7,826 research outputs found
Accurate simulation estimates of phase behaviour in ternary mixtures with prescribed composition
This paper describes an isobaric semi-grand canonical ensemble Monte Carlo
scheme for the accurate study of phase behaviour in ternary fluid mixtures
under the experimentally relevant conditions of prescribed pressure,
temperature and overall composition. It is shown how to tune the relative
chemical potentials of the individual components to target some requisite
overall composition and how, in regions of phase coexistence, to extract
accurate estimates for the compositions and phase fractions of individual
coexisting phases. The method is illustrated by tracking a path through the
composition space of a model ternary Lennard-Jones mixture.Comment: 6 pages, 3 figure
Supply chain temple of resilience
In March 2011, an earthquake and tsunami hit the north-eastern coastline of Japan. Honda, Toyota, Nissan and Subaru all had plants in or close to the affected region, and were forced to close them
Simulation studies of fluid critical behaviour
We review and discuss recent advances in the simulation of bulk critical
phenomena in model fluids. In particular we emphasise the extensions to
finite-size scaling theory needed to cope with the lack of symmetry between
coexisting fluid phases. The consequences of this asymmetry for simulation
measurements of quantities such as the particle density and the heat capacity
are pointed out and the relationship to experiment is discussed. A general
simulation strategy based on the finite-size scaling theory is described and
its utility illustrated via Monte-Carlo studies of the Lennard-Jones fluid and
a two-dimensional spin fluid model. Recent applications to critical polymer
blends and solutions are also briefly reviewed. Finally we consider the outlook
for future simulation work in the field.Comment: 35 pages Revtex, 11 eps figures. Review article to appear in J.
Phys.: Condens. Matte
A non-equilibrium Monte Carlo approach to potential refinement in inverse problems
The inverse problem for a disordered system involves determining the
interparticle interaction parameters consistent with a given set of
experimental data. Recently, Rutledge has shown (Phys. Rev. E63, 021111 (2001))
that such problems can be generally expressed in terms of a grand canonical
ensemble of polydisperse particles. Within this framework, one identifies a
polydisperse attribute (`pseudo-species') corresponding to some
appropriate generalized coordinate of the system to hand. Associated with this
attribute is a composition distribution measuring the number
of particles of each species. Its form is controlled by a conjugate chemical
potential distribution which plays the role of the requisite
interparticle interaction potential. Simulation approaches to the inverse
problem involve determining the form of for which
matches the available experimental data. The difficulty in
doing so is that is (in general) an unknown {\em functional} of
and must therefore be found by iteration. At high particle
densities and for high degrees of polydispersity, strong cross coupling between
and renders this process computationally
problematic and laborious. Here we describe an efficient and robust {\em
non-equilibrium} simulation scheme for finding the equilibrium form of
. The utility of the method is demonstrated by
calculating the chemical potential distribution conjugate to a specific
log-normal distribution of particle sizes in a polydisperse fluid.Comment: 6 pages, 3 figure
RFID Demystified: Part 3. Company Case Studies.
In the previous two parts of RFID Demystified we have discussed the technology, possible benefits and areas of application for with Radio Frequency Identification (RFID) systems. In this final part we review Company Case-Studies of those who have decided to apply the technology within their organisation. It will be seen that considerable benefits are being experienced within some organisations, pilot applications are increasing our learning and providing a foundation for the future success of projects in this area
Understanding collaborative supply chain relationships through the application of the Williamson organisational failure framework
Many researchers have studied supply chain relationships however, the
preponderance of open markets situations and ‘industry-style’ surveys have
reduced the empirical focus on the dynamics of long-term, collaborative dyadic
relationships. Within the supply chain the need for much closer, long-term
relationships is increasing due to supplier rationalisation and globalisation
(Spekman et al, 1998) and more information about these interactions is required.
The research specifically tested the well-accepted Williamson’s (1975) Economic
Organisations Failure Framework as a theoretical model through which long term
collaborative relationships can be
Polydispersity induced solid-solid transitions in model colloids
Specialized Monte Carlo simulation techniques and moment free energy method
calculations, capable of treating fractionation exactly, are deployed to study
the crystalline phase behaviour of an assembly of spherical particles described
by a top-hat "parent" distribution of particle sizes. An increase in either the
overall density or the degree of polydispersity is shown to generate a
succession of phase transitions in which the system demixes into an ever
greater number of face-centred cubic "daughter" phases. Each of these phases is
strongly fractionated: it contains a much narrower distribution of particle
sizes than is present in the system overall. Certain of the demixing
transitions are found to be nearly continuous, accompanied by fluctuations in
local particle size correlated over many lattice spacings. We explore possible
factors controlling the stability of the phases and the character of the
demixing transitions.Comment: 14 pages, 13 figure
Quantifying density fluctuations in water at a hydrophobic surface: evidence for critical drying
Employing smart Monte Carlo sampling techniques within the grand canonical
ensemble, we investigate the properties of water at a model hydrophobic
substrate. By reducing the strength of substrate-water attraction we find that
fluctuations in the local number density, quantified by a rigorous definition
of the local compressibility , increase rapidly for distances
within or molecular diameters from the substrate as the degree of
hydrophobicity, measured by the macroscopic contact angle , increases.
Our simulations provide evidence for a continuous (critical) drying transition
as the substrate-water interaction becomes very weak: . We
speculate that the existence of such a transition might account for earlier
simulation observations of strongly enhanced density fluctuations
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