This research evaluates the potential benefits of the tightly combined processing of a global navigation satellite system together with the additional ranging observations from a satellite based augmentation system. In specific, the experiment presents performance of precise instantaneous single-frequency positioning based on European Galileo and EGNOS navigation systems. Due to currently low number of Galileo satellites, the test observational data were obtained with hardware GNSS signal simulator. All calculations were performed with in-house developed software - GINPOS. The results show that it is possible to obtain improvement in the accuracy and reliability of single-frequency precise positioning when including observations from SBAS systems. However, one must take in to account that at middle latitudes EGNOS satellites are observed at low elevations what results in higher atmospheric errors affecting its signals., Jacek Paziewski, Paweł Wielgosz and Marta Krukowksa., and Obsahuje bibliografické odkazy
Oil derivatives contamination of soils effects in changes of many physical properties of soil su ch as: electrical resistivity, conductivity and self potential (SP) as well. Thus the measurable a nomalies of these properties are possible to detect with geoelectrical measurements. SP geoelectrical measurements were carried out in the area of controlled oil spill. The oil was spilled into vadose zone of dry sands. The first underground water level was observed at the depth of 10 m. The measurements were carried out along 20 m long profile situated above 3 m long contaminated zone. The part of contaminated zone (1.5 m) had been subjected to bioremediation process with yeasts Yarrowia lipolytica since 4 months. In the border of contaminated zone and biodegradate done chemical gradient was developed and significant in crease of self potentials values can be observed. The measurements were carried out with potential gradient method. L und Imaging System equipment and non-polarizable electrodes (Cu/CuSO 4 ) were applied. Above contaminated and biodegraded zone distinct SP anomaly (10-20 mV) was measured. The anomaly correlates with results of EM, resistivity imaging and induced polarization investigations., Bogdan Żogała, Maciej J. Mendecki, Wacław M. Zuberek and Małgorzata Robak., and Obsahuje bibliografické odkazy
The paper presents the results of research related to the application of GNSS solutions in short observational periods in geodynamical investigations. Authors used the 3-hour solution appointed from hour-long interval of about 30 chosen stations on mountainous terrains from over 100 which were worked out. The main aim was to check the correctness of such solutions by the comparison with the daily ones. Some outliers in East component could testify, that tropospheric or ionospheric models used in the data adjustment are not sufficient for so short-time solutions. The second principal problem, which was considered in the present work is the ability to detect diurnal and sub-diurnal oscillations in changes of permanent stations’ coordinates. Results show unambiguously, that such oscillations appear in all analysed stations. In the paper there are examples of stations with dominant oscillations in different frequencies. The clear homogeneous in the frequencies was not found among any group of stations. It is therefore difficult to affirm, if their origin comes purely from the geodynamical phenomena., Andrzej Araszkiewicz, Janusz Bogusz, Mariusz Figurski and Karolina Szafranek., and Obsahuje bibliografii
The use of Continuously Operating Reference Stations, both singly and as part of an active network, is widely employed in surveying, engineering and other geomatics applications, achieving high accuracy positioning even in real time. With an active network the measurements of the reference stations are processed jointly in order to model the errors and compute network RTK corrections. Due to distance dependent errors (ionospheric and tropospheric delays), single base RTK positioning accuracy decreases with increased baseline length. However, the network solution (NRTK) retains the accuracy and the time to fix ambiguities (TTFA) at a constant level. This study aims to contribute to the scientific research on real time positioning based on active networks. In Southern Spain, ERGNSS, a national CORS network that provides GNSS data for post-processing and real time single- b ased reference station corrections, shares territory with the Andalusian Positioning Network (RAP), a local active network. RAP provides network an d single-based RTK corrections. In order to analyze the quality of real time positioning based on both networks, several tests have been performed on a sample of test points. The reference frame, the time to fix ambiguity resolution, precision, accuracy and repeatability of RTK positioning are considered as the evaluation parameters. The results confirm that the RAP network complements the precise positioning services provided by the ERGNSS network, ensuring accurate real time positioning, full cove rage and reliable positioning services in the Andalusian Community., Mª Selmira Garrido, Antonio J. Gil and Rafael Gaitán., and Obsahuje bibliografické odkazy
Artefacts in applications of the global gravity field and topographic models based on satellite and terrestrial data of diverse kinds are studied. Various types of artefacts are presented and analysed with the aim to understand how the artefacts originated, how to reduce them (if feasible) and to avoid misinterpretations in geoscience. We work with the gravity aspects (gravity anomalies, the Marussi tensor of the second derivatives of disturbing potential, gravity invariants and their specific ratio, strike angles, and virtual deformations), and with surface or bedrock topography. Examples for the Earth, the Moon, and Mars are presented., Jaroslav Klokočník, Jan Kostelecký, Aleš Bezděk and Gunther Kleteschka., and Obsahuje bibliografii
