Yes (87)
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87
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Hardness and elasticity of abrasive particles measured by instrumented indentation
Hvizdoš, P.; Zeleňák, Michal; Hloch, Sergej
2015 - English
Basic mechanical properties of seven types (from seven different sites) of abrasive garnet particles used for water jet cutting were measured using the technique of instrumented indentation (also called depth sensing indentation or nanoindentation). Hardness and modulus of elasticity were evaluated and compared. All the abrasives had similar measured mechanical properties (hardness 20 – 24.16 GPa), the highest values were found for the Czech garnet.
Keywords:
abrasive; garnet; hardness; elasticity; instrumented indentation
Available in digital repository of the ASCR
Hardness and elasticity of abrasive particles measured by instrumented indentation
Basic mechanical properties of seven types (from seven different sites) of abrasive garnet particles used for water jet cutting were measured using the technique of instrumented indentation (also ...
CFD model of multiphase flow in the abrasive water jet tool
Říha, Zdeněk
2015 - English
The possibility of using CFD fluid flow modeling in area of tools with abrasive water jet is described in the paper. The correct function of such tool is based on proper setting of multiphase flow of water, air and solid particles in the inner space of the tool. The multiphase fluid flow numerical simulation can provide information which show relation between the geometry and the flow field. Then, this stable CFD model of multiphase flow creates key to design of the tool able to work with higher efficiency.
Keywords:
abrasive water jet; multiphase flow; CFD model
Available in digital repository of the ASCR
CFD model of multiphase flow in the abrasive water jet tool
The possibility of using CFD fluid flow modeling in area of tools with abrasive water jet is described in the paper. The correct function of such tool is based on proper setting of multiphase flow ...
An a posteriori error estimate for the Stokes-Brinkman problem in a polygonal domain
Burda, P.; Hasal, Martin
2015 - English
We derive a residual based a posteriori error estimate for the Stokes-Brinkman problem on a two-dimensional polygonal domain. We use Taylor-Hood triangular elements. The link to the possible information on the regularity of the problem is discussed.
Keywords:
a posteriori error estimate; Stokes-Brinkman problem; Taylor-Hood triangular elements
Fulltext is available at external website.
An a posteriori error estimate for the Stokes-Brinkman problem in a polygonal domain
We derive a residual based a posteriori error estimate for the Stokes-Brinkman problem on a two-dimensional polygonal domain. We use Taylor-Hood triangular elements. The link to the possible ...
Erosion effects evaluation of pulsating water jet on brass EN 12164
Lehocká, D.; Klich, Jiří; Foldyna, Josef; Hloch, Sergej; Cárach, J.
2015 - English
The objective of this experiment is to verify an assumption that with decreasing value of feed rate, mass v material removal Δ of brass EN 12164 during cutting by pulsating water jet is increased, and to seek the mass erosion curve course depending on the change of feed rate v [mm·s-1]. The selected observed parameter was evaluated in two units of Δ [mg·s-1] and Δ [mg·mm-1]. Two mutually related experiments were carried out. In the pilot experiment, the curve originating at hydraulic power output of 15 kW was evaluated that was achieved in combination of nozzle diameter d [mm] and pressure p [MPa] - d/p [mm/MPa] = 1.0668/52; 1.3208/39; 1.6002/31. After the pilot experiment, another experiment followed in which a particular range of feed rate values v = 0.2 - 8 mm·s-1 was selected. This resulted in finding that different courses of erosion process exist for mass material removal expressed in the form of curve Δ [mg·s-1] and Δ [mg·mm-1], depending on feed rate v [mm·s-1].
Keywords:
pulsating water jet; erosion; mass material removal; brass
Available in digital repository of the ASCR
Erosion effects evaluation of pulsating water jet on brass EN 12164
The objective of this experiment is to verify an assumption that with decreasing value of feed rate, mass v material removal Δ of brass EN 12164 during cutting by pulsating water jet is increased, ...
Study and characterization of natural bentonite modified by Manganese Oxides
Dolinská, S.; Schütz, T.; Znamenáčková, I.; Vaculíková, Lenka
2015 - English
The paper describes the preparation of new composite based on on relatively cheap natural materials from domestic deposits and synthetically prepared manganese oxides. The manganese oxides were precipitated on the surface of activated sodium bentonite particles.
Keywords:
bentonite; manganese oxide; domestic deposits
Available in a digital repository NRGL
Study and characterization of natural bentonite modified by Manganese Oxides
The paper describes the preparation of new composite based on on relatively cheap natural materials from domestic deposits and synthetically prepared manganese oxides. The manganese oxides were ...
