|
|
Modeling of airflow through the human vocal tract during voice production
Kučera, Marek ; Hájek, Petr (referee) ; Švancara, Pavel (advisor)
This bachelor's thesis deals with computational modeling of air flow through the human vocal tract during voice production. In the theoretical part, the anatomy of the respiratory system, the function of the human vocal folds, the biomechanics of the human voice and the flow theory are briefly described. Subsequently, an overview of approaches to computational modeling of voice production is presented. The practical part describes the creation of 2D models of the trachea and vocal tract with different settings of the vocal folds. A suitable mesh of finite volumes was created. Stationary flow was solved and analyzed in the ANSYS Fluent program. A suitable time step was determined for non-stationary flow and the results were subsequently analyzed. At the end, the non-stationary flow with the prescribed movement of the vocal folds is solved.
|
|
|
Analysis of Modal Shapes and Natural Frequencies of Real-Shaped Vocal Fold
Horčic, Václav ; Švancara, Pavel (referee) ; Hájek, Petr (advisor)
This bachelor's thesis deals with the modal analysis of a model based on a 3D scan of the human vocal cords. This is a model solved by the finite element method, where the value of the first natural frequency roughly corresponds to the value of the fundamental frequency of female vocal folds. The research part of the thesis is devoted to an overview of finite element models of the geometry of the vocal cords, which is followed by a brief description of the anatomy and physiology of the human speech system together with the theory of the formation of the human voice. The finite element model is created using a 3D scan of the vocal folds in the commercial program ANSYS Workbench, in which it is solved by the finite element method.
|
|
|
Modeling of Interaction between Lumped Element Model of the Vocal Fold and Fluid Flow
Řeřuchová, Ivana ; Švancara, Pavel (referee) ; Hájek, Petr (advisor)
The thesis belongs to the branch of biomechanics of human voice and bioacoustics. It deals with the modelling of the vocal cords in interaction with the air flow and the vocal tract. Specifically, it involves two-mass and three-mass body-cover models. The interaction is solved using the finite-difference method, the vocal cord oscillation is represented by the equations of motion, the flow is simulated by Bernoulli's equation, and the acoustics is implemented using an electro-acoustic analogy as an acoustic circuit. The thesis also includes the basics of laryngeal anatomy, the physiology of the human voice, and a review of previously published material models of the vocal cords, i.e., models with a low number of degrees of freedom.
|
|
|
Computational modelling of blood flow in the carotid artery with serial stenosis
Lukáš, Petr ; Hájek, Petr (referee) ; Švancara, Pavel (advisor)
The aim of this bachelor's thesis is to analyse the effect of double stenosis on flow and stress characteristics in the carotid artery. First, based on the stated literature, a literature search is conducted regarding blood flow in the arterial system. Then, the procedure of creating idealized models of an artery with double stenosis and the procedure of mesh creation and numerical solution are described. The models have different size of the stenosis and different distance between stenosis. In the final stage, the results are analysed first for stationary flow, then one model is selected on which is performed the analysis for pulsating flow. Analytical calculation of pressure drop and comparison with numerical calculation is also part of this work.
|
|
|
Optimization of modal properties of the body in the air flow
Matějka, Jan ; Švancara, Pavel (referee) ; Skalka, Petr (advisor)
The bachelor thesis deals with dynamic analysis of the rod body, which is excited by the Karmán vortices. In this thesis a method of countermeasure is also verified, which could be possibly used in order to supress the state of resonance in the body and which could minimalize the influence of the Karmán vortices on the structure. This method consists in change of the mass in specific parts of the body in order to change modal properties of this body. The main goal of the thesis is to find suitable configurations of the mass distribution depending on air flow velocity for purpose of minimalization the influence of the Karmán vortices on the construction. This is achieved by optimization of modal properties. The optimization is based on results of harmonic analysis and is considering possibility of practical use.
|
|
|
Modal analysis of vocal folds models with descrete parameters
Lekeš, Filip ; Švancara, Pavel (referee) ; Hájek, Petr (advisor)
Bachelor’s thesis deals with modal analysis of computed models of human vocal folds. It’s about finite element and analytical model where values first eigenfrequencies come under male vocal folds. Research part applies to biomechanics of vocal the human voice, which is followed by an overview of computational models. Finite element model is completely created and solved by ANSYS Workbench commercial program, which uses the finite element method to simulate a problem. Solution of analytical model uses freely available Python programming language. Analysis of the results and comparison of approaches belong to main objectives of the presented work. The proposed analytical model can serve future students for detailed understanding of human vocal oscillations.
|
|
|
Simulation modelling of blower system
Gajdík, Michal ; Švancara, Pavel (referee) ; Hadaš, Zdeněk (advisor)
This diploma thesis is focused on simulation modeling of Roots blowers, which are produced by Kubicek VHS company. First part of this thesis is about oscillations and its damping. In following phase are analyzed each methods realization and control of oscillation damping. Second part of this thesis is focused on Roots blower modelling with rigid and flexible parts and its verification. Output of this thesis is dynamic analysis of Roots blower 3D28C. On attached CD are program annex and project in Adams MSC. Aim of this thesis is proposing adjustments, which would reduce noise and vibration of analyzed machine.
|
|
|
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.
|
|
|
Noise and vibrations of roots blowers
Smrček, Martin ; Hájek, Petr (referee) ; Švancara, Pavel (advisor)
This thesis is concerned with the spread of noise in the housing sets blowers, blower vibration, due to the shape of the geometry of the individual parts of the blower and the design of a suitable discharge muffler in order to achieve the highest possible attenuation. Analysis blower and silencer discharge was conducted using the finite element simulation ANSYS 15.0
|
|
|
Computational modeling of the interaction of flowing blood with the artery tube with the atheroma
Freiwald, Michal ; Jagoš, Jiří (referee) ; Švancara, Pavel (advisor)
Předložená diplomová práce se zabývá interakcí mezi proudící krví a krční tepnou, obsahující aterosklerotický plat, za pomoci konečnoprvkové fluid-structure interaction analýzy. První část práce obsahuje souhrn teoretických poznatků, sestávající z kardiovaskulárního systému, cév, souvisejících konstitutivních modelů, reologie krve a úvodu do teorie proudění. Dále je v práci obsažen stručný souhrn současného poznání výpočtového modelování v této oblasti, s důrazem na strukturní a fluid-structure interaction analýzy v oblasti krční tepny, a na použité konstitutivní modely. Experimentální část se soustředí na tvorbu zjednodušeného modelu krční tepny, obsahující aterosklerotický plat, a na tvorbu odpovídajícího modelu krve. Oba modely poté společně vstupují do fluid-structure interaction analýzy, která si klade za cíl pochopit důsledky pulzujícího toku krve na stěnu tepny a na růst aterosklerotického plátu; primárními zkoumanými veličinami jsou první hlavní napětí na stěně tepny, celková deformace stěny tepny, časově zprůměrovaná hodnota smykového napětí na stěně tepny a oscilační smykový index. Všechny výsledky jsou porovnány napříč několika typy analýz, tak aby bylo možné zhodnotit rozdíly a důsledky zvoleného přístupu. Součástí práce je také zjednodušená parametrická studie, která porovnává vliv rostoucího procenta stenózy na vyhodnocované veličiny. V poslední částí práce jsou zhodnoceny výsledky, její limitace a další možnosti výzkumu v této oblasti.
|
guest ::
