectroscopy of matrix materials from chondrites: first heating experiments
Recommended from our members
FT-IR microanalysis of mineral separates from primitive meteorites: techniques, problems and solutions
From the Introduction: We compared several methods of infrared micro spectroscopy using an FT-IR microscope and workbench. This is part of a project to assemble a database of infrared and optical spectra from mineral separates from meteorites, for comparison with astronomical data. Since we usually have to work with small amounts of material (original grain sizes often <50 m), special sample preparation and analytical procedures
have to be applied
Recommended from our members
Infrared spectroscopy of extraterrestrial material: comparison with astronomical spectra of dust
Infrared spectra of components (CAI, matrix etc.) from type 3 carbonacous chondrites (Allende, Ornans, Vigarano) are compared with infrared spectra from astronomical objects (comets, zodiacal light, circumstellar disks and others)
Recommended from our members
Dust from collisions: mid-infrared absorbance spectroscopy of Martian meteorites
Mid-infrared transmission/absorbance spectra of a representative range of martian meteorites are presented. The data is used for mineralogical bulk studies, but also for the comparison with astronomical dust spectra
Applying for jobs: Does ALMP participation help?
This paper calculates the impact of Active Labour Market Programmes through the use of three new indicators measuring the application performance of the unemployed. These indicators can be measured repeatedly and therefore allow the usage of Panel Regression methods, cancelling out any unobserved individual heterogeneity. To implement the new approach, data on 30,000 applications has been collected. Using this data, a large positive effect for unemployed with a long term unemployment forecast was estimated. For unemployed without such a forecast, the effect is much smaller. The paper also shows that the new evaluation approach fulfils the requirements of a good controlling instrument: It is accurate, detailed, non-intrusive, inexpensive and therefore easy to keep up to date, easy to understand and communicate.Evaluation, treatment effect, active labour market program, job search
Recommended from our members
Mid-infrared reflectance spectroscopy of calcium-aluminium-rich inclusions to identify primitive near Earth asteroids
The recent availability of mid-IR spectroscopy from space telescopes has led to studies attempting to characterise the composition of near Earth asteroids (NEAs) by comparison to spectroscopic observations of meteorites in the laboratory (e.g. [1, 2]). Mid-IR of carbonaceous chondrite meteorites has also recently been in focus to identify primitive asteroids and the aqueous alteration processes occurring on them [3]. Of special interest among the components of carbonaceous chondrites are the refractory calcium-aluminium-rich inclusions (CAIs) because they are formed very early on in the solar system. We have gathered reflectance spectra in the 2.5-16.0 μm range of the phases (spinel, olivine, melilite, pyroxene, etc.) in CAI sections of meteorites Allende (CV3.3), Vigarano (CV3.3) and Ornans (CO3.3) with a Perkin Elmer AutoIMAGE FTIR microscope, and compared them to mid-IR spectra of several NEA targets (253 Mathilde, 243 Ida, 1917 Cuyo, and the target of OSIRIS-Rex mission 101955 Bennu) of the Spitzer Space Telescope's Infrared Spectrometer (IRS [4]). Spectra from Spitzer were extracted with an optimal extraction method [5] and corrected with a near earth thermal model [6]. Reflectance spectra obtained from the CAIs were compared to spectra in the Keck/NASA RELAB database [7]. Overall, we see some features on the surfaces of the observed asteroids that may correspond to the pristine CAIs from the chondrites, though identification of these features is not easy.
References: [1] Emery, J. P. et al. (2006) Icarus, 182, 496-512. [2] Lim, L. F. et al. (2011) Icarus, 213, 510-523. [3] Trigo-Rodriguez, J. M. et al. (2014) Mon. Not. R. Astron. Soc. 437, 227-240. [4] Houck, J. R. et al. (2004) Astron. Phy. J. Suppl. 154, 18-24. [5] Lebouteiller, V. et al. (2010) Publ. Astron. Soc. Pac., 122.888, 231-240. [6] Harris, A. W. (1998) Icarus 131, 291-301. [7] Pieters, C. M., and Hiroi, T. (2004). Lunar Planet. Sci. XXXV, # 1720
- …