14,483 research outputs found
On Some Equivalence Relations between Incidence Calculus and Dempster-Shafer Theory of Evidence
Acoustic displacement triangle based on the individual element test
A three node, displacement based, acoustic element is developed. In order to avoid spurious rotational modes, a higher order stiffness is introduced. The higher order stiffness is developed from an incompatible strain field which computes element volume changes under nodal rotational displacements fields. The higher order strain satisfies the IET requirements, non affecting convergence. The higher order stiffness is modulated, element by element, with a factor. Thus, the displacement based formulation is capable of placing the spurious rotational modes over the range of physical compressional modes that can be accurately captured by the mesh
The Resonance Overlap and Hill Stability Criteria Revisited
We review the orbital stability of the planar circular restricted three-body
problem, in the case of massless particles initially located between both
massive bodies. We present new estimates of the resonance overlap criterion and
the Hill stability limit, and compare their predictions with detailed dynamical
maps constructed with N-body simulations. We show that the boundary between
(Hill) stable and unstable orbits is not smooth but characterized by a rich
structure generated by the superposition of different mean-motion resonances
which does not allow for a simple global expression for stability.
We propose that, for a given perturbing mass and initial eccentricity
, there are actually two critical values of the semimajor axis. All values
are
unstable in the Hill sense. The first limit is given by the Hill-stability
criterion and is a function of the eccentricity. The second limit is virtually
insensitive to the initial eccentricity, and closely resembles a new resonance
overlap condition (for circular orbits) developed in terms of the intersection
between first and second-order mean-motion resonances.Comment: 33 pages, 14 figures, accepte
The importance of scalar fields as extradimensional metric components in Kaluza-Klein models
Extradimensional models are achieving their highest popularity nowadays,
among other reasons, because they can plausible explain some standard cosmology
issues, such as the cosmological constant and hierarchy problems. In
extradimensional models, we can infer that the four-dimensional matter rises as
a geometric manifestation of the extra coordinate. In this way, although we
still cannot see the extra dimension, we can relate it to physical quantities
that are able to exert such a mechanism of matter induction in the observable
universe. In this work we propose that scalar fields are those physical
quantities. The models here presented are purely geometrical in the sense that
no matter lagrangian is assumed and even the scalar fields are contained in the
extradimensional metric. The results are capable of describing different
observable cosmic features and yield an alternative to ultimately understand
the extra dimension and the mechanism in which it is responsible for the
creation of matter in the observable universe
Configurational entropy in brane models
In this work we investigate generalized theories of gravity in the so-called
configurational entropy (CE) context. We show, by means of this
information-theoretical measure, that a stricter bound on the parameter of
brane models arises from the CE. We find that these bounds are
characterized by a valley region in the CE profile, where the entropy is
minimal. We argue that the CE measure can open a new role and an important
additional approach to select parameters in modified theories of gravitation
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