ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Collection
Keywords
Publisher
Years
  • 1
    facet.materialart.
    Unknown
    Hydric, root and soil cohesions and cohesion from biomass, water and soil loading under various land uses in Laos, Costa Rica and France hillslopes between 2012 and 2015 (2016)
    PANGAEA
    In:  Supplement to: Kim, John H; Fourcaud, Thierry; Jourdan, Christophe; Maeght, Jean-Luc; Mao, Zhun; Metayer, James; Meylan, Louise; Pierret, Alain; Rapidel, Bruno; Roupsard, Olivier; de Rouw, Anneke; Sanchez, Mario Villatoro; Wang, Yan; Stokes, Alexia (2017): Vegetation as a driver of temporal variations in slope stability: The impact of hydrological processes. Geophysical Research Letters, 44(10), 4897-4907, https://doi.org/10.1002/2017GL073174
    Details
    Publication Date: 2023-01-13
    Description: Although vegetation is increasingly used to mitigate landslide risks, how vegetation affects the temporal variability of slope stability is poorly understood, especially in earthquake-prone regions. We combined 3-year long soil moisture monitoring, measurements of soil physical properties and plant functional traits, and numerical modeling to compare slope stability under paired land uses with and without trees in tropical, sub-tropical, and temperate landslide- and earthquake-prone regions. Trees improved stability for 5-12 months per year from drawdown of soil moisture and resulted in less interannual variability in the duration of high-stability periods compared to slopes without trees. Our meta-analysis of published data also showed that slopes with woody vegetation were more stable and less sensitive to climate and soil factors than slopes with herbaceous vegetation. However, estimates of earthquake magnitude necessary to destabilize slopes at our sites suggest that large additional stabilization from trees is necessary for meaningful protection against external triggers.
    Keywords: Chamrousse; Cohesion; DATE/TIME; DEPTH, soil; Event label; Factor of safety; Force; Laos; Llano_Bonito; Load; Vegetation type
    Type: Dataset
    Format: text/tab-separated-values, 44315 data points
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    DATA PANGAEA
  • 2
    facet.materialart.
    Unknown
    Soil inorganic carbon content from great plains of the United States of America and Pampas of Argentina (2020)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Description: This dataset compiles soil carbonate (i.e., soil inorganic carbon or SIC) content (% C) up to 7.8 m depth under natural vegetation (grassland or woodland) and cropland (rain-fed or irrigated). The dataset was collected to examine whether SIC content changes with decades-old agricultural conversion of natural vegetation. SIC represent more than a quarter of the terrestrial carbon pool and are often considered to be relatively stable, with fluxes significant only on geologic timescales. However, given the importance of climatic water balance on SIC accumulation, we tested the hypothesis that increased soil water storage and transport resulting from cultivation may enhance dissolution of SIC, altering their local stock at decadal timescales. We compared SIC storage to 7.3 m depth in eight sites across the Great Plains of the United States of America and the Pampas grasslands of Argentina, each site having paired plots of native vegetation and rain-fed croplands, and half of the sites having additional irrigated cropland plots. We took soil samples down to 8.5 m depth using a direct-push coring rig in the US sites and hand augers at the Argentinean sites. Sampling increments were every 0.3 m in the top 0.61 m of the soil and every 0.61 m thereafter in the US sites, and every 0.2 m to 1 m depth, then every 0.3 m to 4 m depth, and every 0.5 m thereafter in the Argentina sites. Sieved and homogenized soil samples were oven-dried at 60°C for for SIC measurement with a Carlo Erba Elemental Analyzer using the two-temperature combustion method. SIC contents are expressed as %C by weight; we note that this differs from carbonate contents reported by local soil surveys, which are %CaCO3 by weight. Inorganic carbon contents (%C) of the soil and carbonate nodules by depth were multiplied by soil and nodule weights and summed to estimate SIC storage.
