Number of found documents: 150
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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

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

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

Erosion capability of ultra-high-speed continuous waterjet and pulsating waterjet: the comparison
Sitek, Libor; Hlaváček, Petr; Klichová, Dagmar; Trieb, F.; Pude, F.
2017 - English
Advantages and possibilities of continuous ultra-high-speed waterjets (with\npressures of 600 MPa and more) when cutting metals are well known to\nthe professional public both from scientific studies and from practice. In addition\nto efficiency increased as water pressure increases and reduced water\nconsumption, abrasive consumption can also be reduced in the case of abrasive\nwaterjet. Ultra-high-speed waterjet technology allows not only to cut metal sheets\nwith pure water, but also allows cutting of harder materials such as ceramics.\nDespite the initial suspicion and technical problems associated with the reliability\nand sealing of some hyperpressure elements, high-pressure devices generating\nwater pressures around 600 MPa are now commercially available. However, no\ncomparison has been made so far concerning the efficiency of these jets with\nacoustically modulated high-speed pulsating waterjets using relatively low\npressures and higher water flow rates when eroding metallic materials.\nThe article compares cuts made by pure ultra-high-speed waterjet generated at\nhyperpressures (from 500 to 800 MPa) with erosive capabilities of pulsating\nwaterjets generated on the contrary at water pressures in the order of tens of MPa\non three metallic materials (stainless steel, mild steel and copper) using the same\njet hydraulic power. Keywords: hyperpressure; hydraulic power; ultra-high-speed waterjet; pulsating waterjet Available in a digital repository NRGL
Erosion capability of ultra-high-speed continuous waterjet and pulsating waterjet: the comparison

Advantages and possibilities of continuous ultra-high-speed waterjets (with\npressures of 600 MPa and more) when cutting metals are well known to\nthe professional public both from scientific studies ...

Sitek, Libor; Hlaváček, Petr; Klichová, Dagmar; Trieb, F.; Pude, F.
Ústav geoniky, 2017

Velocity measurements on continuous micro water jet using fluorescent PMMA seeding particles
Zeleňák, Michal; Ščučka, Jiří; Souček, Kamil
2017 - English
The paper deals with application of optical diagnostic techniques for velocity\nmeasurements of continuous micro water jet. The combination of Particle image\nvelocimetry, Particle tracking velocimetry, Laser induced fluorescence and\nShadowgraphy methods have been applied together with the use of fluorescent\nPMMA seeding particles. An experimental closed water circuit was designed with\na low-pressure water pump, and a series of experiments was conducted to\nmeasure the velocity of seeding particles in the water jet flow below the diamond\nmicro-nozzle outlet. The basic principles of the methods used in experiments are\nalso described. Keywords: micro water jet; fluorescent PMMA particles; velocity; LIF; PTV; PIV Available in a digital repository NRGL
Velocity measurements on continuous micro water jet using fluorescent PMMA seeding particles

The paper deals with application of optical diagnostic techniques for velocity\nmeasurements of continuous micro water jet. The combination of Particle image\nvelocimetry, Particle tracking ...

Zeleňák, Michal; Ščučka, Jiří; Souček, Kamil
Ústav geoniky, 2017

Dílčí zpráva V/2017 - Hodnocení monitoringu napěťodeformačního stavu horninového masivu při dobývání sloje 30 (634) v rámci zkušebního provozu dobývací metody chodba-pilíř v OPJ Dolu ČSM-SEVER
Waclawik, Petr; Kukutsch, Radovan; Kajzar, Vlastimil; Staš, Lubomír
2017 - Czech
Monitoring napěťodeformačního stavu horninového masivu je nezbytným předpokladem pro ověření nové neschválené dobývací metody chodba-pilíř a jejího dalšího použití v podmínkách české části hornoslezské uhelné pánve. Tato dobývací metoda je projektována pouze na základě zkušeností a postupů, které jsou ověřeny v odlišných přírodních podmínkách a hloubkách pod povrchem a proto je nezbytná její verifikace pro podmínky české části hornoslezské pánve na základě geotechnického monitoringu. Předkládaná zpráva je zpracována na základě smlouvy o dílo č. 942/50/10, kde se Ústav Geoniky AV ČR, v.v zavazuje provádět pravidelné vyhodnocování dat monitoringu napěťodeformačního stavu horninového masivu. V souladu s výše uvedenou smlouvou, je zpráva zpracována v 6-ti měsíčním intervalu a navazuje tak na dílčí zprávu IV/2016 (Waclawik et al. 2016) předanou odběrateli v dubnu tohoto roku. Průběžné výsledky geotechnického monitoringu, tak jak zkušenosti získané v době dobývání první dobývky V, ukazují na specifika přírodních podmínek v lokalitě zkušebního provozu nové neschválené dobývací metody chodba-pilíř. Monitoring of the deformation stress state of the rock mass is a prerequisite for the verification of unapproved new mining methods hall-pillar and its further application in the Czech part of the Upper Silesian coal basin. This mining method is designed on the basis of experiences and practices that are verified in different natural conditions and depths below the surface and is therefore essential for the verification of conditions for the Czech part of the Upper Silesian Basin based on geotechnical monitoring. The present report is prepared on the basis of a contract no. 942/50/10, where the Institute of Geonics, v.v agrees to make periodic evaluation of monitoring data napěťodeformačního state of the rock mass. In accordance with the aforementioned agreement, the message is processed in the six-month period and continues in the interim report IV/2016 (Waclawik et al. 2016) passed buyers in April this year. Interim results of the geotechnical monitoring, such as the experience gained during the first conquest dobývky V show specifics of natural conditions in trial operation unapproved new mining methods hall-pillar.\n Keywords: monitoring; room and pillar; rock mass Available in a digital repository NRGL
Dílčí zpráva V/2017 - Hodnocení monitoringu napěťodeformačního stavu horninového masivu při dobývání sloje 30 (634) v rámci zkušebního provozu dobývací metody chodba-pilíř v OPJ Dolu ČSM-SEVER

Monitoring napěťodeformačního stavu horninového masivu je nezbytným předpokladem pro ověření nové neschválené dobývací metody chodba-pilíř a jejího dalšího použití v podmínkách české části ...

Waclawik, Petr; Kukutsch, Radovan; Kajzar, Vlastimil; Staš, Lubomír
Ústav geoniky, 2017

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