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Modelling of Dynamic Properties of Gearboxes Using Virtual Prototypes
Otipka, Václav ; Trochta,, Miroslav (referee) ; Žlábek,, Pavel (referee) ; Píštěk, Václav (advisor)
Transmissions are very widespread across all categories of technical products. Their role is irreplaceable, however, their operation is always associated with the generation of significant vibration and noise, which is also considered one of the main disadvantages, which manifests itself especially in heavily loaded transmissions and represents a disadvantage mainly in terms of product competitiveness and possible legislation problems. This problem can be solved in part through sophisticated transmission optimization, which, however, requires considerable effort, time, and money. This is the main reason why there is constant pressure to find efficient solutions for optimization and why the scientific community is still paying considerable attention to this area. At present, a combination of computational and experimental approaches is used for overall optimization in this area. This dissertation is focused on the prediction and understanding of the transmission dynamic behaviour, which requires the construction of an advanced, complex computational model. Computational modelling is supported by a number of partial technical experiments, which are used to validate the results.
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Concepts of electric vehicles drivetrain
Bede, Filip ; Píštěk, Václav (referee) ; Kučera, Ondřej (advisor)
This bachelor thesis focuses on a review, analysis and comparison of current electric vehicle drive concepts that form the basis for modern electric vehicles. For a better understanding of the composition and application of the concepts, the individual elements of the powertrain have also been discussed in detail in the thesis. The thesis starts with a brief overview of important milestones in the field of electric mobility. It then continues with a detailed discussion of the electric motors, batteries and gearboxes used. These are followed by drive concepts analysed in terms of their impact on the drivability and efficiency of electric vehicles. Examples of modern electric vehicles are then given to demonstrate the concepts in practice. Finally, current internal combustion engine drive concepts are also presented and compared with EV concepts, thus providing a comprehensive view of current trends in automotive technology.
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Crank mechanism of a four-cylinder in-line gasoline aircraft engine
Doležal, Jakub ; Kučera, Pavel (referee) ; Píštěk, Václav (advisor)
This thesis is focused on design of a steel connecting rod for the aircraft engine Walter Mikron III C produced by Parma-technik s.r.o., which could be an alternative to the existing aluminium alloy connecting rod. Research of aircraft engines and connecting rods is done before the design work itself, together with explanation of the calculation of dynamic stresses in the crank mechanism. In practical part, design of the crank mechanism is analysed, followed by the calculation of its dynamic stresses, analytically and by 1D simulation in the GT-Suite Cranktrain software. Connecting rod strength analysis is performed by analytical calculation, which is verified by FEM analysis in Ansys Mechanical software, both approaches evaluating connecting rod tension and fatigue safety. Similarly, the steel connecting rod is designed and evaluated in two designs, with an I and H shank. Drawing documentation of both designs of the connecting rod is output of this thesis.
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Designing a virtual world for testing autonomous vehicles
Turek, Martin ; Píštěk, Václav (referee) ; Kučera, Pavel (advisor)
The bachelor's thesis deals with a design of a virtual world for testing autonomous vehicles, which is based on a real location in the Czech Republic. A vehicle controlled by a flawed autonomous driving algorithm or ADAS system potentially poses a major safety risk to all road users. Because of that everything needs to be tested very thoroughly, with a virtual simulation environment being a cost-effective alternative to the expensive testing of prototypes in the real world. A detailed virtual representation of the selected location was created in the RoadRunner software using digital maps and photographs. The functionality of the created world was verified in Unreal Engine through a simple simulation designed in the Simulink environment. The output of this work is a functional virtual environment, representing the immediate surroundings of the FME in Brno. The created world contains all important road infrastructure, and the visual authenticity of road surroundings is achieved by the placement of 3D models of real objects.
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Ammonia as an alternative fuel
Radil, Jan ; Kučera, Pavel (referee) ; Píštěk, Václav (advisor)
Replacing current fossil fuels as one of the main causes of the high levels of unwanted particles in the air with greener alternatives is growing in importance every year. In recent years, ammonia has become one of the most frequently investigated alternative fuels with the potential to reduce greenhouse gas emissions in the transport and energy sectors. This bachelor thesis examines the issue of this substance in the context of its use as a fuel. Thesis brings an overview of the current state of research and development of ammonia as an alternative fuel and highlights its potential and challenges in the transition to a low-carbon economy. The reader is introduced to the basic properties of ammonia, production, transport and storage technologies. Comparisons with other fuels, in particular hydrogen, as another alternative fuel are also included. An overview of the possible applications of ammonia as a fuel in current internal combustion engines and fuel cells is also given. This overview is supported by several studies and researches that are currently dealing with this issue. Besides this, the thesis also mentions the most discussed projects for the application of ammonia as a fuel in the automotive and marine industries. In conclusion, all the collected informations are summarized and specific conclusions are drawn in terms of possible future applications of ammonia as a fuel.
