National Repository of Grey Literature 164 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Manufacturing of pin with flange
Procházka, Pavel ; Řiháček, Jan (referee) ; Podaný, Kamil (advisor)
The bachelor thesis is focused on the design of the towing hitch, which is used in the tractor. The component will be the production of a die forging technology made of low-alloy steel 13 242. The material is supplied as hot-rolled bars with a diameter of 60 mm and a length of 6 000 mm. The size of the production series has been set at 25,000 pieces per year. Due to the issue and the size of the forging, the component will be made on a power hammer. The machine Šmeral KHZ 8A, appears to be a suitable machine as the forging work was calculated at 89 kJ. The technical - economic evaluation takes into account material costs, which amount to 1,364,271 CZK. The die is made of tool steel 19 663, its purchase price is 73 000 CZK.
Fabrication and characterization of two-dimensional heterostructures
Majerová, Irena ; Švec, Martin (referee) ; Procházka, Pavel (advisor)
After the experimental discovery of graphene at the beginning of the 21st century, many other interesting 2D materials have been discovered. However, the electrical and optical properties of these layers are greatly influenced by the composition and quality of the surrounding materials. In order to preserve the exceptional properties of thin films, attention has gradually been drawn to heterostructures from 2D composite materials. This thesis describes the preparation and characterization of heterostructures composed of graphene and hexagonal boron nitride. In addition, a specific focus will be placed on optimizing the production process of heterostructures by the dry thin film transfer process, prepared by micromechanical exfoliation. Characterization and quality of prepared layers are controlled by Raman spectroscopy, while morphology is examined by atomic force microscope (AFM). Furthermore, the electrical properties of the graphene-hBN device are discussed and the charge carrier of the graphene field-effect transistor is measured.
Substrate-controlled nucleation of the magnetic phase transition in nanostructures
Hajduček, Jan ; Procházka, Pavel (referee) ; Uhlíř, Vojtěch (advisor)
Properties of the phase transition in iron-rhodium (FeRh) from the antiferromagnetic (AF) to ferromagnetic phase (FM) are largely affected by lattice defects in FeRh. Epitaxial layers of FeRh are grown on monocrystalline MgO (001) substrates. Surface atomic terraces of the substrate can induce defects in epitaxial layers and modify electronic and magnetic properties. In this thesis the effect of surface atomic terraces on the width and the hysteresis of the metamagnetic phase transition in FeRh thin layers and nanostructures is studied. The amount and character of defects in FeRh are also affected by mutual orientation of terraces and FeRh nanowires, which changes the number of discrete jumps in FM-AF transition. The nanowires have been fabricated by electron-beam lithography. FM domains in in FeRh have been observed by magnetic force microscopy and electrical transport properties of differently oriented nanowires have been studied by 2-probe measurements. Higher density of surface atomic terraces significantly increases the number of discrete jumps in the FM-AF transition.
Study of Behaviour of Paramagnetic Molecules on Surfaces
Bouček, Martin ; Procházka, Pavel (referee) ; Hrubý, Jakub (advisor)
This thesis deals with behaviour of paramagnetic molecules of copper(II) pthalocyanine (CuPc), hemin and bis(dibenzoylmethane)copper(II) ([Cu(dbm)2]) on surfaces of glass and polycrystalline gold. Additionally the [Cu(dbm)2] is studied on graphene surface. Molecules are deposited on substrates via wet chemistry methods. They are studied after deposition with atomic force microscopy (AFM), electron paramagnetic resonance (EPR), scanning electron microskopy (SEM) and X-ray photoemission spectroscopy (XPS).
Assessing Quality of Boundary Layer Flows With the Diagnostic Plot
Jurčáková, Klára ; Procházka, Pavel P. ; Kellnerová, Radka
We experimentally investigated turbulent boundary layers over 4 rough surfaces and 1 smooth surface by particle image velocimetry for a range a free stream velocities. The obtained mean velocity vertical profiles were universally scaled by roughness length z₀ and friction velocity u*, but both parameters have to be obtained from the fit of the logarithmic or composite velocity pro le to the experimental data. Diagnostic plot, which relates turbulence intensity with the mean velocity showed good collapse of different free stream velocities for each surface. It became fully universal in its modified version when the roughness function was taken into an account. We found that turbulence intensities over our surfaces are higher than any published one and that they dependent on roughness length z₀*.
Large Scale Motions in Turbulent Flows
Kellnerová, Radka ; Jurčáková, Klára ; Procházka, Pavel P.
Quadrant analysis based on the Reynolds decomposition was performed on the data from turbulent boundary layer flows above variously rough surfaces. An estimation of a convective velocity for events significant in terms of momentum flux, and the statistics of a length and amplitude of the individual events, together with their spectral analysis, was performed. Based on the analyses, we were able to detect a few individual sweep and ejection events with a length longer than 6δ, which could be considered as very large scale motions (VLSM). We also identified number of events with a longitudinal dimension equal to approximately 3δ labelled as large scale motions (LSM). The analyses were executed for various Reynolds numbers. The number of detected structures increases with the momentum of the flow.
Structure of the Wake Behind an Airfoil
Uruba, Václav ; Procházka, Pavel P. ; Skála, Vladislav
The wake behind an inclined plate simulating airfoil is to be studied experimentally. The vortical structures are identified eventually. Theirs topology and dynamical behaviour is to be studied in details using the Proper Orthogonal Decomposition method. The stereo time resolved Particle Image Velocimetry technique is used for the experimental research. The vortex trains with oblique orientation and chequered topology have been detected.
Flow in Branched Channel
Uruba, Václav ; Procházka, Pavel P. ; Skála, Vladislav
Flow in a branched channel is investigated experimentally using the PIV method. The branches are issuing from the main cannel perpendicularly, all channels are of rectangular cross-section. The time-mean flow-fields in the main channel and in the branches are studied in details.
Measurement of Turbulence in LP Part of the 1090 MW Steam Turbine
Antoš, Pavel ; Uruba, Václav ; Jonáš, Pavel ; Procházka, Pavel P. ; Skála, Vladislav ; Hoznedl, M. ; Sedlák, K.
The aim of the paper is to demonstrate a use of the hot-wire anemometry for measurement of turbulent fluctuation in a steam turbine. Measurement technique and used methods are presented in the paper. An experimental research was performed in the last stage of LP (lowpressure) part of the 1090 MW steam turbine in nuclear power-plant turbine. The last moving steel blade has a length of 1220 mm. The experiment was carried out by Institute of Thermomechanics of Czech Academy of Science (IT CAS) in cooperation with Doosan Škoda Power s.r.o. (DSPW), the manufacturer of the turbine.
The Experimental Study of Aeroelastic Coupling of the Moveable Blade Grid with the Flow Field at Reynolds Number up to 150 000
Procházka, Pavel P. ; Uruba, Václav ; Pešek, Luděk ; Bula, Vítězslav
This experimental study was conducted to help clarify an aeroelastic coupling in the case of rotational periodic bodies. The blade grid was placed behind the outlet of the blow-down wind tunnel. Three of five blades were constructed to allow vertical position changing by the action of three shakers. Particle Image Velocimetry was used to study the flow field statistical and dynamical parameter. The parameters, whose presence indicates the aeroelastic coupling, are searched.

National Repository of Grey Literature : 164 records found   1 - 10nextend  jump to record:
See also: similar author names
32 Prochazka, Petr
3 Procházka, P.
14 Procházka, Pavel P.
32 Procházka, Petr
2 Procházka, Přemysl
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