This paper pursues the effect of changes in distance and vibration frequency on the vibration velocity amplitude. As an example, we used the vibrating sheet piles at the cons truction of a new multi-functional FEI building on the premises of VŠB - TU Ostrava, at 17 listopadu street. The effect of these changes is monitored both in in-situ measurements and in a simulated real-life situation. The calculation software Plaxis 2D is used for creation of numer ical models. At the close, the results from in-situ measurements are confronted with those achieved from the models., Tomáš Petřík, Eva Hrubešová and Markéta Lednická., and Obsahuje bibliografické odkazy
The absolute gravity measurements are an important tool for reliable monitoring geodynamic phenomena. Based on the experience with the absolute gravimeter FG5#215 (gravimeter of the Center for Earth Dynamics Research), the accuracy of FG5 absolute gravimeters is presented in this study. The instrumental reproducibility of this meter is characterized by the value of 0.7 μGal. Discussed are important environmental effects on gravity measurements, such as atmospheric and hydrological effects, understanding of which is necessary for correct and reliable interpretation of the repeated absolute gravity measurements in geodynamics., Vojtech Pálinkáš, Jakub Kostelecký and Jaroslav Šimek., and Obsahuje bibliografii
In Czech and Polish underground hard coal mines of the Upper Silesian Coal Basin high-energy seismic phenomena are periodically recorded, the sources of which are located ahead of the longwall. Generally, these types of tremors are rooted in very strong, thick layers of sandstone, which are subject to the deformation border. The consequences are discontinuities and cracks with a range depending on the mechanical properties of destroyed rocks: the mechanical parameters of layers. Forecasting methods, developed in the Central Mining Institute, for stress concentration, seismic energy, fault zone and range, together with methods of rock fracturing using liquid or explosives, ,allow precise identification of suitable locations for controlled fracturing of rock mass with a pre-established direction. The size and range of discontinuities have an impact on mining parameters, dependent on basic exploitation intensity and expressed by the average daily progress of the longwall face. The rockmass is locally weakened because of exploitation or technical measures of discontinuities in the roof-rock on the longwall face. To prevent rockburst, measures are needed to reduce the amount of energy accumulating in the rockmass in the area of the longwall face. Knowledge of where stress is concentrated is extremely important for the development and implementation of effective preventative methods. For many years several research centres have been working on defining the range of these areas. In this paper, basic information is presented on methods developed by Central Mining Institute and used in Polish hard coal mines for forecasting energy concentration and assessing how it can be reduced., Jan Drzewiecki and Janusz Makówka., and Obsahuje bibliografii
Estimating the pre- failure points for rocks during laboratory testing is not a trivial task. In this study, a new approach is introduced that utilizes change in the slope of the load-deformation curves of rock in the loading cycle for marking the onset of failure point during uniaxial test of a given rock. At each step, load-deformation data footprints of the rock under test are inspected and a decision is made whether the failure has started or not. The load-deformation data obtained from different tests of different rocks are examined including; Norite, Granite, Limestone, Sandstone, Siltstone and Marble. The computational results over 154 cored rock samples show that the proposed approach locates the onset of failure point for a given rock with an acceptable degree of accuracy., Deniz Mamurekli., and Obsahuje bibliografii
A quantitatively new analog-to-digital converter (ADC) module has been developed during 2010, in co-operation with Tedia Ltd. The module has a 28-bit final resolution and uses 32-bit arithmetic. There are two versions, with four and twelve analog inputs. The 4-input module replaces the original 21-bit version, produced until 2009. The 12-input module is intended to be deployed in small-aperture seismic arrays. The whole set consists of four 3-channel detached modules that can be interconnected with the main module using a cable of up to 100 m in length. This design increases signal-to-noise ratio (SNR) by placing the A/D part as close to the seismograph as possible in order to transmit digital data for storage. All channels are sampled coherently so that all four sensors are automatically synchronised. It allows the detection of local events even though the sync-signal is absent. In other words, the 12-input module is suitable for ad-hoc field measurements even in places where there is no GPS signal. All arrays operated by the Institute of Rock Structure and Mechanics (IRSM) are going to be upgraded to use these modules and some new sites will also be set-up with this innovative equipment (e.g. Lazy in Western Bohemia and Dobrá Voda in Slovakia)., Milan Brož and Jaroslav Štrunc., and Obsahuje bibliografii
The presented technological procedure makes it possible to assemble large magnetic blocks from permanent magnets with a high value of maximum energy product in such a way that the individual magnets or magnetic plates are moved toward each other at a controlled speed in the direction perpendicular to the future common contact surface of these magnets, i.e. parallel to the induction lines crossing this contact surface. Unlike in the previously used way of assembling the blocks, it is thus possible to eliminate the influence of partial demagnetization as the blocks are being assembled and consequently to reach higher values of magnetic induction in the air gap of the magnetic circuit. When applying the new method of assembling the blocks for instance in circuits of magnetic filters for the purification of ceramic suspensions, a prerequisite for the further improvement of the technological parameters of filtration is thus created., Václav Žežulka and Pavel Straka., and Obsahuje bibliografické odkazy
Analyzing the earthquake catalogue of the Upper Egypt area since 1982 revealed some char acteristics of the seismic activity in the area. Construction of a seismicity map according to the seismicity level in the Upper Egypt showed 14 seismic zones and that the seismic activity is intense around the stra it of the Gulf of Suez, along the Red Sea axis, Abu Dabbab and Aswan area. While the detailed study of Aswan zone showed 8 distinct sub-seismic zones and that the activity is concentrated in and around Gable Marawa area. The b-value was calculated for each seismic zone; it is found that the highest value is in Abu Dabbab area followed by Aswan area. A seismic energy rele ased map of the Upper Egypt was constructed for the period from 1982 to 2006; the map reveals the main active zones with high energy values. The study gives new insight for a better understanding of the seismic activity in the Upper Egypt and helps in the seismic hazard assessment., Haggag Hamed Mohamed, Gaber Hassan Hassib, Sayed Abdalah Dahy and Ezzat Mohamed El-Amin., and Obsahuje bibliografické odkazy
The classification scheme for micaceous minerals is described. According to the size of mineral particles micas are divided into macrocrystalline compounds and microcrystalline clay micas. Macroc rystalline micas are differentiated into (a) Mg-Fe-Al micas, (b) Li-micas, (c) micas with other cations. Vertical boundary in the suggested scheme divides micas into trioctahedral and dioctahedral members. Additional subdivision is carried out on the basis of the extent of Si substitution in tetrahedral positions of their crystal lattice. Microcrystalline (<4μm) micas are subordinate to the crystallochemical scheme for macrocrystalline micas. List of mica species together with their varieties and synonyms is in Table 2., Karel Melka., and Obsahuje bibliografické odkazy
Precise relative gravimeters achieve the internal precision about a few μGal 1, even in field conditions. Nevertheless this precision is in fact concerned with the instant of measurement and can not be confused with the accuracy of the gravity at the gravity station, which is influenced by other effects. The best approach of these two values is question of high-quality elimination of instrumental errors and time-variable disturbing effects affecting the relative gravity measurements., Martin Lederer., and Obsahuje bibliografii