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  • American Institute of Physics (AIP)  (2)
  • Nature Publishing Group  (2)
  • Geological Society of America (GSA)  (1)
  • 1
    Publication Date: 2014-12-17
    Description: Interior Antarctica is among the most remote places on Earth and was thought to be beyond the reach of human impacts when Amundsen and Scott raced to the South Pole in 1911. Here we show detailed measurements from an extensive array of 16 ice cores quantifying substantial toxic heavy metal lead pollution at South Pole and throughout Antarctica by 1889 – beating polar explorers by more than 22 years. Unlike the Arctic where lead pollution peaked in the 1970s, lead pollution in Antarctica was as high in the early 20th century as at any time since industrialization. The similar timing and magnitude of changes in lead deposition across Antarctica, as well as the characteristic isotopic signature of Broken Hill lead found throughout the continent, suggest that this single emission source in southern Australia was responsible for the introduction of lead pollution into Antarctica at the end of the 19th century and remains a significant source today. An estimated 660 t of industrial lead have been deposited over Antarctica during the past 130 years as a result of mid-latitude industrial emissions, with regional-to-global scale circulation likely modulating aerosol concentrations. Despite abatement efforts, significant lead pollution in Antarctica persists into the 21st century.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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  • 2
    Publication Date: 2022-05-26
    Description: © The Author(s), 2014. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Scientific Reports 4 (2014): 5848, doi:10.1038/srep05848.
    Description: Interior Antarctica is among the most remote places on Earth and was thought to be beyond the reach of human impacts when Amundsen and Scott raced to the South Pole in 1911. Here we show detailed measurements from an extensive array of 16 ice cores quantifying substantial toxic heavy metal lead pollution at South Pole and throughout Antarctica by 1889 – beating polar explorers by more than 22 years. Unlike the Arctic where lead pollution peaked in the 1970s, lead pollution in Antarctica was as high in the early 20th century as at any time since industrialization. The similar timing and magnitude of changes in lead deposition across Antarctica, as well as the characteristic isotopic signature of Broken Hill lead found throughout the continent, suggest that this single emission source in southern Australia was responsible for the introduction of lead pollution into Antarctica at the end of the 19th century and remains a significant source today. An estimated 660 t of industrial lead have been deposited over Antarctica during the past 130 years as a result of mid-latitude industrial emissions, with regional-to-global scale circulation likely modulating aerosol concentrations. Despite abatement efforts, significant lead pollution in Antarctica persists into the 21st century.
    Description: This work primarily was supported by the U.S. National Science Foundation Division of Polar Programs (research grants 9903744, 0538427, 0538416, 0968391, 1142166, 0632031; instrument grants 0216552, 0421412).
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/vnd.ms-excel
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  • 3
    Publication Date: 2013-08-24
    Description: High-latitude landscape evolution processes have the potential to preserve old, relict surfaces through burial by cold-based, nonerosive glacial ice. To investigate landscape history and age in the high Arctic, we analyzed in situ cosmogenic 10 Be and 26 Al in 33 rocks from Upernavik, northwest Greenland. We sampled adjacent bedrock-boulder pairs along a 100 km transect at elevations up to 1000 m above sea level. Bedrock samples gave significantly older apparent exposure ages than corresponding boulder samples, and minimum limiting ages increased with elevation. Two-isotope calculations ( 26 Al/ 10 Be) on 20 of the 33 samples yielded minimum limiting exposure durations up to 112 k.y., minimum limiting burial durations up to 900 k.y., and minimum limiting total histories up to 990 k.y. The prevalence of 10 Be and 26 Al inherited from previous periods of exposure, especially in bedrock samples at high elevation, indicates that these areas record long and complex surface exposure histories, including significant periods of burial with little subglacial erosion. The long total histories suggest that these high-elevation surfaces were largely preserved beneath cold-based, nonerosive ice or snowfields for at least the latter half of the Quaternary. Because of high concentrations of inherited nuclides, only the six youngest boulder samples appear to record the timing of ice retreat. These six samples suggest deglaciation of the Upernavik coast at 11.3 ± 0.5 ka (average ± 1 standard deviation). There is no difference in deglaciation age along the 100 km sample transect, indicating that the ice-marginal position retreated rapidly at rates of ~120 m yr –1 .
    Print ISSN: 0016-7606
    Electronic ISSN: 1943-2674
    Topics: Geosciences
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 57 (1985), S. 3857-3859 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Permanent magnet synchronous machines and induction motors are often required to operate on-line starting or inverter-fed systems, which results in nonsinusoidal stator currents. These, in turn, give rise to undesirable harmonics and power losses which degrade motor performance. In this paper a time-domain analysis is presented for evaluating the magnetic field distribution in the two-dimensional cross section of the machine under load conditions. The analysis is applied to a permanent magnet synchronous machine under locked rotor conditions. Although for purposes of this analysis, the iron permeability has been assumed a constant, the method can be easily extended to include iron saturation.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 57 (1985), S. 3866-3868 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Design of modern electrical machinery to operate at high power densities and optimal efficiency requires accurate performance prediction. To accomplish this objective, magnetic field analysis must be performed taking full account of three-dimensional effects and iron saturation. In this paper, a three-dimensional magnetostatic analysis using a hybrid finite-element formulation is presented. The method employs a combined vector and scalar formulation for representing the magnetic field. The analysis developed in the paper is applied to a permanent-magnet synchronous machine for evaluating the field distribution on no-load, in the body of the machine and the end region. Since the operating regime of this particular machine is in the unsaturated region, it was sufficient to implement a finite permeability case. The method described could be easily extended for the full-load case and the nonlinear algorithm implemented.
    Type of Medium: Electronic Resource
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