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Visualization of synthetic jets at higher stokes numbers
Broučková, Zuzana ; Trávníček, Zdeněk ; Šafařík, Pavel
Visualization of synthetic jets at higher Stokes numbers (S = 90 and 127) by the phase-locked smoke-wire technique is presented and discussed. The working fluid is air. The Reynolds numbers are quantified using hot-wire anemometry. Although our method of visualization essentially provides only qualitative results, the present study also demonstrates some quantitative results, namely the behavior of the zero-net-mass-flux jet near its critical stage. Visualization of the sub-critical stage is also shown.
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The effect of investment in tertiary education on gross wages in the region Prague
Diessner, Daniel ; Chytil, Zdeněk (advisor) ; Babin, Jan (referee)
The aim of this work is to determine whether and how higher education affects gross wages. The theoretical part focuses on the theory of human capital, especially investment in education. The theory posits that a higher investment in human capital leads to higher yield, higher wages. The validity of this concept will be tested on the group of respondents who entered the labour market at the turn of millennium. Concentration of candidates with tertiary education in this period has risen considerably, which could cause an imbalance in the labour market. The practical part is based on the work of Mincer (1974). I used Mincer Earnings Function as a basis to build regression model. Partial aim is to prove the declining rate of return on investment in tertiary education using Mincer Equation.
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Tax and legal issues of real-estate business in Austria
Banctel, Kristýna ; Filipová, Vladimíra (advisor) ; Drozen, František (referee)
The purpose of this study is to compare tax and civil-law issues concerning property business in Austria and in Czech Republic in 2016 and to investigate the efficiency of the current legislation against the real estate bubble. The theoretical part of this study contains selected demographic and price statistics concerning real estate in both countries and focuses on the description of the existing law currently in effect in both compared countries. The practical part analyses tax and transactions costs that concern property trading and a comparison of possibilities of amortisations and rentability of a rented flat in both countries.
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The way of consumerism in the interwar Czechoslovakia nn the example of consumption of coffee, cocoa, chocolate and tea.
Syrová, Tereza ; Jakubec, Ivan (advisor) ; Jančík, Drahomír (referee) ; Štemberk, Jan (referee)
Dissertation thesis discusses the consumption of cocoa, coffee, tea and chocolate in the interwar period in the Czechoslovakia. On the basis of statistical data and examination of archival sources comes with the definition of the middle classes of the population, which those commodities consumed. The thesis shows the distribution of consumption of commodities based on the survey in blue-collar and white-collar families. Furthermore provides insight into the lives of families, distribution of their spending and the size of income. It refers to the representation of cocoa, coffee, tea and chocolate in the consumer basket and shows the elasticity of the mentioned commodities. For the central part of the research of the dissertation thesis chose the Czech territory only, because here were without difficulty accessible data sources. The Dissertation thesis clarifies the causes of consuming cocoa, coffee, tea and chocolate and concludes that each was consumed from another purpose, which resulted status of these commodities. Tea consumption has been designed especially for the higher classes of the population, chocolate bought mostly white-collar family, but over twenties speared consumption of chocolate products also among the middle and lower classes into the population. The chocolate products were subject to early 20s of the luxury tax. Cocoa was used in connection with cooking and baking, but families didnt use this product frequently. Coffee drank all layers of the population, but consumption was based on the social status of the consumer. Very frequently families consume rye coffee and chicory coffee. Dissertation thesis also highlights the regional differences between the classes, which were further intensified. Thesis examines in detail the amount of the duties of the commodity, which in the interwar period varied widely, and concludes that the duty to disproportionately increase the price of products and made it impossible for consumers to buy more of cocoa, coffee, tea and chocolate.
