An Iterative Method for Calculation of Wind Profiles at the Mesoscale and Microscale

Boundary-Layer Meteorology - Space–time correlations are fundamental to statistical theories and turbulence modelling. However, experimental studies of space–time correlations are often...     

Microstructure measures and the minimum size of a representative volume element: 2D numerical study

In the paper, a numerical study of the size of a representative volume element (RVE) for both the heat flow as well as the linear elasticity problems is presented. A particular two-phase random microstructure is studied and the method is applied to the digital image of reconstructed 2D realization of random media. The minimum size of RVE is determined by the investigation of the convergence of apparent properties as the size of RVE is increasing. Then, two estimates of the minimum RVE size are proposed and it is shown that the estimates are in a good agreement with the results determined by the investigation of the convergence of apparent properties. The minimum size of RVE can be successfully predicted based only on the microstructure morphology. The statistical measures used in this work are: the two-point probability and the linealpath functions.     

High-resolution computed microtomography for the characterization of a diffusion tensor imaging phantom

This paper addresses the issue of the quantitative characterization of the structure of the calibration model (phantom) for b-matrix spatial distribution diffusion tensor imaging (BSD-DTI) scanners. The aim of this study was to verify manufacturing assumptions of the structure of materials, since phantoms are used for BSD-DTI calibration directly after manufacturing. Visualization of the phantoms’ structure was achieved through optical microscopy and high-resolution computed microtomography (µCT). Using µCT images, a numerical model of the materials structure was developed for further quantitative analysis. 3D image characterization was performed to determine crucial structural parameters of the phantom: porosity, uniformity and distribution of equivalent diameter of capillary bundles. Additionally calculations of hypothetical flow streamlines were also performed based on the numerical model that was developed. The results obtained in this study can be used in the calibration of DTI-BST measurements. However, it was found that the structure of the phantom exhibits flaws and discrepancies from the assumed geometry which might affect BSD-DTI calibration.     

Application of the Unified Stream Assessment Method to Determine the Direction of Revitalization of Heavily Transformed Urban Rivers

Water Resources - The issues related to the assessment of the hydro morphological status of urban rivers in order to identify the revitalisation actions possible to be carried out, has been...     

Anisotropy of magnetic susceptibility as an indicator for palaeocurrent analysis in folded turbidites (Outer Western Carpathians,Poland)

The anisotropy of magnetic susceptibility is a well-known geological proxy in revealing the directional tectonic and sedimentological features of rocks, although it can be ambiguous in situations where these two factors co-occur. This paper demonstrates the usefulness of the anisotropy of magnetic susceptibility in determining palaeotransport directions in turbiditic rocks that underwent subsequent thrusting and folding. This study demonstrates that the magnetic lineation is largely unsuitable as a palaeocurrent direction proxy, and suggests that the imbrication of magnetic foliation is better in such cases. Moreover, the anisotropy of magnetic susceptibility results were analyzed in reference to a joint and fold study within the framework of the regional structural geology. Magnetic fabric investigations were conducted in the eastern part of the Outer Western Carpathians (south-east Poland). During the study, a total of 191 oriented palaeomagnetic samples were collected from three outcrops (Nasiczne, Dwernik and Hoczew) in the Krosno Beds, Silesian Unit. For the purpose of sedimentological analysis, 121 m of turbidite successions were documented and 126 directional sedimentary structures were measured. The magnetic anisotropy of sandstones revealed typical sedimentary fabrics, often overprinted by variably intense tectonic deformation. Oblate susceptibility ellipsoids from Nasiczne showed tilt coherent with the palaeoflow direction, whereas the rocks from Dwernik and Hoczew contained triaxial magnetic fabric developed during compressional palaeostress. This paper suggests that medium-grained and coarse-grained sandstones, preferably with high mica content, are the most suitable for palaeotransport reconstructions among the studied lithologies.     

