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SMV-2015-23: Development of a low temperature system for a spectroscopy
Urban, Pavel ; Hanzelka, Pavel
The system for measurement of temperature of solid and liquid samples for spectroscopic measurement in the range of 77 K - 300 K was designed. For the above mentioned system, the pump vacuum line was designed and analysed for pumping of vacuum spaces of two types of liquid nitrogen cryostats used for spectroscopic measurements. The part of the solution is design of temperature sensor positions and an electrical resistance heater for the sample temperature stabilisation. Furthermore, an electrical resistance heater for heating/outgassing of the vacuum pump line was designed.
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Design of Balanced Scorecard information system
Urban, Pavel ; Mildeová, Stanislava (advisor) ; Tupý, Martin (referee)
This thesis is about Balanced Scorecard methodology and about information systems that support Balanced Scorecard in business. The main goals for the thesis are creating a design of Balanced Scorecard for an existing company and then design a BSC information system for this company. Business strategy management is introduced in the beginning of the theoretical part of this thesis. The description of each perspective of Balanced Scorecard follows. There is also a focus on BSC and strategy modifications over the time and one chapter is devoted to metrics, different types of metrics and relationships between them. Application part introduces the company used in the thesis. Based on the knowledge from the theoretical part the Balanced Scorecard is designed for this specific company and then an information system design is created.
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Design and Testing of Low Temperature Part of an UHV – SPM Microscope
Frolec, Jiří ; Vonka, J. ; Hanzelka, Pavel ; Králík, Tomáš ; Musilová, Věra ; Urban, Pavel
We have developed low temperature part of an ultra high vacuum scanning probe microscope (UHV-SPM) working at variable temperature within the range from 20 K to 700 K. To achieve the required temperature range, a flow cooling system using cryogenic helium (approximately 5 K) as a coolant was designed. The system consists of a flow cryostat and a flexible low-loss transfer line connecting a Dewar vessel with the flow cryostat. We have also tested liquid nitrogen (approximately 77 K) as an alternative low-cost coolant. Using nitrogen, the microscope can operate at temperatures of about 100 K and higher. As the flow of the coolant through the cryostat can cause thermally induced two-phase flow fluctuations resulting in instability in temperatures, preliminary tests were done in order to find ways of avoiding the temperature oscillations and optimising the cooling process.
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Temperature Inversion and Heat Transport Against the Temperature Drop in Two-Phase Convection of Cryogenic Helium
Urban, Pavel ; Schmoranzer, D. ; Hanzelka, Pavel ; Skrbek, L.
In the system of two bodies A and B connected by a two-phase vapour-liquid system consisting only of cryogenic helium, we observed anomalous heat transport from the colder but heated body B to the warmer but cooled body A. We noticed this effect during the process of liquid evaporation inside a cylindrical pressure convection cell used for study of Rayleigh-Bénard convection. This anomalous heat transfer occurs under non-equilibrium conditions, owing to the phase transitions that take place inside the cell while temperature inversion develops between the heated but cooler bottom plate and the cooled but warmer top plate. This process is, by virtue of the system being open with respect to heat transport, in no contradiction to the second law of thermodynamics, and a numerical model was formulated that describes the observations with good agreement.
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Cryogenic He experiment on Natural Turbulent Convection
Králík, Tomáš ; Urban, Pavel ; Musilová, Věra ; Hanzelka, Pavel ; Srnka, Aleš ; Repisky, Andrej
Cryogenic helium gas is a suitable fluid for study of natural turbulent convection at very high Rayleigh numbers. We present experimental method and new result on Reynolds and Péclet numbers characterizing large scale circulation (LSC) of fluid at Rayleigh numbers within the range from 1011 to 1015. Observation of LSC is based on measurement of local temperature fluctuations of convecting helium. For experiments we used a specially designed cylindrical cell of height L = 0.3 m and diameter D = 0.3 m with minimized parasitic effects on studied convection, previously published on CryoPrague 2006 [1].
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