469,525 research outputs found
Installing fiber insulation
A method for installing fragile, high temperature insulation batting in an elongated cavity or in a resilient wire sleeve to form a resilient seal. The batting is preformed to rough dimensions and wrapped in a plastic film, the film being of a material which is fugitive at a high temperature. The film is heat sealed and trimmed to form a snugly fit skin which overlaps at least at one end to permit attachment of a pull cord. The film absorbs the tensile force of pulling the film enclosed batting through the cavity or wire mesh sleeve and is subsequently driven off by high temperature baking, leaving only the insulation in the cavity or wire mesh sleeve
Optical properties of Born-Infeld-dilaton-Lifshitz holographic superconductors
In this paper, we first study the Lifshitz-dilaton holographic
superconductors with nonlinear Born-Infeld (BI) gauge field and obtain the
critical temperature of the system for different values of Lifshitz dynamical
exponent, , and nonlinear parameter . We find that for fixed value of
, the critical temperature decreases with increasing . This indicates
that the increase of anisotropy between space and time prevents the phase
transition. Also, for fixed value of , the critical temperature decrease
with increasing . Then, we investigate the optical properties of () and
()-dimensional BI-Lifshitz holographic superconductors in the the presence
of dilaton field. We explore the refractive index of the system. For and
-dimensional holographic superconductor, we observe negative real part
for permittivity as frequency decreases.
Thus, in low frequency region our superconductor exhibit metamaterial property.
This behaviour is independent of the nonlinear parameter and can be seen for
either linear () and nonlinear () electrodynamics. Interestingly,
for ()-dimensional Lifshitz-dilaton holographic superconductors, we
observe metamaterial behavior neither in the presence of linear nor nonlinear
electrodynamics.Comment: 11 pages, 9 figures (including subfigures), some references added in
V
theory and geometric origin of the dark sector in Horava-Lifshitz gravity
Inclusion of term in the action of Horava-Lifshitz quantum gravity
with projectability but without detailed balance condition is investigated,
where denotes the 3-spatial dimensional Ricci scalar. Conditions for the
spin-0 graviton to be free of ghosts and instability are studied. The
requirement that the theory reduce to general relativity in the IR makes the
scalar mode unstable in the Minkowski background but stable in the de Sitter.
It is remarkable that the dark sector, dark matter and dark energy, of the
universe has a naturally geometric origin in such a setup. Bouncing universes
can also be constructed. Scalar perturbations in the FRW backgrounds with
non-zero curvature are presented.Comment: Mod. Phys. Lett. A26, 387-398 (2011
Dynamic modeling of spacecraft in a collisionless plasma
A new computational model is described which can simulate the charging of complex geometrical objects in three dimensions. Two sample calculations are presented. In the first problem, the capacitance to infinity of a complex object similar to a satellite with solar array paddles is calculated. The second problem concerns the dynamical charging of a conducting cube partially covered with a thin dielectric film. In this calculation, the photoemission results in differential charging of the object
Analysis of the form-factors with light-cone QCD sum rules
In this article, we study the , ,
form-factors with the light-cone QCD sum rules, where the -meson light-cone
distribution amplitudes are used. In calculations, we observe that the
line-shapes of the -meson light-cone distribution amplitude
have significant impacts on the values of the form-factors, and expect to
obtain severe constraints on the parameters of the -meson light-cone
distribution amplitudes from the experimental data in the future.Comment: 19 pages, 6 figures, slight revisio
An Exactly Solvable Model of Generalized Spin Ladder
A detailed study of an spin ladder model is given. The ladder
consists of plaquettes formed by nearest neighbor rungs with all possible
SU(2)-invariant interactions. For properly chosen coupling constants, the model
is shown to be integrable in the sense that the quantum Yang-Baxter equation
holds and one has an infinite number of conserved quantities. The R-matrix and
L-operator associated with the model Hamiltonian are given in a limiting case.
It is shown that after a simple transformation, the model can be solved via a
Bethe ansatz. The phase diagram of the ground state is exactly derived using
the Bethe ansatz equation
Spectral Lags Obtained by CCF of Smoothed Lightcurves
We present a new technique to calculate the spectral lags of gamma-ray bursts
(GRBs). Unlike previous processing methods, we first smooth the light curves of
gamma-ray bursts in high and low energy bands using the "Loess" filter, then,
we directly define the spectral lags as such to maximize the cross-correlation
function (CCF) between two smoothed light curves. This method is suitable for
various shapes of CCF; it effectively avoids the errors caused by manual
selections for the fitting function and fitting interval. Using the method, we
have carefully measured the spectral lags of individual pulses contained in
BAT/Swift gamma-ray bursts with known redshifts, and confirmed the
anti-correlation between the spectral lag and the isotropy luminosity. The
distribution of spectral lags can be well fitted by four Gaussian components,
with the centroids at 0.03 s, 0.09 s, 0.15 s, and 0.21 s, respectively. We find
that some spectral lags of the multi-peak GRBs seem to evolve with time
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