National Repository of Grey Literature 24 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Deformation energy of Yeoh hyperelastic model and constant hyperelastic proportional damping
Šulc, Petr ; Pešek, Luděk ; Bula, Vítězslav ; Košina, Jan ; Cibulka, Jan
The paper deals with a proposal of the dissipated energy of hard rubbers as a function of the deformation energy expressed by the Yeoh hyperelastic model. Then the deformation energy may be dependent only on the first invariant of deformation. Based on the experiment, a “hyperelastic proportional damping” (HPD) is proposed for hard rubbers under finite strains. It is analogical to the model of proportional damping in the elastic theory, i.e. the dissipated energy is proportional to the deformation energy multiplied by the frequency of dynamic harmonic loading. The Yeoh model is chosen since the deformation function is dependent only on the first strain invariant for a description of the simple shear of a surface cylinder. The constants are used to an enumeration of the deformation energy of the Yeoh model for the specific cases of tested rubbers. The coefficients of hyperelastic proportional damping are evaluated on the basis of experimental results,too.
Acoustic characteristics of 3D human vocal tract model with nasal cavities – preliminary experimental results
Radolf, Vojtěch ; Horáček, Jaromír ; Košina, Jan ; Vampola, T.
Acoustic resonance characteristics of 3D human vocal tract model with nasal and paranasal cavities were measured in three different ways: The excitation was realized by (1) self-oscillating vocal folds replica, (2) by a swept harmonic signal from an earphone placed instead of the vocal folds and (3) by a white noise signal from a loudspeaker located in front of the open mouth of the model. Resulting resonance frequencies are comparable for all excitation signals. These experiments were carried out to verify a complex mathematical model.
Experimental investigation of acoustic characteristics of 3D human vocal tract model with nasal cavities
Radolf, Vojtěch ; Horáček, Jaromír ; Košina, Jan ; Vampola, T.
The following experiments were carried out to be later used in the verification of a complex\nmathematical model of human voice production. Acoustic resonance characteristics of a 3D human voca tract model without and with nasal and paranasal cavities were measured in two different ways: The excitation was realized by (1) self-oscillating vocal folds replica and (2) by sine-tone sweeps from an earphone placed instead of the vocal folds. The resulting resonance and antiresonance frequencies were found to be comparable for both excitation signals.
Analysis of the turbine wheel model vibration
Voronova, Evgeniya ; Maturkanič, Dušan ; Procházka, Pavel ; Hodboď, Robert ; Košina, Jan
The paper describes the verification tests which were performed for 2000 rpm. Determined effects of vacuum on wheel vibration at 100 rpm and at \n500 rpm. Compare measurements at different speeds, with free oscillation or forced oscillation.\n
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.
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.
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.
Rotary laser vibration laboratory
Maturkanič, Dušan ; Procházka, Pavel ; Voronova, Evgeniya ; Košina, Jan
The rotary laser vibration laboratory started the test operation at the Institute of Thermomachanics AS CR, v.v.i. at the end of 2015. The facility enables the research of high power turbomachines rotary bladed wheels. The paper describes the verification tests which were performed and focused on the equipment parameters at different conditions.
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.
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

National Repository of Grey Literature : 24 records found   1 - 10nextend  jump to record:
See also: similar author names
2 KOŠINA, Jiří
5 Kosina, Jan
2 Kosina, Jiří
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