3,727 research outputs found
Absolute and convective instabilities in non-local active-dissipative equations arising in the modelling of thin liquid films
This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.Absolute and convective instabilities in a non-local model that arises in the analysis of thin-film
flows over flat or corrugated walls in the presence of an applied electric field are discussed. Electrified liquid
films arise, for example, in coating processes where liquid films are deposited onto a target surfaces with a
view to producing an evenly coating layer. In practice, the target surface, or substrate, may be irregular in shape and feature corrugations or indentations. This may lead to non-uniformities in the thickness of the coating layer. Attempts to mitigate film-surface irregularities can be made using, for example, electric fields.
We analyse the stability of such thin-film flows and show that if the amplitude of the wall corrugations and/or the strength of the applied electric field is increased the convectively unstable flow undergoes a transition to an absolutely unstable flow
The solvability of groups with nilpotent minimal coverings
A covering of a group is a finite set of proper subgroups whose union is the
whole group. A covering is minimal if there is no covering of smaller
cardinality, and it is nilpotent if all its members are nilpotent subgroups. We
complete a proof that every group that has a nilpotent minimal covering is
solvable, starting from the previously known result that a minimal
counterexample is an almost simple finite group
Antinucleus Production at RHIC
Light antinuclei may be formed in relativistic heavy ion collisions via final
state coalescence of antinucleons. The yields of antinuclei are sensitive to
primordial antinucleon production, the volume of the system at kinetic
freeze-out, and space-momentum correlations among antinucleons at freeze-out.
We report here preliminary STAR results on antideuteron and antihelion
production in 130A GeV Au+Au collisions. These results are examined in a
coalescence framework to elucidate the space-time structure of the antinucleon
source.Comment: 4 pages, 3 figures, talk given at Quark Matter 200
Confidence regions for the multinomial parameter with small sample size
Consider the observation of n iid realizations of an experiment with d>1
possible outcomes, which corresponds to a single observation of a multinomial
distribution M(n,p) where p is an unknown discrete distribution on {1,...,d}.
In many applications, the construction of a confidence region for p when n is
small is crucial. This concrete challenging problem has a long history. It is
well known that the confidence regions built from asymptotic statistics do not
have good coverage when n is small. On the other hand, most available methods
providing non-asymptotic regions with controlled coverage are limited to the
binomial case d=2. In the present work, we propose a new method valid for any
d>1. This method provides confidence regions with controlled coverage and small
volume, and consists of the inversion of the "covering collection"' associated
with level-sets of the likelihood. The behavior when d/n tends to infinity
remains an interesting open problem beyond the scope of this work.Comment: Accepted for publication in Journal of the American Statistical
Association (JASA
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Absolute and convective instabilities in non-local active-dissipative equations arising in the modelling of thin liquid films
This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.Absolute and convective instabilities in a non-local model that arises in the analysis of thin-film
flows over flat or corrugated walls in the presence of an applied electric field are discussed. Electrified liquid
films arise, for example, in coating processes where liquid films are deposited onto a target surfaces with a
view to producing an evenly coating layer. In practice, the target surface, or substrate, may be irregular in
shape and feature corrugations or indentations. This may lead to non-uniformities in the thickness of the
coating layer. Attempts to mitigate film-surface irregularities can be made using, for example, electric fields.
We analyse the stability of such thin-film flows and show that if the amplitude of the wall corrugations
and/or the strength of the applied electric field is increased the convectively unstable flow undergoes a
transition to an absolutely unstable flow
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