7,563 research outputs found
Three-dimensional model with the Chern-Simons term
We investigate the influence of the Chern-Simons term coupled to the
three-dimensional model. This term endows vortices with an internal
angular momentum and thus gives them arbitrary statistics. The Chern-Simons
term for the model takes an integer value which can be written as a sum
over all vortex lines of the product of the vortex charge and the winding
number of the internal phase angle along that vortex line. We have used the
Monte-Carlo method to study the three-dimensional model with the
Chern-Simons term. Our findings suggest that this model belongs to the
universality class with the critical temperature growing with increasing
internal angular momentum.Comment: 15 pages, uuencoded postscript fil
Propagation and reconstruction of re-entry uncertainties using continuity equation and simplicial interpolation
This work proposes a continuum-based approach for the propagation of
uncertainties in the initial conditions and parameters for the analysis and
prediction of spacecraft re-entries. Using the continuity equation together
with the re-entry dynamics, the joint probability distribution of the
uncertainties is propagated in time for specific sampled points. At each time
instant, the joint probability distribution function is then reconstructed from
the scattered data using a gradient-enhanced linear interpolation based on a
simplicial representation of the state space. Uncertainties in the initial
conditions at re-entry and in the ballistic coefficient for three
representative test cases are considered: a three-state and a six-state steep
Earth re-entry and a six-state unguided lifting entry at Mars. The paper shows
the comparison of the proposed method with Monte Carlo based techniques in
terms of quality of the obtained marginal distributions and runtime as a
function of the number of samples used
The superconductor-insulator transition in 2D dirty boson systems
Universal properties of the zero temperature superconductor-insulator
transition in two-dimensional amorphous films are studied by extensive Monte
Carlo simulations of bosons in a disordered medium. We report results for both
short-range and long-range Coulomb interactions for several different points in
parameter space. In all cases we observe a transition from a superconducting
phase to an insulating Bose glass phase. {}From finite-size scaling of our
Monte Carlo data we determine the universal conductivity and the
critical exponents at the transition. The result for bosons with long-range Coulomb interaction is roughly consistent
with experiments reported so far. We also find for bosons with short-range interactions.Comment: Revtex 3.0, 54 pages, 17 figures included, UBCTP-93-01
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