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231.
A simple and exact numerical scheme for long-term simulations of 3D potential fully nonlinear periodic gravity waves is suggested. The scheme is based on the surface-following nonorthogonal curvilinear coordinate system. Velocity potential is represented as a sum of analytical and nonlinear components. The Poisson equation for the nonlinear component of velocity potential is solved iteratively. Fourier transform method, the second-order accuracy approximation of vertical derivatives on a stretched vertical grid and the fourth-order Runge–Kutta time stepping are used. The scheme is validated by simulation of steep Stokes waves. A one-processor version of the model for PC allows us to simulate evolution of a wave field with thousands degrees of freedom for hundreds of wave periods. The scheme is designed for investigation of nonlinear 2D surface waves, generation of extreme waves, and direct calculations of nonlinear interactions. 相似文献
232.
Corinne Casiot Marion Egal Françoise Elbaz-Poulichet Odile Bruneel Chrystelle Bancon-Montigny Marie-Ange Cordier Elena Gomez Catherine Aliaume 《Applied Geochemistry》2009
Dissolved and particulate concentrations of metals (Fe, Al, Mn, Co, Ni, Cu, Zn, Cd, Tl, Pb) and As were monitored over a 5 year period in the Amous River downstream of its confluence with a creek severely affected by acid mine drainage (AMD) originating from a former Pb–Zn mine. Water pH ranged from 6.5 to 8.8. Metals were predominantly in dissolved form, except Fe and Pb, which were in particulate form. In the particulate phase, metals were generally associated with Al oxides, whereas As was linked to Fe oxides. Metal concentrations in the dissolved and/or particulate phase were generally higher during the wet season due to higher generation of AMD. Average dissolved (size < 0.22 μm) metal concentrations (μg/L) were 1 ± 4 (Fe), 69 ± 49 (Al), 140 ± 118 (Mn), 4 ± 3 Co, 6 ± 4 (Ni), 1.3 ± 0.8 (Cu), 126 ± 81 (Zn), 1.1 ± 0.7 (Cd), 0.9 ± 0.5 (Tl), 2 ± 3 (Pb). Dissolved As concentrations ranged from 5 to 134 μg/L (30 ± 23 μg/L). During the survey, the concentration of colloidal metals (5 kDa < size < 0.22 μm) was less than 25% of dissolved concentrations. Dissolved metal concentrations were generally higher than the maximum concentrations allowed in European surface waters for priority substances (Ni, Cd and Pb) and higher than the environmental quality standards for other compounds. Using Diffusion Gradient in Thin Film (DGT) probes, metals were shown to be in potentially bioavailable form. The concentrations in Leuciscus cephalus were below the maximum Pb and Cd concentrations allowed in fish muscle for human consumption by the European Water Directive. Amongst the elements studied, only As, Pb and Tl were shown to bioaccumulate in liver tissue (As, Pb) or otoliths (Tl). Bioaccumulation of metals or As was not detected in muscle. 相似文献
233.
A petrological and geochemical study on time-series samples from Klyuchevskoy volcano,Kamchatka arc 总被引:1,自引:0,他引:1
Olga?Bergal-Kuvikas Mitsuhiro?NakagawaEmail author Takeshi?Kuritani Yaroslav?Muravyev Nataliya?Malik Elena?Klimenko Mizuho?Amma-Miyasaka Akiko?Matsumoto Shunjiro?Shimada 《Contributions to Mineralogy and Petrology》2017,172(5):35
To understand the generation and evolution of mafic magmas from Klyuchevskoy volcano in the Kamchatka arc, which is one of the most active arc volcanoes on Earth, a petrological and geochemical study was carried out on time-series samples from the volcano. The eruptive products show significant variations in their whole-rock compositions (52.0–55.5 wt.% SiO2), and they have been divided into high-Mg basalts and high-Al andesites. In the high-Mg basalts, lower-K and higher-K primitive samples (>9 wt.% MgO) are present, and their petrological features indicate that they may represent primary or near-primary magmas. Slab-derived fluids that induced generation of the lower-K basaltic magmas were less enriched in melt component than those associated with the higher-K basaltic magmas, and the fluids are likely to have been released from the subducting slab at shallower levels for the lower-K basaltic magmas than for higher-K basaltic magmas. Analyses using multicomponent thermodynamics indicates that the lower-K primary magma was generated by ~13% melting of a source mantle with ~0.7 wt.% H2O at 1245–1260?°C and ~1.9 GPa. During most of the evolution of the volcano, the lower-K basaltic magmas were dominant; the higher-K primitive magma first appeared in AD 1932. In AD 1937–1938, both the lower-K and higher-K primitive magmas erupted, which implies that the two types of primary magmas were present simultaneously and independently beneath the volcano. The higher-K basaltic magmas evolved progressively into high-Al andesite magmas in a magma chamber in the middle crust from AD 1932 to ~AD 1960. Since then, relatively primitive magma has been injected continuously into the magma chamber, which has resulted in the systematic increase of the MgO contents of erupted materials with ages from ~AD 1960 to present. 相似文献
234.
