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Využití biometrie synuzie dřevin dospělých smrko-bukových porostů k lesnicko-typologické charakteristice jednotek polesí Štoky
Straka, Prokop
Biometric measurements were performed on randomly selected areas, using the ArcMap application in communal forests of Štoky, supplemented with typological and pedological characteristics of the measured areas. Using the Statistica program, the dependence of the microrelief on the height and dominant heights of the stand were compared. The collected statistical data were subsequently evaluated. It was found that only 2 species of wood species are present in the measured areas, namely Norway spruce (Picea abies) and European beech (Fagus sylvatica). Trees have the highest elevation in the leading habitats, and in the middle slope gradients. European beech reaches the highest altitudes on the southern exposition in the measured area, Norway spruce on the western exposition. Furthermore, trees reach the highest heights on wet forest types.
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Use of 3D technology in foundry industry
Straka, Pavel ; Krutiš, Vladimír (referee) ; Pernica, Vítězslav (advisor)
The work is focused on replacing a faulty briefcase handle with an aluminium substitution. The handle is fabricated with the help of reverse engineering, where the handle is scanned with a 3D scanner. With that information, a model copy of the part is made, which is 3Dprinted from PLA and PolyCast materials. These handles are used as expendable models, which are used for casting using an “investment casting” method. Those are made from an AlSi10Mg alloy. Theoretical part deals with additive technologies, which are mostly used for manufacturing of foundry models and moulds. Next, the basic principles of 3Dscanning are described, and the term reverse engineering is also explained.
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Roofing of tribune
Straka, Pavel ; Horáček, Martin (referee) ; Balázs, Ivan (advisor)
The subject of this thesis was to design and assess the load-bearing structure of the grandstand roof at the sports stadium. The ground plan dimensions are 35x70 m. The object will be located in Moravské Budějovice. The construction is made of grade steel S355 and steel fasteners. Assessments were created for 2 variants. Variant A with truss, Variant B with plate girder. The truss variant, which is elaborated in more detail, was evaluated as more advantageous.
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Use of nanofiber filter for air filtration
Straka, Petr ; Hlaváč,, Jaroslav (referee) ; Kabrhel,, Michal (referee) ; Malá, Jitka (advisor)
The doctoral thesis „Using of nanofiber filter for air filtration“ is focused on application of nanofiber filter for air filtration under demanding conditions of water supply facilities. The main aim of the filter application is to decrease the secondary contamination of the indoor environment of the water accumulation tanks. The nanofiber filters are distinguished by high filtration efficiency of pollutants, dust particles and organic impurities. The contaminants don´t have to be unhealthy but they can be used for spore and microorganisms delivery to the system. They are served frequently as a reproduction substrate of microorganisms. All these factors negatively affect the water quality. The research includes formation of suitable testing methodology, pilot unit construction and operation, short-term testing and evaluation of nanofiber filters and commonly used filters and long term testing and verification of nanofiber filter attributes and quality. Furthermore the filter´s characteristics and filtration efficiency for characteristic pollutants were evaluated. Short-term and long-term experimental testing proved suitability of nanofiber filters use in water supply facilities. Interception of reported pollution indicators was reported on similar or higher level for application of nanofiber filter than for application of commonly used filter. Measured values of higher pressure difference of nanofiber filter were indicated as still adequate for use in water supply facilities. No operation difficulties, failures neither filter´s damage were reported during testing of nanofiber filters.
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The Roof Structure of Sport Building
Straka, Pavel ; Šmak, Milan (referee) ; Buchta, Stanislav (advisor)
The aim of the bachelor thesis is to design and assess wooden framework of roofing of multipurpose sport hall. The object is located in Moravské Budějovice. Ground plan dimensions are 40 m x 60 m and height is 10,7 m. The main load-bearing elements are full length beams, which statically acts as a double-jointed arches. The design is made of glued laminated wood, solid wood and connecting steel elements. The stability of beams is secured by purlins and transverse stiffeners. The substructure is designed with anchor blocks made of concrete situated on the foundation strips. The front walls are secured by columns and braces.
