75 research outputs found
Mapping Vesta: First Results from Dawn’s Survey Orbit
The geologic objectives of the Dawn Mission [1] are
to derive Vesta’s shape, map the surface geology,
understand the geological context and contribute to
the determination of the asteroids’ origin and
evolution.Geomorphology and distribution of surface features
will provide evidence for impact cratering, tectonic activity, volcanism, and regolith processes. Spectral
measurements of the surface will provide evidence of
the compositional characteristics of geological units.
Age information, as derived from crater sizefrequency
distributions, provides the stratigraphic
context for the structural and compositional mapping
results, thus revealing the geologic history of Vesta.
We present here the first results of the Dawn mission
from data collected during the approach to Vesta, and
its first discrete orbit phase – the Survey Orbit, which
lasts 21 days after the spacecraft had established a
circular polar orbit at a radius of ~3000 km with a
beta angle of 10°-15°
VVUQ of a thermal-hydraulic multi-scale tool on unprotected loss of flow accident in SFR reactor
Within the framework of the French 4th-generation Sodium-cooled Fast Reactor safety assessment, methodology on VVUQ (Verification, Validation, Uncertainty Quantification) is conducted to demonstrate that the CEA's thermal-hydraulic Scientific Computation Tools (SCTs) are effective and operational for design and safety studies purposes on this type of reactor. This VVUQ-based qualification is a regulatory requirement from the French Nuclear Safety Authority (NSA). In this paper, the current practice of VVUQ approach application for a SFR accidental transient is described with regard to the NSA requirements. It constitutes the first practical, progressively improvable approach. As the SCT is qualified for a given version on a given scenario, the transient related to a total unprotected station blackout has been selected. As it is a very complex multi-scale transient, the SCT MATHYS (which is a coupling of the CATHARE2 tool at system scale, TrioMC tool at component scale and TrioCFD tool at local scale) is used. This paper presents the preliminary VVUQ application to the qualification of this tool on this selected transient. In addition, this work underlines some feedback on design and R&D aspects that should be addressed in the future to improve the SCT
Initiation of the Primate Genome Project
This work was supported by the National Natural Science Foundation of China (31822048) and Strategic Priority Research Program of the Chinese Academy of Sciences (XDPB17
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