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  • 11
    Electronic Resource
    Electronic Resource
    Capillary wave gas exchange in the presence of surfactants (1999)
    Springer
    Experiments in fluids 27 (1999), S. 332-338 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  The effect of surfactants on gas exchange across an air/water interface populated with capillary waves, is considered. Experiments were conducted on capillary waves having a wavelength of 2.87 mm in the presence of oleyl alcohol and stearic acid, as well as on surfaces which were surfactant-free. The presence of these surfactants decreased the gas exchange rate by at most a factor of two when the energy delivered to the tank was held constant. Thus, even in the presence of surfactants, pure capillary waves still caused significant gas exchange, indicating that partially damped capillary waves may play an important role in air/sea gas exchange. When the gas exchange coefficient was plotted as a function of mean square slope, the presence of surfactants was found to negligibly affect the gas exchange rate, with the possible exception of the high wave slope regime for stearic acid. This result suggests that it is principally the kinematics of wave motion which accounts for the enhancement of transport due to the capillary waves investigated here. Moreover, these results agree with those obtained from polychromatic, wind-generated waves, suggesting that, for non-breaking waves, knowledge of the statistics of the wave field may be all that is required to parameterize the gas exchange coefficient.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003480050357
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  • 12
    Electronic Resource
    Electronic Resource
    Note on the cancellation of contaminating noise in the measurement of turbulent wall pressure fluctuations (1991)
    Springer
    Experiments in fluids 12 (1991), S. 136-139 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A method is presented for the cancellation of wide band contaminating noise occurring within internal flow configurations such as rectangular channels and pipes. Facility generated noise within these flow systems contaminates the turbulent wall pressure signature at low frequencies thus preventing the possible extraction of useful information. The proposed methodology utilizes the signals from two flush mounted wall pressure transducers. A first estimate for the one-point spectral density is obtained using a least mean square algorithm. A secondary correction to this estimate is obtained by taking advantage of the planar homogeneity of the turbulence. The application of the technique is demonstrated in a fully developed turbulent channel flow for which a more than 40 dB cancellation is obtained at low frequencies. In this low frequency range, the power spectral density is shown to have an approximate quadratic dependence, substantiating past theoretical predictions reported in the literature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00226580
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  • 13
    Electronic Resource
    Electronic Resource
    Turbulent wall pressure fluctuations over wavy surfaces (1990)
    Springer
    Experiments in fluids 10 (1990), S. 33-40 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Measurements of the spectral characteristics of the wall pressure fluctuations produced by a turbulent boundary layer flow over solid sinusoidal surfaces of moderate wave amplitude to wave-length ratios have been obtained. The wave amplitudes were sufficiently small so that the flow remained attatched. The results show that the root mean square pressure level reaches a maximum on the adverse pressure gradient side of the wave at a position somewhat before the trough. Spectral analysis of the pressure fluctuations in narrow frequency bands reveals considerable differences in low and high frequency behavior. At low frequencies, the peak fluctuation amplitude was found at the trough whereas at high frequencies, the peak occurs just after the crest and a minimum is found at the trough. Pressure fluctuations having streamwise correlation lengths on the order of or larger than the wavelength of the surface do not return to their equilibrium (crest) amplitudes as they travel the length of a wave. Pressure fluctuations having streamwise correlation lengths about one order of magnitude less than a wavelength return exactly to their equilibrium amplitudes. Two-point correlation measurements show a decrease in longitudinal coherence on the adverse pressure gradient side of the wave at low frequencies and a considerable increase over a broad frequency range on the positive pressure gradient side. No change is found in the lateral coherence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00187870
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  • 14
    Electronic Resource
    Electronic Resource
    Propagating structures in wall-bounded turbulent flows (1991)
    Springer
    Theoretical and computational fluid dynamics 2 (1991), S. 307-317 
    Details
    ISSN: 1432-2250
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The Karhunen—Loève procedure is used to analyze two turbulent channel flow simulations. In both instances this reveals the presence of propagating plane wave structures in the turbulent flows. These waves appear to play an essential role in the local production of turbulence via bursting or sweeping events. The envelope of the propagating modes propagates with a speed which is equal to the mean velocity at the locus of maximal average Reynolds stress. Despite marked differences between the two flows similar results are obtained from each simulation. This is suggestive of the existence of universal or near universal features in the turbulent boundary layer. An analogy with critical layer mechanisms of transitional flows is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00271470
