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Stress-free and stress-assisted aging of NiTi shape memory alloys
Dlouhý, Antonín ; Bojda, Ondřej ; Fiala, J.
The present work investigates coherent Ni4Ti3 precipitates in a Ti-50,7at%Ni shape memory alloy after different thermo-mechanical treatments. The study is based on the quantitative TEM (transmission electron microscopy) image analysis using the ACC (Adaptive Contrast Control) programme. The attention is given to a number, size and volume fraction of individual crystallographic variants of the Ni4Ti3 precipitates. Preliminary results suggest that, after common heat treatments, the precipitation of Ni4Ti3 particles is inhomogeneous not only as far as the density of particles in the original B2 grains is concerned but also with respect to the distribution of the crystallographic particle variants. The possible influence of the heterogeneous Ni4Ti3 precipitation on the characteristics of the martensitic transformations B2-R-B19’ is discussed.
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Competence as a Factor Shaping Human Behavior Managers
Stuchelová, Jana ; Stejskalová, Irena (advisor) ; Tužová, Julie (referee)
My dissertation is focused on description of characteristics which are connected with competences. The main aim of my work has been to set up the manager competences. After the analysis among the students of Faculty of Management we found which competences were obtained during our studies and which ones we had already had when we came to faculty. In my theoretical part I described the manager as a personality including all his competences, their development and the methods of developing. Practical part deals with analysis among the students of Faculty of Management, evaluation and presentation of the results in the form of the charts and graphs.
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Studium difuzního proudu na hranici oblouku pomocí elektrických sond
Chumak, Oleksiy ; Hrabovský, Milan ; Kavka, Tetyana ; Kopecký, Vladimír
Electric probes were used for investigation of an intermediate layer between the arc and anode surface in regions outside the main current channel. Distributions of a diffuse current and the potential were measured. Resistance and heating of the intermediate layer by diffuse current were evaluated.It was found that not only the value of diffuse current strongly depends on distance from the arc but also the shape of the distribution and the position of the maximum of the current change with the distance. These trends can be explained by expanding of the plasma jet. Evaluated equivalent intermediate layer resistance shows widening of the conductive region in a stream wise direction. Variation of resistivity of the intermediate layer is much higher than variation of the potential drop on the layer. That means that distributed current as well as Joule heating of the layer are generally controlled by distributed resistance.
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Mg-alloy die-castings - trends in industrial
Svoboda, Rostislav ; Juřička, Ivo (referee) ; Čech, Jaroslav (advisor)
The aim of this thesis is to determine influence of porosity and shape-factor over mechanical properties, performed on cast samples from Aalen foundry (Germany), that were high pressure die casted from AZ91 D Alloy. Evaluation of these quantities was done using computer software Olympus Five. Measured values were subjected to statistical analysis in order to eliminate gross errors and determine linear dependence between mechanical properties and porosity eventually voids shape factor.
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Properties of thermo-visco-elastic material 42-809 for manufacturing of vibrodamping elements – 3.part
Svoboda, Jaroslav ; Pešek, Luděk ; Frölich, V. ; Klášterka, Petr
In the report the results of rubber elements properties made of thermo-visco-elastic material 42-809 at low temperatures are summariesed. The tests were performed by a loading fatigue machine INSTRON 8502 in a climate chamber. For improving an accuracy of measurement the test machine was equipped with a lesser force transduser Rumburk with a range up to 40kN. The report includes results of static and dynamic characteristics in temperature range 0 ÷ -50°C, measurement of residual deformations, relaxation time and evaluation of a cyclic loading influence to shapes of static characteristics of the rubber. Furthermore the results of rubber element life time and evaluation of friction behaviour at lower temperatures are presented. The limit lines for 10% of residual deformations are drawn here, too.
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Study of the properties of concrete with reinforcement, intended for the production of concrete egg-shaped tubes
Šťastný, Antonín ; Hela,, Vlastimil (referee) ; Hubáček, Adam (advisor)
This diploma thesis examines the properties of concrete with reinforcement, designed for the production of a concrete egg-shaped tubes . The stress is put on using various types of fiber reinforcements. Theoretical part is divided into 4 subsections. The topic of the first subsection is a concrete in general. Second subsection deals with various technology of production of concrete pipes. The third subsection is focused on description and summary of basic properties of concrete and reinforced concrete tubes. The last subsection deals with standardized procedures for testing concrete. Experimental part of this thesis is divided into two subsection. First subsection deals with design of a reference sample. Six different samples of a concrete were designed and their rheological properties were tested. Second subsection deals with the additi-on of various types of fiber reinforcement to the reference sample. Eight different admixtures of a concrete were added to the reference sample. Properties of these admixtures were tested in fresh and hardened state.
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