41,916 research outputs found
Thermal control for storage of cryogenic propellants in a common-bulkhead tank: A concept
Simple, reliable ground-hold refrigeration system for common-bulkhead tank meets design criteria and objectives for ground-hold of oxygen difluoride and diborane. System is failsafe and malfunctions can be rectified without interruption of basic system functions
Safe transport of diborane in a dual refrigerant system: A concept
Mobile transport system, that can be carried by truck and parked in storage area, consists of an inner container capable of holding 363 kg of diborane and an external, dual refrigeration unit which uses liquid nitrogen and Freon-14
The Skyrme Interaction in finite nuclei and nuclear matter
Self-consistent mean-field models are a powerful tool in the investigation of
nuclear structure and low-energy dynamics. They are based on effective
energy-density functionals, often formulated in terms of effective
density-dependent nucleon-nucleon interactions. The free parameters of the
functional are adjusted to empirical data. A proper choice of these parameters
requires a comprehensive set of constraints covering experimental data on
finite nuclei, concerning static as well as dynamical properties, empirical
characteristics of nuclear matter, and observational information on
nucleosynthesis, neutron stars and supernovae. This work aims at a
comprehensive survey of the performance of one of the most successful
non-relativistic self-consistent method, the Skyrme-Hartree-Fock model (SHF),
with respect to these constraints. A full description of the Skyrme functional
is given and its relation to other effective interactions is discussed. The
validity of the application of SHF far from stability and in dense environments
beyond the nuclear saturation density is critically assessed. The use of SHF in
models extended beyond the mean field approximation by including some
correlations is discussed. Finally, future prospects for further development of
SHF towards a more consistent application of the existing and promisingly newly
developing constraints are outlined.Comment: 71 pages, 22 figures. Accepted for publication in Prog.Part.Nucl.Phy
Relaxation and breakup of an initially extended drop in an otherwise quiescent fluid
In this paper we examine some general features of the time-dependent dynamics of drop deformation and breakup at low Reynolds numbers. The first aspect of our study is a detailed numerical investigation of the ‘end-pinching’ behaviour reported in a previous experimental study. The numerics illustrate the effects of viscosity ratio and initial drop shape on the relaxation and/or breakup of highly elongated droplets in an otherwise quiescent fluid. In addition, the numerical procedure is used to study the simultaneous development of capillary-wave instabilities at the fluid-fluid interface of a very long, cylindrically shaped droplet with bulbous ends. Initially small disturbances evolve to finite amplitude and produce very regular drop breakup. The formation of satellite droplets, a nonlinear phenomenon, is also observed
Satellite observations of type 3 solar radio bursts at low frequencies
Type III solar radio bursts were observed from 10 MHz to 10 KHz by satellite experiments above the terrestrial plasmasphere. Solar radio emission in this frequency range results from excitation of the interplanetary plasma by energetic particles propagating outward along open field lines over distances from 5 solar radii to at least 1 AU from the sun. This review summarizes the morphology, characteristics and analysis of individual as well as storms of bursts. Burst rise times are interpreted in terms of exciter length and dispersion while decay times refer to the radiation damping process. The combination of radio observations at the lower frequencies and in-situ measurements on nonrelativistic electrons at 1 AU provide data on the energy range and efficiency of the wave-particle interactions responsible for the radio emission
From Microscales to Macroscales in 3D: Selfconsistent Equation of State for Supernova and Neutron Star Models
First results from a fully self-consistent, temperature-dependent equation of
state that spans the whole density range of neutron stars and supernova cores
are presented. The equation of state (EoS) is calculated using a mean-field
Hartree-Fock method in three dimensions (3D). The nuclear interaction is
represented by the phenomenological Skyrme model in this work, but the EoS can
be obtained in our framework for any suitable form of the nucleon-nucleon
effective interaction. The scheme we employ naturally allows effects such as
(i) neutron drip, which results in an external neutron gas, (ii) the variety of
exotic nuclear shapes expected for extremely neutron heavy nuclei, and (iii)
the subsequent dissolution of these nuclei into nuclear matter. In this way,
the equation of state is calculated across phase transitions without recourse
to interpolation techniques between density regimes described by different
physical models. EoS tables are calculated in the wide range of densities,
temperature and proton/neutron ratios on the ORNL NCCS XT3, using up to 2000
processors simultaneously.Comment: 6 pages, 11 figures. Published in conference proceedings Journal of
Physics: Conference Series 46 (2006) 408. Extended version to be submitted to
Phys. Rev.
Type 3 solar radio burst storms observed at low frequencies. Part 1 - Storm morphology
Low-frequency observations of type 3 solar radio bursts as function of solar rotatio
Up-Down Asymmetry of Neutral Current Events as a Diagnostic for Nu_mu - Nu-st Versus Nu_mu- Nu_tau Oscillations
We show that the asymmetry in the neutral current events (e.g. Nu N -> Nu N
pi^0) can be used to discriminate between Nu_mu - Nu_tau and Nu_mu - Nu_st
mixing as being responsible for the atmospheric neutrino anomaly. Specifically,
A_N vanishes for Nu_mu - Nu_tau mixing and is about 2/3 A_mu for Nu_mu - Nu_st
mixing.Comment: 3pages, 1 figur
- …