Analytical expansion of the earth's zonal potential in terms of ks regular elements     

M.A. Sharaf  A.S. Saad 《Celestial Mechanics and Dynamical Astronomy》1996,66(2):181-190

In this paper, the expansion of the Earth's zonal potential is established analytically in terms of KS regular elements whatever the power of the eccentricity e(e < l) and the number of the zonal harmonics may be.  相似文献   

Energy albedo for multiregion slabs     

E. A. Saad  M. A. El Gazzar  M. S. Abdel Krim  S. A. El Wakil 《Astrophysics and Space Science》1984,107(1):11-18

An asymptotic solution for the equation of radiative transfer in an inhomogeneous medium was obtained on the basis of the corresponding solutions for homogeneous sub-layers in the slowing down region. Function relations between the reflection and transmission coefficients for the whole slab and those of the sublayers are given. The invariant embedding concepts are used to get the reflection and transmission coefficients for the sub-layers. We assumed different models for the slowing-down kernels. Laplace transform was used to transform the Boltzmann equation to one velocity approximation with re-scaled mean-free path and single-scattering albedo. Numerical results are given for energy albedo as a function of the mass number of the host medium.  相似文献   

Radiation transfer for an inhomogeneous half-space with an internal source     

E. A. Saad  A. A. Hendi  S. A. El Wakil 《Astrophysics and Space Science》1984,100(1-2):381-389

The emergent flux for radiation transfer in an inhomogeneous half-space with internal source is obtained in terms of the source-function of the diffuse reflection problem. Modified Eddington method is used to calculate the diffuse problem and, hence, the emergent flux. Numerical result are given and compared with previous work.On leave of absence from the Nuclear Research Centre, Cairo, Egypt.  相似文献   

Enhancement of edges of Sidi Chennane phosphate “disturbances” using sunshading responses of resistivity data     

Saad Bakkali   《Russian Geology and Geophysics》2007,48(9):775-781

Sunshading is a powerful tool for the enhancement of edges in images. Given the azimuth and elevation of a source illumination, it calculates the reflectance from a surface which is composed of the data to be interpreted. It is a standard tool used in the interpretation of geophysical potential field data. In the great Oulad Abdoun phosphate basin, inclusions of sterile hardpan — so-called “disturbances” — are hard to detect as they interfere with phosphates. Their resistivity is above 200 Ohmm against 80 to 150 Ohmm for a phosphate-rich mineral. A Schlumberger resistivity survey over an area of 50 hectares was carried out. The geologic setting was successfully modeled on the basis of sunshaded maps of disturbances. A new field procedure was tested to deal with the extended edges of anomalous zones of phosphate deposit disturbances. Phosphate reserves were estimated more reliably.  相似文献   

An efficient computational algorithm for the initial value problem associated with the universal Y functions     

M. A. Sharaf  A. S. Saad  M. A. Fadak 《Astronomische Nachrichten》2016,337(3):235-238

In the present paper, an efficient iterative method of arbitrary integer order of convergent ≥2 based on the homotopy continuation techniques for the solution of the initial value problem of space dynamics using the universal Y functions is presented. The method is of dynamic nature in the sense that, ongoing from one iterative scheme to the subsequent one, only additional instruction is needed. Most importantly, the method does not need any prior knowledge of the initial guess. This is a property which avoids the critical situations between divergent to very slow convergent solutions that may exist in other numerical methods which depend on initial guesses. A computational package for digital implementation of the method is given, together with numerical applications for elliptic, hyperbolic, and parabolic orbits. The accuracy of the results for all orbits is O(10^–16). (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

Comparison of Early Succession and Scleractinian Recruitment Between Artificial Live Rocks and Terracotta Tiles     

Hamizan  Yusof Muhammad  Saad  Shahbudin  Naim  Mohd Azrul  Khodzori  Mohd Fikri Akmal  Hanapiah  Muhammad Faiz Mohd 《Ocean Science Journal》2021,56(3):317-325

Ocean Science Journal - Previous studies indicated that artificial live rock (ALR) has the potential to be used as a substrate for coral juveniles. The present study reported a potential of ALR as...  相似文献   

Saudi Arabian White Silica as a Good Adsorbent for Pollutants          下载免费PDF全文

Islam Hamdy Abd El Maksod  Hassan M. AlBishri  Abdullah Saad Al‐bogami 《洁净——土壤、空气、水》2014,42(4):480-486

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Effects of anthropogenic activities on the quality of surface water of Seybouse River (northeast of the Algeria)     

Asma Reggam  El-Hadi Bouchelaghem  Saad Hanane  Moussa Houhamdi 《Arabian Journal of Geosciences》2017,10(10):219

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A nested multivariate copula approach to hydrometeorological simulations of spring floods: the case of the Richelieu River (Québec,Canada) record flood   总被引：2，自引：2，他引：0  

Christian Saad  Salaheddine El Adlouni  André St-Hilaire  Philippe Gachon 《Stochastic Environmental Research and Risk Assessment (SERRA)》2015,29(1):275-294

Floods have potentially devastating consequences on populations, industries and environmental systems. They often result from a combination of effects from meteorological, physiographic and anthropogenic natures. The analysis of flood hazards under a multivariate perspective is primordial to evaluate several of the combined factors. This study analyzes spring flood-causing mechanisms in terms of the occurrence, frequency, duration and intensity of precipitation as well as temperature events and their combinations previous to and during floods using frequency analysis as well as a proposed multivariate copula approach along with hydrometeorological indices. This research was initiated over the Richelieu River watershed (Quebec, Canada), with a particular emphasis on the 2011 spring flood, constituting one of the most damaging events over the last century for this region. Although some work has already been conducted to determine certain causes of this record flood, the use of multivariate statistical analysis of hydrologic and meteorological events has not yet been explored. This study proposes a multivariate flood risk model based on fully nested Archimedean Frank and Clayton copulas in a hydrometeorological context. Several combinations of the 2011 Richelieu River flood-causing meteorological factors are determined by estimating joint and conditional return periods with the application of the proposed model in a trivariate case. The effects of the frequency of daily frost/thaw episodes in winter, the cumulative total precipitation fallen between the months of November and March and the 90th percentile of rainfall in spring on peak flow and flood duration are quantified, as these combined factors represent relevant drivers of this 2011 Richelieu River record flood. Multiple plausible and physically founded flood-causing scenarios are also analyzed to quantify various risks of inundation.  相似文献   

Signature of the 27-day variation in hemispheric sunspot activity and asymmetry during 2010-2015     

Prithvi Raj Singh  Ahmad Islam Saad Farid  Tarun Kumar Pant  Abhay Kumar Singh 《天文和天体物理学研究(英文版)》2021,(4):253-262

In the present work,we study the time evolution,significance of the N-S asymmetry excesses presented as a function of the solar cycle and prominent rotational p...  相似文献