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51.
In this paper, we investigate the characteristics of three-component ground motions recorded during the $M_\text{w}\,5.2$ Val-des-Bois (Québec) earthquake, which occurred on the 23 June 2010. The earthquake is the largest recorded event in eastern Canada within the last decade. The records analyzed were provided by a strong motion monitoring network, comprising accelerometers located at sites with different soil conditions. The two orthogonal horizontal components and one vertical component at each recording station are uncorrelated to determine their principal directions, and the results obtained are used to characterize intensity ratios between the three uncorrelated components. A new hodograph representation is proposed to highlight the correlation between accelerations and displacement trajectories along various time increments at each recording station. The principal components are discussed in light of seismographic data, local site conditions, and trajectories. Time–frequency analyses of the uncorrelated records are also conducted to compare the distribution of spectral amplitudes and frequency content along the three principal components during the shaking. The results of this work shed more light on the characteristics of three-component ground motions from an important Eastern North America earthquake, and could be used to calibrate simulated multicomponent ground motions in this region. 相似文献
52.
Myriam Foucras Jérôme Leclère Cyril Botteron Olivier Julien Christophe Macabiau Pierre-André Farine Bertrand Ekambi 《GPS Solutions》2017,21(2):293-306
In global navigation satellite system (GNSS) receivers, the first signal processing stage is the acquisition, which consists of detecting the received GNSS signals and determining the associated code delay and Doppler frequency by means of correlations with a code and carrier replicas. These codes, as part of the GNSS signal, were chosen to have very good correlation properties without considering the effect of a potential received Doppler frequency. In the literature, it is often admitted that the maximum GPS L1 C/A code cross-correlation is about ?24 dB. We show that this maximum can be as high as ?19.2 dB when considering a Doppler frequency in a typical range of [?5, 5] kHz. We also show the positive impact of the coherent integration time on the cross-correlation and that even a satellite with Doppler outside the frequency search space of a receiver impacts the cross-correlation. In addition, the expression of the correlation is often provided in the continuous time domain, while its implementation is typically made in the discrete domain. It is then legitimate to ask the validity of this approximation. Therefore, the purpose of this research is twofold: First, we discuss typical approximations and evaluate their regions of validity, and second, we provide characteristic values such as maximums and quantiles of the auto- and cross-correlation of the GPS L1 C/A and Galileo E1 OS codes in the presence of Doppler, for frequency ranges up to 50 kHz and for different integration times. 相似文献
53.
Organic photochemical syntheses in the Jovian atmosphere were simulated by irradiating, at 147 nm, gaseous mixtures of methane and ammonia with varying quantities of hydrogen. An excess of H2 did not eliminate organic synthesis but did affect the yields quantitatively and qualitatively. 相似文献
54.
Cyril Aubaud Marc M. Hirschmann Anthony C. Withers Richard L. Hervig 《Contributions to Mineralogy and Petrology》2008,156(5):607-625
To understand partitioning of hydrogen between hydrous basaltic and andesitic liquids and coexisting clinopyroxene and garnet,
experiments using a mid-ocean ridge basalt (MORB) + 6 wt.% H2O were conducted at 3 GPa and 1,150–1,325°C. These included both isothermal and controlled cooling rate crystallization experiments,
as crystals from the former were too small for ion microprobe (SIMS) analyses. Three runs at lower bulk water content are
also reported. H2O was measured in minerals by SIMS and in glasses by SIMS, Fourier Transform infrared spectroscopy (FTIR), and from oxide
totals of electron microprobe (EMP) analyses. At 3 GPa, the liquidus for MORB with 6 wt.% H2O is between 1,300 and 1,325°C. In the temperature interval investigated, the melt proportion varies from 100 to 45% and the
modes of garnet and clinopyroxene are nearly equal. Liquid composition varies from basaltic to andesitic. The crystallization
experiments starting from above the liquidus failed to nucleate garnets, but those starting from below the liquidus crystallized
both garnet and clinopyroxene. SIMS analyses of glasses with >7 wt.% H2O yield spuriously low concentrations, perhaps owing to hydrogen degassing in the ultra-high vacuum of the ion microprobe
sample chamber. FTIR and EMP analyses show that the glasses have 3.4 to 11.9 wt.% water, whilst SIMS analyses indicate that
clinopyroxenes have 1,340–2,330 ppm and garnets have 98–209 ppm H2O. D
H
cpx−gt is 11 ± 3, D
H
cpx−melt is 0.023 ± 0.005 and D
H
gt−melt is 0.0018 ± 0.0006. Most garnet/melt pairs have low values of D
H
gt−melt, but D
H
gt−melt increases with TiO2 in the garnet. As also found by previous studies, values of D
H
cpx−melt increase with Al2O3 of the crystal. For garnet pyroxenite, estimated values of D
H
pyroxenite−melt decrease from 0.015 at 2.5 GPa to 0.0089 at 5 GPa. Hydration will increase the depth interval between pyroxenite and peridotite
solidi for mantle upwelling beneath ridges or oceanic islands. This is partly because the greater pyroxene/olivine ratio in
pyroxenite will tend to enhance the H2O concentration of pyroxenite, assuming that neighboring pyroxenite and peridotite bodies have similar H2O in their pyroxenes.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
55.
