1,240 research outputs found
Radiating and non-radiating sources in elasticity
In this work, we study the inverse source problem of a fixed frequency for
the Navier's equation. We investigate that nonradiating external forces. If the
support of such a force has a convex or non-convex corner or edge on their
boundary, the force must be vanishing there. The vanishing property at corners
and edges holds also for sufficiently smooth transmission eigenfunctions in
elasticity. The idea originates from the enclosure method: The energy identity
and new type exponential solutions for the Navier's equation.Comment: 17 page
Effects of Bulk Viscosity on Cosmological Evolution
The effect of bulk viscisity on the evolution of the homogeneous and
isotropic cosmological models is considered. Solutions are found, with a
barotropic equation of state, and a viscosity coefficient that is proportional
to a power of the energy density of the universe. For flat space, power law
expansions, related to extended inflation are found as well as exponential
solutions, related to old inflation; also a solution with expansion that is an
exponential of an exponential of the time is found.Comment: 8 pages, latex, no figure
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