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Dissipated energy of hard rubbers at dynamic torsional finite straining
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 find the dependency the dissipated energy on the deformation energy. Based on the results of an experiment, a function of dissipation energy of hard rubbers for finite strains using the theory hyperelasticity was proposed herein analogically as a prportional damping for elastic theory. Samples of hard rubber of different hardness (EPDM, Silcone) were dynamically tested on the developed torsional test-rig at different frequencies, amplitudes. First the Mooney Rivlin model (MRM) for a shear case of loading was analytically developed and then MRM constants were attained by fitting of the MRM to the experimental torsion-deformation curve. These constants were used to obtain the deformation energy of the MRM models. The coefficients of hyperelastic proportional damping relating a dissipated energy to a strain energy were evaluated for tested rubbers on the basis of experimental results.
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Experimental modelling of phonation using artificial models of human vocal folds and vocal tracts
Horáček, Jaromír ; Radolf, Vojtěch ; Bula, Vítězslav ; Košina, Jan
The study provides information on experimental research on a complete 1:1 scaled model of human phonation. The model includes human lungs, the trachea, the laryngeal part with artificial vocal folds and the vocal tracts designed for different vowels. The measurement set up enables modelling the time signals not easily measured in humans during phonation as for example fluctuations of the subglottic, laryngeal and oral pressures measured simultaneously with the glottis opening and the glottis area registered by a high-speed camera. The simulation of phonation is performed in the ranges of the airflow rate and the subglottic pressure typical for a normal humans' physiology.
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Proposal of hyperelastic proportional damping as dissipated energy model of hard rubbers
Šulc, Petr ; Pešek, Luděk ; Bula, Vítězslav ; Košina, Jan ; Cibulka, Jan
The paper deals with a stress analysis of hard rubber under large torsion deformations. This study was motivated by effort to find the dependency the dissipated energy on the deformation energy. Based on the results of an experiment, a function of dissipation energy of hard rubbers for finite strains using the theory hyperelasticity was proposed herein analogically as a proportional damping for elastic theory. Samples of hard rubber of different hardness (EPDM, Silicone) were dynamically tested on the developed torsional test-rig at different frequencies, amplitudes. First the Mooney Rivlin model (MRM) for a shear case of loading was analytically developed and then MRM constants were attained by fitting of the MRM to the experimental torsion-deformation curve. These constants were used to obtain the deformation energy of the MRM models. The coefficients of hyperelastic proportional damping relating a dissipated energy to a strain energy were evaluated for tested rubbers on the basis of experimental results.
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Models of Lobachevskij's geometry and possibilities of their use at secondary school
Kosina, Jan ; Kvasz, Ladislav (advisor) ; Jančařík, Antonín (referee)
This thesis Models of Lobachevskij's geometry and the possibilities of their use at secondary school focuses on one kind of non-Euclidean geometries, the Bolyai - Lobachevskij's geometry. The first chapter describes the history of non-Euclidean geometry, shows difficulties of understanding of one publication dedicated to these problems by current students of secondary schools and shows some chosen methods in the didactics of mathematics, especialy the constructivist method. The second chapter is dedicated to elemental concepts of projective geometry, Bolyai - Lobachevskij's geometry and it shows its basic models. It further analyses the specific features of this kind of geometry in Beltrami - Klein's model, especially mutual positions of straight lines. This theses further contains a set of gradual tasks. The third chapter is dedicated to the description of a didactical experiment. In this experiment were students of secondary school acquainted with this theory and tasks, which they solved. Student's solution were writen down and than analysed in the constructivist methodology term in the didactics of mathematics.
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Case Study of Physiotherapeutic Care of a Patient with Rotator Cuff rupture
Kosina, Jan ; Pavlů, Dagmar (advisor) ; Neuwirthová, Svatava (referee)
Title: Case Study of Physioterapeutic Care of a Patient with Rotator Cuff Rupture. Objectives: Main Goal of this Bachelor Thesis is to Present a Case Study of a Patient with Rotator Cuff Rupture. Another Objective is to Create a Complex Theoretical Background Connected to Patient Diagnosis. Methods: Thesis is Divided into Two Parts. First Theoretical Part is Dedicated to an Anatomy, Kinesiology and Biomechanics of the Shoulder Complex, Most Common Injuries of the Shoulder Complex and Possible Treatments which is Conservative, Operative and Physiotherapy Treatment. Examination and Treatment of the Patient Took Place at the Rehabilitační Nemocnice Beroun in the Time Between 9th January 2017 and 27th January 2017. Results: Patient's Health has Been from Both Subjective and Objective Point of view Improved. Especially Muscle Strength has been Increased and Shoulder Complex Position has been Corrected. Keywords: Physiotherapy, Rotator Cuff, Shoulder Complex, Case Study
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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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