National Repository of Grey Literature 26 records found  1 - 10nextend  jump to record: Search took 0.02 seconds. 
Local velocity scaling in upward flow to tooth impeller in a fully turbulent region
Šulc, R. ; Ditl, P. ; Fořt, I. ; Jašíková, D. ; Kotek, M. ; Kopecký, V. ; Kysela, Bohuš
The hydrodynamics and flow field were measured in an agitated vessel using 2-D Time Resolved Particle Image Velocimetry (2-D TR PIV). The experiments were carried out in a fully baffled cylindrical flat bottom vessel 400 mm in inner diameter agitated by a tooth impeller 133 mm in diameter. Distilled water was used as the agitated liquid. The velocity fields were investigated in the upward flow to the impeller for three impeller rotation speeds – 300 rpm, 500 rpm and 700 rpm, corresponding to a Reynolds number in the range 94 000 < Re < 221 000. This means that fully-developed turbulent flow was reached. This Re range secures the fully-developed turbulent flow in an agitated liquid. In accordance with the theory of mixing, the dimensionless mean and fluctuation velocities in the measured directions were found to be constant and independent of the impeller Reynolds number. On the basis of the test results the spatial distributions of dimensionless velocities were calculated. The axial turbulence intensity was found to be in the majority in the range from 0.4 to 0.7, which corresponds to the middle level of turbulence intensity.
Droplets breakage in flow conditions of an agitated tank
Kysela, Bohuš ; Konfršt, Jiří ; Chára, Zdeněk ; Šulc, R. ; Kotek, M.
Production of two immiscible liquid dispersions used in chemical or metallurgical industry is usually performed by a mixing process. The droplets of secondary liquid are predominantly dispersed by the shear flow forces to the primary liquid. It is well known, that the real droplet size distribution is limited by the physical properties of both liquids, the acting forces and residence time. This phenomenon is investigated experimentally or numerically simulated by several methods. In this study, the simplified mixing test case was studied. The single droplet dispergation was simulated using finite volume method and multiphase VOF (Volume-of-Fluid) model. The capability of the local remeshing method was investigated. The increase of calculation performance and the phases mass imbalance during automatic mesh refinement is summarized.
Measurement of drop size distribution time rate for liquid-liquid dispersion using IPI method
Jašíková, D. ; Kotek, M. ; Kysela, Bohuš ; Šulc, R. ; Kopecký, V.
The liquid-liquid dispersion properties are studied mainly by image analysis (IA) and Interferometric Particle Imaging (IPI). Drop sizes will be investigated in dilute dispersion since in this case the break up phenomena is the dominating and is not affected by phase fraction. Characteristics of the size distribution and the evolution of two liquid-liquid phase’s disintegration were studied. The IPI method was used for subsequent detailed study of the disintegrated droplets. We compared two liquids: Rhodosil Oil 47V50, and Silicone Oil AP1000 under stirrer rate of 540 rpm, and 760 rpm. The experiment run in the scaled model of agitated tank with Rushton turbine.
Turbulence characteristics scaling in Rushton turbine impeller discharge flow: effect of PIV system setup
Šulc, R. ; Ditl, P. ; Fořt, I. ; Jašíková, D. ; Kotek, M. ; Kopecký, V. ; Kysela, Bohuš
Study of mechanism of turbulent energy dissipation rate in the impeller discharge stream from a standard Rushhton turbine impeler in a model cylyndrical vessel with radial baffles.
Droplet size measurement in two-phase system
Kysela, Bohuš ; Konfršt, Jiří ; Chára, Zdeněk ; Kotek, M. ; Šulc, R.
The in-situ measurement method of droplet size in an agitated vessel based on droplet visualisation and image analysis were developed. The image analysis was enhanced by the finding edges algorithm and circularity analysis. The proposed method was validated by the measurements of precise solid particles and used for liquid-liquid mesurements in an agitated vessel.
