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Wyszukujesz frazę "Stępniewski, J." wg kryterium: Autor


Wyświetlanie 1-6 z 6
Tytuł:
Mineralogy of the Baszkówka chondrite (L5 S1): new data on silicates, opaques and minor minerals
Autorzy:
Borucki, J.
Stępniewski, M.
Powiązania:
https://bibliotekanauki.pl/articles/2059302.pdf
Data publikacji:
2001
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Baszkówka
meteorites
ordinary chondrites
minerals
spinel
picotite
Opis:
The mineral composition of the Baszkówka meteorite comprises: olivine, pyroxenes, plagioclase, Fe,Ni metal, troilite and chromite with minor chlorapatite, whitlockite, magnetite, haematite, spinel, idaite, calcite and native Cu. A rare variety of spinel (picotite), probably the oldest among the minerals of Baszkówka, was identified in the only two chondrules named: panda and chevron. The composition of the olivine (Fa 26.2š1.8 wt.%) and the high degree of chondrite homogenisation, a result of thermal metamorphism, are consistent with earlier results and indicate the L5 group. No distinct shock effects were observed in Baszkówka, classified as S1. Troilite-Fe,Ni and Fe,Ni metal lumps are defined and interpreted as molten planetesimals impact splashes.
Źródło:
Geological Quarterly; 2001, 45, 3; 229-256
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pseudometeorite from Łapino (Pomerania, North Poland)
Autorzy:
Stępniewski, M.
Borucki, J.
Powiązania:
https://bibliotekanauki.pl/articles/2059303.pdf
Data publikacji:
2001
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Łapino
morth Poland
iron silicide
pseudometeorite
Opis:
A boulder, found in a gravel pit by Łapino near Gdańsk in 1954, was noted as unusual. Among various erratics ice-derived from Scandinavia in the Quaternary, this one had an extraordinary appearance; unusually dark, heavy and strongly magnetic. An extraterrestrial origin was suggested. The border resembles an intrusive breccia with numerous periclase-bearing fragments in a magnetite-clinopyroxene-olivine matrix. A single grain with a metallic luster, a few centimetres in diameter, was identified as the iron silicide (Fe3Si). Only two natural occurrences of iron silicide have been described, both from meteorites. However, the isotopic analysis showed an absence of radiogenic nuclides (10Be, 26Al, 36Cl), and the ratio of oxygen isotopes (delta 17O and delta 18O) suggested a terrestrial origin. Thus the stone is probable artifact, presumably the product of an unidentified foundry.
Źródło:
Geological Quarterly; 2001, 45, 3; 343-348
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Two spinel-bearing compound chondrules from the Baszkówka meteorite
Autorzy:
Borucki, J.
Stępniewski, M.
Powiązania:
https://bibliotekanauki.pl/articles/2059304.pdf
Data publikacji:
2001
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Baszkówka
meteorites
ordinary chondrites
spinel
Opis:
The present paper describes two compound chondrules labelled panda and chevron, discovered in the Baszkówka meteorite. Optical microscope, electron microscope and electron microprobe studies revealed an unusual mineral composition and fabric. Both chondrules include "primary" and "secondary" components. The panda and chevron chondrules have apparent diameters of ~0.86 and ~0.54 mm respectively with spinel dominant in primary components and olivine-plagioclase in secondary components overlain by thin microcrystalline rims. Euhedral or subhedral Mg, Fe2+/Al, Cr-spinel crystals from the panda's primary component (zoned, cavernous or homogeneous) were not found in Mg-Fe chondrules in Baszkówka, where Cr occurs exclusively as chromite. Olivine crystals from panda's primary (Fa27.1) and secondary (Fa26.5) component have similar compositions to those from panda's rim (Fa26.4) and comparable to olivine from other Baszkówka Mg-Fe chondrules (average ~Fa25.7). The Ca-plagioclase laths from the groundmass of panda's primary component has an extremely variable composition (~An49 to ~An60), evidently more calcic than those in other chondrules of the meteorite (mean ~An13). The primary components of the two spinel-bearing chondrules may have been formed in a fireball generated by powerful impact during early accretion of a protoplanet. After crystallisation the spinel crystals were abraded and polished, probably during rapid flight through a dense cloud of interplanetary dust. The moderately reducing conditions of the hypothetical fire ball were replaced by a more reducing environment during the condensation of the rims of both chondrules.
