Sorption of carbon dioxide–methane mixtures

The paper reports the results of experiments concerning the sorption/desorption processes, observed under laboratory conditions, in two types of coal extracted from operational coal-mines in Poland, using CH₄ and CO₂ to observe their relative inter-reaction with the coal samples when introduced in varying proportions and conditions. Numerous studies concerning the sorption/desorption phenomena have described the operational mechanisms and the relationship of mine gases to the organically-created coal-body in mines. The differences in the behaviour of certain gases is twofold: firstly the essentially different characteristics of CO₂ and CH₄, and secondly the structure of the coal-bed itself: its degree of metamorphism and content of macerals. From the results yielded, it was observed that the divergence of the isotherms of sorption of CH₄ and other gases in comparison with the isotherms of sorption of CO₂ and a CO₂/CH₄ mixture differed and that the curve on the sorption isotherm was more clearly distinct after the introduction of CO₂ molecules to the system: coal with a higher degree of metamorphism—CH₄, which is closely related to the rigidity of the structure according to the level of metamorphism. Since coals with higher carbon content exhibit lower molecular bonding than low-carbonised coals, the characteristic feature of the bonds in the first case is their mobility. Knowledge of the physical and chemical properties of hard coals, as well as their interaction with mining gases, is of great use in solving problems concerned with the extraction of methane from mines or its storage in goafs.     

Rapid ground deformation corresponding to a mining-induced seismic event followed by a massive collapse

Natural Hazards - On 17 April 2015, the Wujek/?l?sk underground coal mine in Poland was struck by a strong induced tremor of magnitude M4.0. The event was followed by a massive rock burst...     

Laser-Doppler anemometry and its application to flow investigations related to the environment of vegetation

Accurate measurements in highly turbulent flows, as they occur in nature, require reliable velocity measuring techniques that permit instantaneous velocity components to be locally recorded. Hot-element techniques and optical methods are available for local measurements of instantaneous velocity and the present paper summarizes the advantages and disadvantages of different techniques when applied to flow fields in the environment of vegetation. The paper points out the advantages of laser-Doppler anemometry for velocity measurements in highly turbulent flows under laboratory conditions and stresses the reliability of the technique for measurements in polluted air and water flows. The basic principles of the method are explained and developments are described that have yielded optical anemometer systems for measurements of the magnitudes and signs of the instantaneous velocity components. Both quantities have to be known if accurate measurements of the mean flow properties and turbulence characteristics in flow fields with unknown flow directions are required. Electronic data-processing systems for laser-Doppler anemometer measurements are surveyed, embracing frequency analysers, automatic filter banks, frequency trackers, photon correlators and frequency counters. Photon-correlation and counting techniques are introduced as the methods most likely to be employed for the laser-Doppler anemometer. Laser-Doppler anemometer investigations are described in boundary-layer flows along bean leaves and a metal model of plant leaves. These measurements formed the basis of heat and mass transfer predictions near leaves for a specific leaf position relative to the free stream and with different turbulence properties imposed onto the oncoming flow. These data are presented and discussed in some detail. Measurements are also presented that were carried out to investigate the velocity fields in different flow regimes around a square obstacle in a water flow. These flow properties were needed to understand the different growth rates of sea-weed observed in differing flow regimes.     

Galactic Dynamo and Spiral Arms - 3D MHD Simulations

In the present project we investigate the evolution of a three-dimensional (3D), large-scale galactic magnetic field under the influence of gas flows in spiral arms and in the presence of dynamo action. Our principal goal is to check how the dynamical evolution of gaseous spiral arms affects the global magnetic field structure and to what extent our models could explain the observed spiral patterns of polarization B-vectors in nearby galaxies. A two-step scheme is used: the N-body simulations of a two-component, self-gravitating disk provide the time-dependent velocity fields which are then used as the input to solve the mean-field dynamo equations. We found that the magnetic field is directly influenced by large-scale non-axisymmetric density wave flows yielding the magnetic field locally well-aligned with gaseous spiral arms in a manner similar to that discussed already by Otmianowska-Mazur et al. 1997. However, an additional field amplification, introduced by a non-zero -term in the dynamo equations, is required to cause a systematic increase of magnetic energy density against the diffusive losses. Our simulated magnetic fields are also used to construct the models of a high-frequency (Faraday rotation-free) polarized radio emission accounting for effects of projection and limited resolution, thus suitable for direct comparisons with observations.     

