On the A-transform of the exponential integrals     

Mohamed Adelsharaf 《Astrophysics and Space Science》1979,60(1):199-212

In this paper, a technique of recursive analysis is developed for the integral transform A of the exponential integral functionsE _n which is denoted as _n (). The main result of this analysis enables us to establish a two-term recurrence formula for _n (0) and a three-term recurrence formula for _n (); 0. A computational algorithm based on these formulae is also constructed and its numerical results forn=2(1)25 are presented to 15-digit accuracy.  相似文献   

Comment on “The Moroccan Hercynides” by Hoepffner et al. (Journal of African Earth Sciences, vol. 43, pp. 144–165)     

Martin Roddaz  Jean-Claude Soula  Mohamed Ben Abbou  Stphane Brusset  Pierre Debat  Ahmed Ntarmouchant  Youssef Driouch  Didier Bziat 《Journal of African Earth Sciences》2006,45(4-5):515-517

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The Role of Fractional Crystallization and Assimilationin the Evolution of the Zoned Mukhattata Pluton, Eastern Desert, Egypt     

Said A. El-Nisr  Mohamed M. El-Sayed 《Chemie der Erde / Geochemistry》2002,62(3):216-236

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Structure sismique du socle paléozoı̈que du bassin des Doukkala,Môle côtier,Maroc occidental. Indication en faveur de l'existence d'une phase éo-varisqueSeismic structure of the Doukkala basin,Palaeozoic basement,western Morocco: a hint for an Eovariscan fold-and-thrust belt     

Hassan Echarfaoui  Mohamed Hafid  Abdallah Aı̈t Salem 《Comptes Rendus Geoscience》2002,334(1):13-20

Seismic profiles and well data from the Doukkala basin unravel the structure of the Palaeozoic basement and suggest that this coastal zone of western Morocco was affected by a compressive phase during the Frasnian. This resulted in the formation of upright, plurikilometric folds associated with reverse faults (North Doukkala), and of asymmetrical folds associated with mostly west verging ramps (South Doukkala). Folding involved all pre-Upper Frasnian formations and caused partial or total hiatus of Upper Frasnian–Strunian strata. This event can be correlated with the orogenic phase reported from more internal domains of the Morocco Hercynian belt, where it is referred to as the ‘Bretonne’ or ‘Eovariscan’ phase. To cite this article: H. Echarfaoui et al., C. R. Geoscience 334 (2002) 13–20  相似文献   

Caractérisation des paragenèses et des paléocirculations fluides dans l'indice d'or de Bleı̈da (Anti-Atlas,Maroc)Characterization of the paragenesis and the fluid palaeo-circulations in the gold showings of Bleida (Anti-Atlas,Morocco)     

Ahmed Barakat  Christian Marignac  Marie-Christine Boiron  Mohamed Bouabdelli 《Comptes Rendus Geoscience》2002,334(1):35-41

The gold showings at Bleida are hosted in Late Pan-African N50–80 °E quartz–hematite–chlorite 1 tension lenses that are related to the activity of major sinistral sub-east–west thrusts. Ores result from three superimposed stages of fluid migration. Gold occurs in microcracks offsetting the earlier minerals. Fluids evolved from COHN compositions with a saline component to boiling aqueous fluids. Pressure and temperature decreased from 50 MPa and 300 °C to less than 4 MPa and 150 °C. Thus, the gold showings at Bleida were formed in a typical geothermal (epithermal) setting, likely controlled by the Late Pan-African magmatism. To cite this article: A. Barakat et al., C. R. Geoscience 334 (2002) 35–41  相似文献   

Premier pôle paléomagnétique,d'âge Moscovien contraint par un test du pli,obtenu dans le bassin d'Illizi (Craton saharien,Algérie)First palaeomagnetic pole,of Moscovian age constrained by a fold test,in the Illizi Basin (Saharan Craton,Algeria)     

Boualem Bayou  Mohamed El-Messaoud Derder  Bernard Henry  Hamou Djellit  Mohamed Amenna 《Comptes Rendus Geoscience》2002,334(2):81-87

Palaeomagnetic study, carried out in the Moscovian (～305 Ma) formation in the Edjeleh anticline, shows the existence of three magnetisation components. Two of them are probably Cenozoic and Permian remagnetisations. The third component determined by both well defined ChRMs and remagnetisation circles analysis passes the fold test. Because the folding started before or during the Stephano-Autunian, this third component is the primary magnetisation. Its palaeomagnetic pole (28.3°S, 58.9°E), close to other poles from the Saharan platform obtained from neighbouring periods but without palaeomagnetic tests, confirms the age of these last data. To cite this article: B. Bayou et al., C. R. Geoscience 334 (2002) 81–87.  相似文献   

