217 research outputs found
The effect of detachment and attachment to a kink motion in the asymmetric simple exclusion process
We study the dynamics of a kink in a one-lane asymmetric simple exclusion
process with detachment and attachment of the particle at arbitrary sites. For
a system with one site of detachment and attachment we find that the kink is
trapped by the site, and the probability distribution of the kink position is
described by the overdumped Fokker-Planck equation with a V-shaped potential.
Our results can be applied to the motion of a kink in arbitrary number of sites
where detachment and attachment take place. When detachment and attachment take
place at every site, we confirm that the kink motion obeys the diffusion in a
harmonic potential. We compare our results with the Monte Carlo simulation, and
check the quantitative validity of our theoretical prediction of the diffusion
constant and the potential form.Comment: 10 pages, 5 figure
Fabrication of Unglazed Ceramic Tile Using Dense Structured Sago Waste and Clay Composite
In Indonesia, the sago processing industry generates every year huge amount of sago waste, and converting this waste into a useful material is possible. In the present study, physical properties of dense structured sago waste and clay composite were investigated in order to study the feasibility of reuse this sample as raw material in the producing of ceramics. Firstly, the chemical composition of ash (obtained from the sago waste) and clay was characterized. The prepared sample was sintered at the temperature range from 800 to 1,200 °C using electric furnace. The density, linear shrinkage and water absorption of the sintered sample were determined by using the Archimedes' method. The experimental result indicated that the density of the sintered sample increased with increasing sintering temperature up to 1100 °C and then slightly decreased afterward. The water absorption of the products decreased with an increase in sintering temperature. In the sintered sample at 1,100 °C, the water absorption decreased rapidly and water adsorption of less than 1%was achieved. This water absorption was less than 5% which was needed for unglazed floor tile. The result of water adsorption suggest that it is possible to use this sample as a raw material for producing the ceramic floor tile
Parallel Coupling of Symmetric and Asymmetric Exclusion Processes
A system consisting of two parallel coupled channels where particles in one
of them follow the rules of totally asymmetric exclusion processes (TASEP) and
in another one move as in symmetric simple exclusion processes (SSEP) is
investigated theoretically. Particles interact with each other via hard-core
exclusion potential, and in the asymmetric channel they can only hop in one
direction, while on the symmetric lattice particles jump in both directions
with equal probabilities. Inter-channel transitions are also allowed at every
site of both lattices. Stationary state properties of the system are solved
exactly in the limit of strong couplings between the channels. It is shown that
strong symmetric couplings between totally asymmetric and symmetric channels
lead to an effective partially asymmetric simple exclusion process (PASEP) and
properties of both channels become almost identical. However, strong asymmetric
couplings between symmetric and asymmetric channels yield an effective TASEP
with nonzero particle flux in the asymmetric channel and zero flux on the
symmetric lattice. For intermediate strength of couplings between the lattices
a vertical cluster mean-field method is developed. This approximate approach
treats exactly particle dynamics during the vertical transitions between the
channels and it neglects the correlations along the channels. Our calculations
show that in all cases there are three stationary phases defined by particle
dynamics at entrances, at exits or in the bulk of the system, while phase
boundaries depend on the strength and symmetry of couplings between the
channels. Extensive Monte Carlo computer simulations strongly support our
theoretical predictions.Comment: 16 page
Inhomogeneous Coupling in Two-Channel Asymmetric Simple Exclusion Processes
Asymmetric exclusion processes for particles moving on parallel channels with
inhomogeneous coupling are investigated theoretically. Particles interact with
hard-core exclusion and move in the same direction on both lattices, while
transitions between the channels is allowed at one specific location in the
bulk of the system. An approximate theoretical approach that describes the
dynamics in the vertical link and horizontal lattice segments exactly but
neglects the correlation between the horizontal and vertical transport is
developed. It allows us to calculate stationary phase diagrams, particle
currents and densities for symmetric and asymmetric transitions between the
channels. It is shown that in the case of the symmetric coupling there are
three stationary phases, similarly to the case of single-channel totally
