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The present work is an analytical study of the influence of geometrical parameters, such as length, thickness and immersion of the plate, on the reflection coefficient of a regular wave for an immersed horizontal plate in the presence of a uniform current with the same direction as the propagation of the incident regular wave. This study was performed using the linearized potential theory with the evanescent modes while searching for complex roots to the dispersion equation that are neither pure real nor pure imaginary. The results show that the effects of the immersion and the relative length on the reflection coefficient of the plate are accentuated by the presence of the current, whereas the plate thickness practically does not have an effect if it is relatively small. 相似文献
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El Arbi Toto Chakib Kerrouri Lahcen Zouhri Mohamed El Basri Aomar Ibenbrahim Hafid Mohamad Mohamed Benammi 《水文研究》2008,22(11):1675-1686
An area of about 30 km2 located in Ain Jouhra, south of Rabat, Morocco, was the subject of a geoelectric resistivity investigation. The main goal of the investigation was the assessment of the groundwater potential of the uppermost aquifer. The aquifer conditions such as depth, thickness and boundaries were also investigated. The obtained apparent resistivity curves were first analysed qualitatively and classified using simple curve shapes. Thereafter, the data were converted to resistivity and thickness pairs semi‐quantitatively by means of master curves and then quantitatively by computer modelling using ATO and Winsev software (Zohdy, 1989; Zohdy and Bisdrof, 1989). Lithological control from the available single well with a stratigraphic log aided in the correlation of the resistivity values to different rock units. Three different AB‐spacing iso‐resistivity maps, an isopach map of the main groundwater‐bearing horizon, the depth to the aquifer substratum map and five geoelectric cross‐sections were constructed. The interpretation of these soundings indicates the presence of an unconfined to semi‐confined sandy aquifer with relatively important extent and varying thickness. The maximal thickness of the aquifer is recorded in the central part of the investigated area and is thinning southwards to pinch out farther to the south. Geophysical as well as field data indicate a hydraulic connection between the upper and deeper aquifers. Indeed, the two aquifers are separated from each other by a marly substratum that is indicated throughout the area by the lowest values of the interpreted true resistivity. The value of this resistivity varies laterally, most likely due to the lateral variation in the shale‐to‐sand ratio. The altitude of the substratum decreases towards the north, and increases southwards. Regarding the availability of the groundwater in the study area, zones with high potential are theoretically expected to occur in the central part where the transversal resistance is greatest. However, sufficient water supply and high flow rates from wells intended to produce restrictively from the most upper aquifer are not likely to exist. This conclusion, which seems to be very pessimistic, is evidenced from two real field and experimental observations. The first is the rapid fall of the level of Gharnoug lake, despite the ongoing feeding by three wells. Hence, the amount of water level drop cannot be accounted for by the evaporation alone. That means that the deeper aquifer is continuously draining the upper aquifer at a high flow rate. Very low rates are recorded in all the wells that penetrated only the upper aquifer, the exception being the well that reached deeper into the lower aquifer. The flow rate in this lower aquifer measured 18 litre s?1. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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Mohamed Chakib Lahmer Abdelmadjid Seddiki Mohamed Zerka Jean-Yves Cottin Mohammed Tabeliouna 《Arabian Journal of Geosciences》2018,11(12):332
A spinel ± amphibole ± feldspar bearing Iherzolites, a spinel ± amphibole ± feldspar bearing harzburgites, and a spinel ± amphibole ± phlogopite bearing wehrlites are metasomatized peridotitic mantle xenoliths from Ain Temouchent volcanic complex (North-West Algeria). These xenoliths are metamorphic/deformed rocks with a strong planar fabric typical of mantle tectonites. The wehrlites are not the result of a simple model of partial melting. The spinel ± amphibole ± feldspar bearing harzburgites and lherzolites exhibit asymmetric concave-shaped REE patterns. These indicate that an earlier partial melting event was followed by metasomatic processes. The wehrlites have higher REE concentrations and LREE/HREE fractionations, indicating a sequential evolution of wehrlites from previous refractory material with melting as an addition process. This process reflects the interaction of the lithospheric mantle beneath the Ain Temouchent area with basaltic melt. Metasomatism is expressed by the formation of amphibole, phlogopite, and increased abundances of clinopyroxene at the expense of orthopyroxene, in lherzolite and harzburgite. In the Ain Temouchent area, metasomatizing agents are Na-alkali silicates. The similarities observed between the glasses studied in this paper, and the basaltic host rocks of the Ain Temouchent area, may suggest a common mantle source, or with chemical similarities but with relatively different evolutions pathways. The formation of glass in wehrlites from the Ain Temouchent area has an origin formed by the breakdown of amphibole or phlogopite as a result of decompressional melting and production of silica-undersaturated glasses. The glass reacts with essentially orthopyroxene to produce silica-rich glasses. This study has contributed to highlighting a relationship between glass, and the processes that caused the formation of metasomatic phases. 相似文献
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