Deep structure of the northeastern margin of the Parnaiba Basin, Brazil, from magnetotelluric imaging   总被引：1，自引：0，他引：1  

Adel K. Mohamed  Maxwell A. Meju  Sergio L. Fontes 《Geophysical Prospecting》2002,50(6):589-602

The magnetotelluric (MT) method has been applied to the determination of the deep resistivity structure of the northeastern margin of the Parnaiba Basin. Transient electromagnetic (TEM) and MT data were collected in early 1999 along a 95 km long N–S line, extending from the coast across the projected subcrop position of a discontinuous fault found to the west of the study area that is believed to be a possible basin‐bounding fault. The MT data were processed to yield the TE‐ and TM‐mode responses and then corrected for static shift using central‐loop and single‐loop TEM data, respectively. Regularized 2D MT inversion was subsequently undertaken using a structured initial model with the near‐surface constrained by TEM inversion results. As a consistency check, we performed another set of 2D inversions using different smooth initial models. The various optimal 2D inversion models show clearly the presence of a major basement trough, over 2 km deep, located about 70 km from the coast. We interpret it as possibly marking the main basin margin and suggest that it may have implications for groundwater resource development in the area.  相似文献   

Screening model for volatile pollutants in dual porosity soils     

Mohamed M. Hantush  Rao. S. Govindaraju  Miguel A. Marioand Zhonglong Zhang 《Journal of Hydrology》2002,260(1-4):58-74

This paper develops mass fraction models for transport and fate of agricultural pollutants in structured two-region soils. Mass fraction index models, based on a semi-infinite domain solution, are derived that describe leaching at depth, vapor losses through soil surface, absorption, and degradation in the dynamic- and stagnant-water soil regions. The models predict that leaching is the result of the combined effect of the upward vapor-phase transport relative to downward advection, residence time relative to half-life, dispersion, and lateral diffusive mass transfer. Simulations show that leached fraction of volatile compounds does not always decrease monotonically with increased residence time relative to the pollutant half-life, as a result of complex interactions among the different physical and biochemical processes. The results show that leaching, volatilization, and degradation losses can be affected significantly by lateral diffusive mass transfer into immobile-water regions and advection relative to dispersion (i.e. Peclet number) in the mobile-water regions. It is shown that solute diffusion into the immobile phase and subsequent biochemical decay reduces leaching and vapor losses through soil surface. Potential use of the modified leaching index for the screening of selected pesticides is illustrated for different soil textures and infiltration rates. The analysis may be useful to the management of pesticides and the design of landfills.  相似文献   

Les dykes basiques du massif ancien de l'Ourika (Atlas de Marrakech,Maroc) : géochimie et significationThe basic dykes of the Ourika old massif (High Atlas of Marrakech): Geochemistry and significance     

Ahmed Barakat  Christian Marignac  Mohamed Bouabdelli 《Comptes Rendus Geoscience》2002,334(11):827-833

The Precambrian massif of Ourika is crosscut by two systems of basic dykes, striking N40°E and N90–120°E. Using incompatible trace elements, the two systems form two distinct chemical groups, displaying a continental tholeiitic affinity. The composition variations between the two defined groups can be due to heterogeneities of mantle sources and to contamination, during the magma ascent, by the continental crust. The emplacement of these basic dykes, before the late-PIII formations, can be related to the Neoproterozoic distension generalised to the Anti-Atlas chain. To cite this article: A. Barakat et al., C. R. Geoscience 334 (2002) 827–833.  相似文献   

Effet de l'agrégation sur le transport de la kaolinite recouverte d'acide humique à travers un sable de quartz d'origine naturelleAggregation effect on the transport of humic-coated kaolinite colloids through a natural quartz sand     

Rachid Ait Akbour  Jamaâ Douch  Mohamed Hamdani  Philippe Schmitz 《Comptes Rendus Geoscience》2002,334(13):981-985

To evaluate the risk of contaminant transport by mobile colloids, it is necessary to understand how colloids and associated pollutants behave during their migration through uncontaminated soil or groundwater. In this study, we investigated the influence of aggregation induced by Ca²⁺ and trace metals (Pb²⁺, Cu²⁺) concentrations on the transport of humic-coated kaolinite colloids through a natural quartz sand at pH=4. Adsorbed divalent cations reduce the colloids surface charge and thereby induce aggregation and deposition in porous media. To cite this article: R. Ait Akbour et al., C. R. Geoscience 334 (2002) 981–985.  相似文献