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Heat exchanger using structured material
Simon, Jakub ; Čížek, Petr (referee) ; Vaverka, Ondřej (advisor)
The aim of this work was to develop and describe a design method of a heat exchanger using Triply Periodic Minimal Surfaces (TPMS) structures and to validate it by design, fabrication, and experimental testing of a working sample. It is an oil-water cooler fabricated additively by Laser Powder Bed Fusion on an SLM 280 HL machine from AlSi10Mg material. After a series of analyses and tests, a cubic diamond structure with a minimum wall thickness of 0.7 mm and a range of relative densities of 15 to 25 % (cell edge length 11.1÷18.5 mm) was chosen for the developed method. The method also includes a prediction script of the performance of the proposed heat exchanger, which was created from data measured during testing of samples with different cells configurations. The method itself guides the user step-by-step from the selection of input requirements, through the estimation of performance, to the two-step parametric modelling of the TPMS exchanger itself (explicit and implicit). The functional sample created using this method achieved heat flows of 315,25 W, which is 4.2 % higher than the reference plate exchanger. The TPMS exchanger also has a 78 % smaller heat transfer body and 62 % less total mass. The differences between predicted and actual heat flows were up to 18%. In its current state, the method is suitable for the design of TPMS heat exchangers with heat flow of 50 to 230 W. However, it is generally versatile and can also be used to map other areas, thus making it more accurate.
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Summary of the Liquid-Gas Ejector Hydraulic Behavior - Theory and Practice
Gebouský, Ondřej ; Haidl, Jan
Liquid-gas ejectors (LGEs) are fascinating devices that use the kinetic energy of the liquid jet to entrain and eventually compress the gas. LGEs find applications in both industry and everyday life, e.g., as sprayers. However, a complex and reliable method for LGE design was not available in the open literature until recently. This contribution follows up on our recent works about the hydraulic behavior of LGE with undisturbed and destabilized liquid jets. This paper aims to summarize the device’s complicated hydraulics and characterize its optimal design for three industrially relevant applications - (a) LGE as the vacuum pump, (b) LGE as the gas purification equipment, and (c) LGE as the gas distributor for bioreactors.
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Design and analysis of split-phase induction motor
Nekovář, Martin ; Hájek, Vítězslav (referee) ; Vítek, Ondřej (advisor)
The bachelor‘s thesis deals with the construction, operation principle, design method and analysis of the magnetic circuit of single-phase induction motor with auxiliary phase. The auxiliary phase is considered as winding with series connected electrolytic capacitor. In the first charter is written a general view of single-phase motors. Furthermore, in the following section discussed the design of these machines. Principle of operation as the next section contains an explanation of torque using the theory of two magnetic fields acting against each other. The design method of single phase motor is described the procedure for calculating. Subsequently, two proposals of single-phase induction motor with auxiliary winding were developed according to the method of design and an analysis of their magnetic circuits using the finite element method was made.
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The methodology for calculation small induction motor
Bureš, Petr ; Duroň, Jiří (referee) ; Hájek, Vítězslav (advisor)
This thesis addresses analysis of problematics concerning induction motors. The introduction is dedicated to description of basic principles of induction motor functions, describes individual construction components and also focuses on brief description of current regular design of those machines. The following section is dedicated to the design method and procedure for calculating, mainly focused on single phase induction motor with connected capacitor. The last section is focused on problematics concerning induction motor efficiency together with possible methods of loss reduction and efficiency improvement following the example of engine design.
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Strengthening of axially loaded steel members under load
Vild, Martin ; Wald,, František (referee) ; Křivý,, Vít (referee) ; Bajer, Miroslav (advisor)
Dissertation focuses on strengthening of axially loaded steel members strengthened under load. Strengthening under load using welding is time and financially efficient. Plastic design can be used for members without stability problems. However, the design of members susceptible to buckling is difficult and opinions of researchers differ on this matter and there are only several experiments. The dissertation is focused on strengthening under load of members with selected cross-sections susceptible to flexural buckling. It is necessary to check the resistance of the base member weakened by the elevated temperatures caused by welding. The preload and welding – residual stress and deformations – must be taken into account for the determination of the buckling resistance of the member strengthened under load. The aim of this dissertation is to provide the load resistance of selected compressed members strengthened under load. Author performed experiments on members with the H and L shaped cross-sections and seamless tubes. Other experiments were performed on members with H shaped cross-section and rectangular hollow sections to determine the resistance of base member during welding. These served to validate numerical models which helped to increase the number of specimens for statistical evaluation. Analytical models to determine the load resistances of the base member during welding and the strengthened member were developed using experiments from literature and author’s experiments and numerical models. The simplified model is conservative and suitable for practical design. The complex model is suitable for scientific purpose and it provides both deformation and load resistance using modified imperfection factor. It provides a good agreement with the experiments. Doctoral thesis also includes practical recommendations for design and execution of strengthening under load using welding.
