343 research outputs found
X-ray characterisation of bulk stones from the patina to the depth stone
The aim of this study on monumental limestone alteration is to characterise the superficial stone called patina where transformation processes due to air and water occur. We present results on stones from the Chambord castle, so Tuffeau limestone, from the Loire Valley. Three samples has been studied and compared in relationship with their position on the monument (outside or inside). In order to describe these samples, different techniques have been used : chemical analysis, optical microscopy. The three main phases are calcite (CaCO 3), quartz and opal (SiO 2), with various granulometry. X-ray diffraction has been performed on bulk samples. A special sample holder allows to analyse very thin zones, so to describe the mineralogical composition from the epidermis to the depth stone [1]. The stones are constituted of small crystallites which differ in dimension and orientation. This conducts to a semi-quantitative description. Protecting layer of the stone is associated to the rate of dissolution of calcite in patina zone
Oxidation Resistance of Thermal Barrier Coatings Based on Hollow Alumina Particles
International audienc
Quantum Computing of Classical Chaos: Smile of the Arnold-Schrodinger Cat
We show on the example of the Arnold cat map that classical chaotic systems
can be simulated with exponential efficiency on a quantum computer. Although
classical computer errors grow exponentially with time, the quantum algorithm
with moderate imperfections is able to simulate accurately the unstable chaotic
classical dynamics for long times. The algorithm can be easily implemented on
systems of a few qubits.Comment: revtex, 4 pages, 4 figure
High resolution spectroscopy of Pluto's atmosphere: detection of the 2.3 m CH bands and evidence for carbon monoxide
The goal is to determine the composition of Pluto's atmosphere and to
constrain the nature of surface-atmosphere interactions.
We perform high--resolution spectroscopic observations in the 2.33--2.36
m range, using CRIRES at the VLT.
We obtain (i) the first detection of gaseous methane in this spectral range,
through lines of the + and + bands (ii) strong
evidence (6- confidence) for gaseous CO in Pluto. For an isothermal
atmosphere at 90 K, the CH and CO column densities are 0.75 and 0.07 cm-am,
within factors of 2 and 3, respectively. Using a physically--based thermal
structure model of Pluto's atmosphere also satisfying constraints from stellar
occultations, we infer CH and CO mixing ratios q=
0.6% (consistent with results from the 1.66 m range) and
q = 0.5. The CO atmospheric abundance is
consistent with its surface abundance. As for Triton, it is probably controlled
by a thin, CO-rich, detailed balancing layer resulting from seasonal transport
and/or atmospheric escape.Comment: Astronomy and Astrophysics Letters, in pres
Quantum Computing of Poincare Recurrences and Periodic Orbits
Quantum algorithms are built enabling to find Poincar\'e recurrence times and
periodic orbits of classical dynamical systems. It is shown that exponential
gain compared to classical algorithms can be reached for a restricted class of
systems. Quadratic gain can be achieved for a larger set of dynamical systems.
The simplest cases can be implemented with small number of qubits.Comment: revtex, 5 pages, research at Quantware MIPS Center (see
http://www.quantware.ups-tlse.fr); minor changes and references adde
A new access control unit for GANIL and SPIRAL 2
International audienceFor the GANIL safety revaluation and the new project of accelerator SPIRAL 2, it was decided to replace theexisting access control system for radiological controlled areas. These areas are all cyclotron rooms and experimental areas. The existing system is centralized around VME cards. Updating is becoming very problematic. The new UGA (access control unit) will becomposed of a pair of PLC to ensure the safety of each room. It will be supplemented by a system UGB (radiological control unit) that will assure the radiological monitoring of the area concerned
Exponential Gain in Quantum Computing of Quantum Chaos and Localization
We present a quantum algorithm which simulates the quantum kicked rotator
model exponentially faster than classical algorithms. This shows that important
physical problems of quantum chaos, localization and Anderson transition can be
modelled efficiently on a quantum computer. We also show that a similar
algorithm simulates efficiently classical chaos in certain area-preserving
maps.Comment: final published versio
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