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Differences between men and women in the Czech labour market
Stroukal, Dominik ; Kadeřábková, Božena (advisor) ; Pavelka, Tomáš (referee) ; Němec, Otakar (referee)
This thesis consists of five articles that apply current world research on labor economics at the Czech Republic and confirms the significant differences between men and women in this market. It shows that gender has a significant influence on the preference on the labor market and, consequently, on employment and health. First, the thesis shows that preferences are relevant determinant of career and then we study the difference in preference of salary for men and women. Subsequently it shows that gender plays a significant role in explaining the relationship between homeownership, and unemployment, as well as unemployment and health. The first chapter was able to demonstrate that the preference for a career has a positive influence on the choice of career. The influence of higher education on prioritizing career proved to be positive and significant. Probability of a career choice is reduced by the presence of children, however, is not dependent on their number, which is contrary to the theory of preferences. The second chapter shows that Czech women prefer more non-monetary rewards than men. It has also been shown that people with university education are same in the preferences of non-monetary rewards regardless of the gender of the respondents, however, compared to the world's research, the Czech higher education increases this preference. It turned out that women prefer risk less than men. The third chapter demonstrates that although the housing market undermines labor mobility and employment in the Czech Republic at the regional level, therefore, that in regions with a higher rate of home ownership is higher unemployment, at the individual level, the owners of housing are unemployed are less likely. The estimates are significantly different for men and women. Men living in owner-occupied housing have a higher likelihood of employment than women. At regional level, however, this thesis shows that the high rate of home ownership increases unemployment for both men and women, in the long run only to women. The fourth chapter showed that men transition to homeownership reduces the likelihood of unemployment next year. For women, this relationship has proved to be insignificant. In addition, as insignificant showed the opposite relationship, the transition from unemployment to the newly acquired home ownership. The last chapter shows that the change in the working status to unemployment will increase in the future probability of worse health. Influence in less than two years, however, proved to be significant. An important conclusion is that men have a significantly stronger relationship between health and unemployment than women.
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INFLUENCE OF LASER CUTTING AND PUNCHING ON MAGNETIC PROPERTIES\nOF ELECTRICAL STEEL M470-50A
Bulín, Tomáš ; Švábenská, Eva ; Hapla, Miroslav ; Ondrůšek, Č. ; Schneeweiss, Oldřich
Electrical steel M470-50A belongs to the most often used materials in electrical machines. Due to this fact, it is desirable to know the magnetic parameters after processing raw sheets into the required shape. Basic parameters of mechanical, electrical, and magnetic properties of the sheets are usually obtained from the producer but the magnetic properties are changing in dependence on additional machining processes. The aim of this study is to describe changes in parameters of magnetic behavior after punching, laser and spark cutting of the original sheets. The basic information of structure was obtained by optical and scanning electron microscopy. The magnetic parameters were acquired from the measuring of magnetic hysteresis loops in dependence on saturation fields and frequencies. The results are discussed from the point of view of applied\ncutting technology with the aim to obtain the best magnetic parameters and consequently a higher efficiency of the final product. Results can be used as input parameters in simulation of the electrical machine.
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The tax system reduces motivation to return to work among mothers with young children: recommendations and evaluation
Šatava, Jiří
In the Czech Republic, the overall taxation of work, i.e individuals' income tax together with social security and health insurance contributions, places a heavy burden even on the relatively low earnings of so-called second earners in households, i.e. partners with lower earnings. These peoples' work activity is, however, generally very sensitive to the level of taxation. A large group of these earners is made up of mothers with young children. Mothers who are the second earner in their household are subject to a participation tax rate (PTR) up to 30 % higher than their partners, and yet a higher PTR results in lower motivation to work. Women with children and low earning potential are subjected to the highest PTRs in comparison with their partners.
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Sorption and Stabilization of Metals/Mettalloids by Innovative Synthesized Sorbent Amochar.
Ouředníček, P. ; Trakal, L. ; Komárek, M. ; Pohořelý, Michael
Remediation of contaminated soil which is based on stabilization and immobilization of potential\nhazardous substance by sorption materials has been studied intensively nowadays. Biochar – activated organic carbon belongs to this group of stabilizing agents which can adsorb wide range of contaminants, including metals/metalloids. Surface area of the biochars is quite large in general and functional groups (e.g. COO–) can form chelates or alkaline elements on the surface, which is represented by cation exchange capacity. Altogether with the high pH values (7.00 – 10.00), biochars are quite effective sorbents and can adsorb metals/metalloids from the solution (ground water), especially in acidic soils (in the environments affected by intensive mining activities). Sorption\neffectiveness can be increased (especially for As (V) or Cr (VI) sorption) by modification of biochar by various types of secondary oxides. Innovative sorbent AMOchar (AMO + biochar) has been synthesized currently. The product was prepared by adding of biochar to the reaction solution during amorphous manganese oxide (AMO) synthesis. The AMOchar was formed mainly by Mn-oxalates which had coated surface of the pristine biochar. AMOchar composite was able to remove significantly higher amounts of various metal(loid)s from the solution despite the rather high pH of the material. Sorption effectiveness was high not only in case of Pb (II) sorption (almost 99%), and Cd(II) (51.2%), but also a very high amount of As(V), 91.4%. Additionally, both AMOchar composite was able to reduce Mn leaching. This can avoid potential post-contamination caused by the dissolution of less stable Mn-oxalates as observed in the pure AMO.
Fulltext: content.csg - PDF Plný tet: SKMBT_22316111113040 - PDF
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Effect of snowpack on runoff generation during rain on snow event.
