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Experimentální výzkum odporu rotačně se pohybující kulové částice
Lukerchenko, Nikolay ; Kvurt, Y. ; Chára, Zdeněk ; Vlasák, Pavel
Saltatory solid particles conveyed by fluid impact a channel bed from time to time. As a result of the collision the particles receive angular velocity, which gradually decreases with time. For numerical simulation of saltation it is necessary to know values of the drag rotation coefficient. In this paper experimental results of the rotating spherical particles moving in water are described. The rubber spherical balls with density near that of water were used; each of them was speeded up in a special chute that ensured that the particle rotated in a given plane. Values of the drag coefficient of the rotating spherical particle were determined in a dependence on rotation particle Reynolds number
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Analysis of turbulent flow in curved channels and diffusers
Příhoda, Jaromír ; Sedlář, M.
Numerical simulation of flow through curved channels and diffusers of rectangular cross section carried out by means of software CFX-TASCflow was focused on the development of secondary flow and the onset of separation region. Turbulent flow through plane diffusers of rectangular cross section with area ratio AR=1.5 was studied. Further, the effect of the inner wall curvature radius on the flow and losses in diffusers was studied. Results were compared with experiments in water channel.
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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.
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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.
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Modelování interakce kardiovaskulárního a respiračního systému
Převorovská, Světlana ; Maršík, František
The real cardiovascular and respiratory system in the model developed in the IT CAS is approximated by four segments of pulsating heart and twenty two vascular segments of pulmonary and systemic circuits including the coronary and bronchial circuits. Respiratory processes are considered at the level of pulmonary, tissue and brain segments. The interaction between the both systems is modelled by baroreflex and chemoreflex control loop.
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Oceňování opcí pomocí simulačních metod
Marková, Iva ; Dlouhý, Martin (advisor) ; Kuncová, Martina (referee)
Obsahem této práce je popis problematiky opcí. Stěžejním cílem této práce je získat reálný odhad hodnoty opce. K ocenění opcí bude použit základní Black-Scholesův model, který bude rozvinut o vliv dividend. Oceňování je založené na mnohokrát opakované předpovědi budoucí hodnoty podkladové akcie. Tato metoda se pokouší napodobit skutečnou situaci pomocí numerické simulace Monte Carlo.
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