The historical roots of Amazigh and its Arabization Factors in Algeria

The question of the North African Amazighs is slowly emerging as a highly difficult and ideological issue because it is related to the sensitive problem of identity. All historical and scientific aspects need to be studied so that the region gains the recognition it deserves.La cuestión amazigh se está actualmente erigiendo en el norte de África como problemática espinosa y altamente ideologizada vinculada a sensibles conflictos de identidad. Consecuentemente, en este trabajo planteamos un acercamiento histórico y científico integral que permita el reconocimiento cultural que la región merece

Automatic Heart Sounds Segmentation based on the Correlation Coefficients Matrix for Similar Cardiac Cycles Identification

This paper proposes a novel automatic heart sounds segmentation method for deployment in heart valve defect diagnosis. The method is based on the correlation coefficients matrix, calculated between all the heart cycles for similarity identification. Firstly, fundamental heart sounds (S1 and S2) in the presence of extra gallop sounds such as S3 and/or S4 and murmurs are localized with more accuracy. Secondly, two similarity-based filtering approaches (using time and time-frequency domains, respectively) for correlated heart cycles identification are proposed and evaluated in the context of professional clinical auscultated heart sounds of adult patients. Results show the superiority of the novel time-frequency method proposed here particularly in the presence of extra gallop sounds

Transport et cinétique de dépôt des particules en suspension dans un milieu poreux granulaire: étude des mécanismes de rétention des particules

Une étude expérimentale a été menée sur le transport et la rétention de particules en suspension (limon de diamètre modal 6 3m) dans trois colonnes de longueurs 33, 66 et 100 cm remplies de gravier. Les essais de traçage sont réalisés à différentes vitesses d'écoulement par des injections impulsions du mélange particules en suspension / traceur dissous. Un modèle analytique de convection–dispersion avec une cinétique de dépôt de premier ordre a permis d'ajuster les courbes de restitution et de déduire les paramètres hydrodispersifs. Le transport rapide des particules en suspension a été mis en évidence sur toutes les colonnes. La dispersion augmente avec la vitesse porale de façon non linéaire. La cinétique de dépôt augmente jusqu'à une vitesse critique puis diminue. La vitesse critique est fonction de la longueur de la colonne. Ce comportement résulte de la compétition entre les forces hydrodynamiques et gravitationnelles

Effet de la structure sur la migration des particules fines dans un milieu poreux

On présente des résultats d'une étude expérimentale en laboratoire sur l'érosion interne par suffusion d'un milieu poreux soumis à un écoulement. On s'intéresse à l'influence de la structure du milieu poreux sur les processus d'arrachement et de migration des particules fines. Les résultats obtenus montrent clairement l'effet majeur de la structure sur les réponses dans l'espace et dans le temps des milieux testés

Caractérisation d'un milieu poreux colmaté par la méthode du potentiel spontané

Laboratory experiments are performed on the physical clogging of a porous medium by injecting polydispersive suspended particles ranged from 1.7 to 40 μm in a column filled with sand (d50=715 µm). Three suspensions have been injected (2g/l, 3g/l and 5g/l) at constant flow velocity in a saturated porous medium. Hydrodynamic effects on particles deposition and porous medium damage were investigated. Particles retentions are significant at the inlet and decreases with depth which induces the drop of permeability and porosity. The coupling between electric and hydraulic flows is electrokinetic in nature, the second objective of this work is to test the sensitivity of the method of self-potential (SP) and to show the usefulness of this method to understand the controlling parameters of the electrical field associated with the filtration of suspended particles through a porous medium. Electrodes have been used to record the SP signal which detect and quantify the clay particles in the porous medium during injection tests. The variations of the SP signals are linearly correlated to the piezometric level changes. SP signals are directly sensitive to deposition particles distribution, and it is high at the inlet of the column where the deposit is large and decreases with depth. For the test injection with 2g/l the SP signal varies between +16 mv and +13 mv for the test with 3g/l it varies between +12 mv and +8mv and that with 5g/l it varies between - 22mv to-19mv. When the concentration of clay injected in the porous medium increases, the SP signal decreases and changes from a positive sign to a negative sign. SP method confirmed the behavior of the porous medium clogging obtained by the hydraulic measurements. The obtained results show that SP signal is sensitive to clay particles, their immediate passage to the inlet of the column and the amount deposited particles in each section of the porous medium

Étude des mécanismes de transport et la cinétique de dépôt des particules en suspension dans un milieu poreux saturé

LE HAVRE-BU Centrale (763512101) / SudocSudocFranceF

Quantifying the yield stress of bentonite muds mixed with other clays during drilling operations

International audienceIn civil engineering, bentonite-water mixtures, commonly referred to as drilling muds, are intensively used in order to lubricate tools, consolidate walls, and help extracting cuttings during drilling operations. The efficiency of drilling muds in each of these tasks lies in their rheological properties depending mainly on the amount of clay materials. During the field works, drilling muds are mixed with the excavated soil materials (e.g., sand, clay, organic matter) that may change drastically the rheological properties of mixtures. With the aim of understanding better the rheology of field drilling muds mixed with other clays, rheological measurements on monoand binary-clay suspensions were performed using a rotational rheometer equipped with coaxial cylinders, for which the type of clay materials (i.e., bentonite, kaolin and illite), the total clay volume fraction $\varphi_t$ and the bentonite to clay volume ratio $R_b$ were varied. The contribution of this work is twofold: (i) to highlight the major role of $\varphi_t$ and $R_b$ independently on the rheology of binary-clay suspensions and (ii) to provide phenomenological models to quantify the dependency of the yield stress on both $\varphi_t$ and $R_b$ that would be particularly useful for industrial applications