Elena Kapogianni Michael Sakellariou Jan Laue 《Geotechnical and Geological Engineering》2017,35(2):585-605
The purpose of this experimental investigation is to obtain strain measurements via optical fibre sensors in the drum geotechnical centrifuge of ETH Zurich. It is part of a test series with main goal to study the behaviour of reinforced slopes subjected to self weight loading and subsequently to an impact from a rockfall event. In total 13 scaled reinforced slope models were built with a height of 180 mm and a slope inclination of 2V:1H, optimising the materials used and the different ways of model making. The maximum g-levels were 50 and 100 g and the impact loading was applied at 50 g. The optical fibre sensors were placed on various layers of the reinforcement and at different positions. Strain measurements that were recorded during different tests are logical and expected, demonstrating that optical fibre sensors can successfully be used for measuring linear strain on reinforcement layers that are tested under enhanced gravity in the geotechnical centrifuge. The experimental set up as well as the opportunities and challenges of these measurements are presented and discussed. Finally, correspondent prototype numerical models were created and analysed and the results of this analysis are compared to the corresponding experimental ones. 相似文献
235.
Michail I. Gladyshev Nadezhda N. Sushchik Olesia N. Makhutova Olga P. Dubovskaya Elena S. Kravchuk Galina S. Kalachova Elena B. Khromechek 《Limnologica》2010,40(4):343-357
During two sampling seasons we analyzed on weekly basis fatty acid (FA) composition of seston fraction <130 μm and zooplankton fraction >130 μm, and compared them using a multivariate canonical correlation analysis (CCA). Besides, we evaluated a possible impact of water temperature and inorganic nutrients on FA composition of the seston and the zooplankton.In spite of significant differences in percentages of several individual FAs, we found very strong canonical correlation (cross-correlation, 1-week lag) between FA composition of the seston and the zooplankton. The most important factor, providing the overall canonical cross-correlation between FA profiles of the seston and the zooplankton fractions was eicosapentaenoic acid (20:5ω3, EPA). FA composition of the zooplankton fraction had comparatively poor correlations with taxonomic composition of the zooplankton. Thus, seasonal variations of FA composition of the zooplankton were determined primarily by seasonal changes in FA composition of the seston, rather than by taxonomic differences of FA profiles between rotifers, cyclopoids and cladocerans. FA composition of the seston was strongly affected by its taxonomic composition, namely by that of phytoplankton. According to CCA, the highest factor loadings pertained to diatoms interacting with their marker acids, including EPA, and cyanobacteria and greens, interacting with their marker acids. Ciliates and small rotifers composed considerable and sometimes major part of the seston biomass, but according to CCA their contributions to seasonal variations of the total FA profile of the seston were insignificant. This finding indirectly support the conclusion of the other authors, that the main source of FAs presented in ciliates and rotifers must be sought in algae and that they do not modify FA composition of food consumed, apart from repackaging it.Water temperature was the principal environmental parameter which drove the overall variations of FA composition. Factor loadings for the inorganic nutrients were comparatively negligible. The main contribution in the seasonal variation of FA composition of the seston was given by negative interaction between water temperature and percentage of EPA in the seston. 相似文献
236.
237.
Júlia Dégi Rainer Abart Kálmán Török Dieter Rhede Elena Petrishcheva 《Mineralogy and Petrology》2009,95(3-4):219-234
We investigate the effects of xenolith–host basalt interaction on lower crustal mafic granulite xenoliths from the Central Pannonian Basin. The xenoliths are devoid of any signs of melting, nevertheless various phenomena are identified, which indicate that the original mineralogy and chemistry of the xenoliths was modified during interaction with the host basalt. The rock-forming silicates are only slightly affected by alteration, but the Fe–Ti-oxides are overprinted to a significant extent. Complex chemical zoning patterns are detected using high-resolution element mapping in ilmenites and in lamellar titanomagnetite–ilmenite intergrowths. The chemical alteration of the Fe–Ti-oxides was diffusion-controlled and, hence, time and temperature dependent. On the basis of diffusion profiles in titanomagnetite we estimate the duration of xenolith–host basalt interaction to be at least 9–20 h. This is comparable to the time necessary for the ascent of the host basalt to the surface. It is too short to reflect alteration during granulite facies metamorphism in the deep crust. The chemical alteration of the titanomagnetite thus reflects the total duration of the xenolith–host basalt interaction. 相似文献
238.
