18,682 research outputs found
PV large systems project
Near term photovoltaic central-station markets are analyzed. Cost effectiveness of photovoltaic plants is determined in terms of reduction of oil consumption. The breakeven photovoltaic system cost vs oil-steam power generation is given. The value of photovoltaic power plants in Southern California and in Los Angelos is given in terms of fuel savings and capacity value. The potential value of third party financing, facilitated by Federal and state tax incentives is analyzed
Central station applications planning activities and supporting studies
The application of photovoltaic technology in central station (utility) power generation plants is considered. A program of data collection and analysis designed to provide additional information about the subset of the utility market that was identified as the initial target for photovoltaic penetration, the oil-dependent utilities (especially muncipals) of the U.S. Sunbelt, is described along with a series of interviews designed to ascertain utility industry opinions about the National Photovoltaic Program as it relates to central station applications
The importance of community development for health and well-being
Public health - Economic aspects
Getting In On the Act: How Arts Groups are Creating Opportunities for Active Participation
Arts participation is being redefined as people increasingly choose to engage with art in new, more active and expressive ways. This movement carries profound implications, and fresh opportunities, for the nonprofit arts sector.We are in the midst of a seismic shift in cultural production, moving from a "sit-back-and-be-told culture" to a "making-and-doing-culture." Active or participatory arts practices are emerging from the fringes of the Western cultural tradition to capture the collective imagination. Many forces have conspired to lead us to this point. The sustained economic downturn that began in 2008, rising ticket prices, the pervasiveness of social media, the roliferation of digital content and rising expectations for self-guided, on-demand, customized experiences have all contributed to a cultural environment primed for active arts practice. This shift calls for a new equilibrium in the arts ecology and a new generation of arts leaders ready to accept, integrate and celebrate all forms of cultural practice. This is, perhaps, the defining challenge of our time for artists, arts organizations and their supporters -- to embrace a more holistic view of the cultural ecology and identify new possibilities for Americans to engage with the arts.How can arts institutions adapt to this new environment?Is participatory practice contradictory to, or complementary to, a business model that relies on professional production and consumption?How can arts organizations enter this new territory without compromising their values r artistic ideals?This report aims to illuminate a growing body of practice around participatory engagement (with various illustrative case studies profiled at the end) and dispel some of the anxiety surrounding this sphere of activity
Gravitational waves from binary systems in circular orbits: Convergence of a dressed multipole truncation
The gravitational radiation originating from a compact binary system in
circular orbit is usually expressed as an infinite sum over radiative multipole
moments. In a slow-motion approximation, each multipole moment is then
expressed as a post-Newtonian expansion in powers of v/c, the ratio of the
orbital velocity to the speed of light. The bare multipole truncation of the
radiation consists in keeping only the leading-order term in the post-Newtonian
expansion of each moment, but summing over all the multipole moments. In the
case of binary systems with small mass ratios, the bare multipole series was
shown in a previous paper to converge for all values v/c < 2/e, where e is the
base of natural logarithms. In this paper, we extend the analysis to a dressed
multipole truncation of the radiation, in which the leading-order moments are
corrected with terms of relative order (v/c)^2 and (v/c)^3. We find that the
dressed multipole series converges also for all values v/c < 2/e, and that it
coincides (within 1%) with the numerically ``exact'' results for v/c < 0.2.Comment: 9 pages, ReVTeX, 1 postscript figur
Darth Fader: Using wavelets to obtain accurate redshifts of spectra at very low signal-to-noise
We present the DARTH FADER algorithm, a new wavelet-based method for
estimating redshifts of galaxy spectra in spectral surveys that is particularly
adept in the very low SNR regime. We use a standard cross-correlation method to
estimate the redshifts of galaxies, using a template set built using a PCA
analysis on a set of simulated, noise-free spectra. Darth Fader employs wavelet
filtering to both estimate the continuum & to extract prominent line features
in each galaxy spectrum. A simple selection criterion based on the number of
features present in the spectrum is then used to clean the catalogue: galaxies
with fewer than six total features are removed as we are unlikely to obtain a
reliable redshift estimate. Applying our wavelet-based cleaning algorithm to a
simulated testing set, we successfully build a clean catalogue including
extremely low signal-to-noise data (SNR=2.0), for which we are able to obtain a
5.1% catastrophic failure rate in the redshift estimates (compared with 34.5%
prior to cleaning). We also show that for a catalogue with uniformly mixed SNRs
between 1.0 & 20.0, with realistic pixel-dependent noise, it is possible to
obtain redshifts with a catastrophic failure rate of 3.3% after cleaning (as
compared to 22.7% before cleaning). Whilst we do not test this algorithm
exhaustively on real data, we present a proof of concept of the applicability
of this method to real data, showing that the wavelet filtering techniques
perform well when applied to some typical spectra from the SDSS archive. The
Darth Fader algorithm provides a robust method for extracting spectral features
from very noisy spectra. The resulting clean catalogue gives an extremely low
rate of catastrophic failures, even when the spectra have a very low SNR. For
very large sky surveys, this technique may offer a significant boost in the
number of faint galaxies with accurately determined redshifts.Comment: 22 pages, 15 figures. Accepted for publication in Astronomy &
Astrophysic
Restricted equilibrium ensembles: Exact equation of state of a model glass
We investigate the thermodynamic properties of a toy model of glasses: a
hard-core lattice gas with nearest neighbor interaction in one dimension. The
time-evolution is Markovian, with nearest-neighbor and next-nearest neighbor
hoppings, and the transition rates are assumed to satisfy detailed balance
condition, but the system is non-ergodic below a glass temperature. Below this
temperature, the system is in restricted thermal equilibrium, where both the
number of sectors, and the number of accessible states within a sector grow
exponentially with the size of the system. Using partition functions that sum
only over dynamically accessible states within a sector, and then taking a
quenched average over the sectors, we determine the exact equation of state of
this system.Comment: 6 pages, 2 figure
Accessing Patient Records in Virtual Healthcare Organisations
The ARTEMIS project is developing a semantic web service based P2P interoperability infrastructure for healthcare information systems that will allow healthcare providers to securely share patient records within virtual healthcare organisations. Authorisation decisions to access patient records across organisation boundaries can be very dynamic and must occur within a strict legislative framework. In ARTEMIS we are developing a dynamic authorisation mechanism called PBAC that provides a means of contextual and process oriented access control to enforce healthcare business processes. PBAC demonstrates how healthcare providers can dynamically share patient records for care pathways across organisation boundaries
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