asymmetric exclusion processes with local inhomogeneity. However, the
asymmetric coupling between the lattices lead to a very complex phase diagram
with ten stationary-state regimes. Extensive Monte Carlo computer simulations
generally support theoretical predictions, although simulated stationary-state
properties slightly deviate from calculated in the mean-field approximation,
suggesting the importance of correlations in the system. Dynamic properties and
phase diagrams are discussed by analyzing constraints on the particle currents
across the channels
Traffic jams induced by rare switching events in two-lane transport
We investigate a model for driven exclusion processes where internal states are assigned to the particles. The latter account for diverse situations, ranging from spin states in spintronics to parallel lanes in intracellular or vehicular traffic. Introducing a coupling between the internal states by allowing particles to switch from one to another induces an intriguing polarization phenomenon. In a mesoscopic scaling, a rich stationary regime for the density profiles is discovered, with localized domain walls in the density profile of one of the internal states being feasible. We derive the shape of the density profiles as well as resulting phase diagrams analytically by a mean-field approximation and a continuum limit. Continuous as well as discontinuous lines of phase transition emerge, their intersections induce multi-critical behaviour
Dynamics at barriers in bidirectional two-lane exclusion processes
A two-lane exclusion process is studied where particles move in the two lanes
in opposite directions and are able to change lanes. The focus is on the steady
state behavior in situations where a positive current is constrained to an
extended subsystem (either by appropriate boundary conditions or by the
embedding environment) where, in the absence of the constraint, the current
would be negative. We have found two qualitatively different types of steady
states and formulated the conditions of them in terms of the transition rates.
In the first type of steady state, a localized cluster of particles forms with
an anti-shock located in the subsystem and the current vanishes exponentially
with the extension of the subsystem. This behavior is analogous to that of the
one-lane partially asymmetric simple exclusion process, and can be realized
e.g. when the local drive is induced by making the jump rates in two lanes
unequal. In the second type of steady state, which is realized e.g. if the
local drive is induced purely by the bias in the lane change rates, and which
has thus no counterpart in the one-lane model, a delocalized cluster of
particles forms which performs a diffusive motion as a whole and, as a
consequence, the current vanishes inversely proportionally to the extension of
the subsystem. The model is also studied in the presence of quenched
disordered, where, in case of delocalization, phenomenological considerations
predict anomalously slow, logarithmic decay of the current with the system size
in contrast with the usual power-law.Comment: 24 pages, 13 figure
Spontaneous Symmetry Breaking in Two-Channel Asymmetric Exclusion Processes with Narrow Entrances
Multi-particle non-equilibrium dynamics in two-channel asymmetric exclusion
processes with narrow entrances is investigated theoretically. Particles move
on two parallel lattices in opposite directions without changing them, while
the channels are coupled only at the boundaries. A particle cannot enter the
corresponding lane if the exit site of the other lane is occupied. Stationary
phase diagrams, particle currents and densities are calculated in a mean-field
approximation. It is shown that there are four stationary phases in the system,
with two of them exhibiting spontaneous symmetry breaking phenomena. Extensive
Monte Carlo computer simulations confirm qualitatively our predictions,
although the phase boundaries and stationary properties deviate from the
mean-field results. Computer simulations indicate that several dynamic and
phase properties of the system have a strong size dependency, and one of the
stationary phases predicted by the mean-field theory disappears in the
thermodynamic limit.Comment: 13 page
High field magnetic resonant properties of beta'-(ET)2SF5CF2SO3
A systematic electron spin resonance (ESR) investigation of the low
temperature regime for the (ET)2SF5CF2SO3 system was performed in the frequency
range of ~200-700 GHz, using backward wave oscillator sources, and at fields up
to 25 T. Newly acquired access to the high frequency and fields shows
experimental ESR results in agreement with the nuclear magnetic resonance (NMR)
investigation, revealing evidence that the transition seen at 20 K is not of
conventional spin-Peierls order. A significant change of the spin resonance
spectrum in beta'-(ET)2SF5CF2SO3 at low temperatures, indicates a transition
into a three-dimensional-antiferromagnetic (3D AFM) phase.Comment: 4 pages, 7 figures, minor grammatical change
- …