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Search Results: 1 - 10 of 484477 matches for " Mohamed A. Ali "
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Optimal Convergence Analysis for Convection Dominated Diffusion Problems  [PDF]
M. A. Mohamed Ali
Journal of Applied Mathematics and Physics (JAMP) , 2013, DOI: 10.4236/jamp.2013.13004

In classical mixed finite element method, the choice of the finite element approximating spaces is restricted by the imposition of the LBB consistency condition. The method of H1-Galerkin mixed finite element method avoids completely the imposition of such a condition on the approximating spaces. In this article, we discuss and analyze error estimates for Convection-dominated diffusion problems using H1-Galerkin mixed finite element method, along with the method of characteristics. Optimal order of convergence has been achieved for the error estimates of a two-step Euler backward difference scheme.

Treatment of Resistant Clubfoot with Soft Tissue Release and Alkhooly External Fixator  [PDF]
Ali Zein A. A. Al-Khooly, Mohamed Ali Ahmed Mohamed, Ebrahim El-Hawary Ali
Open Journal of Orthopedics (OJO) , 2013, DOI: 10.4236/ojo.2013.37058

After the first research with this technique done by the first author, ten operations on the foot and ankle were performed on five patients (two boys and three girls) suffering from severe club foot deformity all with bilateral foot affection. Their ages ranged from five to fourteen years. All of them were treated by soft tissue release, skin flap (rotational flap), supplemented with Alkhooly external fixator. The follow up period ranged from two to seven years. The results according to Mittal (1987) [1] were excellent in eight feet (80%) and good in two feet (20%).



