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CFD code as a helper for the design of the water jet cutting device
Říha, Zdeněk
The efficiency of the amplification of high pressure pulsations in the geometric transition between larger and smaller pipes is analysed in this paper. Three types of geometric transitions are compared in the paper: step change, conical and radius change of pipe diameters. In other words, water flow in a device for water jet cleaning and cutting is evaluated. There are ultrasonic pulsations of high pressure in the given domain.
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Scientific monitoring of geomechanical stability and seismic load of national cultural monument Jeroným Mine, Karlovy Vary Region
Žůrek, P. ; Kořínek, R. ; Michalčík, P. ; Daněk, T. ; Kaláb, Zdeněk ; Knejzlík, Jaromír ; Kukutsch, Radovan ; Lednická, Markéta
The research report presents the results of the seismic load of mining work through station JER1, description of the experimental measurements and seismological report briefly on the results of continuous measurement of selected parameters using distributed measurement systems, presents the results of monitoring of geological and geomechanical monitoring.
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Floods – a natural phenomenon that would always shake to surprise
Munzar, Jan ; Ondráček, Stanislav
In the last twenty years, disastrous floods occurring in the Czech Republic affected smaller or larger areas (three extreme events occurred in 2010 alone). A particularly great surprise was the flood disaster in the summer of 1997, which caught a greater part of the population unprepared because several generations had not experienced a similar hydrological extreme – the historic memory of floods had been lost. In the past, people living along large rivers took into account the usual and often annually occurring natural phenomenon. However, the relation of today’s inhabitants in riverine landscapes and of the whole society to rivers and phenomena occurring on them changed during the 20th century. This is why the awareness of floods should be constantly restored, which is the aim of this work. The paper reminds and documents several disastrous floods, today already forgotten, occurring on Moravian or Bohemian rivers from the 16th century until the present and their impacts.
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Surface subsidence induced by exploitation of the first seams of multi-seams Carboniferous deposits
Hortvík, Karel ; Černý, I.
Exploatace multislojového uhelného ložiska postupuje z technologických i ekonomických důvodů vždy od výše uložených slojí směrem do větších hloubek. Při hlubinném dobývání uhelných slojí stěnovými poruby na řízený zával se jako následek hornické činnosti vytváří na povrchu poklesová kotlina.Její velikost – tedy rozsah a hloubka – je závislá na více faktorech. Rozsah poklesové kotliny odpovídá hloubce uložení ložiska a mezným úhlům vlivu nadložních hornin, které vyplývají z geologických a geomechanických vlastností nadloží. Hloubka poklesové kotliny odpovídá velikosti vyrubané plochy v dané sloji nebo slojích, vydobyté mocnosti ložiska, času uplynulému od ukončení dobývání, způsobu likvidace vydobytých prostor a velmi důležitá je i existence případných dřívějších dobývacích prací (v nadloží).
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