CSÁKI, Štefan: Thermophysical and electrical properties of illite-based ceramics. [Doctoral thesis]. Constantine the Philosopher University in Nitra. Faculty of Natural Sciences. Charles University. Faculty of Mathematics and Physics. Supervisor: prof. RNDr. Libor Vozár, CSc. (Constantine the Philosopher University in Nitra), doc. Ing. Patrik Dobroň, PhD. (Charles University). Nitra & Prague, 2018. 107 p. Illitic clays are of special importance in the ceramic industry. Therefore, a deep knowledge of the thermophysical processes, as well as the electric properties, is of special importance. The illitic clay originated in Northeastern Hungary was used in this thesis. The reactions, occurring during firing, were studied using thermal analyses (Differential thermal analysis, Thermogravimetry, Thermodilatometry) and special attention was paid to the measurement of the electrical conductivity (both DC and AC). Up to 250 řC, where the removal of the physically bond water (PBW) takes place, the dominant charge carriers were the H+ and OH- ions. After the PBW was removed, Na+ and K+ ions became the dominant charge carriers. During dehydroxylation (450 - 750 řC) H+ and OH- ions were freed from the illite structure, which supported the electrical conduction in the samples. At ~ 970 řC glassy phase appeared...

The diploma thesis deals with calibration of AE sensors used in diagnostics of bearings. Two different conceptual solutions similar to those used in the diagnostics of bearings were designed in the design. Subsequently, the experimental device was designed for relative calibration using the rotation of bearings as a continuous AE source. The experimental part is oriented to the observation of the RMS parameter, which serves as a sensor sensitivity evaluation parameter. As sources of AE, bearings with a certain type of damage were used, which allowed for the formation of sensitivity characteristics according to the type of damage. Sensitivity characteristics of selected AE sensors have been developed to determine the effectiveness in relative calibration. The exponential sensitivity sensitivity of the MDK-13 sensors was observed on the software amplification of the AE analyzer. A proposal for the calibration method for MDK-13 type sensors was developed on the principle of comparison with the reference sensor.

The goal of the present work is investigation of deformation mechanisms in magnesium-based metal matrix composites and examination of the influence of morphology of strengthening phase on the mechanical properties. The microstructure of the specimen was studied by means of light optical and electron microscopy (SEM). Compression tests in the temperature range of 20řC-300řC were preformed. Acoustic emission measurements were performed during compression test at room temperature, whose help us elucidate the ongoing micromechanisms during the straining. Furthermore residual stress in the magnesium matrix at different strain levels was measured by neutron diffraction.

When companies go public, the shares they sell tend to be underpriced, and thus exhibit a significant price jump on the first day of trading. As a result, IPO investors materialize significant first-day returns. In the long-run, however, relative to some benchmark, investors appear to lose out by continuing to hold the stocks of firms that have recently gone public. These IPO phenomena are subject of the following study. The thesis addresses two main objectives. First, it systematically surveys relevant empirical evidence and theories that have been proposed to explain IPO underpricing and long-run underperformance. In addition, both anomalies are studied form the viewpoints of two competing finance theories: efficient market hypothesis and behavioral finance. Theories of underpricing are grouped within two broad categories: asymmetric information based models and behavioral theories. While asymmetric information based models assume that one of the IPO transaction parties knows more than others, and that these information frictions give rise to underpricing, behavioral explanations, on the other hand, assume the presence of irrational investors who are the prime cause of underpricing. Theories of poor long-term performance are based on behavioral finance perspective only, where "investor sentiment" plays the main role. On the contrary, proponents of market efficiency strongly argue that the notion of systematic IPOs long-run underperformance is spurious. Secondly, the thesis empirically examines the presence of underpricing and the long-performance of IPOs in European NYSE Euronext markets. In general, the results undoubtedly show that IPOs in the sample are moderately underpriced on average. However, the assessment of IPOs long-run performance provides contentious findings and probably requires further research.

This paper discusses the possible use of Hilbert-Huang transform to analyze the data obtained from physical experiments. Specifically for the analysis of acoustic emission in the form of acoustic shock. The introductory section explains the concept of acoustic emission and its detection process. Subsequently are discussed methods for signal analysis in time-frequency domain. Specifically, short-term Fourier transform, Wavelet transform, Hilbert transform and Hilbert-Huang transform. The final part contains the proposed method for measuring the performance and accuracy of different approaches.