ORIGINAL_ARTICLE
Progress of nonlinear Dust Acoustic Waves in Dust Plasma of Opposite Polarity
The propagation of dust-acoustic solitary waves in an magnetized collisionless plasma consisting of positive and negative dust, electrons and ions with Boltzmann distribution are examined. For nonlinear dust acoustic waves (DAWs), a reductive perturbation method was employed to obtain the Kortewege-de Vries (KdV) equation for the first-order potential. As the wave amplitude enlarged, the width and velocity of the wave deviate from the prediction of the KdV equation. Higher order analysis of the perturbed (KdV) equation was used to the fifth-order dispersion term. The effects of higher-order corrections on dust acoustic solitary structures are studied and discussed.
https://absb.journals.ekb.eg/article_22599_561cbcc3be5a3f9af24617162059e41a.pdf
2015-06-01
1
6
10.21608/absb.2015.22599
Dust acoustic waves Kortewege-de Vries (KdV) Equation
Solitary solution
ORIGINAL_ARTICLE
EVALUATION THE PERFORMANCE OF DOSE CALCULATION ALGORITHMS FOR HOMOGENEOUS AND HETEROGENEOUS PHANTOMS IN SBRT
Purpose: In Stereotactic body radiation therapy (SBRT), higher dose per fraction is delivered to patients and thus the need for an accurate dose computation is further elevated. So, the aim of this study is to evaluate the performance of the algorithms implemented in our treatment planning system.Methods: In this study different phantoms were designed to model the lung with a small tumor volume of size that are usually encountered in SBRT. Solid water and cork slabs were used in constructing the phantom body. Perspex pieces of different diameters were created to be inserted in precut holes in the cork to simulate the tumor. The various dose calculation algorithms that are implemented in our CMS XIO planning system were then used for dose calculation inside the target.Results: A significant discrepancies between maximum, minimum and mean dose for PTV was found between FFT Convolution, Fast superposition and superposition algorithms in dose calculation for the lung tumor. The FFT Convolution algorithms have higher calculated minimum dose than that predicted by the superposition and the fast superposition algorithm. A percentage difference up to 13.4% was obtained between the FFT Convolution and the superposition algorithm for the estimated maximum dose. Superposition and fast superposition showed little discrepancies for maximum, minimum and mean dose for the PTV.Conclusion: It is very critical to address the accuracy of dose computation for SBRT as a significant dose overestimation can occur inside the target due to the heterogeneous geometries.
https://absb.journals.ekb.eg/article_22600_31ec8fafdd4acad8f5b760aef0d65f80.pdf
2015-06-01
7
12
10.21608/absb.2015.22600
Dose calculation algorithms
Heterogeneous Phantoms
SBRT
ORIGINAL_ARTICLE
Effect Of Omega(782) Resonance on The Response Functions For d(e, eβ²Ο+)nn Reaction
In present work we study the effect of the Omega (Ο (782)) resonance on the response functions for the incoherent positive pion electroproduction forms the deuteron at different values for the four-momentum transfers squared (Q2) and the virtual photon lab energy (ππ0ππππππ). The study is carried out in the impulse approximation (IA) i.e. the final state interactions are neglected. The elementary amplitude for pion electroproduction is taken from the MAID-2007 model. The effect seems to be very small but almost increase with increasing the virtual photon lab energy.
https://absb.journals.ekb.eg/article_22601_a97127e71053ff7d40fc6d0809c95c5a.pdf
2015-06-01
33
50
10.21608/absb.2015.22601
pion electroproduction
the Ο (782) resonance
Invariant Amplitudes
CGLN amplitudes
Structure functions
the impulse approximation (IA). PACS numbers: 13.60.Le, 13.40.-f, 21.45.+v, 24.70+s, 25.30.Rw
Mahmoud
Tammam
1
Department of Physics, Faculty of Science, Al-Azhar University, Assiut Branch, Egypt.
