1,936 research outputs found
Solvable Optimal Velocity Models and Asymptotic Trajectory
In the Optimal Velocity Model proposed as a new version of Car Following
Model, it has been found that a congested flow is generated spontaneously from
a homogeneous flow for a certain range of the traffic density. A
well-established congested flow obtained in a numerical simulation shows a
remarkable repetitive property such that the velocity of a vehicle evolves
exactly in the same way as that of its preceding one except a time delay .
This leads to a global pattern formation in time development of vehicles'
motion, and gives rise to a closed trajectory on -
(headway-velocity) plane connecting congested and free flow points. To obtain
the closed trajectory analytically, we propose a new approach to the pattern
formation, which makes it possible to reduce the coupled car following
equations to a single difference-differential equation (Rondo equation). To
demonstrate our approach, we employ a class of linear models which are exactly
solvable. We also introduce the concept of ``asymptotic trajectory'' to
determine and (the backward velocity of the pattern), the global
parameters associated with vehicles' collective motion in a congested flow, in
terms of parameters such as the sensitivity , which appeared in the original
coupled equations.Comment: 25 pages, 15 eps figures, LaTe
Dynamical Gauge Boson and Strong-Weak Reciprocity
It is proposed that asymptotically nonfree gauge theories are consistently
interpreted as theories of composite gauge bosons. It is argued that when
hidden local symmetry is introduced, masslessness and coupling universality of
dynamically generated gauge boson are ensured. To illustrate these ideas we
take a four dimensional Grassmannian sigma model as an example and show that
the model should be regarded as a cut-off theory and there is a critical
coupling at which the hidden local symmetry is restored. Propagator and vertex
functions of the gauge field are calculated explicitly and existence of the
massless pole is shown. The beta function determined from the factor of
the dynamically generated gauge boson coincides with that of an asymptotic
nonfree elementary gauge theory. Using these theoretical machinery we construct
a model in which asymptotic free and nonfree gauge bosons coexist and their
running couplings are related by the reciprocally proportional relation.Comment: 19 pages, latex, 6 eps figures, a numbers of corrections are made in
the tex
Line bundles in supersymmetric coset models
The scalars of an N = 1 supersymmetric sigma-model in 4 dimensions
parameterize a Kaehler manifold. The transformations of their fermionic
superpartners under the isometries are often anomalous. These anomalies can be
canceled by introducing additional chiral multiplets with appropriate charges.
To obtain the right charges a non-trivial singlet compensating multiplet can be
used. However when the topology of the underlying Kaehler manifold is
non-trivial, the consistency of this multiplet requires that its charge is
quantized. This singlet can be interpreted as a section of a line bundle. We
determine the Kaehler potentials corresponding to the minimal non-trivial
singlet chiral superfields for any compact Kaehlerian coset space G/H. The
quantization condition may be in conflict with the requirement of anomaly
cancelation. To illustrate this, we discuss the consistency of anomaly free
models based on the coset spaces E_6/SO(10)xU(1) and SU(5)/SU(2)xU(1)xSU(3).Comment: 10 pages, LaTeX, no figure
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
Presence of Many Stable Nonhomogeneous States in an Inertial Car-Following Model
A new single lane car following model of traffic flow is presented. The model
is inertial and free of collisions. It demonstrates experimentally observed
features of traffic flow such as the existence of three regimes: free,
fluctuative (synchronized) and congested (jammed) flow; bistability of free and
fluctuative states in a certain range of densities, which causes the hysteresis
in transitions between these states; jumps in the density-flux plane in the
fluctuative regime and gradual spatial transition from synchronized to free
flow. Our model suggests that in the fluctuative regime there exist many stable
states with different wavelengths, and that the velocity fluctuations in the
congested flow regime decay approximately according to a power law in time.Comment: 4 pages, 4 figure
Proving the Low Energy Theorem of Hidden Local Symmetry
Based on the Ward-Takahashi identity for the BRS symmetry, we prove to all
orders of the loop expansion the low energy theorem of hidden local symmetry
for the vector mesons (KSRF (I) relation) in the
/ nonlinear chiral Lagrangian.Comment: 12 pages, LaTeX, DPNU-93-01/KUNS-117
Playing with fermion couplings in Higgsless models
We discuss the fermion couplings in a four dimensional SU(2) linear moose
model by allowing for direct couplings between the left-handed fermions on the
boundary and the gauge fields in the internal sites. This is realized by means
of a product of non linear -model scalar fields which, in the continuum
limit, is equivalent to a Wilson line. The effect of these new non local
couplings is a contribution to the parameter which can be of
opposite sign with respect to the one coming from the gauge fields along the
string. Therefore, with some fine tuning, it is possible to satisfy the
constraints from the electroweak data.Comment: Latex file, 20 pages, 4 eps figure
Stability Analysis of Optimal Velocity Model for Traffic and Granular Flow under Open Boundary Condition
We analyzed the stability of the uniform flow solution in the optimal
velocity model for traffic and granular flow under the open boundary condition.
It was demonstrated that, even within the linearly unstable region, there is a
parameter region where the uniform solution is stable against a localized
perturbation. We also found an oscillatory solution in the linearly unstable
region and its period is not commensurate with the periodicity of the car index
space. The oscillatory solution has some features in common with the
synchronized flow observed in real traffic.Comment: 4 pages, 6 figures. Typos removed. To appear in J. Phys. Soc. Jp
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