30,605 research outputs found
Computer program for determination of natural frequencies of closed spherical sandwich shells
Solutions for the axially symmetric motion of an elastic spherical sandwich shell have been obtained from a theory of shells which includes the effects of transverse shear deformation and rotary inertia. Frequency equations and mode shapes are derived for the full vibrations of a closed spherical shell
Maser radiometer for cosmic background radiation anisotropy measurements
A maser amplifier was incorporated into a low noise radiometer designed to measure large-scale anisotropy in the 3 deg K microwave background radiation. To minimize emission by atmospheric water vapor and oxygen, the radiometer is flown in a small balloon to an altitude to 25 km. Three successful flights were made - two from Palestine, Texas and one from Sao Jose dos Campos, Brazil. Good sky coverage is important to the experiment. Data from the northern hemisphere flights has been edited and calibrated
Study of Apollo water impact. Volume 6 - User's manual - Interaction Final report
Computer program for hydroelastic responses of flexible shells of revolution during axially symmetric impact into incompressible fluids as in Apollo water impac
Absorption of Energy at a Metallic Surface due to a Normal Electric Field
The effect of an oscillating electric field normal to a metallic surface may
be described by an effective potential. This induced potential is calculated
using semiclassical variants of the random phase approximation (RPA). Results
are obtained for both ballistic and diffusive electron motion, and for two and
three dimensional systems. The potential induced within the surface causes
absorption of energy. The results are applied to the absorption of radiation by
small metal spheres and discs. They improve upon an earlier treatment which
used the Thomas-Fermi approximation for the effective potential.Comment: 19 pages (Plain TeX), 2 figures, 1 table (Postscript
Non-equilibrium steady state of sparse systems
A resistor-network picture of transitions is appropriate for the study of
energy absorption by weakly chaotic or weakly interacting driven systems. Such
"sparse" systems reach a novel non-equilibrium steady state (NESS) once coupled
to a bath. In the stochastic case there is an analogy to the physics of
percolating glassy systems, and an extension of the fluctuation-dissipation
phenomenology is proposed. In the mesoscopic case the quantum NESS might differ
enormously from the stochastic NESS, with saturation temperature determined by
the sparsity. A toy model where the sparsity of the system is modeled using a
log-normal random ensemble is analyzed.Comment: 6 pages, 6 figures, EPL accepted versio
Study of Apollo water impact. Volume 2 - Dynamic response of shells of revolution during vertical impact into water - No interaction Final report
Mathematical model for predicting dynamic response of thin elastic shells of revolution during water impac
Research in primary care complementary and alternative medicine provision: an integral part of NHS clinical governance activity
The 1997 UK government white paper "The New NHS: Modern, Dependable", introduced a legal requirement for the NHS to provide accountable and quality assured services. Clinical governance was described by Scally and Donaldson (1998) as the "...system through which NHS organisations are accountable for continuously improving the quality of their
services and safeguarding high standards of care by creating an environment in which excellence in clinical care will flourish." An organisational culture that "...creates a working environment which is open and participative, where ideas and good practice are shared, where education and research are valued...is likely to be one where clinical governance thrives.
Amplification of High Harmonics Using Weak Perturbative High Frequency Radiation
The mechanism underlying the substantial amplification of the high-order
harmonics q \pm 2K (K integer) upon the addition of a weak seed XUV field of
harmonic frequency q\omega to a strong IR field of frequency \omega is analyzed
in the framework of the quantum-mechanical Floquet formalism and the
semiclassical re-collision model. According to the Floquet analysis, the
high-frequency field induces transitions between several Floquet states and
leads to the appearance of new dipole cross terms. The semiclassical
re-collision model suggests that the origin of the enhancement lies in the
time-dependent modulation of the ground electronic state induced by the XUV
field.Comment: 8 pages, 2 figure
Total Quantum Zeno effect and Intelligent States for a two level system in a squeezed bath
In this work we show that by frequent measurements of adequately chosen
observables, a complete suppression of the decay in an exponentially decaying
two level system interacting with a squeezed bath is obtained. The observables
for which the effect is observed depend on the the squeezing parameters of the
bath. The initial states which display Total Zeno Effect are intelligent states
of two conjugate observables associated to the electromagnetic fluctuations of
the bath.Comment: 5 pages, 3 figure
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