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Simulation of Transonic Flow Through a Mid-span Turbine Blade Cascade for Various Mach Numbers
Straka, P. ; Příhoda, Jaromír ; Fenderl, D.
The contribution deals with the numerical simulation of 2D transonic flow through a mid-span turbine blade cascade for several Mach numbers by means of the EARSM turbulence model of Hellsten (2004) connected with the algebraic bypass transition model of Straka and Příhoda (2014). Both models are implemented into an in-house numerical code based on the finite volume method. The gamma-transition model of Menter et al. (2015) with SST turbulence model accessible in the commercial code ANSYS Fluent was used for the comparison.
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Modelling of Flow in Linear Blade Cascade with Thick Trailing Edge at a Lower Reynolds Number
Straka, P. ; Příhoda, Jaromír
In the paper there are compared results of numerical simulation of compressible turbulent flow through a low-pressure turbine blade cascade with relatively thick trailing edges for various physical models. Steady, unsteady, fully turbulent, transitional, two-dimensional and three-dimensional models are compared. Results show that: a) steady simulation gives an incorrect prediction of the boundary layer development, b) two-dimensional unsteady simulation leads to inaccurate prediction of the far wake development and c) only three-dimensional unsteady transitional simulation gives sufficiently accurate prediction. Results of numerical simulations are compared with the experimental data.
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Simulation of Transonic Flow Through a Mid-Span Turbine Blade Cascade with the Separation-Induced Transition
Straka, P. ; Příhoda, Jaromír ; Fenderl, D.
The paper deals with the numerical simulation of the transonic flow through a mid-span turbine blade cascade by means of an in-house code based on the EARSM turbulence model of Hellsten [1] completed by the algebraic transition model of Straka and Příhoda [2]. The simulation using the transition model of Langtry and Menter [3] and Menter et al. [4] implemented in the commercial code ANSYS Fluent was used for the comparison. Simulations were carried out for the transonic regime close to the nominal regime. The flow separation on the suction side of the blade is caused by the interaction of the reflected shock wave with the boundary layer. The attention was focused on the modelling of the transition in the separated flow especially on the modelling of the length of the transition region. Numerical results were compared with experimental results.
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Material and Energy Utilization of Dry Stabilized Sewage Sludge – Production of Biochar by Medium-Temperature Slow Pyrolysis.
Pohořelý, Michael ; Moško, Jaroslav ; Zach, Boleslav ; Šyc, Michal ; Václavková, Šárka ; Jeremiáš, Michal ; Svoboda, Karel ; Skoblia, S. ; Beňo, Z. ; Brynda, J. ; Trakal, L. ; Straka, Pavel ; Bičáková, Olga ; Innemanová, P.
The article summarizes the main properties of biochar produced by medium-temperature slow pyrolysis of anaerobically stabilized sewage sludge.
Fulltext: content.csg -  PDF
Plný tet: SKMBT_C22017071208540 - PDF
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Modulation of time dispersion of femtosecond laser pulses
Vyhlídka, Štěpán ; Straka, Petr (advisor) ; Ostatnický, Tomáš (referee)
In the presented thesis the topic of femtosecond pulse dispersion and methods of characterizing pulse profile are briefly introduced. Then, a functionality of a spatial light modulator is described. The spatial light modulator was used in an experimental scheme called the pulse shaper, which allowed independent amplitude and phase modulation of pulses. Duration and dispersion of pulses was measured by two methods called MIIPS and PICASO. MIIPS was also used for a reconstruction of a spectral phase of pulses. The autocorrelator was constructed on a design of the Mach-Zehnder interferometer. The duration of the shortest measured pulse (13.3 ± 0.5) fs was retrieved from measured interferometric autocorrelations by PICASO. Furthermore, theoretical dependence of pulse duration on the group delay dispersion was confirmed for pulses shorter than 120 fs. The group velocity dispersion was measured for fused silica windows and for a pair of diffraction gratings in the pulse shaper. Both values confirmed theoretical expectations.
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