The aim of this study was to assess the performance of several approximation techniques for ionospheric total electron content (TEC) mapping. Approximation techniques based on data-fitting with local or general two-dimensional polynomials, local planes or distance-dependent interpolation were applied and tested. For the ionosphere modeling, dual-frequency GPS data from Polish GBAS system (ASG-EUPOS) were used, and TEC was estimated together with hardware delays from phasesmoothed pseudoranges. Next, grids of vertical TEC values with spatial resolution of 0.25 degrees in both latitude and longitude were generated using the evaluated approximation techniques. Subsequently the grids were used to create regional TEC maps with 5-minute temporal resolution, and also to create ionospheric delay corrections for GPS positioning. The quality of the resulting ionospheric maps was tested twofold, firstly by comparison to high-quality CODE global ionosphere maps (GIM), which were generated using data from about 150 GPS sites of the International GNSS Service (IGS). Secondly, by creating double-differenced ionospheric delay corrections and comparing them to reference values derived from the reference network data processing. For the correction tests, two perpendicular baselines directed North-South (N-S) and West-East (W-E) and reaching up to 100 km were selected. The approximation methods were analyzed with a special emphasis on the diverse ionospheric conditions. For the testing, a quiet ionosphere day of 20 March 2012 and an active ionosphere day of 9 March 2012 were selected. The results show that the regional models properly represent the changing ionosphere, with the best results provided by data-fitting into local functions., Anna Krypiak-Gregorczyk, Pawel Wielgosz, Dariusz Gosciewski and Jacek Paziewski., and Obsahuje bibliografii
Vermiculite in its macroscopic form occurs in the Archaean supracrustal rocks exposed towards east of Sargur supracrustal complex in Karnataka state. The present study forms the first detailed work on the occurrence of vermiculite associated with the ultramafic rocks in the Agasthyapura, which lies in the long. 76° 50’ 658” and lat. 12° 15’ 976”. Petrography, X-ray diffraction, FTIR, DTA&TGA, SEM, fluid inclusion and electron probe analyses are presented in this contribution study. The probable origin of vermiculite from biotite through hydrobiotite is discussed., Kikkeri N. Prakash Narasimha, Honnaiah Ramalingaiah, Karel Melka, K. Krishnaveni, Pinnelli S. R. Prasad, Chikkamadaiah Krishnaiah, Katihalli S. Jayappa and Atni V. Ganesha., and Obsahuje bibliografické odkazy
In presented work natural expanded vermiculite was used as a starting material for synthesis of Fe-doped catalysts. Material was modified with increasing amount of Fe by ion-exchange and precipitation of iron oxide. Composite materials were characterized with respect to their structure (X-ray diffraction, Infrared spectra using Diffuse Reflectance), agglomeration state of Fe (Ultraviolet-Visible spectra using Diffuse Reflectance) and chemical composition. Activity in H2O2 decomposition as well as in phenol oxidation was studied in liquid phase at atmospheric pressure and temperature up to 70 °C. It was shown that doping with Fe increases catalytic activity. However, excess of iron resulted in formation of undesired side-products., Agnieszka Węgrzyn, Lucjan Chmielarz, Paweł Zjeżdżalka, Magdalena Jabłońska, Andrzej Kowalczyk, Agata Żelazny, Manuel Vázquez Sulleiro and Marek Michalik., and Obsahuje bibliografii
The West Bohemia earthquake swarm foci are approximated by a circular seismic source model, which radius is assumed to depend only on magnitude of the event. We consider two different models of average slip (i) a constant slip and (ii) a slip exponentially scaled to the magnitude of the event. Based on these assumptions, we stacked the contributions of individual events into representative final fault slip. We processed in such a way four significant swarms recorded during the last three decades in 1986, 1997, 2000 and 2008. Constant slip model indicates final slip was composed of 2 or 3 principal asperities located on one or two different planes. On the contrary, scaled slip model indicates that one big asperity prevails. It is not possible yet to select the preferred slip model. Analysis of the temporal activity of all swarms generally shows three principal phases: starting phase, main phase and fading phase; the upwards trend of activity spreading was observed (slip animation is presented in www supplement http://www.ig.cas.cz/kolar/StopPhase/Asperity). The maximal possible cumulative slip value may have reached the order of meters., Petr Kolář, Bohuslav Růžek, Alena Boušková and Josef Horálek., and Obsahuje bibliografii
The purpose of this work was to detect groundwater pollution and to identify the conditions of soil and groundwater near the coal waste disposal "Panewniki" Halemba-Wirek Coal Mine using geoelectrical measurements. The firs t applied method was the VLF (Very Low Frequency) technique. This method, using military signals, allowed to perform the in-phase and the quadrature maps. Data were collected from four study areas located near the coal waste dump. Observed anomalies on both maps for each area showed places with different conductivity al lowed to detect the contaminated and uncontaminated zones. The VLF survey indicated that the contamination occurs in the eastern part of study area and is characterized by positive values of both measured electrical fields (the in-phase and the quadrature components). After preliminary contaminated zones were recognized using VLF met hod, an electrical imaging meth od was applied. Two electrical imaging profiles were carried out near the waste dump. The measurements a llowed to create the geoele ctrical model of surrounding area and to investigate the leachate plume. The electrical imaging showed that the greatest pollution occur in the area immediately adjacent to the coal waste what is confirmed by VL F survey. Based on the geological and ge ophysical knowledge from archives and on present researches, the contaminated aquifer with electrical resistivity of 5 to 15 Ω m deposited at depths of 3 to 7 m was found., Arlena Kowalska, Marta Kondracka and Maciej Jan Mendecki., and Obsahuje bibliografické odkazy
