|
|
Computational modelling of interaction between oscillating vocal folds and air flow
Pavlica, Ondřej ; Matug, Michal (referee) ; Švancara, Pavel (advisor)
Master thesis deals with creating numerical model of the human vocal folds. Calculation algorithm includes interaction between vocal chords and the air flow. Modal analysis of structural and acoustic environment, backround research of vocal folds function and summary of some published overviews of numerical models are parts of this work. Analysis of the results achieved by the numerical simulations and calculations are focused on the pressure and velocity conditions in the areas under vocal folds, between vocal folds and above vocal folds. Movement and stress analysis of individual layers of vocal folds has been made. Impact of tissue thickness on resulting behaviour has been assessed.
|
|
|
Computational modelling of noise inside cabin of aircraft VUT 100 Cobra
Prnka, Jiří ; Houfek, Lubomír (referee) ; Švancara, Pavel (advisor)
This master’s thesis deals with the computational simulation of low-frequency noise inside the cabin of small commercial airplane VUT 100 Cobra. For this low-frequncy range deterministic methods: Final Element Method (FEM) and Boundary Element Method (BEM) are used for simulation of the dynamic behaviour of the object. FEM has been used to compute eigenmodes and eigenfrequences of the structure of the aeroplane cabin and of the acoustic space inside cabin. Then response to harmonic excitation of engine represented by unit forces in place of contact has been computed. Obtained velocities on the surface of the cabin are then used as the basis for the noise calculation inside the cabin using BEM. After that effect of some construction modifications on sound level inside cabin are evaluated by computational modelling.
|
|
|
Computational modelling of function of human vocal folds
Klíma, Jaromír ; Vašek, Martin (referee) ; Švancara, Pavel (advisor)
Master thesis deals with creating of the numerical model of the human vocal folds. Calculation algorithm is designed to include vocal chordsinteraction with the air flow. Analysis of the results achieved by the numerical simulations and calculations are focused on the pressure and velocity conditions in the areas under vocal folds, between vocal folds and above vocal folds. Movement and stress analysis of individual layers of vocal folds has been made. This analysis is limited only for physiological health vocal folds without pathology and disease. Modal analysis of structural and acoustic environment, backround research of vocal folds function and summary of some published overviews of numerical models is part of this work.
|
|
|
Analyses of Mechanical Tasks in ADAMS
Rybár, Šimon ; Švancara, Pavel (referee) ; Hadaš, Zdeněk (advisor)
The aim of this thesis was to create parametric models of technical systems in Adams software. The simulations were made to analyze the systems from kinematic and dynamic point of view. In some cases, the simulation results were compared with the results obtained by the analytic method. The thesis is divided into three chapters. The first defines the area and aims of the thesis. The second one defines multibody system and closely presents the software and its features. The third chapter contains five different examples which demonstrate the abilities of Adams. In the conclusion, own information, overall rating and educational recommendations are summarized.
|
|
|
Influence of exostoses on hearing
Vališová, Šárka ; Švancara, Pavel (referee) ; Pellant, Karel (advisor)
Exostoses are periosteophyte inside the external auditory canal of the human ear. The main objective of this bachelor´s thesis is to determine the potencial impact of the shape modification of the external auditory canal due to occurence of exostoses on the mechanical sound transmission into the internal ear. The task was solved by FEM modelling performed in the ANSYS system. The simple finite element 2D model of the normal human ear has been taken from the diploma thesis B. Ouali: Development of 2D finite element model of human ear (BUT Brno, 2009), the model included the external ear canal, elastic eardrum, otitis cavity with the otitis ossicles and the cavity of the internal ear. The changes simulating exostoses in form of two opposite semicircles were performed. The different size and position of the symmetrical exostoses were studied. The influence of the exostoses on the sound transfer characteristics of the external ear canal was discused. It was processed the set of the audiograms (19 patients). The results of the modelling and the results of the audiology were compared, the preoperativ and the postoperativ stages were considered.
|
|
|
Development of finite element model of human vocal tract and space around the head based on data from computer tomography
Švarc, Martin ; Pellant, Karel (referee) ; Švancara, Pavel (advisor)
This bachelor´s thesis deals with creating a computational model for acoustic wave propagation in vocal tract and the area near the head. The main objective of this work is to map the three-dimensional model of the human head as an additional acoustic environment for more accurate measurement of the human voice on the basis of data from computed tomography, the study of function of the vocal cords, biomechanics of the human voice and an overview of medical imaging techniques suitable for the display of biomechanical models. The grid for finite element method (FEM) will be created from solid geometry of the vocal tract (from the vocal cords to the lips) and the acoustic space near the human head. The grid will be created in order to obtain new knowledge about the different locations of a human head with microphone.
|
|
| |
|
| |
|
| |
|
|
Numerical simulation of videokymographic images from the results of the finite element model
Švancara, P. ; Horáček, Jaromír ; Martínek, T. ; Švec, J. G.
The study presents a two-dimensional (2D) finite element (FE) model of the fluid-structure-acoustic interaction during flow induced self-oscillation of the human vocal folds. The FE model combines the FE models of the vocal folds, the trachea and the simplified human vocal tract shaped for phonation of vowel [a:]. The fluid-structure interaction is solved using explicit coupling scheme with separated solvers for structure and fluid domain. The developed FE model comprises large deformations of the vocal-fold tissue, vocal-fold contact, fluid-structure interaction, morphing the fluid mesh according to the vocal-fold motion (Arbitrary Lagrangian-Eulerian approach), solution of unsteady viscous compressible airflow described by the Navier-Stokes equations and airflow separation during the glottis closure. The effect of lamina propria thickness and material properties on simulated videokymographic (VKG) images of vocal-fold vibrations are analyzed. Such variation of the lamina propria properties can be caused by certain vocal-fold pathologies such as Reinke's edema. The developed FE model can be used to study relations among pathological changes in vocal folds tissue, the resulting VKG images and the produced sound spectra.
|
guest ::
RSS feed.