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3 results on '"Lotfi, Abdelhakim"'

1. Domain Decomposition Method with an Interface Preconditioner for Frictionless Contact Problem.

Author

Lotfi, Abdelhakim

Subjects
*INVISCID flow, *FINITE element method, *SCHUR complement, *ELASTICITY, *ALGORITHMS, *STRENGTH of materials
Abstract

The present paper is concerned with the frictionless bilateral or unilateral contact problem between two elastic bodies. An algorithm is introduced to solve the resulting finite element system by a non-overlapping domain decomposition method. This technique enable us to transform the solution of the global problem to the solutions of the elasticity equations for each body separately and the solution of the Schur complement problem on the contact surface. The main goal of this work is the construction of the interface preconditioner for the Schur complement problem. The solution is obtained by using a successive approximation method. Finally, some numerical results of the proposed method are given. [ABSTRACT FROM AUTHOR]

Published
2008
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2. Numerical Method for Computer Generated Hologram.

Author

Lotfi, Abdelhakim

Subjects
*HOLOGRAPHY, *MATHEMATICAL analysis, *FOURIER analysis, *HELMHOLTZ equation, *FINITE differences
Abstract

The main purpose of this article is to develop a program package which generates artificial holograms by numerical methods and these computer generated holograms are numerically reconstructed. For the calculation of light propagation needed in the generation of holograms or in the reconstruction of the object from the hologram, we use two strategies, the first is the Fourier-based algorithm and the second uses finite difference discretization, and numerical tests that assess the accuracy of these algorithms are presented. [ABSTRACT FROM AUTHOR]

Published
2007
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3. Numerical Analysis of Heat Transfer for Cooling of Photovoltaic Cells.

Author

Lotfi, Abdelhakim

Subjects
*HEAT transfer, *NUMERICAL analysis, *ELECTRICITY, *PHOTOVOLTAIC cells, *PHOTOELECTRIC cells
Abstract

Photovoltaic cells are devices which convert solar radiation directly into electricity. However, solar radiation increases the photovoltaic cells temperature [1] [2]. The temperature has an influence on the degradation of the cell efficiency and the lifetime of a PV cell. This work reports on a cooling water technique for cells, whereby the cooling system was placed at the front surface of the cells to dissipate away excess heat and to block unwanted radiation. Using water as a cooling medium for the cells, the overheating of closed panel is greatly reduced without prejudicing luminosity and water acts as a filter to remove a portion of solar spectrum in the infrared band but allows transmission of the visible spectrum most useful for the PV operation. The aims of this study are to develop a 3D thermal model to simulate the cooling and heat transfer in Photovoltaic panel and recommend a cooling technique for the PV panel. In order to have a good estimation for the temperature distribution, the three-dimensional flow and heat transfer across the cooling block is investigated numerically by solving the continuity, momentum and energy equations using FLUENT. The second objective of this work is to study the influence of the geometrical dimensions of the panel, water mass flow rate and water inlet temperature on the flow distribution and the solar panel temperature. The results obtained by the model are compared with experimental results from testing the prototype of the cooling device. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Published
2014
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