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Hodnocení mechanických vlastností částicových polymerních kompozitů pomocí měření mikrotvrdosti
Minster, Jiří ; Berka, L. ; Hristova, J.
The applicability of Vickers microhardness measurements for mechanical assessment of heterogeneous polymer composites (filled polymer composites and polymer concretes) is discussed. Two types of composites based on epoxy and polyester matrices were investigated and two types of finely dispersed fillers were used with the 20% volumetric concentration of the individual fillers. The reinforcing effect of the hard filler and changes in the microhardness (i.e. in the yield strengths and moduli) in the neighbourhood of filler micrograins have been substantiated.
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Site investigation of wooden structures
Kloiber, Michal ; Holan, J.
The investigation deals with assessment of gothic part of roof frame situated in the Church Nanebevzetí Panny Marie a sv. Ondřeje at Starém Hobzí. A part of investigation there was a proposal of stabilization treatment prepared with respect of historical value of the church. The identification of main abiotic and biotic factors of degradation was performed with the aim of transition determination between the sound and destroyed parts. There was proposed mainly the construction arrangements out of preservative treatment because of their substantial effectiveness. The presumption of such arrangements there are preservative treatments such as sterilization and/or chemical preservation.
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The Life and the Work of the Prague Carpenter Michael Ranek
Bláha, Jiří
The designs of the low-cost roof trusses created at the end of 1820s by Prague carpenter of Hungarian origin Michael Ranek (1770-1842) form a sort of link between traditional trusses with collars and modern purlin constructions. The swift adoption of Ranek’s truss among carpenters was helped by the relationship of trusses to traditional collar systems, easier handling of beams with smaller profiles and last but, not least, its simplicity during fabrication and erection. During the course of the second half of the 19th century Ranek’s trusses, together with traditional trusses with collar beams, were forced out by new, progressive constructions, especially by the generally widespread purlin trusses.
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Bezmaticová formulace stochastické Newmarkovy metody
Fischer, Cyril
A response of an arbitrary discretized system to the random movement has been solved in probabilistic terms. The excitation has been defined as a combination of the time modulated band limited stationary random processes approximating the evolutionary power spectra of a true seismic record. The solution is based either on the modified version of the stochastic Newmark method or on the spectral differential decomposition of the excitation. Special attention has been paid to the applicability of the methods to the sparse problems, especially to their matrix-free formulation.
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