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Methodology of the measuring of projectile velocity degradation in the ballistic resistant materials
Šperl, Martin ; Bejdl, Jan ; Wolf, Benjamin ; Koutný, O. ; Kratochvíl, J. ; Bystrianska, E. ; Křesťan, J. ; Bartošková, M. ; Holešinský, R. ; Drdlová, M. ; Šoukal, F. ; Pěchouček, P.
The methodology report describe a complete methodology for measuring the decrease of projectile speed in ballistic resistant material, incl. description of the required measuring systems.
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Combinatorial Properties of Finite Models
Hubička, Jan ; Nešetřil, Jaroslav (advisor) ; Pultr, Aleš (referee) ; Cameron, P. (referee)
We study countable embedding-universal and homomorphism-universal structures and unify results related to both of these notions. We show that many universal and ultrahomogeneous structures allow a concise description (called here a finite presentation). Extending classical work of Rado (for the random graph), we find a finite presentation for each of the following classes: homogeneous undirected graphs, homogeneous tournaments and homogeneous partially ordered sets. We also give a finite presentation of the rational Urysohn metric space and some homogeneous directed graphs. We survey well known structures that are finitely presented. We focus on structures endowed with natural partial orders and prove their universality. These partial orders include partial orders on sets of words, partial orders formed by geometric objects, grammars, polynomials and homomorphism orders for various combinatorial objects. We give a new combinatorial proof of the existence of embedding-universal objects for homomorphism-defined classes of structures. This relates countable embedding-universal structures to homomorphism dualities (finite homomorphism-universal structures) and Urysohn metric spaces. Our explicit construction also allows us to show several properties of these structures.
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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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Final report about research in Sokolov post mining sites in 2020 based on agreement between ENKI ops and Institute of Soil Biology BC CAS
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.
The report brings main results of the research about soil and ecosystem recovery in post mining landscape near Sokolov based on agreement between ENKI ops and Institute of soil biology, BC CAS.
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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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