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9432. Study of site effect using mining induced seismic events and ambient noise from Karviná Region
- Creator:
- Zdeněk Kaláb and Lyubushin, Alexey A.
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Geologie. Meteorologie. Klimatologie, geodynamika, geodynamics, mining induced seismic event, ambient noise, spectral ratio, frequency analysis, 7, and 551
- Language:
- English
- Description:
- Evaluation of seismic loading in urban areas is not a simple process. The horizontal to vertical spectral ratio method technique has been often used for determination of site effect recently. Results from the re-interpretation of mining induced seismic events from Karviná region in frequency domain using archival databases will be presented in this study material. Also, spectra of continuous records (a bout two days) and evolution of spectra within a moving time window of the length 10 seconds are presented. These continuous records were registered on two places with different geological conditions., Zdeněk Kaláb and Alexey A. Lyubushin., and Obsahuje bibliografické odkazy
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
9433. Study of the effect of moisture content and bending rate on the fracture toughness of rocks
- Creator:
- Leona Vavro and Kamil Souček
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Geologie. Meteorologie. Klimatologie, geodynamika, geodynamics, fracture toughness, bending rate, tensile strength, 7, and 551
- Language:
- English
- Description:
- Generally, rock material failure is controlled by cracks under specific conditions. The study of rock fracture toughness belongs to the current frequent directions of research in the area of rock failure. The present paper describes the effects of parameters influencing the resultant properties of rock materials (bending rate, rock moisture) during fracture toughness measurement of different kinds of rocks (sandstone, marble, granite). The highest fracture toughness values were found in the marble samples. This is probably due to the inner structure of analysed marble, which is composed of only one mineral (calcite) and also has a lower porosity than the used granite. The lowest fracture toughness values were found in the sandstone sample, and reached c. 17-30 % of the measured fracture toughness values of the analysed granite and marble samples. As in the case of the other mechanical properties of rocks (e.g. uniaxial compressive strength) also in the case of higher sandstone (carboniferous) moisture the fracture toughness values decrease and its deformation ability increases. Preparation of samples for fracture toughness tests and performance of these tests are more complicated than in the case of tensile tests (e.g. the Brazilian test) and therefore this contribution presents a comparison between fracture toughness of analysed rocks and tensile strength values. The measured data in this study considering the fracture toughness tests and Brazilian tests were compared with results published by Zhang (2002)., Leona Vavro and Kamil Souček., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
9434. Study of the robustness of a meta-algorithm for the estimation of parameters in Radial Basis Function Neural Networks design
- Creator:
- Parras-Gutierrez, Elisabet, del Jesus, Jose , Rivals, Victor M., and Merelo , Juan J.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- RBFN, meta-algorithm, evolutionary algorithm, and parameter estimation
- Language:
- English
- Description:
- Radial Basis Function Networks (RBFNs) have shown their capability to be used in classification problems, and therefore many data mining algorithms have been developed to configure RBFNs. These algorithms need to be given a suitable set of parameters for every problem they face, thus methods to automatically search the values of these parameters are required. This paper shows the robustness of a meta-algorithm developed to automatically establish the parameters needed to design RBFNs. Results show that this new method can be effectively used, not only to obtain good models, but also to find a stable set of parameters, available to be used on many different problems.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
9435. Study of thermal behaviour of continuously cast billets
- Creator:
- Klimeš, Lubomír, Štětina, Josef, Parilák, Ľudovít, and Buček, Pavol
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- continuous casting, temperature field, thermal behaviour, and dynamic solidification model
- Language:
- English
- Description:
- In continuous casting the quality of cast steel slabs and billets, thermal stress, surface defects and cracks formation are highly dependent on the temperature distribution along the entire continuously cast blank. The main attention is usually paid to the surface temperatures and particularly to the corner temperature distributions. However, from the technological point of view the temperature distribution in the core of cast blank, which is highly related to the metallurgical length and to the unbending process, is very important as well. Therefore, monitoring of temperature field of cast blanks, its prediction by using numerical models as well as controlling and optimization tasks of secondary cooling strategy are priority issues for technologists, quality engineers, and operators of continuous casting machine. The paper is aimed at the thermal analysis and the investigation of temperature field of cast billets by utilizing the original numerical model of temperature field of continuously cast steel billets. In particular three grades of steel with different carbon content and the 200x200 mm billets, which are cast in Železiarne Podbrezová in Slovakia, are considered. The performed study and presented software tools can be used by engineers to enhance the quality and productivity of continuously cast steel and to improve the competitiveness of steelworks. and Obsahuje seznam literatury
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
9436. Study on effects of electrical stimulation on rabbit esophageal body motility in vivo
- Creator:
- Zhang, L, Wang, B, Jin, H, Zhao, W, and Zhao, C
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- fyziologie člověka, human physiology, Electrical stimulation, Esophagus motility, High-resolution manometry, 14, and 612
- Language:
- English
- Description:
