Thermal performance of a photographic laboratory process: Solar Hot Water System

The thermal performance of a solar process hot water system is described. The system was designed to supply 22,000 liters (5,500 gallons) per day of 66 C (150 F) process water for photographic processing. The 328 sq m (3,528 sq. ft.) solar field has supplied 58% of the thermal energy for the system. Techniques used for analyzing various thermal values are given. Load and performance factors and the resulting solar contribution are discussed

Absence of orbital-selective Mott transition in Ca_2-xSr_xRuO4

Quasi-particle spectra of the layer perovskite Sr$_2$RuO$_4$ are calculated within Dynamical Mean Field Theory for increasing values of the on-site Coulomb energy $U$. At small $U$ the planar geometry splits the $t_{2g}$ bands near $E_F$ into a wide, two-dimensional $d_{xy}$ band and two narrow, nearly one-dimensional $d_{xz,yz}$ bands. At larger $U$, however, the spectral distribution of these states exhibit similar correlation features, suggesting a common metal-insulator transition for all $t_{2g}$ bands at the same critical $U$.Comment: 4 pages, 4 figure

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

One Dimensional Nonequilibrium Kinetic Ising Models with Branching Annihilating Random Walk

Nonequilibrium kinetic Ising models evolving under the competing effect of spin flips at zero temperature and nearest neighbour spin exchanges at $T=\infty$ are investigated numerically from the point of view of a phase transition. Branching annihilating random walk of the ferromagnetic domain boundaries determines the steady state of the system for a range of parameters of the model. Critical exponents obtained by simulation are found to agree, within error, with those in Grassberger's cellular automata.Comment: 10 pages, Latex, figures upon request, SZFKI 05/9

Honeycomb lattice polygons and walks as a test of series analysis techniques

We have calculated long series expansions for self-avoiding walks and polygons on the honeycomb lattice, including series for metric properties such as mean-squared radius of gyration as well as series for moments of the area-distribution for polygons. Analysis of the series yields accurate estimates for the connective constant, critical exponents and amplitudes of honeycomb self-avoiding walks and polygons. The results from the numerical analysis agree to a high degree of accuracy with theoretical predictions for these quantities.Comment: 16 pages, 9 figures, jpconf style files. Presented at the conference "Counting Complexity: An international workshop on statistical mechanics and combinatorics." In celebration of Prof. Tony Guttmann's 60th birthda

A classical statistical model for distributions of escape events in swept-bias Josephson junctions

We have developed a model for experiments in which the bias current applied to a Josephson junction is slowly increased from zero until the junction switches from its superconducting zero-voltage state, and the bias value at which this occurs is recorded. Repetition of such measurements yields experimentally determined probability distributions for the bias current at the moment of escape. Our model provides an explanation for available data on the temperature dependence of these escape peaks. When applied microwaves are included we observe an additional peak in the escape distributions and demonstrate that this peak matches experimental observations. The results suggest that experimentally observed switching distributions, with and without applied microwaves, can be understood within classical mechanics and may not exhibit phenomena that demand an exclusively quantum mechanical interpretation.Comment: Eight pages, eight figure

Perimeter Generating Functions For The Mean-Squared Radius Of Gyration Of Convex Polygons

We have derived long series expansions for the perimeter generating functions of the radius of gyration of various polygons with a convexity constraint. Using the series we numerically find simple (algebraic) exact solutions for the generating functions. In all cases the size exponent $\nu=1$.Comment: 8 pages, 1 figur

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