1,643 research outputs found
Dewpoint temperature inversions analyzed
Dewpoint temperature inversion, with regard to other simultaneous meteorological conditions, was examined to establish the influence of meteorological variables on the variation of dewpoint temperature with height. This report covers instrumentation and available data, all the climatological features of dewpoint inversions, and specific special cases
Low-momentum effective interaction in the three-dimensional approach
The formulation of the low-momentum effective interaction in the model space
Lee-Suzuki and the renormalization group methods is implemented in the
three-dimensional approach. In this approach the low-momentum effective
interaction V_{low k} has been formulated as a function of the magnitude of
momentum vectors and the angle between them. As an application the spin-isospin
independent Malfliet-Tjon potential has been used into the model space
Lee-Suzuki method and it has been shown that the low-momentum effective
interaction V_{low k} reproduces the same two-body observables obtained by the
bare potential V_{NN}.Comment: 15 pages, 5 eps figure
Isovector part of nuclear energy density functional from chiral two- and three-nucleon forces
A recent calculation of the nuclear energy density functional from chiral
two- and three-nucleon forces is extended to the isovector terms pertaining to
different proton and neutron densities. An improved density-matrix expansion is
adapted to the situation of small isospin-asymmetries and used to calculate in
the Hartree-Fock approximation the density-dependent strength functions
associated with the isovector terms. The two-body interaction comprises of
long-range multi-pion exchange contributions and a set of contact terms
contributing up to fourth power in momenta. In addition, the leading order
chiral three-nucleon interaction is employed with its parameters fixed in
computations of nuclear few-body systems. With this input one finds for the
asymmetry energy of nuclear matter the value MeV,
compatible with existing semi-empirical determinations. The strength functions
of the isovector surface and spin-orbit coupling terms come out much smaller
than those of the analogous isoscalar coupling terms and in the relevant
density range one finds agreement with phenomenological Skyrme forces. The
specific isospin- and density-dependences arising from the chiral two- and
three-nucleon interactions can be explored and tested in neutron-rich systems.Comment: 14 pages, 7 figures, to be published in European Physical Journal
Nuclear energy density functional from chiral two- and three-nucleon interactions
An improved density-matrix expansion is used to calculate the nuclear energy
density functional from chiral two- and three-nucleon interactions. The
two-body interaction comprises long-range one- and two-pion exchange
contributions and a set of contact terms contributing up to fourth power in
momenta. In addition we employ the leading order chiral three-nucleon
interaction with its parameters and fixed in
calculations of nuclear few-body systems. With this input the nuclear energy
density functional is derived to first order in the two- and three-nucleon
interaction. We find that the strength functions and
of the surface and spin-orbit terms compare in the relevant
density range reasonably with results of phenomenological Skyrme forces.
However, an improved description requires (at least) the treatment of the
two-body interaction to second order. This observation is in line with the
deficiencies in the nuclear matter equation of state that remain
in the Hartree-Fock approximation with low-momentum two- and three-nucleon
interactions.Comment: 16 pages, 12 figures, submitted to Eur. Phys. J.
Prediction Model for the Life of Nickel-cadmium Batteries in Geosynchronous Orbit Satellites
A mathematical model is described which predicts the service life of nickel-cadmium batteries designed for geosynchronous orbit satellites. Regression analysis technique is used to analyze orbital data on second generation trickle charged batteries. The model gives average cell voltage as a function of design parameters, operating parameters and time. The voltage model has the properties of providing a good fit to the data, good predictive capability, and agreement with known battery performance characteristics. Average cell voltage can be predicted to within 0.02 volts for up to 8 years. This modeling shows that these batteries will operate reliably for 10 years. Third-generation batteries are expected to operate even longer
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