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31.
Résumé L'étude des bassins côtiers de Sfax et de la Djeffara de Gabès Nord, basée sur l'interprétation des données hydrochimiques (éléments majeurs) et isotopiques (18O, 2H et 14C), a permis une meilleure compréhension du fonctionnement hydrodynamique de l'aquifère Miocène le long de la frange côtière. En effet, d'après les données géochimiques, apparaît la présence de deux types de faciès chimiques: chloruré sodique dans le bassin de Sfax et mixte à chloruré sodique dans le bassin de Gabès Nord. Cette transition d'un faciès à un autre souligne la variabilité des origines de minéralisation des eaux. L'utilisation des outils isotopiques a permis l'identification d'une eau relativement ancienne à l'exception de quelques poches de recharge récente matérialisées à partir du relief de Zemlet El Beida en amont du bassin de Gabès Nord. Ceci a été vérifié par les fortes activités en14C des eaux dans cette région. Par conséquent, on peut noter que le passage du Sud au Nord le long de la côte est marqué par une grande variation latérale de lithologie et d'épaisseur de la formation aquifère, soulignant ainsi l'indépendance de chacun des deux réservoirs de Sfax et de la Djeffara de Gabès en absence de toute continuité hydrodynamique entre les deux bassins. Editeur Z.W. Kundzewicz; Editeur associé S. Faye Citation Ben Cheikh, N., Zouari, K., et Abidi, B., 2012. Application des outils chimiques et isotopiques à l'étude de la relation hydrodynamique entre les aquifères profonds de Sfax et de la Djeffara de Gabès Nord (Sud-Est tunisien). Hydrological Sciences Journal, 57 (8), 1662–1671. 相似文献
32.
Weak ion-acoustic double-layers (IA-DLs) in a two-component plasma are investigated in the context of the nonextensive statistics
proposed by Tsallis. Due to the entropic index q, our plasma model can admit compressive as well as rarefactive IA-DLs. It is shown that the values
\frac53 < q < 3\frac{5}{3}q-parameters for the existence of small-DLs. As long as the Mach number M is less than ∼1.42, the only admissible q-values which may lead to IA-DLs are all positive. For −1<q<1 (1<q<5/3), the effect of increasing q is to lower (to shift towards higher values) the critical Mach number M
cr above which only compressive IA-DL are admitted. Beyond q=3, only compressive small-amplitude ion-acoustic double layers are observed. Furthermore, due to the flexibility of the q-parameter, the obtained results bring a possibility to deal with small-DLs with relatively high Mach numbers. Our investigation
may be of wide relevance to astronomers and space scientists working on interstellar plasmas. 相似文献
33.
Yamina Ait Meziane Essaid Djakab Djillali Benouar Ibrahim Ilhan Esat 《Natural Hazards》2012,62(2):189-206
The aim of this study is the comparison between the fundamental periods identified experimentally and those calculated using the formulas given in the Algerian Seismic Code (RPA 99) for vulnerability assessment and for experimental data collection of selected sample of old buildings. The results obtained for vulnerability assessment will then be extrapolated to buildings of the same typology built during the 1949 to 1954 period in the northern part of Algeria. From 1949 to 1954, the reinforced concrete constructions in Algeria were built before the first generation of the Algerian Seismic Code. These buildings being old are certainly weakened by the occupancy activities and seismic event loads. Hence, the evaluation of their vulnerability with respect to the regional seismic hazard requires the knowledge of their structure on a site capacity. The empirical formulas to calculate the fundamental period of a building are based on the Algerian Earthquake Code (RPA 99) .These formulas consider only the geometrical dimension (length, width and height) and the structural design of the buildings. The fundamental periods of vibration of twenty-two buildings, located in Algiers, calculated using the empirical formulas given in the RPA 99 are lower than those identified experimentally. A question then rises, do these tested buildings present any damage or not? As five of these buildings were tested before the 21 May 2003 earthquake, the experimental testing highlighted a decrease in the fundamental frequency which means that these buildings are damaged. Hence, for vulnerability assessment, the empirical formulas given in the Algerian Seismic Code (RPA 99) may not be appropriate for vulnerability assessment of the old buildings built during the 1949 to 1954 period. 相似文献
34.
