319 research outputs found
Design and Development of Laboratory Single-Axis PV Module Tracker
Solar energy is an integral part of the renewable energy industry. Advanced solar farms actively track solar movement and update solar panel angles to maximize the systemâs output power. Cal Poly boasts its own Solar Farm that features a single-axis tracking system. Single-axis tracking aims to get panels as close to perpendicular as possible given the panel arrangements and given the time of year. Single-axis tracking is a more robust measurement and tracking option. Single-axis tracking systems usually only have East-West panel arc movement, following the sunâs rotation. Dual-axis trackers have both East-West and North-South panel arc movements. Dual-axis systems have the ability to shift their North-South angle to better face the sun as the seasons change, based on GPS location. Solar panels generate the most power when receiving the highest light intensity. Single-axis systems generally cost less than Dual-axis. One less axis of motion translates to fewer mechanical parts, fewer motor controllers, and ultimately a more durable system. To account for the inability to directly face the sun year round, students will study how to eliminate inter-row shading between panels to maximize power production.
To observe and improve the single-axis tracking system, a laboratory model of the solar farm will be created. Identical solar panels to the Cal Poly panels will be integrated with a solar tracking embedded system. The system will be tested on available test panels in conjunction with a specialized angle tracking measurement network. Students will alter and study the system, accommodating for variables that are not accounted for in the current static algorithm. The new testing system will allow students to study the issues present in the farm and to develop a proposal to improve the power production performance at the farm. In addition, students will learn the fundamentals of single-axis tracking. The laboratory model will be adaptable regardless of the location and terrain of the solar farm, and will tilt the panels in the most optimal angle for the network of arrays in a typical farm
Multiple Gluon Effects in at FNAL Energies: Semi-Analytical Results
We apply our Yennie-Frautschi-Suura exponentiated cross section formulas for
the parton processes q + {^(} \bar q {^)}{^\prime} \ra q{^\prime}{^\prime} +
{^(} \bar q {^)}{^\prime}{^\prime}{^\prime} + n(G) to the process q + \bar q
\ra t + \bar t + n(G) at FNAL energies, where G is a QCD gluon. We use
semi-analytical methods to compute the ratio ,
where is our soft gluon YFS exponentiated cross section and
is the Born cross section. For TeV, we get
, respectively, for for example. These results are
not inconsistent with the recent observations by CDF and D0.Comment: 6 pages, latex replaces postscript at archiver's reques
SuperScentâa database of flavors and scents
Volatiles are efficient mediators of chemical communication acting universally as attractant, repellent or warning signal in all kingdoms of life. Beside this broad impact volatiles have in nature, scents are also widely used in pharmaceutical, food and cosmetic industries, so the identification of new scents is of great industrial interest. Despite this importance as well as the vast number and diversity of volatile compounds, there is currently no comprehensive public database providing information on structure and chemical classification of volatiles. Therefore, the database SuperScent was established to supply users with detailed information on the variety of odor components. The version of the database presented here comprises the 2D/3D structures of approximately 2100 volatiles and around 9200 synonyms as well as physicochemical properties, commercial availability and references. The volatiles are classified according to their origin, functionality and odorant groups. The information was extracted from the literature and web resources. SuperScent offers several search options, e.g. name, Pubchem ID number, species, functional groups, or molecular weight. SuperScent is available online at: http://bioinformatics.charite.de/superscent
Density functional theory calculations of the carbon ELNES of small diameter armchair and zigzag nanotubes: core-hole, curvature and momentum transfer orientation effects
We perform density functional theory calculations on a series of armchair and
zigzag nanotubes of diameters less than 1nm using the all-electron
Full-Potential(-Linearised)-Augmented-Plane-Wave (FPLAPW) method. Emphasis is
laid on the effects of curvature, the electron beam orientation and the
inclusion of the core-hole on the carbon electron energy loss K-edge. The
electron energy loss near-edge spectra of all the studied tubes show strong
curvature effects compared to that of flat graphene. The curvature induced
hybridisation is shown to have a more drastic effect on the
electronic properties of zigzag tubes than on those of armchair tubes. We show
that the core-hole effect must be accounted for in order to correctly reproduce
electron energy loss measurements. We also find that, the energy loss near edge
spectra of these carbon systems are dominantly dipole selected and that they
can be expressed simply as a proportionality with the local momentum projected
density of states, thus portraying the weak energy dependence of the transition
matrix elements. Compared to graphite, the ELNES of carbon nanotubes show a
reduced anisotropy.Comment: 25 pages, 15 figures, revtex4 submitted for publication to Phys. Rev.
