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Tytuł:
Wstępna charakterystyka petrograficzna kompleksu krystalicznego z kalcyfirami z doliny Sludianki (Bajkał, Rosja)
Preliminary petrographic characteristics of crystalline complex with calciphyres from the Slyudyanka Valley (Baikal Lake, Russia)
Autorzy:
Huber, M.
Lata, L.
Hałas, S.
Powiązania:
https://bibliotekanauki.pl/articles/2061950.pdf
Data publikacji:
2014
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
kalcyfiry
skały metamorficzne
petrografia
dolina Sludianka
calciphyres
metamorphic rocks
petrography
Slyudyanka valley
Opis:
Przedmiotem analizy są skały z doliny znajdującej się w sąsiedztwie kamieniołomu Pieriewał w miejscowości Sludianka, w górach Chamar-Daban. Badania przeprowadzono przy użyciu mikroskopu optycznego i elektronowego z wykorzystaniem metody rentgenografii strukturalnej (XRD). W odsłonięciach, w zboczach doliny, występują łupki krystaliczne, marmury oraz żyły granitoidowe. Znajdują się tam też kalcyfiry bogate we flogopit, apatyt i diopsyd. Kompleks skał metamorficznych został przeobrażony w warunkach facji kordierytowo-biotytowo-almadynowej. Protolitem tych skał były prawdopodobnie osady piaskowcowo-mułowcowe. W utworach tych występują liczne skały węglanowe: diopsydowo-apatytowe kalcyfiry. W procesie odmładzania tektonicznego tego obszaru doszło do deformacji kompleksu skalnego oraz dźwigania go, a także do tworzenia licznych intruzji żyłowych.
Rocks from the Slyudyanka valley (Khamar-Daban Mountain), near the Pierieval quarry, were analysed for petrographic characteristics. Rocks samples have been investigated with the use of optical and electron microscopes as well as XRD methods. The outcrops on the valley slopes reveal the presence of crystalline schists and marbles with granitoid veins. There are also calciphyres, rich in phlogopite, apatite and diopside. This complex was metamorphosed under the cordierite-biotite-almandine facies. In this rock complex, carbonate-diopside-apatite calciphyres are also present. The complex was deformed, uplifted and intruded by numerous granitoid veins during the process of tectonic rejuvenation of this area.
Źródło:
Biuletyn Państwowego Instytutu Geologicznego; 2014, 458; 25--30
0867-6143
Pojawia się w:
Biuletyn Państwowego Instytutu Geologicznego
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Unique siderite occurrence in Baltic Sea: a clue to siderite-water oxygen isotope fractionation at low temperatures
Autorzy:
Hałas, S.
Chlebowski, R.
Powiązania:
https://bibliotekanauki.pl/articles/2058799.pdf
Data publikacji:
2004
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Baltic Sea
siderite
oxygen isotopes
isotope equilibrium
low temperatures
water
Opis:
electron microprobe (determination of major cation content) and mass spectrometry (delta13 C and delta18 O analysis). The siderite was interpreted as having formed from metallic iron partly protected from free oxygen access by wood tar with delta13 C = -24 0/00 and from biogenic CO2 produced from this organic matter. Inasmuch as the siderite has highly positive delta3 C values ranging from 8.05 to 15.41 0/00, we deduced that extremely isotopically heavy CO2 was generated in the process of biogenic decomposition of the organic matter. It was found that the delta18 O values of siderite (26.58 to 27.74‰ vs. VSMOW) fit very well to the recalculated curve of Becker (1971) [formula] and to published extrapolated experimental data.
Źródło:
Geological Quarterly; 2004, 48, 4; 317--322
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The sulphur and oxygen isotopic composition of Lower Cambrian anhydrites in East Siberia
Autorzy:
Peryt, T. M.
Hałas, S.
Kovalevych, V. M.
Petrychenko, O. Y.
Dzhinoridze, N. M.