Muhammad Malik Nauman Murtuza Mehdi Asif Iqbal Muhammad Saifullah Abu Bakar Brahim Aissa Dk Nur Afiqah Jalwati Puteri Amer Farhan Rafique 《地下水科学与工程》2019,(4):373-382
In many circumstances involving heat and mass transfer issues,it is considered impractical to measure the input flux and the resulting state distribution in the domain.Therefore,the need to develop techniques to provide solutions for such problems and estimate the inverse mass flux becomes imperative.Adaptive state estimator(ASE)is increasingly becoming a popular inverse estimation technique which resolves inverse problems by incorporating the semi-Markovian concept into a Bayesian estimation technique,thereby developing an inverse input and state estimator consisting of a bank of parallel adaptively weighted Kalman filters.The ASE is particularly designed for a system that encompasses independent unknowns and/or random switching of input and measurement biases.The present study describes the scheme to estimate the groundwater input contaminant flux and its transient distribution in a conjectural two-dimensional aquifer by means of ASE,which in particular is because of its unique ability to efficiently handle the process noise giving an estimation of keeping the relative error range within 10%in 2-dimensional problems.Numerical simulation results show that the proposed estimator presents decent estimation performance for both smoothly and abruptly varying input flux scenarios.Results also show that ASE enjoys a better estimation performance than its competitor,Recursive Least Square Estimator(RLSE)due to its larger error tolerance in greater process noise regimes.ASE's inherent deficiency of being slower than the RLSE,resulting from the complexity of algorithm,was also noticed.The chosen input scenarios are tested to calculate the effect of input area and both estimators show improved results with an increase in input flux area especially as sensors are moved closer to the assumed input location. 相似文献
35.
Brahim Meziani Djamel Machane Abderrahmane Bendaoud Ghani Cheikh Lounis El-Hadi Oubaiche Souhila Chabane Rabah Bensalem Hakim Moulouel 《Arabian Journal of Geosciences》2017,10(5):117
The Ain Turck (Bouira) landslide, in north-center Algeria, is one of the numerous instabilities recorded along the Lakhdaria-Bouira section of the 1200-km-long east-west Algerian highway. The locality of Ain Turck is known for its unstable slopes characterized by a very rough morphology with steep slopes (20 to 25%). This slide threatens the inhabitants of the Ibournanen village, located down the unstable slope, where parts of some houses have fallen into ruin, while others are cracked. It is characterized by an active movement extending over a more or less important slope, of the order of a hundred meters. The land mobilized by this movement corresponds to the layer of shale clays and clays overlaid by a backfill, placed there following the east-west highway works. Geological, geomorphologic, and geotechnical analysis allows determining the soil instability probably related to earthworks during the construction of the highway section a few years earlier, followed by a particularly rainy season in 2012. Acquisitions of ambient seismic noise and H/V ratio processing, as well as the acquisition of an electrical resistivity profile at the instability site, have reinforced our preliminary interpretations of depth and geometry of the sliding surface. 相似文献
36.
André Michard Abderrahmane Soulaimani Hassan Ouanaimi Youssef Raddi Lahsen Aït Brahim Ech-Cherki Rjimati Lahssen Baidder Omar Saddiqi 《Comptes Rendus Geoscience》2017,349(2):81-90
The Saghro Group (SG) is a folded, low-grade volcano-sedimentary series up to 8 km thick that crops out within and to the north of the Pan-African suture zone in the central and eastern Anti-Atlas. Here we describe the SG of the Ougnat inliers that are exposed in the easternmost Anti-Atlas beneath the unconformable, Late Ediacaran Ouarzazate Group (OZG) volcanic rocks. The Ougnat SG mostly consists of volcaniclastic greywackes accumulated in a peritidal-to-shallow basin. The basin infilling was deformed by NNE-trending, mostly upright folds with axial-planar slaty cleavage and low-grade metamorphism. The deformed SG rocks were intruded by the ～550 Ma Mellab hypovolcanic granodiorite. The latter also crosscuts the lowest OZG rocks that are dated to 574–571 Ma in the western Saghro region. The SG rocks that form the Siroua and Saghro inliers have an oldest age of 620–610 Ma and were folded at ～610–580 Ma at the onset of the Cadomian orogenic events. We show that the SG rocks are similar to the “Série verte” (SV) rocks that are exposed in the Ougarta and western Hoggar east of the Pan-African suture. We infer that the SG and SV rocks accumulated in a same, continuous basin that was bounding the West African Craton to the north and the east. This strongly subsiding basin formed close to a volcanic arc and was folded during the last Pan-African synmetamorphic events. Fold orientation and age of folding differ however along the edge of the West African Craton. The orogenic greywackes that form the remnants of the SG-SV basin thus constitute a precious record of the diachronic Cadomian event s.l. along the West African Craton northern margin. 相似文献
37.
