4,623 research outputs found
Salt stabilizer for preventing chlorine depletion and increasing shelf-life of potable water - A concept
Proposed concept, based on law of mass action uses addition of salt to increase chlorine ions produced in sodium hydrochlorite solutions, thereby increasing solution shelf-life. This technique is not costly. Usefulness will be determined by acceptability of salt in product undergoing long shelf-life
Environmental test planning, selection and standardization aids available
Requirements for instrumentation, equipment, and methods to be used in conducting environmental tests on components intended for use by a wide variety of technical personnel of different educational backgrounds, experience, and interests is announced
Attractor solutions for general hessence dark energy
As a candidate for the dark energy, the hessence model has been recently
introduced. We discuss the critical points of this model in almost general
case, that is for arbitrary hessence potential and almost arbitrary
hessence-background matter interaction. It is shown that in all models, there
always exist some stable late-time attractors. It is shown that our general
results coincide with those solutions obtained earlier for special cases, but
some of them are new. These new solutions have two unique characteristics.
First the hessence field has finite value in these solutions and second, their
stabilities depend on the second derivative of the hessence potential.Comment: 11 pages. Add some explanations about the autonomousity of the
equations, and also a conclusion section was added. To appear in Phys. Rev. D
(2006
Some aspects of thermal inflation: the finite temperature potential and topological defects
Currently favoured extensions of the Standard Model typically contain `flaton
fields' defined as fields with large vacuum expectation values (vevs) and
almost flat potentials. If a flaton field is trapped at the origin in the early
universe, one expects `thermal inflation' to take place before it rolls away to
the true vacuum, because the finite-temperature correction to the potential
will hold it at the origin until the temperature falls below 1\TeV or so. In
the first part of the paper, that expectation is confirmed by an estimate of
the finite temperature corrections and of the tunneling rate to the true
vacuum, paying careful attention to the validity of the approximations that are
used. The second part of the paper considers topological defects which may be
produced at the end of an era of thermal inflation. If the flaton fields
associated with the era are GUT higgs fields, then its end corresponds to the
GUT phase transition. In that case monopoles (as well as GUT higgs particles)
will have to be diluted by a second era of thermal inflation. Such an era will
not affect the cosmology of GUT strings, for which the crucial parameter is the
string mass per unit length. Because of the flat Higgs potential, the GUT
symmetry breaking scale required for the strings to be a candidate for the
origin of large scale structure and the cmb anisotropy is about three times
bigger than usual, but given the uncertainties it is still compatible with the
one required by the unification of the Standard Model gauge couplings. The
cosmology of textures and of global monopoles is unaffected by the flatness of
the potential.Comment: 40 pages, LaTeX with epsf macro, 1 figure, preprint number correcte
Use of LARS system for the quantitative determination of smoke plume lateral diffusion coefficients from ERTS images of Virginia
A technique for measuring smoke plume of large industrial sources observed by satellite using LARSYS is proposed. A Gaussian plume model is described, integrated in the vertical, and inverted to yield a form for the lateral diffusion coefficient, Ky. Given u, wind speed; y sub l, the horizontal distance of a line of constant brightness from the plume symmetry axis a distance x sub l, downstream from reference point at x=x sub 2, y=0, then K sub y = u ((y sub 1) to the 2nd power)/2 x sub 1 1n (x sub 2/x sub 1). The technique is applied to a plume from a power plant at Chester, Virginia, imaged August 31, 1973 by LANDSAT I. The plume bends slightly to the left 4.3 km from the source and estimates yield Ky of 28 sq m/sec near the source, and 19 sq m/sec beyond the bend. Maximum ground concentrations are estimated between 32 and 64 ug/cu m. Existing meteorological data would not explain such concentrations
Running-mass models of inflation, and their observational constraints
If the inflaton sector is described by softly broken supersymmetry, and the
inflaton has unsuppressed couplings, the inflaton mass will run strongly with
scale. Four types of model are possible. The prediction for the spectral index
involves two parameters, while the COBE normalization involves a third, all of
them calculable functions of the relevant masses and couplings. A crude
estimate is made of the region of parameter space allowed by present
observation.Comment: Latex file, 20 pages, 11 figures, uses epsf.sty. Comment on the
observation of the spectral index scale dependence added; Fig. 3-6 improve
Curvaton reheating: an application to braneworld inflation
The curvaton was introduced recently as a distinct inflationary mechanism for
generating adiabatic density perturbations. Implicit in that scenario is that
the curvaton offers a new mechanism for reheating after inflation, as it is a
form of energy density not diluted by the inflationary expansion. We consider
curvaton reheating in the context of a braneworld inflation model, {\em steep
inflation}, which features a novel use of the braneworld to give a new
mechanism for ending inflation. The original steep inflation model featured
reheating by gravitational particle production, but the inefficiency of that
process brings observational difficulties. We demonstrate here that the
phenomenology of steep inflation is much improved by curvaton reheating.Comment: 8 pages RevTeX4 file with two figures incorporated. Improved
referencing, matches PRD accepted versio
Symmetries for generating string cosmologies
We discuss the symmetry properties of the low-energy effective action of the
type IIB superstring that may be employed to derive four-dimensional solutions.
A truncated effective action, compactified on a six-torus, but including both
Neveu/Schwarz-Neveu/Schwarz and Ramond-Ramond field strengths, can be expressed
as a non-linear sigma model which is invariant under global SL(3,R)
transformations. This group contains as a sub-group the SL(2,R) symmetry of the
ten-dimensional theory and a discrete Z2 reflection symmetry which leads to a
further SL(2,R) sub-group. The symmetries are employed to analyse a general
class of spatially homogeneous cosmological solutions with non-trivial
Ramond-Ramond fields.Comment: Substantially extended version with new sections on further
symmetries and anisotropic cosmological solutions. New title. To appear in
Physical Review D. 13 pages, LaTeX, no figure
Interactions between Cosmic Strings: An Analytical Study
We derive analytic expressions for the interaction energy between two general
cosmic strings as the function of their relative orientation and the
ratio of the coupling constants in the model. The results are relevant to the
statistic description of strings away from critical coupling and shed some
light on the mechanisms involved in string formation and the evolution of
string networks.Comment: 31 pages,REVTEX, Imperial/TP/93-94/3
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