LEAD_AUTHOR
Zakaria
Mahmoud
2
Department of Physics, Faculty of Science, Assiut University, New valley Branch, Egypt
AUTHOR
Mohamed
Koubisy
3
Department of Physics, Faculty of Science, Al-Azhar University, Assiut Branch, Egypt
AUTHOR
ORIGINAL_ARTICLE
COMPUTATIONAL ALGORITHM FOR THE EXPONENTIAL INTEGRAL
In this paper, an efficient computational algorithm for the exponential integral )(zEΟ
was established for all 21qiqv+= and biaz+=. The algorithm based on the evaluation of the continued fraction expansion of )(zEΟ
. Numerical applications of the algorithm are also given together with 3D plotes.
https://absb.journals.ekb.eg/article_22631_130834533bda0b3f131fe314625822af.pdf
2015-06-01
1
3
10.21608/absb.2015.22631
Exponential integral
computational algorithm
Numerical applications
SHARAF
M. A.
1
Department of Astronomy, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
LEAD_AUTHOR
ALRAWJIH
F. A.
2
Department of Mathematics, Faculty of Science, University of Dammam, Dammam, Saudi Arabia
AUTHOR
ORIGINAL_ARTICLE
Evaluation of the Elliptic Integrals
The present paper is devoted for establishing accurate computational algorithms for the incomplete and complete ellipticintegrals (EI) of the first, second and third kind. For these goals, we first derived some properties of EI that could be used tocheck the validity and the accuracy of the algorithms; in addition, particular continued fraction expansion of the ratio of thecomplete elliptic integrals of the second and first kinds is also derived. Secondly, we established the trigonometric seriesexpansions of EI, together with the recurrence formulae of their coefficients so as to facilitate the computations. Also,Gautschi's algorithm of the top-down continued fraction evaluation is described. Numerical applications are performed for:(a) the incomplete elliptic integrals using their trigonometric series expansions, (b) the complete elliptic integrals of thesecond kind from the complete elliptic integrals of the first kind using Gautschi's algorithm. Finally the numerical resultswere checked by two ways:i- by satisfying the conditions given by properties of EI.ii- by comparing their values with those list in slandered tables.In this respect, the numerical results show excellent arguments with these ways, a fact which proves the validity, accuracyand the effeteness of our algorithms
https://absb.journals.ekb.eg/article_22632_14d2aacfd0c4ad7bef1ac4ba106473e8.pdf
2015-06-01
5
15
10.21608/absb.2015.22632
recursive computations algorithms
continued fraction
trigonometric series expansions
Sharaf
M.A.
1
1Department of Astronomy, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
LEAD_AUTHOR
Alrawjih
F.A.
2
Department of Mathematics, Faculty of Science, University of Dammam, Dammam Saudi Arabia
AUTHOR
ORIGINAL_ARTICLE
Eclipses intervals for satellites in elliptical orbit under effects of solar radiation pressure and earthβs oblatness
The eclipse of a satellite in elliptical orbit is studied. The geocentric angle in the orbital plane between the perigee and conjunction point is determined. Eclipse times and duration of eclipse for elliptical orbits are obtained. The effects of the direct solar radiation pressure on the orbital elements are calculated taken into account the eclipses intervals. An application on the MOLNIYA 1-87 artificial satellite is done.
https://absb.journals.ekb.eg/article_22633_75059c37f65006e2b5b55a02f6363bbf.pdf
2015-06-01
17
22
10.21608/absb.2015.22633
Perturbations Theory
Circular orbital motion
Earthβs gravity
Radiation pressure effects
Shadow function
Ismail
M. N.
1
Departments of Astronomy and Metrology* Faculty of Science, Al-Azhar University, Egypt
LEAD_AUTHOR
Bakry
A.
2
Departments of Astronomy and Metrology* Faculty of Science, Al-Azhar University, Egypt
AUTHOR
Se lim
H. H.
3
National Research Institute of Astronomy and Geophysics (NRIAG)
AUTHOR
Shehata
M. H.
4
National Research Institute of Astronomy and Geophysics (NRIAG)
AUTHOR