    Keywords: Calcium Carbonate; Carbon, inorganic, total; DEPTH, soil; Elemental analyzer, CARLO ERBA; Event label; General-Levalle_soil; Goodwell_soil; Great Plains, United States of America; Hole; LATITUDE; LONGITUDE; Pampas, Argentina; Parera_soil; Quanah_soil; Riesel_soil; Rio-Bamba_soil; San-Angelo_soil; Site; SOIL; soil carbonates; soil inorganic carbon; Soil profile; Tribune_soil; Vegetation type
    Type: Dataset
    Format: text/tab-separated-values, 5256 data points
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    DATA PANGAEA
  • 3
    Electronic Resource
    Electronic Resource
    A linear process in wall-bounded turbulent shear flows (2000)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 12 (2000), S. 1885-1888 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A linear process in wall-bounded turbulent shear flows has been investigated through numerical experiments. It is shown that the linear coupling term, which enhances non-normality of the linearized Navier–Stokes system, plays an important role in fully turbulent—and hence, nonlinear —flows. Near-wall turbulence is shown to decay without the linear coupling term. It is also shown that near-wall turbulence structures are not formed in their proper scales without the nonlinear terms in the Navier–Stokes equations, thus indicating that the formation of the commonly observed near-wall turbulence structures are essentially nonlinear, but the maintenance relies on the linear process. Other implications of the linear process are also discussed. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.870437
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Turbulent boundary layer control utilizing the Lorentz force (2000)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 12 (2000), S. 631-649 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Direct numerical simulations (DNS) of a turbulent channel flow at low Reynolds number (Reτ=100,200,400, where Reτ is the Reynolds number based on the wall-shear velocity and channel half-width) are carried out to examine the effectiveness of using the Lorentz force to reduce skin friction. The Lorentz force is created by embedding electrodes and permanent magnets in the flat surface over which the flow passes. Both open-loop and closed-loop control schemes are examined. For open-loop control, both temporally and spatially oscillating Lorentz forces in the near-wall region are tested. It is found that skin-friction drag can be reduced by approximately 40% if a temporally oscillating spanwise Lorentz force is applied to a Reτ=100 channel flow. However, the power to generate the required Lorentz force is an order of magnitude larger than the power saved due to the reduced drag. Simulations were carried out at higher Reynolds numbers (Reτ=200,400) to determine whether efficiency, defined as the ratio of the power saved to the power used, improves with increasing Reynolds number. We found that the efficiency decreases with increasing Reynolds number. An idealized wall–normal Lorentz force is effected by detecting the near-wall turbulent events responsible for high-skin friction. It is found that the drag can be significantly reduced with a greater efficiency than that produced by the spanwise open-loop control approach. This result suggests that, when employed with a closed-loop control scheme, the Lorentz force might result in a net decrease of power required to propel objects through viscous conducting fluids. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.870270
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    On the effect of riblets in fully developed laminar channel flows (1991)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 3 (1991), S. 1892-1896 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effect of longitudinal riblet surfaces on viscous drag in fully developed laminar channel flows was investigated. Unlike turbulent flows, drag reduction was not obtained in the laminar flows. Results were independent of Reynolds number. Wall-shear rates on most regions of the cross-sectional perimeter of riblets were smaller than that of corresponding plane channel flow even though the net drag was increased.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.857918
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Numerical simulations of turbulent spots in plane Poiseuille and boundary-layer flow (1987)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 30 (1987), S. 2914-2917 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Direct numerical simulations of turbulent spots in plane Poiseuille and boundary-layer flows are performed. Mature, self-similar spots are obtained. The propagation velocities and spreading angles are found to compare well with corresponding experiments. The difference in shape of the two spots is also clearly discernible: the turbulent parts are contained within arrowhead regions that point in opposite directions for the two cases. The wing-tip region of the Poiseuille spot is also found to consist of a large-amplitude semiturbulent wave packet.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.866067
