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

An application of cluster detection to scene analysis

Certain arrangements of local features in a scene tend to group together and to be seen as units. It is suggested that in some instances, this phenomenon might be interpretable as a process of cluster detection in a graph-structured space derived from the scene. This idea is illustrated using a class of scenes that contain only horizontal and vertical line segments

Duality relation for frustrated spin models

We consider discrete spin models on arbitrary planar graphs and lattices with frustrated interactions. We first analyze the Ising model with frustrated plaquettes. We use an algebraic approach to derive the result that an Ising model with some of its plaquettes frustrated has a dual which is an Ising model with an external field $i\pi/2$ applied to the dual sites centered at frustrated plaquettes. In the case that all plaquettes are frustrated, this leads to the known result that the dual model has a uniform field $i\pi/2$ whose partition function can be evaluated in the thermodynamic limit for regular lattices. The analysis is extended to a Potts spin glass with analogous results obtained.Comment: Several relevant references are added. Comments on their relation to this work are also adde

Gauge bosons and the AdS_3/LCFT_2 correspondence

We study the relationship between the gauge boson coupled to spin 2 operator and the singleton in three-dimensional anti-de Sitter space(AdS$_3$). The singleton can be expressed in terms of a pair of dipole ghost fields $A$ and $B$ which couple to $D$ and $C$ operators on the boundary of AdS$_3$. These operators form the logarithmic conformal field theory(LCFT$_2$). Using the correlation function for logarithmic pair, we calculate the greybody factor for the singleton. In the low temperature limit of $\omega \gg T_{\pm}$, this is compared with the result of the bulk AdS$_3$ calculation of the gauge boson. We find that the gauge boson cannot be realized as a model of the AdS$_3$/LCFT$_2$ correspondence.Comment: 9 pages, no figures, previous version should be replaced with this, the result was reverse

Thermal Model and Optimization of a Large Crystal Detector using a Metallic Magnetic Calorimeter

We established a simple thermal model of the heat flow in a large crystal detector designed for a neutrinoless double beta decay experiment. The detector is composed of a CaMoO$_{4}$ crystal and a metallic magnetic calorimeter (MMC). The thermal connection between the absorber and the sensor consists of a gold film evaporated on the crystal surface and gold bonding wires attached to this film and the MMC sensor. The model describes athermal and thermal processes of heat flow to the gold film. A successive experiment based on optimization calculations of the area and thickness of the gold film showed a significant improvement in the size and rise-time of the measured signals

Time-Dependent Variational Approach to the Non-Abelian Pure Gauge Theory

The time-dependent variational approach to the pure Yang-Mills gauge theory, especially a color su(3) gauge theory, is formulated in the functional Schroedinger picture with a Gaussian wave functional approximation. The equations of motion for the quantum gauge fields are formulated in the Liouville-von Neumann form. This variational approach is applied in order to derive the transport coefficients, such as the shear viscosity, for the pure gluonic matter by using the linear response theory. As a result, the contribution to the shear viscosity from the quantum gluons is zero up to the lowest order of the coupling g in the quantum gluonic matter.Comment: 19 pages, no figures, using PTPTeX.cl