252 research outputs found
Phase 1 of the automated array assembly task of the low cost silicon solar array project
The results of a study of process variables and solar cell variables are presented. Interactions between variables and their effects upon control ranges of the variables are identified. The results of a cost analysis for manufacturing solar cells are discussed. The cost analysis includes a sensitivity analysis of a number of cost factors
Phase 1 of the automated array assembly task of the low cost silicon solar array project
The state of technology readiness for the automated production of solar cells and modules is reviewed. Individual process steps and process sequences for making solar cells and modules were evaluated both technically and economically. High efficiency with a suggested cell goal of 15% was stressed. It is concluded that the technology exists to manufacture solar cells which will meet program goals
Chemical Abundances in Metal-Rich Bulge-like Stars
We have derived chemical abundances for Ca, Ti, Si, Mg, O, Na, Al, Ni, Co and Cr for a sample of stars with peculiar kinematics and probable origin near the bulge. Our sample stars are in the metallicity range = −0.8 ≤ [Fe/H] ≤ +0.6 dex, and have small pericentric distances, Rp ≤ 3.5 kpc, small scale height, with Zmax +0.3 dex. Compared to bulge stars, such elements are deficient in our sample stas. For the iron-peak elements Cr and Ni we have found a slightly overabundant behavior relative to both thin and thick disks distributions in the metal-poor range, and a smooth decreasing trend for [Cr/Fe] for stars in the supersolar regime. [Co/Fe] ratios track the solar value in the metal-poor range, and show an underabundant behavior relative do thin disk stars for metallicities [Fe/H] > 0.0 de
The Automated Array Assembly Task of the Low-cost Silicon Solar Array Project, Phase 2
An advanced process sequence for manufacturing high efficiency solar cells and modules in a cost-effective manner is discussed. Emphasis is on process simplicity and minimizing consumed materials. The process sequence incorporates texture etching, plasma processes for damage removal and patterning, ion implantation, low pressure silicon nitride deposition, and plated metal. A reliable module design is presented. Specific process step developments are given. A detailed cost analysis was performed to indicate future areas of fruitful cost reduction effort. Recommendations for advanced investigations are included
Anisotropic Galactic Outflows and Enrichment of the Intergalactic Medium. I: Monte Carlo Simulations
We have developed an analytical model to describe the evolution of
anisotropic galactic outflows. With it, we investigate the impact of varying
opening angle on galaxy formation and the evolution of the IGM. We have
implemented this model in a Monte Carlo algorithm to simulate galaxy formation
and outflows in a cosmological context. Using this algorithm, we have simulated
the evolution of a comoving volume of size [12h^(-1)Mpc]^3 in the LCDM
universe. Starting from a Gaussian density field at redshift z=24, we follow
the formation of ~20,000 galaxies, and simulate the galactic outflows produced
by these galaxies. When these outflows collide with density peaks, ram pressure
stripping of the gas inside the peak may result. This occurs in around half the
cases and prevents the formation of galaxies. Anisotropic outflows follow the
path of least resistance, and thus travel preferentially into low-density
regions, away from cosmological structures (filaments and pancakes) where
galaxies form. As a result, the number of collisions is reduced, leading to the
formation of a larger number of galaxies. Anisotropic outflows can
significantly enrich low-density systems with metals. Conversely, the
cross-pollution in metals of objects located in a common cosmological
structure, like a filament, is significantly reduced. Highly anisotropic
outflows can travel across cosmological voids and deposit metals in other,
unrelated cosmological structures.Comment: 32 pages, 9 figures (2 color). Revised version accepted in Ap
FEROS Abundance Analysis of 21 Bulgelike SMR Stars
We analyze a sample of 21 super-metal-rich (SMR) stars, using high-resolution échelle spectra obtained with the Fiber-fed Extended Range Optical Spectrograph at the 1.5m ESO telescope. The metallicities are in the range 0.07 ≤ [Fe/H] ≤ 0.45, 3 of them in common with Pompéia et al. (2009). Geneva photometry, astrometric data from Hipparcos, and radial velocities from CORAVEL are available for these stars. The peculiar kinematics suggests the thin disk close to the bulge as the probable birthplace of these stars (Grenon 1999). From Hipparcos data, it appears that the turnoff of this population indicates an age of 10-11 Gyr (Grenon 1999). Detailed analysis of the sample stars is carried out, and atmospheric parameters are derived from spectroscopic and photometric determinations. Oxygen abundances of these stars are derived, and [O/Fe] overabundances up to +0.35 are foun
Processing experiments on non-Czochralski silicon sheet
A program is described which supports and promotes the development of processing techniques which may be successfully and cost-effectively applied to low-cost sheets for solar cell fabrication. Results are reported in the areas of process technology, cell design, cell metallization, and production cost simulation
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