105,387 research outputs found
XB-70 flight test data comparisons with simulation predictions of inlet unstart and buzz
XB-70 flight test data comparison with simulated predictions of inlet unstart and buz
On optimal truncation of divergent series solutions of nonlinear differential systems; Berry smoothing
We prove that for divergent series solutions of nonlinear (or linear)
differential systems near a generic irregular singularity, the common
prescription of summation to the least term is, if properly interpreted,
meaningful and correct, and we extend this method to transseries solutions. In
every direction in the complex plane at the singularity (Stokes directions {\em
not} excepted) there exists a nonempty set of solutions whose difference from
the ``optimally'' (i.e., near the least term) truncated asymptotic series is of
the same (exponentially small) order of magnitude as the least term of the
series. There is a family of generalized Borel summation formulas
which commute with the usual algebraic and analytic operations (addition,
multiplication, differentiation, etc). We show that there is exactly one of
them, , such that for any formal series solution ,
differs from the optimal truncation of
by at most the order of the least term of . We show in addition that
the Berry (1989) smoothing phenomenon is universal within this class of
differential systems. Whenever the terms ``beyond all orders'' {\em change} in
crossing a Stokes line, these terms vary smoothly on the Berry scale
and the transition is always given by the error
function; under the same conditions we show that Dingle's rule of signs for
Stokes transitions holds
Structural ambiguity of the Chinese version of the hospital anxiety and depression scale in patients with coronary heart disease
Background
The Hospital Anxiety and Depression Scale (HADS) is a widely used screening tool designed as a case detector for clinically relevant anxiety and depression. Recent studies of the HADS in coronary heart disease (CHD) patients in European countries suggest it comprises three, rather than two, underlying sub-scale dimensions. The factor structure of the Chinese version of the HADS was evaluated in patients with CHD in mainland China.
Methods
Confirmatory factor analysis (CFA) was conducted on self-report HADS forms from 154 Chinese CHD patients.
Results
Little difference was observed in model fit between best performing three-factor and two-factor models.
Conclusion
The current observations are inconsistent with recent studies highlighting a dominant underlying tri-dimensional structure to the HADS in CHD patients. The Chinese version of the HADS may perform differently to European language versions of the instrument in patients with CHD
Phase-locked loop with sideband rejecting properties Patent
Phase locked loop with sideband rejecting properties in continuous wave tracking rada
Capillary Waves at Liquid/Vapor Interfaces: A Molecular Dynamics Simulation
Evidence for capillary waves at a liquid/vapor interface are presented from
extensive molecular dynamics simulations of a system containing up to 1.24
million Lennard-Jones particles. Careful measurements show that the total
interfacial width depends logarithmically on , the length of the
simulation cell parallel to the interface, as predicted theoretically. The
strength of the divergence of the interfacial width on depends
inversely on the surface tension . This allows us to measure
two ways since can also be obtained from the difference in the
pressure parallel and perpendicular to the interface. These two independent
measures of agree provided that the interfacial order parameter
profile is fit to an error function and not a hyperbolic tangent, as often
assumed. We explore why these two common fitting functions give different
results for
Welding of commercial base plates is investigated
Investigation of aluminum alloy welds reveals that the combinations of metallic elements with hydrogen are not capable of producing weld porosity themselves, rather they tend to increase the amount of porosity only in the presence of arc contamination by water vapor
The fate of cannibalized fundamental-plane ellipticals
Evolution and disruption of galaxies orbiting in the gravitational field of a
larger cluster galaxy are driven by three coupled mechanisms: 1) the heating
due to its time dependent motion in the primary; 2) mass loss due to the tidal
strain field; and 3) orbital decay. Previous work demonstrated that tidal
heating is effective well inside the impulse approximation limit. Not only does
the overall energy increase over previous predictions, but the work is done
deep inside the secondary galaxy, e.g. at or inside the half mass radius in
most cases. Here, these ideas applied to cannibalization of elliptical galaxies
with fundamental-plane parameters. In summary, satellites which can fall to the
center of a cluster giant by dynamical friction are evaporated by internal
heating by the time they reach the center. This suggests that true
merger-produced multiple nuclei giants should be rare. Specifically,
secondaries with mass ratios as small as 1\% on any initial orbit evaporate and
those on eccentric orbits with mass ratios as small as 0.1\% evolve
significantly and nearly evaporate in a galaxian age. Captured satellites with
mass ratios smaller than roughly 1\% have insufficient time to decay to the
center. After many accretion events, the model predicts that the merged system
has a profile similar to that of the original primary with a weak increase in
concentration.Comment: 19 pages, 10 Postscript figures, uses aaspp4.sty. Submitted to
Astrophysical Journa
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