Number of found documents: 290
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Influence of hydrodynamic nozzle wear on erosion effect of self-excited pulsating water jet
Klich, Jiří; Říha, Zdeněk; Foldyna, Vladimír
2017 - English
The article deals with the study of the wear of the hydrodynamic nozzle and its\ninfluence on the generation of a self-excited pulsating water jet (SPWJ). The nozzle\nwas monitored for the ability of the waterjet to erode the surface of the aluminum\nalloy EN AW 6060 at regular intervals. Keywords: hydrodynamic nozzle; waterjet; erosion Available in a digital repository NRGL
Influence of hydrodynamic nozzle wear on erosion effect of self-excited pulsating water jet

The article deals with the study of the wear of the hydrodynamic nozzle and its\ninfluence on the generation of a self-excited pulsating water jet (SPWJ). The nozzle\nwas monitored for the ability of ...

Klich, Jiří; Říha, Zdeněk; Foldyna, Vladimír
Ústav geoniky, 2017

Properties and characteristics of recycled garnet abrasives for AWJ
Martinec, Petr; Hlaváček, Petr; Ruppenthalová, Lucie; Sitek, Libor
2017 - English
The use of recycled garnet abrasive from sludge after cutting materials is a current\nproblem. The behavior of individual garnet abrasives in the AWJ process depends\non the geological origin of the garnets, which also affects all the material\ncharacteristics of the garnet recyclate. The parameters of the BARTON HPX80 and\nGMA 80 abrasive inputs and their recycled products were compared: mineralogical\ntype, apparent density, granularity, grain shape and mineralogical purity,\nmicrohardness data and the degree of damage to the garnet grains. All individual\nparameters of abrasives and their recyclates are reflected in the index of cutting\nefficiency of abrasive. The effect of abrasive material properties on cuttability of\nabrasives is synergistic. The new parameters in the evaluation of abrasives are\nmicro-hardness (brittleness criterion), specific surface and pore size distribution\n(internal grain damage criterion). Keywords: garnet; abrasive water jet; recycled abrasives; index of cutting efficiency of abrasive; microhardnes Available in a digital repository NRGL
Properties and characteristics of recycled garnet abrasives for AWJ

The use of recycled garnet abrasive from sludge after cutting materials is a current\nproblem. The behavior of individual garnet abrasives in the AWJ process depends\non the geological origin of the ...

Martinec, Petr; Hlaváček, Petr; Ruppenthalová, Lucie; Sitek, Libor
Ústav geoniky, 2017

Implicit constitutive solution scheme for Mohr-Coulomb plasticity
Sysala, Stanislav; Čermák, M.
2017 - English
This contribution summarizes an implicit constitutive solution\nscheme of the elastoplastic problem containing the Mohr-Coulomb yield cri-\nterion, a nonassociative \now rule, and a nonlinear isotropic hardening. The\npresented scheme builds upon the subdifferential formulation of the \now rule\nleading to several improvements. Mainly, it is possible to detect a position\nof the unknown stress tensor on the Mohr-Coulomb pyramid without blind\nguesswork. Further, a simplifed construction of the consistent tangent opera-\ntor is introduced. The presented results are important for an efficient solution\nof incremental boundary value elastoplastic problems. Keywords: Mohr-Coulomb plasticity; implicit constitutive solution scheme; consistent tangent operator Fulltext is available at external website.
Implicit constitutive solution scheme for Mohr-Coulomb plasticity

This contribution summarizes an implicit constitutive solution\nscheme of the elastoplastic problem containing the Mohr-Coulomb yield cri-\nterion, a nonassociative \now rule, and a nonlinear ...

