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Marey M.,Menoufia University | Samir M.,El Shorouk Academy | Ahmed M.H.,Memorial University of Newfoundland
IEEE Transactions on Vehicular Technology | Year: 2013

The application of multiple transmit antennas in orthogonal frequency-division multiplexing (OFDM) systems provides better spectral efficiency with high performance gain. However, these systems are very sensitive to channel estimation errors and analog front-end impairments, such as in-phase/quadrature-phase (IQ) imbalance. To ensure a reliable transmission, the channel impulse response (CIR) and IQ imbalance have to be accurately estimated. Unlike previous work, we show that the unwanted IQ imbalance can be exploited to achieve a diversity gain. This paper develops a maximum-likelihood (ML) detector by exploiting the diversity gain resulting from the IQ imbalance for Alamouti space-time block code OFDM systems. Moreover, we propose a novel iterative algorithm to jointly estimate the CIR and IQ imbalance occurring at both the transmitter and the receiver. We initially employ a pilot sequence for estimation and detection. Then, we exploit the soft information provided by the detector via an expectation-maximization (EM) algorithm to improve the estimation efficiency iteratively. To reduce the computational complexity of the estimation process, a suboptimal algorithm is also developed. Simulation results indicate that the bit-error-rate (BER) performance of the proposed detector in conjunction with the proposed estimation algorithms is very close to the BER of the perfectly known parameters case with a diversity gain resulting from the IQ imbalance. © 1967-2012 IEEE.

Marey M.,Memorial University of Newfoundland | Samir M.,El Shorouk Academy | Dobre O.A.,Memorial University of Newfoundland
IEEE Transactions on Broadcasting | Year: 2012

The imbalances between the In-phase (I) and Quadrature-phase (Q) branches represent a significant source of impairment in the orthogonal frequency division multiplexing (OFDM) systems. Recently, it has been shown that the unwanted IQ imbalances can be actually exploited to achieve a diversity gain. In this contribution, by taking into account the diversity gain resulting from the IQ imbalances, we develop a novel algorithm to jointly estimate the channel impulse response and IQ imbalances occurring at both the transmitter and receiver. Starting from the Maximum Likelihood (ML) principle, we derive an estimation algorithm based on the expectation maximization (EM) algorithm, which exploits information from the pilot symbols and detected data symbols in a systematic fashion. To reduce the complexity of the estimation algorithm, a sub-optimal scheme is also introduced. The results indicate that the proposed algorithms achieve a significant improvement in the bit error rate (BER) performance after three iterations as compared to conventional data-aided algorithms. © 2011 IEEE.

Ahmed H.M.,El Shorouk Academy
IMA Journal of Mathematical Control and Information | Year: 2015

In this paper, the controllability result of impulsive neutral stochastic functional differential equations with finite delay and fractional Brownian motion in a Hilbert space is studied. By using Banach's fixed point theorem, sufficient conditions are given for the controllability of the system. Finally, an example is given to illustrate the application of our result. © The authors 2014. Published by Oxford University Press on behalf of the Institute of Mathematics and its Applications. All rights reserved.

Ahmed H.M.,El Shorouk Academy
Cogent Engineering | Year: 2016

By using the strongly continuous semigroup theory and the Banach contraction principle, we study the boundary controllability of time varying delay impulsive nonlinear fractional integrodifferential system in Banach spaces. An example is provided to illustrate the theory. © 2016 The Author(s).

Deifalla A.,El Shorouk Academy | Ghobarah A.,McMaster University
Journal of Composites for Construction | Year: 2010

Torsion failure is an undesirable brittle form of failure. Although previous experimental studies have shown that using fiber-reinforced polymer (FRP) sheets for torsion strengthening of reinforced concrete (RC) beams is an effective solution in many situations, very few analytical models are available for predicting the section capacity. None of these models predicted the full behavior of RC beams wrapped with FRP, account for the fact that the FRP is not bonded to all beam faces, or predicted the ultimate FRP strain using equations developed based on testing FRP strengthened beams in torsion. In this paper, an analytical model was developed for the case of the RC beams strengthened in torsion. The model is based on the basics of the modified compression field theory, the hollow tube analogy, and the compatibility at the corner of the cross section. Several modifications were implemented to be able to take into account the effect of various parameters including various strengthening schemes where the FRP is not bonded to all beam faces, FRP contribution, and different failure modes. The model showed good agreement with the experimental results. The model predicted the strength more accurately than a previous model, which will be discussed later. The model predicted the FRP strain and the failure mode. © 2010 ASCE.

