257 research outputs found
Two-dimensional cellular automaton model of traffic flow with open boundaries
A two-dimensional cellular automaton model of traffic flow with open
boundaries are investigated by computer simulations. The outflow of cars from
the system and the average velocity are investigated. The time sequences of the
outflow and average velocity have flicker noises in a jamming phase. The low
density behavior are discussed with simple jam-free approximation.Comment: 14 pages, Phys. Rev. E in press, PostScript figures available at
ftp://hirose.ai.is.saga-u.ac.jp/pub/documents/papers/1996/2DTR/
OpenBoundaries/Figs.tar.g
Phase Diagram Of The Biham-Middleton-Levine Traffic Model In Three Dimensions
We study numerically the behavior of the Biham-Middleton-Levine traffic model
in three dimensions. Our extensive numerical simulations show that the phase
diagram for this model in three dimensions is markedly different from that in
one and two dimensions. In addition to the full speed moving as well as the
completely jamming phases, whose respective average asymptotic car speeds
equal one and zero, we observe an extensive region of car densities with
a low but non-zero average asymptotic car speed. The transition from this
extensive low average asymptotic car speed region to the completely jamming
region is at least second order. We argue that this low speed region is a
result of the formation of a spatially-limited-extended percolating cluster.
Thus, this low speed phase is present in dimensional
Biham-Middleton-Levine model as well.Comment: Minor clarifications, 1 figure adde
Energy Dissipation Burst on the Traffic Congestion
We introduce an energy dissipation model for traffic flow based on the
optimal velocity model (OV model). In this model, vehicles are defined as
moving under the rule of the OV model, and energy dissipation rate is defined
as the product of the velocity of a vehicle and resistant force which works to
it.Comment: 15 pages, 19 Postscript figures. Reason for replacing: This is the
submitted for
SXDF-UDS-CANDELS-ALMA 1.5 arcmin deep survey
We have conducted 1.1 mm ALMA observations of a contiguous or 1.5 arcmin window in the SXDF-UDS-CANDELS. We achieved a 5
sensitivity of 0.28 mJy, providing a flat sensus of dusty star-forming galaxies
with (for =40K) up to
thanks to the negative K-correction at this wavelength. We detected 5
brightest sources (S/N6) and 18 low-significance sources (5S/N4; these
may contain spurious detections, though). One of the 5 brightest ALMA sources
( mJy) is extremely faint in the WFC3 and
VLT/HAWK-I images, demonstrating that a contiguous ALMA imaging survey is able
to uncover a faint dust-obscured population that is invisible in deep
optical/near-infrared surveys. We found a possible [CII]-line emitter at
or a low- CO emitting galaxy within the field, which may allow us
to constrain the [CII] and/or the CO luminosity functions across the history of
the universe.Comment: 4 pages, 2 figures, 1 table, to appear in the proceedings of IAU
Symposium 319 "Galaxies at High Redshift and Their Evolution over Cosmic
Time", eds. S. Kaviraj & H. Ferguso
Calibration of the Particle Density in Cellular-Automaton Models for Traffic Flow
We introduce density dependence of the cell size in cellular-automaton models
for traffic flow, which allows a more precise correspondence between real-world
phenomena and what observed in simulation. Also, we give an explicit
calibration of the particle density particularly for the asymmetric simple
exclusion process with some update rules. We thus find that the present method
is valid in that it reproduces a realistic flow-density diagram.Comment: 2 pages, 2 figure
Macroscopic traffic models from microscopic car-following models
We present a method to derive macroscopic fluid-dynamic models from
microscopic car-following models via a coarse-graining procedure. The method is
first demonstrated for the optimal velocity model. The derived macroscopic
model consists of a conservation equation and a momentum equation, and the
latter contains a relaxation term, an anticipation term, and a diffusion term.
Properties of the resulting macroscopic model are compared with those of the
optimal velocity model through numerical simulations, and reasonable agreement
is found although there are deviations in the quantitative level. The
derivation is also extended to general car-following models.Comment: 12 pages, 4 figures; to appear in Phys. Rev.