Sysala, Stanislav; Čermák, M.
Ústav geoniky, 2017

Overlapping domain decomposition preconditioners for elliptic and parabolic problems in primal and mixed form
Blaheta, Radim
2017 - English
In this lecture, we concern the numerical solution of PDE problems and describe overlapping domain decomposition, which provides a tool for the construction of parallelizable Schwarz type iterative solvers and preconditioners. The idea of using overlapping domain decomposition goes back to Schwarz alternating method from 1870, see [1]. The analysis of this alternating iterative method was evolved by great mathematicians, see e.g. S.L. Sobolev (1936), R. Courant and D. Hilbert (1937), S.G. Michlin (1951), M. Práger (1958), I. Babuška (1958), F.E. Browder (1958). The use of overlapping domain decomposition for parallel computations started in the late eighties in the work of M. Dryja and O. Widlund [4], P.L. Lions [5, 6], S. Nepomnyaschikh [7] and others and continue up to the present days. The origin of the alternating Schwarz method is nicely described in [8]. Keywords: preconditioners; Schwarz method; matrix Ma Fulltext is available at external website.
Overlapping domain decomposition preconditioners for elliptic and parabolic problems in primal and mixed form

In this lecture, we concern the numerical solution of PDE problems and describe overlapping domain decomposition, which provides a tool for the construction of parallelizable Schwarz type iterative ...

Blaheta, Radim
Ústav geoniky, 2017

Dynamization of spatial data using location-based services: Tourist potential of industrial heritage
Malý, Jiří; Krejčí, Tomáš; Trojan, Jakub; Chudáček, Stanislav; Nováková, Eva
2017 - English
The paper deals with industrial heritage and its potential in tourism. Although the post-industrial landscape is an integral part of all the countries that went through a period of de-industrialization and economic transformation, presentation and publicity of valuable industrial monuments that are linked with post-industrial landscape in many cases are not fully utilized. This paper aims to acquaint readers with a possibility of transformation of data on industrial objects into augmented reality, while using location-based services. The final result is the web-based platform allowing easy data transformation. The paper has thus largely methodological-application character. The outcomes of the testing phase indicate that information about the objects do have their limits, but respecting them brings their effective performance in augmented reality. Keywords: location-based services; augmented reality; industrial heritage; tourism; Czech Republic Available in a digital repository NRGL
Dynamization of spatial data using location-based services: Tourist potential of industrial heritage

The paper deals with industrial heritage and its potential in tourism. Although the post-industrial landscape is an integral part of all the countries that went through a period of ...

Malý, Jiří; Krejčí, Tomáš; Trojan, Jakub; Chudáček, Stanislav; Nováková, Eva
Ústav geoniky, 2017

Effects of Water Jets on CNTs/concrete composite
Foldyna, Vladimír; Foldyna, Josef
2017 - English
Results of the resistance of carbon nanotubes concrete composite (CNTs/concrete\ncomposite) to the action of pulsating and continuous water jets are presented in\nthis paper. This work brings advanced results of fully hydrated CNTs/concrete\ncomposite (after 28 days) and it follows up the research of this composite\nhydrated 7 days. The experiments were focused at the determination of erosion\neffects of both types of water jets impinging the surface of reference (concrete) and\nCNTs/concrete composite samples. Erosion effects of water jets were evaluated in\nterms of material removal rate. Tests were performed at various operating\nparameters of continuous and pulsating water jets. Keywords: CNTs/concrete composite; continuous and pulsating water jet; material removal Available in a digital repository NRGL
Effects of Water Jets on CNTs/concrete composite

Results of the resistance of carbon nanotubes concrete composite (CNTs/concrete\ncomposite) to the action of pulsating and continuous water jets are presented in\nthis paper. This work brings advanced ...

Foldyna, Vladimír; Foldyna, Josef
Ústav geoniky, 2017

Prospective of using pulsating water jet peening as a surface treatment process
Srivastava, M.; Hloch, Sergej; Tripathi, R.; Chattopadhyaya, S.; Dixit, A. R.; Foldyna, Josef; Hvizdoš, P.; Fides, M.; Adamčík, P.
2017 - English
This study focusses on exploring the effect of using Pulsating water jet technology\nas a surface treatment process. The AISI 304 plate samples were subjected to\nthe treatment process using circular nozzle at different levels of pressure and\nstand-off distance combination with variation of traverse speed. For evaluating\nthe effect of peening the surface residual stress was measured using the x-ray\ndiffraction technique. The results showed that the initial tensile residual stresses\non the surface were relieved and converted to compressive residual stress.\nThe present study shows that the new technology can be used as a potential\nsurface treatment method. Keywords: residual stress; water jet; peening Available in a digital repository NRGL
Prospective of using pulsating water jet peening as a surface treatment process

This study focusses on exploring the effect of using Pulsating water jet technology\nas a surface treatment process. The AISI 304 plate samples were subjected to\nthe treatment process using circular ...