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  • 15
    Electronic Resource
    Electronic Resource
    Effect of locus of control and consideration of future consequences on time tradeoff utilities for current health (1997)
    Springer
    Quality of life research 6 (1997), S. 0-0 
    Details
    ISSN: 1573-2649
    Keywords: Decision support techniques ; patient preferences ; quality of life
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Comments from subjects undergoing utility assessment suggest that personality traits may affect responses. We sought to describe the association between time-tradeoff utility for current health and measures of two personality traits: (1) perceived control over one's life and (2) concern over immediate vs. future outcomes. One hundred subjects were recruited from the cafeteria of a large tertiary care hospital. Time-tradeoff utilities were assessed for current health relative to perfect health and death. Subjects also completed two previously validated scales, the Locus of Control (LOC), and Consideration of Future Consequences (CFC) instruments. The interview failure rate was less than 3%. The correlation between LOC score and utility for current health was modest (Spearman's ρ =0.196, p=0.071), but increased substantially when subjects unwilling to trade were excluded (Spearman's ρ =0.33, p=0.0043). The CFC scale was weakly correlated with utility for current health (Spearman's ρ =0.12, p=0.2676). The Consideration of Future Consequences scale explains little of the variation in time-tradeoff utilities. In contrast, Locus of Control appears to partially explain the variation in time-tradeoff utilities for current health, even after controlling for health status.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026417528508
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    Paper (German National Licenses)
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  • 16
    Electronic Resource
    Electronic Resource
    40Ar/39Ar ages of detrital white mica from Upper Austroalpine units in the Eastern Alps, Austria: Evidence for Cadomian and contrasting Variscan sources (1997)
    Springer
    Geologische Rundschau 86 (1997), S. 69-80 
    Details
    ISSN: 0016-7835
    Keywords: Keywords Detrital ; White mica ; 40Ar/39Ar ; Eastern Alps ; Palaeozoic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Five detrital white mica concentrates from very low-grade, metaclastic sequences within pre-Variscan basement and post-Variscan cover units of the Upper Austroalpine Nappe Complex (Eastern Alps) have been dated with 40Ar/39Ar incremental heating techniques to constrain the age of tectonothermal events in their respective source areas. Two samples from early Palaeozoic sandstone exposed within the same Alpine nappe record slightly discordant age spectra. The maximum age recorded in one is 562.2±0.7 Ma, whereas the other yielded a 40Ar/39Ar plateau age of 607.3±0.3 Ma. These results indicate a source area affected by Cadomian tectonothermal activity. Three detrital muscovite concentrates from post-Variscan, Late Carboniferous and Permian cover sequences exposed within three different Alpine nappes yielded 40Ar/39Ar plateau ages of 359.6 ± 1.1 Ma, 310.5±1.2 Ma, and 303.3±0.2 Ma. The contrasting detrital white mica ages are interpreted to reflect different source areas. Detrital muscovite from a post-Variscan Carboniferous molasse-type sequence and from a Permian Verrucano-type sequence record ages which indicate “late” Variscan (e.g. 330–300 Ma) metamorphic sources. By contrast, detrital white mica from another Permian Verrucano-type sequence suggests a source area affected by “early” Variscan (e.g. 400–360 Ma) metamorphism. These results help clarify palinspastic relationships and tectonic correlations between pre-Late Carboniferous metamorphic basement sequences and Carboniferous to Permian cover sequences.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005310050122
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  • 17
    Electronic Resource
    Electronic Resource
    Vergleichende Versuche zwischen thixotropen 2-schichtigen und konventionellen 4-schichtigen Korrosionsschutz-Anstrichstoffen in einem Hütten- und Gießereibetrieb (1968)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 19 (1968), S. 595-602 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Comparative tests with thixotropic two-coat and conventional four-coat anticorrosive paints in a smelting plant and foundryThe protection of steel structures by two-coat thixotropic coatings has assumed increasing importance in practice. As there has been, so far, no precise experience about the durability of such coatings in the atmosphere of a smelting plant and foundry, extensive comparative tests have been carried out with two-coat thixotropic and conventional four-coat paint systems. The purpose of the investigations, viz. to collect experience on the broadest possible basis, has been achieved by adopting an elaborate testing arrangement.
    Notes: Der Schutz von Stahlbauwerken durch 2schichtige thixotrope Anstrichsysteme hat in der Praxis steigende Bedeutung erlangt. Da über ihre Haltbarkeit in Hütten- und Gießereiatmosphäre bisher keine exakten Erfahrungen vorlagen, wurden umfangreiche Vergleichsprüfungen zwischen thixotropen 2schichtigen und konventionellen 4schichtigen Anstrichmitteln durchgeführt. Das Ziel der Untersuchung, Erfahrungen auf möglichst breiter Basis zu sammeln, ist durch eine ausgedehnte Versuchsanordnung erreicht worden.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19680190706
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