36,144 research outputs found
Connecting the Micro-dynamics to the Emergent Macro-variables: Self-Organized Criticality and Absorbing Phase Transitions in the Deterministic Lattice Gas
We reinvestigate the Deterministic Lattice Gas introduced as a paradigmatic
model of the 1/f spectra (Phys. Rev. Lett. V26, 3103 (1990)) arising according
to the Self-Organized Criticality scenario. We demonstrate that the density
fluctuations exhibit an unexpected dependence on systems size and relate the
finding to effective Langevin equations. The low density behavior is controlled
by the critical properties of the gas at the absorbing state phase transition.
We also show that the Deterministic Lattice Gas is in the Manna universality
class of absorbing state phase transitions. This is in contrast to expectations
in the literature which suggested that the entirely deterministic nature of the
dynamics would put the model in a different universality class. To our
knowledge this is the first fully deterministic member of the Manna
universality class.Comment: 8 pages, 12 figures. Changes in the new version: Reference list has
been correcte
Evaluation of initial collector field performance at the Langley Solar Building Test Facility
The thermal performance of the solar collector field for the NASA Langley Solar Building Test Facility is given for October 1976 through January 1977. A 1,180 square meter solar collector field with seven collector designs helped to provide hot water for the building heating system and absorption air conditioner. The collectors were arranged in 12 rows with nominally 51 collectors per row. Heat transfer rates for each row were calculated and recorded along with sensor, insolation, and weather data every five minutes using a minicomputer. The agreement between the experimental and predicted collector efficiencies was generally within five percentage points
Synchronization Model for Stock Market Asymmetry
The waiting time needed for a stock market index to undergo a given
percentage change in its value is found to have an up-down asymmetry, which,
surprisingly, is not observed for the individual stocks composing that index.
To explain this, we introduce a market model consisting of randomly fluctuating
stocks that occasionally synchronize their short term draw-downs. These
synchronous events are parameterized by a ``fear factor'', that reflects the
occurrence of dramatic external events which affect the financial market.Comment: 4 pages, 4 figure
Reentrant phase diagram of branching annihilating random walks with one and two offsprings
We investigate the phase diagram of branching annihilating random walks with
one and two offsprings in one dimension. A walker can hop to a nearest neighbor
site or branch with one or two offsprings with relative ratio. Two walkers
annihilate immediately when they meet. In general, this model exhibits a
continuous phase transition from an active state into the absorbing state
(vacuum) at a finite hopping probability. We map out the phase diagram by Monte
Carlo simulations which shows a reentrant phase transition from vacuum to an
active state and finally into vacuum again as the relative rate of the
two-offspring branching process increases. This reentrant property apparently
contradicts the conventional wisdom that increasing the number of offsprings
will tend to make the system more active. We show that the reentrant property
is due to the static reflection symmetry of two-offspring branching processes
and the conventional wisdom is recovered when the dynamic reflection symmetry
is introduced instead of the static one.Comment: 14 pages, Revtex, 4 figures (one PS figure file upon request)
(submitted to Phy. Rev. E
Critical behavior of a one-dimensional monomer-dimer reaction model with lateral interactions
A monomer-dimer reaction lattice model with lateral repulsion among the same
species is studied using a mean-field analysis and Monte Carlo simulations. For
weak repulsions, the model exhibits a first-order irreversible phase transition
between two absorbing states saturated by each different species. Increasing
the repulsion, a reactive stationary state appears in addition to the saturated
states. The irreversible phase transitions from the reactive phase to any of
the saturated states are continuous and belong to the directed percolation
universality class. However, a different critical behavior is found at the
point where the directed percolation phase boundaries meet. The values of the
critical exponents calculated at the bicritical point are in good agreement
with the exponents corresponding to the parity-conserving universality class.
Since the adsorption-reaction processes does not lead to a non-trivial local
parity-conserving dynamics, this result confirms that the twofold symmetry
between absorbing states plays a relevant role in determining the universality
class. The value of the exponent , which characterizes the
fluctuations of an interface at the bicritical point, supports the
Bassler-Brown's conjecture which states that this is a new exponent in the
parity-conserving universality class.Comment: 19 pages, 22 figures, to be published in Phys. Rev
Initial operation of a solar heating and cooling system in a full-scale solar building test facility
The Solar Building Test Facility (SBTF) was constructed to advance the technology for heating and cooling of office buildings with solar energy. Its purposes are to (1) test system components which include high-performing collectors, (2) test the performance of a complete solar heating and cooling system, (3) investigate component interactions, and (4) investigate durability, maintenance and reliability of components. The SBTF consists of a 50,000 square foot office building modified to accept solar heated water for operation of an absorption air conditioner and for the baseboard heating system. A 12,666 square foot solar collector field with a 30,000 gallon storage tank provides the solar heated water. A description of the system and the collectors selected is printed along with the objectives, test approach, expected system performance, and some preliminary results
Layer Features of the Lattice Gas Model for Self-Organized Criticality
A layer-by-layer description of the asymmetric lattice gas model for
1/f-noise suggested by Jensen [Phys. Rev. Lett. 64, 3103 (1990)] is presented.
The power spectra of the lattice layers in the direction perpendicular to the
particle flux is studied in order to understand how the white noise at the
input boundary evolves, on the average, into 1/f-noise for the system. The
effects of high boundary drive and uniform driving force on the power spectrum
of the total number of diffusing particles are considered. In the case of
nearest-neighbor particle interactions, high statistics simulation results show
that the power spectra of single lattice layers are characterized by different
exponents such that as one approaches the outer
boundary.Comment: LaTeX, figures upon reques
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