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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.
51

Diagnostika vibrací elektrických strojů / Vibration diagnostics of electrical machines

Lexa, Jakub January 2016 (has links)
This thesis deals with vibration diagnostics of electrical machines. The thesis describes vibrations and their measurement. The next section concernes the diffrent modes of elctrical machines. Vibration of machines are divided into electrical causes and mechanical causes. Practical part deals with the measurement of vibration on the machines and their subsequent analysis. The result of the practical part is determining the fault of the measured induction motors.
52

Virtuální prototypy hnacích ústrojí / Virtual Prototypes of Drivelines

Janoušek, Michal January 2016 (has links)
The thesis deals with computational modelling of heavy duty off-road vehicle driveline components. The thesis is divided to two main parts. The first part deals about modal analysis of selected driveline components. MBS computational study was performed based on modal analysis results. The second part of thesis deals with experimental verification of computational model. Pass-by noise and vibration measurement was performed. Measured signals were processed in frequency domain to find noise and vibration sources.
53

Analýza dynamických účinků působících na železniční výhybky / Análisis de los efectos dinámicos que actúan sobre los cambiaviás férreos

Vukušičová, Daniela January 2017 (has links)
This thesis is focused on measurement and analysis of dynamic effects on railway turnouts. Two same-type turnouts with different fastening elasticity were chosen. My attention was focused mainly on the crossing part of the turnout, where the highest dynamic impacts occur. The point of the thesis is comparison of the crossing part of turnouts in term of dynamic behaviour and assessment of influence of soft rail pads on spread of dynamic energy through the construction. A part of the thesis is choice of methodology of the measurement and proposal of convenient mathematical apparatus for analysing of the dynamic effects on crossings.
54

Srovnávací analýza sexuálního a agonistického chování gekonů čeledi Eublepharidae / Comparative analysis of sexual and agonistic behaviour in eyelid geckos (Eublepharidae)

Rauner, Petr January 2014 (has links)
Sexual selection is one of main selective pressure affecting body size, and subsequently leads to the evolution of sexual size dimorphism (SSD). The eyelid geckoes, family Eublepharidae, are a monophyletic group with considerable variability in SSD, including both male-larger and female-larger species. In general, it was supposed that eyelid geckos are highly variable in presence of male combats and in complexity of male pre-copulatory behaviour, and that this variability in this conspicuous male behaviour may lead to differences in SSD. The aim of this study was to reveal relationships between the direction of SSD and presence/absence of tail vibration during precopulatory phase and male combat behaviour. Using behavioural testing, it was revealed that male combats are present in all tested species, even in species, where the absence of such behaviour was supposed so far. In several species, the strong effect of seasonality to male aggression was observed, which may play a role in the evolution of SSD. The evolutionary changes in the presence/absence of tail vibration during precopulatory phase were independent on changes in the direction of SSD, the presence of tail vibration seems to be ancestral state for these lizards. During the evolution of this group, the tail vibrations disappeared four...
55

Identifikace změn mechanických vlastností axiálního systému člověka v důsledku zátěžového a relaxačního režimu / Identification of changes in mechanical characteristics of human axial system as a result of loading and relaxation regime

Van der Kamp Kloučková, Kateřina January 2013 (has links)
Problem: A lot of attention is given to the safety of the driving and the possibility to register fatigue of the drivers. Driving cars is monotony and static. Vibration loading, which causes changes in the axial system. This causes discomfort and fatigue to drivers after some time of exposure to the loading. Hypothesis: It is possible to prove the changes of mechanical characteristics (indicators) of the axial system using the TVS (transfer vibration through spine) method. By using TVS method before and after different types of loading or before and after relaxation it is possible to detect changes of the viscoelastic properties. This can be done by checking changes in the way of waves transfer through the axial system of the observed participants. Objective: Verify the possibility of use of TVS method to register changes of the viscoelastic characteristics of the axial system. Method: The TVS was chosen as a detection method. The method is based on the use of five-msec semi-bandwidth γ pulse stimuli and consequent application of continuously changing harmonic stimuli which periodically differ between 5Hz and 160Hz to the vertebrae C7 and L5. This wave is carried through the axial system and its acceleration on the spinous processes between C7 and S1 is scanned with the help of accelerometric...
56

Vliv vibrací stroje Power Plate na kontrakci m. levator ani. / Influence of Power Plate machine vibrations on m. levator ani contraction.

