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Search Results: 1 - 10 of 10711 matches for " Ahmed Mostafa "
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Use of an Energy-Like Integral to Study the Motion of an Axi-Symmetric Satellite under Drag and Radiation Pressure  [PDF]
Ahmed Mostafa
International Journal of Astronomy and Astrophysics (IJAA) , 2015, DOI: 10.4236/ijaa.2015.53019
Abstract: The axi-symmetric satellite problem including radiation pressure and drag is treated. The equations of motion of the satellite are derived. An energy-like is given for a general drag force function of the polar angle θ, and then it is used to find a relation for the orbit equation of the satellite with initial conditions satisfying the vanishing of arbitrarily choosing higher derivatives of the velocity.
Efficient Information Set Decoding Based on Genetic Algorithms  [PDF]
Ahmed Azouaoui, Idriss Chana, Mostafa Belkasmi
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2012, DOI: 10.4236/ijcns.2012.57052
Abstract: In this paper, we describe a hard-decision decoding technique based on Genetic Algorithms (HDGA), which is applicable to the general case of error correcting codes where the only known structure is given by the generating matrix G. Then we present a new soft-decision decoding based on HDGA and the Chase algorithm (SDGA). The performance of some binary and non-binary Linear Block Codes are given for HDGA and SDGA over Gaussian and Rayleigh channels. The performances show that the HDGA decoder has the same performances as the Berlekamp-Massey Algorithm (BMA) in various transmission channels. On the other hand, the performances of SDGA are equivalent to soft-decision decoding using Chase algorithm and BMA (Chase-BMA). The complexity of decoders proposed is also discussed and compared to those of other decoders.
Towards a Semi-Kinematic Datum for Egypt  [PDF]
Mostafa Rabah, Ahmed Shaker, Magda Farhan
Positioning (POS) , 2015, DOI: 10.4236/pos.2015.63006
Abstract: Since 1990, positioning technology has undergone a dramatic improvement in terms of accuracy and accessibility. Prior to 1990, national geodetic datums were considered to be static with fixed coordinates assigned to the datum origin by convention. Datum coordinates were dynamic only as a consequence of re-observation and re-adjustment, or localized disturbance. This strategy has been suitable for terrestrial surveys within stable continental areas. The accessibility of Precise Point Positioning “PPP” is now widespread with the provision of free online processing facilities by various geodetic agencies. Such ready accessibility to a global datum has serious implication for this technology with static geocentric datums. The Geocentric Datum of Egypt (ITRF1994 Epoch 1996 based on GPS Observation Campaign 1996), for example, is now offset by -42.0 to +32.0cm from the ITRF2008 Epoch 2015 due to the inexorable tectonic movements of the Nubian plate since the datum realization in 1996. Unless the local geocentric datums are kept in step with global terrestrial reference frames, discrepancies between the two will increase in magnitude over time and will become discernable, even using PPP. The PPP users nowadays are unaware of this datum offset and incorrectly assume that a coordinated datum monument is in error if there is found to be a disagreement greater than the level of accuracy of the positioning technique. In this study, to avoid the discrepancies between the applied datum and On-Line GNSS Services, a semi-kinematic datum and related deformation mode are proposed for Egypt. The result also confirmed that the PMM model was giving good performance for the other parts out of Egypt. The evaluation study shows the best performances for the Egyptian deformation model over the ITRF2008 PMM.