Samples of bottom ash and fly ash coming from the combustion of lignite with the addition of limestone, from the cocombustion of lignite and wood residue with limestone and from co-combustion of lignite, wood residue, biological sludges from the waste water treatment plant and municipal waste as well with the addition of limestone were examined. Scanning electron microscopy with X-ray microanalyser were used for study of morphology and chemical composition of ash particles. The results were compared with average composition of bottom ashes, fly ashes and input materials found by X-ray fluorescence spectrometry and with phase composition found by X-ray diffraction method. There were proved no significant differences in the character and the structure of individual samples coming from various regimes of combustion., Vladimír Tomášek, Ondřej Šustai, Jana Seidlerová, Zdeněk Klika, Martin Stach, Zdeněk Weiss and Václav Roubíček., and Obsahuje bibliografii
While including gradual long-term flooding of individual residual mining pits, the re-vitalization program of the Podkrušnohorská brown-coal basin area has to assure - beside general water quality standards - satisfactory stability level of future lake banks and their wider environment as required for safe usage of future water lakes. General assessment of factors and conditions influencing bank and/or slope stability of future lakes was realized within the frames of the Czech Republic Academy of Sciences grant project. The grant project solutions include a study of exogenous processes on localities where the mining has been terminated. Also, prognoses were developed on behaviour of future banks during flooding and subsequent operation of future lakes. The presented paper is focused on assessment of mayor factors that participate on initiation and intensity of the bank abrasion and sliding deformations., Tamara Spanilá, Zdeněk Kudrna, Vladislav John, Filip Hartvich and Vladimír Chour., and Obsahuje bibliografické odkazy
Performance of 24h static Precise Point Positioning (PPP) solutions based on multi-GNSS precise satellite orbit and clock products from four analysis centers and seven various constellation combinations was studied to evaluate their quality and characteristics. Data from ten European and four Chinese GNSS stations and 152 days long period from year 2020 were processed. Obtained coordinates were firstly compared with those provided by IGS final weekly combined solution. In Europe, the best agreement with this reference product was reached by solutions including Galileo signals, namely by a combination of GPS+GLONASS+Galileo systems with a mean RMS of 11 mm. This situation was different in China where inclusion of Galileo always led to worse results and the best agreement was achieved by a combination of GPS+GLONASS systems. Although product provided by German Research Center for Geosciences (GFZ) could be selected as the best performing over Europe and product by Center for Orbit Determination in Europe (CODE) over China, differences between individual precise products were mostly at a minimal level. Secondly, coordinates repeatability over the processed period was computed in order to assess the positioning stability. In this regard, the lowest values in both horizontal and vertical direction were reached by GPS+GLONASS solutions. From the perspective of precise products, the repeatability results were dependent on the selected constellation where mainly a specific behavior of product from Wuhan University (WUM) for Galileo system was observed., Weiguo Li and Michal Kačmařík., and Obsahuje bibliografii
A method for estimation of elastic wave velocity anisotropy based on ultrasonic sounding data during rock-sample loading was developed. The subject matter of the method is approximation of ultrasonic sounding data by triaxial velocity ellipsoid. The applicability of proposed method was verified on investigation of anisot ropic rock samples. Laboratory loading of migmatite samples was realized under various mutual orientations between acting force direction and rock foliation - perpendicular, parallel and under 45°. P-ve velocity of ultrasound waves was monitored by 8 sensors network. The velocity ellipsoid was computed and changes of sizes and waorientation its main axes during loading were analyzed for separate experiments with regard to loading level. It was found, that independently to mutual orientation between rock foliation and loading direction, the minimum velocity vector turns to perpendicular direction to final rupture plane and maximum velocity vector turns to the plane of final rupture., Matěj Petružálek, Jan Vilhelm, Tomáš Lokajíček and Vladimír Rudajev., and Obsahuje bibliografické odkazy
The gob side entry retaining with high water material is often used in coal mines. To study the stress evolution characteristics of surrounding rock and asymmetric support control technology of gob side entry retaining with high water material, the evolution law of stress and deformation of surrounding rock in gob side entry retaining during working face mining is studied by theoretical analysis, numerical simulation and field measurement. According to the stress variation of overlying strata during the mining process of the working face, the mechanical models before and after the basic roof fracture were established respectively. The stress and deformation of the filling body and the roof on the side of the filling body are larger, and the stress and deformation of the solid coal and the roof on the side of solid coal are smaller. The maximum stress is at 3 m away from the roadway. The first weighting step distance is 40 m and the periodic weighting step distance is 30 m. Based on the stress and deformation characteristics of the roadway surrounding, the roadway surrounding support is divided into filling bodyside, solid coal side, and middle part of roadway roof. The asymmetric support technology of "filling body+ double row hydraulic prop+ I-beam+ high-strength pretension anchor cable+ high-strength bolt" is proposed. The field engineering practice shows that the surrounding rock control effect of asymmetric support technology with high water material is good., Qiyuan Shan, Yongli Liu, Tao Li and Zhupeng Jin., and Obsahuje bibliografii