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Braking of an induction machine
Mareček, Šimon ; Janda, Marcel (referee) ; Mach, Martin (advisor)
The work is focused on the braking of an induction engine and the risks associated with it. In the first part, there are readers acquainted with the technical parameters of the induction engine, which is used for simulations. The second part focuses on the simulation program Ansys Maxwell and the finite element method. In the third part, there are readers introduced to a general description of the induction machine. The fourth part consists of countercurrent braking. The penultimate part is devoted to dynamic braking. The last part contains a brief introduction to generator braking. The chapters focused on braking are supplemented by simulated waveforms.
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Problems of the Expert Analysis of the Vehicle Movement and Braking Action in General Spatial Curve at Speed Higher than 50 km/h
Panáček, Vladimír ; Šachl, Jindřich (referee) ; Drahotský, Ivo (referee) ; Vémola, Aleš (advisor)
The present apparatus for the technical analysis of road accidents has no well-integrated information, recommendations or procedures of how to solve comprehensively the analysis of road accidents involving vehicles equipped with stabilization system of driving dynamics. The problem in the investigation of a vehicle movement in a curve is the ignorance of the contributions of vehicle dynamics intervention of the electronic stability system. Although some of the simulation software used in the analysis of road accidents makes it possible to take into account the modelled vehicle movement impacted by a stabilization system in the examined process, but the experts do not know what parameters should be entered in the numerical models of stabilization system in a computer programme. Therefore, the thesis investigates the issue of the expert analysis of vehicle riding and braking in a general spatial curve at speeds exceeding 50 kph with simultaneous examining the impact of electronic stability system chassis on vehicle driving dynamics. The thesis first deals with the solutions based on classical analytical methods, then dwells on experimental measurements in real conditions on testing grounds and, finally, addresses the use of computer simulation software in expert practice. Nevertheless, it is important to realize that no computer simulation software can be an absolutely unambiguous solver, and it is not enough to generate a computer simulation, but so obtained results should be evaluated and justified technically. Road accident analyst needs to know the impact of vehicle electronic stability control systems on vehicle movement. The thesis investigated the mutual relationship between the vehicle speed limit in a curve specified by analytical calculation and the vehicle speed in a curve experimentally detected by measuring the parameters of driving dynamics of a vehicle equipped with electronic stability system. The impact of selected electronic stability control systems of the chassis on the vehicle movement in the investigated processes in the curve was detected and quantified by driving experiments. Finally, the input values of significant quantities of computational models of the ESP simulation programs were found consistent with the results of experimental measurements in defined curves for the vehicles equipped with electronic stability systems. The results of the thesis can be used both in the expert and in the teaching activities.
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Identification of Relevant Tire Traces in Traffic Accident Place Based on their physical characteristics
Bilík, Martin ; Kovanda, Jan (referee) ; Kledus, Robert (referee) ; Bradáč, Albert (advisor)
The thesis deals with the possibilities of identifying the relevant tire traces at the place of a traffic accident based on their physical characteristics. Braking traces on the road are one of the most important objective elements for accident analysis, their easy and accurate detection is very important for accurate accident assessment. With the increasing technical equipment of vehicles, especially with the introduction of newer generations of braking assistance systems, traces left by the tires become almost invisible to the human eye. It is therefore highly desirable that their detection should be not only as accurate as possible but also as easy and fast as possible, not only for forensic experts, but especially for members of the traffic police departments. In line with the development and introduction of new safety and assistance systems for vehicles should also be the development of means and methods of providing the basis for technical analysis of traffic accidents. Reality shows that the procedures, even if still functional, are practically identical for several decades, are dependent on the subjective capabilities of the documenting person. An essential element of the work, compared to the previously described measurement procedures, is the use of modern methods and devices at the highest known level of knowledge. The aim is to find and verify a simple, accurate, subjectively least influenced detecting method for tire traces on the road. A series of measurements confirmed the possibility of using the thermal camera at the technical level usually available at the place of the accident, under limited atmospheric and time conditions. In addition, laser-induced plasma spectroscopy and rLIBS were used. This method of detecting spotless tire treads can be marked as a minimally feasible documentary and at the same time as fast enough, based on the measurements made and the intended removal of defects of the instrument in the development phase of the prototype.
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System analysis of braking truck - trailer combination
Haring, Andrej ; Kubjatko,, Tibor (referee) ; Řehák,, Miloslav (referee) ; Semela, Marek (advisor)
The dissertation deals with the issue of braking of articulated vehicles, especially articulated vehicles consisting of a tractor and a semi-trailer. This configuration was chosen with regard to the number of accidents and their consequences, and often also does not suit the technical condition of the tractor and semi-trailer, which is closely related to the safety of operation of these combinations. In the case of road accidents, the consequences are often very serious, whether it is personal injury or material damage. Investigating these accidents is a relatively demanding process, requiring a high degree of expertise as well as the necessary technical equipment. In contrast to these requirements, the availability of sources from which the necessary information can be drawn is relatively low. The available resources are mostly in a foreign language and are usually solutions to partial problems, not systemically comprehensive literature. Therefore, it is possible to say a "constant demand" for the available professional literature dealing with issues related to the solution of traffic accidents not only of combinations of vehicles, but of commercial vehicles as a whole. From the point of view of the importance, or topicality of needs arising from expert practice, the dissertation is thematically focused on braking of combinations of vehicles. There are several key reasons to focus on articulated vehicles. First of all, this is due to the specific character of the vehicle itself, which consists of two communication-linked brake systems. Other reasons are that the information contained in the dissertation, whether it is descriptive information, assessment of the technical condition of the systems, or the measurement results themselves, can be partially or even fully used for stand-alone towing vehicles or trailers. However, not all problems related to this issue can be solved within the dissertation. Therefore, in the dissertation, significant influences are selected, the solution of which, given the frequency and severity, the author considers essential. From the title of the dissertation it follows that this is a system analysis of the braking of combinations of vehicles. The system concept of solving a problem situation and selected problems are a guarantee that really essential parameters are selected within the content possibilities and scope of the dissertation and the system approach to their solution allows a "general" application in solving similar problems. The aim of the dissertation is a system analysis of the influence of selected parameters on the overall braking effect and stability of commercial vehicle combinations, analysis of input parameters on the decision logic of electronic brake system control unit, where procedures but also conclusions can be applied in similar cases with similar input parameters and decision criteria. Another partial goal is to develop a framework methodology for determining the technical condition of individual components of brake systems of commercial vehicles, which will be possible to apply especially in trucks, where electronically controlled systems are installed. Here, too, a systemic concept is applied, which will enable a wider use of this methodology.
