Malte A. Peter

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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 hydroxide, other constituents such as calcium silicates or calcium-silcate hydrates in(More)
We study the convergence of an adaptive Interior Penalty Discontinuous Galerkin (IPDG) method for a 2D model second order elliptic boundary value problem. Based on a residualtype a posteriori error estimator, we prove that after each refinement step of the adaptive scheme we achieve a guaranteed reduction of the global discretization error in the mesh(More)
A method is proposed to determine the modal spectra of waves supported by arrays, which are composed of multiple rows of scatterers randomly disordered around an underlying periodic configuration. The method is applied to the canonical problem of arrays of identical small acoustically-soft circular cylinders, and disorder in the location of the rows. Two(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 nondimensionalisation is introduced to pay attention to the different characteristic time(More)
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 relatively high CO2-concentrations and a fixed relative humidity. No general agreement exists on whether and how the results of these experiments can be(More)
This article describes a survey feedback intervention in which staff nurses were surveyed about various job characteristics, job satisfaction, and intent to remain in the organization. Nurse managers received the feedback through graphs and a workshop. A year later the same survey was conducted, and the results were compared with preintervention data. Of(More)