Geodetic VLBI with an artificial radio source on the Moon: a simulation study     

Grzegorz Klopotek  Thomas Hobiger  Rüdiger Haas 《Journal of Geodesy》2018,92(5):457-469

We perform extensive simulations in order to assess the accuracy with which the position of a radio transmitter on the surface of the Moon can be determined by geodetic VLBI. We study how the quality and quantity of geodetic VLBI observations influence these position estimates and investigate how observations of such near-field objects affect classical geodetic parameters like VLBI station coordinates and Earth rotation parameters. Our studies are based on today’s global geodetic VLBI schedules as well as on those designed for the next-generation geodetic VLBI system. We use Monte Carlo simulations including realistic stochastic models of troposphere, station clocks, and observational noise. Our results indicate that it is possible to position a radio transmitter on the Moon using today’s geodetic VLBI with a two-dimensional horizontal accuracy of better than one meter. Moreover, we show that the next-generation geodetic VLBI has the potential to improve the two-dimensional accuracy to better than 5 cm. Thus, our results lay the base for novel observing concepts to improve both lunar research and geodetic VLBI.  相似文献   

Cerium and Ytrium in apatite as records of magmatic processes: Insight into fractional crystallization,magma mingling and fluid saturation     

Arkadiusz Przybyło  Anna Pietranik  Grzegorz Zieliński 《Chemie der Erde / Geochemistry》2022,82(2):125864

Apatite is a versatile mineral crystallizing at different stages of silicic magma evolution. Its composition may record that of magma, but could also be affected by interaction with fluids. The focus of this study is the well-recognized magma mingling process that was previously detected using plagioclase composition and in this study complementary record is sought in apatite. The apatite was analysed in two dioritic enclaves (primitive and hybrid) and host quartz monzonite, which is an igneous rock emplaced at ca. 340 Ma in mylonitized Góry Sowie gneisses (NE Bohemian Massif). The apatite was analysed in-situ by microprobe that allowed for chemical characterization of different apatite populations in quartz monzonite and analyses of thin acicular apatite in the enclaves. Apatite population in the quartz monzonite was chemically distinct from that in both enclave types and characterized by higher Y and lower Ce contents, such values are usually typical for peraluminous magmas. As such, the apatite transfer from felsic to mafic magma should be well recorded in apatite composition, which was not the case. Monzonite apatite composition was not commonly observed in the hybrid enclave despite massive plagioclase transfer and only rare resorbed cores with low Ce and Y contents were present. However, such low Ce and Y cores crystalized at the latest stage of apatite crystallization in the quartz monzonite, whereas the plagioclase transfer was an early episode. Therefore, we conclude that apatite transfer was limited during mingling and the apatite composition in the quartz monzonite is best explained by an early Cl-Ce-rich fluid removal and then fractional crystallization, while apatite in the primitive enclave is affected only by fractional crystallization. Altogether, Ce and Y composition of apatite is a valuable tool to record diverse magmatic processes such as fluid removal and precipitation from fluid in addition to fractionation of different REE phases and should be further explored.  相似文献   

Infragravity waves at a dissipative coast; evidence upon multi-resolution analysis     

Grzegorz Różyński 《Coastal Engineering》2007

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Comparative study of radiation-induced damage in magnesium aluminate spinel by means of IL,CL and RBS/C techniques     

Iwona Jozwik  Jacek Jagielski  Grzegorz Gawlik  Przemyslaw Jozwik  Renata Ratajczak  Gerard Panczer  Nathalie Moncoffre  Anna Wajler  Agata Sidorowicz  Lionel Thomé 《Physics and Chemistry of Minerals》2016,43(6):439-445

A comparative study of damage accumulation in magnesium aluminate spinel (MgAl₂O₄) has been conducted using ionoluminescence (IL), cathodoluminescence (CL) and Rutherford Backscattering Spectrometry/channeling (RBS/C) techniques. MgAl₂O₄ single crystal and polycrystalline samples were irradiated with 320 keV Ar⁺ ions at fluencies ranging from 1 × 10¹² to 2 × 10¹⁶ cm^?2 in order to create various levels of radiation damage. RBS/C measurements provided quantitative data about damage concentration in the samples. These values were then compared to the luminescence measurements. The results obtained by IL and RBS/C methods demonstrate a two-step character of damage buildup process. The CL data analysis points to the three-step damage accumulation mechanism involving the first defect transformation at fluencies of about 10¹³ cm^?2 and second at about 10¹⁵ cm^?2. The rate of changes resulting from the formation of nonluminescent recombination centers is clearly nonlinear and cannot be described in terms of continuous accumulation of point defects. Both, IL and CL techniques, appear as new, complementary tools bringing new possibilities in the damage accumulation studies in single- and polycrystalline materials.  相似文献   

The usability of the undifferenced positioning techniques in establishing regional geodetic control networks: a case study in Poland     