Detection of the historical Askja ad 1875 and modern Icelandic cryptotephras in varved lake sediments – results from a first systematic search in northern Poland

Volcanic ash can disperse thousands of kilometres from the source volcano and provide valuable chronostratigraphic markers for palaeoclimate studies. We present new cryptotephra findings of historical and modern Icelandic eruptions in annually laminated lacustrine sediment records from several sites within a 570 km SW–NE transect across northern Poland. Sediments from the two lakes Wąsoskie and Szurpiły contain glass shards originating from the Plinian Askja ad 1875 eruption and showing bimodal, rhyolitic and dacitic affinities. A further cryptotephra finding in Lake Lubińskie suggests a potential origin from the Hekla ad 1845 eruption. These new findings extend the tephra dispersal map towards the south-east and provide valuable isochrons for the synchronisation of palaeoclimate proxy data at the termination of the Little Ice Age in central eastern Europe. Very low glass concentrations of modern cryptotephra in Lake Wąsoskie were potentially correlated with the Eyjafjallajökull ad 2010 eruption. Further findings in the uppermost sediments of lakes Szurpiły and Żabińskie in north-eastern Poland tentatively suggest other sources from either the Hekla and/or Kamchatkan volcanoes.     

Bacterial consortium and axenic cultures isolated from activated sewage sludge for biodegradation of imidazolium-based ionic liquid

Extensive research and increasing number of potential industrial applications made ionic liquids (ILs) important materials in design of new, cleaner technologies. Together with the technological applicability, the environmental fate of these chemicals is considered and significant efforts are being made in designing strategies to mitigate their potential negative impacts. Many ILs are proven to be poorly biodegradable and relatively toxic. Bioaugmentation is known as one of the ways of enhancing the microbial capacity to degrade xenobiotics by addition of specialized strains. The aim of current work was to select microbial species that could be used for bioaugmentation in order to enhance biodegradation of ILs in the environment. We subjected activated sewage sludge to the selective pressure of 1-methyl-3-octylimidazolium chloride ([OMIM][Cl]) and isolated nine strains of bacteria which were able to prevail in these conditions. Subsequently, we utilized axenic cultures (pure cultures) of these bacteria as well as mixed consortium to degrade this IL. In addition, we performed growth inhibition tests and found that bacteria were able to grow in 2 mM, but not in 20 mM solutions of [OMIM][Cl]. The biodegradation conducted by the isolated consortium was higher than conducted by the activated sewage sludge when normalized by the cell density, which indicates that the isolated strains seem specifically suited to degrade the IL.     

On the mean free path of solar cosmic rays – I. Protons

The spatial transport of charged particles in the presence of pure slab Alfvén waves, pure isotropic magnetosonic waves and their mixture is considered using Monte Carlo particle simulations. We show that the mean free path of solar cosmic ray protons strongly depends on the assumed spectrum and amplitude of MHD turbulence but much less on the type of the considered waves. It is demonstrated that, for realistic solar wind parameters, the presented wide range wave spectrum models can reproduce the observed mean free path in a particular SEP event but not in a wide range of rigidity characterized by the Palmer's `consensus'.     

Results of statistical analysis of primary components concentrations in bulk chemical composition of ordinary chondrite groups

We used two different methods of statistical analysis—cluster analysis and principal component analysis—to analyze the concentrations of principal chemical components (Si, Mg, Ca, Fe, Ni) and Co in ordinary chondrites. The analysis is based predominantly on published data (metadata). In total, chemical composition data from 646 ordinary chondrites were used in the statistical analysis. The aim of this analysis was to establish whether it would be possible or not to distinguish H, L, and LL chondrites based on the concentrations of major elements and Co in their bulk chemical compositions. It was also important to determine what conclusions such an analysis could enable to draw about matter differentiation in the formation environments of primordial parent bodies of particular ordinary chondrite groups (H, L, and LL). Another aim of the statistical analysis was to determine whether the distribution of Fe and Ni (with Co admixtures) is independent of petrographic types within particular groups of chondrites. This is of crucial importance for determining the distribution of FeNi(Co) ore occurrences in potential extraterrestrial deposits on modern asteroids—the sources of ordinary chondrites. The obtained results of statistical analyses confirmed that a clear-cut distinction between particular groups of ordinary chondrites is only possible for group H, while distinguishing L chondrites from LL chondrites is not always obvious. The results of the statistical analyses relating to the question of the possible existence of several primordial parent bodies (formation environments) of each group of ordinary chondrites are consistent with the results of contemporary astronomical spectroscopy research. What is particularly interesting is obtaining indications of the existence of common formation environments of the matter of L and LL chondrites, possibly on a few primordial parent bodies. The statistical analyses indicate that there is no correlation between the concentration of principal chemical components and the petrographic type of ordinary chondrites. This proves homogenous distributions of these elements within the parent bodies of each group of ordinary chondrites. Hence, the distribution of these elements in individual present-day asteroids is also homogenous.