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11.
Expanded art for a social technology : counting craters in dialog between human and machine
2020, radio or television broadcast, podcast, interview, press conference

Keywords: expanded installations, mixed media, internet, privacy, decentralized infrastructures, workshop method, transgenerational, personal data
Published in RUNG: 09.02.2021; Views: 2151; Downloads: 20
URL Link to full text

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Modelling of Macrosegregation of a Low-Frequency Electromagnetic Direct Chill Casting by a Meshless Method
Vanja Hatić, 2019, doctoral dissertation

Abstract: The main aim of the dissertation is to develop a meshless model that describes the solidification and macrosegregation phenomena during the direct chill casting (DCC) of aluminium alloys under the influence of a low-frequency electromagnetic field. Macrosegregation is an undesired consequence of alloy solidification. It represents one of the major casting defects and substantially reduces the quality of the finished product. On the other hand, low-frequency electromagnetic casting (LFEC) is a process that promises to increase greatly the product quality, including the reduction of macrosegregation. The modelling of both processes is of tremendous importance to the metallurgical industry, due to the high costs of experiments during production. The volume-averaging formulation is used for the modelling of the solid-liquid interaction. The conservation equations for mass, energy, momentum, and species are used to model the solidification of aluminium-alloy billets in axysimmetry. The electromagnetic-induction equation is coupled with the melt flow. It is used to calculate the magnetic vector potential and the Lorentz force. The Lorentz force is time-averaged and included in the momentum-conservation equation, which intensifies the melt flow. The effect of Joule heating is neglected in the energy conservation due to its insignificant contribution. The semi-continuous casting process is modelled with the Eulerian approach. This implies that the global computational domain is fixed in space. The inflow of the liquid melt is assumed at the top boundary and the outflow of the solid metal is assumed at the bottom. It is assumed that the whole mushy area is a rigid porous media, which is modelled with the Darcy law. The Kozeny-Carman relation is used for the permeability definition. The incompressible mass conservation is ensured by the pressure correction, which is performed with the fractional step method. The conservation equations and the induction equation are posed in the cylindrical coordinate system. A linearised eutectic binary phase diagram is used to predict the solute redistribution in the solid and liquid phases. The micro model uses the lever rule to determine the temperature and the liquid fraction field from the transport equations. The partial differential equations are solved with the meshless-diffuse-approximate method (DAM). The DAM uses weighted least squares to determine a locally smooth approximation from a discrete set of data. The second-order polynomials are used as the trial functions, while the Gaussian function is used as the weight function. The method is localised by defining a smooth approximation for each computational node separately. This is performed by associating each node with a unique local neighbourhood, which is used for the minimisation. There are 14 nodes included in the local subdomains for the DCC and LFEC simulations. The stability of the advective term is achieved with a shift of the Gaussian weight in the upwind direction. This approach is called the adaptive upwind weight function and is used in the DAM for the first time. The Explicit-Euler scheme is used for temporal discretisation. The use of a meshless method and the automatic node-arrangement generation makes it possible to investigate the complicated flow structures, which are formed in geometrically complex inflow conditions in a straightforward way. A realistic inflow geometry and mould can therefore be included in the model. The number of computational nodes is increased in the mushy zone and decreased in the solid phase, due to the optimisation of the computational time and memory. The computational node arrangement is automatically adapted with time, as the position of the mushy zone is changed in shape and position.
Keywords: low-frequency electromagnetic casting, direct chill casting, macrosegregation, electromagnetic stirring, aluminium alloys, meshless methods, diffuse-approximate method, multiphysics model, solidification
Published in RUNG: 25.04.2019; Views: 3773; Downloads: 148
.pdf Full text (28,80 MB)

14.
Synthesis of a Cu/ZnO Nanocomposite by Electroless Plating for the Catalytic Conversion of CO2 to Methanol
Maja Pori, Iztok Arčon, Damjan Lašič Jurković, Marjan Marinšek, Goran Dražić, Blaž Likozar, Zorica Crnjak Orel, 2019, original scientific article

