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Alturki F.A.,King Saud University | Abdelhafiez E.A.,Majmaa University
2012 IEEE 5th International Conference on Advanced Computational Intelligence, ICACI 2012 | Year: 2012

In solving engineering optimization problems, the current Evolutionary Programming (EP) has slow convergence rateson mostproblems, and if thereis more than one local optimum in the problem, theobtained optimal solution may not necessarily be the global optimum. This paper describes a new approach for solving unconstrained optimization problems with either discreteor continuous design variables. The proposed approach is a pattern search method that is based on univariate search hybridized with the Shaking Optimization Algorithm 'SOA'. The computational analysis shows that, for the selected benchmark problems, the proposed approach is a powerful search and optimization technique that may yield better solutions toengineering problems than those obtained using current algorithms for both the solution efficiency and the number of iterations. © 2012 IEEE. Source

El-Mallawany R.,Menoufia University | Gaafar M.S.,National Institute for Standards of Egypt | Gaafar M.S.,Majmaa University | Azzam Y.A.,National Research Institute of Astronomy and Geophysics | Azzam Y.A.,Majmaa University
Chalcogenide Letters | Year: 2014

The deformation potential in x Nb2O5 - (1-x) TeO2, 0.1 PbO - x Nb2O5 - (0.9-x) TeO2 and 0.2 PbO - x Nb2O5 - (0.8-x) TeO2 tellurite glass systems, was calculated using the Central Force Theory (CFT). Analysis of the compositional dependence of the experimental deformation potential in the three glass systems has been achieved. The quantitative analysis was based on the number of oxygen atoms that vibrate in the double well potential, the deformation potential and the mutual potential energy according to (CFT) with longitudinal elongation. Comparisons between the previous measured values and the predicted values using the Artificial Neural Network (ANN) model for 11 different tellurite glass compositions have been implemented which showed good agreement between them. Source

Saddeek Y.B.,Assiut University | El-Mallawany R.,Menoufia University | El-Mallawany R.,Majmaa University | Afifi H.,National Institute for Standards of Egypt
Journal of Non-Crystalline Solids | Year: 2015

The ultrasonic relaxation process of ZnO-TeO2-V2O5 and CeO2-TeO2-V2O5 glasses was investigated in terms of the central force model of acoustically active two-well systems. The theoretical treatment of the vibrations of two-well systems revealed that, the equilibrium interatomic separation, the number of loss centers and the activation energy are affected with the mutual potential energy of the studied glasses. The number of loss centers is related to the compositional dependence of the elastic moduli and the average ring diameter. The results showed that degree of elongation or contraction of the two-well system depends on the concentration of CeO2 or ZnO. The theoretically determined longitudinal and transverse deformation potentials due to the acoustic loss produced by two-well systems decrease with the increase of ZnO/CeO2 content. © 2015 Elsevier B.V. All rights reserved. Source

Gaafar M.S.,National Institute for Standards of Egypt | Gaafar M.S.,Majmaa University | Mahmoud I.S.,Suez Canal University | Mahmoud I.S.,Majmaa University
Journal of Alloys and Compounds | Year: 2016

The longitudinal ultrasonic attenuation in 20Li2O-(80-x) B2O3-xWO3 (0 X 12.5) glass system, was measured using pulse echo technique at ultrasonic frequencies 2, 4, 6 and 14 MHz in the temperature range from 150 to 300 K. The absorption curves showed the presence of well-defined broad peaks at various temperatures depending upon the glass composition and operating frequency. The maximum peaks move to higher temperatures with the increase of operating frequency indicating the presence of some kind of relaxation process. This process has been described as a thermally activated relaxation process which occurs when ultrasonic waves disturb the equilibrium of an atom vibrating in a double-well potential in the glass network structure. Results proved that the average activation energy of the process is mainly depending on the modifier content. This dependence was analyzed in terms of the loss of standard linear solid type, with low dispersion and a broad distribution of Arrhenius type relaxation with temperature independent relaxation strength. The experimental acoustic activation energy has been quantitatively analyzed in terms of the number of loss centers (number of oxygen atoms that vibrate in the double well potential). © 2015 Elsevier B.V. All rights reserved. Source

Saddeek Y.B.,Assiut University | Saddeek Y.B.,Majmaa University
Physica B: Condensed Matter | Year: 2011

Molybdenum lead phosphate glasses doped with La2O3 of the system xMoO35La2O350P2O 5(45-x)PbO, with 0≤x≤25 mol%, have been synthesized and studied by FTIR, ultrasonic and differential scanning calorimetry (DSC) in order to investigate the role of MoO3 content on their atomic structure. The constants of elasticity and Debye temperatures of the glasses have been investigated using sound velocity measurements at 4 MHz. According to the IR analysis, the vibrations of the phosphate structural units are shifted towards higher wavenumbers associated with the formation of bridging oxygens. The change in density with MoO3 content reveals that the molybdate units are less dense than the lead units. The observed compositional dependence of the constants of elasticity is interpreted in terms of the effect of MoO3 on the different phosphate bonds. It is assumed that MoO3 plays the role of a former by increasing the ultrasonic velocity and the constants of elasticity of the phosphate glasses. © 2010 Elsevier B.V. All rights reserved. Source

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