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The use of hydraulic disc brakes for road bikes
Dvořáková, Barbora ; Lošák, Petr (referee) ; Šebek, František (advisor)
This bachelor's thesis is focused on the usage of hydraulic disc brakes on road bikes. The thesis is divided into two parts. In the first part, there is a research focused on differences in construction and properties of hydraulic disc brakes in comparison with rim brakes. The main emphasis is placed on evaluating all advantages and disad-vantages of the hydraulic disc brakes in comparison with rim brakes. Evaluation is conducted both from the functional point of view and user point of view with taking different requirements of both recreational level cyclist and professional cyclist into account. The aim of the second part is the numerical simulation of loading of the frame and fork for both types of brakes. The goal of this part is an overall assessment of suitability of hydraulic disc brakes for the road bikes.
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Quadbike (ATV) Driving Behaviour
Příplatová, Miroslava ; Krejsa, Ivan (referee) ; Semela, Marek (advisor)
This thesis deals with Quadbike (ATV) driving behaviour. This work describes the construction of ATVs, driving behavior and specifications ride them. In this work was performed measurements of braking, acceleration tests, measurements of transverse movement ATVs and subsequent analyse of obtained data. The measured values can be used for working forensic experts and analysts accidents.
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Friction Modification within Wheel-Rail Contact
Galas, Radovan ; Meierhofer, Alexander (referee) ; Pfaff, Raphael (referee) ; Hartl, Martin (advisor)
Předložená disertační práce se zabývá experimentálním studiem modifikátorů tření a maziv pro temeno kolejnice, které jsou aplikovány do kontaktu kola a kolejnice za účelem optimalizace adheze a redukce hluku. Hlavním cílem práce bylo objasnit vliv aplikovaného množství a složení těchto látek na adhezi v kontaktu. Hlavní pozornost byla věnována zejména potencionálním hrozbám souvisejících s kriticky nízkou adhezí, která může nastat po aplikaci těchto látek. Experimentální studium probíhalo v laboratorních i reálných podmínkách, konkrétně v tramvajovém provozu. V případě laboratorních experimentů byl využit komerční tribometr a dvoudiskové zařízení umožňující simulovat průjezd vozidla traťovým obloukem. Kromě samotné adheze bylo při experimentech sledováno také opotřebení a míra hluku. Výsledky ukázaly, že maziva pro temeno kolejnice jsou schopna poskytovat požadované třecí vlastnosti, nicméně jejich chování je silně závislé na aplikovaném množství. V případě předávkování kontaktu dochází ke kriticky nízkým hodnotám adheze, které vedou k výraznému prodloužení brzdné dráhy. V případě modifikátorů tření bylo ukázáno, že chování těchto látek je výrazně ovlivněno odpařováním základního média. Výsledky také ukázaly, že nadměrné množství částic pro modifikaci tření může způsobit kriticky nízké hodnoty adheze. U obou výše zmíněných typů produktů byl prokázán pozitivní vliv na míru opotřebení a míru poškození povrchu, zatímco významná redukce hluku byla dosažena pouze v případech, kdy došlo ke značnému poklesu adheze. V závěru této práce jsou uvedena doporučení pro další výzkumné aktivity v této oblasti.
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Aircraft Braking Systems
Bulko, Martin ; Koštial, Rostislav (referee) ; Bencalík, Karol (advisor)
The bachelor thesis focuses on problems of braking of aircraft. It describes constituent systems of braking and explains on schemes their function and application. It mentions main advantages and disadvantages of these systems with their subsequent comparison. The thesis includes a summary of braking systems which are used by commercial airplane with capacity over a hundred passengers. There is also analyzed development of braking force size of these airplanes.
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Measuring the Deceleration of Trucks up to 12 Tons of Weight with the Use of Engine Braking
Kašparová, Hana ; Sedlák, Jaroslav (referee) ; Bradáč, Albert (advisor)
This thesis deals with braking effect of the truck’s engine. The theoretical part introduces the reader to the basic construction of trucks, describes most using engine and defines the factors having a significant effect on engine braking. In the practical part the reader is familiar with the technique used in making the measurement and description of the vehicle chosen for the implementation of measurement. The result of the practical part is the values obtained by measurement including their interpretation contained in the conclusion.
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