The orientation of the Earth in space is measured by space geodetic techniques. Each technique has its weaknesses so the best way how to get a representative solution of Earth orientation parameters is to combine all of them together using some appropriate method. There are basically two approaches, the rigorous and non-rigorous one. The method used in this paper belongs to the second category. Since 1999, when the authors Kostelecký and Pešek put basis of the combination method, the method has been modified and improved. The particular improvements are described hereafter and recent results are presented. These results of collocation station velocities are compared with the velocities published by ITRF 2005 and NUVEL-1A. The mean values of differences are 2.7 mm/y and 5.9 mm/y, respectively., Vojtěch Štefka, Ivan Pešek, Jan Vondrák and Jan Kostelecký., and Obsahuje bibliografii
Recently we derived a new star catalog EOC-4 that contains not only the mean positions and linear proper motions, but also periodic changes, due to orbital motions, for double and multiple star systems. The catalog contains 4418 stars that were observed in programs monitoring Earth orientation by optical astrometry during the 20th century. 599 stars of the catalog have significant periodic components. This catalog is now used, as a basic celestial frame, to obtain the Earth orientation parameters from optical astrometric observations of latitude/universal time/altitude in the interval 1899.7-1992.0. Polar motion is determined in 5-day steps for the whole interval studied, Universal time covers the interval 1956.0-1992.0 (i.e., after the invention of atomic clocks) also in 5-day steps, and celestial pole offsets (with respect to recent IAU2000 and IAU2006 models of nutation and precession) are modeled by second-order polynomials of time. In addition to these, a combination of Love and Shida numbers for each observing site is computed., Jan Vondrák, Cyril Ron and Vojtěch Štefka., and Obsahuje bibliografii
The use of rock physics modeling and petrophysical analysis has become an integral part of quantitative seismic interpretation. In the present study, the above-mentioned techniques are applied to the reservoir interval of Basal Sand of Cretaceous age widely distributed in the Lower Indus Basin of Pakistan. The data used for this purpose consists of complete suits of wireline logs from four well A, B, C and D. The primary goal of this work is to understand the trends of seismic parameters such as P-wave velocity (VP), S-wave velocity (VS), bulk modulus, bulk density as a function of fluid saturation and porosity in this sand interval. Petrophysical analysis based on well logs is used to obtain petrophysical properties such as porosity, the volume of shale, fluid saturation, P-wave velocity (VP), S-wave velocity (VS) and density at reservoir conditions. The results show that seismic parameters are very sensitive to fluid saturation, fluid types and rock-forming sediments. Reservoir porosity and fluid saturation control the elastic response of Basal Sand due to which seismic velocities decrease with an increase in porosity and fluid saturation., Perveiz Khalid, Muhammad Arshad, Muhammad Irfan Ehsan, Aziz Ahmad and Shehzad Khurrum., and Obsahuje bibliografii
A good knowledge of hydraulic characteristics, particularly the retention curves, of the applied materials is necessary when studying the efficiency of a capillary barrier or numerically simulating flow of water in its layers. The main difficulties of their measurements originate in the fact that the coarse-grained soils of capillary barriers come from the state of residual moisture to the state of saturation within relatively small interval of pressure head. Hence, it is necessary to carry out the measurements in very fine steps of pressure head. Four materials of two capillary barriers are investigated in this paper. The tension apparatus according to Havlíček and Myslivec was used to measure their retention curves. Both branches of retention curves were measured in order to obtain data suitable for taking hysteresis into account. The method is described and the results are presented. Subsequently, the hydraulic characteristics of the materials are determined and their impact to the capillary barriers efficiency is investigated. The barriers were compared from the viewpoint of their efficiency using the measured data and tipping trough measurements made elsewhere. Explanation of the found differences was suggested and the effect of hysteresis was discussed., Dagmar Trpkošová and Jiří Mls., and Obsahuje bibliografii
