12,978 research outputs found
The Maryland soft shell clam industry and its effects on Tidewater resources
This report to the Maryland General Assembly covers: design and operation of the hydraulic clam dredge; summary of knowledge of Maryland's soft shell clam resource; development and present status; Potential value of the resource; Effects of the hydraulic clam dredge; evaluation of the effects of certain proposals concerning the soft shell clam industry; summary
Analytical procedure for determining random load acting on a spacecraft due to a primary random load acting on an exterior structure Quarterly report no. 2, 1 Sep. - 30 Nov. 1965
Sound and vibration transmission in OGO SPACECRAFT shroud syste
Inter- and Intra-Chain Attractions in Solutions of Flexible Polyelectrolytes at Nonzero Concentration
Constant temperature molecular dynamics simulations were used to study
solutions of flexible polyelectrolyte chains at nonzero concentrations with
explicit counterions and unscreened coulombic interactions. Counterion
condensation, measured via the self-diffusion coefficient of the counterions,
is found to increase with polymer concentration, but contrary to the prediction
of Manning theory, the renormalized charge fraction on the chains decreases
with increasing Bjerrum length without showing any saturation. Scaling analysis
of the radius of gyration shows that the chains are extended at low polymer
concentrations and small Bjerrum lengths, while at sufficiently large Bjerrum
lengths, the chains shrink to produce compact structures with exponents smaller
than a gaussian chain, suggesting the presence of attractive intrachain
interactions. A careful study of the radial distribution function of the
center-of-mass of the polyelectrolyte chains shows clear evidence that
effective interchain attractive interactions also exist in solutions of
flexible polyelectrolytes, similar to what has been found for rodlike
polyelectrolytes. Our results suggest that the broad maximum observed in
scattering experiments is due to clustering of chains.Comment: 12 pages, REVTeX, 15 eps figure
Transonic pressure measurements and comparison of theory to experiment for an arrow-wing configuration. Volume 1: Experimental data report, base configuration and effects of wing twist and leading-edge configuration
A wind tunnel test of an arrow-wing-body configuration consisting of flat and twisted wings, as well as a variety of leading- and trailing-edge control surface deflections, was conducted at Mach numbers from 0.4 to 1.1 to provide an experimental pressure data base for comparison with theoretical methods. Theory-to-experiment comparisons of detailed pressure distributions were made using current state-of-the-art attached and separated flow methods. The purpose of these comparisons was to delineate conditions under which these theories are valid for both flat and twisted wings and to explore the use of empirical methods to correct the theoretical methods where theory is deficient
Transonic pressure measurements and comparison of theory to experiment for an arrow-wing configuration. Volume 2: Experimental data report, effects of control surface deflection
For abstract, see N76-11034
Niche Markets
Is evolutionary theory is incomplete and are we failing to understand phenomena as disparate as ecosystem development and the interplay of genes and culture in shaping human evolution
Aeroacoustic research facilities at NASA Langley Research Center: Description and operational characteristics
A number of facilities were developed which provide unique test capabilities for aeroacoustic research. Information regarding physical layouts, dimensions, construction features, and operating capabilities of these facilities is compiled. Possible research applications include the behavior of such noise sources as jets, rotors, and propellers in simulated forward motion; studies of noise due to the interactions of aerodynamic flows with solid surfaces and bodies; sound propagation in ducts with airflow; and the evaluation of acoustical materials
Photon collection from a trapped ion--cavity system
We present the design and implementation of a trapped ion cavity QED system.
A single ytterbium ion is confined by a micron-scale ion trap inside a 2 mm
optical cavity. The ion is coherently pumped by near resonant laser light while
the cavity output is monitored as a function of pump intensity and cavity
detuning. We observe a Purcell enhancement of scattered light into the solid
angle subtended by the optical cavity, as well as a three-peak structure
arising from strongly driving the atom. This system can be integrated into
existing atom{photon quantum network protocols and is a pathway towards an
efficient atom{photon quantum interface
Scaling and Universality in the Counterion-Condensation Transition at Charged Cylinders
We address the critical and universal aspects of counterion-condensation
transition at a single charged cylinder in both two and three spatial
dimensions using numerical and analytical methods. By introducing a novel
Monte-Carlo sampling method in logarithmic radial scale, we are able to
numerically simulate the critical limit of infinite system size (corresponding
to infinite-dilution limit) within tractable equilibration times. The critical
exponents are determined for the inverse moments of the counterionic density
profile (which play the role of the order parameters and represent the inverse
localization length of counterions) both within mean-field theory and within
Monte-Carlo simulations. In three dimensions (3D), correlation effects
(neglected within mean-field theory) lead to an excessive accumulation of
counterions near the charged cylinder below the critical temperature
(condensation phase), while surprisingly, the critical region exhibits
universal critical exponents in accord with the mean-field theory. In two
dimensions (2D), we demonstrate, using both numerical and analytical
approaches, that the mean-field theory becomes exact at all temperatures
(Manning parameters), when number of counterions tends to infinity. For finite
particle number, however, the 2D problem displays a series of peculiar singular
points (with diverging heat capacity), which reflect successive de-localization
events of individual counterions from the central cylinder. In both 2D and 3D,
the heat capacity shows a universal jump at the critical point, and the energy
develops a pronounced peak. The asymptotic behavior of the energy peak location
is used to locate the critical temperature, which is also found to be universal
and in accordance with the mean-field prediction.Comment: 31 pages, 16 figure
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