Powiązania:
https://bibliotekanauki.pl/articles/2058955.pdf
Data publikacji:
2005
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Siberia
Lower Cambrian
evaporites
sulphur isotopes
oxygen isotopes
Opis:
Published sulphur and oxygen isotope age curves for the late Neoproterozoic-Early Cambrian time interval have been based on studies of sulphate intervals of the East Siberian salt giant. We report here on sulphur and oxygen measurements for sulphate dispersed in, or forming laminae in, the rock salt deposits in all Lower Cambrian basins of East Siberia. Sulphur isotope data for 26 samples of Lower Cambrian anhydrites from East Siberia range from +22.6 to +34.5‰. No difference was observed between different suites and between samples taken from anhydrite intercalations in rock salt and from water-insoluble residue in rock salt. Oxygen isotope data for 25 anhydrite samples range from +12.4 to +17.8‰, and thus δ18 O values have a smaller range of variation (5.5‰) than δ34 S (11.8‰) over the entire set of Lower Cambrian anhydrites. The great δ34 S variability observed in the Lower Cambrian of Siberia seems to reflect mixing of sulphates coming from the ocean and due to the riverine input. The lowest δ18 O values may indicate the input values from both the sources, whilst the highest value may result from isotope exchange between SO4 2- and water. Our results combined with data provided by previous workers could indicate a clear stratigraphic trend in δ34 S values, with a remarkable fall of ca. 9‰ in δ34 S value during the earliest Cambrian and then a slight rise in δ34 S values in the younger part of Early Cambrian. However, if only the highest values are taken, the measured values are compatible with seawater δ34 S 3 30‰ during the entire Early Cambrian. Sulphur isotopic composition of sulphate minerals did not be come heavier from the sulphate stage to ward the chloride stage.
Źródło:
Geological Quarterly; 2005, 49, 2; 235--242
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sulphur, oxygen and strontium isotope compositions of Middle Miocene (Badenian) calcium sulphates from the Carpathian Foredeep, Poland: palaeoenvironmental implications
Autorzy:
Kasprzyk, A.
Pueyo, J.J.
Hałas, S.
Fuenlabrada, J.M.
Powiązania:
https://bibliotekanauki.pl/articles/2059523.pdf
Data publikacji:
2007
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Carpathian Foredeep
Badenian
sulphur
oxygen and strontium isotopes
sulphate deposits
Opis:
Sulphur, oxygen and strontium isotope compositions have been measured in sulphate (gypsum and anhydrite) sam ples from the Badenian evaporite complex in the Carpathian Foredeep Basin (Poland) to determine the origin of brines from which these sulphates were formed. Studied samples display the d values from +22.68 to +24.91‰ CDT for sulphur (ten samples) and from +12.26 to +13.63‰ SMOW for oxygen (ten samples), and 87Sr/86Sr ratios from 0.708915 to 0.716329 (six samples). Most samples show isotopic values (both d34S and 87Sr/86Sr) higher than contem poraneous (Badenian) sea water, and thus suggest that these sulphates were formed (i) from brines with a significant component of non-marine waters, (ii) in a restricted system, where an important role was played by meteoric water inputs as well as by bacterial sulphate reduction. The results of this study show clear differences in the isotopic signatures between sedimen tary (gypsum) and diagenetic (anhydrite) lithofacies. While sedimentary gypsum displays sulphur, oxygen and strontium isotope ratios close to contemporaneous (Badenian) sea water, diagenetic anhydrite values are largely elevated. The higher isotopic values (d34S, d18O and 87Sr/86Sr) for anhydrite when compared to gypsum are interpreted as reflecting different hydrological provenances of sulphate in the Badenian basin. Gypsum was formed from brines marine in origin that were subject to an important in flow of continental waters and a local bacterial sulphate reduction in arestricted, and there fore sulphate-limited basin, which is consistent with earlier interpre tations based on sedimentological and geochemical studies. Our study shows that brines from which anhydrite was formed had a highly-radiogenic non-marine (riverine, ground water) strontium component, which is a new contribution to the knowledge on the Badenian sulphate formation. The results reflect a lateral compositional evolution of parent waters during sulphate deposition and diagenesis in the Carpathian Foredeep Basin.
Źródło:
Geological Quarterly; 2007, 51, 3; 285-294
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sulphur and oxygen isotope signatures of late Permian Zechstein anhydrites, West Poland: seawater evolution and diagenetic constraints
Autorzy:
Peryt, T. M.
Halas, S.
Petrivna Hryniv, S.