Catalyst Free Synthesis of Pyridine-2,6-bis(2-bromo-propane-1,3-dione) and Pyrdine-2,6-bis(N-arylthiazoline-2-thiones)  [PDF]
Korany A. Ali, Mohamed A. Elsayed, Eman Ali Ragab
Green and Sustainable Chemistry (GSC) , 2015, DOI: 10.4236/gsc.2015.51006
Abstract: We have described herein a catalyst-free preparation method of pyridine-2,6-bis(N-alkylthiazoline-2-thiones) (4a-i) by the reaction of primary amines, CS2, and pyridine-2,6-bis(2-bromo-1,3- dicarbonyl) derivatives (2a-c) in water. Also, we have described a catalyst free, green chemistry protocols to monobromination of pyridine-2,6-bis(2-bromo-1,3-dicarbonyl) derivatives with high yield, using NBS as a brominating agent, that led to eco-friendly isolation and purification proce-dures. Furthermore, we have studied the reactivity of pyridine-2,6-bis(2-bromo-1-methyl-pro- pane-1,3-dione) (2a) towards thiourea to afford 2,6-bis(5-benzoyl-2-aminothiazol-4-yl)pyridine (9).
Interactive Kalman Filtering for Differential and Gaussian Frequency Shift Keying Modulation with Application in Bluetooth  [PDF]
Mahdi N. Ali, Mohamed A. Zohdy
Journal of Signal and Information Processing (JSIP) , 2012, DOI: 10.4236/jsip.2012.31009
Abstract: Some applications are constrained only to implement low cost receivers. In this case, designers are required to use less complex and non-expensive modulation techniques. Differential Quadrature Phase Shift Keying (DQPSK) and Gaussian Frequency Shift Keying (GFSK) can be non-coherently demodulated with simple algorithms. However, these types of demodulation are not robust and suffer from poor performance. This paper proposes a new method to enhance the performance of DQPSK and GFSK using Interactive Kalman Filtering (IKF) technique, in which a one Unscented Kalman Filter (UKF) and two Kalman Filters (KF) are coupled to optimize the demodulated signals. This method consists of simple but very effective algorithms without adding complexity to the demodulators comparing to other very complex methods. UKF is used in this method due to its superiority in approximating and estimating nonlinear systems and its ability to handle non-Gaussian noise environments. The proposed method has been validated by creating a MATLAB/SIMULINK Bluetooth system model, in which the IKF is integrated into the receiver, which implement both DQPSK and GFSK, and run simulation in Gaussian and Non-Gaussian noise environments. Results have shown the effectiveness of this method in optimizing the received signals, and that the UKF outperforms the Extended Kalman Filter (EKF).
Post-Aneurysmal Subarachnoid Hemorrhage Vasospasm, Clinical Correlation between the Aneurysm Site and Clinical Vasospasm  [PDF]
Ahmed Ali, Mohamed A.R. Soliman
Open Journal of Modern Neurosurgery (OJMN) , 2018, DOI: 10.4236/ojmn.2018.83025
Abstract: Background: Intracranial vasospasm is a common complication following subarachnoid hemorrhage (SAH). The radiographic vasospasm can reach up to 90% of aneurysmal SAH. Materials and Methods: 139 consecutive patients admitted to Cairo University Hospitals from June 2013 to September 2014 with SAH who had been enrolled in a retrospective controlled study were analyzed retrospectively for the occurrence of vasospasm. The data collected from the charts of Cairo University Hospitals were the patient’s demographics, clinical presentation, aneurysm location, treatment modality, and Glasgow Outcome Scale (GOS) scores. We excluded 24 patients with nonaneurysmal SAH, 3 internal carotid artery (ICA) aneurysms, 7 with multiple aneurysms and 4 patients died before treatment. Results: 72 males and 29 females were included in the study, mean age 53.5 ± 11.5 years. Twelve patients had aneurysms located in the vertebral artery group, 24 had middle cerebral artery aneurysms, 11 had pericallosal aneurysms, and 54 patients had anterior communicating artery (ACoA) complex aneurysms. Radiographic vasospasm occurred in 62.4% with the highest incidence (75.9%) at the ACoA complex group. Symptomatic vasospasm occurred in 48.5% with the highest incidence (63%) at the anterior communicating artery complex aneurysm location. The mean GOS at 6 months follow-up was 4.2. The worse GOS was found in the vertebral artery (VA) aneurysm group with a mean of 3.75. Conclusion: Aneurysms of the anterior communicating artery complex group have a greater risk of both radiographic and clinical vasospasm. Also, the worse 6 months follow-up GOS when an aneurysm was located in the VA group.
Robust Non-Coherent Demodulation Scheme for Bluetooth Voice Transmission Using Linear, Extended, and Unscented Kalman Filtering  [PDF]
Ali S. Alghamdi, Mahdi N. Ali, Mohamed A. Zohdy
Journal of Signal and Information Processing (JSIP) , 2015, DOI: 10.4236/jsip.2015.61002
Abstract: This paper presents a novel and cost effective method to be used in the optimization of the Gaussian Frequency Shift Keying (GFSK) at the receiver of the Bluetooth communication system. The proposed method enhances the performance of the noncoherent demodulation schemes by improving the Bit Error Rate (BER) and Frame Error Rate (FER) outcomes. Linear, Extended, and Unscented Kalman Filters are utilized in this technique. A simulation model, using Simulink, has been created to simulate the Bluetooth voice transmission system with the integrated filters. Results have shown improvements in the BER and FER, and that the Unscented Kalman Filters (UKF) have shown superior performance in comparison to the linear Kalman Filter (KF) and the Extended Kalman Filter (EKF). To the best of our knowledge, this research is the first to propose the usage of the UKF in the optimization of the Bluetooth System receivers in the presence of additive white Gaussian noise (AWGN), as well as interferences.
Analytical Solution for Acoustic Waves Propagation in Fluids  [PDF]
Mohamed I. A. Othman, Mohamed Galal Sayed Ali, Roushdi Mohamed Farouk
World Journal of Mechanics (WJM) , 2011, DOI: 10.4236/wjm.2011.15030
Abstract: This paper presents a mathematical model of linear acoustic wave propagation in fluids. The benefits of a mathematical model over a normal mode analysis are first discussed, then the mathematical model for acoustic propagation in the test medium is developed using computer simulations. The approach is based on a analytical solution to the homogeneous wave equation for fluid medium. A good agreement between the computational presented results with published data.
The Effect of Relaxation Time on the Heat Transfer and Temperature Distribution in Tissues  [PDF]
Mohamed I. A. Othman, Mohamed Galal Sayed Ali, Roushdi Mohamed Farouk
World Journal of Mechanics (WJM) , 2011, DOI: 10.4236/wjm.2011.16035
Abstract: A normal mode analysis for characterizing the temperature fluctuation in tissues was proposed based on the Penne’s bio-heat transfer equation. Closed-form analytical solutions to obtain the heating pattern due to the propagation of ultrasonic waves in tissue system are presented. The evaluation of temporal and spatial distributions of temperature is investigated with the effect of relaxation time. The derived method is evaluated with numerical simulations in 2D which are applied to tissue medium in simplified geometry.
Distances Scale Determination for a Planetary Nebula in Galactic Bulge  [PDF]
Sundus A. Abdullah, Nathera A. Ali, Mohamed A. Sallih
International Journal of Astronomy and Astrophysics (IJAA) , 2013, DOI: 10.4236/ijaa.2013.32008