Srivastava, M.; Hloch, Sergej; Tripathi, R.; Chattopadhyaya, S.; Dixit, A. R.; Foldyna, Josef; Hvizdoš, P.; Fides, M.; Adamčík, P.
Ústav geoniky, 2017

Local geoheritage: its importance and potential for geotourist and recreational activities (a case study from Lomnicko area)
Kirchner, Karel; Kubalíková, L.; Bajer, A.
2017 - English
Geodiversity, respectively its valuable part – geoheritage is considered an important resource for the geotourism and recreation purposes. In the C.R., there are a lot of examples of such use of geoheritage: sandstone rock cities, karst areas or polygenetic relief at mountain areas and others. These geoheritage features are usually significant on the national level, their existence assure the attractiveness of the given area, enables the geotourist and recreational activities and support the local and regional development. However, in the local scale, the geodiversity (respectively geoheritage, represented by particular geosites and geomorphosites) can also serve the above mentioned purposes. The paper presents the example from Lomnicko area which can be seen as an “average” area from the geodiversity/geoheritage point of view on the national level, but on the local and regional level, there is a considerable number of geosites and geomorphosites with a potential for geotourism and recreation. Keywords: geodiversity; geosite; geomorphosite; geotourism Available in a digital repository NRGL
Local geoheritage: its importance and potential for geotourist and recreational activities (a case study from Lomnicko area)

Geodiversity, respectively its valuable part – geoheritage is considered an important resource for the geotourism and recreation purposes. In the C.R., there are a lot of examples of such use of ...

Kirchner, Karel; Kubalíková, L.; Bajer, A.
Ústav geoniky, 2017

Abrasive water jet drilling of cooling holes in aeroengines: preliminary experimental study
Hlaváček, Petr; Zlámal, T.; Sitek, Libor; Georgiovská, Lucie
2017 - English
This paper addresses an experimental investigation on the feasibility of using\nabrasive water jet (AWJ) for the drilling of small-diameter holes in aeroengines\ncomponents. These components are sprayed with ceramic thermal barrier coating\n(TBC). The required holes are typically 0.5 to 1 mm in diameter with a drilling\nangle of 30 to 90 deg. The parameters of the AWJ were varied to study their effects\non both quantitative and qualitative hole drilling parameters. Keywords: abrasive water jet; drilling; thermal barrier coating Available in a digital repository NRGL
Abrasive water jet drilling of cooling holes in aeroengines: preliminary experimental study

This paper addresses an experimental investigation on the feasibility of using\nabrasive water jet (AWJ) for the drilling of small-diameter holes in aeroengines\ncomponents. These components are ...

Hlaváček, Petr; Zlámal, T.; Sitek, Libor; Georgiovská, Lucie
Ústav geoniky, 2017

Evaluation of quality of cut surfaces created by abrasive water jet according to swiss standard SN 214001
Klichová, Dagmar; Gurková, Lucie
2017 - English
The article focuses on the evaluation of the quality of cut surfaces created by\nan abrasive water jet (AWJ) according to the Swiss standard SN 214001 (2010).\nThe standard presents a quantified description of the texture of the cut. It defines\nnew parameters and methods of parameter measurements used in order to\ncategorize the cut surface in various quality levels Q. They are so far the most\ncommonly applied form of the qualitative description of the quality of the cut\nsurfaces created by the AWJ technology. Keywords: surface quality; abrasive water jet; standard parameters Available on request at various institutes of the ASCR
Evaluation of quality of cut surfaces created by abrasive water jet according to swiss standard SN 214001

The article focuses on the evaluation of the quality of cut surfaces created by\nan abrasive water jet (AWJ) according to the Swiss standard SN 214001 (2010).\nThe standard presents a quantified ...

Klichová, Dagmar; Gurková, Lucie
Ústav geoniky, 2017

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