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991.
992.
Effects of Drying on the Low-Frequency Electrical Properties of Tournemire Argillites 总被引:1,自引:0,他引:1
Philippe Cosenza Ahmad Ghorbani Nicolas Florsch André Revil 《Pure and Applied Geophysics》2007,164(10):2043-2066
Nearly water-saturated argillite samples (initial water content near 3.4 wt%) were cored from an undisturbed area of an underground
facility of the French Institute for Radioprotection and Nuclear Safety (IRSN), located at Tournemire (Aveyron, France). These
samples were subjected to the following desiccation path: (a) A desaturation phase during which the samples were dried at
ambient temperature conditions, relative humidity equal to 43% in average and (b) a heating phase during which the same samples
were heated at four temperature levels from 70°C up to 105°C. During both phases, the low-frequency complex resistivity (0.18Hz–12
kHz) was recorded by a four-electrode device. The amplitude of the complex resistivity was extremely sensitive to water content
change. At the end of the isotherm desaturation phase, it was multiplied by a factor of 3 to 5. During the heating phase,
the resistivity increased by more than two orders of magnitude compared to the initial state. The percentage of Frequency
Effect shows a low sensitivity to water content changes during the desaturation stage while it increased by two orders of
magnitude during the heating phase. This result confirms that low-frequency spectral signature is extremely sensitive to textural
changes (i.e., thermal-induced microcracking in this case) that occurred during heating. Moreover, the complex resistivity
of the samples shows a strong anisotropy (a ratio of 10 between both amplitudes measured in the perpendicular directions).
The classical Cole-Cole model cannot be used to fit the experimental data obtained in the heating phase. A generalized formulation
of this model is required and was successfully applied to represent the complex resistivity data. 相似文献
993.
Philippe Drobinski Cyrille Flamant Jan Dusek Pierre H. Flamant Jacques Pelon 《Boundary-Layer Meteorology》2001,98(3):497-515
A hydraulic jump has been observed with the airborne backscatter lidar LEANDRE 1 (Lidar embarqué pour l'Etude des Aérosols, des Nuages, des interactions Dynamique-Rayonnement etdu cycle de l'Eau) at the top of the atmospheric boundary layer (ABL) during a Tramontane event in the framework of the Pyréneés experiment. An analytical fluid mechanics model is used to interpret lidar observations in connection with in situ measurements andto study the sensitivity of the hydraulic jump triggering to the boundary conditions. This model, which generalizes the reduced-gravity shallow-water theory for two-dimensional stratified flows over a topograpy, is diagnostic (i.e., the reduced gravity g' = g
v
v is prescribed) and uses boundary conditions defined in terms of Riemann invariants. Using inflow and outflow boundary conditions as well as the reduced gravity prescribed from in situ measurements, the model is able to diagnose the presence of a hydraulic jump at the location suspected from the lidar observations. The wind speed, ABL height and Froude number derived from the model are in good agreement with the observations (within about 20–30%). 相似文献
994.
Elisa Sacchi Jean-Luc Michelot Helmut Pitsch Philippe Lalieux Jean-François Aranyossy 《Hydrogeology Journal》2001,9(1):17-33
This paper summarises the results of a comprehensive critical review, initiated by the OECD/NEA "Clay Club," of the extraction
techniques available to obtain water and solutes from argillaceous rocks. The paper focuses on the mechanisms involved in
the extraction processes, the consequences on the isotopic and chemical composition of the extracted pore water and the attempts
made to reconstruct its original composition. Finally, it provides some examples of reliable techniques and information, as
a function of the purpose of the geochemical study.
Electronic Publication 相似文献
995.
Jaouher Kerrou Philippe Renard Fabien Cornaton Pierre Perrochet 《Hydrogeology Journal》2013,21(2):425-440
A stochastic study of long-term forecasts of seawater intrusion with an application to the Korba aquifer (Tunisia) is presented. Firstly, a geostatistical model of the exploitation rates was constructed, based on a multi-linear regression model combining incomplete direct data and exhaustive secondary information. Then, a new method was designed and used to construct a geostatistical model of the hydraulic conductivity field by combining lithological information and data from hydraulic tests. Secondly, the effects of the uncertainties associated with the pumping rates and the hydraulic conductivity field on the 3D density-dependent transient model were analysed separately and then jointly. The forecasts of the impacts of two different management scenarios on seawater intrusion in the year 2048 were performed by means of Monte Carlo simulations, accounting for uncertainties in the input parameters as well as possible changes of the boundary conditions. Combining primary and secondary data allowed maps of pumping rates and the hydraulic conductivity field to be constructed, despite a lack of direct data. The results of the stochastic long-term forecasts showed that, most probably, the Korba aquifer will be subject to important losses in terms of regional groundwater resources. 相似文献
996.
Florian Perez Claude Mügler Philippe Jean-Baptiste Jean Luc Charlou 《Computational Geosciences》2013,17(2):217-237
We present a new numerical tool developed in the Cast3M software framework to model hydrothermal circulation. Thermodynamic properties of one-phase pure water are calculated from the International Association for the Properties of Water and Steam formulation. This new numerical tool is validated on several test cases of convection in closed-top and open-top boxes. Simulations of hydrothermal circulation in a homogeneous-permeability porous medium also give results in good agreement with already published simulations. This new numerical tool is used to construct a geometric and physical conceptual model of the Rainbow vent site at 36°14′N on the Mid-Atlantic Ridge. Several configurations are discussed, showing that high temperatures and high mass fluxes measured at the Rainbow site cannot be modeled with hydrothermal circulation in a homogeneous-permeability porous medium. These high values require the presence of a fault or a preferential pathway right below the venting site. We propose and discuss a two-dimensional single-pass model that allows us to simulate both high temperatures and high mass fluxes. This modeling of the hydrothermal circulation at the Rainbow site constitutes the first but necessary step to understand the origin of high concentrations of hydrogen issued from this ultramafic-hosted vent field. 相似文献
997.
