|
|
Korteweg fluids - modeling, analysis and computer simulations
Blaškovičová, Monika ; Málek, Josef (advisor) ; Řehoř, Martin (referee)
We present two possible thermodynamical approaches towards a derivation of a model, proposed by Korteweg at the beginning of the 20th century, that is suitable to describe phase transitions liquid-vapor with non-sharp interfaces. The first approach (Dunn, Serrin (1985)) is based on classical rational continuum thermodynamics. The second approach (Heida, Málek (2010)) stems from the principles of classical nonequilibrium continuum thermodynamics. We compare both approaches in favor of the second one. The considered constitutive equation for the Cauchy stress is nonlinear. Nonlinearity and higher order derivatives of the density makes the analysis of relevant problems for the Navier-Stokes- Korteweg (NSK) fluid more difficult in comparison to problems concerning Navier-Stokes equations. Special attention is devoted to the appropriate choice of the boundary conditions. We also investigate the influence of compressibility on the stability of bubbles by comparing numerical simulations for compressible NSK fluid and its incompressible variant. Instabilities observed for a compressible NSK fluid are due to the pressure that has a different meaning for incompressible fluid. Powered by TCPDF (www.tcpdf.org)
|
|
|
The validity of climbing specific tests to the climbling performance
Řehoř, Marek ; Baláš, Jiří (advisor) ; Strejcová, Barbora (referee)
Name The validity of specific tests of flexibility toward climbing performance Goal To attest the validity of specific tests of flexibility in climbing Method 202 subjects were measured, of this number 136 were men 176,8 cm ± 8,9 cm tall and weighing in at 68,9 kg ± 12,0 kg and 66 were women 168,2 cm ± 15,2 cm tall and weighing in at 62,8 kg ± 13,1 kg. Specific flexibility was measured through three tests: bent knee foot raise test, straight knee foot raise test and foot loading test. The degree of validity of tests has been expressed by the correlation between the climbing performance and the results of the specific flexibility tests. Results All the tests were showing medium dependence to the climbing performance with the correlating coefficient values being: bent knee foot raise test r=0,49, foot loading test r=0,49 straight knee foot raise test r=0,44. These correlating coefficients were calculated from the relative values of test results by averaging the left and right foot results and dividing the resulting number by the height of the subject. Summary Tests used are a suitable indicator of climbing specific flexibility. Keywords Validity, flexibility, sport climbing
|
|
|
Behaviour of new types of material models in a squeeze flow geometry
Řehoř, Martin ; Průša, Vít (advisor) ; Hron, Jaroslav (referee)
Investigation of material behaviour in a squeeze flow geometry provides an impor- tant technique in rheology and it is relevant also from the technological point of view (some types of dampers, compression moulding). To our best knowledge, the sque- eze flow has not been solved for fluids-like materials with pressure-dependent material moduli. In the main scope of the present thesis, an incompressible fluid whose visco- sity strongly depends on the pressure is studied in both the perfect-slip and the no-slip squeeze flow. It is shown that such a material model can provide interesting departures compared to the classical model for viscous (Navier-Stokes) fluid even on the level of analytical solutions, which are obtained using some physically relevant simplificati- ons. Numerical simulation of a free boundary problem for the no-slip squeeze flow is then developed in the thesis using body-fitted curvilinear coordinates and spectral collocation method. An interesting behaviour is expected especially in the corners of the computational domain where the stress singularities are normally located. Unfor- tunately, numerical results reveal some fundamental drawbacks related to the physical model and its possible improvement is discussed at the end of the thesis.
|
|
| |
|
|
Influence of pedological characteristics of site and of reclamation methodology on biological cover development on Radovesice dump
Říhová, Jitka ; Řehoř, Michal (advisor) ; Tonika, Jaroslav (referee)
The North Bohemian Basin represents important and high valued brown coal resources. Remove coal from the ground in surface mines is an impairment of nature and landscape. Reclamation work aims to identify changes, analyse them and restore the impacted area. The analysed dump (Radovesice dump) was used as an outsider dump of the Bílina mine. Reclamation works are in process on this area - especially forest and agricultural reclamation. In the first part of this bachelor thesis pedological and vegetation research are done. Therfore, two areas of the Radovesice site were analysed. Forest reclamation area , which is labeled Radovesice I and succession area labeled Radovesice XVII A. The second part deals with the influence on the vegetation overlay caused by the area's location and soil substrate. In the conclusion of the thesis suggestions are given how to support succession on relamation areas, based on the awareness of the analysed site and current scientific knowledge. Keywords reclamation, soil, vegetation, Radovesice vi
|
|
| |
|
| |
|
|
Labour market policies in the Czech republic
Řehoř, Marek ; Pavelka, Tomáš (advisor) ; Adámek, Petr (referee)
This bachelor thesis focuses on the labour market policies in the Czech republic. In the theoretical part the labour market is defined and the issue of unemployment is decribed. Further, labour market policies in the Czech republic are described, especially its tools. In the practical part data on unemployment and usage of labour market policies tools are analysed. Finally, efficiency of the labour market policies in the Czech republic is evaluated. Labour market policies in the Czech republic are efficient, because costs on unemployed persons are in comparisom with expenditure on labour market policies high. Labour market policies in the Czech republic also focuse on vulnerability groups on the labour market as young persons or persons with low skills.
|
|
|
Qualitative and quantitative analysis of clay soils
Šašek, Petr ; Viani, Alberto ; Ševčík, Radek ; Fabeš, Roman ; Řehoř, M.
Clay minerals are a group of aluminum silicates with a layered structure, which is formed by tetrahedrally and octahedrally arranged molecules with cations of potassium, magnesium, sodium and others. By combining layers of octahedra and tetrahedra several types of layered structures may be produced, which can form various types of clay minerals in nature. Clay minerals are divided into three main groups: kaolinite, smectite and illite. The aim of the study was to qualitatively and quantitatively analyse the clay minerals in soil samples; the main objective was to determine the phase transition on the boundary of smectite and illite phases. For this purpose XRD analysis with Rietveld refinement was employed.
|
guest ::
RSS feed.