We evaluate the thermodynamic critical angular velocity Ωc(T ) for creation of a vortex of lowest quantized angular momentum in a strictly two-dimensional Bose gas at temperature T , using a mean-field two-fluid model for the condensate and the thermal cloud. Our results show that (i) a Thomas-Fermi description of the condensate badly fails in predicting the particle density profiles and the en...

The interaction of a vortex pair with a premixed flame serves as an important prototype for premixed turbulent combustion. In this study, we investigate the interaction of a counter-rotating vortex pair with an initially flat premixed methane flame. We compare computational solutions obtained using a timedependent, two-dimensional adaptive low Mach number combustion algorithm that incorporates ...

Abstract In the London limit of the Ginzburg-Landau theory (Abelian Higgs model), vortex dipoles (small vortex loops) are treated as a grand canonical ensemble in the dilute gas approximation. The summation over these objects with the most general rotationand translation invariant measure of integration over their shapes leads to effective sine-Gordon theories of the dual fields. The representa...

We prove separator theorems in which the size of the separator is minimized with respect to non-negative vertex costs. We show that for any planar graph G there exists a vertex separator of total vertex cost at most c q P v2V (G) (cost(v)) 2 and that this bound is optimal within a constant factor. Moreover such a separator can be found in linear time. This theorem implies a variety of other sep...

We address the problem of nding a minimal separator in a di rected acyclic graph DAG namely nding a set Z of nodes that d separates a given pair of nodes such that no proper subset of Z d separates that pair We analyze several versions of this problem and o er polynomial algorithms for each These include nding a minimal separator from a restricted set of nodes nding a minimum cost separator and...

Two independent beam stoppers have been developed for improving the separation of gas-filled recoil ion separator GARIS-II. Performance evaluation these supplemental was performed by using 208Pb (18O,3n)223Th reaction. A160-fold enhancement signal-to-noise ratio at GARIS-II focal plane observed.

This paper illustrates the mechanism of U-shaped vortex formation which is found both by experiment and DNS. The main goal of this paper is to explain how the U-shaped vortex is formed and further develops. According to the results obtained by our direct numerical simulation with high order accuracy, the U-shaped vortex is part of the coherent vortex structure and is actually the tertiary strea...

We present a framework for studying vortex lattice patterns and their structural transitions, using the Parrinello–Rahman (PR) method for molecular-dynamics (MD) simulations. Assuming an interaction between vortices derived from a Ginzburg–Landau field-theoretic context, we extract the ground-state of a “vortex gas” using the PR-MD technique and find it to be a triangular pattern. Other pattern...

We have studied the dynamics of large vortex lattices in a dilute-gas Bose-Einstein condensate. While undisturbed lattices have a regular hexagonal structure, large-amplitude quadrupolar shape oscillations of the condensate are shown to induce a wealth of nonequilibrium lattice dynamics. When exciting an m=-2 mode, we observe shifting of lattice planes, changes of lattice structure, and sheetli...