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Number of results: 7
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Abstract

The term Pakoszówka-Bessów type pottery is used to describe a specific kind of wheelmade pottery with easily abradable surfaces mostly dated to the 3rd century AD. Site 3 in Bessów, Bochnia Commune, Lesser Poland, is located in the dense Przeworsk culture settlement micro-region occupying the right bank of the lower reaches of the Raba River. The most characteristic feature of locally produced artefacts from Bessów, and to a lesser extent from other sites in the region, is the presence of enormous amounts of this pottery. The aim of laboratory analyses carried out on Pakoszówka-Bessów type pottery from Bessów was to verify the hypothesis that abradability of sherd surfaces is attributable to the alteration effect.
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Abstract

The paper presents Lusatian culture bronze artefacts recovered in the Orava region in northern Slovakia, which allows for tracing connections with the territory of present-day Poland in the Late Bronze Age and the Early Iron Age. The object is to discuss the provenance of the Lusatian bronze artefacts and analyse possible intercultural contacts with the north, across the Carpathians.
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Abstract

Second law analysis (entropy generation) for the steady two-dimensional laminar forced convection flow, heat and mass transfer of an incompressible viscous fluid past a nonlinearly stretching porous (permeable) wedge is numerically studied. The effects of viscous dissipation, temperature jump, and first-order chemical reaction on the flow over the wedge are also considered. The governing boundary layer equations for mass, momentum, energy and concentration are transformed using suitable similarity transformations to three nonlinear ordinary differential equations (ODEs). Then, the ODEs are solved by using a Keller’s box algorithm. The effects of various controlling parameters such as wedge angle parameter, velocity ratio parameter, suction/injection parameter, Prandtl number, Eckert number, temperature jump parameter, Schmidt number, and reaction rate parameter on dimensionless velocity, temperature, concentration, entropy generation number, and Bejan number are shown in graphs and analyzed. The results reveal that the entropy generation number increases with the increase of wedge angle parameter, while it decreases with the increase of velocity ratio parameter. Also, in order to validate the obtained numerical results of the present work, comparisons are made with the available results in the literature as special cases, and the results are found to be in a very good agreement.
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Abstract

The goal of this contribution is summary of physical – chemistry properties of usually used foundry silica and no – silica sands in Czech foundries. With the help of dilatometry analysis theoretical assumptions of influence of grain shape and size on dilatation value of sands were confirmed. Determined was the possibility of dilatometry analysis employment for preparing special (hybrid) sands with lower and/or more linear character of dilatation.
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Abstract

Along with the increase in popularity of the sewage sludge thermal treatment methods in Poland resulting from the implementation of European Union law, a management problem with ash, which is produced as a result of this process, appeared. The paper analyses the chemical composition and physical properties of fl y ash from thermal treatment of municipal sewage sludge in terms of its use in concrete technologies in relation to EN 450-1 Fly ash for concrete. Defi nition, specifi cations and conformity criteria (2012) and EN 197-1 Cement. Composition, specifi cations and conformity criteria for common cements (2011) standards. The tested material did not meet the requirements related to use of fl y ash for concrete production (chemical composition, low activity index, high water demand and fi neness), and as main and minor components for cement production. On the basis of the carried out research and analyses, it was found that the hardening slurry technology creates the greatest possibilities related to the management of fl y ash from thermal treatment of municipal sewage sludge.
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