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Metodika měření útlumu rychlosti projektilu v balisticky odolném materiálu
Šperl, Martin ; Bejdl, Jan ; Wolf, Benjamin ; Koutný, O. ; Kratochvíl, J. ; Bystrianska, E. ; Křesťan, J. ; Bartošková, M. ; Holešinský, R. ; Drdlová, M. ; Šoukal, F. ; Pěchouček, P.
V práci je vypracována kompletní metodika k měření útlumu rychlosti projektilu v balisticky odolném materiálu vč. popisu potřebných měřících zařízení.
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Combinatorial Properties of Finite Models
Hubička, Jan ; Nešetřil, Jaroslav (vedoucí práce) ; Pultr, Aleš (oponent) ; Cameron, P. (oponent)
V této práci se věnujeme univerzáním strukturám pro vnoření i homomorfismy a sjednocujeme výsledky týkající se obou těchto pojmů. Ukážeme, že mnohé z univerzálních a ultrahomogenních struktur jsou reprezentovatelné pomocí jednoduchých konečných technik. O takových strukturách říkáme, že mají konečnou prezentaci. Na základě klasické reprezentace náhodného grafu (R. Rado) hledáme konečné prezentace pro známé ultrahomogenní struktury. Podle klasifikačního programu najdeme prezentace všech ultrahomogenních neorientovaných grafů, turnajů a částečných uspořádání. Ukážeme také prezentaci racionálního Urysohnova prostoru a některých orientovaných grafů. Věnujeme se také známým strukturám, které lze považovat za konečné prezentace. Uvádíme přehled struktur, které popisují částečná uspořádání a u nichž můžeme dokázat jejich univerzalitu (například uspořádání množin slov, geometrických objektů, polynomů, či homomorfismové uspořádání struktur). Ukážeme nový kombinatorický důkaz existence univerzálních struktur pro třídy struktur definovaných pomocí zakázaných homomorfismů. Z tohoto důkazu plyne nová konstrukce homomorfismových dualit a souvislost s Urysohnovým prostorem.
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Numerical simulation of dynamic loading of a test blade in forced torsional vibration
Šidlof, P. ; Vomáčko, V. ; Lepičovský, Jan ; Šimurda, David ; Štěpán, M. ; Luxa, Martin
Within a new project focused on blade flutter research, building on previous experience with the NASA Transonic Flutter Cascade facility, static blade cascade and airfoil flutter experiments realized in cooperation between the Institute of Thermomechanics and Technical University of Liberec, a new test facility is under development for the investigation of high subsonic and transonic flow in a blade cascade under forced torsional oscillation. Apart from aerodynamic loading of the blades, the oscillating blade will be exposed to significant structural stresses due to the highfrequency torsional vibration. In order to avoid structural integrity issues from high-cycle fatigue, a numerical simulation of the stress and displacement of the blade was realized. Regions where equivalent stress reaches maximum values were identified, and elastic deformations were computed. The limits in oscillation amplitude and frequency for the safe operation of the experimental setup were discussed.
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Corporate profitability and the global persistence of corruption
Ferris, S. P. ; Hanousek, Jan ; Trešl, Jiří
We examine the persistence of corporate corruption for a sample of privately-held firms from 12 Central and Eastern European countries over the period 2001 to 2015. Creating a proxy for corporate corruption based on a firm’s internal inefficiency, we find that corruption enhances a firm’s profitability. A channel analysis further reveals that inflating staff costs is the most common approach by which firms divert funds to finance corruption. We conclude that corruption persists because of its ability to improve a firm’s return on assets, which we refer to as the Corporate Advantage Hypothesis.
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Photocatalytic concrete screeds with self-cleaning and antimicrobial function
Bíbová, Hana ; Šubrt, Jan ; Pližingrová, Eva ; Jakubičková, M. ; Sázavská, T. ; Dohnálek, P. ; Hykrdová, Lenka ; Jirkovský, Jaromír
Photocatalytic concrete screeds with self-cleaning and antimicrobial function have been developed and tested. These building materials contain sand grains with deposited composite TiO2/SiO2 layers. Two types of the screeds, grey and white, were prepared and their photoactivity and material characteristics were compared. Commercial TiO2 photocatalysts from several manufacturers were employed. Effects of different parameters, such as temperature of the coated sand calcination, humidity, and surface abrasion, were followed. Mechanical properties of the screeds were analyzed by SEM/XRD microscopy. Photocatalytic activity was tested by means of NOx oxidation (ISO norm 22197-1/2007). Antibacterial activity was evaluated by modified ISO norm 27447/2009 with Bacillus subtilis as a model organism.
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Závěrečná zpráva 2020 o výzkumu výsypek v okolí Sokolova na základě dohody mezi ENKI ops a Ústavem půdní biologie BC AV ČR
Frouz, Jan ; Bartuška, Martin ; Lišková, K. ; Angst, Gerrit ; Sun, Daquan ; Kučera, J. ; Bednářová, E. ; Spurná, V. ; Jílková, Veronika ; Heděnec, P. ; Ćápová, K. ; Müllerová, V. ; Irshach, S.
Zpráva přináší souhrn výsledků výzkumu obnovy půd a ekosystémů na území postiženém těžbou nerostů na Sokolovsku na základě dohody mezi ENKI ops a Ústavem půdní biologie BC AV ČR za rok 2020.
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Dynamic impact wear and impact resistance of W-B-C coatings
Daniel, Josef ; Grossman, Jan ; Buršíková, V. ; Zábranský, L. ; Souček, P. ; Mirzaei, S. ; Vašina, P.
Coated components used in industry are often exposed to repetitive dynamic impact load. The dynamic impact test is a suitable method for the study of thin protective coatings under such conditions. Aim of this paper is to describe the method of dynamic impact testing and the novel concepts of evaluation of the impact test results, such as the impact resistance and the impact deformation rate. All of the presented results were obtained by testing two W-B-C coatings with different C/W ratio. Different impact test results are discussed with respect to the coatings microstructure, the chemical and phase composition, and the mechanical properties. It is shown that coating adhesion to the HSS substrate played a crucial role in the coatings.
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An experimental investigation of yield surfaces anisotropies
Štefan, Jan ; Parma, Slavomír ; Marek, René ; Plešek, Jiří ; Feigenbaum, H. P. ; Ciocanel, C.
This contribution is dedicated to a rigorous experimental procedure for evaluation of yield surfaces of common metallic materials. This yield surface tracing procedure employs thin-walled tubular specimens to identify individual yield points of the material under arbitrary combinations of axial load and torque. A yield point is identified on the basis of a prescribed threshold for the effective plastic strain that is being continuously and fully automatically evaluated throughout the test. The experimental results generated with this tracing method are promising, leading to shapes of the yield surfaces conform with the von Mises criterion. The proposed methodology can effectively capture the YS shape.
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Intra-industry transfer of information inferred from trading volume
Brushko, Iuliia ; Ferris, S. P. ; Hanousek, Jan ; Trešl, Jiří
This study examines the responsiveness of trading volume to a firm’s earnings announcements. We find that the volume and earnings surprise information generated at the first earnings announcement within an industry help to explain the stock returns of the non-announcing firm. Specifically, it explains their equity performance at the time of the first industry announcement and then again after their own earnings announcement. These results provide novel insights into how earnings announcements contain both firm specific as well as industry information that is value relevant for investors.
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