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581.
Trong Vinh Duong Yu-Jun Cui Anh Minh Tang Jean-Claude Dupla Jean Canou Nicolas Calon Alain Robinet 《Acta Geotechnica》2016,11(1):51-59
This paper deals with the resilient behavior of the interlayer soil which is created mainly by the interpenetration of ballast and subgrade soils. The interlayer soil studied was taken from a site in the southeast of France. Large-scale cyclic triaxial tests were carried out at three water contents (w = 4, 6 and 12 %) and three fines contents corresponding to 5, 10 % subgrade added to the natural interlayer soil and 10 % fine particles (<80 μm) removed from the natural interlayer soil. Soil specimens underwent various deviator stresses, and for each deviator stress, a large number of cycles was applied. The effects of deviator stress, number of cycles, water content and fines content on the resilient modulus (M r) were analyzed. It appears that the effects of water content and fines content must be analyzed together because the two effects are closely linked. Under unsaturated conditions, the soil containing high fines content has higher resilient modulus due to the contribution of suction. When the soil approaches the saturated state, it loses its mechanical enhancement with a sharp decrease in resilient modulus. 相似文献
582.
Tianfu Xu Zhaoyun Hou Xiaofeng Jia Nicolas Spycher Zhenjiao Jiang Bo Feng Jin Na Yilong Yuan 《Environmental Earth Sciences》2016,75(24):1502
To reconstruct deep fluid chemical composition and increase the confidence in estimated reservoir temperatures, a more integral geothermometry method was compared to other classical geothermometers. Here, we apply the integrated multicomponent geothermometry (IMG) method using the GeoT code to estimate reservoir temperatures at the Tengchong geothermal field in Southwestern China. Results show reservoir temperatures calculated using the quartz geothermometer are closest to those estimated with the IMG method. The concentrations of Al and Mg, as well as selected minerals for geothermometry computations, are key factors for successfully using the IMG. Using the IMG method together with classical geothermometers can significantly increase confidence in reservoir temperature estimations. The methods presented and simulation program used here may be useful for analysis of other geothermal fields under similar conditions. 相似文献
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585.
Bigg Grant R. Cropper T. E. O’Neill Clare K. Arnold Alex K. Fleming A. H. Marsh R. Ivchenko V. Fournier Nicolas Osborne Mike Stephens Robin 《Natural Hazards》2018,92(2):1113-1136
Natural Hazards - With the polar regions opening up to more marine activities but iceberg numbers more likely to increase than decline as a result of global warming, the risk from icebergs to... 相似文献
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Simon Boivin Mélanie Gretz Bernard Lathuilière Nicolas Olivier Annachiara Bartolini Rossana Martini 《Swiss Journal of Geoscience》2018,111(3):537-548
The end of the Triassic and the Early Jurassic are intervals characterised by profound biotic and environmental changes, accompanied by dramatic decreases in marine fauna diversity. Corals were strongly affected and assemblages underwent a severe reduction; compared with those of the Upper Triassic, the Early Jurassic is traditionally defined as holding a “reef gap”. A Sinemurian coral-microbialites patch reef, located in southern France in the Hérault department (Le Perthus locality), is here described. This bioconstruction developed in a shallow mixed siliciclastic-carbonate inner ramp setting. The reef volume is composed of up to 70% of an intercoral facies mostly microbialites, with subordinated sediments (approximately 20–30% of the intercoral facies). Therefore, the patch reef can be defined as a coral-microbialite bioconstruction, in which microbialites were the main framebuilders. The coral assemblage has low diversity and is dominated by massive to branching colonies of Chondrocoenia clavellata. This highlights the reef diversity after the T/J boundary crisis. The Le Perthus patch reef could have acted as an edge for the dominant currents and probably induced reductions in hydrodynamic energy and sedimentation on one of its sides. Consequently, it could have triggered the growth of small lateral bioconstructions, composed of oysters and microbialites, uniquely on one of its sides. The evolution of the facies shows that the Le Perthus patch reef grew in a shallowing-upward setting accompanied by an increase in siliciclastic inputs. The rate of bioerosion and the faunal assemblage suggest that the bioconstructions could have been developed in a mesotrophic environment. 相似文献
588.
