Sebastian Meier

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We discuss the fast-reaction limit of a two-scale reaction-diffusion model. We point out that if the reaction constant a explodes to infinity, then a two-scale PDEs system with free boundary at the micro cell is obtained. The aim of this note is to answer the question: Can the same two-scale free-boundary problem be obtained if we first pass to the(More)
Transport and reaction of carbon dioxide with alkaline species in concrete is modelled by a closed system of ordinary and partial differential equations. Varying porosity and varying external exposure as well as nonlinear reaction rates are taken into account. Proper nondi-mensionalisation is introduced to pay attention to the different characteristic time(More)
We suggest and demonstrate a novel platform for the study of tunable nonlinear light propagation in two-dimensional discrete systems, based on photonic crystal fibers filled with high index nonlinear liquids. Using the infiltrated cladding region of a photonic crystal fiber as a nonlin-ear waveguide array, we experimentally demonstrate highly tunable beam(More)
Concrete carbonation, i.e. the reaction of alkaline species (inside the concrete) with atmospheric carbon dioxide, is one of the major physicochemical processes compromising the service life of concrete structures. While the main carbonation reaction is that of calcium hy-droxide, other constituents such as calcium silicates or calcium-silcate hydrates in(More)
We investigate a reaction–diffusion process in a two-phase medium with microscopic length scale ε. The diffusion coefficients in the two phases are highly different (d 1 /D = ε 2) and the reaction constant k is large. First, the homogenisation limit ε → 0 is taken, which leads to a two-scale model. Afterwards, we pass to the fast-reaction limit k → ∞ and(More)
Oxide-derived copper (OD-Cu) electrodes exhibit unprecedented CO reduction performance towards liquid fuels, producing ethanol and acetate with >50% Faradaic efficiency at -0.3 V (vs. RHE). By using static headspace-gas chromatography for liquid phase analysis, we identify acetaldehyde as a minor product and key intermediate in the electroreduction of CO to(More)
This thesis consists of two independent studies employing chemometrics and instrumental neutron activation analysis (INAA): cloudwater and rainwater studies at Mt. Washington, New Hampshire and wet deposition studies at Moss Lake and Willsboro in the Adirondack region, New York. Three major factors (a background, an acidity, and a crustal factor) were(More)
Fachbereich 3 – Mathematik und Informatik A note on limitations of the use of accelerated concrete-carbonation tests for service-life predictions Abstract Concrete carbonation is a process that can limit the lifetime of reinforced concrete structures. The resistance of concrete samples to carbonation is usually determined by accelerated tests under(More)
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