16,285 research outputs found
Numerical methods for the design and analysis of wings at supersonic speeds
Numerical methods for the design and analysis of arbitrary-planform wings at supersonic speeds are reviewed. Certain deficiencies are revealed, particularly in application to wings with slightly subsonic leading edges. Recently devised numerical techniques which overcome the major part of these deficiencies are presented. The original development as well as the more recent revisions are subjected to a thorough review
A linearized theory method of constrained optimization for supersonic cruise wing design
A linearized theory wing design and optimization procedure which allows physical realism and practical considerations to be imposed as constraints on the optimum (least drag due to lift) solution is discussed and examples of application are presented. In addition to the usual constraints on lift and pitching moment, constraints are imposed on wing surface ordinates and wing upper surface pressure levels and gradients. The design procedure also provides the capability of including directly in the optimization process the effects of other aircraft components such as a fuselage, canards, and nacelles
Inclusive neutrino scattering off deuteron from threshold to GeV energies
Background: Neutrino-nucleus quasi-elastic scattering is crucial to interpret
the neutrino oscillation results in long baseline neutrino experiments. There
are rather large uncertainties in the cross section, due to insufficient
knowledge on the role of two-body weak currents. Purpose: Determine the role of
two-body weak currents in neutrino-deuteron quasi-elastic scattering up to GeV
energies. Methods: Calculate cross sections for inclusive neutrino scattering
off deuteron induced by neutral and charge-changing weak currents, from
threshold up to GeV energies, using the Argonne potential and
consistent nuclear electroweak currents with one- and two-body terms. Results:
Two-body contributions are found to be small, and increase the cross sections
obtained with one-body currents by less than 10% over the whole range of
energies. Total cross sections obtained by describing the final two-nucleon
states with plane waves differ negligibly, for neutrino energies
MeV, from those in which interaction effects in these states are fully
accounted for. The sensitivity of the calculated cross sections to different
models for the two-nucleon potential and/or two-body terms in the weak current
is found to be weak. Comparing cross sections to those obtained in a naive
model in which the deuteron is taken to consist of a free proton and neutron at
rest, nuclear structure effects are illustrated to be non-negligible.
Conclusion: Contributions of two-body currents in neutrino-deuteron
quasi-elastic scattering up to GeV are found to be smaller than 10%. Finally,
it should be stressed that the results reported in this work do not include
pion production channels.Comment: 30 pages, 17 figures; publishe
The equation of state of neutron matter, symmetry energy, and neutron star structure
We review the calculation of the equation of state of pure neutron matter
using quantum Monte Carlo (QMC) methods. QMC algorithms permit the study of
many-body nuclear systems using realistic two- and three-body forces in a
nonperturbative framework. We present the results for the equation of state of
neutron matter, and focus on the role of three-neutron forces at supranuclear
density. We discuss the correlation between the symmetry energy, the neutron
star radius and the symmetry energy. We also combine QMC and theoretical models
of the three-nucleon interactions, and recent neutron star observations to
constrain the value of the symmetry energy and its density dependence.Comment: 11 pages, 11 figure
Inter-relations between advanced processing techniques, integrated circuits, materials development and analysis Quarterly report, 1 Mar. - 31 May 1969
Gyrator tuned circuit amplifier and microcircuit interconnection
Hysteresis and Noise from Electronic Nematicity in High Temperature Superconductors
An electron nematic is a translationally invariant state which spontaneously
breaks the discrete rotational symmetry of a host crystal. In a clean square
lattice, the electron nematic has two preferred orientations, while dopant
disorder favors one or the other orientations locally. In this way, the
electron nematic in a host crystal maps to the random field Ising model (RFIM).
Since the electron nematic has anisotropic conductivity, we associate each
Ising configuration with a resistor network, and use what is known about the
RFIM to predict new ways to test for electron nematicity using noise and
hysteresis. In particular, we have uncovered a remarkably robust linear
relation between the orientational order and the resistance anisotropy which
holds over a wide range of circumstances.Comment: References added; minor wording change
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