The assessment for realistic CO2-adsorption capacities of different rocks is important for understanding the processes associated with CO2 storage. This paper investigates the adsorption characteristics of rocks for CO2 by using a gravimetric method. The measurements were performed at 21oC with pressures from 1 up to 4 MPa. Sandstone (and clay with sand/sandstone) showed the largest adsorption capacity at 21o C. The highest amount of in situ CO2 contents in measured samples was 21.4 kg/t. The CO2 adsorption capacities were lower than past results in different coal samples. The results indicate that adsorption of CO2 into rocks may play an important role in storing CO2 in subsurface rock.
COBISS.SI-ID: 7007097
Site investigation has to be effective and must be carried out in a systematic way. The purpose of this article is to evaluate the number of investigation points, field tests, and laboratory tests for a description of a building site. Such an assessment depends on many parameters based on experiences which cannot be physically evaluated. The guidance on spacing is available from many sources, and such guidance provides a starting point for the extent of investigation. The recommendations were examined and used for building of the model to predict the optimal number of investigation points. Several parameters with the biggest influence on the number of investigation points were considered. The influence of each parameter was determined on the basis of recommendations and engineering judgment. Increments of the minimum number of investigation points for a different building site conditions were used to construct the model with adaptive network fuzzy inference system (ANFIS). The formed ANFIS-SI model was applied on reference cases. There is a good agreement between the model and the reference cases. Additionally, the recommendations for the type and frequency of tests in each stratum are provided to optimize the soil investigation. The ANFIS-SI model, with integrated recommendations, can be used as a systematic decision support tool for engineers to evaluate the number of investigation points for a description of the building site.
COBISS.SI-ID: 17886998
The aluminium alloy 6082 (AA6082) is used as a material for highly loaded construction parts, which means any improvement in its mechanical properties would be an advantage. The majority of approaches employed so far for increasing the mechanical properties only considered a small number of influential parameters and assumed that they were predominately independent of each other. In contrast, in this investigation a simultaneous increase in the yield stress and ductility (elongation) was achieved by considering a larger number of influencing parameters. For this purpose, a database of mechanical properties, process parameters and chemical comp ositions for the hot extruded profiles was collected. Individual and spatial analyses using a CAE neural network were performed to determine the influences of the process parameters and the alloying element s, e.g. Mg, Si, Mn, Fe, Cr and Cu, on the mechanical properties. The results of the analyses provided a new view of their influences, and the possibility to increase the mechanical properties if the process parameters in the relation with the chemical elements are closer to the optimum values. The optimum values of the process parameters and the chemical composition were assessed . In practice, the obtained values for the yield stress and the elong ation confirmed the optimized values for the influential parameters as being correct, since a simultaneous increase of both properties was achieved.
COBISS.SI-ID: 1059934
In order to improve the hot workability of AISI D2 tool-steel ingots during several heats hot-deformation process, laboratory hot-compression tests as well as industrial investigations of the carbides' behaviour were carried out. The conditions that led to the occurrence of undesired, oversized carbides in the matrix were estimated and explained. The area fraction of carbides with respect to their size, their number per mm2 and their sphericity after each hot-deformation cycle were determined. It was found that too high soaking temperature results in an increased size of carbides which decreases hot workability. The results of industrial investigations show that area fraction of carbides after the end of each deformation cycle remains almost constant, but their mean size more than double during deformations in several heats which implies that the final microstructure is not dependent primarily on the last soaking-deformation cycle but depends on entire processing history, i.e. hot workability over several hot-deformation cycles can change considerably from cycle to cycle.
COBISS.SI-ID: 1287775
This paper presents a new, mathematical expression for describing the soil-water characteristic curve (SWCC) over a range of water contents where finegrained soils exhibit plastic properties. The finding that the relationship between the soil suction and the water content can be expressed in terms of the specific surface area of soils was based on experimentally determined relationships between the water content and the soil's specific surface area, as well as between the thickness of the adsorbed water layer on the external surfaces of clay minerals and the quantity of free-pore water for the water content between the liquid and plastic limits. The double-porosity model for the pore-space geometry was considered, as well as that all the water in the clay-aggregates is adsorbed, and that the adsorption mechanism is dominated by the van der Waals forces. The validity and applicability of the proposed equation for the SWCC estimation was verified on three samples in which the SWCC was measured, as well as the specific surface area, the mineralogical and chemical compositions, the grain size distribution, and the Atterberg limits. Despite the fact that good correlations were found between the calculated parts of the SWCC and the measured, the practical applicability of the proposed equation remains problematic due to the values of Hamaker constant, which are not yet well defined for different minerals.
COBISS.SI-ID: 18331670