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Search Results: 1 - 10 of 1105 matches for " Hamed Shahmohamadi "
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A Series Solution for Three-Dimensional Navier-Stokes Equations of Flow near an Infinite Rotating Disk  [PDF]
Hamed Shahmohamadi, Mahdi Mohammadpour
World Journal of Mechanics (WJM) , 2014, DOI: 10.4236/wjm.2014.45014
Abstract:

In this paper, homotopy analysis method (HAM) and Padé approximant will be considered for finding analytical solution of three-dimensional viscous flow near an infinite rotating disk which is a well-known classical problem in fluid mechanics. The solution is compared to the numerical (fourth-order Runge-Kutta) solution and the convergence of the obtained series solution is carefully analyzed. The results illustrate that HAM-Padé is an appropriate method in solving the systems of nonlinear equations.

A Novel Solution for the Glauert-Jet Problem by Variational Iteration Method-Padé Approximant
Hamed Shahmohamadi,Mohammad Mehdi Rashidi
Mathematical Problems in Engineering , 2010, DOI: 10.1155/2010/501476
Abstract: We will consider variational iteration method (VIM) and Padé approximant, for finding analytical solutions of the Glauert-jet (self-similar wall jet over an impermeable, resting plane surface) problem. The solutions are compared with the exact solution. The results illustrate that VIM is an attractive method in solving the systems of nonlinear equations. It is predicted that VIM can have a found wide application in engineering problems.
New Solution for Steady Flow over a Rotating Disk in Porous Medium with Heat Transfer
Hamed Shahmohamadi,Mohammad Mehdi Rashidi
Progress in Applied Mathematics , 2011,
Abstract: The purpose of this study is to implement a new analytical method which is a combination of the variational iteration method (VIM) and the Padé approximant for solving steady flow over a rotating disk in porous medium with heat transfer. The velocity and temperature profiles are shown also the influence of the porosity parameter on them is discussed in detail. The solution is compared with the numerical solution. Comparisons between the VIM-Padé and the numerical solution reveal that the new technique is a promising tool for solving the above problem. It is predicted that the VIM–Padé can have wide application in engineering problems (especially for boundary-layer and natural convection problems). Key Words: Variational Iteration Method; Padé Approximant; Rotating Disk; Heat Transfer
Analytic Approximate Solutions for Unsteady Two-Dimensional and Axisymmetric Squeezing Flows between Parallel Plates
Mohammad Mehdi Rashidi,Hamed Shahmohamadi,Saeed Dinarvand
Mathematical Problems in Engineering , 2008, DOI: 10.1155/2008/935095
Abstract: The flow of a viscous incompressible fluid between two parallel plates due to the normal motion of the plates is investigated. The unsteady Navier-Stokes equations are reduced to a nonlinear fourth-order differential equation by using similarity solutions. Homotopy analysis method (HAM) is used to solve this nonlinear equation analytically. The convergence of the obtained series solution is carefully analyzed. The validity of our solutions is verified by the numerical results obtained by fourth-order Runge-Kutta.
Stability Analysis of Barley (Hordeum vulgare L.) Genotypes in Regional Trials in Cold Zone
M. Shahmohamadi,H. Dehghani,A. Yousefi
Journal of Science and Technology of Agriculture and Natural Resources , 2005,
Abstract: To determine yield stability and to evaluate genotype interaction with environment interaction, 18 genotype of barley (Hordeum vulgare L.) and a control group were evaluated in a randomized complete block design with 4 replications in 3 successive years (1997-2000) at 10 research stations. Simple and combined analysis of variance revealed significant genetic differences between yield genotypes for grain yield. The results of combined analysis of variance indicated that genotypic and genotype were significant through interaction with environment. Therefore, different stability parameters including, environmental variance (S2i), environmental coefficient of variation (C.Vi), mean of variance of interaction (θi), interaction variance (θi), equivalence ( W2i), stability variance (σ2i), linear regression coefficient (bi, βi), mean of squares of deviation from regression (S2 di) and years within location MS for a genotype, averaging over all locations (MSy/l) were determined. Based on all the stability parameters, genotype 18 was known as the most stable one and genotypes 17 and 11 ranked lower. Genotype 5 with the highest yield was known to be the most adaptable one at fertile environments and is recommended for these locations. In addition, genotype 9 with good yield and low yield variance (1.58) and regression coefficient of less than 1 is suggested for unfertile locations.
XUV and Soft X-Ray Laser Radiation from Ni-Like Au  [PDF]
Wessameldin S. Abdelaziz, Hamed Mahmoud Hamed Ibrahim
Optics and Photonics Journal (OPJ) , 2011, DOI: 10.4236/opj.2011.13019
Abstract: Atomic structure data and effective collision strengths from literature for 1s2 2s2 2p6 3s2 3p63d10 and 34 fine-structure levels contained in the configurations 1s2 2s2 2p6 3s2 3p63d9 4l (l = s, p, d) for the nickel-like Au ion are used in the determination of the reduced population for these levels over a wide range of electron densities and at various electron plasma temperatures. The gain coefficient for those transitions with positive population inversion factor are determined and plotted against the electron density.
Computer Generated Quadratic and Higher Order Apertures and Its Application on Numerical Speckle Images  [PDF]
Abdallah Mohamed Hamed
Optics and Photonics Journal (OPJ) , 2011, DOI: 10.4236/opj.2011.12007
Abstract: A computer generated quadratic and higher order apertures are constructed and the corresponding numerical speckle images are obtained. Secondly, the numerical images of the autocorrelation intensity of the randomly distributed object modulated by the apertures and the corresponding profiles are obtained. Finally, the point spread function (PSF) is computed for the described modulated apertures in order to improve the resolution.
Scanning Holography Using a Modulated Linear Pupil: Simulations  [PDF]
Abdallah Mohamed Hamed
Optics and Photonics Journal (OPJ) , 2011, DOI: 10.4236/opj.2011.12008
Abstract: In this paper an electron microscopic image of diameter 80 – 120 nm and of dimensions 180×220 pixels is used as a test object to fabricate Fresnel zone plate hologram. The author proposes a different set of pupils: one pupil still being a delta function and the other being a function of < r > = sqrt(x2+y2). The obtained reconstructed images in case of scanning holography are investigated.
Recognition of Direction of New Apertures from the Elongated Speckle Images: Simulation  [PDF]
Abdallah Mohamed Hamed
Optics and Photonics Journal (OPJ) , 2013, DOI: 10.4236/opj.2013.33040
Abstract:

