4,023 research outputs found
Ultra-discrete Optimal Velocity Model: a Cellular-Automaton Model for Traffic Flow and Linear Instability of High-Flux Traffic
In this paper, we propose the ultra-discrete optimal velocity model, a
cellular-automaton model for traffic flow, by applying the ultra-discrete
method for the optimal velocity model. The optimal velocity model, defined by a
differential equation, is one of the most important models; in particular, it
successfully reproduces the instability of high-flux traffic. It is often
pointed out that there is a close relation between the optimal velocity model
and the mKdV equation, a soliton equation. Meanwhile, the ultra-discrete method
enables one to reduce soliton equations to cellular automata which inherit the
solitonic nature, such as an infinite number of conservation laws, and soliton
solutions. We find that the theory of soliton equations is available for
generic differential equations, and the simulation results reveal that the
model obtained reproduces both absolutely unstable and convectively unstable
flows as well as the optimal velocity model.Comment: 9 pages, 6 figure
Observation of Conduction Band Satellite of Ni Metal by 3p-3d Resonant Inverse Photoemission Study
Resonant inverse photoemission spectra of Ni metal have been obtained across
the Ni 3 absorption edge. The intensity of Ni 3 band just above Fermi
edge shows asymmetric Fano-like resonance. Satellite structures are found at
about 2.5 and 4.2 eV above Fermi edge, which show resonant enhancement at the
absorption edge. The satellite structures are due to a many-body configuration
interaction and confirms the existence of 3 configuration in the ground
state of Ni metal.Comment: 4 pages, 3 figures, submitted to Physical Review Letter
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
Entanglement of orbital angular momentum states between an ensemble of cold atoms and a photon
Recently, atomic ensemble and single photons were successfully entangled by
using collective enhancement [D. N. Matsukevich, \textit{et al.}, Phys. Rev.
Lett. \textbf{95}, 040405(2005).], where atomic internal states and photonic
polarization states were correlated in nonlocal manner. Here we experimentally
clarified that in an ensemble of atoms and a photon system, there also exists
an entanglement concerned with spatial degrees of freedom. Generation of
higher-dimensional entanglement between remote atomic ensemble and an
application to condensed matter physics are also discussed.Comment: 5 pages, 3 figure
Exact solution and asymptotic behaviour of the asymmetric simple exclusion process on a ring
In this paper, we study an exact solution of the asymmetric simple exclusion
process on a periodic lattice of finite sites with two typical updates, i.e.,
random and parallel. Then, we find that the explicit formulas for the partition
function and the average velocity are expressed by the Gauss hypergeometric
function. In order to obtain these results, we effectively exploit the
recursion formula for the partition function for the zero-range process. The
zero-range process corresponds to the asymmetric simple exclusion process if
one chooses the relevant hop rates of particles, and the recursion gives the
partition function, in principle, for any finite system size. Moreover, we
reveal the asymptotic behaviour of the average velocity in the thermodynamic
limit, expanding the formula as a series in system size.Comment: 10 page
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Predictions shape confidence in the right inferior frontal gyrus
It is clear that prior expectations shape perceptual decision-making, yet their contribution to the construction of subjective decision confidence remains largely unexplored. We recorded fMRI data while participants made perceptual decisions and confidence judgements, controlling for potential confounds of attention. We recorded fMRI data while participants made perceptual decisions accompanied by confidence judgements, controlling for potential confounds of attention. Results show that subjective confidence increases as perceptual prior expectations increasingly support the decision, and that this relationship is associated with BOLD activity in right inferior frontal gyrus (rIFG). Specifically, rIFG is sensitive to the discrepancy between expectation and decision (mismatch), and, crucially, higher mismatch responses are associated with lower decision confidence. Connectivity analyses revealed the source of the expectancy information to be bilateral orbitofrontal cortex (OFC) and the source of sensory signals to be intracalcarine sulcus. Altogether, our results indicate that predictive information is integrated into subjective confidence in rIFG, and reveal an occipital-frontal network that constructs confidence from top-down and bottom-up signals. This interpretation was further supported by exploratory findings that the white matter density of intracalcarine sulcus and OFC negatively predicted their respective contributions to the construction of confidence. Our findings advance our understanding of the neural basis of subjective perceptual processes by revealing an occipito-frontal functional network that integrates prior beliefs into the construction of confidence
High Precision CTE-Measurement of SiC-100 for Cryogenic Space-Telescopes
We present the results of high precision measurements of the thermal
expansion of the sintered SiC, SiC-100, intended for use in cryogenic
space-telescopes, in which minimization of thermal deformation of the mirror is
critical and precise information of the thermal expansion is needed for the
telescope design. The temperature range of the measurements extends from room
temperature down to 10 K. Three samples, #1, #2, and #3 were
manufactured from blocks of SiC produced in different lots. The thermal
expansion of the samples was measured with a cryogenic dilatometer, consisting
of a laser interferometer, a cryostat, and a mechanical cooler. The typical
thermal expansion curve is presented using the 8th order polynomial of the
temperature. For the three samples, the coefficients of thermal expansion
(CTE), \bar{\alpha}_{#1}, \bar{\alpha}_{#2}, and \bar{\alpha}_{#3} were
derived for temperatures between 293 K and 10 K. The average and the dispersion
(1 rms) of these three CTEs are 0.816 and 0.002 (/K),
respectively. No significant difference was detected in the CTE of the three
samples from the different lots. Neither inhomogeneity nor anisotropy of the
CTE was observed. Based on the obtained CTE dispersion, we performed an
finite-element-method (FEM) analysis of the thermal deformation of a 3.5 m
diameter cryogenic mirror made of six SiC-100 segments. It was shown that the
present CTE measurement has a sufficient accuracy well enough for the design of
the 3.5 m cryogenic infrared telescope mission, the Space Infrared telescope
for Cosmology and Astrophysics (SPICA).Comment: in press, PASP. 21 pages, 4 figure
Measurement and control systems for an imaging electromagnetic flow meter
Electromagnetic flow metres based on the principles of Faraday's laws of induction have been used successfully in many industries. The conventional electromagnetic flow metre can measure the mean liquid velocity in axisymmetric single phase flows. However, in order to achieve velocity profile measurements in single phase flows with non-uniform velocity profiles, a novel imaging electromagnetic flow metre (IEF) has been developed which is described in this paper. The novel electromagnetic flow metre which is based on the ‘weight value’ theory to reconstruct velocity profiles is interfaced with a ‘Microrobotics VM1’ microcontroller as a stand-alone unit. The work undertaken in the paper demonstrates that an imaging electromagnetic flow metre for liquid velocity profile measurement is an instrument that is highly suited for control via a microcontroller
Study of Neutron-Rich N = 50 Nuclei
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