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31.
Comparison of Galerkin-type discretization techniques for two-phase flow in heterogeneous porous media 总被引:1,自引:0,他引:1
A comparison of Standard Galerkin, Petrov-Galerkin, and Fully-Upwind Galerkin methods for the simulation of two-phase flow in heterogeneous porous media is presented. On the basis of the coupled pressure-saturation equations, a generalized formulation for all three finite element methods is derived and analysed. For flow in homogeneous media, the Petrov-Galerkin method gives excellent results. But this method fails miserably for problems with heterogeneous media. This is because it is not able to capture correctly processes that take place at interfaces when, for instance, the capillary pressure-saturation relationship after Brooks and Corey is assumed. The Fully-Upwind Galerkin method is superior to the Petrov-Galerkin approach because it is able to give correct results for flow in homogeneous and heterogeneous media for the two models of van Genuchten and Brooks-Corey. The widely used formulation which is correct for the homogeneous case cannot be used for heterogeneous media. Instead the straightforward approach of gradpc in combination with a chord-slope technique must be utilized. 相似文献
32.
Rainer Altherr Manfred Schliestedt Martin Okrusch Eberhard Seidel Hans Kreuzer Wilhelm Harre Heinz Lenz Immo Wendt Günther A. Wagner 《Contributions to Mineralogy and Petrology》1979,70(3):245-255
Polymetamorphic rocks of Sifnos (Greece) have been investigated by Rb-Sr, K-Ar, and fission track methods. Critical mineral assemblages from the northern and southernmost parts of Sifnos include jadeite+quartz+3T phengite, and omphacite+garnet +3T phengite, whereas the central part is characterized by the assemblage albite+chlorite+epidote+2M
1 phengite.K-Ar and Rb-Sr dates on phengites (predominantly 3T) of the best preserved high P/itTmetamorphic rocks from northern Sifnos gave concordant ages around 42 m.y., indicating a Late Lutetian age for the high P/T metamorphism. Phengites (2M
1+3T) of less preserved high P/T assemblages yielded K-Ar dates between 48 and 41 m.y. but generally lower Rb-Sr dates. The higher K-Ar dates are interpreted as being elevated by excess argon.K-Ar and Rb-Sr ages on 2M
1 phengites from central Sifnos vary between 24 and 21 m.y. These ages date a second, greenschist-facies metamorphism which overprinted the earlier high-pressure metamorphic rocks. 相似文献
33.
Rainer Wolf Alicia B. Woodrow Richard A.F. Grieve 《Geochimica et cosmochimica acta》1980,44(7):1015-1022
Eleven impact melt and 6 basement rock samples from 4 craters were analyzed by neutron activation for Au, Co, Cr, Fe, Ge, Ir, Ni, Os, Pd, Re and Se. Wanapitei Lake, Ontario: the impact melts show uniform enrichments corresponding to 1–2% C1-chondrite material. Interelement ratios (, , ) suggest that the impacting body was a Cl-, C2-, or LL-chondrite. Nicholson Lake, North West Territory: Ni, Cr and Co are distinctly more enriched than Ir and Au which tentatively suggests an olivine-rich achondrite (nakhlite or ureilite). Gow Lake, Saskatchewan and Mistastin, Labrador: small enrichments in Ir and Ni; both the low ratios and low Cr content suggest iron meteorites, but the signals are too weak for conclusive identification.A tentative comparison of meteoritic signatures at 10 large, ≥4km craters and their presumed celestial counterparts (13 Apollo and Amor asteroids) shows more irons and achondrites among known projectile types, and a preponderance of S-type objects, having no known meteoritic equivalent, among asteroids. It is not yet clear that these differences are significant, in view of the tentative nature of the crater identifications (achondrites in particular), and the limited statistics. 相似文献
34.
H. Rainer 《Rock Mechanics and Rock Engineering》1974,6(2):91-100
ZusammenfassungGibt es Zusammenhänge zwischen Erdbeben und Gebirgsschlaghäufungen im Bergbau Bleiberg Langjährige Beobachtungen beim Bergbau Bleiberg lassen den Schluß zu, daß dieselben Spannungen in der Erdkruste, welche Erdbeben auslösen, auch Gebirgsschlaghäufungen hervorrufen. Im besonderen wirkt sich auf Bleiberg offenbar die durch den Mittelmeerraum führende Erdbebenzone aus. Aber auch Unruhen anderer Teile der Erdkruste, so jene des Karibischen Raumes, scheinen Einfluß zu haben. Von Erdbeben der südamerikanischen Pazifikküste konnte nach unseren Aufzeichnungen kein Einfluß abgeleitet werden.