In this paper, we present an elongated speckle images produced from diffusers using sharp elliptical apertures. The orientation of the elliptic aperture is recognized from the direction of the elongation in the speckle images. The aperture tilting out of the plane is investigated. Three models of elliptical apertures are considered and the corresponding speckle images are obtained. The 1st model is composed of two orthogonal ellipses or plus symbol pupil; the 2nd has four symmetric ellipses with an angle of 45° between each of them or in the form of a snow flake pupil and the 3rd model looks like an airplane. Also, the autocorrelation profiles of the speckle images corresponding to the diffused airplane are obtained from which the average speckle size is computed. Finally, the reconstructed images of the described elliptical models and its autocorrelation images, making use of Mat lab code, are obtained.

Can Macroinvertebrate Assemblage Changes Be Used as Biological Indicator of Water Quality of the Nokoue Lake (Benin)?  [PDF]
Hamed Odountan, Youssouf Abou
Journal of Environmental Protection (JEP) , 2015, DOI: 10.4236/jep.2015.612122
Abstract: Investigations on biological capacity of water quality of macroinvertebrate community are very uncommon, and such as the amount of information available on the Nokoue Lake (the largest lake of Benin) is very limited. This information gap needs to be filled for better management of the Nokoue Lake. The goal of this study was to evaluate the possibility of using the macroinvertebrate community structures in Nokoue Lake and the environmental factors responsible for the maintenance of these structures. Nokoue Lake was studied over three months, during high flood period in which time subsurface water and macroinvertebrate samples were collected and analyzed. A study showed that the macroinvertebrate assemblages was done according to ecological gradients as pH, conductivity, TDS, salinity, chlorophyll a and probably to anthropogenic actions (nutriments). Better than the percentage of insects, the percentage of Chironomidae informed very well about macroinvertebrate assemblages. To assess the biological health of the environment, the Family Biotic Index (FBI) turns out to be more appropriate than diversity indices that do not take into account the intermediate pollution. Organic pollution revealed by the FBI probably affects the aquatic life.
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