Źródło:
Geological Quarterly; 2001, 45, 3; 281-288
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Songyuan ordinary chondrite (China) - rich in alien rock fragments and its reclassification
Autorzy:
Borucki, J.
Giro, L.
Orłowski, R.
Stępniewski, M.
Powiązania:
https://bibliotekanauki.pl/articles/2059203.pdf
Data publikacji:
2009
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Songyuan
meteorites
ordinary chondrites
classification
rock fragments
Opis:
The Songyuan chondrite is composed mostly of minerals and chondrule types common in equilibrated ordinary chondrites. More distinctively, the Songyuan material includes numerous sintered cryptocrystalline rock lumps, possible chondrule precursors, and less frequent fragments of olivine-pyroxene basalt. The moderate porosity (estimated under the polarizing microscope at a few percent by volume) and un compacted metal grains, suggest that the meteorite came from very shallow horizons of the regolith. The shallow original position of the Songyuan fragment on its parent body is consistent also with the abundance of numerous euhedral crystals of the main meteoritic components present in the interstitial pores. They crystallized most probably from fluids migrating through the superficial horizons from the in ner parts of the Songyuan parent body. The structural characteristics and slight differentiation in olivine composition suggests a high degree of homogenization and, together with the median value of the fayalite content (26.2 š0.24 wt.%), corre sponds to the L5 chemical-petrologic group of equilibrated ordinary chondrites. More over, the homogenous extinction in the olivine crystals and the absence of multiple planar fractures indicate the lowest level of the shock metamorphism (S1), whereas the lack of any oxide rims around kamacite and troilite grains points to the lowest level of weathering (W0).
Źródło:
Geological Quarterly; 2009, 53, 2; 187-198
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Network-on-Multi-Chip (NoMC) with Monitoring and Debugging Support
Autorzy:
Łuczak, A.
Stępniewski, M.
Siast, J.
Domański, M.
Stankiewicz, O.
Kurc, M.
Konieczny, J.
Powiązania:
https://bibliotekanauki.pl/articles/307888.pdf
Data publikacji:
2011
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
debugging
FPGA
multi-chip
video coding
Opis:
This paper summarizes recent research on network-on-multi-chip (NoMC) at Poznań University of Technology. The proposed network architecture supports hierarchical addressing and multicast transition mode. Such an approach provides new debugging functionality hardly attainable in classical hardware testing methodology. A multicast transmission also enables real-time packet monitoring. The introduced features of NoC network allow to elaborate a model of hardware video codec that utilizes distributed processing on many FPGAs. Final performance of the designed network was assessed using a model of AVC coder and multi-FPGA platforms. In such a system, the introduced multicast transmission mode yields overall gain of bandwidth up to 30%. Moreover, synthesis results show that the basic network components designed in Verilog language are suitable and easily synthesizable for FPGA devices.
Źródło:
Journal of Telecommunications and Information Technology; 2011, 3; 81-86
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative Mössbauer studies of the Baszkówka ordinary chondriteand some other meteorites
Autorzy:
Gałązka-Friedman, J.
Bauminger, E. R.
Nowik, I.
Bakun-Czubarow, N.
Stępniewski, M.
Siemiątkowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/2059308.pdf
Data publikacji:
2001
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
ordinary chondrites
parent body
Mössbauer spectroscopy
Q angle
troilite
kamacite
olivine
pyroxene
weathering
oxidation
Opis:
It was suggested that perhaps Mössbauer parameters of troilite could serve as a criterion for an interpretation of the origin of various meteorites. It was found that in three meteorites coming from the same parent body (Baszkówka, Mt. Tazerzait and Songyuan) the angle between the principal axis of the electric field gradient (EFG) and the direction of the magnetic field in troilite is around 60o. Further investigations showed that in some other meteorites, not belonging to this group, this angle is close to 90o.
Źródło:
Geological Quarterly; 2001, 45, 3; 319-326
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-6 z 6

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