Národní úložiště šedé literatury Nalezeno 211 záznamů.  předchozí11 - 20dalšíkonec  přejít na záznam: Hledání trvalo 0.01 vteřin. 
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.
On Finite Element Approximation of Flow Induced Vibration of Elastic Structure
Valášek, J. ; Sváček, P. ; Horáček, Jaromír
In this paper the fluid-structure interaction problem is studied on a simplified model of the human vocal fold. The problem is mathematically described and the arbitrary Lagrangian-Eulerian method is applied in order to treat the time dependent computational domain. The viscous incompressible fluid flow and linear elasticity models are considered. The fluid flow and the motion of elastic body is approximated with the aid of fininite element method. An attention is paid to the applied stabilization technique. The whole algorithm is implemented in an in-house developed solver. Numerical results are presented and the influence of different inlet boundary conditions is discused.
Incompressible and compressible viscous flow with low Mach numbers
Balázsová, M. ; Feistauer, M. ; Sváček, Petr ; Horáček, Jaromír
In this paper we compare incompressible flow and low Mach number compressible viscous flow. Incompressible Navier-Stokes equations were treated with the aid of discontinuous Galerkin method in space and backward difference method in time. We present numerical results for a flow in a channel which represents a simplified model of the human vocal tract. Presented numerical results give a good correspondence between the incompressible flow and the compressible flow with low Mach numbers.
Konečnoprvková 2D formulace vibrací elastické struktury při velkých deformacích
Michálek, Jakub ; Horáček, Jaromír (vedoucí práce) ; Matyska, Ctirad (oponent)
Práce se věnuje numerickému řešení pohybu hlasivky při velkých výchylkách, zatímco dosavadní práce uvažují zpravidla pouze malé výchylky. Uvažovaná geometrie hlasivky odpovídá nejjednodušší situaci fistule, kdy sledujeme jednu izolovanou hlasivku. Hlasivku uvažujeme obecně jako nelineární a neizotropní kontinuum ve 2D prostoru. Pro demonstraci funkčnosti modelu pak numericky simulujeme chování hlasivky s lineární konstituční rovnicí. Hlasivku modelujeme metodou konečných prvků s kvadratickými prvky, a to při statickém a dynamickém zatížení povrchu. Ukazujeme, že pro simulaci deformace hlasivkové tkáně je třeba uvažovat rovnice s velkými výchylkami. Numerickou simulaci hlasivky lze využít např. při konstrukci umělých hlasivek, a při optimalizaci jejich funkce. Porozumění fonačnímu mechanismu je rovněž podstatné pro zjištění příčin onemocnění jako jsou hlasové uzlíky a pro položení vědeckých základů pro foniatrii a pěveckou výuku. Práce je interdisciplinární a skládá dohromady poznatky z mechaniky kontinua, anatomie a pěvecké výuky.
Influence of the velopharyngeal opening on human voice quality
Vampola, T. ; Horáček, Jaromír
The 3D FE models of the nasal cavities and adult female vocal tract were developed from computer tomography (CT) images for vowels /a:/ and /i:/. The interconnections between the oral and nasal cavities were created according to the anatomical literature. The acoustic frequency - modal characteristics of the FE models were studied by the modal analysis considering zero pressure at the lips and nose and the influence of velopharyngeal insufficiency on the first ten formants was evaluated.
Effect of a soft tissue on vocal tract acoustic resonance properties in vocal exercises using phonation into tubes
Radolf, Vojtěch ; Horáček, Jaromír ; Laukkanen, A. M.
Mathematical model is introduced to clarify the influence of the vocal tract soft tissues on the acoustic resonance (formant) frequencies. The influence is studied in the context of voice therapy technique that uses phonation into tubes. Strong acoustc-structural interaction is demonstrated to take place in the vocal tract when it is prolonged by a tube with the distal end in air or submerged 2 cm and 10 cm in water. The numerical results from the model are compared with the resonance frequencies measured in humans.
Experimental investigation of phonation using artificial models of human vocal folds and vocal tract
Horáček, Jaromír ; Radolf, Vojtěch ; Bula, Vítězslav ; Košina, Jan ; Vampola, T. ; Dušková, Miroslava
The contribution presents results of in vitro measurements of voicing performed on originally developed models of the human vocal folds and vocal tract. The designed models are based on CT and MRI measurements of human subject during phonation. The measured phonation (aerodynamic, vibration and acoustic) chacteristics are comparable with values found in humans.
FE modelling of the influence of the lamina propria properties on the vocal folds vibration and produced sound for specific Czech vowels
Hájek, P. ; Švancara, P. ; Horáček, Jaromír ; Švec, J.G.
The developed two-dimensional finite element model of the flow-induced self-oscillation of the human vocal folds is used for solving fluid-structure-acoustic interaction occurring during phonation. The aim is to nalyze the influence of stiffness of superficial lamina propria on vocal folds vibration considering vocal tracts shaped for the vowels [i:] and [u:].
Computation of aerodynamic damping in aeroelastic system based on analytical and numerical approach
Chládek, Štěpán ; Horáček, Jaromír ; Zolotarev, Igor
The paper describes computation of aerodynamic damping and natural frequencies of aeroelastic systems. The damping is a critical parameter for the stability analysis of aeroelastic systems. Structural damping of the system is important for very low fluid flow velocities, however by increasing the flow velocity, the aerodynamic damping dominates in the instability search. The damping can be evaluated in time or in frequency domain. The presented computation of aerodynamic damping consists of two analytical and one numerical approach. The analytical approaches are represented by the well-known pk method and the unsteady panel method. The pk method is based on Theodorsen unsteady aerodynamics and on the computation of complex eigenvalues of the system as functions of the flow velocity. The unsteady panel method enables the computation of the interaction between aeroelastic system and fluid flow. The aerodynamic damping is evaluated in time domain from the system response to given initial conditions. The numerical approach is based on the finite volume method (FVM) modelling the complete fluid-structure interaction (FSI) coupled problem. The aerodynamic damping is also computed from the system response to a given initial condition. The results of the mentioned methods are compared for the profile NACA 0012 with two degrees of freedom (2-DOF) for plunge and pitch motion around an elastic axis.

Národní úložiště šedé literatury : Nalezeno 211 záznamů.   předchozí11 - 20dalšíkonec  přejít na záznam:
Viz též: podobná jména autorů
6 HORÁČEK, Jakub
1 Horáček, J.
6 Horáček, Jakub
13 Horáček, Jan
8 Horáček, Jaroslav
23 Horáček, Jiří
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