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Search Results: 1 - 10 of 8900 matches for " Mohamed Medhat "
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Synthesis of Chained Achromatic Layer Systems Forming Controlled Low Transmittance Bands  [PDF]
Mohamed Medhat, Samy S. Farag
Optics and Photonics Journal (OPJ) , 2011, DOI: 10.4236/opj.2011.13021
Abstract: The approach utilized in the design of achromatic periods formed of two layers a high-index and a low-index is developed by combining the first two periods together. These two periods are therefore reduced to three layers a central one, an upper layer and a lower layer. Both the upper and lower layers are matched to the central at two different wavelengths. This forms the so called a combined achromatic period or the basic unit. Multilayers showing low transmittance bands are then synthesized of this basic unit. Parameters used in the synthesis of such multilayers are pointed out and their control role is investigated.
The Characteristic Function Method and Its Application to (1 + 1)-Dimensional Dispersive Long Wave Equation  [PDF]
Medhat M. Helal, Mohammad L. Mekky, Emad A. Mohamed
Applied Mathematics (AM) , 2012, DOI: 10.4236/am.2012.31002
Abstract: In this paper, the characteristic function method is applied to seek traveling wave solutions of nonlinear partial differential equations in a unified way. We consider the Wu-Zhang equation (which describes (1 + 1)-dimensional disper-sive long wave). The equations governing the wave propagation consist of a pair of non linear partial differential equations. The characteristic function method reduces the system of nonlinear partial differential equations to a system of nonlinear ordinary differential equations which is solved via the shooting method, coupled with Rungekutta scheme. The results include kink-profile solitary wave solutions, periodic wave solutions and rational solutions. As an illustrative example, the properties of some soliton solutions for Wu-Zhang equation are shown by some figures.
A Similarity Technique for Solving Two-Layer Shallow-Water Equations  [PDF]
Magda M. Kassem, Medhat M. Helal, Mohammad L. Mekky, Emad A. Mohamed
Applied Mathematics (AM) , 2012, DOI: 10.4236/am.2012.34047
Abstract: This paper is devoted to the analysis of the two-layer shallow-water equations representing gravity currents. A similarity technique which is the characteristic function method is applied for this study. The application of the characteristic function method makes it possible to obtain the similarity forms depending on a group of infinitesimal transformations. Thus, the number of independent variables is reduced by one and the governing partial differential equations with the auxiliary conditions reduce to a system of ordinary differential equations with the appropriate auxiliary conditions. Numeric solutions are presented and discussed.
Diagnostic Value of Immunoglobulin A and M antibodies as a disease Marker for hepatitis A Infection
Medhat Haroun,,Mohamed M. El-Sayed
Türk Biyokimya Dergisi , 2007,
Abstract: This study was conducted to assess the effect of anti-immunoglobulin antibodies onthe measurement of the humoral immune response in hepatitis A virus (HAV) infectedpatients. Serum samples from 47 patients with acute hepatitis A and from 47 age/sexmatched healthy adult subjects were tested for IgA, IgG and IgM by ELISA. Antiimmunoglobulinantibodies were defined using goat immunoglobulins as a target tocharacterize distinct changes in levels of interacting immunoglobulins. Initial resultsobtained before removal of antibodies that interacted with goat immunoglobulinssuggested that HAV patients had increased levels of IgA and IgM in their sera. It wasfound that normal individuals had mean IgA, IgG and IgM levels of 2.52 ± 0.22 mg/ml,9.86 ± 0.94 mg/ml and 1.75 ± 0.13 mg/ml, respectively while HAV patients had meanlevels of 2.89 ± 0.20 mg/ml, 10.03 ± 1.05 mg/ml and 1.97 ± 0.13 mg/ml (p <0.0002, p<0.41 and p <0.0001). However, the mean levels of IgA and IgM in HAV infected sera,after purification from antibodies that interacted with goat immunoglobulins, were 2.49± 0.21 mg/ml and 1.73 ± 0.14 mg/ml. Therefore, there was no significant difference inHAV patients compared to normal individuals (p <0.55 and p <0.56). The presence ofcirculating immune complex in serum during the early phase of infection may contributeto immunopathological effects in the infected host and provide some new insights intoantibody response to HAV
Hybrid Algorithm for Multiprocessor Task Scheduling
Mostafa R Mohamed,Medhat H A Awadalla
International Journal of Computer Science Issues , 2011,
Abstract: Multiprocessors have become powerful computing means for running real-time applications and their high performance depends greatly on parallel and distributed network environment system. Consequently, several methods have been developed to optimally tackle the multiprocessor task scheduling problem which is called NP-hard problem. To address this issue, this paper presents two approaches, Modified List Scheduling Heuristic (MLSH) and hybrid approach composed of Genetic Algorithm (GA) and MLSH for task scheduling in multiprocessor system. Furthermore, this paper proposes three different representations for the chromosomes of genetic algorithm: task list (TL), processor list (PL) and combination of both (TLPLC). Intensive simulation experiments have been conducted on different random and real-world application graphs such as Gauss-Jordan, LU decomposition, Gaussian elimination and Laplace equation solver problems. Comparisons have been done with the most related algorithms like: list scheduling heuristics algorithm LSHs, Bipartite GA (BGA) [1] and Priority based Multi-Chromosome (PMC) [2]. The achieved results show that the proposed approaches significantly surpass the other approaches in terms of task execution time (makespan) and processor efficiency.
