73 research outputs found
Quasilinearization Method and Summation of the WKB Series
Solutions obtained by the quasilinearization method (QLM) are compared with
the WKB solutions. Expansion of the -th QLM iterate in powers of
reproduces the structure of the WKB series generating an infinite number of the
WKB terms with the first terms reproduced exactly. The QLM quantization
condition leads to exact energies for the P\"{o}schl-Teller, Hulthen,
Hylleraas, Morse, Eckart potentials etc. For other, more complicated potentials
the first QLM iterate, given by the closed analytic expression, is extremely
accurate. The iterates converge very fast. The sixth iterate of the energy for
the anharmonic oscillator and for the two-body Coulomb Dirac equation has an
accuracy of 20 significant figures
Effects of Nacelle configuration/position on performance of subsonic transport
An experimental study was conducted to explore possible reductions in installed propulsion system drag due to underwing aft nacelle locations. Both circular (C) and D inlet cross section nacelles were tested. The primary objectives were: to determine the relative installed drag of the C and D nacelle installations; and, to compare the drag of each aft nacelle installation with that of a conventional underwing forward, drag of each aft nacelle installation with that of a conventional underwing forward, pylon mounted (UTW) nacelle installation. The tests were performed in the NASA-Langley Research Center 16-Foot Transonic Wind Tunnel at Mach numbers from 0.70 to 0.85, airplane angles of attack from -2.5 to 4.1 degrees, and Reynolds numbers per foot from 3.4 to 4.0 million. The nacelles were installed on the NASA USB full span transonic transport model with horizontal tail on. The D nacelle installation had the smallest drag of those tested. The UTW nacelle installation had the largest drag, at 6.8 percent larger than the D at Mach number 0.80 and lift coefficient (C sub L) 0.45. Each tested configuration still had some interference drag, however. The effect of the aft nacelles on airplane lift was to increase C sub L at a fixed angle of attack relative to the wing body. There was higher lift on the inboard wing sections because of higher pressures on the wing lower surface. The effects of the UTW installation on lift were opposite to those of the aft nacelles
Spin dependent operators in correlated gaussian bases
In their textbook, Suzuki and Varga [Y. Suzuki and K. Varga, {\em Stochastic
Variational Approach to Quantum-Mechanical Few-Body Problems} (Springer,
Berlin, 1998)] present the stochastic variational method with the correlated
Gaussian basis in a very exhaustive way. The matrix elements for central
potentials are put under a pleasant form but the elements for spin dependent
operators, when treated, are given as very cumbersome expressions. In this
paper, we find a lot of new formulae for those elements. Their expressions are
given in terms of the same geometrical functions that appear in the case of
central potentials. These functions get therefore a universal status; this
property is very useful for numerical applications.Comment: 16 page
Independent Eigenstates of Angular Momentum in a Quantum N-body System
The global rotational degrees of freedom in the Schr\"{o}dinger equation for
an -body system are completely separated from the internal ones. After
removing the motion of center of mass, we find a complete set of
independent base functions with the angular momentum . These are
homogeneous polynomials in the components of the coordinate vectors and the
solutions of the Laplace equation, where the Euler angles do not appear
explicitly. Any function with given angular momentum and given parity in the
system can be expanded with respect to the base functions, where the
coefficients are the functions of the internal variables. With the right choice
of the base functions and the internal variables, we explicitly establish the
equations for those functions. Only (3N-6) internal variables are involved both
in the functions and in the equations. The permutation symmetry of the wave
functions for identical particles is discussed.Comment: 24 pages, no figure, one Table, RevTex, Will be published in Phys.
Rev. A 64, 0421xx (Oct. 2001
Photoionization accompanied by excitation at intermediate photon energies
We calculate the photoionization with excitation-to photoionization ratios
for atomic helium and heliumlike ions at intermediate values of the photon
energies. The final state interactions between the electrons are included in
the lowest order of their Sommerfeld parameter. This enables us, in contrast to
purely numerical calculations to investigate the roles of various mechanisms
contributing beyond the high energy limit. The system of the two bound
electrons is described by the functions obtained by the Correlation Function
Hyperspherical Harmonic Method. For the case of heliumlike ions we present the
high energy limits as power expansion in inverse charge of the nucleus. We
analyse the role of excitation of states with the nonzero orbital momenta.Comment: 3 figure
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