- Electric stimulation (ES) could induce contraction of intestinal smooth muscle. The aim of this study was to analyze the effects of ES on esophageal motility and the underlying mechanism in vivo. Twenty-eight rabbits were equipped with a pair of subserosa electrodes (connected to an electrical stimulator) in the lower segment of the esophagus. The ES signal consisted of bipolar rectangular pulse trains, lasting for 3 s, with different amplitudes (1 mA, 3 mA, 5 mA and 10 mA), and frequencies (10 Hz, 20 Hz and 50 Hz). The amplitude of the contraction was recognized by high-resolution manometry. The effect of ES was tested under anesthesia and following administration of atropine, phentolamine or L-NAME. ES induced esophageal contraction at the stimulated site. A statistically significant increase in esophageal pressure was observed when the stimulation amplitude was above 3 mA. The increase in esophageal pressure was associated with the amplitude of stimulus as well as the frequency. During stimulation, atropine, phentolamine and L-NAME had no effect on the increase of esophageal pressure induced by ES. These findings implied that ES induced esophageal contraction were not mediated via the NANC, adrenergic or cholinergic pathway. The amplitude of esophageal contraction was current and frequency dependent., L. Zhang, W. Zhao, C. Zhao, H. Jin, B. Wang, B. Wang., and Seznam literatury
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
9437. Study on the law mining stress evolution and fault activation under the influence of normal fault
- Creator:
- Wu, Quan-sen, Jiang, Li-shuai, and Wu, Quan-lin
- Format:
- print, bez média, and svazek
- Type:
- article, články, journal articles, model:article, and TEXT
- Subject:
- Geologie. Meteorologie. Klimatologie, horniny, hornictví, rocks, mining, normal fault, mining stress distribution, fault activation, energy evolution, rock burst hazard, 7, and 551
- Language:
- English
- Description:
- Using the FLAC3D numerical simulation method, the characteristics of mining stress evolution, fault activation patterns, and fault energy evolution characteristics are simulated and analyzed in the process of the footwall and hanging wall working face heading to a normal fault. The study shows that the fault cut off the mining stress propagation of overlying strata, and the stress blocking effect due to the fault is evident. When working faces head towards a fault, the abutment pressure and the vertical stress of the surrounding rock increase first and subsequently decrease. The abutment pressure of the coal wall and fault is highest when the distances to the fault are 40 m and 30 m for the footwall and hanging wall working faces, respectively. Moreover, the hanging wall mining stress is higher than the footwall mining stress. Fault activation in high-located strata precedes that in low-located strata when working faces head towards the normal fault. Energy is gradually accumulated before unstable fault events take place because of mining, and fault instability quickly releases a lot of energy. The mining stress concentration and fault activation due to faults easily result in rock bursts and mine seismicity, Wu Quan-sen, Jiang Li-shuai and Wu Quan-lin., and Obsahuje bibliografické odkazy
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
9438. Sub-tegumental ventral fibres surrounding the vaginal opening of Entobdella soleae (van Beneden et Hesse,1864) Johnston, 1929 (Platyhelminthes: Monogenea: Capsalidae)
- Creator:
- Kearn, Graham C.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Language:
- English
- Description:
- The distribution of F-actin in the monogenean Entobdella soleae (van Beneden et Hesse, 1864) Johnston, 1929 (Platyhelminthes: Capsalidae) was revealed by staining paraformaldehyde-fixed specimens with FITC-labelled phalloidin. On the ventral surface on the left side of the body, just posterior to the pharynx, a concentrically arranged array of fluorescent fibres was observed, following a circular path around the tiny ventral opening of the vagina. It is assumed that this asymmetrically placed array of actin fibres is contractile and the possible role of these fibres in the assimilation of sperm from an attached spermatophore into the vagina is discussed.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
9439. Subacute exposure to alcohol in relation to bone microstructure of mice
- Creator:
- Sarocka, A, Kovacova, V, Omelka, R, Bauerova, M, Kapusta, E, Goc, Z, Formicki, G, and Martiniakova, M
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- kosti, myši, bones, mice, alcohol, microstructure, 14, and 612
- Language:
- English
- Description:
- Our study aimed to investigate subacute exposure to alcohol in relation to bone microstructure of mice. Animals from experimental (E) group drank a solution composed of 15 % ethanol and water for 14 days (one remodeling cycle), while those from control (C) group drank only water. In the compact bone of E group, decreased bone formation and increased porosity were observed which corresponds with lower levels of serum alkaline phosphatase and glutathione. Alcohol significantly increased sizes of primary osteon's vascular canals and decreased those of secondary osteons, Haversian canals. Relative bone volume, bone mineral density (BMD), relative bone volume without marrow cavity were also lower in E group. On the contrary, trabecular bone microstructure did not differ significantly between E and C groups. Liver function test showed higher levels of alanine aminotransferase, aspartate aminotransferase in alcohol-fed mice. Serum calcium, phosphate were significantly lower in E group. According to our study, only changes in compact bone microstructure of mice following one remodeling cycle were observed due to both direct and indirect effects of alcohol., A. Sarocka, V. Kovacova, R. Omelka, M. Bauerova, E. Kapusta, Z. Goc, G. Formicki, M. Martiniakova., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
9440. Subalgebra extensions of partial monounary algebras
- Creator:
- Jakubíková-Studenovská, Danica
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- partial monounary algebra, subalgebra, congruence, quotient algebra, subalgebra extension, ideal, and ideal extension
- Language:
- English
- Description:
- For a subalgebra ${\mathcal B}$ of a partial monounary algebra ${\mathcal A}$ we define the quotient partial monounary algebra ${\mathcal A}/{\mathcal B}$. Let ${\mathcal B}$, ${\mathcal C}$ be partial monounary algebras. In this paper we give a construction of all partial monounary algebras ${\mathcal A}$ such that ${\mathcal B}$ is a subalgebra of ${\mathcal A}$ and ${\mathcal C}\cong {\mathcal A}/{\mathcal B}$.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public