84,502 research outputs found
Dynamical growth of the hadron bubbles during the quark-hadron phase transition
The rate of dynamical growth of the hadron bubbles in a supercooled baryon
free quark-gluon plasma, is evaluated by solving the equations of relativistic
fluid dynamics in all regions. For a non-viscous plasma, this dynamical growth
rate is found to depend only on the range of correlation of order
parameter fluctuation, and the radius of the critical hadron bubble, the
two length scales relevant for the description of the critical phenomena.
Further, it is shown that the dynamical prefactor acquires an additive
component when the medium becomes viscous. Interestingly, under certain
reasonable assumption for the velocity of the sound in the medium around the
saddle configuration, the viscous and the non-viscous parts of the prefactor
are found to be similar to the results obtained by Csernai-Kapusta and
Ruggeri-Friedman (for the case of zero viscosity) respectively.Comment: RevTeX, 11 pages including 4 Postscript figures, major revision,
Version without section IV is to appear in Physical Review
Ground temperature measurement by PRT-5 for maps experiment
A simple algorithm and computer program were developed for determining the actual surface temperature from the effective brightness temperature as measured remotely by a radiation thermometer called PRT-5. This procedure allows the computation of atmospheric correction to the effective brightness temperature without performing detailed radiative transfer calculations. Model radiative transfer calculations were performed to compute atmospheric corrections for several values of the surface and atmospheric parameters individually and in combination. Polynomial regressions were performed between the magnitudes or deviations of these parameters and the corresponding computed corrections to establish simple analytical relations between them. Analytical relations were also developed to represent combined correction for simultaneous variation of parameters in terms of their individual corrections
Evaluation of upwelling infrared radiance from earth's atmosphere
Basic equations for calculating the upwelling atmospheric radiation are presented which account for various sources of radiation coming out at the top of the atmosphere. The theoretical formulation of the transmittance models (line-by-line and quasi-random band model) and the computational procedures used for the evaluation of the transmittance and radiance are discussed in detail. By employing the Lorentz line-by-line and quasi-random computer programs, model calculations were made to determine the upwelling radiance and signal change in the wave number interval of CO fundamental band. These results are useful in determining the effects of different interfering molecules, water vapor profiles, ground temperatures, and ground emittances on the upwelling radiance and signal change. This information is of vital importance in establishing the feasibility of measuring the concentrations of pollutants in the atmosphere from a gas filter correlation instrument flown on an aircraft or mounted on a satellite
Gap solitons with null-scattering
We study excitation of gap solitons under the conditions of coherent perfect
absorption (CPA). Our system consists of a symmetric periodic structure with
alternating Kerr nonlinear and linear layers, illuminated from both the ends.
We show near-total transfer of incident light energy into the gap solitons
resulting in null-scattering. We also report on the nonlinear super-scattering
(SS) states. Both the CPA and the SS states are shown to be characterized by
typical field distributions. Both the exact and the approximate results (based
on nonlinear characteristic matrix method) are presented, which show good
agreement
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