Planetary Nebulae (PN) distances represent the fundamental parameter for the determination the physical properties of the central star of PN. In this paper the distances scale to Planetary Nebulae in the Galactic bulge were calculated related to previous distances scales. The proposed distance scale was done by recalibrated the previous distance scale technique CKS/D82. This scale limited for nearby PN (D ≤ 3.5 kpc), so the surface fluxes less than other distance scales. With these criteria the results showed that the proposed distance scale is more accurate than other scales related to the observations for adopted sample of PN distances, also the limit of ionized radius (Rio) for all both optically thick and optically thin in the rang of sizes (0.45 > Rio (pc) > 0.03).

Mineral chemistry of monazite-(Nd), xenotime-(Y), apatite, fluorite and zircon hosting in lamprophyre dyke in Abu Rusheid area, South Eastern Desert, Egypt
Mohamed A. Ali
Geologija , 2012,
Abstract: The studied mineralized lamprophyre dyke in Abu Rusheid area is trending NNW-SSE, and occurs withinAbu Rusheid mineralized shear zone, measuring 0.2 - 1.0 m in width and 0.5 - 1.0 km in length. It was emplacedparallel with the Abu Rusheid shear zone. The dyke is mainly composed of plagioclases, amphiboles, mica (musco-vite and biotite), relics of pyroxenes with K-feldspars and quartz derived from surrounding country rocks asphenocrysts embedded in fine-grained groundmass. The lamprophyre dyke hosts REE-minerals monazite-(Nd),xenotime-(Y), and REE-bearing minerals apatite, fluorite, zircon-(Hf), rutile with inclusions of xenotime and ironoxides. The emplacement of lamprophyre dyke caused heating in the mineralized shear zone of Abu Rusheid area.The lamprophyre dyke was subsequently affected by hydrothermal alterations (e.g. chlorite-carbonate, muscovitization,fluoritization).The REE were remobilized from the mineralized shear zones by hydrothermal solutionsand re-precipitatedas REE-minerals xenotime-(Y) and monazite-(Nd) around flourapatite, fluorite, zircon andrutile. The solid solutions between monazite-(Nd) and xenotime-(Y) were formed as a product precipitation fromhydrothermal solutions. Also, the apatite mineral in the lamprophyre dyke was subjected to the heating duringthe emplacement, which lead to its alteration and breakdown with concominant precipitation of xenotime-(Y)and monazite-(Nd). The chemistry of monazite-(Nd) and xenotime-(Y) obtained by scanning electron microscopy(SEM), and electron probe microanalysis (EPMA), showed that these minerals are enriched in U and Th. Themonazite-(Nd) associated with fluorapatite in the studied dyke is poor in Th (0.02 ≤ Th ≤ 0.81 wt%), but usuallyrich in U (0.92 ≤ U ≤ 2.91 wt%), which indicates that monazite formed as a result of flourapatite metasomatism.
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