On a new hypergeometric transformation
Medhat A. Rakha,Mohamed M. Awad
Journal of Interpolation and Approximation in Scientific Computing , 2012, DOI: 10.5899/2012/jiasc-00008
Abstract: The aim of this article is to establish a general transformation for generalized hypergeometric function involving hypergeometric polynomials, by the method of elementary manipulation of series representation and to derive certain Chaundy's formulae by another method. Two applications are presented; Watson's theorem on the sum of $_3F_{2}$ and their contiguous summation formulae are deduced by means of the generalized Gauss' second summation theorem. Also several earlier results by Driver - Johnston and Coffey - Johnston follow as special cases of our main findings.
Experimental Investigation of Intake Diesel Aerosol Fuel Homogeneous Charge Compression Ignition (HCCI) Engine Combustion and Emissions  [PDF]
Medhat Elkelawy
Energy and Power Engineering (EPE) , 2014, DOI: 10.4236/epe.2014.614045
Abstract: External mixture formation (PFI) of a diesel fuel aerosol has employed to investigate the diesel HCCI engine combustion and emissions characteristics. The key to the external mixture formation with diesel fuel is the proper fuel/air mixture preparation. A proposed intake diesel fuel aerosol system mainly consists of a small chamber, in which the diesel fuel is fully vaporized by means of fuel cavitation inside the diesel injector nozzle. Nozzle cavitation is mainly affected by the injection pressure and the fuel system temperature. Results obtained reveal that the proposed method determines the possibility of producing a complete homogeneous fuel/air mixture, which can be applied to the diesel HCCI engine. With this method, the combustion and emission behavior were entirely optimized and the engine is capable of running in HCCI combustion mode with nearly ideal mixture preparation. In the present investigation, a methodology for the HCCI combustion mode of the diesel aerosol/air mixtures based on the fuel cavitation inside the injector nozzle parameters (such as the injection pressure and the fuel system temperature where fuel premixed ratio, NOx, CO, CO2, and HC emissions) have analyzed. Based on the engine performance and emissions characteristics the fuel injection pressure and the fuel system temperature have optimized to produce a suitable fuel premixed ratio and the perfect fuel/air mixture homogeneity at different engine operating conditions. The optimal injection pressure ranges between 150 - 200 bars, while the fuel system temperature lies within 175 - 200. Loops of exhaust gas recirculation (EGR) are used to extend the engine load by controlling the combustion phasing.
Infantile Hemangiopericytoma: Two Cases Report and Literature Review  [PDF]
Gamal Al-Saied, Amin Abokifa, Mohamed Al-Saeed, Mohamed Abdul Aziz, Tharwat Hussain, Medhat Ibrahim, Moemen Hafez, Dalal Nemenqani, Naglaa Fawzy, Mohamed Shahin
Surgical Science (SS) , 2011, DOI: 10.4236/ss.2011.27083
Abstract: Hemangiopericytoma is a rare vascular tumour of infants. Although generally considered to be benign, local recurrence and metastases can occur. Herein, we report on two full term girls, delivered with lumbosacral swelling and left thigh swelling respectively. Complete surgical excision with safety margins was performed for each lesion. Histologic examination of both lesions showed picture of infantile hemangiopericytoma. There is no evidence of local recurrence or distant metastasis during last 20 and 17 months for 1st case and 2nd case respectively. In conclusion; most infantile hemangiopericytoma follow a benign course. Rarely these tumours behave aggressively with local infiltration, recurrences and even distant metastases. Careful follow up is therefore essential.
Energy-Aware Task Partitioning on Heterogeneous Multiprocessor Platforms
Elsayed Saad,Medhat Awadalla,Mohamed Shalan,Abdullah Elewi
International Journal of Computer Science Issues , 2012,
Abstract: Efficient task partitioning plays a crucial role in achieving high performance at multiprocessor platforms. This paper addresses the problem of energy-aware static partitioning of periodic realtime tasks on heterogeneous multiprocessor platforms. A Particle Swarm Optimization variant based on Min-min technique for task partitioning is proposed. The proposed approach aims to minimize the overall energy consumption, meanwhile avoid deadline violations. An energy-aware cost function is proposed to be considered in the proposed approach. Extensive simulations and comparisons are conducted in order to validate the effectiveness of the proposed technique. The achieved results demonstrate that the proposed partitioning scheme significantly surpasses previous approaches in terms of both number of iterations and energy savings.
Energy-Aware Task Partitioning on Heterogeneous Multiprocessor Platforms
Elsayed Saad,Medhat Awadalla,Mohamed Shalan,Abdullah Elewi
Computer Science , 2012,
Abstract: Efficient task partitioning plays a crucial role in achieving high performance at multiprocessor plat forms. This paper addresses the problem of energy-aware static partitioning of periodic real-time tasks on heterogeneous multiprocessor platforms. A Particle Swarm Optimization variant based on Min-min technique for task partitioning is proposed. The proposed approach aims to minimize the overall energy consumption, meanwhile avoid deadline violations. An energy-aware cost function is proposed to be considered in the proposed approach. Extensive simulations and comparisons are conducted in order to validate the effectiveness of the proposed technique. The achieved results demonstrate that the proposed partitioning scheme significantly surpasses previous approaches in terms of both number of iterations and energy savings.
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