Powiązania:
https://bibliotekanauki.pl/articles/2059022.pdf
Data publikacji:
2010
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Permian
Zechstein
marine evaporites
sulphate isotopes
Opis:
The stable oxygen and sulphur isotope ratios of 52 anhydrite samples from three Zechstein anhydrite units (Lower Anhydrite, Upper Anhydrite and Basal Anhydrite) of West Poland show d18O values vs. VSMOW in the range of 9.4 to 15.5% (mean of 12.6 š1.3%), and d34S values vs. VCDT between 9.6 to 12.6%o (mean of 11.4 š0.6%o). A generally uniform distribution pattern of both isotopic values throughout the section, although with some random variation, implies that sulphate ions were sufficiently supplied and the basin was open during sulphate deposition. There is a slight stratigraphic differentiation of both the d18O and d34S values: the highest mean values are shown by the Upper Anhydrite and the lowest average values occur in the Basal Anhydrite. The correlation between d18 O and 8 S values is statistically significant only in case of the Basal Anhydrite. A wide range of oxygen isotopic ratios (from 11.6 to 25. l%o), with only several samples having d18O values that fall within the range of late Permian seawater, have been recorded in anhydrite cements and nodules that occur in the Main Dolomite rocks. Sulphur isotope ratios of anhydrite cements (range of 7.6 to 12.9%o, average of 10.7 š1.4%o) tend to reflect the late Permian sulphur isotopic signature of sulphate in seawater. The higher ranges of d18O and d34S values of anhydrite cements and nodules in the Main Dolomite compared to the underlying and overlying anhydrites are due to diagenetic resetting. The conversion of gypsum to anhydrite (often very early and under negligible cover) evidently did not affect the primary marine stratigraphic sulphur isotope composition of the sulphate deposits.
Źródło:
Geological Quarterly; 2010, 54, 4; 387-400
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pochodzenie mineralnych wód chlorkowo-sodowych w rejonie Rzeszowa w świetle badań izotopowych(δ18O i δD, δ13C, δ37CL) i chemicznych
Origin of saline waters in the vicinity of Rzeszów in light of isotope and (δ18O i δD, δ13C, δ3CL) hydrochemical studies
Autorzy:
Baran, A.
Pelc, A.
Chmiel, S.
Hałas, S.
Powiązania:
https://bibliotekanauki.pl/articles/2074915.pdf
Data publikacji:
2012
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
saline waters
Rzeszów region
water derivation
stable isotopes
bicarbonate
chlorine ion
nitrates
wody mineralne
Rzeszów
izotopy trwałe
dwuwęglan
jon chlorkowy
azotany
Opis:
Several decades ago during exploration for additional resources of tap water a saline water deposit (Cl-Na, J, Fe, B type) has been discovered in the area of Rzeszów hospital park. Nowadays this water is exploited for balneological purposes. In the frame-work of this study for the first time the following stable isotopes: (δ18 i δD, δ13C, δ37Cl) and radiocarbon were determined in order to elucidate the origin of water, its mineralization and quality. Oxygen and hydrogen isotope data leads to conclusion that these waters were formed in a warm pre-Pleistocene period or they are mixture of Miocene seawater with Pleistocene infiltration waters. Carbon isotopic composition (b13= –8.65‰) of bicarbonate is characteristic for deep pore waters occurring in sedimentary rocks, whereas distinctly positive and negative δ37 Cl value rather excludes origin of chlorine ion from an open sea basin. Absence of radiocarbon (in Rzeszów well) indicates no admixture of recent infiltration waters, hence these waters are well preserved from anthropogenic pollution. This is further confirmed by very low concentration of nitrate.
Źródło:
Przegląd Geologiczny; 2012, 60, 12; 657--664
0033-2151
Pojawia się w:
Przegląd Geologiczny
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Oxygen isotope analysis of shark teeth phosphates from Bartonian (Eocene) deposits in Mangyshlak peninsula, Kazakhstan
Autorzy:
Pelc, A.
Hałas, S.
Niedźwiedzki, R.
Powiązania:
https://bibliotekanauki.pl/articles/2086536.pdf
Data publikacji:
2011
Wydawca:
Polskie Towarzystwo Mineralogiczne
Tematy:
Bartonian
carbonate
Mangyshlak peninsula
phosphate
shark teeth
δ18O
δ13C
Opis:
We report the results of high-precision (±0.05‰) oxygen isotope analysis of phosphates in 6 teeth of fossil sharks from the Mangyshlak peninsula. This precision was achieved by the offline preparation of CO2 which was then analyzed on a dual-inlet and triple-collector IRMS. The teeth samples were separated from Middle- and Late Bartonian sediments cropping out in two locations, Usak and Kuilus. Seawater temperatures calculated from the δ18O data vary from 23–41oC. However, these temperatures are probably overestimated due to freshwater inflow. The data point at higher temperature in the Late Bartonian than in the Middle Bartonian and suggest differences in the depth habitats of the shark species studied.
