1,262 research outputs found
Nonlinear Free Vibration Analysis of Laminated Carbon/Epoxy Curved Panels
Nonlinear frequency responses of the laminated carbon/epoxy composite curved shell panels have been investigated numerically and validated with in-house experimentation. The nonlinear responses have been computed numerically via customised computer code developed in MATLAB environment with the help of current mathematical model in conjunction with the direct iterative method. The mathematical model of the layered composite structure derived using various shear deformable kinematic models (two higher-order theories) in association with Green-Lagrange nonlinear strains. The current model includes all the nonlinear higher-order strain terms in the formulation to achieve generality. Further, the modal test has been conducted experimentally to evaluate the desired frequency values and are extracted via the transformed signals using fast Fourier transform technique. In addition, the results are computed using the simulation model developed in commercial finite element package (ANSYS) via batch input technique. Finally, numerical examples are solved for different geometrical configurations and discussed the effects of other design parameters (thickness ratio, curvature ratio and constraint condition) on the fundamental linear and nonlinear frequency responses in details
Quantum Critical Behavior and Possible Triplet Superconductivity in Electron Doped CoO2 Sheets
Density functional calculations are used to investigate the doping dependence
of the electronic structure and magnetic properties in hexagonal NaCoO.
The electronic structure is found to be highly two dimensional, even without
accounting for the structural changes associated with hydration. At the local
spin density approximation level, a weak itinerant ferromagnetic state is
predicted for all doping levels in the range to , with competing
but weaker itinerant antiferromagnetic solutions. The Fermi surface, as
expected, consists of simple rounded hexagonal cylinders, with additional small
pockets depending on the lattice parameter. Comparison with experiment
implies substantial magnetic quantum fluctuations. Based on the Fermi surface
size and the ferromagnetic tendency of this material,it is speculated that a
triplet superconducting state analogous to that in SrRuO may exist
here.Comment: 4 pages, 1 figur
A CCD photometric study of the late type contact binary EK Comae Berenices
We present CCD photometric observations of the W UMa type contact binary EK
Comae Berenices using the 2 metre telescope of Girawali Observatory,
India. The star was classified as a W UMa type binary of subtype-W by
\citet{sam1996}. The new V band photometric observations of the star reveal
that shape of the light curve has changed significantly from the one observed
by \citet{sam1996}. A detailed analysis of the light curve obtained from the
high-precision CCD photometric observations of the star indicates that EK Comae
Berenices is not a W-type but an A-type totally eclipsing W UMa contact binary.
The photometric mass ratio is determined to be 0.349 0.005. A temperature
difference of K between the components and an orbital
inclination of were obtained for the binary
system. Absolute values of masses, radii and luminosities are estimated by
means of the standard mass-luminosity relation for zero age main-sequence
stars. The star shows O'Connell effect, asymmetries in the light curve shape
around the primary and secondary maximum. The observed O'Connell effect is
explained by the presence of a hot spot on the primary component.Comment: 26 pages, 9 figures, 5 tables. Accepted for publication in New
Astronom
Testing "microscopic" theories of glass-forming liquids
We assess the validity of "microscopic" approaches of glass-forming liquids
based on the sole k nowledge of the static pair density correlations. To do so
we apply them to a benchmark provided by two liquid models that share very
similar static pair density correlation functions while disp laying distinct
temperature evolutions of their relaxation times. We find that the approaches
are unsuccessful in describing the difference in the dynamical behavior of the
two models. Our study is not exhausti ve, and we have not tested the effect of
adding corrections by including for instance three-body density correlations.
Yet, our results appear strong enough to challenge the claim that the slowd own
of relaxation in glass-forming liquids, for which it is well established that
the changes of the static structure factor with temperature are small, can be
explained by "microscopic" appr oaches only requiring the static pair density
correlations as nontrivial input.Comment: 10 pages, 7 figs; Accepted to EPJE Special Issue on The Physics of
Glasses. Arxiv version contains an addendum to the appendix which does not
appear in published versio
Reaction and Axial Vector Coupling
The reaction is studied in the region of low
to investigate the effect of deuteron structure and width of the
resonance on the differential cross section. The results are used to extract
the axial vector coupling from the experimental data on
this reaction. The possibility to determine this coupling from electroweak
interaction experiments with high intensity electron accelerators is discussed.Comment: 14 pages, REVTEX, 5 figure
Non-vacuum Solutions of Bianchi Type VI_0 Universe in f(R) Gravity
In this paper, we solve the field equations in metric f(R) gravity for
Bianchi type VI_0 spacetime and discuss evolution of the expanding universe. We
find two types of non-vacuum solutions by taking isotropic and anisotropic
fluids as the source of matter and dark energy. The physical behavior of these
solutions is analyzed and compared in the future evolution with the help of
some physical and geometrical parameters. It is concluded that in the presence
of isotropic fluid, the model has singularity at and represents
continuously expanding shearing universe currently entering into phantom phase.
In anisotropic fluid, the model has no initial singularity and exhibits the
uniform accelerating expansion. However, the spacetime does not achieve
isotropy as in both of these solutions.Comment: 20 pages, 5 figures, accepted for publication in Astrophys. Space Sc
Surface water numerical modelling for the Gloucester subregion. Product 2.6.1 for the Gloucester subregion from the Northern Sydney Basin Bioregional Assessment
No abstract available
Surface water numerical modelling for the Gloucester subregion. Product 2.6.1 for the Gloucester subregion from the Northern Sydney Basin Bioregional Assessment
No abstract available
Order parameter symmetry in ferromagnetic superconductors
We analyze the symmetry and the nodal structure of the superconducting order
parameter in a cubic ferromagnet, such as ZrZn. We demonstrate how the
order parameter symmetry evolves when the electromagnetic interaction of the
conduction electrons with the internal magnetic induction and the spin-orbit
coupling are taken into account. These interactions break the cubic symmetry
and lift the degeneracy of the order parameter. It is shown that the order
parameter which appears immediately below the critical temperature has two
components, and its symmetry is described by {\em co-representations} of the
magnetic point groups. This allows us to make predictions about the location of
the gap nodes.Comment: 12 pages, ReVTeX, submitted to PR
Infrared generation in low-dimensional semiconductor heterostructures via quantum coherence
A new scheme for infrared generation without population inversion between
subbands in quantum-well and quantum-dot lasers is presented and documented by
detailed calculations. The scheme is based on the simultaneous generation at
three frequencies: optical lasing at the two interband transitions which take
place simultaneously, in the same active region, and serve as the coherent
drive for the IR field. This mechanism for frequency down-conversion does not
rely upon any ad hoc assumptions of long-lived coherences in the semiconductor
active medium. And it should work efficiently at room temperature with
injection current pumping. For optimized waveguide and cavity parameters, the
intrinsic efficiency of the down-conversion process can reach the limiting
quantum value corresponding to one infrared photon per one optical photon. Due
to the parametric nature of IR generation, the proposed inversionless scheme is
especially promising for long-wavelength (far- infrared) operation.Comment: 4 pages, 1 Postscript figure, Revtex style. Replacement corrects a
printing error in the authors fiel
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