National Repository of Grey Literature 24 records found  beginprevious13 - 22next  jump to record: Search took 0.01 seconds. 
Mathematical and computational modeling of shape-memory alloys
Benešová, Barbora ; Roubíček, Tomáš (advisor) ; Krejčí, Pavel (referee) ; Stefanelli, Ulisse (referee)
This dissertation thesis is concerned with developing a mesoscopic model for sin- gle crystalline shape-memory alloys including thermo-dynamically consistent thermo- mechanical coupling - here the term "mesoscopic" refers to the ability of the model to capture fine spatial oscillations of the deformation gradient by means of gradient Young measures. Existence of solutions to the devised model is proved in a "phase-field-like approach" by a scale transition from a microscopic model that features a term related to the interfacial energy; this scale transition from a physically relevant model justifies the mesoscopic relaxation. Further, existence of solutions is also proved by backward- Euler time discretization which forms a conceptual numerical algorithm. Based on this conceptual algorithm a computer implementation of the model has been developed and further optimized in the rate-independent isothermal setting; some calculations using this implementation are also presented. Finally, refinements s of the analysis in the convex case as well as a limit of the phase-field-like approach in this case are exposed, too.
Czechoslovakia during the Second World War: Influence of the Second World War on the political development of Czechoslovakia
Krejčí, Pavel ; Pithart, Petr (advisor) ; Kysela, Jan (referee)
Czechoslovakia during the Second World War - Influence of the Second World War on the political development of Czechoslovakia The years 1938-1945 determined the development that culminated in the communist coup d'état in February of 1948. At the same time, Czech society was undergoing a deep crisis that has been caused by bitter disappointment of the end of the First Republic and its internal political problems. The Great Depression, mass unemployment and the inability of government officials to deal with this situation satisfactorily led to dissatisfaction with the economic arrangement of the First Republic and became the subject of radical change. According to many, the First Republic political party system also had failed. Too many political parties, the need for coalition governments, selfish adherence to party interests instead of national interests, intrigues, were all given as reasons why democracy had not been able to confirm its primacy in the moments when it was most needed. Betrayal by the Western Allies, especially France (under the strong influence of Great Britain) and the relatively friendly behavior of the Soviet Union during the Munich crisis undermined foreign policy concepts, held in the interwar period. All these events had meant that almost no one wanted to return to pre-war...
Utilization of liquefied soils in the form of backfilling self-compacting grouts
Chlachula, Jakub ; Krejčí, Pavel (referee) ; Drochytka, Rostislav (advisor)
The bachelor thesis focuses on the research of liquefied soils based on backfilling self compacting grouts. These grouts could be used as bedding for utility lines with lower cost and without unnecessary waste. The prerequisite is that the soil will be stabilized by a suitable stabilizing admixture, which should increase the strength of the composite. It will be necessary to liquefy this composite by using water and suitable liquefaction or plasticizers. As part of this thesis, currently known and used stabilizing admixture and plasticizers are also evaluated, same as the geological situation in the Czech Republic.
Non-conventional Applications in Thick Film Technology
Krejčí, Pavel ; Řezníček, Michal (referee) ; Szendiuch, Ivan (advisor)
This work deals with issues of application of the thick film technology in the non-conventional field. It includes the essential core of this technology, the overview of producers focusing on manufacturing thick film pastes and concrete examples of application. The general aim is to present growing opportunity of non-conventional application of thick film to the reader and to stimulate the imagination towards inventing new applications. In the experimental part of this work a design of a planar inductor on organic and anorganic substrate is carried out using thick film technology, screen and paste for high resolution.
Numerical modeling of magnetostrictive materials
Kholmetska, I. ; Chleboun, J. ; Krejčí, Pavel
An operator-differential model for magnetostrictive energy harvesting proposed in the literature is used to calculate the amount of harvested energy under some uncertainty in the Preisach density function. The uncertainty is modeled through a fuzzy set approach. In galfenol, an alloy of gallium and iron, however, the hysteresis phenomenon is present only weakly. This allows to propose a simpler, but computationally faster model without hysteresis. The new, simpler model has been identified from the measured magnetic and magnetostrictive cycles. The amount of harvested energy is of the same order in both models. Again, an uncertainty in the identified model can be considered and its impact on the amount of the harvested energy calculated.
Investigation of Miniature Devices for Collection of Hydride Forming Elements in Atomic Spectrometry Methods
Krejčí, Pavel ; Čelechovská, Olga (referee) ; Janoš, Pavel (referee) ; Otruba, Vítězslav (referee) ; Dočekal, Bohumil (advisor)
Capability of a prototype of miniature collection device based on a strip of the molybdenum foil for collecting hydride forming elements (As, Se, Sb and Bi) was studied. The device was combined with a miniature hydrogen diffusion flame for detection by atomic absorption spectrometry. The conditions for trapping and subsequent vaporization of analytes of interest were optimized. A twin-channel hydride generation system was used for study of mutual interference effects of co-generated hydride forming elements. The influence of modification of the molybdenum surface with noble metals - Rh, Pt and Ir on trapping and vaporization processes was also studied and changes of microstructure of the foil surface after modification were investigated using scanning electron microscope equipped with energy dispersive x-ray analyzer and electron backscattered diffraction system. Complementary radiotracer and radiography experiments were performed in order to determine trapping efficiency and to assess the spatial distribution of collected analytes within the device. Practical application of the method was demonstrated on determination of antimony in water samples at trace level. Possibility of multi-element analysis was demonstrated by combining the collection device with atomization and excitation of the analyte in microwave induced plasma and with detection by atomic emission spectrometry method. The results of the experiments proved that tested miniature collection device is capable of trapping analytes that form volatile hydrides. This device can be coupled to various types of atomizers, typically used in spectrometry methods. Thus, very sensitive and specific detection of hydride forming elements can be performed.
Current trends in the development of automatic tool change at milling machines
Krejčí, Pavel ; Matějka, Petr (referee) ; Pavlík, Jan (advisor)
The aim of this bachelor’s thesis is to do the research expertise mapping and sorting currently used equipment for the automatic tool change at milling machines, description and evaluation of this equipment.

National Repository of Grey Literature : 24 records found   beginprevious13 - 22next  jump to record:
See also: similar author names
1 KREJČÍ, Pavla
6 KREJČÍ, Petra
2 Krejčí, Patrik
20 Krejčí, Petr
6 Krejčí, Petra
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