The Effect of pH on Electro-osmotic Flow in Argillaceous Rocks     

Mohamed Younes Ahmed  Said Taibi  Hanène Souli  Jean-Marie Fleureau 《Geotechnical and Geological Engineering》2013,31(4):1335-1348

The use of electro-osmosis in geotechnical engineering has been considered since 1930. Its application has been tested in several sectors like the fight against rising damp in porous materials, the consolidation of soils as well as the remediation of the soils contaminated by oil and heavy metals, etc. The paper presents an experimental study of the electrokinetic phenomena resulting from the application of an electric field to argillaceous sandstones. The electroosmotic tests required the development of a completely new experimental device composed of a confining cell, of a system of measurement and control of the pH of the electrolyte near the electrodes, of a system of control and measurement of the voltage and current at the edges of the sample, and of a system of measurement of inlet (anodic) and outlet (cathodic) flows. Various boundary conditions are considered with and without control of pH. In addition, a micro structural modelling of the electrokinetic phenomena makes it possible to quantify the electro osmotic conductivity with a good agreement with experiments.  相似文献   

A thermo‐hydro‐mechanical model for unsaturated soils based on the effective stress concept     

Matthieu Dumont  Said Taibi  Jean‐Marie Fleureau  Nabil Abou‐Bekr  Abdelghani Saouab 《国际地质力学数值与分析法杂志》2011,35(12):1299-1317

A simple thermo‐hydro‐mechanical (THM) constitutive model for unsaturated soils is described. The effective stress concept is extended to unsaturated soils with the introduction of a capillary stress. This capillary stress is based on a microstructural model and calculated from attraction forces due to water menisci. The effect of desaturation and the thermal softening phenomenon are modelled with a minimal number of material parameters and based on existing models. THM process is qualitatively and quantitatively modelled by using experimental data and previous work to show the application of the model, including a drying path under mechanical stress with transition between saturated and unsaturated states, a heating path under constant suction and a deviatoric path with imposed suction and temperature. The results show that the present model can simulate the THM behaviour in unsaturated soils in a satisfactory way. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Distribution des terres rares dans les fractions de sediments et nodules de Fe et Mn associes en l'ocean Indien     

Said Tlig 《Marine Geology》1982,50(3):257-274

The REE distribution in size fractions of sediments and associated ferromanganese nodules from the Indian Ocean was studied. Bulk-sample patterns of sediments result from the combination of coarsest fractions depleted in Ce and fine fractions enriched in Ce. Ce depletion of the coarsest fractions is related to biogenic silica; on the contrary, REE distribution patterns of fine fractions are closely similar to those of associated ferromanganese nodules. The Ce excess in fine fractions is probably of continental origin, but it could also be derived from submarine weathering of volcanic glass or related to Ce oxydation in the marine environment. In fine fractions Ce is probably in its tetravalent state, hence it can easily be scavenged by fine clays and oxyhydroxydes. Trivalent REE can be incorporated in nodules, partly by occlusion of fine clays or oxyhydroxydes and partly by surface to surface transfer as was proposed by Ehrlich (1968). Comparison between REE patterns of fine-sized fractions, nodules and seawater also supported adsorption as a possible mechanism governing the incorporation of REE of sediments and nodules from seawater. Light REE are probably incorporated as oxyhydroxyde complexes, whereas heavy REE are markedly fractionated with increasing atomic number. This fractionation reflects the complexed form of the heavy REE in seawater.  相似文献   

Aircraft measurements of sea surface conditions and their relationship to marine boundary-layer dynamics     

Aimé Druilhet  Pierre Durand  Alberte Fischer  Frédérique Said 《Boundary-Layer Meteorology》1990,52(4):397-414

Through simultaneous measurements, it is possible to demonstrate the relation between sea swell and surface temperature as measured by a thermoradiometer onboard an aircraft. Thermodynamic measurements made on board the aircraft enable analysis of the interaction between swell and surface marine layer dynamics. The cospectral functions of vertical turbulent transfer for sensible and latent heat indicate large-scale dynamic structures which would seem to be initiated by inhomogeneities in the humidity field. A cross-spectral examination of temperature and humidity produces a structure that is common to both parameters and is caused by swell propagation. The data used here were collected during the TOSCANE-T experiment, whose aim was to validate remote sensing scatterometer techniques, by means of an instrumented aircraft designed for atmospheric research.  相似文献   

Wake II model for hydrodynamic forces on marine pipelines including waves and currents     

Said R. Sabag  Billy L. Edge  Iwan Soedigdo 《Ocean Engineering》2000,27(12)

The Wake II model for the determination of the hydrodynamic forces on marine pipelines is extended to include currents and waves. There are two main differences between the Wake II and the traditional model. First, in the Wake II model the velocity is modified to include the pipe's encounter with the wake flow when the velocity reverses. Second, the model uses time dependent drag and lift coefficients. The flow field is assumed to be the linear superposition of regular waves and uniform current and is treated as wave only but in two different phases. The model requires eight empirical parameters that are obtained from comparisons with field data for various Keulegan–Carpenter numbers and current to wave ratios. The effective velocity and the force predictions are compared with field data from Exxon Production Research Company and with the conventional model. The model gives satisfactory results and predicts lift forces that in shape, magnitude and phase relative to the velocity are in very close agreement with measured forces. For the horizontal forces the results are very accurate. A substantial improvement is obtained over the predictions with the conventional model. This work is applicable to the design of submarine pipelines laying on the sea bottom in water depths where waves or waves and currents contribute to the hydrodynamic forces.  相似文献   

Identification of cytochrome P450 1B-like sequences in two teleost fish species (scup, Stenotomus chrysops and plaice, Pleuronectes platessa) and in a cetacean (striped dolphin, Stenella coeruleoalba).     

