418,219 research outputs found
Lattice Boltzmann modeling of multiphase flows at large density ratio with an improved pseudopotential model
Owing to its conceptual simplicity and computational efficiency, the
pseudopotential multiphase lattice Boltzmann (LB) model has attracted
significant attention since its emergence. In this work, we aim to extend the
pseudopotential LB model to simulate multiphase flows at large density ratio
and relatively high Reynolds number. First, based on our recent work [Li et
al., Phys. Rev. E. 86, 016709 (2012)], an improved forcing scheme is proposed
for the multiple-relaxation-time pseudopotential LB model in order to achieve
thermodynamic consistency and large density ratio in the model. Next, through
investigating the effects of the parameter a in the Carnahan-Starling equation
of state, we find that the interface thickness is approximately proportional to
1/sqrt(a). Using a smaller a will lead to a wider interface thickness, which
can reduce the spurious currents and enhance the numerical stability of the
pseudopotential model at large density ratio. Furthermore, it is found that a
lower liquid viscosity can be gained in the pseudopotential model by increasing
the kinematic viscosity ratio between the vapor and liquid phases. The improved
pseudopotential LB model is numerically validated via the simulations of
stationary droplet and droplet oscillation. Using the improved model as well as
the above treatments, numerical simulations of droplet splashing on a thin
liquid film are conducted at a density ratio in excess of 500 with Reynolds
numbers ranging from 40 to 1000. The dynamics of droplet splashing is correctly
reproduced and the predicted spread radius is found to obey the power law
reported in the literature.Comment: 9 figures, 2 tables, accepted by Physical Review E (in press
Nearly chirp- and pedestal-free pulse compression in nonlinear fiber Bragg gratings
Peer reviewedPublisher PD
Radio Frequency Identification: Supply Chain Impact and Implementation Challenges
Radio Frequency Identification (RFID) technology has received considerable attention from practitioners, driven by mandates from major retailers and the United States Department of Defense. RFID technology promises numerous benefits in the supply chain, such as increased visibility, security and efficiency. Despite such attentions and the anticipated benefits, RFID is not well-understood and many problems exist in the adoption and implementation of RFID. The purpose of this paper is to introduce RFID technology to practitioners and academicians by systematically reviewing the relevant literature, discussing how RFID systems work, their advantages, supply chain impacts, and the implementation challenges and the corresponding strategies, in the hope of providing guidance for practitioners in the implementation of RFID technology and offering a springboard for academicians to conduct future research in this area
Quantum correlations across two octaves from combined up and down conversion
We propose and analyse a cascaded optical parametric system which involves
three interacting modes across two octaves of frequency difference. Our system,
combining degenerate optical parametric oscillation (OPO) with second harmonic
generation (SHG), promises to be a useful source of squeezed and entangled
light at three differing frequencies. We show how changes in damping rates and
the ratio of the two concurrent nonlinearities affect the quantum correlations
in the output fields. We analyse the threshold behaviour, showing how the
normal OPO threshold is changed by the addition of the SHG interactions. We
also find that the inclusion of the OPO interaction removes the self-pulsing
behaviour found in normal SHG. Finally, we show how the Einstein-Podolsky-Rosen
correlations can be controlled by the injection of a coherent seed field at the
lower frequency.Comment: 23 pages, 11 figures, theor
On the foundations of cancer modelling: selected topics, speculations, & perspectives
This paper presents a critical review of selected topics related to the modelling of cancer onset, evolution and growth, with the aim of illustrating, to a wide applied mathematical readership, some of the novel mathematical problems in the field. This review attempts to capture, from the appropriate literature, the main issues involved in the modelling of phenomena related to cancer dynamics at all scales which characterise this highly complex system: from the molecular scale up to that of tissue. The last part of the paper discusses the challenge of developing a mathematical biological theory of tumour onset and evolution
Magnetic effects in heavy-ion collisions at intermediate energies
The time-evolution and space-distribution of internal electromagnetic fields
in heavy-ion reactions at beam energies between 200 and 2000 MeV/nucleon are
studied within an Isospin-dependent Boltzmann-Uhling-Uhlenbeck transport model
IBUU11. While the magnetic field can reach about G which is
significantly higher than the estimated surface magnetic field (
G) of magnetars, it has almost no effect on nucleon observables as the Lorentz
force is normally much weaker than the nuclear force. Very interestingly,
however, the magnetic field generated by the projectile-like (target-like)
spectator has a strong focusing/diverging effect on positive/negative pions at
forward (backward) rapidities. Consequently, the differential
ratio as a function of rapidity is significantly altered by the magnetic field
while the total multiplicities of both positive and negative pions remain about
the same. At beam energies above about 1 GeV/nucleon, while the integrated
ratio of total to multiplicities is not, the differential
ratio is sensitive to the density dependence of nuclear symmetry
energy . Our findings suggest that magnetic effects should
be carefully considered in future studies of using the differential
ratio as a probe of the at supra-saturation
densities.Comment: 12 pages including 8 figures and 1 tabl
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