National Repository of Grey Literature 5 records found  Search took 0.00 seconds. 
Inhomogeneous cosmological models
Vrba, David ; Svítek, Otakar (advisor) ; Pravda, Vojtěch (referee) ; Žofka, Martin (referee)
In this work we study inhomogeneous cosmological models. After a brief review of applications of inhomogeneous solutions to Einstein equations in cosmology, we give a short description of the most widely used inhomogeneous cosmological models. In the second chapter we study in detail geometrical prop- erties of the Szekeres spacetime and we are concerned with the interpretation of the metric functions in different types of geometries. In the last chapter we model inhomogeneity in Szekeres spacetime. We derive formula for the density contrast and investigate its behaviour. We also derive conditions for the density extremes that are necessary for avoiding the shell crossing singularity in Szekeres spacetime. 1
Effect of Ferrite Nanoparticles on the Thermal Exposure of Biological Tissue Phantom by Microwave Thermotherapy
Fišer, Ivan ; Vorlíček, Jaroslav (advisor) ; Vrba, David (referee)
Goal of this master thesis is describe effect of ferrite nanopartickles FeSi and FeH on the thermal exposure of biological tissue phantom by microwave Thermotherapy. Blank samples and the samples with increased concentration nanopartickles FeSi and FeH were prepared. Exposition was performed by open cavity resonator with 2, 45 GHz generator. Temperature profiles were taken by thermocamera Flir P25. Results of both types of samples were compared and were statistically interpreted. Agar samples with nanopartickles FeSi and FeH show higher increase of temperature, than blank samples. The differences are not statistically significant. Keywords: Microwave thermotherapy, nanopartickles
Determination of Optical Properties of Surfaces for Use in Cultural Heritage Protection
Kocour, Vladimír ; Bryscejn, Jan ; Vrba, David ; Valach, Jaroslav
In this paper we would like to present a simple method of surface reflectance measurement, then to discuss relation between reflectance and surface appearance and what it indicates in the context of shape reconstruction and surface protection.

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