Źródło:
Mineralogia; 2011, 42, 1; 53--61
1899-8291
1899-8526
Pojawia się w:
Mineralogia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Origin and Neoholocene evolution of spring-fed fens in Wardzyń, Łódź Upland, central Poland
Autorzy:
Dobrowolski, R.
Ziułkiewicz, M.
Okupny, D.
Forysiak, J.
Bałaga, K.
Alexandrowicz, W. P.
Buczek, A.
Hałas, S.
Powiązania:
https://bibliotekanauki.pl/articles/2060368.pdf
Data publikacji:
2017
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
spring-fed fen
calcareous tufa
peatland
Neoholocene
Łódź Upland
Central Poland
Opis:
Spring-fed fens in Wardzyń represent the rare group of alkaline mires supplied by artesian groundwater. Using multidisciplinary methods (including sedimentological, hydrometric and hydrochemical, pollen, macrofossil, malacological, geochemical, radiocarbon dating, and stable oxygen and carbon isotope analyses) we have been able to (1) reconstruct the main phases of spring-fed fen development, and to (2) determine the cause of Neoholocene groundwater ascension responsible for the mire inception. These phases are characterized by cyclic organic (peat) and carbonate (tufa) sedimentation associated with the Holocene fluctuations in humidity and temperature. The beginning of the activation of hydrological systems (involving the flow of confined groundwater of the Cretaceous aquifer) at Wardzyń occurred in the Subboreal period of the Holocene, after a long episode of decreased humidity initiated ca. 4.2 ka cal BP.
Źródło:
Geological Quarterly; 2017, 61, 2; 413--434
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microfacies, foraminifers and carbon and oxygen isotopes in a basinal section of the Zechstein Limestone (Wuchiapingian): Bonikowo 2 borehole, western Poland
Autorzy:
Peryt, D.
Peryt, T. M.
Hałas, S.
Raczyński, P.
Powiązania:
https://bibliotekanauki.pl/articles/2060535.pdf
Data publikacji:
2016
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Foraminifers
carbon and oxygen isotopes
Wuchiapingian
basin facies
Zechstein Limestone
Polska
Opis:
The Zechstein Limestone of the Bonikowo 2 borehole is composed of limestone with varied dolomite content and is slightly thicker (3.4 m) than other supposed condensed sections in SW Poland. The microfacies (mostly bioclastic wackestones-packstones) are characteristic of open marine limestone deposited in deep shelf environments. The common occurrence of echinoids in all parts of the section, except close to its top, indicates no essential change in sea water salinity. However, the palaeotemperature interpretation of the highest δ18O value of calcite recorded in the Bonikowo 2 borehole (+0.32‰) indicates a temperature of 22.9°C when a δ18O of water = 2‰ is assumed. The δ13C and δ18O curves for calcite and dolomite are similar in shape, and their mean values are similar: +1.8 ±1.5‰ for calcite, respectively, and +1.9 ±2.3‰ and –4.3 ±2.4‰, –3.8 ±4.3‰ for dolomite. There is a recrystallized interval in the lower part of the section with both δ13C and δ18O values reduced. This may be regarded as an aerobic equivalent of the Kupferschiefer. The diversity and abundance of foraminifers is significant throughout the section studied; lagenids prevail, and this is considered to be due to the dysaerobic conditions throughout the duration of deposition of the Zechstein Limestone.
Źródło:
Geological Quarterly; 2016, 60, 4; 827--839
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
K/Ar geochronology of igneous amphibole phenocrysts in Miocene to Pliocene volcaniclastics, Styrian Basin, Austria
Autorzy:
Bojar, H. P.
Bojar, A. V.
Hałas, S.
Wójtowicz, A.
