224,605 research outputs found
Origin of synchronized traffic flow on highways and its dynamic phase transitions
We study the traffic flow on a highway with ramps through numerical
simulations of a hydrodynamic traffic flow model. It is found that the presence
of the external vehicle flux through ramps generates a new state of recurring
humps (RH). This novel dynamic state is characterized by temporal oscillations
of the vehicle density and velocity which are localized near ramps, and found
to be the origin of the synchronized traffic flow reported recently [PRL 79,
4030 (1997)]. We also argue that the dynamic phase transitions between the free
flow and the RH state can be interpreted as a subcritical Hopf bifurcation.Comment: 4 pages, source TeX file and 4 figures are tarred and compressed via
uufile
Ignition means for monopropellant Patent
Catalyst bed ignition system for hydrazine propellant
Evaluation of Skylab S190-A photos for rock discrimination and comparison with ERTS imagery
There are no author-identified significant results in this report
Renormalization Group Study of the Electron-phonon Interaction in the High Tc Cuprates
We generalize the numerical renormalization group scheme to study the
phonon-mediated retarded interactions in the high Tc cuprates. We find that
three sets of phonon-mediated retarded quasiparticle scatterings grow under RG
flow. These scatterings share the following common features: 1) the initial and
final quasiparticle momenta are in the antinodal regions, and 2) the scattering
amplitudes have a symmetry. All three sets of retarded interaction
are driven to strong coupling by the magnetic fluctuations around .
After growing strong, these retarded interaction will trigger density wave
orders with d-wave symmetry. However, due to the d-wave form factor they will
leave the nodal quasiparticle unaffected. We conclude that the main effect of
electron-phonon coupling in the cuprates is to promote these density wave
orders.Comment: 4 pages, 3 figures, references added, added more details about
others' previous studie
Critical Conductance and Its Fluctuations at Integer Hall Plateau Transitions
Under periodic boundary condition in the transverse direction, we calculate
the averaged zero-temperature two-terminal conductance ( for ) at the critical point of
integer quantum Hall plateau transitions. We find {\it universal} values for
, and ,
where ; ; ; and
respectively. We also determine the leading finite size
scaling corrections to these observables. Comparisons with experiments will be
made.Comment: 13 pages, 3 Postscript figures included, Final version with minor
corrections, To appear in Physical Review Letter
Neutron Electric Dipole Moment at Fixed Topology
We describe the finite volume effects of CP-odd quantities, such as the
neutron electric dipole moment and the anapole moment in the -vacuum,
under different topological sectors. We evaluate the three-point Green's
functions for the electromagnetic current in a fixed non-trivial topological
sector in order to extract these CP-odd observables. We discuss the role of
zero modes in the CP-odd Green's function and show that, in the quenched
approximation, there is a power divergence in the quark mass for CP-odd
quantities at finite volume.Comment: 12 pages, revised manuscript to be publishe
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