47 research outputs found
Homogeneous Bubble Nucleation driven by local hot spots: a Molecular Dynamics Study
We report a Molecular Dynamics study of homogenous bubble nucleation in a
Lennard-Jones fluid. The rate of bubble nucleation is estimated using
forward-flux sampling (FFS). We find that cavitation starts with compact
bubbles rather than with ramified structures as had been suggested by Shen and
Debenedetti (J. Chem. Phys. 111:3581, 1999). Our estimate of the
bubble-nucleation rate is higher than predicted on the basis of Classical
Nucleation Theory (CNT). Our simulations show that local temperature
fluctuations correlate strongly with subsequent bubble formation - this
mechanism is not taken into account in CNT
Lattice Boltzmann simulations of soft matter systems
This article concerns numerical simulations of the dynamics of particles
immersed in a continuum solvent. As prototypical systems, we consider colloidal
dispersions of spherical particles and solutions of uncharged polymers. After a
brief explanation of the concept of hydrodynamic interactions, we give a
general overview over the various simulation methods that have been developed
to cope with the resulting computational problems. We then focus on the
approach we have developed, which couples a system of particles to a lattice
Boltzmann model representing the solvent degrees of freedom. The standard D3Q19
lattice Boltzmann model is derived and explained in depth, followed by a
detailed discussion of complementary methods for the coupling of solvent and
solute. Colloidal dispersions are best described in terms of extended particles
with appropriate boundary conditions at the surfaces, while particles with
internal degrees of freedom are easier to simulate as an arrangement of mass
points with frictional coupling to the solvent. In both cases, particular care
has been taken to simulate thermal fluctuations in a consistent way. The
usefulness of this methodology is illustrated by studies from our own research,
where the dynamics of colloidal and polymeric systems has been investigated in
both equilibrium and nonequilibrium situations.Comment: Review article, submitted to Advances in Polymer Science. 16 figures,
76 page
Zero to eight : young children and their internet use
EU Kids Online has spent seven years
investigating 9-16 year olds’ engagement with
the internet, focusing on the benefits and risks
of children’s internet use. While this meant
examining the experiences of much younger
children than had been researched before EU
Kids Online began its work in 2006, there is
now a critical need for information about the
internet-related behaviours of 0-8 year olds.
EU Kids Online’s research shows that children
are now going online at a younger and
younger age, and that young children’s “lack
of technical, critical and social skills may pose
[a greater] risk” (Livingstone et al, 2011, p. 3).peer-reviewe
Geographical imaginations, politics of hospitality and the media in the European refugee crisis
acceptedVersionPeer reviewe
Yields and greenhouse gas emissions of cultivation of red clover-grass leys as assessed by LCA when fertilised with organic or mineral fertilisers.
Red clover-grass leys were fertilized with cow manure or with chemical fertilizers. The yields were lower with organic fertilizers, but nevertheless the GHG emissions were lower per tonne of biomass in organic than in conventional conditions, even when the extra need for cultivation area to gain equal amounts of yield was considered. Results of a 4 year field experiment in Southern Finland