Powiązania:
https://bibliotekanauki.pl/articles/2060550.pdf
Data publikacji:
2013
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
geochronology
igneous amphibole
volcanic tuffs
Styrian Basin
Opis:
We present fifteen new K/Ar ages on amphibole phenocrysts of Neogene volcaniclastic rocks from the Styrian Basin, Austria. The westernmost sub-basin of the Pannonian Basin is the Styrian Basin, which hosts a large number of phreatomagmatic tuff occurrences beside Middle Miocene shield volcanoes and Pliocene effusive alkaline volcanic rocks. The investigated tuffs contain the well-known mantle xenoliths and frequent amphibole and pyroxene phenocrysts. The new K/Ar ages indicate that the Late Miocene phreatomagmatic volcanism started in Pontian (7.51 Ma) and ended in Romanian (2.73 Ma) times. The complete interval of the youngest volcanism in the Styrian Basin covers 5.8 Ma, similar to the volcanism of the western part of the Pannonian Basin and the Nógrád/Novohrad area (West Carpathians). The dated volcanic occurrences display NNW–SSE oriented arrays which are approximately parallel to the Auersbach basinal high zone. The new data indicate that the Late Miocene to Pliocene volcanism of the Styrian Basin is synchronous with the onset of a regional compressional event and eastward tilting of the Styrian basin fill.
Źródło:
Geological Quarterly; 2013, 57, 3; 405--416
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
K/Ar dating and stable isotope analysis of the Baszkówka and Mt. Tazerzait L5 chondrites
Autorzy:
Hałas, S.
Wójtowicz, A.
Powiązania:
https://bibliotekanauki.pl/articles/2059307.pdf
Data publikacji:
2001
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Baszkówka
Tazerzait Mountains
chondrites
K/Ar ages
oxygen isotopes
sulphur isotopes
Opis:
We have determined the content of 40Ar* (1.49 nmol/g) and 4He (1.75 nmol/g) in the Baszkówka meteorite by static vacuum mass spectrometry. The radiogenic argon content was calculated from the measured argon spectrum using the equation: 40Ar* = 40Ar - 295.536Ar assuming a potassium content of 680 ppm wgt. We have obtained K/Ar ages of 3.78 Ga for the chondrules and 3.47 Ga for a bulk sample of Baszkówka. A similar 4He content (1.47 nmol/g) but larger 40Ar* (2.32 nmol/g) content was found for the Mt. Tazerzait bulk sample. The K/Ar age of this meteorite on the basis of the K content (732 ppm) is 4.34 Ga. Sulphur isotope analysis of troilite specimens from both meteorites reveals essentially negative delta 34S values: -1.25š0.06o/oo for Baszkówka and -1.18š0.06o/oo for Mt. Tazerzait expressed on the V-CDT scale. This indicates that both chondrites may have a common origin. The oxygen isotope data (delta 18O = 4.88š0.03o/oo and delta 17O = 3.66š0.10o/oo) suggests that Baszkówka belongs to the L chondrites.
Źródło:
Geological Quarterly; 2001, 45, 3; 315-318
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Diurnal variations and vertical distribution of δ13C, and concentration of atmospheric and soil CO2 in a meadow site, SE Poland
Autorzy:
Szaran, J.
Dudziak, A.
Trembaczowski, A.
Niezgoda, H.
Hałas, S.
Powiązania:
https://bibliotekanauki.pl/articles/2058901.pdf
Data publikacji:
2005
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
SE Poland
atmospheric CO2
carbon dioxide concentration
diurnal observations
delta 13C
soil CO2
Opis:
We provide the results of 24-hour observations made in a meadow site located in a small river valley in Central Europe. Samples of atmospheric air were taken from three horizons: near the soil (0.05 m), in the grass (0.5 m) and above the meadow (2 m) at two-hour intervals. At the same time, samples of soil air were collected from two horizons: -0.1 and -0.5 m. We have found a variation of δ13C above the ground from -6‰ during the day to -20‰ late at night accompanied by variations in CO2 concentration from 270 ppm during the day, to various levels late at night at different heights above the ground. The maximum concentration was 1430 ppm at the ground level. The correlation coefficient between δ 13C and reciprocal of concentration was the highest (R2 = 0.984) for the samples collected 2 m above the ground, the regression line clearly indicating CO2 mixing from the two sources: atmospheric and biogenic reservoirs. The intercept of the mixing line yields δC = -23.0‰ for the biogenic CO2. In contrast, the diurnal variations in the soil were relatively small, δ13C varied from -21.6 to -23.4‰, while CO2 concentration from 4300 to 8200 and from 24 700 to 34 500 ppm at depths of 0.1 m and 0.5 m respectively, which is less than 2-fold. Small diurnal variations are characteristic of dry soils, where δ13C is weakly correlated with CO2 concentration (in our case R2 was 0.30 and 0.54, respectively).
Źródło:
Geological Quarterly; 2005, 49, 2; 135--144
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Concentration of soil CO2 as an indicator of the decalcification rate after liming treatment
Autorzy:
Chmiel, S.
