Ano (87)
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Removal of polyurea spray coatings from the surface of cement concrete by water jet technology
Ščučka, Jiří; Bódi, Z.; Hlaváček, Petr; Klich, Jiří; Martinec, Petr; Foldyna, Josef
2013 - anglický
The paper is focused on the removal of polyurea spray coatings from the surface of cement concrete by the water jet technology. A series of experiments was conducted to disintegrate a defined polyurea spray coat layer on the surface of cement concrete tiles using different configurations of the water jet system. The results of these experiments have confirmed that the continuous water jet was highly effective in removing the spray coat, causing no damage to the concrete substrate underneath. The partial experimental results have also indicated that this process can be used to produce an anti-skid finish on polyurea spray coatings applied onto horizontal structures.
Klíčová slova:
concrete; polyurea spray coating; removal; water jet
Plné texty jsou dostupné v digitálním repozitáři NUŠL
Removal of polyurea spray coatings from the surface of cement concrete by water jet technology
The paper is focused on the removal of polyurea spray coatings from the surface of cement concrete by the water jet technology. A series of experiments was conducted to disintegrate a defined polyurea ...
Relief assessment methodology with respect to geoheritage based on example of the Deblínská vrchovina Highland
Kirchner, Karel; Kubalíková, L.
2013 - anglický
The article deals with history, presence and possible future development of geoconservation in the Czech Republic. Both examples of legislative instruments and other geoconservation activities are presented. Practically, the geoconservation activities are shown at the case study of the central part of the Deblínská vrchovina Highland (Maršov valley area) in the south-eastern part of the Czech Republic.
Klíčová slova:
geoheritage; geomorphosites assessment; Maršov valley
Dokument je dostupný na externích webových stránkách.
Relief assessment methodology with respect to geoheritage based on example of the Deblínská vrchovina Highland
The article deals with history, presence and possible future development of geoconservation in the Czech Republic. Both examples of legislative instruments and other geoconservation activities are ...
Measurement and evaluation of pulsating water jet peening intensity
Hlaváček, Petr; Klich, Jiří; Foldyna, Josef; Sitek, Libor
2013 - anglický
Pulsating water jet peening is a promising method in surface treatment. It has the potential to induce compressive residual stresses that benefit the fatigue life of components similar to the other peening process. In this paper experimental results obtained by action of pulsating water jet on Almen strips are presented.
Klíčová slova:
pulsating water jet; peening intensity; Almen strips
Plné texty jsou dostupné v digitálním repozitáři NUŠL
Measurement and evaluation of pulsating water jet peening intensity
Pulsating water jet peening is a promising method in surface treatment. It has the potential to induce compressive residual stresses that benefit the fatigue life of components similar to the other ...
Research on waterjet in Institute of Geonics of the AS CR from 1990 to 2006
Vašek, Jaroslav
2013 - anglický
The paper is continuation of an article published in the proceedings of the conference "Water Jet 2011 - Research, Development, Applications”. By 1990, the work is briefly described in the article (VAŠEK 2011). The follow-up work carried out in the period 1990 - 2006 is the subject of this article. The paper gives a brief overview of the author's participation at the World Mining Congress in Beijing (1990), a collaboration with CNR Canada, CNR Cagliari (Italy), the organization of international conferences GEOMECHNICS 91, 93 and 96. The cooperation with University of Missouri Rola (hereinafter UMR) USA, Cornerstone Technologies and Pennsylvania Micronics, cooperation within the project EU-Inco Copernicus (1995 - 1999) and the project of Grant Agency of the Academy of Sciences of the Czech Republic (hereinafter GAAV) "Mechanical breakages and disintegration processes of coal and rock - theoretical aspects, applications, outlook” (2001-2006) are also presented.
Klíčová slova:
water jet; history; period 1990 - 2006
Plné texty jsou dostupné v digitálním repozitáři NUŠL
Research on waterjet in Institute of Geonics of the AS CR from 1990 to 2006
The paper is continuation of an article published in the proceedings of the conference "Water Jet 2011 - Research, Development, Applications”. By 1990, the work is briefly described in the article ...
Thermal behaviour of organically modified clays
Plevová, Eva; Vaculíková, Lenka; Vítámvásová, E.; Šugárková, Věra; Martynková, G.S.
2013 - anglický
The clay minerals were modified by two alkylammonium cations under sorption procedure. T X-ray powder diffraction and FT-IR spectroscopy were used to evaluate the intercalation process of organic cations int the clay structure. The organo - montmorillonites exhibited IR spectra giving evidence about sorption or intercalation of the alkylammonium cations. The enhancement of the basal spacing obtained by X-ray diffraction confirmed the intercalation process of cations into montmorillonite and vermiculite samples. Thermal behaviour of the modified clay minerals was investigated by simultaneous thermogravimetry and differential thermal analysis. The organically modified montmorillonites exhibited the higher values of temperatures related to the total melting. Also the temperatures of exotherm effects connected to recrystallization and transformation increased with the concentration of alkylammonium salts. The temperatures of dehydratation and dehydroxilation decreased with concentration of alkylammonium cations. Vermilulite samples showed generally reducing of their thermal stability.
Klíčová slova:
clay minerals; alkylammonium cations; intercalation; thermal analysis
Plné texty jsou dostupné v digitálním repozitáři NUŠL
Thermal behaviour of organically modified clays
The clay minerals were modified by two alkylammonium cations under sorption procedure. T X-ray powder diffraction and FT-IR spectroscopy were used to evaluate the intercalation process of organic ...