We present a dynamo mechanism arising from the presence of barotropically unstable zonal jet currents in a rotating spherical shell. The shear instability of the zonal flow develops in the form of a global Rossby mode, whose azimuthal wavenumber depends on the width of the zonal jets. We obtain self-sustained magnetic fields at magnetic Reynolds numbers greater than 103. We show that the propagation of the Rossby waves is crucial for dynamo action. The amplitude of the axisymmetric poloidal magnetic field depends on the wavenumber of the Rossby mode, and hence on the width of the zonal jets. We discuss the plausibility of this dynamo mechanism for generating the magnetic field of the giant planets. Our results suggest a possible link between the topology of the magnetic field and the profile of the zonal winds observed at the surface of the giant planets. For narrow Jupiter-like jets, the poloidal magnetic field is dominated by an axial dipole whereas for wide Neptune-like jets, the axisymmetric poloidal field is weak. 相似文献
998.
Philippe Lamy Pierre Vernazza Joel Poncy Vincent Martinot Emmanuel Hinglais Elisabet Canalias Jim Bell Dale Cruikshank Olivier Groussin Joern Helbert Francesco Marzari Alessandro Morbidelli Pascal Rosenblatt Holger Sierks 《Experimental Astronomy》2012,33(2-3):685-721
In our present understanding of the Solar System, small bodies (asteroids, Jupiter Trojans, comets and TNOs) are the most direct remnants of the original building blocks that formed the planets. Jupiter Trojan and Hilda asteroids are small primitive bodies located beyond the ‘snow line’, around respectively the L4 and L5 Lagrange points of Jupiter at ~5.2?AU (Trojans) and in the 2:3 mean-motion resonance with Jupiter near 3.9?AU (Hildas). They are at the crux of several outstanding and still conflicting issues regarding the formation and evolution of the Solar System. They hold the potential to unlock the answers to fundamental questions about planetary migration, the late heavy bombardment, the formation of the Jovian system, the origin and evolution of trans-neptunian objects, and the delivery of water and organics to the inner planets. The proposed Trojans’ Odyssey mission is envisioned as a reconnaissance, multiple flyby mission aimed at visiting several objects, typically five Trojans and one Hilda. It will attempt exploring both large and small objects and sampling those with any known differences in photometric properties. The orbital strategy consists in a direct trajectory to one of the Trojan swarms. By carefully choosing the aphelion of the orbit (typically 5.3?AU), the trajectory will offer a long arc in the swarm thus maximizing the number of flybys. Initial gravity assists from Venus and Earth will help reducing the cruise time as well as the ΔV needed for injection thus offering enough capacity to navigate among Trojans. This solution further opens the unique possibility to flyby a Hilda asteroid when leaving the Trojan swarm. During the cruise phase, a Main Belt Asteroid could be targeted if requiring a modest ΔV. The specific science objectives of the mission will be best achieved with a payload that will perform high-resolution panchromatic and multispectral imaging, thermal-infrared imaging/ radiometry, near- and mid-infrared spectroscopy, and radio science/mass determination. The total mass of the payload amounts to 50?kg (including margins). The spacecraft is in the class of Mars-Express or a down-scaled version of Jupiter Ganymede Orbiter. It will have a dry mass of 1200?kg, a total mass at launch of 3070?kg and a ΔV capability of 700?m/s (after having reached the first Trojan) and can be launched by a Soyuz rocket. The mission operations concept (ground segment) and science operations are typical of a planetary mission as successfully implemented by ESA during, for instance, the recent flybys of Main Belt asteroids Steins and Lutetia. 相似文献
999.
Joke BELZA Steven GODERIS Eddy KEPPENS Frank VANHAECKE Philippe CLAEYS 《Meteoritics & planetary science》2012,47(3):400-413
Abstract– To better constrain the emplacement mechanism of the so‐called “mega‐block zone,” a structurally complex unit of target rocks within the Chicxulub impact structure, the stratigraphic coherence of this zone is tested using its strontium isotopic composition. Forty‐eight samples across the 616 m sequence of deformed Cretaceous rocks in the lower part of the Yaxcopoil‐1 core, drilled by ICDP in 2002, were analyzed for their 87Sr/86Sr isotope ratio. The oceanic anoxic event 2 (OAE2 event), located near the base of the core forms the only stratigraphic anchor point. From this point upward to approximately 1050 m depth, the 87Sr/86Sr trend shows small oscillations, between approximately 0.7074 and 0.7073, characteristic of Cenomanian to Santonian values. This is followed by an increase to approximately 0.7075, similar to the one reported in the seawater strontium curve during the Campanian. Scattered Sr isotope ratios are attributed to local diagenetic effects, such as those expected from the possible presence of hot, impact‐induced dikes and hydrothermal fluid flow, originating from the thick central melt sheet. The absence of Upper Maastrichtian Sr isotope values may result from the removal of upper target lithologies during the impact cratering process. Based on these results, the displaced Cretaceous sequence in Yax‐1 appears to have preserved its stratigraphic coherence. During the modification stage, it probably moved as a whole into the annular basin during collapse of the crater wall, thereby breaking up into discrete units along previously weakened detachment zones. This model is consistent with the emplacement mechanism postulated by Kenkmann et al. (2004) . 相似文献
1000.
Aretouyap Zakari Kemgang Franck Eitel G Domra Janvier K Bisso Dieudonne Njandjock Philippe N 《Natural Hazards》2021,109(2):1589-1602
Natural Hazards - Remote sensing was used to visualize the West region with the purpose of investigating recent natural hazards observed in this area. Various approaches used based on... 相似文献