56.
Cyril G. Tuckfield 《地球表面变化过程与地形》1986,11(1):23-40
Dells in the New Forest are described as amphitheatre-shaped hollows, perched on valley sides, sometimes singly, in other places in groups tributary to small dry valleys. They have steep rear walls and sides, flatfish floors, and convex lips, usually without any water-worn channels. The slopes on which they occur, cut in Eocene sands and clays, have been subjected to solifluction, and this has produced wide gently sloping terraces at the foot of the hillside. Superficial deposits within the New Forest dells are divided into two groups by process: a lower head of fragmented flints in a sandy or clayey matrix, assigned to Zone III; overlying colluvial deposits including slumped material and slope wash, dated by reference to a buried soil to Zone VIIa. Although scoured by solifluction, other processes probably account for the initial formation of the hollows, and nivation is suggested. The dells are compared with the chalk coombes of southern England and the dellen of European and other writers. A possible chronology is suggested for the New Forest dells. 相似文献
57.
A method of extraction for amino acids from soils and sediments involving superheated water has been investigated. About 75–97 per cent of the amino acids contained in four soils of a soil profile from Illinois were extracted by this method. Deep penetration of water into soil aggregates and partial hydrolysis of peptide bonds during this extraction by water at high temperature are likely mechanisms responsible for the release of amino acids from samples. This extraction method does not require subsequent desalting treatments when analyses are carried out with an ion-exchange amino acid analyzer. 相似文献
58.
Dutheil Cyril Menkes C. Lengaigne M. Vialard J. Peltier A. Bador M. Petit X. 《Climate Dynamics》2021,56(1-2):87-108
Climate Dynamics - Global climate models projections indicate no clear future rainfall changes over the Southwestern Pacific islands in response to anthropogenic forcing. Yet, these models have low... 相似文献
59.
In this paper the influence of the nonlinear behaviour of the primary structure on floor spectra is investigated by means of simple models. The general trends of floor spectra for different types of nonlinear behaviour of one degree of freedom (1DOF) primary structure are shown and we point out their common futures and their differences. A special attention is given to the cases of elastoplastic and nonlinear elastic behaviours and methods to determine an equivalent linear oscillator are proposed. The properties (frequency and damping) of this equivalent linear oscillator are quite different from the properties of equivalent linear oscillators commonly considered in practice. In particular, in the case of elastoplastic behaviour, there is no frequency shift and damping is smaller than assumed by other methods commonly used. In the case of nonlinear elastic behaviour, the concept of an equivalent frequency which is a random variable is used. Finally, a design floor spectrum of primary structures, exhibiting energy dissipating nonlinear behaviour is proposed. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
60.
Laurent Oscar Couzinié Simon Zeh Armin Vanderhaeghe Olivier Moyen Jean-François Villaros Arnaud Gardien Véronique Chelle-Michou Cyril 《International Journal of Earth Sciences》2017,106(2):421-451
International Journal of Earth Sciences - The late stages of the Variscan orogeny are characterized by middle to lower crustal melting and intrusion of voluminous granitoids throughout the belt,... 相似文献