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On higher-order space-time discretization of an nonlinear aeroelastic problem with the consideration of large displacements
Sváček, P. ; Horáček, Jaromír
This paper focuses on the mathematical and numerical modelling of interaction of the two-dimensional incompressible fluid flow and a flexibly supported airfoil section wit control section. A simplified problem is considered: The flow is modelled by the system of Navier-Stokes equations and the structure motion is described with the aid of nonlinear ordinary differential equations. The time-dependent computational domain is taken into account by the Arbitrary Lagrangian-Eulerian method. Higher order time discretization is considered within the stabilized finite element method. The application of the described method is shown.
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Frequency stabilized semiconductor laser source for high-resolution interferometry
Řeřucha, Šimon ; Hucl, Václav ; Holá, Miroslava ; Čížek, Martin ; Pham, Minh Tuan ; Pravdová, Lenka ; Lazar, Josef ; Číp, Ondřej
We have assembled an experimental iodine stabilized Distributed Bragg Reflector (DBR) diode based laser system lasing at a wavelength that is in a close proximity to the wavelength of a stabilized He-Ne lasers traditionally used for metrological applications (λ=632.9 nm in vacuum). The aim was to verify whether such a system could be used as an alternative to the He-Ne laser while yielding wider optical frequency tuning range, higher output power and high frequency modulation capability. We have measured the basic characteristics of the laser source and then we have compared the performance of the laser system with that of a traditional frequency stabilized He-Ne laser with a series of experimental arrangements similar to those usually found in laser interferometry and displacement metrology applications. The results indicate that DBR diode laser system provides a good laser source for applications in dimensional (nano)metrology since it provides more output power and advanced tunability options than stabilized He-Ne lasers while maintaining fundamental requirements such as the frequency stability, coherence length and also a defined traceability.\n\n
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Subspace Modeling of Prosodic Features for Speaker Verification
Kockmann, Marcel ; Kenny, Patrick (referee) ; Nöth, Elmar (referee) ; Černocký, Jan (advisor)
Předložená disertační práce se zabývá ověřováním mluvčího pomocí prozodických příznaků zahrnujících hodnoty základního tónu, energie a délek řečových úseků. Studovali jsme dvě rozdílné techniky pro parametrizaci: první vede k dobře definované sadě menšího počtu příznaků, druhá k vysoko-dimenzionální sadě heterogenních prozodických příznaků. První část práce se věnuje vývoji příznaků reprezentujících prozodické kontury, zde jsme vyvinuli a ověřili několik modelovacích technik, s důrazem na modelování v reprezentativních podprostorech. Druhá část práce se zaměřuje na nové pod-prostorové modelovací techniky pro heterogenní prozodické parametry s velkou dimenzionalitou. Model je teoreticky odvozen a experimentálně ověřen na oficiálních datech z NIST evaluací ověřování mluvčího (NIST Speaker Recognition Evaluation). Ve srovnání s ostatními současnými prozodickými jsme dosáhli podstatně lepších výsledků. Na konci práce presentujeme také novou techniku pro elegantní kombinaci dvou prozodických systémů. Tato technika může být použita rovněž pro fúzi prozodického systému se standardním přesným cepstrálním systémem, což vede k dalšímu podstatnému zvýšení úspěšnosti verifikace.
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Local characterization of electronic devices
Müller, Pavel ; Škarvada, Pavel (referee) ; Tománek, Pavel (advisor)
The development of micro and nanoelectronics and nanophotonics needs novel characterization techniques to ensure higher quality of designed devices. The thesis describes a use of Scanning Near-field Optical Microscopy (SNOM) in dimensional control and in local investigation of diverse physical parameters. As example of its potential, the correlation between object topography and reflection measurement of capacitors is shown.
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Comparison of competences and skills of higher education graduates with expectations of their first destination employers on Cambodian and Vietnamese labour market
Brtníková, Petra ; Slavík, Milan (advisor)
The agricultural sector in Cambodia and Vietnam continues playing important role in supporting national economic growth and food security. Governments together with range of local and international non-profit organisations work on crosscutting topics of development, particularly in the agriculturally profuse provinces. It creates a number of job opportunities for skilled labour. This research aimed to identify the skills and competences of higher education graduates who participated in the Erasmus Mundus exchage programme in europe in agriculture and related life sciences. It highlights the need to adopt skills and competences that graduates acquired during studies in Europe to demands of the labour market in Cambodia and Vietnam. To conduct this study, two-dimensional research was chosen. It combined quantitative survey among Erasmus Mundus alumni from Cambodia and Vietnam who participated in one of agriculture-related programmes in Europe between 2004 and 2013. Qualitative approach was facilitated using semi-structured interviews and focus group discussions with employers/HR managers and key informants from related NGOs, public and private institutions.