Halas, S.
Glowacki, S.
Sposob, J.
Maciejewska, E.
Trembaczowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/26239.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
carbon dioxide
carbon dioxide concentration
soil
decalcification
liming treatment
water infiltration
leaching
Źródło:
International Agrophysics; 2016, 30, 2
0236-8722
Pojawia się w:
International Agrophysics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Carbon-13 in alpha-cellulose of oak latewood (Jędrzejów, Southern Poland) during the Maunder Minimum
Autorzy:
Pazdur, A.
Korput, S.
Fogtman, M.
Szczepanek, M.
Hałas, S.
Krąpiec, M.
Szychowska-Krąpiec, E.
Powiązania:
https://bibliotekanauki.pl/articles/2058897.pdf
Data publikacji:
2005
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
13C isotope
alpha-cellulose
Maunder Minimum
tree-rings
Opis:
We have studied the δ13C signature in latewood alpha-cellulose of an ancient oak (Quercus robur L.) from a Cisterian Abbey belfry in Jędrzejów (Southern Poland). The time scale for the delta 13C record during 1631-1765 AD was built on the basis of detailed dendrochronology studies. Techniques available for extraction of alpha-cellulose from small samples have been used, the mean value of alpha-cellulose extraction efficiency being ca. 35%. In the delta 13C record of alpha-cellulose the cooling between 1650-1700 AD is clearly visible as a decrease of about 1.5‰. This period is consistent with the interval of the lowest solaractivity between 1645 and 1715 AD, which is known as the Maunder Minimum. Anti-correlation between δ13C and δ13C during the Maunder Minimum was observed but δ13C record is delayed by about 30 years with respect to the Maunder Minimum.
Źródło:
Geological Quarterly; 2005, 49, 2; 165-172
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Badanie składowych prądów i momentu w celu wykrywania złożonych uszkodzeń trójfazowej maszyny indukcyjnej
Investigation of current and torque components in order to detect complicated damages of three-phase induction machine
Autorzy:
Hałas, T.
Nowak, M.
Rawicki, S.
Powiązania:
https://bibliotekanauki.pl/articles/377209.pdf
Data publikacji:
2018
Wydawca:
Politechnika Poznańska. Wydawnictwo Politechniki Poznańskiej
Tematy:
trójfazowa maszyna indukcyjna
złożone uszkodzenia w stojanie
i wirniku
diagnostyczne składowe prądów i momentu
symulacje komputerowe
Opis:
W artykule opracowano metodę diagnostyczną dla złożonych uszkodzeń trójfazowej maszyny indukcyjnej, które rozwijają się zarówno w obwodzie stojana, jak i w wirniku. Ich wczesne wykrycie ma istotne znaczenie, gdyż staje się możliwe zapoczątkowanie systematycznego badania w trybie on-line rozwoju stopnia uszkodzenia i zaplanowanie remontu w dogodnym czasie. Wprowadzono metodę obliczania składowych prądów i momentu, których częstotliwość i amplituda mogą spełniać funkcję symptomów diagnostycznych pozwalających na ocenę rodzaju stanu awaryjnego oraz określanie stopnia uszkodzenia. Dla dwustronnej niesymetrii w stojanie i wirniku opracowano model matematyczny trójfazowej maszyny indukcyjnej przy wykorzystaniu zastępczego układu uzwojeń dwufazowych. Dla stanów ustalonych i nieustalonych maszyny wykonano przykładowe symulacje komputerowe, potwierdzające przydatność opracowanej metody.
The paper deals with the diagnostic method elaborated for complicated damages of the three-phase induction machine; these faults appear both in the stator and in the rotor circuit. Early faultfinding is of great importance because it makes possible initation of the systematic on-line investigation of development of the damage degree and planning the repair in favourable time. The method of the calculation of current and torque components has been elaborated. The frequency and the amplitude of these quantities can fulfil a function of diagnostic symptoms making possible the determination of the type and degree of the fault. For two-sided asymmetry in the stator and in the rotor, the mathematical model of the three-phase induction machine has been elaborated using the equivalent system of two-phase windings. For the steady and transient states of the machine, the exemplary computer simulations were realized and the results of calculations have been confirmed usefulness of the elaborated method.
Źródło:
Poznan University of Technology Academic Journals. Electrical Engineering; 2018, 95; 187-198
1897-0737
Pojawia się w:
Poznan University of Technology Academic Journals. Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 19

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