Fabry-Perot (FP) sensors like other Fiber Optic (FO) sensors may be of particular interest for in pile experiments in MTR with little room available thanks to their compact size. Light weight also reduces gamma heating hence limiting the thermal effect. Different physical parameters such as temperature, strain, displacement, vibration, pressure, or refractive index may be sensed through the measurement of the optical path length difference in the cavity. We have developed a Fabry-Perot extensometer able to operate at high temperature (up to 400°C), under a high level of radiation (neutron and gamma flux). The measurement based on interferometry is largely insensitive to radiation induced attenuation (RIA) thanks to the wavelength encoding of the useful signal, but for such high fluence as encountered in a reactor core, a special rad-hard fiber is needed. Operating in the wavelength domain around 1ím remains preferable to minimize the impact of irradiation. Moreover, fast neutron radiation is expected to change the structure of the fiber and possibly others materials in the transducer. Then, we revised the basic scheme of Extrinsic Fabry-Perot Interferometer (EFPI) so that the effects of compaction remain limited. Tests under mixed neutron and gamma irradiation permitted to verify the general behavior and particularly the low drift with radiation induced compaction (RIC). Also, two types of tests have been conducted to verify the accuracy at high temperature. The first ones are “measurements” of thermal dilatation of materials: the sensor is fixed on a sample and knowing its thermal expansion, it is possible to predict the measurement expected from the optical sensor when the temperature is increased from low to high temperature. The comparison between the predicted and experimental outputs informs on how the sensor is accurate. The second types are tests on a tensile test bench operating at high temperature. The Fabry-Perot measurements are compared, in the elastic domain, with the expected strain given by the Young modulus of the material, and also on a larger strain domain, with the measurements of a high temperature axial extensometer. Both types of tests are presented and commented.
In 1974 the composer Harrison Birtwistle commented to the author: 'On film you can show someone at the bottom of the stairs and then at the top.' This article explores the relevance of this statement to the compositional practices of Philip Grange. The focus is on Grange's Cloud Atlas (2009) for symphonic wind band, and how an adaption of the structure of David Mitchell's eponymous novel of 2004 is combined with a large-scale realisation of Birtwistle's statement to create a work employing structural eclipsing and narrative substitution that enables the 26 minutes of Grange's composition to suggest a duration twice as long. It forms the basis of a discussion involving Hertz's intertexturality to address the possible motivation for employing sources from other domains, while Jakobson's intersemiotic transmutation aids understanding of the processes involved. Finally, the desire to reveal non-musical sources is discussed using Eco's concept of 'resonances and echoes'.
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