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Stress-deformation analysis of the high voltage transmission tower
Kuběna, Tomáš ; Pokorný, Jan (referee) ; Fuis, Vladimír (advisor)
The thesis deals with the analysis of a high voltage power pole near the village Lešná, whose collapse will cause an outage of the electricity network in the area. The model of the pole was created on the basis of drawings provided by Arpex Moravia s.r.o. The pole is designed as a truss system using the general node method, subjected to the weight of the structure, wind and the weight of live conductors. The analytical calculation is performed in Matlab and then verified by numerical calculation in Ansys Workbench. When the pole is subjected to all previously mentioned loads, the maximum deformation has a magnitude of u_max=18.89 mm, which is mostly affected by the wind action. The resulting safety to elastic limit state is k_MSP=23.95. The pole is operated with sufficient safety and collapse will not occur under normal operating conditions.
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Life cycle assessment methods for BEV and PHEV batteries
Dvořák, Matouš ; Pokorný, Jan (referee) ; Fišer, Jan (advisor)
Electromobility is a current topic and a way to reduce the carbon footprint not only in personal transport. The operation of an electric car does not have a direct impact on emissions compared to an internal combustion engine car. However, the issue remains the production of the battery, which contains rare metals that are very energy and environmentally demanding to extract. The aim of this thesis is to analyse the energy consumption and emission footprint of the production of different types of batteries. The thesis includes a general introduction to the Life Cycle Assessment (LCA) method, followed by a chapter on battery design and the classification of batteries according to electrode chemistry. The analysis of LCA studies of batteries shows that the least energy intensive battery in terms of production is the battery with NMC cathode and in terms of emissions it is the battery with LMO cathode. However, the results are strongly influenced by the input data, which are often different in LCA studies, so it is not possible to draw a clear conclusion. Part of the thesis deals with the analysis of the environmental impacts of battery production using different energy mixes and different types of production technologies. The work can serve as a basis for a more detailed investigation of the production part of the battery and for minimizing the environmental impact of this process.
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Proposal of shaft alignment method for small rotors using digital image correlation
Hrůza, Vlastimil ; Pokorný, Jan (referee) ; Ščerba, Bořek (advisor)
The presented thesis deals with the design of a method for aligning small rotors, for which commonly available methods are not suitable. This is due to space restrictions around the coupling, which often do not allow installation of conventional alignment systems on the shafts. The proposed method therefore utilizes non-contact measurement of the surface of the shafts using digital image correlation (DIC). Calculation of misalignment and corrective moves is based on fitting the points measured on individual shafts with cylinders and evaluating the mutual position of their axes. To determine the area of applicability of the proposed method, sensitivity analysis was performed, which showed that the method gives good results for surface-accurate shafts with a uniformly applied speckle pattern for DIC measurement. Validation of the method was then carried out by measuring on a designed test rig using a commonly available laser alignment system. The validation measurement proved the functionality of the method and confirmed the conclusions of the sensitivity analysis.
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Comparison of approaches to the assessment of buckling of variously long and supported columns
Ostratická, Klára ; Pokorný, Jan (referee) ; Šebek, František (advisor)
The bachelor's thesis deals with assessment of the buckling stability. The differences between elastic and inelastic buckling and effects on the critical force are described. The effect of material, supports and length of the column is described in more detail. During buckling, the character of deformation changes, the compressed column starts to bend at a definite point. This point is called bifurcation point and the limit is amount of critical force. The calculation of critical buckling force is carried out analytically for selected examples using the Euler and Johnson methods. The results are numerically checked by the finite element method in Ansys. The results for linear buckling are identical. Examples of nonlinear buckling are also calculated numerically. The difference is found in critical force for contact surfaces without friction and with friction. Defining the critical force can prevent the collapse of the entire structure, thus avoiding catastrophic incidents.