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Steady flow past sudden expansions at large Reynolds number. II. Navier–Stokes solutions for the cascade expansion (1987)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 30 (1987), S. 7-18 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In the steady laminar flow past a sudden expansion at large Reynolds number R, the equations of motion reduce to the boundary-layer equations as R→∞ if the longitudinal length scale of the separated eddy increases linearly and indefinitely with R. In part I of this series [Phys. Fluids 29, 1353 (1986)], several sudden expansion geometries were considered, and in each case, when the inflow was uniform, steady solutions to the boundary-layer equations were found to exist provided that the expansion ratio remained above a critical value where the pressure gradient became singular near the reattachment point of the eddy. These results suggested that for uniform inflows and smaller values of the expansion ratio, the eddy length could not continue to increase linearly with R if the latter were sufficiently large. In the present work a global Newton method was employed to obtain finite-difference solutions to the steady Navier–Stokes equations up to R=1000 for a uniform inflow past a cascade of sudden expansions. The calculations show that for large values of the expansion ratio, the eddy length increases linearly with R, and that the main features of the flow approach those predicted by the boundary-layer solutions, including the existence of large pressure gradients near the reattachment point, as the expansion ratio is reduced toward the critical value. However, for smaller values of the expansion ratio where solutions to the boundary-layer equations could not be found, the steady solutions to the Navier–Stokes equations approach, with increasing R, the limit of an inviscid eddy O(1) in length, with the main features of the flow conforming to the theoretical model of Batchelor [J. Fluid Mech. 1, 388 (1956)] for an inviscid separated eddy behind a bluff body.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.866062
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Application of neural networks to turbulence control for drag reduction (1997)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 9 (1997), S. 1740-1747 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A new adaptive controller based on a neural network was constructed and applied to turbulent channel flow for drag reduction. A simple control network, which employs blowing and suction at the wall based only on the wall-shear stresses in the spanwise direction, was shown to reduce the skin friction by as much as 20% in direct numerical simulations of a low-Reynolds number turbulent channel flow. Also, a stable pattern was observed in the distribution of weights associated with the neural network. This allowed us to derive a simple control scheme that produced the same amount of drag reduction. This simple control scheme generates optimum wall blowing and suction proportional to a local sum of the wall-shear stress in the spanwise direction. The distribution of corresponding weights is simple and localized, thus making real implementation relatively easy. Turbulence characteristics and relevant practical issues are also discussed. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.869290
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Propagation velocity of perturbations in turbulent channel flow (1993)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 5 (1993), S. 695-706 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A database obtained from direct numerical simulation of a turbulent channel flow is analyzed to extract the streamwise component of the propagation velocity V of velocity, vorticity, and pressure fluctuations from their space-time correlations. A surprising result is that V is approximately the same as the local mean velocity for most of the channel, except for the near-wall region. For y+≤15, V is virtually constant, implying that perturbations of all flow variables propagate like waves near the wall. In this region, V is 55% of the centerline velocity Uc for velocity and vorticity perturbations and 75% of Uc for pressure perturbations. This is equal to U at y+=15 for velocity and vorticity perturbations, and equal to U at y+=20 for pressure perturbations, indicating that the dynamics of the near-wall turbulence is controlled by turbulence structures present near y+(approximately-equal-to)15–20. Scale dependence of V is also examined by analyzing the bandpass-filtered flow fields. This paper contains comprehensive documentation on the propagation velocities, which should prove useful in the evaluation of Taylor's hypothesis. An attempt has been made to explain some of the data in terms of the current understanding of organized structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.858653
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    On the shape and dynamics of wall structures in turbulent channel flow (1989)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 1 (1989), S. 764-766 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Turbulence-producing events in turbulent channel flow were found to be predominantly associated with asymmetric vortical structures rather than pairs of counter-rotating structures. An asymmetry-preserving averaging scheme was devised, allowing a picture of the "average'' structure that more closely resembles the instantaneous one to be obtained. In addition, these structures were found to persist for long distances with little change while convecting downstream.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.857373
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...