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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.
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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.
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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.
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FE heat conduction modeling of Rubber segment at mechanical harmonic excitation
Šulc, Petr ; Pešek, Luděk
This contribution deals with the numerical finite element modeling of rubber sample temperature field at the harmonic mechanical loading when the heat generated by absorbed mechanical energy is substituted by the constant heat rate input. As the study case a segment of the rubber-damped railway tram wheel was chosen. This segment was experimentally tested and the results were used for tuning the parameters of the FE model of heat conduction and transfer in program ANSYS 6.1.
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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.
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Dynamical coupling between vibrating impact system and source of excitation
Půst, Ladislav
Oscillations of 1DOF mechanical system containing one-sided weak or hard stop excited by means of a spring and a cam driven by a motor with limited power and limited inertia are investigated. Records of transient oscillations when passing through the resonance zone with increasing input energy into the motor show the retardation of frequency-increase in front of the resonance peak and the acceleration of frequency sweep at the jump in behind-resonance zone. The influence of clearance between the vibrating system and the stop, as well as of its stiffness and damping is investigated, too.
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