Abstract: The process of methanol synthesis based on the hydrogenation of CO2 was investigated over binary Cu/ZnO catalyst materials, prepared by applying a novel electroless plating fabrication method. The activity of the produced catalytic samples was determined at temperature range between 200 and 300 °C and the feedstock conversion data were supplemented with a detailed microstructure analysis using high-resolution transmission electron microscopy (HRTEM), X-ray powder diffraction (XRD) and Cu and Zn K-edge, X-ray absorption near-edge structure (XANES) measurements and extended X-ray absorption fine-structure (EXAFS) measurements. It was confirmed that the disorder in the Cu crystallites created unique geometrical situations, which acted as the additional reactive centres for the adsorption of the reactant molecule species. Copper and zinc structural synergy (spill-over) was also demonstrated as being crucial for the carbon dioxide’s activation. EXAFS and XANES results provide strong evidence for surface alloying between copper and zinc and thus the present results demonstrate new approach applicable for explaining metal–support interactions.
Keywords: EXAFS, CuZn alloy, Spillover mechanism, CO2 valorization, Electroless deposition method, Heterogeneous catalysis
Published in RUNG: 12.04.2019; Views: 3485; Downloads: 0
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15.
A NEW TOOL TO EVALUATE CORTISOL CONCENTRATIONS IN ANIMAL HAIR
Antonella Comin, Tanja Peric, Mara Colzani, Francesco De Vecchi, Cristina Bergamin, Alberto Prandi, 2018, published scientific conference contribution abstract

Abstract: The study of cortisol in hair requires the use of a highly sensitive assay. To date, hair cortisol concentrations (HCC) have been evaluated with different analytical methods as Radio Immune Assay (RIA), Enzyme Immunossay (EIA), Enzyme Linked Immunosorbent Assay (ELISA), ChemiLuminescent Immunoassay (CLIA) and High Performance Liquid Chromatography with Mass Spectrometry (HPLC/MS) or Liquid Chromatography with Tandem Mass Spectrometry (LC-MS/MS). Amplified luminescent proximity homogeneous assay (AlphaLISA) is an ELISA-like, nonradioactive technology first reported in 1994 [1]. This technology allows the quantitative detection of molecules of interest in a light-induced chemiluminescence immunoassay using a microplate without wash step. The aim of the study was to compare RIA with AlphaLISA method and examine the sensitivity in evaluating cortisol concentrations in animal hair of the Cortisol AlphaLISA kit (PerkinElmer, USA), originally suggested for the analysis of buffer and serum samples. The study has been carried out on 4 samples of calf, 4 samples of foal and 8 samples of sheep hair. After washing with isopropanol, two extracts were obtained from each hair sample. One extract has been evaluated for HCC by RIA as previously described [2,3]. The second extract has been reconstituted with the buffer provided by the Cortisol AlphaLISA Kit and HCC evaluated by the use of this commercially available kit. The preliminary results indicate that the Cortisol AlphaLISA Kit is capable to detect cortisol also in hair samples with high sensitivity, with a detection limit of 17 pg/ml. Intra- and inter-assay coefficients of variation (CVs) were 4.0% and 9.0%, respectively. Cortisol concentrations ranged between 1.31 and 16.94 pg/mg, 6.30 and 57.65 pg/mg, and 2.16 and 45.08 in calf, foal and sheep hair, respectively. The HCC obtained by Cortisol AlphaLISA Kit and RIA showed a good correlation (r=0.79, p<0.01). Considering the possibility to use a low amount of extracted sample, its no-washing procedure and the performances showed, we can conclude that the Cortisol AlphaLISA Kit can be considered an excellent tool to evaluate cortisol concentrations also in hair derived from animal species.
Keywords: hair, cortisol, analyses, method, AlphaLISA, Amplified luminescent proximity homogeneous assay
Published in RUNG: 09.04.2019; Views: 3307; Downloads: 0
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Discontinuous Galerkin method for linear free-surface gravity waves
J. J. W. van der Vegt, Satyendra Tomar, 2005, original scientific article

Keywords: discontinuous Galerkin method, gravity waves, elliptic partial differential equations
Published in RUNG: 13.11.2018; Views: 2960; Downloads: 0
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An implicit discontinuous Galerkin finite element method for water waves
J. J. W. van der Vegt, Satyendra Tomar, 2004, published scientific conference contribution

Keywords: discontinuous Galerkin method, water waves, elliptic partial differential equations
Published in RUNG: 13.11.2018; Views: 3104; Downloads: 0
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