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Comparison of operational vibrations of selected types of flexible couplings for high-speed applications
Práznovský, Alexander ; Pavlík, Ondřej (referee) ; Pokorný, Jan (advisor)
Focus of the bachelor thesis is the selection from suitable candidate of flexible couplings for high speed applications. Flexible couplings introduce excitation forces into the system that cause vibrations. It was necessary to determine which flexible coupling is the most suitable for the tested assembly. In the research section, the flexible couplings in particular were described, but also all the essential parts of the test assembly and their functionality. Furthermore, the data processing and evaluation procedure is described in the thesis. For the possibility of an overall processing of all measured data, a calculation using the finite element method was performed to determine the applicability of the double-loop flexible coupling. The output of the bachelor thesis was the selection of the best flexible couplings for the test assembly.
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A simplified model of the pad deformation of the journal bearing
Janiš, Tomáš ; Cabaj, Gabriel (referee) ; Pokorný, Jan (advisor)
The presented bachelor thesis deals with the calculation of deflection of a pad of a hydrodynamic radial bearing with tilting pads. This type of bearing is described by its characteristics, which are determined by means of simulations. Knowledge of these characteristics is important for predicting the behaviour of bearings in service and for the design of equipment using these bearings. The bearing characteristics are strongly dependent on the thickness of the lubricating film. This is in fact very thin and is therefore affected by the slightest deflection of the pad. This paper therefore deals with the calculation of pad deflection. With this calculation, the effect of pad deflection can then be included in downstream simulations to determine the bearing characteristics. The inclusion of this effect results in more accurate simulations. For this reason, a computational model of bearing pad deflection is developed. This model is based on the differential equation of the deflection line assuming small deformations. The temperature effects due to lubricant heating and the pressure effects due to bearing pad loading are included in this calculation. The deflection results from these loads are further compared with the results obtained by the finite element method. This comparison did not achieve the required compliance.
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Metabolic activity and possibilities of its prediction
Štrbík, Tomáš ; Pokorný, Jan (referee) ; Řehák Kopečková, Barbora (advisor)
Metabolic rate is a set of processes in the body that convert food into energy and building materials, allowing us to grow, move, and maintain health. Therefore, it is important, and in some cases of illness also necessary, to monitor this variable. Various methods have been developed to quantify metabolic rate. The most accurate results come from direct measurements, which are often unavailable or too expensive, and are therefore primarily used for medical and scientific purposes. As an alternative, estimation methods based on easily measurable variables offer a more practical approach in everyday practice. This work discusses the different methods of determining metabolic rate and the various factors that influence it. Finally, one of these estimation methods is applied to available data. After comparing the measured and estimated values, a MAPE value of up to 11% was achieved during the performed activity, while during rest, this value reached up to 154%.
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Sleep quality depending on room environment
Veličková, Kateřina ; Pokorný, Jan (referee) ; Fišer, Jan (advisor)
The aim of this diploma thesis was to determine the thermal resistance of selected sleep assemblies (clothing, mattress, blanket, pillow) using measurements with a thermal manikin and subsequently to determine the appropriate ambient temperatures at which a balanced thermal equilibrium between the sleeping person and their environment would be maintained. Four different assemblies were selected for measurement purposes, differing in the type of blanket used (summer blanket, quilt, cover, and no blanket). The influence of the thermal manikin's position on the measured value was also investigated. It was proven that the influence of position on the overall thermal resistance is negligible, with measured values ranging from 1.12 clo (assembly without a blanket in the side position) to 2.05 clo (assembly with a summer blanket in the back position). Subsequently, appropriate ambient temperatures were determined using the PMV model, which ranged from 24.4 °C to 28.6 °C. The two-node model proved to be insufficiently sensitive for the addressed issue, and the heat flux maps derived from the equivalent temperature model were not calibrated for sleep but for mild activity while seated. Nevertheless, they provided interesting information about the perception of thermal comfort in different parts of the body.
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A comparison of the functions of data acquisition programs for cDAQ
Zoubek, Vojtěch ; Krejčí, Petr (referee) ; Pokorný, Jan (advisor)
This bachelor's thesis deals with the measurement of physical phenomena using the CompactDAQ systems. The recherche part of the thesis shows the possibilities of the CompactDAQ and describes the communication of LabVIEW and MATLAB with the CompactDAQ hardware. The next section presents a LabVIEW VI application that measures the temperature, revolutions and vibration of a high-speed motor. In the last part is a comparison of LabVIEW and MATLAB environment.
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