Évaluation de la qualité des eaux souterraines pour l’utilisation dans l’eau potable et l’agriculture : plaine de Tadla, Maroc

La plaine de Tadla fait partie du bassin de l’oued Oum Erbia situé au centre du Maroc. Ses ressources en eau souterraine sont développées pour l’approvisionnement en eau potable, industrielle et agricole. Afind'évaluer la qualité des eaux souterraines dans la zone d’ d'étude, 25 échantillons d'eau souterraines ont été prélevés et différents paramètres ont été analysés sur le plan physico-chimique et bactériologique:température, conductivité électrique, pH, TDS, Na+, K+, Ca2+, Mg2+, Cl-, HCO-3, SO2-4, NO-3, NH+4, FeT, streptocoques fécaux, coliformes fécaux et coliformes totaux. L'indice chimique tel que le coefficient d’absorption du sodium (SAR) et l'indice de perméabilité (IP) ont également été déterminés. Les résultats obtenus montrent que les eaux souterraines du bassin sont généralement dure à très à dure. Les concentrations sont classées comme suit : Na+ > Ca2+ > Mg2+ > K+ et Cl- > HCO3- > SO42- > NO-3. Les faciès chimiques trouvés sont le bicarbonaté calcique et le Chloruré sodique avec une prédominance de ce dernier. La qualité des eaux souterraines est liée à la lithologie du secteur. Les valeurs de l'indice de saturation (calculés par le programme PHREEQC) montre que presque tous les échantillons d'eau sont saturés à sous-saturés en carbonate et sous saturés en sulfate. Le rapport d’adsorption du sodium (SAR)nous a permis de qualifier les eaux souterraines destinées à l’irrigation. L’analyse hydrochimique a montré la mauvaise qualité des eaux se traduisant par des valeurs importantes en chlorures, en nitrites et nitrates.Ainsi que la contamination de tous les puits par les germes de la  contamination fécale. Il ressort de cette analyse que les eaux souterraines sont chimiquement non appropriées à la consommation humaine et auxusages agricoles.Mots-clés : plaine de Tadla, hydrochimie, qualité des eaux souterraines, hydrogéologie, type d’eau

An optimized deep learning model for optical character recognition applications

The convolutional neural networks (CNN) are among the most utilized neural networks in various applications, including deep learning. In recent years, the continuing extension of CNN into increasingly complicated domains has made its training process more difficult. Thus, researchers adopted optimized hybrid algorithms to address this problem. In this work, a novel chaotic black hole algorithm-based approach was created for the training of CNN to optimize its performance via avoidance of entrapment in the local minima. The logistic chaotic map was used to initialize the population instead of using the uniform distribution. The proposed training algorithm was developed based on a specific benchmark problem for optical character recognition applications; the proposed method was evaluated for performance in terms of computational accuracy, convergence analysis, and cost

Lower bounds for nodal sets of Dirichlet and Neumann eigenfunctions

Let \phi\ be a Dirichlet or Neumann eigenfunction of the Laplace-Beltrami operator on a compact Riemannian manifold with boundary. We prove lower bounds for the size of the nodal set {\phi=0}.Comment: 7 page

Delineating and mapping riparian areas for ecosystem service assessment

Riparian buffers, the interface between terrestrial and freshwater ecosystems, have the potential to protect water bodies from land-based pollution, and also for enhancing the delivery of a range of ecosystem services. The UK currently has no defined optimal width or maximum extent of riparian buffers for specific ecosystem services. Here, we present the first study, which attempts to (a) compare and critique different riparian buffer delineation methods and (b) investigate how ecological processes, for example, pollutant removal, nutrient cycling, and water temperature regulation, are affected spatially by proximity to the river and also within a riparian buffer zone. Our results have led to the development of new concepts for riparian delineation based on ecosystem service-specific scenarios. Results from our study suggest that choice of delineation method will influence not only the total area of potential riparian buffers but also the proportion of land cover types included, which in turn will determine their main ecosystem provision. Thus, for some ecological processes (e.g., pollutant removal), a fixed-distance approach will preserve and protect its ecosystem function, whereas for processes such as denitrification, a variable-width buffer will reflect better riparian spatial variability maximizing its ecological value. In summary, riparian delineation within UK habitats should be specific to the particular ecosystem service(s) of interest (e.g., uptake of nutrients and shading), and the effectiveness of the buffer should be ground-truthed to ensure the greatest level of protection

Time Protection: the Missing OS Abstraction

Timing channels enable data leakage that threatens the security of computer systems, from cloud platforms to smartphones and browsers executing untrusted third-party code. Preventing unauthorised information flow is a core duty of the operating system, however, present OSes are unable to prevent timing channels. We argue that OSes must provide time protection in addition to the established memory protection. We examine the requirements of time protection, present a design and its implementation in the seL4 microkernel, and evaluate its efficacy as well as performance overhead on Arm and x86 processors