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Toufik E. Abdelatif 《Solar physics》1990,129(2):201-219
The nature and properties of magneto-atmospheric (MA) waves are discussed here. A simple model atmosphere, isothermal and permeated by a uniform vertical magnetic field, was used to find that there are two type of modes with avoided crossing of the eigencurves in a K - diagram. The properties of these waves are found to be identical to the uncoupled fast and slow MA waves away from the crossings (specially for small horizontal wave number K 1). The energy density for the fast modes is found to vanish with height and is responsible for the 3-min umbral oscillations, while the slow mode energy density is harmonic. 相似文献
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Aicha Berkane Mezhoud Samy Tayeb Bouzid Toufik Karech Abdelkader Noui 《Geotechnical and Geological Engineering》2022,40(4):2307-2318
Geotechnical and Geological Engineering - When designing tunnels, it is advisable to pre-estimate several tunnel parameters such as the depth (cover), the lining thickness, and the shape of the... 相似文献
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The linear oscillations of a stratified atmosphere embedded in a uniform vertical magnetic field are studied here. We use
a simple theoretical model, formed by the superposition of two isothermal layers, representing, respectively, i) the photosphere
and the chromosphere, and ii) the corona. The bottom layer behaves, for some modes, as a resonant cavity where MAG waves are
semi-trapped. We find the existence of two types of modes: 1) Fast modes which are trapped below the transition layer, 2)
Mixed modes which are resonant modes in the first layer and leak part of the energy to the corona. These mixed modes have
been found to be damped in the horizontal direction and can explain the observed slow modes in the corona. 相似文献
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Faiza Menjour Toufik Remmal Mustapha Hakdaoui Fouad El Kamel Kawtar Lakroud Fouad Amraoui Iz-Eddine El Amrani El Hassani Benjamin Van wyk de vries Pierre Boivin 《Journal of the Indian Society of Remote Sensing》2017,45(6):1015-1030
Karst formation geometry can be controlled by fractures and faults, and by other lithologies. Here we show the organization of kastic collapse features related to structures and to extensive basaltic lava flows in the Middle Atlas of Morocco. A lineament map of major faults and fractures has been created for the Middle Atlas using Landsat 7 ETM+ satellite images. This shows a dominant NE–SW regional direction and less prominent NNW–SSE and ENE–WSE directions. All these directions coincide with the alignments of karstic depressions that have formed in the Liassic limestones. The basaltic flows covering these formations on the Middle Atlas limestone plateau, have allowed the generation of cryptokarst, geometrically organized a long these major lineament directions. Karst landforms probabaly existed before the eruption of the lavas, but there were partly invaded by intrusions and volcanism. The extensive basaltic flows allowed for increased infiltration, and subsurface water flow, increasing the rate of kast formation after eruptions. Some basins show evidence of increased subsidence after lava emplacement (Aguelmam Sidi Ali Lake) and some maar-like craters also have subsided after eruption, by karts formation. We lay out the structural and lithological controls on Karstic formation in an intraplate volcanic field based on limestones and evaporites. 相似文献
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Abdı Amina Bouamrane Ali Karech Toufik Dahri Noura Kaouachi Anouar 《Geotechnical and Geological Engineering》2021,39(8):5675-5691
The main purpose of this study was to compare and evaluate the performance of two multicriteria models for landslide susceptibility assessment in Constantine, north-east of Algeria. The landslide susceptibility maps were produced using the analytic hierarchy process (AHP) and Fuzzy AHP (FAHP) via twelve landslides conditioning factors, including the slope gradient, lithology, land cover, distance from drainage network, distance from the roads, distance from faults, topographic wetness index, stream power index, slope curvature, Normalized Difference Vegetation Index, slope aspect and elevation. In this study, the mentioned models were used to derive the weighting value of the conditioning factors. For the validation process of these models, the receiver operating characteristic analysis, and the area under the curve (AUC) were applied by comparing the obtained results to The landslide inventory map which prepared using the archives of scientific publications, reports of local authorities, and field survey as well as analyzing satellite imagery. According to the AUC values, the FAHP model had the highest value (0.908) followed by the AHP model (0.777). As a result, the FAHP model is more consistent and accurate than the AHP in this case study. The outcome of this paper may be useful for landslide susceptibility assessment and land use management.
相似文献6.
Lakroud Kawtar Remmal Toufik Makhoukhi Samira Balcone-Boissard Hélène 《Mineralogy and Petrology》2020,114(2):119-128
Mineralogy and Petrology - A Ba- and Ti-rich mica (up to 14.0 wt% BaO and 13.1 wt% TiO2) occurs in nephelinites from the Middle Atlas Volcanic Province, Morocco. The rocks show a... 相似文献
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Lazhar Belkhiri Abderrahmane Boudoukha Lotfi Mouni Toufik Baouz 《Journal of African Earth Sciences》2011,59(1):140-148
Water analysis data of 54 groundwater samples from 18 uniformly distributed wells were collected during three campaigns (June, September and December 2004). Q-mode hierarchical cluster analysis (HCA) was employed for partitioning the water samples into hydrochemical facies. Interpretation of analytical data showed that the abundance of major ions was identified as follows: Ca ? Mg > Na > K and HCO3 ? Cl > SO4. Three major water facies are suggested by the HCA analysis. The samples from the area were classified as recharge area waters (Ca–Mg–HCO3 water), transition area waters (Mg–Ca–HCO3–Cl water), and discharge area waters (Mg–Ca–Cl–HCO3 water). Inverse geochemical modeling suggests that relatively few phases are required to derive the water chemistry in the area. In a broad sense, the reactions responsible for the hydrochemical evolution in the area fall into two categories: (1) evaporite weathering reactions and (2) precipitation of carbonate minerals. 相似文献
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AbstractExtracting built-up areas from remote sensing data like Landsat 8 satellite is a challenge. We have investigated it by proposing a new index referred as built-up land features extraction index (BLFEI). The BLFEI index takes advantage of its simplicity and good separability between the four major component of urban system, namely built-up, barren, vegetation and water. The histogram overlap method and the spectral discrimination index (SDI) are used to study separability. BLFEI index uses the two bands of infrared shortwaves, the red and green bands of the visible spectrum. OLI imagery of Algiers, Algeria, was used to extract built-up areas through BLFEI and some new previously developed built-up indices used for comparison. The water areas are masked out leading to Otsu’s thresholding algorithm to automatically find the optimal value for extracting built-up land from waterless regions. BLFEI, the new index improved the separability by 25% and the accuracy by 5%. 相似文献
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