National Repository of Grey Literature 207 records found  previous11 - 20nextend  jump to record: Search took 0.01 seconds. 
On Harmonic Content of the Wake Behind a Circular Cylinder
Uruba, Václav ; Procházka, Pavel P.
The wake behind cylinder of circular cross-section is subjected to detailed analysis from the point of view harmonic content. The basic, fundamental frequency could be linked to well-known Bénard-von Kámán vortex street, it is called Strouhal frequency very often. However higher harmonics of 2nd and 3rd order have been detected, as well as important inharmonic partials. The topologies of the velocity flow-field corresponding to the harmonic is to be shown.
Identification of the blade tip possition and measurement techniques using the BTT method
Maturkanič, Dušan ; Procházka, Pavel ; Hodboď, Robert ; Mekhalfia, Mohammed Lamine
This paper describes the existing practice in identifying and defining the position of the blade tips and the relevant technique for measuring their vibration during rotation. In connection with the effort to precisely define the position of the vibrating blade, the paper also analysed the possibilities of unambiguous determination of its position. This work creates a parallel branch to signal processing in the complex system of precision measurement and analysis of blade vibration, which was mentioned in previous papers.
Effect of oscillating blade on tonal noise of blade cascade with five NACA 0010 profiles
Šnábl, Pavel ; Pešek, Luděk ; Radolf, Vojtěch ; Antoš, Pavel ; Procházka, Pavel P. ; Prasad, Chandra Shekhar
The airfoil tonal noise is a well known phenomenon which appears on single airfoils in moderate Reynolds numbers at low angles of attack. It can appear on small aircrafts, fans, wind turbines etc. In thispaper, it was observed on a blade cascade consisting of five NACA 0010 profiles placed in a closed rectangular channel with hard walls when for given conditions, i.e. flow velocity and angle of attack, the cascade tunes to one single frequency. During the middle blade oscillation, the single tone splits up to several tones with lower intensity modulated by the excitation frequency. Thus, the oscillation of one blade suppresses the tonal noise generation in the cascade.
Analytical procedures for solving blade vibration using the Blade Tip Timing - theoretical description of the method
Maturkanič, Dušan ; Procházka, Pavel ; Mekhalfia, Mohammed Lamine
The report focuses on an analytical approach to solving the problem of turbine and compressor blade vibration using the Blade Tip Timing method. The report contains a description of the new method with defined solution requirements. Verification of the method was performed by simulation, where the correct input data was used in the analysis of the reliability of the method when the calculation was repeated at a sufficiently large number of revolutions, while in the accuracy analysis, intentionally distorted input data was used. The report also includes connection to the results of frequency and amplitude calculation for fluctuating speeds obtained by the deterministic method, which was described in previous works aimed at achieving a precise calculation of the frequency and amplitude of blade vibration in real conditions.
Vibration mode shape extraction of bladed disk
Mekhalfia, Mohammed Lamine ; Procházka, Pavel ; Tchawou Tchuisseu, Eder Batista ; Maturkanič, Dušan ; Hodboď, Robert
This research paper deals with the experimental protocol followed to visualize the vibration mode shape of an aero-engine bladed disk. This study is based on a comparison between the numerical results obtained through Finite element methods (FEM) using ANSYS software and experimentally using the laser Doppler vibrometer. Therefore the bladed disk was transformed into a 3D virtual environment and structural analysis was performed. The results demonstrate a match between the numerical and the experimental one, this match offers the possibility for using the model for future studies.
Two-way fluid structure interaction study of aero-engine compressor blade vibration under air excitation
Mekhalfia, Mohammed Lamine ; Procházka, Pavel ; Tchawou Tchuisseu, Eder Batista ; Maturkanič, Dušan ; Hodboď, Robert
In this paper, we provide a numerical method via FEM software (ANSYS) using two-way Fluid-Structure Interaction (FSI) solver to estimate the blade’s vibration where the force used to excitation is a continuous air jet. This will help to provide data to diagnostic blade condition and health monitoring and a bridge toward a precise study of the blade’s dynamic under rotation and the estimation of blade’s displacement to define the amplitude and the frequency that occurs under different types of excitation which is a pillar for the process of machine condition and health monitoring.
