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191.
192.
Osman M. Kamel 《Earth, Moon, and Planets》1990,49(3):269-276
In this part we present the complete solution of the planetary canonical equations of motion by the method of G. Hori through successive changes of canonical variables using the Lie series. Thus, we can eliminate the long or critical terms of the planetary perturbing function, in our general planetary theory. In our formulas, we neglect perturbation terms of order higher than the third with respect to planetary masses. 相似文献
193.
The aim of the present paper will be to utilize the results obtained in the preceding papers of this series for the development of practical procedures for obtaining the elements of any eclipsing system from the observed photometric data by their analysis in the frequency-domain, for any type of eclipses, any proximity of the two components, and any degree of the law of limbdarkening of the eclipsed star.In Section 2, which follows a brief introduction to the subject, procedures will be developed which should permit us to perform such an analysis — by hand or automatic machine computation — for the case of mutual eclipses in binary systems the components of which can be regarded as spheres; and whose apparent discs are characterized by an arbitrary radially symmetrical distribution of surface brightness. In Section 3 we shall generalize these procedures to systems consisting of arbitrarily distorted stars.Paper dedicated to Professor Hannes Alfvén on the occasion of his 70th birthday, 30 May, 1978. 相似文献
194.
Osman M. Kamel 《Earth, Moon, and Planets》1989,44(3):275-289
We explain how the first step of Hori-Lie procedure is applied in general planetary theory to eliminate short-period terms. We extend the investigation to the third-order planetary theory. We solved the canonical equations of motion for secular and periodic perturbations by this method, and obtained the first integrals of the system of canonical equations. Also we showed the relation between the determining function in the sense of Hori and the determining function in the sense of Von Zeipel. 相似文献
195.
196.
197.
Abdullahi Osman El-Tom 《GeoJournal》1998,46(2):163-170
This article assesses the state of female circumcision in the Sudan with the primary emphasis being placed on the Berti of
Darfur. Among other things, the article examines the factors that have so far led to the perpetuation of the practice and
the failure of the anti-circumcision campaign. The author suggests a renewal of the campaign through the use of a comprehensive
approach which encompasses the social, aesthetic, medical, identificational and religious variables involved in the practice.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
198.
Abdullahi Osman El-Tom 《GeoJournal》1998,46(2):155-161
Focusing on the Berti of Sudan, this article assesses the role of Islam and Arabism as important variables in the social construction
of cultural identity of the studied people. In line with most relevant recent literature, the author looks at cultural identity
as a social construct, a dynamic ideology of shifting borders and a historical process that is grounded on diachronic social
formation. The article argues that the present Berti identity is a conscious reflection of their subordinate position vis-à-vis
the kingdoms and states which have dominated Sudan over the past few centuries.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
199.
A. M. I. Osman 《Astrophysics and Space Science》1986,124(2):345-357
Detailed surface photometry for the SB(s)a galaxy NGC 7771 has been carried out in the blue spectral band. Isophotes, luminosity profiles, and photometric parameters are obtained from photographs collected with the 74 inch telescope of Kottamia Observatory, Egypt. The total apparent magnitudem
T
=13.08 with maximum dimensions 3.6±0.5×2.7±0.5 (at threshold µ
m
= 27.38 mag s–2). The absolute magnitude isM
T
=–21.70 if the distance is =90.2 Mpc. The major axis is in position angle =69°.5±1° and the mean axis ratio of the outer regionsq=b/a=0.45 corresponds to an inclinationi=66°. The equivalent effective radiusr
e
*
=0.29 and the effective surface brightness µ
e
= 22.30 mag s–2.The equivalent luminosity distribution has been decomposed into two main components, anr
1/4 spheroid and an exponential disk. The total apparent magnitudes of the spheroidal and disk components are 14.36 and 13.48, which correspond to contributions of 31 and 69% to the total blue luminosity, respectively. 相似文献
200.