Svozilová, Barbora January 2016 (has links)
9 Abstract Title: Influence of Power Plate machine vibrations on m. levator ani contraction. Objectives: In my thesis I would like to follow up on my bachelor`s thesis in which I was analyzing the importance of exercise on the Power Plate machine from a theoretical point of view. I set the objective of my thesis, in co-operation with professionals in this area, to find out whether Power Plate machines have any impact on the pelvic floor contractions, especially on the m. levator ani. Methods: Theoretical part of my thesis was conducted using the research (exploration of facts) method. For theoretical input I mainly used my bachelor`s thesis which was being followed up with. Majority of studies regarding WBVT (whole body vibration training) influence on human body is available from foreign sources. The practical part of my research was conducted via the quantitative quasiexperimental method. The works was further performed with use of the explanation (empirical and generally theoretical) methods and interpretation methods. For the data analysis were used the basic descriptive statistics, analysis of variance with repetition with Geisser-Greenhouse adjustment and paired t-test. Interpretation method was used to generalize the research outcomes, to confront them with existing knowledge, and to debate their...
57

Metody analýzy vibračních signálů / Methods of analysis of vibration signals

Sivera, David January 2017 (has links)
The aim of the thesis is to focus on the different methods of analysis of vibration signals. Focusing on the physical fundamentals of vibrations and a description of their origin in an electrical machine. Describe the vibration sources from mechanical across the electromagnetic to the aerodynamic. Defining the current defects of electric machines and sensors suitable for the measurement of vibrations in an electric machines. Introduction to the methods of analysis of vibration signals in the time and frequency domain. Then using some of these methods for the analysis of vibration signals measured asynchronous motors with different manufacturer defined production defect. The conclusion is composed from the comparison between measured and analyzed results.
58

Identifikace změn mechanických vlastností axiálního systému člověka v důsledku zátěžového a relaxačního režimu / Identification of changes in mechanical characteristics of human axial system as a result of loading and relaxation regime

Van der Kamp Kloučková, Kateřina January 2013 (has links)
Problem: A lot of attention is given to the safety of the driving and the possibility to register fatigue of the drivers. Driving cars is monotony and static. Vibration loading, which causes changes in the axial system. This causes discomfort and fatigue to drivers after some time of exposure to the loading. Hypothesis: It is possible to prove the changes of mechanical characteristics (indicators) of the axial system using the TVS (transfer vibration through spine) method. By using TVS method before and after different types of loading or before and after relaxation it is possible to detect changes of the viscoelastic properties. This can be done by checking changes in the way of waves transfer through the axial system of the observed participants. Objective: Verify the possibility of use of TVS method to register changes of the viscoelastic characteristics of the axial system. Method: The TVS was chosen as a detection method. The method is based on the use of five-msec semi-bandwidth γ pulse stimuli and consequent application of continuously changing harmonic stimuli which periodically differ between 5Hz and 160Hz to the vertebrae C7 and L5. This wave is carried through the axial system and its acceleration on the spinous processes between C7 and S1 is scanned with the help of accelerometric...
59

Ovlivnění posturální stability hráčů tenisu věkové kategorie 11- 13 let fyzioterapeutickou intervencí cvičením s Propriomedem / The influence of physiotherapeutic intervention with Propriomed on postural stability of 11-13 years old tennis players

Bednarzová, Barbora January 2018 (has links)
Title: The influence of physiotherapeutic intervention with Propriomed on postural stability of 11-13 years old tennis players Objectives: The main aim of this thesis is objectivize the influence of physiotherapeutic intervention involving exercise with Propriomed on the success of strokes and speed of the swing phase of 11-13 years old tennis players. Methods: Teoretical part is composed like a recherche in which are informations that make base fot the practical part. For the practical part was made experimental study which contains sample of 17 probands in age between 11-13 that are active tennis players for more than 5 years. Pobands was divided into intervention group and control group. Intervention group had training with Propriomed once a week. Main task of study was analysis of succes rate and speed of the swing phase of different tennis shots before and after physiotherapeutic intervention with Propriomed and comparing results of both groups. Results: In beckhand shot was observed statistically significant difference after finishing first intervention. It is possible to claim that training with Propriomed positively influence precision of the backhand shot in a short term. Proband reached the best results of succes rate of forehands after last measurement. From that we could claim that...
60

Výpočtové modelování dynamiky převodových ústrojí v prostředí MBS / Multi-Body Computational Modeling of Transmission Dynamics

Líčeník, Adam January 2021 (has links)
This diploma thesis is focused on compiling a computational model of the transmission of a Zetor Forterra HSX tractor in the Multibody software MSC ADAMS environment. It analyses the issue of creating gears in terms of vibration and noise. The thesis describes the creation of computational model which is used for simulation of the load conditions during tractor operation. The methodology is applied to a single-stage gearbox in which is verified. Then it is used on a model of a real tractor gearbox. The response of the input load conditions is projected during the forces in the engagement of the gears which are transmitted to the bearings.

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