Mineralogy, Petrology, Chronology, and Exposure History of the Chelyabinsk Meteorite and Parent Body
The Chelyabinsk meteorite fall on February 15, 2013 attracted much more attention worldwide than do most falls. A consortium led by JSC received 3 masses of Chelyabinsk (Chel-101, -102, -103) that were collected shortly after the fall and handled with care to minimize contamination. Initial studies were reported in 2013; we have studied these samples with a wide range of analytical techniques to better understand the mineralogy, petrology, chronology and exposure history of the Chelyabinsk parent body
Paleo-sea surface temperature calculations in the equatorial east Atlantic from Mg/Ca ratios in planktic foraminifera: A comparison to sea surface temperature estimates from UK'37, oxygen isotopes, and foraminiferal transfer function
We present two âŒ270 kyr paleo-sea surface temperature (SST) records from the Equatorial Divergence and the South Equatorial Current derived from Mg/Ca ratios in the planktic foraminifer Globigerinoides sacculifer. The present study suggests that the magnesium signature of G. sacculifer provides a seasonal SST estimate from the upper âŒ50 m of the water column generated during upwelling in austral low-latitude fall/winter. Common to both down-core records is a glacial-interglacial amplitude of âŒ3°â3.5°C for the last climatic changes and lower Holocene and glacial oxygen isotope stage 2 temperatures compared with interglacial stage 5.5 and glacial stage 6 temperatures, respectively. The comparison to published SST estimates from alkenones, oxygen isotopes, and foraminiferal transfer function from the same core material pinpoints discrepancies and conformities between methods
Isotopic evidence (<sup>87</sup>Sr/<sup>86</sup>Sr, ÎŽ<sup>7</sup>Li) for alteration of the oceanic crust at deep-rooted mud volcanoes in the Gulf of Cadiz, NE Atlantic Ocean [(Sr-87/Sr-86, delta Li-7) ]
The chemical and isotopic composition of pore fluids is presented for five deep-rooted mud volcanoes aligned on a transect across the Gulf of Cadiz continental margin at water depths between 350 and 3860 m. Generally decreasing interstitial Li concentrations and Sr-87/Sr-86 ratios with increasing distance from shore are attributed to systematically changing fluid sources across the continental margin. Although highest Li concentrations at the near-shore mud volcanoes coincide with high salinities derived from dissolution of halite and late-stage evaporites, clayey, terrigenous sediments are identified as the ultimate Li source to all pore fluids investigated. Light delta Li-7 values, partly close to those of hydrothermal vent fluids (delta Li-7: +11.9 parts per thousand), indicate that Li has been mobilized during high-temperature fluid/sediment or fluid/rock interactions in the deep sub-surface. Intense leaching of terrigenous clay has led to radiogenic Sr-87/Sr-86 ratios (similar to 0.7106) in pore fluids of the near-shore mud volcanoes. In contrast, non-radiogenic Sr-87/Sr-86 ratios (similar to 0.7075) at the distal locations are attributed to admixing of a basement-derived fluid component, carrying an isotopic signature from interaction with the basaltic crust. This inference is substantiated by temperature constraints from Li isotope equilibrium calculations suggesting exchange processes at particularly high temperatures (>200 degrees C) for the least radiogenic pore fluids of the most distal location.Advective pore fluids in the off-shore reaches of the Gulf of Cadiz are influenced by successive exchange processes with both oceanic crust and terrigenous, fine-grained sediments, resulting in a chemical and isotopic signature similar to that of fluids in near-shore ridge flank hydrothermal systems. This suggests that deep-rooted mud volcanoes in the Gulf of Cadiz represent a fluid pathway intermediate between mid-ocean ridge hydrothermal vent and shallow, marginal cold seep. Due to the thicker sediment coverage and slower fluid advection rates, the overall geochemical signature is shifted towards the sediment-diagenetic signal compared to ridge flank hydrothermal environments. (C) 2009 Elsevier Ltd. All rights reserved
ISO observations of the interacting galaxy Markarian 297: with the powerful supernova remnant 1982aa
Markarian (Mkn) 297 is a complex system with two interacting galaxies.
Observations were made with ISO using ISOCAM, ISOPHOT and LWS. We present
ISOCAM maps at 6.7, 7.7, 12 and 14.3 microns which, with PHT-S spectrometry of
the central interacting region, probe the dust obscured star formation and dust
properties. ISOCAM reveals that the strongest emission region in the four MIR
bands is completely unremarkable at visible and near-IR (e.g. 2MASS)
wavelengths, and does not coincide with the nuclear region of either colliding
galaxy. It shares this striking characteristic with the overlap region of the
colliding galaxies in the Antennae (NGC 4038, 4039), the intragroup region of
Stephan's Quintet, and IC 694 in the interacting system Arp 299. At 15 microns,
the hidden source in Mkn 297 is, respectively, 14.6 and 3.8 times more luminous
than the hidden sources in the Antennae (NGC 4038/4039) and Stephan's Quintet.
Numerical simulations indicate that we see the Mkn 297 interaction about 1.5 x
10e8 years after the collision. ISOCAM shows knots and ridges of emission. The
14.3/7.7 micron ratio map implies widespread strong star formation. Strong
emission features were detected in the ISOPHOT spectrum, while [OI], [OIII] and
[CII] emission lines were seen with LWS. Using data from the three instruments,
luminosities and masses for two dust components were determined. The total
infrared luminosity is approximately 10e11 L_sol, marginally a LIRG. A 1979
supernova generated one of the most powerful known radio remnants (SN 1982aa)
close to the strongest MIR source and identified with star forming region 14 in
the optical. This exceptional supernova explosion may have been accompanied by
a GRB, and a search for a GRB in this direction in contemporaneous satellite
data is recommended.Comment: Accepted for publication in Astronomy and Astrophysics Updated to
better use recent SN/GRB work and tune terminology in Sec. 4.
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