Modelling 2014
Blaheta, Radim; Starý, Jiří; Sysalová, Dagmar
2014 - English
MODELLING 2014 is a conference on Mathematical Modelling and Computational Methods in Applied Sciences and Engineering, which is held in Roznov pod Radhostem, Czech Republic, in June 2 - 6, 2014. The conference is organized by the IT4Innovations Centre of Excellence, Institute of Geonics AS CR, V’B-Technical University of Ostrava and International Association for Mathematics and Computers in Simulations (IMACS). MODELLING 2014 aims to be a forum for an exchange of ideas, insights and experience in di erent areas of mathematical modelling from numerical methods and computer aspects to applications of mathematical modelling methods. This international conference belongs to a series of conferences held in Roºnov 2009, Pilsen 2005, Pilsen 2001, Prague 1998 which started 20 years ago in Prague 1994. Main topics of the conference include computational modelling in engineering and science: multiscale modelling, multiphysics modelling, progress in discretization methods, effcient solvers, nonlinear problems, reliable computations, challenging applications of mathematical modelling methods, exploiting massively parallel computing facilities.
Keywords:
mathematical modelling; computational modelling; numerical methods
Available in a digital repository NRGL
Modelling 2014
MODELLING 2014 is a conference on Mathematical Modelling and Computational Methods in Applied Sciences and Engineering, which is held in Roznov pod Radhostem, Czech Republic, in June 2 - 6, 2014. ...
New Rock Mechanics Testing and Measuring System at the Institute of Geonics
Janeček, Ivan; Mishra, D.
2014 - English
New research tasks of the Department of laboratory research on geomaterials at the Institute of Geonics required improvement of experimental technique for investigation of the geomechanical properties of rocks and mastering of new rock testing methods as well. A new computer controlled hydraulic press with large set of adaptive accessories could meet the demands. With EU support of the project Institute of Clean Technologies for Mining and Utilization of Raw Materials for Energy Use (CZ.1.05/2.1.00/03.0082), a new Rock Mechanics System of the MTS Corporation was purchased, installed and put into operation.
Keywords:
rock testing; measurement under uniaxial and triaxial loading; testing of permeability and poroelastic response
Available in digital repository of the ASCR
New Rock Mechanics Testing and Measuring System at the Institute of Geonics
New research tasks of the Department of laboratory research on geomaterials at the Institute of Geonics required improvement of experimental technique for investigation of the geomechanical ...
The X-ray CT lab and the research at the Institute of Geonics AS CR
Souček, Kamil; Staš, Lubomír
2014 - English
In recent decades, non-destructive methods of materials analysis (Desrues 2006) have been used increasingly for the study of different kinds of materials. Especially, it concerns the method of the X-ray computed tomography (CT). This technique was invented in 1970's (Hounsfield 1972) and it quickly became an indispensable part of medicine. In the 1980's, this success in medicine encouraged the research and development of the X-ray CT applications in the field of materials engineering and consequently also in the field of geomaterials (Otani, Obara 2004). Nowadays, many applications are possible due to high resolution of individual building units in the tomographic cross-sections (so called voxels) with dimensions of units or tens of micrometres. To get this resolution, the use of the 2D and the 3D high-resolution X-ray CT, or the micro-CT with micro-focal sources of X-rays, and suitable linear or flat (2D) X-Ray detectors are preferred.
Keywords:
X-Ray computed tomography; non-destructive investigation of geomaterials; X-ray CT lab; rentgenové záření; materiály
Available in digital repository of the ASCR
The X-ray CT lab and the research at the Institute of Geonics AS CR
In recent decades, non-destructive methods of materials analysis (Desrues 2006) have been used increasingly for the study of different kinds of materials. Especially, it concerns the method of the ...
Stability of suspension bridges in lateral wind
Malík, Josef
2014 - English
The collapse of the original Tacoma suspension bridge has been studied in many papers. On 7 November 1940 around 10 a.m. the torsional oscillations appeared on the deck of the original Tacoma bridge after the loosening of one midspan cable band, which resulted in the lateral asymmetry of the construction. It seems that the loosening of the midspan cable band had a significant impact on the behavior of the bridge and in the end it resulted in the collapse.
Keywords:
stability; suspension bridges; torsional oscillations
Available in a digital repository NRGL
Stability of suspension bridges in lateral wind
The collapse of the original Tacoma suspension bridge has been studied in many papers. On 7 November 1940 around 10 a.m. the torsional oscillations appeared on the deck of the original Tacoma bridge ...
Geosite and geomorphosite assessment for geotourism purposes: a case study from the Vizovická vrchovina Highland, Eastern Moravia
Kirchner, Karel; Kubalíková, L.
2014 - English
Contribution deals with the problem of geodiversity, geoheritage and possibilities of their assessment for geotourism purposes. Geological, geomorphological and pedological sites are the most important resource for the geotourism activities. To find out which site can be used, it is necessary to identify, describe and assess various sites using a suitable assessment methodology. Based on the definition and concepts of geotourism and the assessment methods already used for geomorphosite assessment, authors propose five groups of assessment criteria. The method was used for assessing selected sites in the Vizovická vrchovina Highland.
Keywords:
geodiversity; numerical assessment; Outer Western Carpathians
Available in a digital repository NRGL
Geosite and geomorphosite assessment for geotourism purposes: a case study from the Vizovická vrchovina Highland, Eastern Moravia
Contribution deals with the problem of geodiversity, geoheritage and possibilities of their assessment for geotourism purposes. Geological, geomorphological and pedological sites are the most ...
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