Recent Techniques in Management of Lumbosacral Region Tumours: A Prospective Comparative Study  [PDF]
Mostafa Abd Elsamea, Mohamed Shaaban, Ahmed Taha
Open Journal of Modern Neurosurgery (OJMN) , 2018, DOI: 10.4236/ojmn.2018.82020

Background: The lumbosacral plexus consists of the ventral rami from the L2 to S3 nerve roots, with some additions from the L1 and S4 nerve roots as well. The standard treatment for spinal cord compression is urgent surgically decompressive laminectomy over the affected level with resection as much as possible of the exposed tumor to relieve the cord compression. We aim to correlate the impact of preoperative clinical picture, duration of symptoms, and the pathological nature of the lumbo-sacral spine tumors on the outcome of comparative study different modalities of management. Patients and Methods: During the period between 2015 and 2017, thirty cases were studied and surgically managed in Al-Azhar University Hospital, Damietta. Cases were selected for surgery if they were diagnosed as having a symptomatizing lumbosacral lesion. Results: Thirty patients were included in the current study; the commonest lesion in this study was ependymoma eight patients (27%), astrocytoma six patients (20%), and meningioma five patients (17%). Nerve sheath tumor comprised five cases (17%) with the hemangioblastomas three cases (10%), epidermoid one case (3%), and ependymoma of the filum terminale two cases (6%). The mean age of the included patients was 38.96 ± 15.42. The mean duration of lesions was 13.66 ± 10.93. They were 15 male patients (50%), and 15 female patients (50%), with male: female ratio 1:1. The mean duration of symptoms ranged for 1:60 months. The most common presenting manifestations were sensory followed by motor and sphinctric disturbance. Complications occurred in 8 patients (23%), and the most common was postoperative CSF leak. 19 out of 30 cases were surgically totally resected (63%), while 11 cases (37%) were grossly totally resected. Conclusions: Ependymoma and meningioma have more favorable outcome compared to other spinal tumors. Accurate and rapid diagnosis prior to surgery also associated with good outcome.

Evaluation of Hoffer Q formula in Short and long axial lengths
Ahmed I Galhoom, Mostafa M Mostafa
Egyptian Journal of Hospital Medicine , 2010,
Abstract: Purpose: Evaluation of The accuracy of Hoffer Q formula for intraocular lens (IOL) power calculation in short and long axial lengths of the eye. Methods: 100 eyes divided equally into 2 groups: group I (50 eyes) with axial length more than 24.5 and group II( 50 eyes) with axial length more less than 22. Comparison between both groups was done as regards post operative residual refractive error after IOL implantation using Hoffer Q formula. Results: Insignificant difference between the 2 groups as regard post operative residual refractive error. In short length eyes, the mean postoperative refractive error with Hoffer Q formula was 0.80 +0.33D. In long eyes, the mean postoperative refractive error was 1.23 +0.70D. The results show that the best performing formula was in short eyes (P = 0.012). Conclusion: Insignificant difference as regards postoperative residual refractive error between both groups but Hoffer Q formula best performed in short eyes.
Effect of Supplementation of Chelated Zinc on Milk Production in Ewes  [PDF]
Ayman Ahmed Hassan, Ghada Mostafa El Ashry, Soliman Mohamed Soliman
Food and Nutrition Sciences (FNS) , 2011, DOI: 10.4236/fns.2011.27097
Abstract: This study was carried out at the Noubaria Station, Animal Production Research Institute. Twelve Barki ewes at 3 - 4 years of age 45 ± 1.5 kg body weight were used in the present investigations. Animals were stratified for their initial body weight and age. Each group was composed of 4 pregnant animals at three months. All animals were housed in semi open pens in which water was ad-libitum. The first diet contains the basal diet plus 25 mg of Zn/kg DM as (ZnSO4·7H2O). The second and the third diets contain the basal diet plus 15 and 25 mg of Zn/kg DM as (Zn methionine, (ZnMet)) respectively. The inorganic Zn (ZnSO4·7H2O) caused a significant decline (P < 0.05) in digestibility coefficients, nutritive value, nitrogen utilization, Cell wall constituents, total VFA’s, rumen volume, microbial nitrogen synthesis and milk composition and yield compared to the both organic Zn (ZnMet). While, organic Zn (ZnMet) caused a significant decline (P < 0.05) in glucose and urea compared to the inorganic Zn (ZnSO4·7H2O). But inorganic or organic zinc did not cause any effect on the serum total protein (TP), albumin (A) concentration, globulin, creatinine, aspartates aminotransferase (AST) and alanine aminotransferase (ALT). The inorganic Zn (ZnSO4·7H2O) caused a significant decline (P < 0.05) in the antioxidants activity (GSH, GSH-Px, SOD and MDA) compared to the both organic Zn (ZnMet).