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Numerical Analysis of the Thickness Influence on the Stress Field at Crack Tip for Different Poisson´s Ratios
Seitl, Stanislav ; Hanzlovský, Radovan ; Fernandez, C.
The influence of in- and out- of plane constraints on the behaviour of cracks under mode- I loading condition is studied. The independence of the stress intensity tensor structure, with respect to the specimen thickness B shows that under loss of constraint conditions higher order tensor members of the Williams expansion must be considered to characterize the singular stress field, and to explain the increasing apparent fracture toughness resulting experimentally for decreasing specimen thickness. A numerical study of the effect of Poisson’s ratio on stationary mode I crack tip fields is presented in the contribution. Finite element calculations for two-dimensional (v =0) and three-dimensional bodies are performed and compared. Further, the stress intensity tensor K, and the elastic txx and tzz components of the tij constraint tensor in the middle of a three-dimensional crack front are determined using direct methods for the same level of loading.
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Influence of masification of higher education on graduates' employment
Voříšek, Petr ; Kuchař, Pavel (referee) ; Mudd, Dana (advisor)
The thesis focuses on the transformation processes of tertiary education and aims to provide recommendations for its progress in the Czech Republic. At first, changes of the majority of systems tertiary education in the European countries in the last fifty years are introduced to the reader. This includes the formalized effort for unification of education policies in the sphere of tertiary education, so called "Bologna Process". The paper consequently describes in detail the progress of the higher education in the Czech Republic in the last twenty years, above all in relation to demographic changes in the population, and offers the projection of its expected development. Findings from the first chapters are summarized and supplied by the recommendations of the OECD examiners. The crucial recommendations of OECD examiners - monitoring of the graduates employability and monitoring of the quality of higher education study programmes - are targeted in the second part of the text. Based on the international survey of higher education graduates as well as on the analysis of university rankings' weaknesses, the author constructs the two dimensional indicator of the quality of graduates. The first dimension takes into account particularly the ability of graduates to successfully come across the employment market...
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Numerical simulation of the effect of stiffness of lamina propria on the self-sustained oscillation of the vocal folds
Hájek, P. ; Švancara, P. ; Horáček, Jaromír ; Švec, J. G.
A two-dimensional (2D) finite element (FE) model of the fluid-structure-acoustic interaction during selfsustained oscillation of the human vocal folds (VF) is presented in this paper. The aim is to analyze the effect of stiffness of lamina propria on VF vibrations. Such stiffness change can be caused by some VF pathologies. The developed FE model consists of the FE models of the VF, trachea and a simplified human vocal tract. The vocal tract model shaped for simulation of phonation of Czech vowel [a:] was created by converting data from the magnetic resonance images (MRI). The developed FE model includes VF contact, large deformations of the VF tissue, fluid-structure interaction (FSI), moving boundary of the fluid mesh (Arbitrary Lagrangian-Eulerian (ALE) approach), airflow separation during the glottis closure and solution of unsteady viscous compressible airflow described by the Navier-Stokes equations. The numerical simulations showed that higher values of lamina propria Young's modulus (stiffer lamina propria) result in a decrease of the maximum glottis opening. Stiffer lamina propria also requires the use of higher subglottal pressure to initiate self-sustained vibration of the VF.
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Structural study of metal-CeO2/Cu(111) model systems by RHEED
Beran, Jan ; Mašek, Karel (advisor) ; Jiříček, Petr (referee)
The cerium oxide was deposited by reactive vacuum evaporation on the (111) surface of copper single-crystal in oxygen atmosphere at constant substrate temperatures of 25řC, 300řC and 450řC and at increasing temperature from 25řC to 450řC. In each case, the cerium oxide grew epitaxially with the (111) plane parallel to the substrate. The lattice parameter of the oxide increased up to the value of 5,28 during the deposition. At increasing temperature the growth of additional three-dimensional domains with tetrafold symmetry and (100) plane parallel to the surface was observed. Lattice parameter of these domains exhibited the value of 5,36 in the direction parallel to the surface. These domains were also observed by STM. The palladium grew on the cerium oxide surface in form of epitaxial islands having (111) epitaxial plane parallel to the substrate surface. The palladium deposition resulted in the partial reduction of the oxide layer. The reduction was caused by the interaction of the palladium and oxygen atoms leading to the formation of PdO phase. This feature became more pronounced during annealing at 300řC. Annealing at higher temperatures led to coalescence of the palladium islands and thermal induced decomposition of the palladium oxide.
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