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Number of results: 623
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Abstract

A numerical algorithm is presented for the filling process of a cylindrical column with equilateral cylinders. The process is based on simplified mechanics - the elements are added one by one until the mechanical equilibrium is reached. The final structure is examined with respect to the global and local porosity distribution. Oscillating radial porosity profile is obtained in accordance with experimental data.
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Abstract

The paper presents a detailed analysis of the material damaging process due to lowcycle fatigue and subsequent crack growth under thermal shocks and high pressure. Finite Element Method (FEM) model of a high pressure (HP) by-pass valve body and a steam turbine rotor shaft (used in a coal power plant) is presented. The main damaging factor in both cases is fatigue due to cycles of rapid temperature changes. The crack initiation, occurring at a relatively low number of load cycles, depends on alternating or alternating-incremental changes in plastic strains. The crack propagation is determined by the classic fracture mechanics, based on finite element models and the most dangerous case of brittle fracture. This example shows the adaptation of the structure to work in the ultimate conditions of high pressure, thermal shocks and cracking.
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Abstract

The paper presents a thermodynamic optimization of supercritical coal fired power plant. The aim of the study was to optimize part of the thermal cycle consisted of high-pressure turbine and two chosen highpressure feed water heaters. Calculations were carried out using IPSEpro software combined with MATLAB, where thermal efficiency and gross power generation efficiency were chosen as objective functions. It was shown that the optimization with newly developed framework is sufficiently precise and its main advantage is the reduction of computation time on comparison to the classical method. The calculations have shown the tendency of the increase in efficiency, with the rise of a number of function variables.
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Abstract

Miarą sukcesu rozwojowego współczesnych regionów i zarazem czynnikiem podtrzymującym trwałość tego sukcesu jest przede wszystkim jakość życia mieszkańców. Według definicji Rady Europy (A new strategy for Social Cohesion, 2004, s. 3) spójność społeczna to zdolność terytorialnych społeczności do zapewnienia dobrobytu wszystkim swoim członkom, zmniejszania rozwarstwień społecznych i unikania polaryzacji. W ocenie spójności społecznej regionu dolnośląskiego w przekroju powiatów w latach 2005–2015 uwzględniono zmienne z następujących dziedzin: dochody i aktywność ekonomiczna ludności, warunki mieszkaniowe ludności, dostępność usług i przestrzeni publicznej. Do pomiaru i oceny zmian poziomu spójności społecznej województwa dolnośląskiego w przekroju powiatów w latach 2005–2015 zastosowano odległość GDM1 oraz miernik Theila.
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Abstract

This paper describes the spatial differentiation of topoclimatic conditions in the vicinity of the Arctowski Station (King George Island, Antarctica) during the summer season of the 2006/2007. The measurement stations were located in the Point Thomas oasis as well as on the Ecology Glacier and Warszawa Icefield. The paper analyses meteorological elements such as air temperature, air humidity (eight sites) and wind direction and velocity (three sites). Significant topoclimatic diversities resulting from denivelation, exposure, ground properties and local air circulation were recorded in the study area.
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Abstract

The buoyant hypopycnal flow of brackish water and suspended sediment transport and settling were studied in two sub-polar fjords: the glacial Kongsfjörden and the outwash (non-glacial contact) Adventfjörden, Svalbard . The data presented indicates faster water mixing on the tidal flat in comparison to the englacial runoff, which leads to faster horizontal density gradients decreases in the non-glaciated fjord. The fast settling of particles in the narrow zone of the steep slope at the edge of the tidal flat leads to the removal of 25% of the surface suspended sediment. The rapid settling is due to increasing salinity, decreasing velocity, and flocculation of fine particles. The fast settling of suspended particulate matter (SPM) in the tidal flat area causes sediment redeposition and resuspension followed by sediment transport along the bottom with hyperpycnal flows. This leads to grain sorting in the fjord head. In contrast, at the glacier front, SPM is transported farther into the fjord, where tidal pumping and water mixing lead to the removal of 71% of total SPM. The fjords investigated represent two different sedimentological regimes. In the glaciated Kongsfjörden, the buoyant hypopycnal flow of brackish water is the main sediment transporting factor. In the non-glacial Adventfjörden, hyperpycnal flows transport sediment along the bottom.
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Abstract

An analysis of seismic shocks from the Heer Land and the Nordaustlandet was made (shocks recorded by the Hornsund seismological station). Kinematic models and synthetic seismograms were constructed. A system of horizontal discontinuities located in the upper mantle was assumed. A good agreement between observational data from the seismograms and theoretical results was obtained.
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Abstract

Studies on the thermics, humidity and refreezing rate of two types of periglacial soils of the marine lowlands of the Hornsund area (SW Spitsbergen) were carried out during spring ablation of the snow cover (1.06.—30.06.1987). Structural soil and peat soil (moss community) were chosen. The soils were studied in places almost completely devoid of the snow cover. A considerable differentiation of temperature in vertical profile and of humidity of surface layer in both soils were found. The dynamics of ground water table and the course and depth of spring refreezing of both soils were also different. The differences reflect the different origin of soils and consequently, their different grain-size distribution, physical properties and morphology of both types of soils as well as their water balance.
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Abstract