Vortrag, gehalten während des XXII. Geomechanik-Kolloquiums im Oktober 1973 in Salzburg.
Mit 7 Abbildungen 相似文献
SummaryAre there Connexions Between Earthquakes and the Frequency of Rock Bursts in the Mine of Bleiberg Observations, that were done in the mine of Bleiberg, allow the conclusion, that the same stresses in the earth's crust, which cause earthquakes cause higher frequencies of rock bursts, to. Specially the area of earthquakes around the Mediterranean has effects on Bleiberg. But also other parts of the earth's crust in particular those of the Caribbean area, seem to have their effects. Effects caused by earthquakes of the South-American Pacific-Coast could not be derived from our records.
RésuméRelations entre des tremblements de terre et des coups de rupture de roche Des observations faites durant des années dans la mine de Bleiberg on permis de conclure, que les contraintes dans l'écorce terrestre qui provoque des séismes suscitent également une augmentation de la fréquence des coups de rupture de roche. En particulier, Bleiberg est sous l'influence de la zone sismique de la région de la Méditerranée, mais il semble, que d'autres régions de l'écorce terrestre, par exemple celles de la région caraibe, ont une influence sur la région mentionnée. Par contre selon les enregistrements effectués on a pas pu constaté une influence des séismes de la côte sud-américaine du Pacifique sur cette région.
Vortrag, gehalten während des XXII. Geomechanik-Kolloquiums im Oktober 1973 in Salzburg.
Mit 7 Abbildungen 相似文献
35.
A. J. T. Jull D. Lal S. Taylor R. Wieler A. Grimberg L. Vacher L. R. McHargue S. P. H. T. Freeman C. Maden C. Schnabel S. Xu R. C. Finkel K. J. Kim K. Marti 《Meteoritics & planetary science》2007,42(10):1831-1840
Abstract— We report on studies of the concentrations of cosmogenic nuclides in the magnetic fraction of cosmic dust particles recovered from the South Pole Water Well (SPWW) and from Greenland. Our results confirm that cosmic dust material from these locations contains measurable amounts of cosmogenic nuclides. The Antarctic particles (and possibly those from Greenland as well) also contain minor amounts of solar Ne. Concentrations of cosmogenic nuclides are consistent with irradiation of this material as small objects in space, with exposure ages similar to the expected Poynting‐Robertson (P‐R) lifetimes of 50–200 kyr for particles 25–100 μm in size. 相似文献
36.
37.
S.I. Recca E.R.D. Scott K. Keil R.N. Clayton T.K. Mayeda G.I Huss E. Jarosewich K.S. Weeks F.A. Hasan D.W.G. Sears R. Wieler P. Signer 《Meteoritics & planetary science》1986,21(2):217-229
The Ragland, New Mexico chondrite was found in 1978, and consists of a single stone of 12.16 kg that broke into three pieces. The stone is moderately weathered and has a pronounced chondritic texture. Bulk composition favors an LL classification, and modal analysis and oxygen isotopic composition are consistent with this. The thermoluminescence sensitivity of 0.056 ± 0.020 normalized to Dhajala, compositional variability of olivine (mean Fa 18.3, σ = 10.1) and low-Ca pyroxene (mean Fs 14.6, σ = 6.7), and Ca concentrations in olivine indicate metamorphic subtype 3.4 ± 0.1. The isotopically heavy oxygen composition, which is characteristic of subtypes 3.0–3.1, may be a primary characteristic and not a result of weathering. Low concentrations of radiogenic 40Ar and planetary 36Ar suggest noble gas loss. 相似文献
38.
