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Design of working part of the hydraulic circuit for hydraulic press
Pospíšil, Lukáš ; Šanca, Marek (referee) ; Škopán, Miroslav (advisor)
The master’s thesis is focused on the proposal of working part of the hydraulic circuit for the hydraulic press with a press force 400 kN. The thesis contains justifiable structural design of the linear hydraulic motor, which includes material choices, necessary calculations and simulations of material strength characteristics and the choice of the individual components. The thesis also includes a proposal of “heel valve” including the choice of individual components and basic function calculation of the hydraulic circuit of the hydraulic press.
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Spontaneous restoration of wetlands on arable land.
VITTEK, Petr
Spontaneous restoration of wetlands on arable land was observed in the part of South Bohemia. The main aim of the study was to describe colonization of the newly formed wetlands by plants in relation to character of the site and its surroundings (age and size of the wetland, distance to the field margin and to a nearest permanent wetland). Data were collected during three seasons (2011, 2012 and 2013) and analyzed using linear regression and ordination analyses (DCA, CCA). There were found no significant effects of the distance from the permanent wetland and the distance to the edge of the field on species composition of the newly created wetlands, only some trends were obvious. The effect of successional age of wetlands on their species composition was significant. In general, it was shown that spontaneous restoration of wetlands on arable land is possible.
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Differentiation within yeast populations of Saccharomyces cerevisiae: influence of cultivation conditions
Šimek, Jan ; Palková, Zdena (advisor) ; Dostál, Jiří (referee)
Long-time research of chronologically aging yeast populations of Saccharomyces cerevisiae laboratory strains revealed that yeasts are able to differentiate into specialized cell types. Differentiation of liquid cultures growing in glucose rich medium and differentiation of colonies growing on solid glycerol medium has been previously studied. These populations create two fractions of cells with diverse morphology which adapt their metabolism and physiology to enable a long-term survival of the yeast population in environment with limited nutritional potential. In this study, yeast subpopulations isolated from colonies growing on solid glucose medium and liquid cultures cultivated in glycerol medium were characterized. Newly isolated cell types were compared with already known cell types isolated from colonies and liquid cultures. Selected metabolic processes and stress resistance were analysed in studied populations. Based on previous studies of yeast differentiation, a spectrum of GFP-labelled marker proteins was choosen and production and localization of these marker proteins was monitored within yeast populations. Results of the analyses showed that type of medium and cultivation influence development and metabolism of each yeast cell type. Key words: Saccharomyces cerevisiae, BY4742, cell...
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The real use of operations research methods in conjunction with logistics technologies
Fesenko, Anastasiya ; Kuncová, Martina (advisor) ; Pelikán, Jan (referee)
This diploma focuses on the real use of operations research methods in conjunction with logistics technologies. The aim is to show the way of optimization and simulation methods application and to evaluate if these methods are suitable tools for logistics technology application. Following logistic technologies were analysed: Just in Time, Kanban, Cross-Docking and Hub and Spoke. Used mathematical tools include: mixed linear programming models, distribution models, methods of multi-criteria evaluation and simulation models. On the basis of mathematical models 4 examples of new technologies introduction or analysis of already functioning systems have been solved.
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Thermo-mechanical interaction in nonlinear vibrating systems
Pešek, Luděk ; Půst, Ladislav
The interaction between mechanical properties of vibrating system including hardening spring nonlinearity and thermal processes taking place in the rubber-like spring element having high inner damping are studied on one degree of freedom system. Basic differential equations for motion of mechanical system and for heat transfer are solved by numerical simulation.
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Thermally stratified atmospheric flow modelling
Jirk, Aleš ; Brechler, Josef (advisor) ; Jaňour, Zbyněk (referee)
In this thesis there is simulated an incompressible laminar flow in a higher-order accuracy around a circle cylinder with usage of an immersed boundary method and around a cylinder with a square cross-section with an influence of a thermal stratification. In the theoretical part the system of Navier-Stokes equations with Bussinesq approximation is derived and the methods for simulating are described. Fifth order WENO shock-capturing scheme reconstructs advections terms on the boundaries of control volumes. An explicit fourth-order Runge-Kutta scheme solves the first step of a fractional steps method. The obstacle with the circle cross-section is described by the immersed boundary method. In the implementation section there is interpreted the structure of programs for 2D cases. In the section Numerical experiments there is realized testing of the examples with the exactknown results the linear hyperbolic equations, the Burgers equations and the Euler equations and of a square cavity flow with Reynolds numbers of 100,1000 and 5000 with known numerical results for the Navier-Stokes equation. There is solved the flow around a square (and a circle) cylinder for Reynolds numbers 30; 200. Strouhal numbers are computed for von Kármán vortex street. Finally the flow around a square cylinder with influence of thermal...
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Interaction of line objects in ductile materials
Křišťan, Josef
Two dislocations of opposite signs interacting via their elastic fields are consider. They move in parallel slip planes in a PSB channel. Initially they are kept apart in straight screw positions. The walls of the channel are simulated as the elastic eld of rigid edge dipoles. The dislocations are modeled as plane curves. A special computer program based on the owing volume method and the method of lines is employed. Assuming an over-damped motion, we consider a linear relationship between the force acting on the dislocation and the velocity magnitude. The computation simulates the shape changes of the dislocations during their passing. The passing stress for various distances between the slip planes and for various channel width is compared with the bowing stress. The stress and strain controlled regimes of the dislocation motion are analyzed.
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