Dual behavior of the toroidal magnetic field versus the Rossby wave instability     

Mahmoud Gholipour 《Astrophysics and Space Science》2016,361(12):385

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Numerical Prediction of Induced Pressure and Lift of the Planing Surfaces     

Hassan GHASSEMI  Ahmad Reza KOHANSAL  Mahmoud GHIASSI 《中国海洋工程》2009,23(2):221-232

This paper discusses the numerical prediction of the induced pressure and lift of the planing surfaces in a steady motion based on the potential flow solver as well as the spray drag by use of the practical method.The numerical method for computation of the induced pressure and lift is potential-based boundary element method.Special technique is identified to present upwash geometry and to determine the spray drag.Numerical results of a planing flat plate and planing craft model 4666 are presented.It is shown that the method is robust and efficient and the results agree well with the experimental measurements with various Froude humors.  相似文献   

Application of Rock Mass Characterization for Determining the Mechanical Properties of Rock Mass: a Comparative Study     

Mahmoud Hashemi  Sh. Moghaddas  R. Ajalloeian 《Rock Mechanics and Rock Engineering》2010,43(3):305-320

The results of geotechnical explorations, engineering geological investigation (including laboratory and in situ tests) and field observations have been used, along with borehole logging charts, to obtain the rock mass geotechnical data. Based on the data, the rock mass along the Sabzkuh water conveyance tunnel route was classified by rock mass rating (RMR), Q-system (Q), rock mass index (RMi) and geological strength index (GSI) (3 methods). A new series of correlations were established between the systems based on the data collected from the study area. These relationships were then compared with those reported in the literature, and two new relations were recommended. The classifications were utilized to calculate mechanical properties (rock mass strength and deformation modulus) of the rock mass along the tunnel according to available empirical relations, and to distinguish the upper-bound and lower-bound relations.  相似文献   

Heavy metal and anionic contamination in the water and sediments in Al-Mujib reservoir,central Jordan     

Waleed Manasreh  Iyad Hailat  Tayel Mahmoud El-Hasan 《Environmental Earth Sciences》2010,60(3):613-621

Sixty-five sediment samples and 25 water samples were collected from Al-Mujib reservoir, central Jordan, in order to investigate the heavy metal and ionic contamination assessment. Therefore, to achieve this aim, water and sediment samples were collected during winter and summer seasons (2007) from Al-Mujib reservoir and the areas surrounding it. The study shows that there are elevated levels of SO₄ ²⁻, Cl⁻ and Na⁺ in reservoir water, which might originate from anthropogenic activities in the reservoir catchment area. In addition, the reservoir water has higher total hardness (TH) values together with high Ca and Mg contents. This might be attributed to pH of reservoir water and the nature of the rocks exposed in the catchment area. The average levels of heavy metals in reservoir sediments are Fe = 14,888.1, Cu = 17.8, Zn = 88.6, Ni = 38.7, Cd = 4.4, Mn = 337.9 and Pb = 6.1 mg/kg, which are lower than that observed in Wadi Al-Arab reservoir, northern Jordan. The values of enrichment factor are Cd = 35.5, Ni = 3.02, Zn = 2.54, Cu = 1.26, Mn = 1.2 and Pb = 0.57; these values indicate that heavy metals in sediments of Al-Mujeb reservoir have a different anthropogenic incrimination inputs. The study showed that the sediments are polluted with Cd, relatively contaminated with Ni and Zn and uncontaminated with respect to Mn, Pb and Cu.  相似文献   

Petrogenesis of the Az Zabirah south zone bauxite ore deposits,central northern Saudi Arabia     

Al-Mutairi  Abdulaziz N.  Galmed  Mahmoud A.  Aldamegh  Khaled S. 《Arabian Journal of Geosciences》2015,8(4):2327-2339

Arabian Journal of Geosciences - The bauxite ore deposits are mainly found around the Az Zabirah area in the central northern part of Saudi Arabia. The age of the Az Zabirah bauxites was suggested...  相似文献   

Geoelectrical and Hydrogeochemical Studies for Delineating Ground-Water Contamination Due to Salt-Water Intrusion in the Northern Part of the Nile Delta, Egypt   总被引：3，自引：0，他引：3  

Abdel-Azim M. Ebraheem  Mahmoud M. Senosy  Kamal A. Dahab 《Ground water》1997,35(2):216-222

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Temperature variations of one well-known UV ceti type flare star     

Farouk M. Mahmoud 《Astrophysics and Space Science》1995,234(1):107-123

Temperature variations of the flare star, EV Lac, at its quiet-state luminosity were computed from its colour indices,B - V, which were measured in Johnson's system, these daily temperature changes are the essential reason of the short-term behaviour appearance in the flare star which is due to the presence of active region(s) causing a temperature difference of a few hundred degrees from the photosphere. A correlation between the annual mean of temperature variations of the flare star at its quiet-state and the annual rate of some physical parameters of the flare star at its active-state was detected. This correlation can interpret the occurrence of the long-term behaviour of the flare star at its quiescent-state as found by Mavridiset al. (1982).  相似文献   

Structure of magnetogasdynamic weak shock waves     

M. A. Khidr  S. S. Elghabaty  M. A. A. Mahmoud 《Astrophysics and Space Science》1987,136(2):379-391

The problem of the detailed structure of magnetogasdynamic shock waves is investigated. It is assumed that the flow takes place under normal magnetic fieldH ₀ and the conductivity of the medium is considered infinite. An approximate analytical solution of the nonlinear differential equations describing the phenomena is obtained. The suggested analytical results in this paper are in good agreement with the previous numerical computations for the thickness and the velocity distribution inside the transition region. In addition, the enthalpy distribution inside the shock front is predicted.  相似文献   

Interaction of ion beam with dust grains produces dust-acoustic solitary waves in Herbig-Haro objects     

S. K. El-Labany  W. M. Moslem  M. Mahmoud 《Astrophysics and Space Science》2012,339(1):185-193

Properties of dust-acoustic solitary waves in a warm dusty plasma are analyzed by using the hydrodynamic model for massive dust grains, electrons, ions, and streaming ion beam. For this purpose, Korteweg-de Vries (KdV) equation for the first-order perturbed potential and linear inhomogeneous KdV-type equation for the second-order perturbed potential have been derived and their analytical solutions are presented. In order to show the characteristics of the dust-acoustic solitary waves are influenced by the plasma parameters, the relevant numerical analysis of the KdV and linear inhomogeneous KdV-type equations are obtained. The dust-acoustic solitary waves, as predicted here, may be associated with the nonlinear structures caused by the interaction of polar jets with the interstellar medium, which is known as Herbig-Haro objects.  相似文献   

CFD-Based Model for Estimating the River Bed Morphological Characteristics near Cylindrical Bridge Piers Due to Debris Accumulation     

Al-Awadi  Aysar Tuama  Al-Khafaji  Mahmoud Saleh 《Water Resources》2021,48(5):763-773

Water Resources - The scour and flow field patterns with accumulation of debris around bridge piers are completely different due to the reduction of flow area and the increase in depth average...  相似文献