We study the efficiency of individual stations of the CRL seismic network in recording the seismic activity in the western Gulf of Corinth, Greece. The stations are located on both the northern and southern coast of the Gulf. The study is based on 5027 earthquakes recorded in 2001, separated into three groups, the southern, central and the northern one. The events were located using the HYPO71PC algorithm. It is shown that the stations significantly differ in their monitoring ability., Jaromír Janský, Jiří Zahradník and Vladimír Plicka., and Obsahuje bibliografii
This paper represents the Romanian contribution in the frame of the European Co-operation "COST ACTION 625" and it is centered on an electromagnetic methodology for the natural hazard assessment due to both the seismic events and associated active faults which are considered to be sources of the most significant landslides in the Subcarpathian area (Romania). This methodology was established according to the geotectonic features of the seismic-active Vrancea zone and Provita de Sus landslide area. Subsequently, a specific approach regarding the electromagnetic precursory parameters, selected according to the temporal invariability criterion for a 2D geoelectric structure in non-seismic condition, taking into consideration their daily mean distribution versus intermediate depth seismic events recorded simultaneously, was elaborated. A similar electromagnetic technique conveying to additional parameters and models concerning the evolution in time of the landslide phenomena was also imposed, so that a disaster forecasting become possible., Dumitru Stanica and Maria Stanica., and Obsahuje bibliografii
The evolution of soil cover in the area of Litovel has been determined on the basis of grain-size distribution, mineralogy of clay fraction, chemical and micromorphological analyses. The object of the present study was a chronosequence of soils in Pleistocene sediments. Paleopedological data indicate that the area underwent environmental changes including several cycles of pedogenesis. This area provides evidence of at least two first-order warm periods. The highest degree of polygenesis can be demonstrated by Braunlehm-like Parabraunerde (PK V - Late Holstein Interglacial) and Chernozem which evolved from Haplic Luvisols (PK IV - warm period within the Riss glacial). The upper part of the profile documents different types of pedosediments which indicate erosion processes., Anna Žigová and Martin Šťastný., and Obsahuje bibliografické odkazy
The GNSS (Global Navigation Satellite System) coordinates time series are still used as a source for determining the velocities of GNSS permanent stations. These coordinates, apart from the geodynamical signals, also contain an interference signal. This paper shows the results of the comparative analysis of the GNSS coordinates time series with a deformation of the Earth's crust obtained from loading models. In the analysis, coordinates time series are used (CODE Repro2013) without loading models (Atmospheric Pressure Loading, Hydrology, Non-Tidal Ocean Loading) at the stage of the reprocessing of GNSS archival data. The analyses showed that in the case of the Up component there is a high correlation between the GNSS coordinates changes and deformations of the Earth's crust from the loading models (coefficient 0.5-0.8). Additionally, we noticed that for horizontal components (North, East) changes occur in the phase shift between coordinates, and the Earth’s crust deformations signals are accelerated or delayed each other (-150 to 200 days). This article shows new methods of iLSE (iteration Least Square Estimation) to determine periodic signals in the time series. Additionally, we compared the values of estimated amplitudes for GNSS and deformation time series. and Kaczmarek Adrian, Kontny Bernard.
This paper contains the studies of the noise level in GPS (Global Positioning System) time series. As the data for this research the authors used changes of the geodetic coordinates of the ASG-EUPOS and associated (Slovak and Czech) sites. The method of precise GPS observations processing in short-time intervals was worked out in the Centre of Applied Geomatics, Military University of Technology. The authors focus on the diurnal and sub-diurnal frequency bands (tidal) as the tidal effects influence the sites’ positions at the most and the model used in the standard processing software does not contain geodetic coefficients. Thus the residual values of the geodetic coordinates time series should hold some information in the shape of coloured noise. The paper comprise short description of the Earth tides phenomenon, the concept of the tidal parameters determination, character of the white and coloured noise and the assessment of the noise estimation from GPS data. As the processed network contains 130 sites the spatial distribution of the noise’s parameters is also investigated., Janusz Bogusz and Bernard Kontny., and Obsahuje bibliografii