Guillermo F. Hägele † Ángeles I. Díaz ‡ Elena Terlevich § Roberto Terlevich ‡ Enrique Pérez-Montero ¶ Mónica V. Cardaci 《Monthly notices of the Royal Astronomical Society》2008,383(1):209-229
We present high signal-to-noise ratio spectrophotometric observations of seven luminous H ii galaxies. The observations have been made with the use of a double-arm spectrograph which provides spectra with a wide wavelength coverage, from 3400 to 10 400 Å free of second-order effects, of exactly the same region as that of a given galaxy. These observations are analysed applying a methodology designed to obtain accurate elemental abundances of oxygen, sulphur, nitrogen, neon, argon and iron in the ionized gas. Four electron temperatures and one electron density are derived from the observed forbidden line ratios using the five-level atom approximation. For our best objects, errors of 1 per cent in t e ([O iii ]), 3 per cent in t e ([O ii ]) and 5 per cent in t e ([S iii ]) are achieved with a resulting accuracy of 7 per cent in total oxygen abundances, O/H.
The ionization structure of the nebulae can be mapped by the theoretical oxygen and sulphur ionic ratios, on the one side, and the corresponding observed emission line ratios, on the other – the η and η' plots. The combination of both is shown to provide a means to test photoionization model sequences presently applied to derive elemental abundances in H ii galaxies. 相似文献
The ionization structure of the nebulae can be mapped by the theoretical oxygen and sulphur ionic ratios, on the one side, and the corresponding observed emission line ratios, on the other – the η and η' plots. The combination of both is shown to provide a means to test photoionization model sequences presently applied to derive elemental abundances in H ii galaxies. 相似文献
239.
利用22个月的GRACE时变重力场,反演了三峡水库补给水系的水储量变化,并按月给出了数值结果.与水文学同化模型(CPC)的两组比较说明基于GRACE重力的反演结果是合理的.当高斯平均半径为1000 km时,该区总水储量变化的峰谷差为14 cm,其年变化振幅为58 cm,相位为-408天,与CPC模型合成重力数据的反演结果进行比较,其总水储量变化均方差为13 cm,年变化振幅相差01 cm,相位相差10天.为进一步检验GRACE能否监测该区真实水储量变化,还将其反演结果与CPC模型的真实平均结果进行比较,结果发现总体均方差为21 cm,年变化振幅相差17 cm,相位相差93天.因此,第一种比较过高地估计了GRACE监测该区水储量变化的能力,第二种比较则较真实地反映了实际情况,尽管反演结果与水文学的结果差别较大,但仍然显示GRACE能监测该区每月的水储量变化. 相似文献
240.
Felix V. Kaminsky Sergei M. Sablukov Elena A. Belousova Paulo Andreazza Mousseau Tremblay William L. Griffin 《Lithos》2010,114(1-2):16-29
The Juina diamond field, in the 1970–80s, was producing up to 5–6 million carats per year from rich placer deposits, but no economic primary deposits had been found in the area. In 2006–2007, Diagem Inc. discovered a group of diamondiferous kimberlitic pipes within the Chapadão Plateau (Chapadão, or Pandrea cluster), at the head of a drainage system which has produced most of the alluvial diamonds mined in the Juina area. Diamonds from placer deposits and newly discovered kimberlites are identical; they have super-deep origins from the upper-mantle and transition zone. Field observations and petrographic studies have identified crater-facies kimberlitic material at seven separate localities. Kimberlitic material is represented by tuffs, tuffisites and various epiclastic sediments containing chrome spinel, picroilmenite, manganoan ilmenite, zircon and diamond. The diamond grade varies from 0.2–1.8 ct/m3. Chrome spinel has 30–61 wt.% Cr2O3. Picroilmenite contains 6–14 wt.% MgO and 0.2–4 wt.% Cr2O3. Manganoan ilmenite has less than 3 wt.% MgO and 0.38–1.41 wt.% MnO. The 176Hf/177Hf ratio in kimberlitic zircons is 0.028288–0.28295 with εHf = 5.9–8.3, and lies on the average kimberlite trend between depleted mantle and CHUR. The previously known barren and weakly diamondiferous kimberlites in the Juina area have ages of 79–80 Ma. In contrast, zircons from the newly discovered Chapadão kimberlites have a mean 206Pb/238U age of 93.6 ± 0.4 Ma, corresponding to a time of magmatic activity related to the opening of the southern part of the Atlantic Ocean. The most likely mechanism of the origin of kimberlitic magma is super-deep subduction process that initiated partial melting of zones in lower mantle with subsequent ascent of proto-kimberlitic magma. 相似文献