Employee's satisfaction and loyalty in the marketing agency
Kotek, Martin ; Rymeš, Milan (advisor) ; Bahbouh, Radvan (referee)
1 Abstract: This paper brings a specific look into the world of marketing agencies working in market research through the job satisfaction and employee loyalty constructs. In the theoretical framework is presented conceptual and definitional problem of job satisfaction, which is consequently supplied by other theories like work engagement, work commitment or employee loyalty. Author's goal is to describe these theoretical concepts as interdependent, but simultaneously able to work separately and with support of other factors, which lead to their increasing or decreasing. In the empirical part of the framework are information used in praxis through the concrete marketing agency working in market research. Work environment is presented like dynamical example of modern company with explanation how works these aspects of job satisfaction and loyalty right there. Empirical research is realized with help of well-known methodological instruments used for measurement of these constructs to analyse and describe work environment of this company with a goal to identify the level of different aspects of job satisfaction and employee loyalty. Keywords: Job satisfaction, employee loyalty, work motivation, marketing agency
The minimum record time for PIV measurement in a vessel agitated by a Rushton turbine
Šulc, R. ; Ditl, P. ; Fořt, I. ; Jašíková, D. ; Kotek, M. ; Kopecký, V. ; Kysela, Bohuš
In PIV studies published in the literature focusing on the investigation of the flow field in an agitated vessel the record time is ranging from the tenths and the units of seconds. The aim of this work was to determine minimum record time for PIV measurement in a vessel agitated by a Rushton turbine that is necessary to obtain relevant results of velocity field. The velocity fields were measured in a fully baffled cylindrical flat bottom vessel 400 mm in inner diameter agitated by a Rushton turbine 133 mm in diameter using 2-D Time Resolved Particle Image Velocimetry in the impeller Reynolds number range from 50 000 to 189 000. This Re range secures the fully-developed turbulent flow of agitated liquid. Three liquids of different viscosities were used as the agitated liquid. On the basis of the analysis of the radial and axial components of the mean- and fluctuation velocities measured outside the impeller region it was found that dimensionless minimum record time is independent of impeller Reynolds number and is equalled N. t(Rmin) = 103 +/- 19.
Local velocity scaling in T400 vessel agitated by Rushton turbine in a fully turbulent region
Šulc, R. ; Ditl, P. ; Fořt, I. ; Jašíková, D. ; Kotek, M. ; Kopecký, V. ; Kysela, Bohuš
The hydrodynamics and flow field were measured in an agitated vessel using 2-D Time Resolved Particle Image Velocimetry (2-D TR PIV). The experiments were carried out in a fully baffled cylindrical flat bottom vessel 400 mm in inner diameter agitated by a Rushton turbine 133 mm in diameter. The velocity fields were measured in the zone in upward flow to the impeller for impeller rotation speeds from 300 rpm to 850 rpm and three liquids of different viscosities (i.e. (i) distilled water, ii) a 28% vol. aqueous solution of glycol, and iii) a 43% vol. aqueous solution of glycol), corresponding to the impeller Reynolds number in the range 50 000 < Re < 189 000. This Re range secures the fully-developed turbulent flow of agitated liquid. In accordance with the theory of mixing, the dimensionless mean and fluctuation velocities in the measured directions were found to be constant and independent of the impeller Reynolds number. On the basis of the test results the spatial distributions of dimensionless velocities were calculated. The axial turbulence intensity was found to be in the majority in the range from 0.388 to 0.540, which corresponds to the high level of turbulence intensity.
Rare Disasters and Asset Pricing Puzzles
Kotek, Martin ; Maršál, Aleš (advisor) ; Korbel, Václav (referee)
The impact of rare disasters on equity premium and term premium in a New Keynesian DSGE model is explored in the thesis. Andreasen's (2012) model with Epstein-Zin preferences, bonds and a rare disaster shock in total factor productivity process is extended by a variable capital stock and an equity-type asset. We find that the variable capital significantly changes behavior of the model, capital depreciation must be substantially increased to counter the effect of variable capital and stochastic mean of inflation increases. The model calibrated to the US economy and a high risk aversion generates 10-year term premium of 90 basis points, rare disasters increase the premium only by 3 basis points. The equity premium is 163 basis points and rare disasters increase it also only by 3 basis points. The model with a low coefficient of relative risk aversion of 5.5 generates negative risk premia. Rare disasters increase the risk premia by mere 4 basis points in comparison to a model with i.i.d. shocks. Powered by TCPDF (www.tcpdf.org)

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See also: similar author names
6 KOTEK, Martin
6 Kotek, Martin
1 Kotek, Milan
2 Kotek, Miloslav
1 Kotek, Miroslav
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