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Lane detection for autonomous vehicles
Holík, Štěpán ; Píštěk, Václav (referee) ; Kučera, Pavel (advisor)
This thesis focuses on the design and experimental verification of a system for lane detection, trajectory estimation and vehicle position. The goal was to develop a system composed of algorithms with its respective functions. Data collected with ZED 2 camera, the U-Net neural network model, and computer vision were used to reduce false positive predictions using a temporal window. Trigonometric calculations and camera parameters were used to estimate the vehicle’s position relative to the trajectory. One of the outcomes of this thesis is TuSimple dataset extension with the data captured with ZED 2 camera. Experimental verification demonstrated the system's functionality with high detection reliability in simple model situations, such as driving on a straight road segment. As the complexity of the model situations increased, the system's reliability decreases. Despite these shortcomings, the experiments showed that the system is able to detect lane boundaries and estimate an optimal vehicle trajectory. The algorithms for trajectory and vehicle position determination depend on the initial prediction of the lane boundaries, but they are functional and effective.
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Rotary Piston Engine for Small Mobile Systems
Drbal, Milan ; Puškár, Michal (referee) ; Žák,, Marek (referee) ; Píštěk, Václav (advisor)
The dissertation deals with the issue of 1D modelling of a rotary piston engine and prediction of engine characteristics for use in its further development. In this work, the 1D mathematical model of the engine is validated by measuring the combustion pressure in the work chamber, in the intake section and further in the exhaust channel. These data are used to determine the coefficients of the combustion model and, above all, the combustion chamber leakage model. Both effects cannot be modelled accurately included without measuring the work chamber pressures. The use of 1D mathematical simulations is well described in the literature for a reciprocating engine. However, their use for a rotary piston engine is more complicated from the point of view of the geometric differences of both types of engines. In this work, a suitable method of modelling rotary piston engines and their verification using technical experiments and CFD simulations will be described.
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Neural networks used in autonomous vehicles
Ryšavý, Jan ; Píštěk, Václav (referee) ; Kučera, Pavel (advisor)
This bachelor thesis deals with the use of neural networks in autonomous vehicles. The first part of the thesis presents the basic principles of neural networks and learning methods that are used in autonomous vehicles. Then the thesis describes the architecture and functions of neural networks. The second part of the thesis also describes the different types of autonomous vehicles, their classifications and an overview of the sensors used by autonomous vehicles. The last part of the thesis deals with the implementation of neural networks in ECUs using programming languages and libraries, and applications such as object detection and marker recognition.
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Operation of electric vehicles, hybrid vehicles and vehicles with an internal combustion engine
Herzog, Radim ; Píštěk, Václav (referee) ; Kučera, Ondřej (advisor)
This bachelor's thesis deals with the comparison of different propulsion concepts and their consumption, efficiency, and amount of emissions produced during operation. Although electric vehicles do not produce any local emissions, it is necessary to consider that emissions are generated during the production of electricity in power plants. The main part of the thesis introduces the functional principles of individual propulsion systems. Furthermore, it describes the formation of exhaust gas emissions in combustion engines and outlines their limits. Subsequently, the amount of emissions produced by a power plant for the operation of a specific example of an electric vehicle and a hybrid vehicle is calculated. Finally, a comparison of emissions production from representative examples of each propulsion system is illustrated.
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Analysis of the crank mechanism of a two-stroke engine
Matyáš, David ; Píštěk, Václav (referee) ; Svída, David (advisor)
This diploma thesis is a comparison of two versions of the crank mechanism of the Jawa 350 two-stroke engine. The diploma thesis if prefaced by researching the design solutions of multi-cylinder two-stroke engines with examples of their use. The following is a description of the theoretical properties of the two examined crank mechanisms in terms of inertial effects. For both engine concepts, the engine performance characteristics is measured and compared to each other. The engine with modified crankshaft is subjected to a pressure indication, which serves as one of the inputs to the strength analysis of the crankshaft. This is done by a combination of MBS simulation, FEM analysis and calculation of fatigue safety factor by LSA analytic method.
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