45 research outputs found
Future Challenges and Unsolved Problems in Multi-field Visualization
Evaluation, solved and unsolved problems, and future directions are popular themes pervading the visualization community over the last decade. The top unsolved problem in both scientific and information visualization was the subject of an IEEE Visualization Conference panel in 2004. The future of graphics hardware was another important topic of discussion the same year. The subject of how to evaluate visualization returned a few years later. Chris Johnson published a list of 10 top problems in scientific visualization research. This was followed up by report of both past achievements and future challenges in visualization research as well as financial support recommendations to the National Science Foundation (NSF) and National Institute of Health (NIH). Chen recently published the first list of top unsolved information visualization problems. Future research directions of topology-based visualization was also a major theme of a workshop on topology-based methods. Laramee and Kosara published a list of top future challenges in human-centered visualization
Skeletons for Distributed Topological Computation
Parallel implementation of topological algorithms is highly desirable, but the challenges, from reconstructing algorithms around independent threads through to runtime load balancing, have proven to be formidable. This problem, made all the more acute by the diversity of hardware platforms, has led to new kinds of implementation platform for computational science, with sophisticated runtime systems managing and coordinating large threadcounts to keep processing elements heavily utilized. While simpler and more portable than direct management of threads, these approaches still entangle program logic with resource management. Similar kinds of highly parallel runtime system have also been developed for functional languages. Here, however, language support for higher-order functions allows a cleaner separation between the algorithm and `skeletons' that express generic patterns of parallel computation. We report results on using this technique to develop a distributed version of the Joint Contour Net, a generalization of the Contour Tree to multifields. We present performance comparisons against a recent Haskell implementation using shared-memory parallelism, and initial work on a skeleton for distributed memory implementation that utilizes an innovative strategy to reduce inter-process communication overheads
Multi-fidelity Emulator for Cosmological Large Scale 21 cm Lightcone Images: a Few-shot Transfer Learning Approach with GAN
Large-scale numerical simulations () of cosmic
reionization are required to match the large survey volume of the upcoming
Square Kilometre Array (SKA). We present a multi-fidelity emulation technique
for generating large-scale lightcone images of cosmic reionization. We first
train generative adversarial networks (GAN) on small-scale simulations and
transfer that knowledge to large-scale simulations with hundreds of training
images. Our method achieves high accuracy in generating lightcone images, as
measured by various statistics with mostly percentage errors. This approach
saves computational resources by 90% compared to conventional training methods.
Our technique enables efficient and accurate emulation of large-scale images of
the Universe.Comment: Accepted at the ICML 2023 Workshop on Machine Learning for
Astrophysic
N=1,2 Super-NLS Hierarchies as Super-KP Coset Reductions
We define consistent finite-superfields reductions of the super-KP
hierarchies via the coset approach we already developped for reducing the
bosonic KP-hierarchy (generating e.g. the NLS hierarchy from the
coset). We work in a manifestly supersymmetric framework
and illustrate our method by treating explicitly the super-NLS
hierarchies. W.r.t. the bosonic case the ordinary covariant derivative is now
replaced by a spinorial one containing a spin
superfield. Each coset reduction is associated to a rational super-\cw
algebra encoding a non-linear super-\cw_\infty algebra structure. In the
case two conjugate sets of superLax operators, equations of motion and
infinite hamiltonians in involution are derived. Modified hierarchies are
obtained from the original ones via free-fields mappings (just as a m-NLS
equation arises by representing the algebra through the
classical Wakimoto free-fields).Comment: 27 pages, LaTex, Preprint ENSLAPP-L-467/9
Inflation in a two 3-form fields scenario
A setting constituted by 3-form fields, without any direct
interaction between them, minimally coupled to gravity, is introduced in this
paper as a framework to study the early evolution of the universe. We focus
particularly on the two 3-forms case. An inflationary scenario is found,
emerging from the coupling to gravity. More concretely, the fields coupled in
this manner exhibit a complex interaction, mediated by the time derivative of
the Hubble parameter. Our investigation is supported by means of a suitable
choice of potentials, employing numerical methods and analytical
approximations. In more detail, the oscillations on the small field limit
become correlated, and one field is intertwined with the other. In this type of
solution, a varying sound speed is present, together with the generation of
isocurvature perturbations. The mentioned features allow to consider an
interesting model, to test against observation. It is subsequently shown how
our results are consistent with current CMB data (viz.Planck and BICEP2).Comment: Version accepted in JCAP. 22 pages, 12 figures, new refs adde