774 research outputs found
Crystal structure of 4,4-dimethyl-2-(trifluoromethyl)-4,5-dihydro-1H-imidazole, C6H9F3N2
C6H9F3N2, monoclinic, P21/n (no. 14), a = 10.6224(9) Å, b = 11.8639(9) Å, c = 13.3139(11) Å, β = 105.903(3)°, V = 1613.6(2) Å3, Z = 8, Rgt(F) = 0.0618, wRref(F2) = 0.1629, T = 102(2) K [1–3]
Toward Five-dimensional Core-collapse Supernova Simulations
The computational difficulty of six-dimensional neutrino radiation
hydrodynamics has spawned a variety of approximations, provoking a long history
of uncertainty in the core-collapse supernova explosion mechanism. Under the
auspices of the Terascale Supernova Initiative, we are honoring the physical
complexity of supernovae by meeting the computational challenge head-on,
undertaking the development of a new adaptive mesh refinement code for
self-gravitating, six-dimensional neutrino radiation magnetohydrodynamics. This
code--called {\em GenASiS,} for {\em Gen}eral {\em A}strophysical {\em
Si}mulation {\em S}ystem--is designed for modularity and extensibility of the
physics. Presently in use or under development are capabilities for Newtonian
self-gravity, Newtonian and special relativistic magnetohydrodynamics (with
`realistic' equation of state), and special relativistic energy- and
angle-dependent neutrino transport--including full treatment of the energy and
angle dependence of scattering and pair interactions.Comment: 5 pages. Proceedings of SciDAC 2005, Scientific Discovery through
Advanced Computing, San Francisco, CA, 26-30 June 200
A logical layer to interpret user interactions
Some computing user interfaces include a large number of user-selectable options which can make it difficult for a user to locate the right option. Another frequent user interface problem is inadvertent or unintended invocation of actions, e.g., by selection of an incorrect icon from two icons placed close to each other. In some user interfaces, simple actions sometimes require a disproportionately tedious sequence of interactions. This disclosure introduces a layer between the user and the application such that user commands or interactions are interpreted in light of past interactions, and corrected, filtered or automated as appropriate. Past interactions are utilized, and interpretation or corrective action is performed only upon permission from the user. For ease of interaction, such permission is obtained, e.g., at initial setup, and is modifiable
Advancing Nucleosynthesis in Self-consistent, Multidimensional Models of Core-Collapse Supernovae
We investigate core-collapse supernova (CCSN) nucleosynthesis in polar
axisymmetric simulations using the multidimensional radiation hydrodynamics
code CHIMERA. Computational costs have traditionally constrained the evolution
of the nuclear composition in CCSN models to, at best, a 14-species
-network. Such a simplified network limits the ability to accurately
evolve detailed composition, neutronization and the nuclear energy generation
rate. Lagrangian tracer particles are commonly used to extend the nuclear
network evolution by incorporating more realistic networks in post-processing
nucleosynthesis calculations. Limitations such as poor spatial resolution of
the tracer particles, estimation of the expansion timescales, and determination
of the "mass-cut" at the end of the simulation impose uncertainties inherent to
this approach. We present a detailed analysis of the impact of these
uncertainties on post-processing nucleosynthesis calculations and implications
for future models.Comment: Proceedings of the 13th Symposium on Nuclei in the Cosmos. 7-11 July
2014. Debrecen, Hungar
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