Torque and Flow Field Optical Measurements of The Single Blade Under Stall Flutter
Procházka, Pavel P. ; Uruba, Václav ; Šnábl, Pavel
The single blade NACA0010 was exposed to the incoming flow inside a channel with rectangular cross-section. The blade was investigated for three different working regimes. The first configuration was for fixed blade. The second regime was for fluttering blade due to flow instabilities and the last one was performed for blade under force excitation. The flow field was measured using Particle Image Velocimetry. A force transducer and a small rotary encoder were used to evaluate the force ratios.
Metal-organic interface for effective charge transfer
Mrhačová, Petra ; Průša, Stanislav (referee) ; Procházka, Pavel (advisor)
This bachelor thesis deals with the analysis of benzene-1,3,5-tricarboxylic acid (TMA) molecules on a silver crystal with (111) surface termination. After the deposition of the molecules on the substrate, a fully protonated layer ( phase) is formed. Further substrate annealing induces a deprotonation process, which leads to the formation of another and phases. The different arrangements of the molecules were studied in ultra-high vacuum conditions by low-energy electron microscope (LEEM), scanning tunneling microscope (STM), and by low-energy electron diffraction (LEED). The application potential of these layers is discussed.
The attitude of slovak evangelical churches to liturgy
Jurčová, Mária ; Procházka, Pavel (advisor) ; Liguš, Ján (referee)
JURČOVÁ, Mária. The attitude of Slovak Evangelical Churches to Liturgy. [Master thesis] / Mária Jurčová. - Charles Univerzity in Prague. Hussite Theological Faculty; - Supervisor: prof. ThDr. Pavel Procházka, PhD. - Degree: Master. - Prague : HTF UK, 2011. 83 p. This Master thesis "The attitude of Slovak Evangelical Churches to Liturgy" deals with current shape of Sunday worship in Slovak evangelical churches. This study shows liturgical tension which generates our changing culture and also asks a question how can we form liturgy in this new culture. The purpose of this thesis is to describe current situation and liturgy in Slovak evangelical churches and outline assumes of liturgical renewal in changing times. The first chapter is short introduction to the terminology. The second chapter focuses on the New Testament point of view regarding questions of the liturgy. The third chapter deal with new cultural transformation in the world and in Slovakia and is also focused on impact of these changes on evangelical liturgy. New culture, known as postmodernism, shows new styles of liturgy. The fourth chapter brings empirical results of evangelical liturgy research. This thesis wants to contribute for present discussion about liturgical renewal in evangelical churches. Keywords: Liturgy - Worship -...
Members of individual types of business company
Procházka, Pavel ; Horáček, Tomáš (advisor) ; Eichlerová, Kateřina (referee)
95 12. 3 RESUMÉ Members of Several Forms of Business Companies. This paper aims to find the difference between the status of the members of the several forms of Czech business companies. This paper is about rights and obligations of the members of Czech business companies which are an unlimited partnership (a general commercial partnership), a limited partnership, a limited liability company and joint stock company. This paper is also about rights and obligations of the members of business companies which are supranational and governed by the law of European communities. These European supranational forms are European economic interest grouping and European company (SE). In the beginning I give a brief overview of the general rights and obligations arising from the membership of natural or corporate entities of business companies. The rights and obligations of the members of business companies depending on whether nature of the business company is so called personal or capital. The nature of the unlimited partnership, particularly the limited partnership and the European economic interest grouping is personal. The nature of the limited liability company, the joint stock company and European company (SE) is capital. I try to explain the differences among above mentioned two groups of business companies The...

National Repository of Grey Literature : 207 records found   previous11 - 20nextend  jump to record:
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