Ústav termomechaniky

Nejnovější přírůstky:
2019-03-28
15:08
Dynamics of Machines and Mechanical Systems with Interactions : DYMAMESI 2018
Zolotarev, Igor ; Pešek, Luděk ; Kozieň, M.
The Colloquium Dymamesi is continuing near the 20 years history of two conferences Dynamics of Machines and Interaction and Feedbacks. From 2017 the Colloquium is organized within the Czech-Polish (IT ASCR Prague & CUT Crakow) collaboration and the first one was held in CUT in Cracow. The prezentations were divided into the three sections: dynamics of machines, interactions and energetics. The Colloquium DYMAMESI 2018 was for the first time supported also by Programme Strategy 21 (AV21).\n

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2019-03-28
15:08
Aerodynamic transfer of energy to vibrating vocal folds for different driving mechanisms
Valášek, J. ; Sváček, P. ; Horáček, Jaromír
This paper studies the mutual energy transfer between the fluid flow, described by incompressible Navier-Stokes equations, and the elastic body represented by vocal folds. The aerodynamic energy transfer function describes the amount and more importantly the sign of the energy exchange. It determines if the vocal fold vibrations are self-excited or prescribed.The energy transfer function is studied for three different driving mechanisms introduced by different inlet boundary conditions (BC). The most frequently used inlet BCs for incompressible model of fluid flow approximated by the finite element method are either Dirichlet BC giving the inlet velocity or do-nothing type of BC prescribing the pressure difference between the inlet and the outlet. Since the numerical simulations with both aforementioned BCs do not provide results observed experimentally the newly introduced BC based on the penalization approach seems as remedy. The numerical model consists of strongly coupled partitioned scheme based on the stabilized finite element method.\n\n

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2019-03-28
15:07

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2019-03-28
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2019-03-28
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2019-03-28
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2019-03-28
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2019-03-28
15:07
Comparison of properties and behaviour of selected systems of thin film - Substrate with TiSiN, AlCrN and AlTiN on samples and selected cutting tools
Mertová, Andrea ; Štěpánek, Ivo ; Šimečková, Lucie ; Dudáčková, Simona ; Ulrychová, Monika
The paper is devoted by evaluation of comparison of selected systems of thin film - basic material, which are optimized in the range of solution of the project with goal application of thin films on selected real cutting tools. There are evaluated thin films prepared by low voltage reactive arc evaporation in vacuum with different composition of ternary nitride. The evaluation of properties and behaviour is oriented on systems with thin films TiSiN, AlCrN and AlTiN. The surfaces of these systems of thin film - basic material are evaluated from point of view of verification homogeneity of thin films through of area of samples and through of geometry of selected real tools too. The distribution of thickness is evaluated by x-ray fluorescence analysis on samples and real selected places of geometry of tools too. The other comparison is realised from point of view of differences of mechanical properties and behaviour by using of indentation methods namely of nanoindentation and scratch indentation for evaluation of differences in hardness and adhesive cohesive behaviour of systems thin films - basic material.

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2019-03-28
15:07
Nonparametric density estimates used for multiple AE source detection
Gális, P. ; Chlada, Milan
Paper deals with the localization of acoustic emission (AE) sources by means of exact geodesic curves on 3D vessels composed of several parametrized surfaces. Precise arrival times of AE events, plugged in DeltaT/DeltaL localization is discussed. Two-dimensional nonparametric (kernel) density estimates are employed to obtain the localization maps on 3-D surfaces and the potential regions of cracks are visibly highlighted. This newly proposed procedure is applied to steam reservoir and other experimental vessels. The results presented are accompanied by thoroughgoing evaluation of their quality and practical usefulness.

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2019-03-14
15:59
Jádro havarijního modelu pro městskou zástavbu & Experimenty úniků plynu pro rurální oblast
Chaloupecká, Hana ; Jakubcová, Michala ; Kellnerová, Radka ; Jurčáková, Klára
Zpráva se skládá ze dvou částí. \nPrvní část se zabývá tvorbou jádra havarijního modelu pro krátkodobé úniky plynů pro případ městské zástavby. Je zde vysvětlen postup při tvorbě daného modelu, kde po zadání vstupních údajů o úniku plynu jako výstup získáme hustoty rozdělení pravděpodobnosti pro jednotlivé charakteristiky úniku (např. 99. percentil koncentrací) a jednotlivá zasažená místa. Z výstupu lze mimo jiné vyčíst, jaké jsou nejpravděpodobnější hodnoty charakteristik oblaku, se kterými se při nehodě můžeme setkat, ale i extrémní případy. Toto je největší rozdíl oproti dosud běžně užívaným modelům pro bezpečnostní složky, u nichž jsou jako výstup k dispozici pouze průměrné kontury pro oblaky a koncentrační pole. \nVe druhé části zprávy jsou popsány experimenty úniků plynu pro rurální oblast. Jedná se jak o splnění podobnostních kritérií při modelování v aerodynamickém tunelu, tak o samotné experimenty a tvorbu databáze ze získaných údajů. \n

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