7,887 research outputs found
Identification of volatile contaminants of space cabin materials Final report, Jan. 1967 - Feb. 1968
Screening tests on candidate construction materials for spacecraft cabins to determine gas-off and oxidation product
Effect of matrix parameters on mesoporous matrix based quantum computation
We present a solid state implementation of quantum computation, which
improves previously proposed optically driven schemes. Our proposal is based on
vertical arrays of quantum dots embedded in a mesoporous material which can be
fabricated with present technology. We study the feasibility of performing
quantum computation with different mesoporous matrices. We analyse which matrix
materials ensure that each individual stack of quantum dots can be considered
isolated from the rest of the ensemble-a key requirement of our scheme. This
requirement is satisfied for all matrix materials for feasible structure
parameters and GaN/AlN based quantum dots. We also show that one dimensional
ensembles substantially improve performances, even of CdSe/CdS based quantum
dots
The Onset of Nuclear Structure Effects in Near-Barrier Elastic Scattering of Weakly-Bound Nuclei: He and Li Compared
The elastic scattering of the halo nucleus He from heavy targets at
incident energies near the Coulomb barrier displays a marked deviation from the
standard Fresnel-type diffraction behavior. This deviation is due to the strong
Coulomb dipole breakup coupling produced by the Coulomb field of the heavy
target, a specific feature of the nuclear structure of He. We have
performed Continuum Discretized Coupled Channels calculations for the elastic
scattering of He and Li from Ni, Sn, Sm,
Ta and Pb targets in order to determine the range of
where this nuclear-structure specific coupling effect becomes
manifest. We find that the strong Coulomb dipole breakup coupling effect is
only clearly experimentally distinguishable for targets of .Comment: 10 pages with 3 figure
Experimental investigation of the SNAP-8 mercury Rankine-cycle power conversion system
Experimental investigation of SNAP 8 mercury Rankine cycle power conversion syste
PCS-1 testing, March - May 1970
Development, characteristics, and performance tests of turbine alternator assembly system and component part
Mesoporous matrices for quantum computation with improved response through redundance
We present a solid state implementation of quantum computation, which improves previously proposed optically driven schemes. Our proposal is based on vertical arrays of quantum dots embedded in a mesoporous material which can be fabricated with present technology. The redundant encoding typical of the chosen hardware protects the computation against gate errors and the effects of measurement induced noise. The system parameters required for quantum computation applications are calculated for II-VI and III-V materials and found to be within the experimental range. The proposed hardware may help minimize errors due to polydispersity of dot sizes, which is at present one of the main problems in relation to quantum dot-based quantum computation. (c) 2007 American Institute of Physics
Robust optical flow with combined Lucas-Kanade/Horn-Schunck and automatic neighborhood selection
Nucleon momentum distribution in deuteron and other nuclei within the light-front dynamics method
The relativistic light-front dynamics (LFD) method has been shown to give a
correct description of the most recent data for the deuteron monopole and
quadrupole charge form factors obtained at the Jefferson Laboratory for elastic
electron-deuteron scattering for six values of the squared momentum transfer
between 0.66 and 1.7 (GeV/c). The good agreement with the data is in
contrast with the results of the existing non-relativistic approaches. In this
work we firstly make a complementary test of the LFD applying it to calculate
another important characteristic, the nucleon momentum distribution of
the deuteron using six invariant functions instead of two
(- and -waves) in the nonrelativistic case. The comparison with the
-scaling data shows the decisive role of the function which at
500 MeV/c exceeds all other -functions (as well as the - and
-waves) for the correct description of of the deuteron in the
high-momentum region. Comparison with other calculations using - and
-waves corresponding to various nucleon-nucleon potentials is made.
Secondly, using clear indications that the high-momentum components of
in heavier nuclei are related to those in the deuteron, we develop an approach
within the natural orbital representation to calculate in -nuclei
on the basis of the deuteron momentum distribution. As examples, in
He, C and Fe are calculated and good agreement with the
-scaling data is obtained.Comment: 16 pages, 6 figures, corrected, to appear in Phys. Rev. C in February
200
Resonance Patterns in a Stadium-shaped Microcavity
We investigate resonance patterns in a stadium-shaped microcavity around
, where is the refractive index, the vacuum
wavenumber, and the radius of the circular part of the cavity. We find that
the patterns of high resonances can be classified, even though the
classical dynamics of the stadium system is chaotic. The patterns of the high
resonances are consistent with the ray dynamical consideration, and appears
as the stationary lasing modes with low pumping rate in the nonlinear dynamical
model. All resonance patterns are presented in a finite range of .Comment: 8 pages, 9 figure
The Effect of the Hall Term on the Nonlinear Evolution of the Magnetorotational Instability: I. Local Axisymmetric Simulations
The effect of the Hall term on the evolution of the magnetorotational
instability (MRI) in weakly ionized accretion disks is investigated using local
axisymmetric simulations. First, we show that the Hall term has important
effects on the MRI when the temperature and density in the disk is below a few
thousand K and between 10^13 and 10^18 cm^{-3} respectively. Such conditions
can occur in the quiescent phase of dwarf nova disks, or in the inner part
(inside 10 - 100 AU) of protoplanetary disks. When the Hall term is important,
the properties of the MRI are dependent on the direction of the magnetic field
with respect to the angular velocity vector \Omega. If the disk is threaded by
a uniform vertical field oriented in the same sense as \Omega, the axisymmetric
evolution of the MRI is an exponentially growing two-channel flow without
saturation. When the field is oppositely directed to \Omega, however, small
scale fluctuations prevent the nonlinear growth of the channel flow and the MRI
evolves into MHD turbulence. These results are anticipated from the
characteristics of the linear dispersion relation. In axisymmetry on a field
with zero-net flux, the evolution of the MRI is independent of the size of the
Hall term relative to the inductive term. The evolution in this case is
determined mostly by the effect of ohmic dissipation.Comment: 31 pages, 3 tables, 12 figures, accepted for publication in ApJ,
postscript version also available from
http://www.astro.umd.edu/~sano/publications
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