5,104 research outputs found
An alternative theoretical approach to describe planetary systems through a Schrodinger-type diffusion equation
In the present work we show that planetary mean distances can be calculated
with the help of a Schrodinger-type diffusion equation. The obtained results
are shown to agree with the observed orbits of all the planets and of the
asteroid belt in the solar system, with only three empty states. Furthermore,
the equation solutions predict a fundamental orbit at 0.05 AU from solar-type
stars, a result confirmed by recent discoveries. In contrast to other similar
approaches previously presented in the literature, we take into account the
flatness of the solar system, by considering the flat solutions of the
Schrodinger-type equation. The model has just one input parameter, given by the
mean distance of Mercury.Comment: 6 pages. Version accepted for publication in Chaos, Solitons &
Fractal
On geometry-dependent vortex stability and topological spin excitations on curved surfaces with cylindrical symmetry
We study the Heisenberg Model on cylindrically symmetric curved surfaces. Two
kinds of excitations are considered. The first is given by the isotropic
regime, yielding the sine-Gordon equation and -solitons are predicted. The
second one is given by the XY model, leading to a vortex turning around the
surface. Helical states are also considered, however, topological arguments can
not be used to ensure its stability. The energy and the anisotropy parameter
which stabilizes the vortex state are explicitly calculated for two surfaces:
catenoid and hyperboloid. The results show that the anisotropy and the vortex
energy depends on the underlying geometry.Comment: 10 pages, 2 figures, Accepted for publication in Phys. Lett A (2013
Generation of Superposition States and Charge-Qubit Relaxation Probing in a Circuit
We demonstrate how a superposition of coherent states can be generated for a
microwave field inside a coplanar transmission line coupled to a single
superconducting charge qubit, with the addition of a single classical magnetic
pulse for chirping of the qubit transition frequency. We show how the qubit
dephasing induces decoherence on the field superposition state, and how it can
be probed by the qubit charge detection. The character of the charge qubit
relaxation process itself is imprinted in the field state decoherence profile.Comment: 6 pages, 4 figure
A proposal for a generalized canonical osp(1,2) quantization of dynamical systems with constraints
The aim of this paper is to consider a possibility of constructing for
arbitrary dynamical systems with first-class constraints a generalized
canonical quantization method based on the osp(1,2) supersymmetry principle.
This proposal can be considered as a counterpart to the osp(1,2)-covariant
Lagrangian quantization method introduced recently by Geyer, Lavrov and
M\"ulsch. The gauge dependence of Green's functions is studied. It is shown
that if the parameter m^2 of the osp(1,2) superalgebra is not equal to zero
then the vacuum functional and S-matrix depend on the gauge. In the limit the gauge independence of vacuum functional and S - matrix are restored. The
Ward identities related to the osp(1,2) symmetry are derived.Comment: Revised version. To appear in Mod.Phys.Lett.
How hole defects modify vortex dynamics in ferromagnetic nanodisks
Defects introduced in ferromagnetic nanodisks may deeply affect the structure
and dynamics of stable vortex-like magnetization. Here, analytical techniques
are used for studying, among other dynamical aspects, how a small cylindrical
cavity modify the oscillatory modes of the vortex. For instance, we have
realized that if the vortex is nucleated out from the hole its gyrotropic
frequencies are shifted below. Modifications become even more pronounced when
the vortex core is partially or completely captured by the hole. In these
cases, the gyrovector can be partially or completely suppressed, so that the
associated frequencies increase considerably, say, from some times to several
powers. Possible relevance of our results for understanding other aspects of
vortex dynamics in the presence of cavities and/or structural defects are also
discussed.Comment: 9 pages, 4 page
A new methodology to predict damage tolerance based on compliance via global-local analysis
Over the years several design philosophies to fatigue developed in order to combine structural safety and economy to manufacturing and operating aircraft process. The safe-life approach, which consists of designing and manufacturing a safe aeronautical structure throughout its useful life, results in factors that oversize the structural elements, preventing the possibility of failure and evidently leading to high design costs. On the other hand, the approach based on the damage tolerance concept, in which it is assumed that the structure, even whether damaged, is able to withstand the actions for which it was designed until the detection of a crack due to fatigue or other defects during its operation. Here, we propose a new methodology to the damage tolerance problem in which two-dimensional global-local analysis at different levels of external requests will be made by means of compliance, aimed at finding a relationship between fatigue life and the Paris constant. Moreover, the BemCracker2D program for simulating two-dimensional crack growth is used. This methodology has been proved to be an efficient and applied alternative in the damage tolerance analysis
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