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Weight transfer during the putting stroke
Kosina, Jan ; Gryc, Tomáš (advisor) ; Hráský, Pavel (referee)
Title Weight transfer during the putting stroke Objectives Description of weight transfer during the putting stroke and comparison of interindividual and intraindividual stability due to parametres accuracy and weight transfer. Methods Theory was build up by researching method alongside with studiing technical literature. Testing group consisted of professional golfers. Weight transfer was measured by two plattens KISTLER a kinematics of movement was observed by kinematic analysartor CODA motion system. The analysis of interindividual and intraindividual stability was based on data collected during the testing of professional golf players. Results High interindiviual and intraindividual stability of execution was proved due to parametres weight transfer and accuracy. It was proved that capability of accuracy and stability of execution weight transfering is decreasing alongside with longer distance. For description of weight transfer critical phazes of movement were estabilished. By the measurement was discovered how the weight is transferred during the putting stroke. Key words Golf, weight transfer, putting stroke, force effect, accuracy
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Evaluating the amount of physical activity of football players at grade level.
Kosina, Jan ; Kokštejn, Jakub (advisor) ; Frýbort, Pavel (referee)
Bachelor thesis "Evaluating the amount of physical activity of football players at grade level" deals with finding new knowledge concerning the size and composition of the physical activity of adolescent football players. In the theoretical part are being collected knowledge about physical activity and health recommendations concerning the composionfor the age group of adolescents. Amount of physical activity was measured by heart rate sensor, accelerometers and a written record. The evaluation, which is given in the final part of the thesis shows that adolescent football players at grade level are below health recomendations for daily energy expenditure in the prevailing numberof days of the week. In cotrast, in the days when ongoing trining units, they exceed recommendations several times. Regarding the average lenght of sleep, it was found, that the majority of players younger from both categories exceeds recommendations for their age while the results of most players of the older dategory correspond health recommendations.
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Quaternions and Möbius transformations in dimension 4
Kosina, Jan ; Lávička, Roman (advisor) ; Krump, Lukáš (referee)
In this work we describe transformations of the 3-dimensional and the 4- dimensional Euclidean space. First we show how one can elegantly describe re- flections and rotations in these dimensions using quaternions and we prove 2 structural theorems concerning the connection between the group of unit qua- ternions and the special orthogonal groups SO(3) and SO(4). Next we recall a part of the conformal mapping theory, which we use later in the description of the Möbius transformations. We define the Möbius transformations in dimension 4 as compositions of an even number of spherical inversions and reflections. We show that one can describe them also in dimension 4 as linear fractional trans- formations in an analogous way as in dimension 2, if we use quaternions instead of complex numbers. We then outline a classification of Möbius transformations into elliptic, loxodromic and parabolic classes and in dimension 4, we describe what each class looks like. 1
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The evaluation of critical factors for the BTT method measurement
Maturkanič, Dušan ; Košina, Jan ; Hodboď, Robert
The report describes an analysis of critical factors occurred during the Blade Tip-Timing method measuring. These factors are represented by speed fluctuation of model turbine wheel and accuracy of sensors of the vibrodiagnostic system. This analysis is focused on evaluation and comparison of these items in different conditions. Subsequently, the results can be used for the simulations of vibration of turbine blades.
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Experimental analysis of torsion vibration of hard rubbers under large deformation
Šulc, Petr ; Pešek, Luděk ; Bula, Vítězslav ; Cibulka, Jan ; Košina, Jan
The paper deals with a stress analysis of hard rubber under large torsion deformations. This study was motivated by effort to enhance the theoretical background for experimental evaluation of material behaviour of hard rubbers on our test rig. First the Mooney Rivlin model (MRM) for shear case of loading was developed and then MRM constants were attained by fitting of the MRM to the experimental torsiondeformation curve. Then the tuned MRM cylindrical model was tested under torsion loading for evaluation of stress state. Besides the radial distribution of shear stress and strain the attention was paid to evaluation of axial stresses. It could help to assess the influence of the tension stresses on the tangential deformations of the test sample during large torsion.
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Additional axial stress of rubber cylinder at torsion deformations and large strains
Šulc, Petr ; Pešek, Luděk ; Bula, Vítězslav ; Cibulka, Jan ; Košina, Jan
The paper deals with a stress analysis of hard rubber under large torsion deformations. This study was motivated by effort to enhance the theoretical background for experimental evaluation of material behaviour of hard rubbers on our test rig. First the Mooney Rivlin model (MRM) for shear case of loading was developed and then MRM constants were attained by fitting of the MRM to the experimental torsion-deformation curve. Then the tuned MRM cylindrical model was tested under torsion loading for evaluation of stress state. Besides the radial distribution of shear stress and strain the attention was paid for evaluation of additional axial stresses. It helps to assess the influence of the tension stresses on the tangential deformations of the test sample during large torsion strains.
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Stress analysis under torsion loading hard rubber for a large deformation and hyperelastic behaviour
Šulc, Petr ; Pešek, Luděk ; Bula, Vítězslav ; Cibulka, Jan ; Košina, Jan
The paper deals with a stress analysis of hard rubber under large torsion deformations. This study was motivated by effort to enhance the theoretical background for experimental evaluation of material behaviour of hard rubbers on our test rig. First the Mooney Rivlin model (MRM) for shear case of loading was developed and then MRM constants were attained by fitting of the MRM to the experimental torsion-deformation curve. Then the tuned MRM cylindrical model was tested under torsion loading for evaluation of stress state. Besides the radial distribution of shear stress and strain the attention was paid for evaluation of axial stresses. It could help to assess the influence of the tension stresses on the tangential deformations of the test sample during large torsion.
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Measurement of modal and damping behavior of bladed disc with rhombic shroud
Pešek, Luděk ; Košina, Jan ; Cibulka, Jan
The aim of the work was modal analysis of the bladed disc with the rhombic shroud in a range up to 8kHz. The eigenfrequencies and corresponding damping ratios with respect to a number of nodal diameters were to evaluate. To obtain the maximal amplitude excitation, different types of actuators for lower frequency (up to 5 kHz) and higher frequency (above 5 kHz) ranges were used. The responses of the blades were measured by miniature accelerometers during the swept harmonic excitation. The result of the modal analysis are presented in a form of SAFE diagrams. The crossing and veering of dispersion curves appear in the SAFE diagram. It causes excitation and separation of modes very complicated problem from the identification point of view. Despite these obstacles the major part of the seeking resonances in the defined frequency range were successfully excited and identified.
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