GPS (Global Positioning System) technique has become a major tool in contemporary surveying and geodesy. This concerns mostly measurements of horizontal point coordinates, where centimeter-level accuracies are usually required and easily achievable. For the height component, however, these requirements are higher and millimeter-level accuracy is necessary. On the other hand, the intrinsic precision of GPS-derived heights is clearly lower comparing to the horizontal components. This is due to unfavorable satellite geometry, adverse effects of the troposphere or GPS antenna phase center offset and variations. In order to overcome these effects one has to carefully model all the error sources and rigorously process the GPS data. This paper presents studies on the optimal GPS data processing strategy suitable for precise leveling. This was done through the extensive testing and selection of the most appropriate observational session duration, ambiguity resolution strategy, network geometry, troposphere and ionospheric delay reduction methods, signal linear co mbination, elevation angle cut-off, etc. The analyzed processing strategies were evaluated through the processing of a test network. The test network consisted of 19 monitored points and 5 control points, and covered the area of 20 km x 60 km. The obtained results show that the precise GPS leveling with the selected optimal processing strategy allows for about 3 mm repeatability of height measurements when processing 4-hour long sessions. In our opinion GPS leveling may serve as fast and cost-effective replacement of classic geometric leveling, especially in applications where the hei ghts in orthometric or normal height systems are not necessary. This is the case in, e.g., ground deformation studies., Katarzyna Stepniak, Radosław Baryła, Paweł Wielgosz and Grzegorz Kurpinski., and Obsahuje bibliografické odkazy
This paper deals with issues related to convenient monitoring of subsidence due to longtime mining activities of Czech Karviná Mine: Lazy plant, using satellite SAR interferometry (InSAR) techniques. It maintains approaches for optimizations of differential InSAR, especially including available filtering possibilities. It was realized that current SAR satellites were not able to appropriately evaluate deep subsidence as it occurs in Czech mining sites. Other issues are related to the presence of dense vegetation. Data from previous and only available L-band SAR satellite ALOS demonstrates its high potential in this area of interest. However, only a few acquisitions are available of the mining site disallowing usage for purposes of continuous monitoring of subsidence in the area. Processing results of InSAR techniques of the Lazy plant are presented in this paper., Milan Lazecký and Eva Jiránková., and Obsahuje bibliografii
Bertrandon de la Broquière, the spy of Philip the Good, Duke of Burgundy, underwent a long pilgrimage in the Holy Land and Turkey during 1432-1433. In his declining years, in the 1450s, he wrote an account of his travels in the genre of an adventurous memoir entitled Le Voyage d’outre-mer (The Overseas Voyage). His primary task was to follow in the footsteps of his predecessor in espionage Guillebert de Lannoy and gather information that could be used in the next crusade and liberation of Jerusalem. However, he had set a different personal goal for himself: to gather information about the life and faith of the Osman Turks. The unusual nature of Bertrandon’s memoirs accommodated the shift from his original objective. The Overseas Voyage was not intended as a mere handbook for future crusaders and pilgrims; it was also designed to serve as a tool for understanding the “other” world. and Martin Nejedlý.
Films of aliphatic polyurethane-silica nanocomposite containing up to 27.3 mol. % of silica were obtained by the parallel synthesis of both composite components in one common process. This method permits to obtain the nanocomposite materials with the uniform distribution of nanoparticles in the polymer matrix volume. The rise of the silica concentration in the nanocomposite film was shown to lead from one hand to the progressive fall of both the Young’s modulus and yield stress and from another hand to the rise of the ultimate deformation and thermal expansion coefficient values. These effects were ascribed to the formation of the excessive free volume in the material along with the raise of silica concentration., Josif V. Gofman and Ivan V. Abalov., and Obsahuje bibliografii
This study investigates the clay mineralogy of permafrost-affected soils derived from predominantly calcareous loess-like material under the cold ultra-continental climatic conditions of Central Yakutia. These soils are named "Palevye (Pale)" following the Russian Classification, or Cryosols (WRB, 2006). Based on the data obtained, the loess-like substrate of Central Yakutia is enriched by chlorite in comparison with that of the loess-like parent material of European Russia. The clay mineralogy of the fine size fractions (<1μm) of all soil profiles is dominated by a smectitic mineral (most likely random mixed-layer illite-smectite and probably chlorite-smectite where smectite is ≥ 50 %), with subordinate chlorite and illite as well as the products of their transformation with smectite (vermiculite) layers < 50 % in the upper horizons, and finally traces of kaolinite. Pedogenesis has brought about change in the more acidic upper horizons, including a marked reduction in the expandability of the smectitic phase, possibly accounted for by the introduction of non-exchangeable hydroxy-Al into the interlamellar space and / or partial dissolving of smectitic phase, together with a relative reduction in the contents of bothillite and chlorite. Illite has been at least partially transformed to a mixed-layer illite-vermiculite (smectite), whereas chlorite has either been completely decomposed or has transformed to a mixed-layer expandable component. In one profile, the smectitic mineral appears to be absent from the upper horizon, suggesting that it may have been completely decomposed. An alternative explanation is that it has been eluted or translocated down the profile to accumulate in a Bt horizon. The distribution of clay minerals relates to the change of pH values in the profiles (acidic in the upper part, neutral - slightly alkaline in the middle, and alkaline in the basal horizons) possibly determined by seasonal migration of dissolved carbonates., Sofia N. Lessovaia, Sergey V. Goryachkin, Roman V. Desyatkin and Matrena V. Okoneshnikova., and Obsahuje bibliografické odkazy