1,411 research outputs found

    Consortia Focused on Photovoltaic R&D, Manufacturing, and Testing: A Review of Existing Models and Structures

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    As the U.S. Department of Energy\u27s (DOE\u27s) Solar Energy Technologies Program prepares to initiate a new cost-shared research and development (R&D) effort on photovoltaic (PV) manufacturing, it is useful to review the experience to date with consortia focused on PV R&D, manufacturing, and testing. Information was gathered for this report by conducting interviews and accessing Web sites of 14 U.S. consortia and four European consortia, each with either a primary focus on or an emerging interest in PV technology R&D, manufacturing, or testing. Additional input was collected from several workshops held by the DOE and National Academy of Sciences (NAS) in 2009, which examined the practical steps -- including public-private partnerships and policy support -- necessary to enhance the United States\u27 capacity to competitively manufacture photovoltaics. This report categorizes the 18 consortia into three groups: university-led consortia, industry-led consortia, and manufacturing and testing facilities consortia. The first section summarizes the organizations within the different categories, with a particular focus on the key benefits and challenges for each grouping. The second section provides a more detailed overview of each consortium, including the origins, goals, organization, membership, funding sources, and key contacts. This survey is a useful resource for stakeholders interested in PV manufacturing R&D, but should not imply endorsement of any of these groups

    Basic Forest Cover Mapping Using Digitized Remote Sensor Data and Automatic Data Processing Techniques

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    Increasing demands on the forest resource will necessitate increasingly more intensive management in the future. In order to achieve this goal, reliable and timely information over large geographic areas will be required. Remote sensing techniques offer much potential for the procurement of such information. This research, then, was pointed toward study of that potential. Four objectives were established as follows: 1) to determine the optimum number of the available twelve multispectral scanner (MSS) wavelength bands to use for forest cover mapping with automatic data processing (ADP) techniques; 2) to determine the current capability to map basic forest cover using MSS data and ADP techniques; 3) to determine the relative utility, to forest cover mapping, of the four spectral regions available in the twelve-channel MSS data (i.e. visible, and near, middle and thermal infrared); and 4) to compare the accuracy of digitized color infrared photography with that of MSS data for forest cover mapping using ADP techniques. In attaining the first objective, statistics defining the six cover type classes of interest (deciduous forest, coniferous forest, water, forage, corn, and soybeans) were calculated and used by the computer as a basis for the selection of best wavelength band combinations ranging in size from one through ten wavelength bands each. With the spectral information contained in each of these combinations, and with all twelve channels, the entire test area was classified into the six defined classes, using the LARSYS programs. Tests of the computer\u27s performance indicated that the use of five wavelength bands would fulfill the dual requirements of adequate accuracy and moderate computer time. In fulfilling the second objective, the automatically selected best combination of five channels (one each from the green and red visible wavelengths, and the near, middle and thermal infrared wavelengths) produced classification accuracies in excess of 90 percent for deciduous and coniferous forest. When these two classes were grouped, the accuracy for combined forest was in excess of 95 percent. The use of all twelve channels caused only a slight increase in overall accuracy. In satisfying the third objective, the LARSYS feature selection processor was allowed to consider wavelength bands constituting only various subsets of the four spectral regions. On this basis, it selected a number of five-channel combinations. Classifications performed by these various channel combinations indicate that the visible wavelengths are sufficiently accurate for classifying combined forest, but inadequate for differentiating between deciduous and coniferous forest. The infrared channels separated the two forest classes with reasonable accuracy, but allowed confusion between forest and the agricultural classes. The deletion of either the near or the middle infrared individually, did not reduce accuracies, but, when both were deleted, accuracies dropped drastically. The deletion of the thermal infrared had little effect on forest cover mapping but did allow considerable confusion among the agricultural cover types. These results indicate that the thermal infrared is desirable, but not necessary, for basic forest cover mapping, and that accurate classification of deciduous and coniferous forest cover can be achieved with the visible plus either the near or middle infrared spectral regions. To meet the fourth objective, small-scale color infrared photography, acquired the same day over the test site, was color separated, digitized in three wavelength bands and, automatically classified. In general, the digitized photography was inadequate for automatic forest cover mapping and compared poorly to the MSS data results when similar wavelength bands were used. These results were apparently caused by the narrower dynamic range, poorer spectral resolution, and uneven illumination (due to vignetting and the anti-solar point) of the photographic data

    Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC

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    The uncertainty on the calorimeter energy response to jets of particles is derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the calorimeter response to single isolated charged hadrons is measured and compared to the Monte Carlo simulation using proton-proton collisions at centre-of-mass energies of sqrt(s) = 900 GeV and 7 TeV collected during 2009 and 2010. Then, using the decay of K_s and Lambda particles, the calorimeter response to specific types of particles (positively and negatively charged pions, protons, and anti-protons) is measured and compared to the Monte Carlo predictions. Finally, the jet energy scale uncertainty is determined by propagating the response uncertainty for single charged and neutral particles to jets. The response uncertainty is 2-5% for central isolated hadrons and 1-3% for the final calorimeter jet energy scale.Comment: 24 pages plus author list (36 pages total), 23 figures, 1 table, submitted to European Physical Journal

    Standalone vertex finding in the ATLAS muon spectrometer

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    A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at √s = 7 TeV collected with the ATLAS detector at the LHC during 2011

    The extraordinary evolutionary history of the reticuloendotheliosis viruses

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    The reticuloendotheliosis viruses (REVs) comprise several closely related amphotropic retroviruses isolated from birds. These viruses exhibit several highly unusual characteristics that have not so far been adequately explained, including their extremely close relationship to mammalian retroviruses, and their presence as endogenous sequences within the genomes of certain large DNA viruses. We present evidence for an iatrogenic origin of REVs that accounts for these phenomena. Firstly, we identify endogenous retroviral fossils in mammalian genomes that share a unique recombinant structure with REVs—unequivocally demonstrating that REVs derive directly from mammalian retroviruses. Secondly, through sequencing of archived REV isolates, we confirm that contaminated Plasmodium lophurae stocks have been the source of multiple REV outbreaks in experimentally infected birds. Finally, we show that both phylogenetic and historical evidence support a scenario wherein REVs originated as mammalian retroviruses that were accidentally introduced into avian hosts in the late 1930s, during experimental studies of P. lophurae, and subsequently integrated into the fowlpox virus (FWPV) and gallid herpesvirus type 2 (GHV-2) genomes, generating recombinant DNA viruses that now circulate in wild birds and poultry. Our findings provide a novel perspective on the origin and evolution of REV, and indicate that horizontal gene transfer between virus families can expand the impact of iatrogenic transmission events

    Search for squarks and gluinos with the ATLAS detector in final states with jets and missing transverse momentum using √s=8 TeV proton-proton collision data

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    A search for squarks and gluinos in final states containing high-p T jets, missing transverse momentum and no electrons or muons is presented. The data were recorded in 2012 by the ATLAS experiment in s√=8 TeV proton-proton collisions at the Large Hadron Collider, with a total integrated luminosity of 20.3 fb−1. Results are interpreted in a variety of simplified and specific supersymmetry-breaking models assuming that R-parity is conserved and that the lightest neutralino is the lightest supersymmetric particle. An exclusion limit at the 95% confidence level on the mass of the gluino is set at 1330 GeV for a simplified model incorporating only a gluino and the lightest neutralino. For a simplified model involving the strong production of first- and second-generation squarks, squark masses below 850 GeV (440 GeV) are excluded for a massless lightest neutralino, assuming mass degenerate (single light-flavour) squarks. In mSUGRA/CMSSM models with tan β = 30, A 0 = −2m 0 and μ > 0, squarks and gluinos of equal mass are excluded for masses below 1700 GeV. Additional limits are set for non-universal Higgs mass models with gaugino mediation and for simplified models involving the pair production of gluinos, each decaying to a top squark and a top quark, with the top squark decaying to a charm quark and a neutralino. These limits extend the region of supersymmetric parameter space excluded by previous searches with the ATLAS detector

    Measurement of inclusive two-particle angular correlations in pp collisions with the ATLAS detector at the LHC

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    We present a measurement of two-particle angular correlations in proton- proton collisions at s√=900 GeV and 7 TeV. The collision events were collected during 2009 and 2010 with the ATLAS detector at the Large Hadron Collider using a single-arm minimum bias trigger. Correlations are measured for charged particles produced in the kinematic range of transverse momentum p T  > 100 MeV and pseudorapidity |η| < 2.5. A complex structure in pseudorapidity and azimuth is observed at both collision energies. Results are compared to pythia 8 and herwig++ as well as to the AMBT2B, DW and Perugia 2011 tunes of pythia 6. The data are not satisfactorily described by any of these models
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