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Helium Cryostat for Experimental Study of Natural Turbulent Convection
Urban, Pavel ; Jícha, Miroslav (referee) ; Rotter, Miloš (referee) ; Fedor,, Ján (referee) ; Musilová, Věra (advisor)
V disertační práci je popsán heliový kryostat s experimentální válcovou konvekční celou pro studium proudění při přirozené konvekci za velmi vysokých Rayleigho čísel Ra (až do řádu 10^15) a Nusseltových čísel Nu (až do řádu 10^4). Pracovní látkou je studené 4He, které umožňuje díky výhodným fyzikálním vlastnostem dosažení velmi vysokých hodnot čísel Ra. Návrh kryostatu je založen na koncepci lázňových NMR kryostatů s nízkým odparem kryokapalin. Ve středu kryostatu je umístěna konvekční cela o průměru 300 mm a výšce 300 mm. Celu tvoří horní a spodní dno a výměnná střední část. Tyto díly jsou spojeny rozebíratelnými přírubami těsněnými indiovým drátem. Výměnná část umožňuje snadnou modifikaci geometrie cely. Hlavní přednost kryostatu spočívá v minimálním vlivu konstrukce cely a použitých materiálů na studovanou konvekci. Cela kryostatu je navržena pro pracovní tlaky do 250 kPa.
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Design and verification of low temperature part of UHV – STM microscope
Voňka, Jakub ; Rotter, Miloš (referee) ; Urban, Pavel (advisor)
The diploma thesis addresses the design and experimental verification of cooling system and low temperature part of UHV - STM working in temperature range of 20K - 300K. Due to the demand of variable temperature, the flow cooling system with cryogenic (~5 K) helium (He) is used. Two variants of the low temperature part of the microscope are studied. First the version with cooling only the sample holder, and second with cooling of the whole STM. Designed cooling system consists of He flow cryostat allowing to connect it to the Dewar vessel with liquid helium (LHe) using a low-loss transfer line. The cryostat consists of He inlet and outlet, heat exchangers and copper strains (i.e. braids) for the thermal connection of the sample holder/STM and radiation shield around the STM with the heat exchangers. The thesis describes the design of the flow cryostat and its initial tests in the designed vacuum chamber. Heat flow through a spot contact is also discussed to estimate thermal conductance of insulation supports based on thermal resistance of spherical contacts. The thesis was elaborated in collaboration with the Institute of Scientific Instruments of the ASCR, v.v.i.
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Mining physiological data for automated educational feedback
Bašátková, Kateřina ; Lustigová, Zdena (advisor) ; Rotter, Miloš (referee)
1 Title: Mining Physiological Data for Automated Educational Feedback Author: Bc. Kateřina Bašátková Department: Department of Physics Education Supervisor: doc. RNDr. Zdena Lustigová, CSc., Department of Physics Education Abstract: This thesis deals with mining physiological data for automated educational feedback. The first part summarizes former researches of physiological data and its assertation into human behaviour. Special attention is devoted especially to eye tracking and measuring heart rate during behavioral processes. The second part is dedicated to author's own research how blink rate and heart rate are influenced by the degree of cognitive load. The research was executed on six subjects. The obtained data confirm correlation of blink rate and heart rate with the difficulty of the task. Keywords: heart rate, heart rate variability, blink rate, cognitive load
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Physics of medical devices
Čečák, Michal ; Lustigová, Zdena (advisor) ; Rotter, Miloš (referee)
My bachelor thesis deals with medical devices. Specially operates with four instruments, that people are familiar with them. The text is designed for teachers at primary and secondary school. Thesis includes also three worksheets. At the end of each are also links to website that we could find some new information about issues studies.
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Non-metallic resistive low temperature thermometers
Duda, Daniel ; Rotter, Miloš (advisor) ; Janů, Zdeněk (referee)
temperature calibration has been carried out on series of resistors made of RuO2 of SMD type in the bath of normal and superfluid helium in temperatures at 1.4 - 4.2 K with reference thermometer of saturated vapor pressure. Measured temperature dependence of electrical resistance of resistors was analyzed using the exponential function and Chebychev's polynomials. It was established an optimum calibration for the use of resistors as thermometers.
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