(Semi) regular tetrahedral tilings
Kolcun, Alexej
2013 - anglický
Triangulation 2D and 3D methods represent an import ant part of numerical modeling process (e.g. FEM). In many applications it is suitable to use triangulati ons with a regular structure. Moreover, decompositi on with a limited number of different types of tetrahedra ena bles to reduce the storage and computational demand s in the whole modeling process. The submitted contribution presents an overview of possible 3D decompositions using one tetrahedron (regular tilings). These decomposit ions are confronted with decompositions using six d ifferent types of tetrahedra (orthogonal structured tilings) . Considering the shape expressivity of particular methods, the paper presents a structure of possible decompositio ns and comparison of storage demands of the used decompositions.
Klíčová slova:
tetrahedron; regular tessellation; voxel grid; conform decomposition
Dokument je dostupný na externích webových stránkách.
(Semi) regular tetrahedral tilings
Triangulation 2D and 3D methods represent an import ant part of numerical modeling process (e.g. FEM). In many applications it is suitable to use triangulati ons with a regular structure. ...
Ornamental stones surface finishing by pulsating jet: a project for an industrial application
Bortolussi, A.; Matzuzzi, C.; Foldyna, Josef; Sitek, Libor
2013 - anglický
The paper deals with a project developed to lead the application of pulsating jet technology for ornamental stone surface finishing from a research phase to an industrial level. The project is based on the financial support of the Regional Government of Sardinia – Italy and on the contributes of some Sardinian companies interested in the industrial developments.
Klíčová slova:
pulsating jet; ornamental stones; surface finishing
Plné texty jsou dostupné v digitálním repozitáři NUŠL
Ornamental stones surface finishing by pulsating jet: a project for an industrial application
The paper deals with a project developed to lead the application of pulsating jet technology for ornamental stone surface finishing from a research phase to an industrial level. The project is based ...
The measurement of the velocity of abrasive particles at the suction part of the cutting head
Foldyna, Josef; Zeleňák, Michal; Klich, Jiří; Hlaváček, Petr; Sitek, Libor
2013 - anglický
To be able to optimize the design of the abrasive cutting head using numerical simulation, it is necessary to gather as much information about processes occurring in the cutting head as possible. The development of the numerical model of processes occurring in the abrasive water jet cutting head during the process of creation and forming of abrasive water jet is currently in progress at the Institute of Geonics in Ostrava. The verification of the model requires, among others, to determine the behaviour of abrasive particles at the input of the cutting head. Therefore, the visualisation of abrasive particles at the input using various parameters of abrasive jet and its subsequent analysis was performed using shadowgraphy (backlighting) technique and the results are presented in the paper.
Klíčová slova:
abrasive water jet; velocity of abrasive particles; shadowgraphy
Plné texty jsou dostupné v digitálním repozitáři NUŠL
The measurement of the velocity of abrasive particles at the suction part of the cutting head
To be able to optimize the design of the abrasive cutting head using numerical simulation, it is necessary to gather as much information about processes occurring in the cutting head as possible. The ...
Effects of pulsating water jet on materials with variously modified surface
Klich, Jiří; Klichová, Dagmar; Hlaváček, Petr
2013 - anglický
The paper deals with determination of erosion effects of pulsating water jet impinging the surface of aluminium alloy samples treated by various techniques (rough and fine milling, planing and rolling). The influence of the initial surface topography on the final topography of the sample exposed to pulsating water jet was investigated. Erosion of surface layer was analysed and discussed with respect to the traversing velocity of the jet. It was found, that properties of the initial surface have a significant impact on the final topography. Degree of erosion of the surface was determined by the measurement of surface parameter Ra.
Klíčová slova:
pulsating water jet; surface topography; material erosion
Plné texty jsou dostupné v digitálním repozitáři NUŠL
Effects of pulsating water jet on materials with variously modified surface
The paper deals with determination of erosion effects of pulsating water jet impinging the surface of aluminium alloy samples treated by various techniques (rough and fine milling, planing and ...
Study of behavior of concrete and cement based composite materials exposed to high temperatures
Bodnárová, L.; Horák, D.; Válek, J.; Hela, R.; Sitek, Libor
2013 - anglický
The paper describes possibilities of observation of behaviour of concrete and cement based composite material exposed to high temperatures. Nowadays, for large-scale tests of behaviour of concrete exposed to high temperatures, testing devices of certified fire testing stations in the Czech Republic and surrounding states are used. These tests are quite expensive. For experimental verification of smaller test specimens, a testing device was built at the Technical University in Brno, where tests of thermal loading of concrete tests specimens of various sizes can be carried out (dimensions up to 800 x 800 x 800 mm or slabs up to 1100 mm of length). The testing device opens new ways of observation of behaviour of concrete and cement based composite materials exposed to high temperatures as well as preparation of specimens for observation of interaction of water jet and concrete degraded by action of high temperatures.
Klíčová slova:
concrete; high temperature; water jet
Plné texty jsou dostupné v digitálním repozitáři NUŠL
Study of behavior of concrete and cement based composite materials exposed to high temperatures
The paper describes possibilities of observation of behaviour of concrete and cement based composite material exposed to high temperatures. Nowadays, for large-scale tests of behaviour of concrete ...
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