Research in Hornsund (SW Spitsbergen) aimed to determine time distribution of heat flux in various soils of Arctic periglacial zone in spring and summer. Typical soils were analysed: tundra gleyey cryogenic soil (Pergelic Cryaquent), tundra peaty soil (Pergelic Histosot) and arctic desert soil (Pergelic Cryorthent). Research sites were located in low plains not covered with ice, near a sea, at 7—13 m a.s.l. Heat flux in soils was measured and recorded automatically every 60 s throughout a whole observation period and concurrently at three sites. In spring and summer intensive heat accumulation was observed in all examined soils. Independently on the weather, a cryogenic gleyey soil received greatest heat throughout a day. Environmental conditions have distinct influence on heat resources in soils.
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Abstract

Hot point drills were carried through in the Hans Glacier (Spitsbergen). For that purpose a non-cored hot point drill of 700 wattage was constructed. It was used among others for installing the ablation-movement stakes, for hydrological observations and in the boreholes an ice temperature was controlled.
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Abstract

Several conclusions and recommendations concerning sediment trap geometry, the technique of their deployment and interpretation of measurements results are described in this paper. Only cylindrical sediment traps are able to cope with the diverse and dynamic environment of glaciated fjords. The relation between different trap parameters shows the optimal proportion of cylinder diameter as being between 6 and 10 cm and ratio length/diameter not less than 7/1. During the peak of the melting season in Kongsfjorden (Spitsbergen) the rate of sedimentation of total matter reaches over 900 g m–2 d–1 and the velocity of brackish water current can reach 80 cm s–1 on the surface. Owing to the high productivity of Arctic fiords and large concentration of suspended mineral matter it is possible to collect of large samples in a short time, therefore prevention of sediment traps by swimmers is not necessary.
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Abstract

The paper presents the trends of air temperature of the Antarctic. In its elaboration 21 stations were taken into consideration carrying out temperature measurements in the years 1958–2000, and 34 stations in the years 1981–2000. After checking the homogeneity of the series by the Alexandersson’s (1986) test we found that at 16 stations the homogeneity has been broken. On the basis of the corrected measurement series we have determined the trends in air temperature. In the period 1958–2000 statistically significant (on 0.95 significance level) temperature increases occurred on the western coast of the Antarctic Peninsula (for example Faraday 0.67°C/10 years) and at the Belgrano and McMurdo stations. The greatest temperature rise was noted on the Antarctic Peninsula during the autumn-winter period. On the South Pole a negative trend in air temperature (–0.21°C) occurred, especially in the summer season. During recent years (1981-2000) significant changes took place in the air temperature tendencies in the Antarctic. In many regions of the Antarctic cooling began and on the cost of East Antarctica the temperature decreased by –0.82°C/10 years (Casey). In the interior of the continent also lower and lower temperatures occurred (Amundsen-Scott –0.42°C/10 years, Dome C –0.71°C/10 years). The coast of the Weddell Sea is getting colder (Halley –1.13°C/10 years, Larsen Ice –0.89°C/10 years). An increase in temperature was observed in the interior of West Antarctica (Byrd 0.37°C/10 years). The warming rate of the climate became weaker on the Antarctic Peninsula (Faraday 0.56°C/10 years). The largest temperature changes occurred in the autumn-winter season when in the Antarctic Peninsula region the temperature increased, while in the interior and at the coast of East Antarctica temperatures fell considerably.
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Abstract

To retain our cultural identity in the modern world and sensibly think about the future, we need to thoroughly study the past,” says Prof. Marek Figlerowicz from the PAS Institute of Bioorganic Chemistry, who leads the project “The Dynasty and Society of Piast-Era Poland in the Light of Integrated Historical, Anthropological, and Genomic Research.”
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Keywords shale gas

Abstract

Shale gas mining is mainly viewed as an industrial and economic issue. But we can also look at it from the scientific perspective. Why should we?
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Abstract

The article deals with the patterns of segmental adaptation of Polish voiceless affricates in initial and fi nal CC (consonant + consonant) clusters by native speakers of English. The data have been collected in an online loanword adaptation experiment in which 30 native speakers of Southern British English reproduced Polish words containing such sequences. The major problem posed by the data is the divergent adaptation of the post-alveolar /͡tʂ/ vs. the pre-palatal /͡tɕ/, with the former substituted mainly with the coronal plosive [t] and the latter realised as the palato-alveolar affricate [͡tʃ]. It is argued that these patterns of nativisation are due to the highlyranked IDENT-IO[dist] constraint, which militates against the modifi cation in the value of the feature [distributed]. Furthermore, it is demonstrated that the experimental results provide evidence in favour of the fundamental assumptions underlying the phonological approach to loan assimilation, namely the phonological input view as well as the faithful perception view.
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Abstract

Switched reluctance motors (SRMs) are still under development to maximise their already proven usefulness.Amagnetic circuit of theSRMcan be made of soft magnetic composites (SMCs). The SMCs are composed of iron powder with dielectric and have a lot of advantages in comparison to commonly used electrical steel. The paper deals with the modelling and analysis of theSRMproduced by Emerson Electric Co. forwashing machines. Numerical calculations and modelling were done using the FEMM 4.2 program. Magnetic flux densities and magnetic flux lines were calculated, as well as electromagnetic torque and inductance for changing the position of a stator to a rotor. The obtained results were compared with other measurement results and are quite similar. The developed numerical model will be used for the project of a motor with an SMC magnetic circuit.
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