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Strengthening of axially loaded steel members under load
Vild, Martin ; Wald,, František (referee) ; Křivý,, Vít (referee) ; Bajer, Miroslav (advisor)
Dissertation focuses on strengthening of axially loaded steel members strengthened under load. Strengthening under load using welding is time and financially efficient. Plastic design can be used for members without stability problems. However, the design of members susceptible to buckling is difficult and opinions of researchers differ on this matter and there are only several experiments. The dissertation is focused on strengthening under load of members with selected cross-sections susceptible to flexural buckling. It is necessary to check the resistance of the base member weakened by the elevated temperatures caused by welding. The preload and welding – residual stress and deformations – must be taken into account for the determination of the buckling resistance of the member strengthened under load. The aim of this dissertation is to provide the load resistance of selected compressed members strengthened under load. Author performed experiments on members with the H and L shaped cross-sections and seamless tubes. Other experiments were performed on members with H shaped cross-section and rectangular hollow sections to determine the resistance of base member during welding. These served to validate numerical models which helped to increase the number of specimens for statistical evaluation. Analytical models to determine the load resistances of the base member during welding and the strengthened member were developed using experiments from literature and author’s experiments and numerical models. The simplified model is conservative and suitable for practical design. The complex model is suitable for scientific purpose and it provides both deformation and load resistance using modified imperfection factor. It provides a good agreement with the experiments. Doctoral thesis also includes practical recommendations for design and execution of strengthening under load using welding.
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The methodology for calculation small induction motor
Bureš, Petr ; Duroň, Jiří (referee) ; Hájek, Vítězslav (advisor)
This thesis addresses analysis of problematics concerning induction motors. The introduction is dedicated to description of basic principles of induction motor functions, describes individual construction components and also focuses on brief description of current regular design of those machines. The following section is dedicated to the design method and procedure for calculating, mainly focused on single phase induction motor with connected capacitor. The last section is focused on problematics concerning induction motor efficiency together with possible methods of loss reduction and efficiency improvement following the example of engine design.
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Design and analysis of split-phase induction motor
Nekovář, Martin ; Hájek, Vítězslav (referee) ; Vítek, Ondřej (advisor)
The bachelor‘s thesis deals with the construction, operation principle, design method and analysis of the magnetic circuit of single-phase induction motor with auxiliary phase. The auxiliary phase is considered as winding with series connected electrolytic capacitor. In the first charter is written a general view of single-phase motors. Furthermore, in the following section discussed the design of these machines. Principle of operation as the next section contains an explanation of torque using the theory of two magnetic fields acting against each other. The design method of single phase motor is described the procedure for calculating. Subsequently, two proposals of single-phase induction motor with auxiliary winding were developed according to the method of design and an analysis of their magnetic circuits using the finite element method was made.
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Workbook proposal for teaching Mathematics at primary and secondary school, chosen chapters - The basics of statistics
POVJAKALOVÁ, Marie
The main object of my final work is creating worksheets for teaching mathematics unit {\clqq}The basics of statistics{\crqq} using the interactive whiteboard and a computer and to find out how interactive teaching helps in the comprehensive educational process. The work is divided into three parts. In the first part I occupy myself with motivation theory and various stimulating teaching methods, especially with the design method. In the second part I analysed the current state of use computers and interactive whiteboards in teaching mathematics. The third practical part is consists of worksheets for the interactive whiteboard, that I created and the project. Then I occupy myself with application worksheets in teaching pupils in the second year of the secondary vocational school and I compare it with classic teaching. In conclusion I gave results and pieces of knowledge that I acquired during this teaching.
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