C A Godard  M J Leaver  M R Said  R L Dickerson  S George  J J Stegeman 《Marine environmental research》2000,50(1-5):7-10

The cytochromes P450 (CYP) constitute a multigene family of enzymes playing a critical role in the oxidation of many endogenous and xenobiotic substrates. The CYP1 family is of particular interest in environmental toxicology because its members are dominant in the metabolism of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and aryl amines. Three members of the CYP1 family, CYP1A1, CYP1A2, and CYP1B1, have been identified in mammals. We report here on the identification and cloning of cytochrome P4501B-like sequences from two teleost fish species and a marine mammal. Sequences clustering with CYP1B1 in phylogenetic analysis were obtained from liver cDNA of scup (Stenotomus chrysops), genomic DNA of plaice (Pleuronectes platessa), and liver cDNA of striped dolphin (Stenella coeruleoalba).  相似文献   

Effect of temperature on the physical precursors of rock block failure     

Kamel Baddari  Anatoly D. Frolov  Victor Tourtchine  Said Makdeche  Fayçal Rahmoune 《Acta Geophysica》2012,60(4):1007-1029

The influence of temperature (25–400 °C) on the variations of mechanical, acoustic, electric and electromagnetic precursors of rock failure has been shown experimentally. The most significant variations were detected in the principal parameters of the acoustic and electromagnetic emissions whose impulse energy underwent a fast growth. However, the general character of hierarchical evolution stages of micro and macrofailure was practically unchanged. This has been confirmed by the so-called concentration parameter of rupture, which is theoretically calculated and checked in experiments; its space-time variations preceding the occurrence and progression of macrofailure are slightly depending on the rock temperature effect. This has been shown through the convolution of some physical precursors in a complex parameter whose variation showed an approaching of macrofailure, which remains slightly influenced by changes in temperature. Our results are interpreted in relation to physics of superficial earthquakes and precursors.  相似文献   

Rupture of an evaporating liquid bridge between two grains     

Boleslaw Mielniczuk  Moulay Said El Youssoufi  Laurent Sabatier  Tomasz Hueckel 《Acta Geophysica》2014,62(5):1087-1108

The study examines rupture of evaporating liquid bridges between two glass spheres. Evolution of the bridge profile has been recorded with the use of high-speed camera. Geometrical characteristics of the bridge were then used to calculate evolution of the variables during the process: Laplace pressure, capillary force, and surface tension force. For the purpose of reference, the bridge evolution is followed also during kinematic extension. During both processes the diameter of the neck decreases, with an acceleration of about 1–2 ms before the rupture. Two distinct rupture modes are observed, depending on the bridge aspect ratio. After the rupture, the mass of liquid splits, forming two separate oscillating drops attached to the spheres, and a suspended satellite droplet. Just before the rupture, an increasing repulsive Laplace pressure, and decreasing negative surface tension force develop. Capillary force follows the trend of the surface tension force, with an accelerating decline. Duration of the whole process and liquid mass stabilization is from 10 to 60 ms.  相似文献   

Some Probabilistic and Statistical Properties of the Seismic Regime of Zemmouri (Algeria) Seismoactive Zone   总被引：1，自引：1，他引：0  

Kamel Baddari  Fouzi Bellalem  Ibtihel Baddari  Said Makdeche 《Acta Geophysica》2016,64(5):1275-1310

Statistical tests have been used to adjust the Zemmouri seismic data using a distribution function. The Pareto law has been used and the probabilities of various expected earthquakes were computed. A mathematical expression giving the quantiles was established. The extreme values limiting law confirmed the accuracy of the adjustment method. Using the moment magnitude scale, a probabilistic model was made to predict the occurrences of strong earthquakes. The seismic structure has been characterized by the slope of the recurrence plot γ, fractal dimension D, concentration parameter K_sr, Hurst exponents H_r and H_t. The values of D, γ, K_sr, H_r, and H_t diminished many months before the principal seismic shock (M = 6.9) of the studied seismoactive zone has occurred. Three stages of the deformation of the geophysical medium are manifested in the variation of the coefficient G% of the clustering of minor seismic events.  相似文献   

Attenuation of ground vibrations due to different technical sources     

L. Auersch  S. Said 《地震工程与工程振动(英文版)》2010,9(3):337-344

The attenuation of technically induced surface waves is studied theoretically and experimentally.In this paper, nineteen measurements of ground vibrations induced by eight different technical sources including road and rail traffic, vibratory and impulsive construction work or pile driving, explosions, hammer impulses and mass drops are described, and it is shown that the technically induced ground vibrations exhibit a power-law attenuation v～r-q where the exponents q are in the range of 0.5 to 2.0 and depend on the source types.Comparisons performed demonstrate that the measured exponents are considerably higher than theoretically expected.Some potential effects on ground vibration attenuation are theoretically analyzed.The most important effect is due to the material or scattering damping.Each frequency component is attenuated exponentially as exp(-kr), but for a broad-band excitation, the sum of the exponential laws also yields a power law but with a high exponent.Additional effects are discussed, for example the dispersion of the Rayleigh wave due to soil layering, which yields an additional exponent of 0.5 in cases of impulsive loading.  相似文献