Deifalla A.,El Shorouk Academy | Ghobarah A.,McMaster University
Journal of Composites for Construction | Year: 2010

In several cases of loading and geometrical configurations, flexure beams, and girders are subjected to combined shear and torsion. Failure of a structural element under combined shear and torsion is brittle in nature. Externally bonded fiber-reinforced polymer (FRP) fabrics are currently being studied and used for the rehabilitation, repair, and retrofit of concrete structure. The objective of this study is to investigate the strengthening techniques for T-beams subjected to combined shear and torsion. Six half-scale beams-two control specimen and four strengthened beams-were constructed and tested using a specially designed test setup that subjects the beam to combined shear and torsion with different ratios. Four strengthening techniques using carbon FRPs were tested. The experimental results were reported and analyzed to assess the effectiveness of the proposed strengthening techniques. An innovative strengthening technique namely the extended U-jacket showed promising results in terms of strength and ductility while being quite feasible for strengthening. Future areas of research are being outlined. © 2010 ASCE.

Improving the efficiency and convergence rate of the Multilayer Backpropagation Neural Network Algorithms is an active area of research. The last years have witnessed an increasing attention to entropy based criteria in adaptive systems. Several principles were proposed based on the maximization or minimization of entropic cost functions. One way of entropy criteria in learning systems is to minimize the entropy of the error between two variables: typically one is the output of the learning system and the other is the target. In this paper, improving the efficiency and convergence rate of Multilayer Backpropagation (BP) Neural Networks was proposed. The usual Mean Square Error (MSE) minimization principle is substituted by the minimization of Shannon Entropy (SE) of the differences between the multilayer perceptions output and the desired target. These two cost functions are studied, analyzed and tested with two different activation functions namely, the Cauchy and the hyperbolic tangent activation functions. The comparative approach indicates that the Degree of convergence using Shannon Entropy cost function is higher than its counterpart using MSE and that MSE speeds the convergence than Shannon Entropy. © 2011 Faculty of Computers and Information, Cairo University. Production and hosting by Elsevier B.V. All rights reserved.

El-Wakeel A.S.,Military Technical College | Ellissy A.E.-E.K.M.,El Shorouk Academy | Abdel-Hamed A.M.,El Shorouk Academy
Electric Power Components and Systems | Year: 2015

The proportional-integral-derivative controllers were the most popular controllers of this century because of their remarkable effectiveness, and simplicity of implementation. However, proportional-integral-derivative controllers are usually poorly tuned in practice. This article presents a hybrid particle swarm optimization and bacterial foraging techniques for determining the optimal parameters of a proportional-integral-derivative controller for speed control of a permanent magnet brushless DC motor. The first part of the article deals with the system modeling and its verification where a model of modest accuracy cannot be expected to give a fair comparison of different controllers. The remaining parts of the article present the application of different optimization techniques to tune the proportional-integral-derivative controller as applied to the motor model. The particle swarm optimization, bacterial foraging, and bacterial foraging-particle swarm optimization algorithms are implemented in MATLAB while the GA Toolbox is used. The performance of the tuned controllers is simulated and experimentally verified to evaluate the main characteristics of each one. It is found that the proposed hybrid bacterial foraging-particle swarm optimization technique is more efficient in improving the step response characteristics and achieving the desired performance indices. © 2015 Taylor and Francis Group, LLC.

Tolba M.M.,El Shorouk Academy
WIT Transactions on Ecology and the Environment | Year: 2014

Talks over the past decade have been concerned with achieving a more sustainable form of tourism; however, the problem is that the largest sector of tourism is that of mass tourism, which continues to be the worst form of tourism in terms of sustainability. Previous studies have focused on defining the term ‘sustainable tourism’. However, these studies have not been able to agree on a single definition for the term, which has dozens of definitions. This research aims to discuss and analyze the concept of ‘sustainable mass tourism’ and its effects on the Nabq protected area. In addition, this research aims to focus on mass tourism in terms of three separate aspects for its development, which are: economic sustainability, social sustainability and environmental sustainability. Each of these aspects will be discussed separately. By dividing the concept into three different parts, each part will be studied so as to relate to or isolate from each other to determine the safest and most successful path to be used by developers of mass tourism with the aim of applying the results of this research to the Nabq protected area. © 2014 WIT Press.

Tawfik M.,El Shorouk Academy
International Journal of Sustainable Development and Planning | Year: 2016

The objective of this study is to present a coherent theoretical framework to deepen the essence of sustainable design and to reach an explanation for its constituent components in the environment of a protected area. This study examines the physical changes of protected areas and the acts of improvement made so that there will be fewer damages to the local environment. Reaching a sustainable framework would contribute to the protection of these areas and the environment in general. To achieve this objective, the ideas of 'sustainable development' and 'sustainable ecotourism' have been studied. The next step is concerned with the outcome of these studies; in addition a model called 'sustainable design to Locator' has been recommended to set up a theoretical framework for the main items in the design of a sustainable protected area. The final step is the fundamental assumptions, strategies and plans related to the subject; qualitative results based on functional, environmental, experimental and aesthetic items have been reached. © 2016 WIT Press,

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