Grzegorz Krzan 《Studia Geophysica et Geodaetica》2018,62(1):17-37

Recently undifferenced Precise Point Positioning (PPP) technique has become a subject of interest not only among researchers, but also satellite positioning practitioners like surveyors and engineers. Along with the development of precise clocks and orbits products, and the improvement of models mitigating interfering phenomena like atmospheric refraction, PPP has become an alternative to relative positioning in many field applications. This study concerns the usability of Undifferenced Positioning techniques in establishing geodetic control networks. Satellite observations from 13 stations equipped with high-end receivers and survey grade commercial receivers were processed using the NAvigation Package for Earth Observation Satellites -NAPEOS v. 3.3.1. In the study the standard PPP (float) and Undifferenced Network solution with clocks/orbits fixed strategies of post-processing were carried out using various observing intervals (30 min., 1 h, 2 h, 4 h, daily). The high accuracy results obtained with PPP and UD Network solution predisposes these strategies for the use in surveying tasks requiring even centimeter positioning accuracy.  相似文献   

Geomorphic and hydrological controls on groundwater dolocrete formation in the semi-arid Hamersley Basin,northwest Australia     

Caroline C. Mather  David J. Nash  Shawan Dogramaci  Pauline F. Grierson  Grzegorz Skrzypek 《地球表面变化过程与地形》2019,44(14):2752-2770

Groundwater dolocretes may exert an important geomorphic control on landscape evolution within sub-humid to arid regions. However, the geomorphic and hydrogeological settings of dolocrete remain poorly described. The hydrochemical conditions of dolomite precipitation in groundwater environments are also not well known. Classic models of dolocrete formation explain dolomite precipitation from highly evolved groundwaters at the terminus of major drainage but do not explain dolocrete distributed in regionally elevated landscapes, upgradient of major drainage. This study investigated the mineralogy, micromorphology and stable carbon and oxygen isotope compositions of three dolocrete profiles within a regionally elevated sub-basin of the Hamersley Ranges in the Pilbara region of northwest Australia. We sought to establish the environmental and hydrochemical conditions and present a model for dolocrete formation. We found that dolocrete formed within zones of emerging groundwater under saline-evaporitic conditions within internally draining sub-basins, most likely during the Late Miocene and Pliocene. Saline-evaporitic conditions were indicated by: (i) the mineralogy, dominated by dolomite, palygorskite and smectite; (ii) desiccation features and the presence of phreatic and vadose cements, indicative of a shallow fluctuating water table, and; (iii) dolomite δ¹⁸O values (median = –5.88 ‰). Dolomite precipitation was promoted by evaporation and carbon dioxide degassing from shallow magnesium (Mg)-rich groundwater. These factors appear to have been the major drivers of dolocrete development without a requirement for significant down-dip hydrochemical modification. Primary dolomite precipitation was possible due to the presence of microbial extracellular polymeric substances (EPS). EPS provided negatively charged nucleation sites, which bound Mg²⁺, overcoming kinetic effects. High microbial activity within groundwater systems suggest these processes may be important for dolocrete formation worldwide and that groundwater dolocretes may be more pervasive in landscapes than currently recognized. © 2019 John Wiley & Sons, Ltd. © 2019 John Wiley & Sons, Ltd.  相似文献   

Pesticides from the EU First and Second Watch Lists in the Water Environment     

Damian Pietrzak  Jaros&#x;aw Kania  Grzegorz Malina  Ewa Kmiecik  Katarzyna W&#x;tor 《洁净——土壤、空气、水》2019,47(7)

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Geochronological constraints on Caledonian strike–slip displacement in Svalbard,with implications for the evolution of the Arctic     

Karol Faehnrich  Jaros&#x;aw Majka  David Schneider  Stanis&#x;aw Mazur  Maciej Manecki  Grzegorz Ziemniak  Virginia T. Wala  Justin V. Strauss 《地学学报》2020,32(4):290-299

The timing of Svalbard's assembly in relation to the mid‐Paleozoic Caledonian collision between Baltica and Laurentia remains contentious. The Svalbard archipelago consists of three basement provinces bounded by N–S‐trending strike–slip faults whose displacement histories are poorly understood. Here, we report microstructural and mineral chemistry data integrated with ⁴⁰Ar/³⁹Ar muscovite geochronology from the sinistral Vimsodden‐Kosibapasset Shear Zone (VKSZ, southwest Svalbard) and explore its relationship to adjacent structures and regional deformation within the circum‐Arctic. Our results indicate that strike–slip displacement along the VKSZ occurred in late Silurian–Early Devonian and was contemporaneous with the beginning of the main phase of continental collision in Greenland and Scandinavia and the onset of syn‐orogenic sedimentation in Silurian–Devonian fault‐controlled basins in northern Svalbard. These new‐age constraints highlight possible links between escape tectonics in the Caledonian orogen and mid‐Paleozoic terrane transfer across the northern margin of Laurentia.  相似文献   

The use of a novel Vibrio harveyi luminescence mutagenicity assay in testing marine water for the presence of mutagenic pollution     

Podgórska B  Pazdro K  Pempkowiak J  Wegrzyn G 《Marine pollution bulletin》2007,54(6):808-814

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Closed coal mine shaft as a source of carbon dioxide emissions     

Paweł Wrona  Zenon Różański  Grzegorz Pach  Tomasz Suponik  Marcin Popczyk 《Environmental Earth Sciences》2016,75(15):1139

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