ALMA twenty-six arcmin2 survey of GOODS-S at one millimeter (ASAGAO): Millimeter properties of stellar mass selected galaxies
We make use of the ASAGAO, deep 1.2 mm continuum observations of a 26
arcmin region in the GOODS-South field obtained with ALMA, to probe
dust-enshrouded star formation in -band selected (i.e., stellar mass
selected) galaxies, which are drawn from the ZFOURGE catalog. Based on the
ASAGAO combined map, which was created by combining ASAGAO and ALMA archival
data in the GOODS-South field, we find that 24 ZFOURGE sources have 1.2 mm
counterparts with a signal-to-noise ratio 4.5 (1 30 - 70
Jy beam at 1.2 mm). Their median redshift is estimated to be
2.38 0.14. They generally follow the tight
relationship of the stellar mass versus star formation rate (i.e., the main
sequence of star-forming galaxies). ALMA-detected ZFOURGE sources exhibit
systematically larger infrared (IR) excess (IRX ) compared to ZFOURGE galaxies without ALMA
detections even though they have similar redshifts, stellar masses, and star
formation rates. This implies the consensus stellar-mass versus IRX relation,
which is known to be tight among rest-frame-UV-selected galaxies, can not fully
predict the ALMA detectability of stellar-mass-selected galaxies. We find that
ALMA-detected ZFOURGE sources are the main contributors to the cosmic IR star
formation rate density at = 2 - 3.Comment: Accepted for publication in PASJ. A version with a high resolution
figure and ALMA fits files are available from
https://sites.google.com/view/asagao26
Initial Results from the Nobeyama Molecular Gas Observations of Distant Bright Galaxies
We present initial results from the CO survey toward high redshift galaxies
using the Nobeyama 45m telescope. Using the new wide bandwidth spectrometer
equipped with a two-beam SIS receiver, we have robust new detections of three
high redshift (z=1.6-3.4) submillimeter galaxies (SXDF 1100.001, SDP9, and
SDP17), one tentative detection (SDSS J160705+533558), and one non-detection
(COSMOS-AzTEC1). The galaxies observed during the commissioning phase are
sources with known spectroscopic redshifts from previous optical or from
wide-band submm spectroscopy. The derived molecular gas mass and line widths
from Gaussian fits are ~10^11 Msun and 430-530 km/s, which are consistent with
previous CO observations of distant submm galaxies and quasars. The
spectrometer that allows a maximum of 32 GHz instantaneous bandwidth will
provide new science capabilities at the Nobeyama 45m telescope, allowing us to
determine redshifts of bright submm selected galaxies without any prior
redshift information.Comment: 4 pages, 1 figure, PASJ Letter Accepte
Concept of temperature in multi-horizon spacetimes: Analysis of Schwarzschild-De Sitter metric
In case of spacetimes with single horizon, there exist several
well-established procedures for relating the surface gravity of the horizon to
a thermodynamic temperature. Such procedures, however, cannot be extended in a
straightforward manner when a spacetime has multiple horizons. In particular,
it is not clear whether there exists a notion of global temperature
characterizing the multi-horizon spacetimes. We examine the conditions under
which a global temperature can exist for a spacetime with two horizons using
the example of Schwarzschild-De Sitter (SDS) spacetime. We systematically
extend different procedures (like the expectation value of stress tensor,
response of particle detectors, periodicity in the Euclidean time etc.) for
identifying a temperature in the case of spacetimes with single horizon to the
SDS spacetime. This analysis is facilitated by using a global coordinate chart
which covers the entire SDS manifold. We find that all the procedures lead to a
consistent picture characterized by the following features: (a) In general, SDS
spacetime behaves like a non-equilibrium system characterized by two
temperatures. (b) It is not possible to associate a global temperature with SDS
spacetime except when the ratio of the two surface gravities is rational (c)
Even when the ratio of the two surface gravities is rational, the thermal
nature depends on the coordinate chart used. There exists a global coordinate
chart in which there is global equilibrium temperature while there exist other
charts in which SDS behaves as though it has two different temperatures. The
coordinate dependence of the thermal nature is reminiscent of the flat
spacetime in Minkowski and Rindler coordinate charts. The implications are
discussed.Comment: 12 page
Experimental study of pedestrian flow through a bottleneck
In this work the results of a bottleneck experiment with pedestrians are
presented in the form of total times, fluxes, specific fluxes, and time gaps. A
main aim was to find the dependence of these values from the bottleneck width.
The results show a linear decline of the specific flux with increasing width as
long as only one person at a time can pass, and a constant value for larger
bottleneck widths. Differences between small (one person at a time) and wide
bottlenecks (two persons at a time) were also found in the distribution of time
gaps.Comment: accepted for publication in J. Stat. Mec
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