1,300 research outputs found
Experiences with a simplified microsimulation for the Dallas/Fort Worth area
We describe a simple framework for micro simulation of city traffic. A medium
sized excerpt of Dallas was used to examine different levels of simulation
fidelity of a cellular automaton method for the traffic flow simulation and a
simple intersection model. We point out problems arising with the granular
structure of the underlying rules of motion.Comment: accepted by Int.J.Mod.Phys.C, 20 pages, 14 figure
Automated determination of hydrogen cyanide acrolein and total aldehydes in the gas phase of tobacco smoke
A Cellular Automaton Model for Bi-Directionnal Traffic
We investigate a cellular automaton (CA) model of traffic on a bi-directional
two-lane road. Our model is an extension of the one-lane CA model of {Nagel and
Schreckenberg 1992}, modified to account for interactions mediated by passing,
and for a distribution of vehicle speeds. We chose values for the various
parameters to approximate the behavior of real traffic. The density-flow
diagram for the bi-directional model is compared to that of a one-lane model,
showing the interaction of the two lanes. Results were also compared to
experimental data, showing close agreement. This model helps bridge the gap
between simplified cellular automata models and the complexity of real-world
traffic.Comment: 4 pages 6 figures. Accepted Phys Rev
A Simplified Cellular Automaton Model for City Traffic
We systematically investigate the effect of blockage sites in a cellular
automaton model for traffic flow. Different scheduling schemes for the blockage
sites are considered. None of them returns a linear relationship between the
fraction of ``green'' time and the throughput. We use this information for a
fast implementation of traffic in Dallas.Comment: 12 pages, 18 figures. submitted to Phys Rev
Bulk and Surface Nucleation Processes in Ag2S Conductance Switches
We studied metallic Ag formation inside and on the surface of Ag2S thin
films, induced by the electric field created with a STM tip. Two clear regimes
were observed: cluster formation on the surface at low bias voltages, and full
conductance switching at higher bias voltages (V > 70mV). The bias voltage at
which this transition is observed is in agreement with the known threshold
voltage for conductance switching at room temperature. We propose a model for
the cluster formation at low bias voltage. Scaling of the measured data with
the proposed model indicates that the process takes place near steady state,
but depends on the STM tip geometry. The growth of the clusters is confirmed by
tip retraction measurements and topography scans. This study provides improved
understanding of the physical mechanisms that drive conductance switching in
solid electrolyte memristive devices.Comment: In press for PR
Fuzzy cellular model for on-line traffic simulation
This paper introduces a fuzzy cellular model of road traffic that was
intended for on-line applications in traffic control. The presented model uses
fuzzy sets theory to deal with uncertainty of both input data and simulation
results. Vehicles are modelled individually, thus various classes of them can
be taken into consideration. In the proposed approach, all parameters of
vehicles are described by means of fuzzy numbers. The model was implemented in
a simulation of vehicles queue discharge process. Changes of the queue length
were analysed in this experiment and compared to the results of NaSch cellular
automata model.Comment: The original publication is available at http://www.springerlink.co
Slow, Steady-State Transport with "Loading" and Bulk Reactions: the Mixed Ionic Conductor LaCuO
We consider slow, steady transport for the normal state of the superconductor
LaCuO in a one-dimensional geometry, with surface fluxes
sufficiently general to permit oxygen to be driven into the sample (``loaded'')
either by electrochemical means or by high oxygen partial pressure. We include
the bulk reaction OO, where neutral atoms () go into ions
() and holes (). For slow, steady transport, the transport equations
simplify because the bulk reaction rate density and the bulk loading rates
then are uniform in space and time. All three fluxes must be
specified at each surface, which for a uniform current density corresponds
to five independent fluxes. These fluxes generate two types of static modes at
each surface and a bulk response with a voltage profile that varies
quadratically in space, characterized by and the total oxygen flux
(neutral plus ion) at each surface. One type of surface mode is associated with
electrical screening; the other type is associated both with diffusion and
drift, and with chemical reaction (the {\it diffusion-reaction mode}). The
diffusion-reaction mode is accompanied by changes in the chemical potentials
, and by reactions and fluxes, but it neither carries current (J=0) nor
loads the system chemically (). Generation of the diffusion-reaction
mode may explain the phenomenon of ``turbulence in the voltage'' often observed
near the electrodes of other mixed ionic electronic conductors (MIECs).Comment: 11 pages, 1 figur
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