16,981 research outputs found
Continuous-flow variable-density wind tunnel facilities
Unique features of wind tunnel facilities at Jet Propulsion Laboratory permit variety of conventional and novel tests to be performed at supersonic and hypersonic speeds. Facilities and operations are described
Non-spherical sources of static gravitational fields: investigating the boundaries of the no-hair theorem
A new, globally regular model describing a static, non spherical gravitating
object in General Relativity is presented. The model is composed by a vacuum
Weyl--Levi-Civita special field - the so called gamma metric - generated by a
regular static distribution of mass-energy. Standard requirements of physical
reasonableness such as, energy, matching and regularity conditions are
satisfied. The model is used as a toy in investigating various issues related
to the directional behavior of naked singularities in static spacetimes and the
blackhole (Schwarschild) limit.Comment: 10 pages, 2 figure
Collapsing Spheres Satisfying An "Euclidean Condition"
We study the general properties of fluid spheres satisfying the heuristic
assumption that their areas and proper radius are equal (the Euclidean
condition). Dissipative and non-dissipative models are considered. In the
latter case, all models are necessarily geodesic and a subclass of the
Lemaitre-Tolman-Bondi solution is obtained. In the dissipative case solutions
are non-geodesic and are characterized by the fact that all non-gravitational
forces acting on any fluid element produces a radial three-acceleration
independent on its inertial mass.Comment: 1o pages, Latex. Title changed and text shortened to fit the version
to appear in Gen.Rel.Grav
Static cylindrical symmetry and conformal flatness
We present the whole set of equations with regularity and matching conditions
required for the description of physically meaningful static cylindrically
symmmetric distributions of matter, smoothly matched to Levi-Civita vacuum
spacetime. It is shown that the conformally flat solution with equal principal
stresses represents an incompressible fluid. It is also proved that any
conformally flat cylindrically symmetric static source cannot be matched
through Darmois conditions to the Levi-Civita spacetime. Further evidence is
given that when the Newtonian mass per unit length reaches 1/2 the spacetime
has plane symmetry.Comment: 13 pages, Late
Dalitz plot slope parameters for decays and two particle interference
We study the possible distortion of phase-space in the decays , which may result from final state interference among the decay products.
Such distortion may influence the values of slope parameters extracted from the
Dalitz plot distribution of these decays. We comment on the consequences on the
magnitude of violation of the rule in these decays.Comment: 17 pages, LaTex2e, 6 figures, v2 authors' affiliation modified, to
appear in Mod. Phys. Lett.
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