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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Experimentální analýza dynamických parametrů kolejového roštu / L'analyse expérimentale des paramtres dynamiques du rail grille

Podolník, Adam January 2014 (has links)
In terms of deciding on the appropriate use of the railway superstructure assemblies in both the recommendations arising from the theoretical analysis (modeling), as well as recommendations obtained under static and dynamic testing of the finished product play an important role. Such tests can then be applied in the laboratory or in the field. The thesis will be devoted to operational testing of selected track grid structures in situ. For measurement purposes an appropriate measuring point will be chosen and the methodology of measurement will be proposed. In terms of track geometry sections in curves will be selected. On the basis of tests carried out dynamic parameters of structures will be determined. To their evaluation suitable mathematical system will be chosen. It assumes the use of mathematical methods in time and frequency areas. In the thesis there will also be a comparison of the parameters of the tested structures. Based on the measurements it will be a source of recommendations for the practice.
72

Analýza vyvrtávacího procesu automatické horizontální vyvrtávačky / The analysis of boring process of automatic horizontal boring machine

Šohajek, Jiří January 2008 (has links)
The object of this dissertation is to analyse a drilling process of an automatic horizontal boring machine the SVD2 for drilling of bearing holes. There were problems with vibrations during drilling process, causing an extreme noise and this dissertation solves them. First of all it was necessary to analyse the vibrations, to examine a machining process and measure machine dynamics and statics. Another task was to compare measured results with mathematical models and after their analysis to design structural and other solutions. The SVD2 machine was designed on the basis of a previous type the SVD. Its conversion to a new one was based on adding of six spindles. As a result a number of drilled bodies was increased from one to four, so a performance was increased four times. That is why there was an original intention to rebuilt the other two spindle machines. To leave the basical parts of the machine without any modification ( such as a reinforcement of a mount and adjusting of a bigger distance of a side linear spindle guideway and a cross linear guideway of a support for clamping devices), would be unsuitable solution, which was confirmed after a measurement and a following analysis.
73

Využití piezo-materiálu pro získávání elektrické energie z vibrací / Using of Piezo-material for Energy Harvesting from Vibration

Hanus, Jiří January 2009 (has links)
Master’s Thesis deals with obtaining electricity from the vibrations of the surrounding environment through piezoelectric vibration generator. To simulation piezoceramics and design mechanical parts of the generator was used simulation program ANSYS 10.0. First, parameters of the designed piezoelectric generator were numerically calculated, and then these values were compared with the real sample. Further work is in the description of material properties of piezo materials.
74

Oscilační generátor s mechanickým resonančním členem / Oscillatory Power Generator Base on Mechanical Resonant Element

Mihalík, Vlastimil January 2009 (has links)
This work deals with the power supply of wireless sensors. When using a wireless sensor is desirable application of alternative energy sources, because the primary cells or batteries may reduce the extent or length of service of the sensor itself. Ambient energy can be used as a suitable alternative source. This energy must be in an appropriate form, which allows its conversion to electric energy. These appropriate, already used types include: solar en., temperature gradient en., en. of flowing liquids, vibration, etc. The advantage of vibrations is its presence in almost all mechanical systems. One of the possibilities for using the vibration of machine systems for power supply wireless sensors is using the vibration power generator with oscillating component. The generator must be designed so that its resonance frequency coincides with the frequency of vibration in the machine system. This method can be used only if the machinery system vibrations at least partially constant. Another option is to use the vibrations caused by, for example, transit transport, or different step acting factor. In this case, it is desirable that the generator is designed with variable resonant frequency, which can partly be achieved, for example, integrating several oscillating component in the body of generator. After the general analysis of the problem, graduation theses will be concerned with the possibility of use of energy from the short damped oscillation and step impulse. Focusing on a proposal of multi-element structures.
75

Vibrace valivých ložisek / Vibration of rolling bearing

Otoupalík, Jan January 2013 (has links)
The thesis deals with vibrations caused by geometric defect and fatigue damage of rolling element bearing. Hardware for vibration measurement is tested on 25 new pieces of NJ 304. Second part of the thesis examines if measuring of bearing vibration can help to detect a geometric defect. Geometric defects are detected according to a spectrum of vibration but the results are not absolutely exact. The possibility to detect geometric defects by measuring vibration has not been proven. The end of project tests diagnostic methods for rolling element bearings. The bearing defect was simulated to demonstrate bearing failure frequencies, envelope method and vibration spectrum.
76

Modelování a verifikace piezoelektrického generátoru / Modelling and Verification of Piezoelectric Generator

Lán, Radek January 2015 (has links)
This master's thesis deals with the development and verification of the model of the piezoelectric generator, incl. determination of its parameters. This mathematical model should be used as a tool for development of new devices, especially for analysis of applicability of available energy source (vibration) and for design of device itself. At first the review of energy harvesting is described deeply. Subsequently piezoelectric generators and the ways how we can model them, are depicted in details. The methodology of parameters estimation and model development is presented in state space or in MATLAB/Simulink environment and applied on the commercial generator Midé V21BL. A device has been made within the scope of the thesis, which can be used as an universal tool in experiments with generator. Finally the model is applied on the analysis of energy yield from man's walk and there is also brief introduction to model modifications.
77

Měření a analýza dynamických vlastností rotujících částí strojů / Measurement and analysis of dynamic properties of rotating machine parts

Gofroň, Vojtěch January 2015 (has links)
Diploma thesis focuses on measurement and analysis of shaft motion, torque, angular velocity and vibration. First part of the thesis deals with general issue of acquiring a digital signal. Next part describes suitable sensors for each measurement type, and data acquisition hardware. The last theoretical part describes methods for measurement data analysis and vibration diagnostics. Practical part of the thesis describes shaft motion and torque measurements made on laboratory equipment, and vibration measurement made on real machine system. Each measurement includes measurement data analysis and evaluation.
78

Diagnostika poruch elektrických strojů pomocí vibrací / Fault Diagnosis of electrical machines using vibrations

Čech, Roman January 2016 (has links)
The task of this thesis is to introduce the problems of vibrafon sources in asynchronous motor and their effects and risks to the engine. We will classify the sources of vibration, we will focus for the defects of bearings and for dynamic and static eccentricity. The thesis includes vibration measurement for asynchronous motor, analysis and evaluation of bearings defects and eccentricities.
79

Vnitřní akustika traktoru / Tractor Internal Acoustics

Hora, Otakar January 2016 (has links)
The diploma thesis focuses on the analysis of the internal acoustics of a tractor using the finite element method. The thesis also contains the analysis of excitation effects from individual sources of vibrations and evaluating the response in the internal acoustic chamber with special focus on the driver’s head. The conclusion should suggest appropriate structural modifications to reduce interior noise.
80

Metody analýzy vibračních signálů / Methods of analysis of vibration signals

Russ, David January 2016 (has links)
The main target of this master’s thesis is to focus on methods of analysis of vibration signals in electric machines. To get know the basic principles of the diagnostics methods, is important to clarify origin of the vibration signals and the impact they have. The selected methods were tested practically by measurement on electric machines. Measured data were processed in program LabVIEW. In this thesis were created programs which actually can be aplicated for complete vibrodiagnostics of electric machines in particular induction motors. The basic evaluation of vibration are the RMS value, Crest factor, time course and power spectrum. Results of this thesis are used to demonstrate how quickly and effectively can be vibration signals from electric machines evaluated.

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