F. Kaabouben A. I. Brahim E. Toto M. A. Baptista J. M. Miranda P. Soares J. F. Luis 《Journal of Seismology》2008,12(4):575-583
The 1975 May 26 earthquake, of magnitude Ms = 7.9, occurred in the North Atlantic close to the Azores Archipelago. Its epicentre,
as given by US Geological Survey, was 17.5° W, 35.9° N, 200 km south of the Gloria Fault. Several authors determined the focal
mechanism as a dextral strike-slip event with no significant dip-slip component, compatible with the relative motion between
Eurasia and Nubia plates but away from the presumed plate boundary. The 1975 earthquake generated a tsunami of small amplitude,
recorded at the Portuguese tide-gauge network, in Spain and Northern Africa. The peculiar location of the earthquake and tsunami
source and the generation of a noticeable tsunami were already discussed by several authors, but up to now, no direct modelling
of the tsunami generation and propagation was made to judge the set of source solutions obtained by seismological analysis.
In this paper, we present tsunami simulations, backward ray tracing and forward non-linear shallow water simulations using
data from Iberia and Azores and Northern Africa. We show that a good fit between observed data and synthetic waveforms can
be obtained with a focal mechanism with no significant dip-slip component, favouring its interpretation as almost pure dextral
strike-slip event located in an old fracture zone south of Gloria Fault. 相似文献
38.
BELATTMANIA Zahir CHAOUTI Abdellatif REANI Abdeltif MACHADO Margari ENGELEN Aschwin H SERR&#;O Ester A SABOUR Brahim 《海洋学报(英文版)》2018,37(10):190-194
The littoral paranthurid isopod crustacean Paranthura nigropunctata (Lucas, 1846) is recorded for the first time from the littoral of El Jadida located on the Atlantic northwest coast of Morocco. Specimens were obtained from the invasive brown seaweed Sargassum muticum and the natives Bifurcaria bifurcata and Cystoseira tamariscifolia in January 2015. This new record further confirms a significant southward distribution of P. nigropunctata and contributes to the knowledge of the biogeography of this isopod. Heretofore, the species was only known from the western and eastern Mediterranean and some Atlantic coasts. The present finding is the first of the species from Moroccan Atlantic shores, and suggests that the species may also be present in other coastal localities from Morocco and Africa. Some data on morphology, ecology and spatial distribution of the species are provided. 相似文献
39.
40.
Isolates of Staphylococcus aureus and saprophyticus resistant to antimicrobials isolated from the Lebanese aquatic environment 总被引：5，自引：0，他引：5
The indiscriminate use of antimicrobials especially in developing countries has evoked serious bacterial resistance and led to the emergence of new and highly resistant strains of bacteria to commonly used antimicrobials. In Lebanon, pollution levels and bacterial infections are increasing at a high rate as a result of inadequate control measures to limit untreated effluent discharges into the sea or freshwater resources. The aim of this study was to isolate and molecularly characterize various Staphylococcus strains isolated from sea water, fresh water, sediments, and crab samples collected from representative communities along the coast of Lebanon. The results on the antimicrobial resistance indicated that the level of resistance of Staphylococcus aureus varied with various antimicrobials tested. The resistance patterns ranged between 45% in freshwater isolates and 54.8% in seawater ones. Fifty one percent of the tested isolates have shown resistance to at least one of the five tested antimicrobials; with seawater isolates exhibiting the highest rates of antimicrobial resistance. 相似文献