21,505 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
Baryon Resonance Analysis from MAID
The unitary isobar model MAID2007 has been used to analyze the recent data of
pion electroproduction. The model contains all four-star resonances in the
region below W=2 GeV and both single-Q^2 and Q^2 dependent transition form
factors could be obtained for the Delta, Roper, D13(1520), S11(1535),
S31(1620), S11(1650), D15(1675), F15(1680) and P13(1720). From the complete
world data base, including also pi- data on the neutron, also Q^2 dependent
neutron form factors are obtained. For all transition form factors we also give
convenient numerical parameterizations that can be used in other reactions.
Furthermore, we show how the transition form factors can be used to obtain
empirical transverse charge densities and our first results are given for the
Roper, the S11 and D13 resonances.Comment: 8 pages, 11 figures, 4 tables, Proc. of NSTAR2009, Beijin
Spin Response and Neutrino Emissivity of Dense Neutron Matter
We study the spin response of cold dense neutron matter in the limit of zero
momentum transfer, and show that the frequency dependence of the
long-wavelength spin response is well constrained by sum-rules and the
asymptotic behavior of the two-particle response at high frequency. The
sum-rules are calculated using Auxiliary Field Diffusion Monte Carlo technique
and the high frequency two-particle response is calculated for several
nucleon-nucleon potentials. At nuclear saturation density, the sum-rules
suggest that the strength of the spin response peaks at 40--60
MeV, decays rapidly for 100 MeV, and has a sizable strength below
40 MeV. This strength at relatively low energy may lead to enhanced neutrino
production rates in dense neutron-rich matter at temperatures of relevance to
core-collapse supernova.Comment: 11 pages, 4 figures. Minor change. Published versio
- …