10 research outputs found
: A Reduced-Order Modeling Framework based on Machine Learning for Real-Time Applications
Digital twins have emerged as a key technology for optimizing the performance
of engineering products and systems. High-fidelity numerical simulations
constitute the backbone of engineering design, providing an accurate insight
into the performance of complex systems. However, large-scale, dynamic,
non-linear models require significant computational resources and are
prohibitive for real-time digital twin applications. To this end, reduced order
models (ROMs) are employed, to approximate the high-fidelity solutions while
accurately capturing the dominant aspects of the physical behavior. The present
work proposes a new machine learning (ML) platform for the development of ROMs,
to handle large-scale numerical problems dealing with transient nonlinear
partial differential equations. Our framework, mentioned as
, utilizes a singular value
decomposition (SVD) update methodology, to compute a linear subspace of the
multi-fidelity solutions during the simulation process,
convolutional autoencoders for nonlinear dimensionality reduction,
feed-forward neural networks to map the input parameters to
the latent spaces, and long short-term memory networks to
predict and forecast the dynamics of parametric solutions. The efficiency of
the framework is demonstrated for a 2D linear
convection-diffusion equation, the problem of fluid around a cylinder, and the
3D blood flow inside an arterial segment. The accuracy of the reconstructed
results demonstrates the robustness and assesses the efficiency of the proposed
approach.Comment: 35 pages, 22 figure
KelvinâHelmholtz instabilities at the magnetic cavity boundary of comet 67P/ChuryumovâGerasimenko
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94670/1/jgra21763.pd
Triple F - a comet nucleus sample return mission
The Triple F (Fresh From the Fridge) mission, a Comet Nucleus Sample Return, has been proposed to ESA's Cosmic Vision program. A sample return from a comet enables us to reach the ultimate goal of cometary research. Since comets are the least processed bodies in the solar system, the proposal goes far beyond cometary science topics (like the explanation of cometary activity) and delivers invaluable information about the formation of the solar system and the interstellar molecular cloud from which it formed. The proposed mission would extract three sample cores of the upper 50cm from three locations on a cometary nucleus and return them cooled to Earth for analysis in the laboratory. The simple mission concept with a touch-and-go sampling by a single spacecraft was proposed as an M-class mission in collaboration with the Russian space agency ROSCOSMOS. Ă© The Author(s) 2008
On the origin and evolution of the material in 67P/Churyumov-Gerasimenko
International audiencePrimitive objects like comets hold important information on the material that formed our solar system. Several comets have been visited by spacecraft and many more have been observed through Earth- and space-based telescopes. Still our understanding remains limited. Molecular abundances in comets have been shown to be similar to interstellar ices and thus indicate that common processes and conditions were involved in their formation. The samples returned by the Stardust mission to comet Wild 2 showed that the bulk refractory material was processed by high temperatures in the vicinity of the early sun. The recent Rosetta mission acquired a wealth of new data on the composition of comet 67P/Churyumov-Gerasimenko (hereafter 67P/C-G) and complemented earlier observations of other comets. The isotopic, elemental, and molecular abundances of the volatile, semi-volatile, and refractory phases brought many new insights into the origin and processing of the incorporated material. The emerging picture after Rosetta is that at least part of the volatile material was formed before the solar system and that cometary nuclei agglomerated over a wide range of heliocentric distances, different from where they are found today. Deviations from bulk solar system abundances indicate that the material was not fully homogenized at the location of comet formation, despite the radial mixing implied by the Stardust results. Post-formation evolution of the material might play an important role, which further complicates the picture. This paper discusses these major findings of the Rosetta mission with respect to the origin of the material and puts them in the context of what we know from other comets and solar system objects
The 16 T Dipole Development Program for FCC and HE-LHC
A future circular collider (FCC) with a center-of-mass energy of 100 TeV and a circumference of around 100 km, or an energy upgrade of the LHC (HE-LHC) to 27 TeV require bending magnets providing 16 T in a 50-mm aperture. Several development programs for these magnets, based on Nb3Sn technology, are being pursued in Europe and in the U.S. In these programs, cos-theta, block-type, common-coil, and canted-cos-theta magnets are explored; first model magnets are under manufacture; limits on conductor stress levels are studied; and a conductor with enhanced characteristics is developed. This paper summarizes and discusses the status, plans, and preliminary results of these programs
The 16 T Dipole Development Program for FCC and HE-LHC
A future circular collider (FCC) with a center-of-mass energy of 100 TeV and a circumference of around 100 km, or an energy upgrade of the LHC (HE-LHC) to 27 TeV require bending magnets providing 16 Tin a SO-mm aperture. Several development programs for these magnets, based on Nb3Sn technology, are being pursued in Europe and in the U.S. In these programs, cos-theta, block-type, common-coil, and canted-cos-theta magnets are explored; first model magnets are under manufacture; limits on conductor stress levels are studied; and a conductor with enhanced characteristics is developed. This paper summarizes and discusses the status, plans, and preliminary results of these programs