National Repository of Grey Literature 219 records found  beginprevious207 - 216next  jump to record: Search took 0.01 seconds. 
Design of an experimental set up for studies of 2D unsteady aeroelastic phenomena by optical methods
Horáček, Jaromír ; Luxa, Martin ; Vaněk, František ; Veselý, Jan ; Vlček, Václav
The report is an introductory study in the design of optical methods for visualization of unsteady flow fields near a vibrations profile with two degrees of freedom. The report contains description of the aeroelastic model, the results of measurements of dynamic and aeroelastic characteristics of the model in the wind tunnel and design of methodology for the optical measurements including schemes of special synchronization electronic circuits and the overall device connection arrangement.
Dynamic properties of some physical models of artificial vocal folds
Šidlof, Petr ; Veselý, Jan ; Horáček, Jaromír
The report presents results from measurements of acoustic and vibratory characteristics of six originally designed artificial vocal fold prototypes made of silicon rubber and based on various aeroelastic principles. During measurements, the dynamic subglottal pressure and output acoustic pressure were recorded. Spectral analysis of the signals was performed, and where the construction permitted, the vibrations were also observed by means of videostroboscopy. For two prototypes a shape and material optimization is possible with the aid of the mathematical models developed in IT AS CR.
Dynamická analýza tenkostěnné kruhové desky ovlivněné interakcí s kapalně-plynným prostředím v elastické válcové kavitě
Horáček, Jaromír ; Griffond-Boitier, F.
The study deals with the free vibration analysis of a cylindrical thick-walled cavity filled by a gas axially bounded at one end by a liquid interface and by a thin elastic disc at the other end. Numerical calculations performed are compared with theoretical solution and with the experimental results. The interaction between water and air in a rigid cavity was also studied. The influence of a compliance of the rigid cavity on the natural frequencies was taken into account for comparison with experimental data.
Simulace lidského hlasu s využitím MKP modelu vokálního traktu
Horáček, Jaromír ; Griffond-Boitier, F.
Finite element models of male vocal tract for Czech vowel /a/ are analyzed and used for numerical simulation of phonation. The models were designed from the MRI the subject during phonation. The acoustic signals for the vowel /a/ are simulated using the transient analysis. For excitation of the supraglottal spaces the intraglottal pressure or airflow rate generated by the aeroelastic model of vocal folds self-oscillations is used. The frequency and time response functions calculated near the lips and in front of the mouth are compared with acoustic measurements.
Dynamic characteristics of the human vocal tract influenced by the cleft palate
Vampola, T. ; Horáček, Jaromír ; Bauma, V.
Finite element models of supraglottal tract for Czech vowels /a/ and /u/ are analyzed considering the cleft palate. Performed acoustic modal analysis is focused on investigation of the influence of the area of cleft palate on the formant frequencies F1-F3. The results for the vowel /a/ indicate, that after a small jump of the acoustic natural frequencies for a very small cleft the frequencies F1 and F2 are influence by increasing size the cleft only very slightly. The influence of the cleft on the phonation of the vowel /u/ is considerable higher.
3-D FE model of the human vocal folds for dynamic computations
Vampola, T. ; Horáček, Jaromír
The article describes the design of a 3D finite element (FE) model of real human vocal folds in a defined phonation position. The model was developed from the CT images of the plaster casts obtained by a special procedure during experiments with the excised human larynges. The model is determined mainly for studies of dynamical stresses in the vocal fold tissue during vocal folds collisions.
Numerical modelling of effect of tonsilectomy on production of Czech vowels /a/ and /i/ based on FE model of human vocal tract
Švancara, Pavel ; Horáček, Jaromír
Finite element models of the human vocal tract for the Czech vowels /a/ and /i/ were modified by adding acoustic spaces that occurs after tonsilectomy. The resonant characteristics of the models were studied and then the pronunciation of the vowels was simulated. The results show that tonsilectomy causes frequency shift of 3rd (~180 Hz) and 4th (~120 Hz) formants to lower frequencies for vowel /a/ and frequency shift down of 2nd, 4th and 5th formant for vowel /i/ (all ~100 Hz).
Dynamic properties of some physical models of artificial vocal folds
Šidlof, Petr ; Veselý, Jan ; Horáček, Jaromír
The paper presents results of measurements of acoustic and vibratory characteristics of several artificial vocal fold prototypes based on various principles. During measurements the dynamic subglottal pressure and output acoustic pressure were recorded. Spectral analysis of the signals was performed, and where the construction permitted, the vibrations were also observed by means of videostroboscopy. In some cases, a computer-modelling-based shape and material optimizations is possible with the aid of the mathematical models developed in IT AS CR.
Numerické řešení proudění kolem vibrujícího leteckého profilu
Honzátko, R. ; Horáček, Jaromír ; Kozel, K.
The work deals with numerical solution of 2D inviscid and viscous incompressible flow over the airfoil NACA 0012 in a channel. The finite volume method with cell-centered schemes at quadrilateral C-mesh is used. Governing equations are the Euler equations in the case of inviscid flow and Navier-Stokes equations in the case of viscous flow. The small disturbance theory applied to a numerical solution of unsteady flow is mentioned and the brief introduction is also given to the ALE method.
Fyziologické údaje získané z aeroelastického modelu kmitání lidských hlasivek
Horáček, Jaromír ; Laukkanen, A. M. ; Šidlof, Petr
The results of the numerical simulations show that the aeroelastic model for vocal fold self-oscillations corresponds well with the existing clinical data and it thus gives the possibility to study independently various phonation related variables that may in living subjects be obscured by the co-existence of many variables. Furthermore, the model of course naturally gives the possibility to study also such variables that are impossible to study in living subjects.

National Repository of Grey Literature : 219 records found   beginprevious207 - 216next  jump to record:
See also: similar author names
6 HORÁČEK, Jakub
1 Horáček, J.
6 Horáček, Jakub
18 Horáček, Jan
1 Horáček, Jan Jiří
11 Horáček, Jaroslav
25 Horáček, Jiří
1 Horáček, Jonáš
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