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Dynamika soustav těles s neurčitostním modelem vzájemné vazby
Svobodová, Miriam ; Lošák, Petr (referee) ; Hadaš, Zdeněk (advisor)
This diploma thesis deal with evaluation of the impact in the scale of uncertaintly stiffness on the tool deviation during grooving process. By the affect of the insufficient stiffness in each parts of the machine, there is presented a mechanical vibration during the cutting process which may cause a damage to the surface of the workpiece, to the tool or to the processing machine. The change of the stiffness is caused in the result of tool wear, impact of setted cutting conditions and many others. In the first part includes teoretical introduction to field of the uncertainty and choosing suitable methods for the solutions. Chosen methods are Monte Carlo and polynomial chaos expansion which are procced in the interface of MATLAB. Both of the methods are primery tested on the simple systems with the indefinited enters of the stiffness. These systems replace the parts of the stiffness characteristics of the each support parts. After that, the model is defined for the turning during the process of grooving with the 3 degrees of freedom. Then the analyses of the uncertainity and also sensibility analyses for uncertainity entering data of the stiffness are carried out again by both methods. At the end are both methods compared in the points of view by the time consuption and also by precission. Judging by gathered data it is clear that the change of the stiffness has significant impact on vibration in all degrees of freedome of the analysed model. As the example a maximum and a minimum calculated deviation of the workpiece stiffness was calculated via methode of Monte Carlo. The biggest impact on the finall vibration of the tool is found by stiffness of the ball screw. The solution was developed for the more stabile cutting process.
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Flow rate measurement for hydraulic turbine model tests
Neděla, Jiří ; Dokoupil, Pavel (referee) ; Machů, Tomáš (advisor)
This thesis deals with problematice of flow rate measurement for hydraulic turbine model tests. Theoretical part is devoted to literary search of flowmeters and comparison of their accuracy. The practical part deals with evaluation of measurement uncertainties during calibration of the flowmeter. It also includes verification of the measurement accuracy of the flowmeter indicated by the manufacturer.
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Confirmation of the Performance of Thermal Shock Test Chambers
Konupka, Richard ; Šedivá, Soňa (referee) ; Beneš, Petr (advisor)
The bachelor’s thesis deals with problematics of confirmation of temperature shock chamber and methodology for its successful implementation. Theoretical part deals with brief overview of environmental test chambers used for testing temperature and humidity changes on tested samples. Bachelor’s thesis also deals with analysis of methodology for confirmation of temperature chambers according to the technical standard which will be partially used for methodology proposal of temperature shock chamber. Practical part of the thesis is gradually devoted to the measurement procedure proposal, where is discussed chosen temperature sensors and fixture of sensors in the chamber. Also proposed procedure of confirmation is shown, described measurements, calculation procedures, uncertainty estimations and at the end of the thesis are discussed results.
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Contactless temperature measurement
Závodný, Ondřej ; Bejček, Ludvík (referee) ; Beneš, Petr (advisor)
In this bachelor thesis I outlined the problems of non-contact measurement and practical verification of the basic parameters thermo camera Fluke Ti20. It is especially on the experimental measurement of the source of the reference temperature and the product to demonstrate the impact of emissivity. The aim of this work is a practical verification thermo cameras parameters, the determination of uncertainties and to explore the effects of parasitic repeated measurements. The basic part is a brief recorded history, the general relations and principles of the non-contact measurement, as well as their own use and typical parameters. In the next chapter you more acquainted with itself thermo camera, properties and basic parameters. The practical part is about the measurement itself. The main objective then was to verify the accuracy of reported thermo camera and examining the impact of emissivity.
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Flow measurement
Schoř, Zdeněk ; Boček, Petr (referee) ; Beneš, Petr (advisor)
This bachelor thesis deals with flow measurement of liquids. The first part is a theoretical analysis with an overview of the most important parameters of flow sensors, the main parasitic influences and methods for calibration of flow sensors. The second part is the design and realization of the laboratory apparatus for measuring the flow of water, which is intended for the teaching of students. The apparatus is designed to test four flow sensors using weighing reference. The result of the practical part is the measurement of the basic characteristics of the flow sensors used and comparison of the obtained values with the data from a manufacturer. Further parasitic influences are added during the measurement and is determined to what extent they affect accuracy of the measurement.
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An Extended Model of a MEMS Gyroscope: Design and Identification
Vágner, Martin ; Sopata,, Milan (referee) ; Tůma, Jiří (referee) ; Beneš, Petr (advisor)
The thesis is aimed on measurement and modeling of MEMS gyroscopes based on input-output characteristics. The first part briefs the state of the art. The second part is dedicated to measurement methodology. Critical points and sources of uncertainty are discussed and evaluated using measurements or simulations. The last part shows key characteristics of MEMS gyroscopes based on the survey of a group of different sensor types. The results have revealed significant influence of supply voltage that causes bias drift of the gyroscope and bias drift of the internal temperature sensor. The error can be comparable to temperature drift; however, this effect is not addressed in the literature. The second observed effect is temperature dependency of angle random walk. In the last part, a general model of a MEMS gyroscope is rewritten to reflect observed effects. Moreover, the structure is selected to be easily extendable and the coefficients are expressed to allow a comparison of nominal parameters of different sensors.
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Processing of Uncertain Information in Databases
Morávek, Petr ; Dvořák, Jiří (referee) ; Šeda, Miloš (advisor)
The following diploma thesis focuses on processing of uncertain information in databases. Uncertain information represents vague customer requests during laptop choice in classic shop purchasing. Effort of the work is to develop a modern e-shop application selling laptops, which is based on expert fuzzy system helping customers to choose a laptop without knowledge of technical specifications and current trends.
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Confirmation of temperature chamber and determination of measurement uncertainty
Beníšek, Ondřej ; Šindelář, Michal (referee) ; Šedivá, Soňa (advisor)
The master's thesis deals with the confirmation of temperature chambers, with the greatest emphasis on the determination of standard measurement uncertainty, both by the classical method (GUM) and the Monte Carlo method. It includes the design of a measuring system with data transfer to a computer using the USB communication interface and an analysis of the sources of uncertainty entering the system, which are then practically quantified. To obtain the data, a measuring experiment was carried out in the CVVOZE testing laboratory. The LabView program was used for virtual instrumentation, in which a measuring application was designed and created, which takes care of the collection and processing of measured data. The result of the application is, in addition to recording temperatures from all measured points in the chamber, also the standard uncertainty calculated by the GUM and Monte Carlo methods, including plotting a histogram from the results obtained by both methods in order to compare them. Finally, the achieved results are compared and evaluated.
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Determination of measurement uncertainties of holes in steel components by X-ray computed tomography
Blažek, Pavel ; Šperka,, Jiří (referee) ; Kalasová, Dominika (advisor)
This thesis deals with determination of uncertainties of dimensional measurements in X-ray computed tomography. CT measurement process involves a lot of steps and is affected by a lot of factors, which depend not only on the CT system parameters but also on the measured sample and the operator. All of this influences the resulting uncertainty. Experimental method involving calibrated workpieces allows to determine the uncertainty without perfect knowledge of the influence factors. This method is described in standards ISO 15530-3 and VDI/VDE 2630 2.1. The aim of this work is to experimentally determine the uncertainty of tomographic measurement of dimensions of holes of selected workpiece on a CT device GE phoenix v|tome|x L240. Hence, a demonstration workpiece has been designed and manufactured. The dimensional CT measurements of inner and outer diameters have been performed on this sample. The reference measurement has been performed using a length measuring machine SIP 1002. The uncertainty of measurement depending on penetration thickness of the material has been determined.
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