Expansion theory for the elliptic motion of arbitrary eccentricity and semi-major axis     

Mohamed Adel Sharaf 《Astrophysics and Space Science》1983,93(2):377-401

In this paper of the series, elliptic expansions in terms of the sectorial variables θ _j ⁽ⁱ⁾ introduced in Paper IV (Sharaf, 1982) to regularise highly oscillating perturbation force of some orbital systems will be explored for the first four categories. For each of the elliptic expansions belonging to a category, literal analytical expressions for the coefficients of its trigonometric series representation are established. Moreover, some recurrence formulae satisfied by these coefficients are also established to facilitate their computations, numerical results are included to provide test examples for constructing computational algorithms.  相似文献   

Risk of dike failure due to flow slides     

M. B. de Groot  H. den Adel  T. P. Stoutjesdijk  C. J. van Westenbrugge 《Coastal Engineering》1995,26(3-4)

Flow slides may affect the stability of dikes. A flow slide is an instability of a submerged slope caused by liquefaction of loose, (medium) fine sand. Whether a flow slide will occur depends on the properties of the sand, which are a function of its density, and the geometry of the slope, as determined by wave and current induced scour and sedimentation. The influence of sand properties and the geometry parameters on the risk of flow slides are discussed. The application of a flow slide prediction method to an example and a risk analysis is briefly discussed.  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   

Timing and intensity of groundwater movement during Egyptian Sahara pluvial periods by U-series analysis of secondary U in ores and carbonates     

J.K Osmond  Adel A Dabous 《Quaternary Research》2004,61(1):85-94

Wet climatic episodes are known to have prevailed in the Egyptian Sahara several times during the late Quaternary, most recently during the Holocene 8000 yr ago. Earlier wet episodes have been recognized as having occurred during the past 300,000 yr and have been dated by U-series methods in speleothems and in lake travertines. We show here that the times of enhanced groundwater movement can also be determined by ²³⁰Th/²³⁴U dating of secondary U in ores of uranium, iron, and phosphate. We also present evidence that such acceleration of groundwater movements is indicated by relatively low ²³⁴U/²³⁸U activity ratios in the secondary uranium. Our new data show that pluvial periods in Egypt occurred during marine oxygen isotope stages 4, 5, 6, and 7 and therefore are consistent with the view that the wet episodes are the results of migration of the tropical monsoonal belt driven primarily by the 23,000-yr precession cycle of the Milankovich curve, modulated by the 100,000-yr eccentricity cycle.  相似文献   

Surface mapping of the Milh Kharwah salt diapir to better understand the subsurface petroleum system in the Sab’atayn Basin,onshore Yemen     

Gabor Tari  Leslie Jessen  Patrick Kennelly  Adel Salman  Thomas Rainer  Peter Hagedorn 《Arabian Journal of Geosciences》2018,11(15):428

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Assessment of the reliability of supervised classifications of Landsat-7, ASTER,and SPOT-5 multispectral data in rock unit discriminations of Jabal Daf-Wadi Fatima area,Saudi Arabia     

Adel Zein Bishta 《Arabian Journal of Geosciences》2018,11(23):755

Multispectral, multiresolution remotely sensed data were processed to emphasize geological interpretation of Jabal Daf-Wadi Fatima area. The investigated area is situated in the central western part of Saudi Arabia and geologically consists of igneous and metamorphosed rocks overlain by sedimentary sequence belonging to the Arabian-Nubian Shield. Three sets of digital satellite data, Landsat-7 ETM+, ASTER, and SPOT-5, were used in this study. The application of image processing techniques enables to identify and delineate the lithologic units and the structural features of the study area. The results of this study indicate that the confusion matrix of the three maximum likelihood supervised classifications of the three datasets shows that the Landsat ETM+ bands scored the best degree of average and overall accuracy (77 and 78%, respectively). This classification distinguishes most of the rock units for mapping in the investigated area. The supervised classification of ASTER and SPOT bands has lower degrees of accuracy than the classified Landsat data. The supervised classification of SPOT bands has a degree of average and overall accuracy of 66 and 67%, respectively, but it is the best for distinguishing the spectral signatures of the different members of Fatima Formation (lower, middle, and upper members). The statistical analyses of the confusion matrices of classifications and the interpretation of the produced classified thematic maps revealed that the classification accuracy does not necessary depend on the spatial resolution of satellite data. The data of the highest spatial resolution such as SPOT data are also very useful in emphasizing and classifying the rock units of a small outcrop area. The detailed geological map of Jabal Daf-Wadi Fatima area is interpreted in this work from supervised classified images of different resolutions as well as the structure map of this area. This study shows that it is preferable to use the supervised classifications of multiresolution data for rock unit discrimination in detailed field mapping.  相似文献   