Juras, Roman ; Máca, Petr (advisor) ; Ladislav , Ladislav (referee)
During a winter season, when snow covers the watershed, the frequency of rain-on-snow (ROS) events is still raising. ROS can cause severe natural hazards like floods or wet avalanches. Prediction of ROS effects is linked to better understanding of snowpack runoff dynamics and its composition. Deploying rainfall simulation together with hydrological tracers was tested as a convenient tool for this purpose. Overall 18 sprinkling experiments were conducted on snow featuring different initial conditions in mountainous regions over middle and western Europe.
Dye tracer brilliant blue (FCF) was used for flow regime determination, because it enables to visualise preferential paths and layers interface. Snowpack runoff composition was assessed by hydrograph separation method, which provided appropriate results with acceptable uncertainty. It was not possible to use concurrently these two techniques because of technical reasons, however it would extend our gained knowledge. Snowmelt water amount in the snowpack runoff was estimated by energy balance (EB) equation, which is very efficient but quality inputs demanding. This was also the reason, why EB was deployed within only single experiment.
Timing of snowpack runoff onset decrease mainly with the rain intensity. Initial snowpack properties like bulk density or wetness are less important for time of runoff generation compared to the rain intensity. On the other het when same rain intensity was applied, non-ripe snowpack featuring less bulk density created runoff faster than the ripe snowpack featuring higher bulk density. Snowpack runoff magnitude mainly depends on the snowpack initial saturation. Ripe snowpack with higher saturation enabled to generate higher cumulative runoff where contributed by max 50 %. In contrary, rainwater travelled through the non-ripe snowpack relatively fast and contributed runoff by approx. 80 %.
Runoff prediction was tested by deploying Richards equation included in SNOWPACK model. The model was modified using a dual-domain approach to better simulate snowpack runoff under preferential flow conditions. Presented approach demonstrated an improvement in all simulated aspects compared to the more traditional method when only matrix flow is considered.
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Arctic tundra dendrochronology
Lehejček, Jiří ; Svoboda, Miroslav (advisor) ; Monika, Monika (referee)
Historically unprecedented environmental change in the Arctic ecosystems is often given into the context of its past and possible future development. In the region where instrumental meteorological observations are scarce archives need to be investigated in order to address this issues. The comprehensive synthesis one of the archives: long-live circumpolar evergreen Juniperus communis L. shrub is presented here. 20 individuals from southwest Greenland were investigated at the cell anatomy level to understand the ecology of the species and unhide its potential for environmental and climate reconstructions. The findings are as follows:
i) Stop of exponential cross-sectional conduit-lumen widening with increasing age is in contrast with conduit-lumen nature of trees. This indicates that shrubs do not need to saturate their water and nutrient demands via traits of classical hydraulic conductivity law but rather developed different mechanisms. Extreme weather conditions result in prostrate growth form. However, different weather factors probably influence shrub growth differently: While snow and wind act mechanically (a), temperature influences the form of growth physiologically (b). a) So long as the young shrub stem has high resilience to bend back to an upright position after snow melt and so long as it can withstand the wind during the vegetation season it most likely grows upright and the conduit-lumens widen. b) Temperature, resp. freeze-thaw events are responsible for the shrubs preference of safety (finite size of conduit-lumens) over hydraulic efficiency, thus not allowing for more primary growth. All of these (and other) factors are apparently working together and the transition of vertical to more horizontal growth is gradual. As a consequence, the conduit-lumen sizes may not have to be further increased (due to ecophysiological restrictions possibly also must not) because water is no longer transported against gravity.
ii) Observed age/growth trend has to be taken into consideration for further employment of the wood anatomical parameter in paleoenvironmental studies. That is, shrub cell parameters can only be used for this purposes if correctly detrended. This allows for more accurate as well as longer reconstructions because youth trend was often neglected in reconstructions based on shrub annual-rings.
iii) The south-western Greenland Ice-Sheet (GrIS) melt rates reconstruction is presented for the whole 20th century. This part of GrIS is considered as the most active. According to the presented reconstruction current GrIS melt rates are not uncommon for the last century being comparable to first decades of 20th century. This finding is particularly important contribution to the debate on Atlantic meridional overturning circulation (AMOC). Too high fresh water inputs into the Northern Atlantic from GrIS melting may slow down or even stop the AMOC which would result in more continental climate in Europe. Presented results indicate that this threshold lies higher than observed current melt rates of GrIS.
Fascinating Juniperus comunnis species has shown to be able to address many ecological as well as environmental open questions and due to its longevity and abundant distribution has a great potential to become an important player in the Arctic research.
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