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Abstract Hydrogenated nitrile butadiene rubber (HNBR) elastomer was thermo-oxidatively aged at different temperatures up to 150 °C. Fourier transform infrared spectroscopy (FTIR), compression stress relaxation (CSR) and international rubber hardness degree (IRHD) microhardness were used to characterise the chemo-mechanical changes of HNBR O-rings during thermo-oxidative ageing. FTIR shows the development of carbonyl, methyl and ester groups but the nitrile content was not affected by ageing. The effect of sample geometry during CSR was investigated. CSR data were converted through integrated kinetic laws. The conversion has proven its sensibility to detect heterogeneous ageing. This was confirmed by the IRHD measure-ments across the section of O-rings. The influence of compression during ageing was assessed through IRHD measurements across the section of compressed and uncom-pressed aged O-rings. The DLO effect was more pronounced in compressed O-rings. By applying the model of Wise et al., theoretical IRHD and oxidation profiles were determined on the basis of IRHD experimental data of compressed O-rings. Good agreements between the experimental and the theoretical IRHD profiles in the core region were obtained. However, near the edge, the theoretical IRHD values were overestimated.
Identification of descriptive parameters of the soil pore structure using experiments and CT data
(2010)
We concentrate on appropriate algorithmic processing of microwave Ground Penetrating Radar (GPR) data obtained from concrete specimens containing tendon ducts below steel reinforcement bars either via simulations or via experiments. The goal is to understand the physical phenomena of electromagnetic wave propagation and scattering in detail in order to optimize imaging algorithms like SAFT (Synthetic Aperture Focusing Technique as the NDT version of SAR) in its 3D diffraction tomographic FT-SAFT formulation (Fourier-Transform-SAFT). Therefore we start with the simulation of a "simple" specimen and switch to a more realistic one in order to check whether simulation and experiment can give comparable results. Basically, this could be confirmed, but, nevertheless, various parametric studies will still have to be performed in the future.
The present study concerns the cleaning of matenats using pulsed laser irradiarton and it summarises the most recent results obtalned by the collaborative research of different European groups, within the kamework of a European program for tralnlng and mobillrv of researchers. A series of pulsed lasers, which emit at various wavelengths (liom UV to IR) wit11 short duration of pulse (few nano-, pico- or fernto-seconds), is used for the removal of metallic, ceramic and organic pollutants kom contaminated solid surfaces of different natures. The scientific results obtained so far are focused on the laser cleaning of silicon wafers from sub-micrometer particles, tile theoretical modelling of particles removal mechanism during dry laser cleaning, the removal of oxide layers from oxidised metals and alloys, as well as on the development of laser imaging as a diagnostrc tool for the estimation of the efficiency of the proposed cleaning technique.