On the Computing of the Minimum Distance of Linear Block Codes by Heuristic Methods  [PDF]
Mohamed Askali, Ahmed Azouaoui, Sa?d Nouh, Mostafa Belkasmi
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2012, DOI: 10.4236/ijcns.2012.511081
Abstract: The evaluation of the minimum distance of linear block codes remains an open problem in coding theory, and it is not easy to determine its true value by classical methods, for this reason the problem has been solved in the literature with heuristic techniques such as genetic algorithms and local search algorithms. In this paper we propose two approaches to attack the hardness of this problem. The first approach is based on genetic algorithms and it yield to good results comparing to another work based also on genetic algorithms. The second approach is based on a new randomized algorithm which we call \"Multiple Impulse Method (MIM)\", where the principle is to search codewords locally around the all-zero codeword perturbed by a minimum level of noise, anticipating that the resultant nearest nonzero codewords will most likely contain the minimum Hamming-weight codeword whose Hamming weight is equal to the minimum distance of the linear code.
3D Object Recognition by Classification Using Neural Networks  [PDF]
Mostafa Elhachloufi, Ahmed El Oirrak, Aboutajdine Driss, M. Najib Kaddioui Mohamed
Journal of Software Engineering and Applications (JSEA) , 2011, DOI: 10.4236/jsea.2011.45033
Abstract: In this Paper, a classification method based on neural networks is presented for recognition of 3D objects. Indeed, the objective of this paper is to classify an object query against objects in a database, which leads to recognition of the former. 3D objects of this database are transformations of other objects by one element of the overall transformation. The set of transformations considered in this work is the general affine group.
Forced Convection Flow of Nanofluids Past Power Law Stretching Horizontal Plates  [PDF]
Fekry Mohamed Hady, Fouad Sayed Ibrahim, Hassan Mohammed Hassan El-Hawary, Ahmed Mostafa Abdelhady
Applied Mathematics (AM) , 2012, DOI: 10.4236/am.2012.32019
Abstract: In the present work, we studied a nonsimilar solution of steady forced convection boundary layer flow and heat transfer of a nanofluid past a stretching horizontal plate. One-phase model has been used for this study. The nonsimilarity equations are solved numerically. We considered a nanofluid consists of AL2O3 as a nanoparticles and water as a base fluid. The volume fraction of nanoparticles is considered in the range 0 ≤ ? ≤ 0.2. with prandtl number pr = 6.2 for the water working as a regular fluid. The parameters which governing the solution are volume fraction of nanoparticles , stretching plate parameter ξ and power law index N. We investigated the effect of these parameters on the skin friction coefficient, Nusselt number, velocity and temperature profiles. We found that heat transfer rate and skin fraction increased when ? increased. On the other hand, we concluded that the increase in ξ and N made heat transfer rate increases and skin fraction decreases.
Synthesis and characterization of a novel schiff base metal complexes and their application in determination of iron in different types of natural water  [PDF]
Mostafa M. H. Khalil, Eman H. Ismail, Gehad G. Mohamed, Ehab M. Zayed, Ahmed Badr
Open Journal of Inorganic Chemistry (OJIC) , 2012, DOI: 10.4236/ojic.2012.22003
Abstract: A novel, simple approach to the synthesis of macrocyclic Schiff base ligand resulted from the condensation of bisaldehyde and ethylenediamine was prepared (7, 8, 15, 16, 17, 18-hexahydrodibenzo (a, g) (14) annulene) (L) and its complexes were synthesized and characterized using different physicochemical studies as elemental analysis, FT-IR, 1H NMR, conductivity, magnetic properties, thermal analysis, and their biological activities. The spectroscopic data of the complexes suggest their 1:1 complexe structures which are investigated by elemental analysis, FT-IR, 1H NMR, conductivity, magnetic properties, thermal analysis, and their biological activities. The spectroscopic studies suggested the octahedral structure for the all complexes. The spectroscopic data of the complexes suggest their structure in which (N2O2) group act as a tetradentate ligand and two chlorides as monodentate ligands. Also electronic spectra and magnetic susceptibility measurements indicate octahedral structure of these complexes. The synthesized Schiff base and its metal complexes also were screened for their antibacterial and antifungal activity. Here we report the effect of a neutral chelating ligand on the complexation with iron to determine it in different types of natural water using recovery test. The activity data show that the metal complexes to be more potent/ antibacterial than the parent Schiff base ligand against one or more bacterial species.
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