Klaus KEIL Timothy J. McCOY Lionel WILSON Jean‐Alix BARRAT Doug RUMBLE Matthias M. M. MEIER Rainer WIELER Gary R. HUSS 《Meteoritics & planetary science》2011,46(11):1719-1741
Abstract– We studied the mineralogy, petrology, and bulk, trace element, oxygen, and noble gas isotopic compositions of a composite clast approximately 20 mm in diameter discovered in the Larkman Nunatak (LAR) 04316 aubrite regolith breccia. The clast consists of two lithologies: One is a quench‐textured intergrowth of troilite with spottily zoned metallic Fe,Ni which forms a dendritic or cellular structure. The approximately 30 μm spacings between the Fe,Ni arms yield an estimated cooling rate of this lithology of approximately 25–30 °C s?1. The other is a quench‐textured enstatite‐forsterite‐diopside‐glass vitrophyre lithology. The composition of the clast suggests that it formed at an exceptionally high degree of partial melting, perhaps approaching complete melting, and that the melts from which the composite clast crystallized were quenched from a temperature of approximately 1380–1400 °C at a rate of approximately 25–30 °C s?1. The association of the two lithologies in a composite clast allows, for the first time, an estimation of the cooling rate of a silicate vitrophyre in an aubrite of approximately 25–30 °C s?1. While we cannot completely rule out an impact origin of the clast, we present what we consider is very strong evidence that this composite clast is one of the elusive pyroclasts produced during pyroclastic volcanism on the aubrite parent body ( Wilson and Keil 1991 ). We further suggest that this clast was not ejected into space but retained on the aubrite parent body by virtue of the relatively large size of the clast of approximately 20 mm. Our modeling, taking into account the size of the clast, suggests that the aubrite parent body must have been between approximately 40 and 100 km in diameter, and that the melt from which the clast crystallized must have contained an estimated maximum range of allowed volatile mass fractions between approximately 500 and approximately 4500 ppm. 相似文献
39.
Veronika S. HEBER Roger C. WIENS Amy J. G. JUREWICZ Nadia VOGEL Daniel B. REISENFELD Heinrich BAUR Kevin D. McKEEGAN Rainer WIELER Donald S. BURNETT 《Meteoritics & planetary science》2011,46(4):493-512
Abstract– We report concentrations and isotopic compositions of He, Ne, and Ar measured with high spatial resolution along a radial traverse of a silicon carbide (SiC) quadrant of the Genesis mission concentrator target. The Ne isotopic composition maps instrumental fractionation as a function of radial position in the target: the maximum observed isotopic fractionation is approximately 33‰ per mass unit between the center and periphery. The Ne fluence is enhanced by a factor of 43 at the target center and decreases to 5.5 times at the periphery relative to the bulk solar wind fluence. Neon isotopic profiles measured along all four arms of the “gold cross” mount which held the quadrants in the concentrator target demonstrate that the concentrator target was symmetrically irradiated during operation as designed. We used implantation experiments of Ne into SiC and gold to quantify backscatter loss and isotopic fractionation and compared measurements with numerical simulations from the code “stopping and range of ions in matter.” The 20Ne fluence curve as a function of radial distance on the target may be used to construct concentration factors relative to bulk solar wind for accurate corrections for solar wind fluences of other light elements to be measured in the concentrator target. The Ne isotopic composition as a function of the radial distance in the SiC quadrant provides a correction for the instrumental mass‐dependent isotopic fractionation by the concentrator and can be used to correct measured solar wind oxygen and nitrogen isotopic compositions to obtain bulk solar wind isotopic compositions. 相似文献
40.
Rainer J. Klement 《Astronomy and Astrophysics Review》2010,18(4):567-594
The phase-space structure of our Galaxy holds the key to understand and reconstruct its formation. The ΛCDM model predicts
a richly structured phase-space distribution of dark matter and (halo) stars, consisting of streams of particles torn from
their progenitors during the process of hierarchical merging. While such streams quickly loose their spatial coherence in
the process of phase mixing, the individual stars keep their common origin imprinted into their kinematic and chemical properties,
allowing the recovery of the Galaxy’s individual “building blocks”. The field of Galactic Archeology has witnessed a dramatic
boost over the last decade, thanks to the increasing quality and size of available data sets. This is especially true for
the solar neighborhood, a volume of 1–2 kpc around the sun, where large scale surveys like SDSS/SEGUE continue to reveal the
full 6D phase-space information of thousands of halo stars. In this review, I summarize the discoveries of stellar halo streams
made so far and give a theoretical overview over the search strategies imployed. This article is intended as an introduction
to researchers new to the field, but also as a reference illustrating the achievements made so far. I conclude that disentangling
the individual fragments from which the Milky Way was built requires more precise data that will ultimately be delivered by
the Gaia mission. 相似文献