Pure cross-anisotropy for geotechnical elastic potentials

The pure cross-anisotropy is understood as a special scaling of strain (or stress). The scaled tensor is used as an argument in the elastic stiffness (or compliance). Such anisotropy can be overlaid on the top of any elastic stiffness, in particular on one obtained from an elastic potential with its own stress-induced anisotropy. This superposition does not violate the Second Law. The method can be also applied to other functions like plastic potentials or yield surfaces, wherever some cross-anisotropy is desired. The pure cross-anisotropy is described by the sedimentation vector and at most two constants. Scaling with more than two purely anisotropic constants is shown impossible. The formulation was compared with experiments and alternative approaches. Static and dynamic calibration of the pure anisotropy is also discussed. Graphic representation of stiffness with the popular response envelopes requires some enhancement for anisotropy. Several examples are presented. All derivations and examples were accomplished using the algebra program Mathematica.

     

Abnormal features of Macoma balthica (Bivalvia) in the Baltic Sea: alerting symptoms of environmental adversity?

Recent studies of the Baltic clam Macoma balthica (L.) from the southern Baltic (the Gulf of Gdansk) have revealed striking morphological, histological and cytogenetic features. Strong deformation of the shell, including elongation of the posterior end and the appearance of an easily visible flexure in this part, has been recorded. The population contribution of the deformed blunt shelled ("irregular") clams ranged from 0% to 65% and tended to increase with depth. The morphologically "irregular" clams had higher accumulated tissue concentrations of trace metals (As, Ag, Cd, Pb, Cu and Zn), indicating a different metal handling ability. Adverse conditions in deeper water regions of the Gulf (e.g. hypoxia, hydrogen sulphide, elevated bioavailability of contaminants) have been suggested as inducers of the phenotypical changes (morphological deformation) in part of the population and, in parallel, of the specific physiological adaptations that result in higher metal accumulation in the "irregular" clams. Cytogenetic and histological analyses showed the presence of tumours in gill cells and digestive system of the affected clams, the prevalence of disseminated neoplasia ranging from 0% to 94% depending on the site. The disease was manifested by a modified karyotype (i.e. an abnormal number and morphology of chromosomes), a higher activity of nucleolar organizer regions (AgNORs), and tissue lesions (enlarged cells, actively proliferative with pleomorphic nuclei). Bottom sediments showed acute toxicity and have been proposed as a source of an initialising carcinogenic factor. However, none of the ecotoxicological studies provided was successful in the clear demonstration of a single (or multifactorial) agent that can account for the disseminated neoplasia.     

Deep lithospheric structure beneath the Polish part of the East European Craton as a result of magnetotelluric surveys

Studia Geophysica et Geodaetica - A fundamental tectonic boundary between the Precambrian East European Craton (EEC) and the younger Phanerozoic mountain belts of Europe runs through Poland....     

The use of selected research methods to describe the pore space of dolomite from copper ore mine,Poland

Basic knowledge of the characteristics of copper-bearing rock such as dolomite is essential to locate those areas of the deposit which have different structural and textural properties. Those regions can be important in terms of the assessment of the possibilities of gas accumulating in them as well as in terms of gasogeodynamic hazard. To better understand those threats, it is necessary to locate, monitor and analyse those areas in detail. This article characterises the structural and textural parameters of dolomite from the Polkowice–Sieroszowice copper mine in Poland. The study involved five samples from various areas of the mine. A number of research methods were selected. Reflected and transmitted light microscopy (MS), computer microtomography (Micro-CT), gas adsorption porosimetry (LPNA), mercury porosimetry (MIP), helium and quasi-fluid pycnometry (Pycno. He, DryFlo). Each of the methods examined a different scope of the pore size, which enabled to achieve a full view of the porous nature of those rocks. We determined their porosity (open, closed, total), surface area as well as mean size and volume of the pores. Also, we studied the character and the pore size distribution from a few nm to a few mm. Comprehensive dolomite properties analyses showed that these rocks are characterised by high structural variability. They have mesopores and macropores but few micropores. The analyses presented in this paper are determined by a large petrographic diversity of the deposits containing dolomite. This article is an example of a comprehensive approach to the rock analysis in copper ore mines.