Provenance,weathering, and paleoenvironment of the Upper Cretaceous Duwi black shales,Aswan Governorate,Egypt     

Samir M. Zaid  Oussama A. EL-Badry  Adel M. Akarish  Mahmoud A. Mohamed 《Arabian Journal of Geosciences》2018,11(7):147

The mineralogy and geochemistry of the Upper Cretaceous Duwi black shales of Nile Valley district, Aswan Governorate, Egypt, have been investigated to identify the source rock characteristics, paleoweathering, and paleoenvironment of the source area. The Duwi Formation consists mainly of phosphorite and black shales and is subdivided into three members. The lower and upper members composed mainly of phosphorite beds intercalated with thin lenses of gray shales, while the middle member is mainly composed of gray shale, cracked, and filled with gypsum. Mineralogically, the Duwi black shales consist mainly of smectite and kaolinite. The non-clay minerals are dominated by quartz, calcite, phosphate, dolomite, feldspar, with little gypsum, anhydrite, iron oxides, and pyrite. Based on the CIA, PIA, and CIW values (average?=?84, 94, 95, respectively), it can be concluded that the litho-components of the studied shales were subjected to intense chemical weathering and reflect warm/humid climatic conditions in the depositional basin. The provenance discrimination diagram indicates that the nature of the source rocks probably was mainly intermediate and mafic igneous sources with subordinate recycled sedimentary rocks (Nubia Formation). Geochemical characteristics indicate that the Duwi black shales in Nile Valley district were deposited under anoxic reducing marine environments.  相似文献   

Seepage Through Earth Dams with Internal Cut Off     

Attia  Michael  Abdel Razek  Mohamed  Salam  Adel Abdel 《Geotechnical and Geological Engineering》2021,39(8):5767-5774

Geotechnical and Geological Engineering - Failure in earth dams mainly occurs due to seepage to the unprotected downstream face of the dam. Therefore, many precautions are taken into consideration...  相似文献   

Mineralogy and geochemistry of fine-grained Dahab stream sediments,Southeastern Sinai,Egypt: emphasis on the intergrowths of Fe–Ti oxides     

Surour  Adel A.  El-Kammar  Ahmed. M. A.  Arafa  Ebtisam H.  Korany  Hala M. 《中国地球化学学报》2021,40(6):871-894

Acta Geochimica - Mineralogical and geochemical characteristics of stream sediments collected from 30 stations in the Dahab-Wadi Kid area (southeastern Sinai, Egypt) are presented. The studied...  相似文献   

A theoretical analysis and control study of open-circuit grinding     

G.T. Adel  A.G. Ulsoy  K.V.S. Sastry 《International Journal of Mineral Processing》1983,10(1):25-43

Regrinding is an essential step in many mineral processing flowsheets as a final preparatory step for mineral separation. It is normally carried out in open-circuit ball mills or rod mills. Wide fluctuations occurring in the hardness and size distribution of feed materials to regrinding mills result in a nonuniform product fineness and processing inefficiency. Using a previously developed regrinding model, this paper presents the dynamic analysis and design considerations of a control system for open-circuit grinding, using the traditional P-, PI-, and PID-control algorithms. This study shows the utility of simple analysis techniques in designing a mineral process control system with special attention given to the effect of sampling and analysis time on control system performance.  相似文献