Alexis Nutz Jean‐François Ghienne Mathieu Schuster Raphaël Certain Nicolas Robin Claude Roquin Olivier Raynal Frédéric Bouchette Philippe Duringer Pierre A. Cousineau 《Boreas: An International Journal of Quaternary Research》2014,43(2):309-329
The stratigraphy of the last deglaciation sequence is investigated in Lake Saint‐Jean (Québec Province, Canada) based on 300 km of echo‐sounder two dimensional seismic profiles. The sedimentary archive of this basin is documented from the Late Pleistocene Laurentidian ice‐front recession to the present‐day situation. Ten seismic units have been identified that reflect spatio‐temporal variations in depositional processes characterizing different periods of the Saint‐Jean basin evolution. During the postglacial marine flooding, a high deposition rate of mud settling, from proglacial glacimarine and then prodeltaic plumes in the Laflamme Gulf, produced an extensive, up to 50 m thick mud sheet draping the isostatically depressed marine basin floor. Subsequently, a closing of the water body due to glacio‐isostatic rebound occurred at 8.5 cal. ka BP, drastically modifying the hydrodynamics. Hyperpycnal flows appeared because fresh lake water replaced dense marine water. River sediments were transferred towards the deeper part of the lake into river‐related sediment drifts and confined lobes. The closing of the water body is also marked by the onset of a wind‐driven internal circulation associating coastal hydrodynamics and bottom currents with sedimentary features including shoreface deposits, sediment drifts and a prograding shelf‐type body. The fingerprints of a forced regression are well expressed by mouth‐bar systems and by the shoreface–shelf system, the latter unexpected in such a lacustrine setting. In both cases, a regressive surface of lacustrine erosion (RSLE) has been identified, separating sandy mouth‐bar from glaciomarine to prodeltaic muds, and sandy shoreface wedges from the heterolithic shelf‐type body, respectively. The Lake Saint‐Jean record is an example of a regressive succession driven by a glacio‐isostatic rebound and showing the transition from late‐glacial to post‐glacial depositional systems. 相似文献
589.
Maren Mohler Johannes Bühl Stephen Doherty Siegfried Eggl Vera Theresa Eybl François Farago Aleksandar Jaćimović Lars Hunger Nynne L. B. Lauritsen David Ludena Martina Meisnar Alexander Reissner Nicolas Sarda Benjamin Toullec Meritxell Viñas Tió 《Experimental Astronomy》2010,28(2-3):101-135
A high level of diversity has already been observed among the planets of our own Solar System. As such, one expects extrasolar planets to present a wide range of distinctive features, therefore the characterisation of Earth- and super Earth-like planets is becoming of key importance in scientific research. The Search (Spectropolarimetric Exoplanet AtmospheRe CHaracerisation) mission proposal of this paper represents one possible approach to realising these objectives. The mission goals of Search include the detailed characterisation of a wide variety of exoplanets, ranging from terrestrial planets to gas giants. More specifically, Search will determine atmospheric properties such as cloud coverage, surface pressure and atmospheric composition, and may also be capable of identifying basic surface features. To resolve a planet with a semi major axis of down to 1.4 AU and 30 pc distant Search will have a mirror system consisting of two segments, with elliptical rim, cut out of a parabolic mirror. This will yield an effective diameter of 9 m along one axis. A phase mask coronagraph along with an integral spectrograph will be used to overcome the contrast ratio of star to planet light. Such a mission would provide invaluable data on the diversity present in extrasolar planetary systems and much more could be learned from the similarities and differences compared to our own Solar System. This would allow our theories of planetary formation, atmospheric accretion and evolution to be tested, and our understanding of regions such as the outer limit of the Habitable Zone to be further improved. 相似文献
590.
Alfred S. McEwen Maria E. Banks Kris Becker James W. Bergstrom Edward Bortolini Shane Byrne Frank C. Chuang Ingrid Daubar Donald G. Deardorff W. Alan Delamere Colin M. Dundas Yisrael Espinoza Kathryn E. Fishbaugh Paul E. Geissler Jennifer L. Griffes Virginia C. Gulick Kenneth E. Herkenhoff Windy L. Jaeger Bob Kanefsky Robert King Kelly J. Kolb Alexandra Lefort Kevin W. Lewis Sarah Mattson Michael T. Mellon Moses P. Milazzo Tahirih Motazedian Albert Ortiz Joseph Plassmann Patrick S. Russell Mindi L. Searls Steven W. Squyres Nicolas Thomas Livio L. Tornabene Circe Verba James J. Wray 《Icarus》2010,205(1):2-216
The High Resolution Imaging Science Experiment (HiRISE) on the Mars Reconnaissance Orbiter (MRO) acquired 8 terapixels of data in 9137 images of Mars between October 2006 and December 2008, covering ∼0.55% of the surface. Images are typically 5-6 km wide with 3-color coverage over the central 20% of the swath, and their scales usually range from 25 to 60 cm/pixel. Nine hundred and sixty stereo pairs were acquired and more than 50 digital terrain models (DTMs) completed; these data have led to some of the most significant science results. New methods to measure and correct distortions due to pointing jitter facilitate topographic and change-detection studies at sub-meter scales. Recent results address Noachian bedrock stratigraphy, fluvially deposited fans in craters and in or near Valles Marineris, groundwater flow in fractures and porous media, quasi-periodic layering in polar and non-polar deposits, tectonic history of west Candor Chasma, geometry of clay-rich deposits near and within Mawrth Vallis, dynamics of flood lavas in the Cerberus Palus region, evidence for pyroclastic deposits, columnar jointing in lava flows, recent collapse pits, evidence for water in well-preserved impact craters, newly discovered large rayed craters, and glacial and periglacial processes. Of particular interest are ongoing processes such as those driven by the wind, impact cratering, avalanches of dust and/or frost, relatively bright deposits on steep gullied slopes, and the dynamic seasonal processes over polar regions. HiRISE has acquired hundreds of large images of past, present and potential future landing sites and has contributed to scientific and engineering studies of those sites. Warming the focal-plane electronics prior to imaging has mitigated an instrument anomaly that produces bad data under cold operating conditions. 相似文献