This paper presents the results of the application of wavelet decomposition to processing data from the GGP sites (The Global Geodynamics Project). The GGP is an international project within which the Earth's gravity field changes are recorded with high accuracy at a number of stations worldwide using superconducting gravimeters. Data with a 5-second sampling interval from Wettzell and Bad Homburg were used for the research. The wavelet transform enables the investigation of the temporal changes of the oscillation amplitudes or the decomposition of the time series for the analysis of the required frequencies. The wavelet decomposition was performed using the regular orthogonal symmetric Meyer wavelet. The research concerned data from an earthquake period recorded at various locations and a quiet period when the gravimeters worked without any disturbances. The decomposition was followed by the Fast Fourier Transform for signal frequency components and then by correlation analyses of corresponding frequency components (for periods from 10 to 60 000 seconds) for all sensor combinations, for the quiet and the earthquake periods separately. Frequency components defining long term changes for all sensor combinations, as well as combinations between two sensors at the same site for the quiet days are characterised by high correlation coefficients. For the time of the earthquake, the Wettzell site data proved strong correlation for all frequency components, while the Bad Homburg site data showed an unexpected decrease of correlation for the majority of frequency components. The authors also showed that wavelet decomposition can be a good method of data interpolation, especially from the time of earthquakes. Moreover, it is a very useful tool for filtering the data and removing the noises., Janusz Bogusz, Anna Klos and Wieslaw Kosek., and Obsahuje bibliografii
Karst landforms can result from a single stage process in which chemical dissolution and mechanical erosion proceed simultaneously or from a two stage process in which chemical dissolution precedes mechanical erosion. During the second of these processes, chemical dissolution leads to the creation of karst features hosting a residual weathering product, here referred to as alterite. An example of one such feature is the enclosed mass of altered rock at Červený Quarry near Klukovice which represents one of the richest localities for exceptionally preserved echinoderm ossicles in the Prague Synform. In this study the processes responsible for the formation of this feature have been investigated. Nineteen samples were obtained from the bioclastic Slivenec Limestone and from these it has been possible to calculate the carbonate volume content, which defines the weathering intensity, and the carbonate rock weathering index, which defines the weathering state. The results demonstrate that carbonate dissolution has not been accompanied by gravitational compaction or the incorporation of mineral inputs. Thin sections analysed under polarised light and under cathodoluminescence emphasise heterogeneous dolomitisation of the limestone. As the weathering grade intensifies, empty rhomboidal pores become increasingly common until, ultimately, the rhomboidal forms are lost due to corrosion and enlargement. In contrast it is rare to find evidence of calcite dissolution and, therefore, the altered mass still hosts almost all of its post dolomitisation micrite, sparite, and bioclasts. Negligible calcite dissolution helps to explain the exceptional nature of the fossil preservation at the site while the dolomite dissolution accounts for the ease with which it is possible to extract the fossils. Further research should focus on better understanding the role of dolomite dissolution in the formation of other important palaeontological localities in the Prague Synform., Matt Rowberry, Caroline Dubois, Olivier Kaufmann, Jean-Marc Baele and Jan Blahůt., and Obsahuje bibliografii
Empirical Mode Decomposition (EMD) is suitable to process the nonlinear and non-stationary time series for filtering noise out to extract the signals. The formal errors are provided along with Global Navigation Satellite System (GNSS) position time series, however, not being considered by the traditional EMD. In this contribution, we proposed a modified approach that called weighted Empirical Mode Decomposition (weighted EMD) to extract signals from GNSS position time series, by constructing the weight factors based on the formal errors. The position time series over the period from 2011 to 2018 of six permanent stations (SCBZ, SCJU, SCMN, HLFY, FJPT, SNXY) were analyzed by weighted EMD, as well as the traditional EMD. The results show that weighted EMD can extract more signals than traditional EMD from original GNSS position time series. Additionally, the fitting errors were reduced 14.52 %, 12.25 % and 8.06 % for North, East and Up components for weighted EMD relative to traditional EMD, respectively. Moreover, 100 simulations of four stations are further carried out to validate the performances of weighted EMD and traditional EMD. The mean Root Mean Squared Errors (RMSEs) are reduced from traditional EMD to weighted EMD with the reductions of 9.08 %, 9.63 % and 6.84 % for East, North and Up components, respectively, which highlights the necessity of considering the formal errors. Therefore, it reasonable to conclude that weighted EMD can extract the signals more than traditional EMD, which can be suggested to analyze GNSS position time series with formal errors., Xiaomeng Qiu, Fengwei Wang, Yunqi Zhou and Shijian Zhou., and Obsahuje bibliografii