107 research outputs found
Effect of Uncertainty in Processing Parameters on the Microstructure of Single Melt Tracks Formed by Selective Laser Melting
Depinning Transition of a Two Dimensional Vortex Lattice in a Commensurate Periodic Potential
We use Monte Carlo simulations of the 2D one component Coulomb gas on a
triangular lattice, to study the depinning transition of a 2D vortex lattice in
a commensurate periodic potential. A detailed finite size scaling analysis
indicates this transition to be first order. No significant changes in behavior
were found as vortex density was varied over a wide range.Comment: 5 pages, 8 figures. Revised discussion of correlation length exponent
using a more accurate finite size scaling analysis. New figs. 5 and 6. Old
figs. 6 and 7 now figs. 7 and
Modelling the Effect of Non-Uniform Fibre Distribution on the Curing Behaviour in Resin Injection Pultrusion
Flux lattice melting and depinning in the weakly frustrated 2D XY model
Monte Carlo simulations of the frustrated 2D XY model were carried out at
small commensurate values of the frustration . For a single
transition was observed at which phase coherence (finite helicity modulus) and
vortex lattice orientational order vanish together. For a new phase in
which phase coherence is absent but orientational order persists was observed.
Where comparison is possible, the results are in detailed agreement with the
behavior of the lattice Coulomb gas model of vortices. It is argued that the
helicity modulus of the frustrated 2D XY model vanishes for any finite
temperature in the limit of weak frustration .Comment: 4 pages, RevTeX, 3 figures in separate uuencoded file The manuscript
will appear in Phys. Rev.
Fluctuation induced vortex pattern and its disordering in the fully frustrated XY model on a dice lattice
A highly degenerate family of states [proposed in PRB 63, 134503 (2001)] is
proven to really minimize the Hamiltonian of the fully frustrated XY model on a
dice lattice. The harmonic fluctuations are shown to be no consequence for the
removal of the accidental degeneracy of these states, so a particular vortex
pattern can be stabilized only by the anharmonic fluctuations. The structure of
this pattern is found and the temperature of its disordering due to the
proliferation of domain walls is estimated. The extreme smallness of the
fluctuations induced free energy of domain walls leads to the anomalous
prominence of the finite-size effects, which prevent the observation of
vortex-pattern ordering in numerical simulations. In such a situation the loss
of phase coherence may be related to the dissociation of fractional vortices
with topological charges 1/8. In a physical situation the magnetic interaction
of currents in a Josephson junction array will be a more important source for
the stabilization of a particular vortex pattern than the anharmonic
fluctuations.Comment: 20 pages, 7 figure
Multi-Scale Multiphysics Simulation of Metal L-PBF AM Process and Subsequent Mechanical Analysis
The effect of saturation on resin flow in injection pultrusion: a preliminary numerical study
Simulation of resin-impregnation, heat-transfer and cure in a resin-injection pultrusion process
Onsager Loop-Transition and First Order Flux-Line Lattice Melting in High- Superconductors
Monte-Carlo simulations in conjunction with finite-size scaling analysis are
used to investigate the -phase diagram in uniaxial anisotropic high-
superconductors, both in zero magnetic field and in intermediate magnetic
fields for various mass-anisotropies. The model we consider is the uniformly
frustrated anisotropic Villain Model. In zero magnetic field, and for all
anisotropies considered, we find one single second order phase transition,
mediated by an Onsager vortex-loop blowout. This is the superconductor-normal
metal transition.A comparison with numerical simulations and a critical scaling
analysis of the zero-field loop-transition yields the same exponent of the loop
distribution function at the critical point. In the intermediate magnetic field
regime, we find two anomalies in the specific heat. The first anomaly at a
temperature is associated with the melting transition of the flux-line
lattice. The second anomaly at a temperature is one where phase coherence
along the field direction is destroyed. We argue that in the
thermodynamic and continuum limit. Hence, there is no regime where the flux
line lattice melts into a disentangled flux-line liquid. The loss of phase
coherence parallel to the magnetic field in the sample is argued to be due to
the proliferation of closed non-field induced vortex loops on the scale of the
magnetic length in the problem, resulting in flux-line cutting and
recombination. In the flux-line liquid phase, therefore, flux-lines appear no
longer to be well defined entities. A finite-size scaling analysis of the delta
function peak specific heat anomaly at the melting transition is used to
extract the discontinuity of the entropy at the melting transition.This entropy
discontinuity is found to increase rapidly with mass-anisotropy.Comment: 22 pages, 11 figures included, to be published in Phys. Rev. B, 57
xxx (1998
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