573 research outputs found
Development of a chromium-thoria alloy
Low temperature ductility and high temperature strength of pure chromium and chromium-thoria alloy prepared from vapor deposited powder
Antarctic pack ice algal distribution: Floe-scale spatial variability and predictability from physical parameters
©2017. Commonwealth of Australia. Antarctic pack ice serves as habitat for microalgae which contribute to Southern Ocean primary production and serve as important food source for pelagic herbivores. Ice algal biomass is highly patchy and remains severely undersampled by classical methods such as spatially restricted ice coring surveys. Here we provide an unprecedented view of ice algal biomass distribution, mapped (as chlorophyll a) in a 100 m by 100 m area of a Weddell Sea pack ice floe, using under-ice irradiance measurements taken with an instrumented remotely operated vehicle. We identified significant correlations (p < 0.001) between algal biomass and concomitant in situ surface measurements of snow depth, ice thickness, and estimated sea ice freeboard levels using a statistical model. The model's explanatory power (r2 = 0.30) indicates that these parameters alone may provide a first basis for spatial prediction of ice algal biomass, but parameterization of additional determinants is needed to inform more robust upscaling efforts
Hydrodynamic Coupling of Two Brownian Spheres to a Planar Surface
We describe direct imaging measurements of the collective and relative
diffusion of two colloidal spheres near a flat plate. The bounding surface
modifies the spheres' dynamics, even at separations of tens of radii. This
behavior is captured by a stokeslet analysis of fluid flow driven by the
spheres' and wall's no-slip boundary conditions. In particular, this analysis
reveals surprising asymmetry in the normal modes for pair diffusion near a flat
surface.Comment: 4 pages, 4 figure
Research on Layer Manufacturing Techniques at Fraunhofer
Within the German Fraunhofer-Gesellschaft, the Fraunhofer Alliance Rapid Prototyping
unites the competences of 12 institutes in the field of solid freeform fabrication. Covered
competences are virtual and computer-aided product planning methods and techniques, the
development and integration of materials and processes for different industrial sectors. This
paper presents actual research results on layer manufacturing within the Fraunhofer-
Gesellschaft based on examples from Fraunhofer ILT »Laser Melting - Direct
manufacturing of metal parts with unique properties«, Fraunhofer IFAM »ecoMold - A
novel concept to produce molds for plastic injection molding and pressure die casting« and
Fraunhofer IPT »Quick manufacture, repair and modification of steel molds using
Controlled Metal Build Up (CMB)«.Mechanical Engineerin
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