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Hamouda, Noureddine,Benalla, Hocine,Hemsas, Kameleddine,Babes, Badreddine,Petzoldt, Jurgen,Ellinger, Thomas,Hamouda, Cherif The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.6
This paper proposes a real-time implementation of an optimal operation of a double stage grid connected wind power system incorporating an active power filter (APF). The system is used to supply the nonlinear loads with harmonics and reactive power compensation. On the generator side, a new adaptive neuro fuzzy inference system (ANFIS) based maximum power point tracking (MPPT) control is proposed to track the maximum wind power point regardless of wind speed fluctuations. Whereas on the grid side, a modified predictive current control (PCC) algorithm is used to control the APF, and allow to ensure both compensating harmonic currents and injecting the generated power into the grid. Also a type 2 fuzzy logic controller is used to control the DC-link capacitor in order to improve the dynamic response of the APF, and to ensure a well-smoothed DC-Link capacitor voltage. The gained benefits from these proposed control algorithms are the main contribution in this work. The proposed control scheme is implemented on a small-scale wind energy conversion system (WECS) controlled by a dSPACE 1104 card. Experimental results show that the proposed T2FLC maintains the DC-Link capacitor voltage within the limit for injecting the power into the grid. In addition, the PCC of the APF guarantees a flexible settlement of real power exchanges from the WECS to the grid with a high power factor operation.
Existence and Regularity Results for the Inviscid Primitive Equations with Lateral Periodicity
Hamouda, M.,Jung, C. Y.,Temam, R. Springer Science + Business Media 2016 Applied mathematics and optimization Vol.73 No.3
<P>The article is devoted to prove the existence and regularity of the solutions of the 3D inviscid Linearized Primitive Equations (LPEs) in a channel with lateral periodicity. This was assumed in a previous work (Hamouda et al. in Discret Contin Dyn Syst Ser S 6(2):401-422, 2013) which is concerned with the boundary layers generated by the corresponding viscous problem. Although the equations under investigation here are of hyperbolic type, the standard methods do not apply because of the specificity of the hyperbolic system. A set of non-local boundary conditions for the inviscid LPEs has to be imposed at the lateral boundary of the channel making thus the system well-posed.</P>
Noureddine Hamouda,Hocine Benalla,Kameleddine Hemsas,Badreddine Babes,Jurgen Petzoldt,Thomas Ellinger,Cherif Hamouda 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.6
This paper proposes a real-time implementation of an optimal operation of a double stage grid connected wind power system incorporating an active power filter (APF). The system is used to supply the nonlinear loads with harmonics and reactive power compensation. On the generator side, a new adaptive neuro fuzzy inference system (ANFIS) based maximum power point tracking (MPPT) control is proposed to track the maximum wind power point regardless of wind speed fluctuations. Whereas on the grid side, a modified predictive current control (PCC) algorithm is used to control the APF, and allow to ensure both compensating harmonic currents and injecting the generated power into the grid. Also a type 2 fuzzy logic controller is used to control the DC-link capacitor in order to improve the dynamic response of the APF, and to ensure a well-smoothed DC-Link capacitor voltage. The gained benefits from these proposed control algorithms are the main contribution in this work. The proposed control scheme is implemented on a small-scale wind energy conversion system (WECS) controlled by a dSPACE 1104 card. Experimental results show that the proposed T2FLC maintains the DC-Link capacitor voltage within the limit for injecting the power into the grid. In addition, the PCC of the APF guarantees a flexible settlement of real power exchanges from the WECS to the grid with a high power factor operation.
Performance of Convolutionally-Coded MIMO Systems with Antenna Selection
Hamouda Walaa,Ghrayeb Ali The Korea Institute of Information and Commucation 2005 Journal of communications and networks Vol.7 No.3
In this work, we study the performance of a serial concatenated scheme comprising a convolutional code (CC) and an orthogonal space-time block code (STBC) separated by an inter-leaver. Specifically, we derive performance bounds for this concatenated scheme, clearly quantify the impact of using a CC in conjunction with a STBC, and compare that to using a STBC code only. Furthermore, we examine the impact of performing antenna selection at the receiver on the diversity order and coding gain of the system. In performing antenna selection, we adopt a selection criterion that is based on maximizing the instantaneous signal-tonoise ratio (SNR) at the receiver. That is, we select a subset of the available receive antennas that maximizes the received SNR. Two channel models are considered in this study: Fast fading and quasi-static fading. For both cases, our analyses show that substantial coding gains can be achieved, which is confirmed through Monte-Carlo simulations. We demonstrate that the spatial diversity is maintained for all cases, whereas the coding gain deteriorates by no more than $10\;log_{10}$ (M / L) dB, all relative to the full complexity multiple-input multiple-output (MIMO) system.
A BLMS Adaptive Receiver for Direct-Sequence Code Division Multiple Access Systems
Hamouda Walaa,McLane Peter J. The Korea Institute of Information and Commucation 2005 Journal of communications and networks Vol.7 No.3
We propose an efficient block least-mean-square (BLMS) adaptive algorithm, in conjunction with error control coding, for direct-sequence code division multiple access (DS-CDMA) systems. The proposed adaptive receiver incorporates decision feedback detection and channel encoding in order to improve the performance of the standard LMS algorithm in convolutionally coded systems. The BLMS algorithm involves two modes of operation: (i) The training mode where an uncoded training sequence is used for initial filter tap-weights adaptation, and (ii) the decision-directed where the filter weights are adapted, using the BLMS algorithm, after decoding/encoding operation. It is shown that the proposed adaptive receiver structure is able to compensate for the signal-tonoise ratio (SNR) loss incurred due to the switching from uncoded training mode to coded decision-directed mode. Our results show that by using the proposed adaptive receiver (with decision feedback block adaptation) one can achieve a much better performance than both the coded LMS with no decision feedback employed. The convergence behavior of the proposed BLMS receiver is simulated and compared to the standard LMS with and without channel coding. We also examine the steady-state bit-error rate (BER) performance of the proposed adaptive BLMS and standard LMS, both with convolutional coding, where we show that the former is more superior than the latter especially at large SNRs ($SNR\;\geq\;9\;dB$).
Error Control Coding and Space-Time MMSE Multiuser Detection in DS-CDMA Systems
Hamouda, Walaa,McLane, Peter J. The Korea Institute of Information and Commucation 2003 Journal of communications and networks Vol.5 No.3
We consider the use of error control coding in direct sequence-code-division multiple access (OS-COMA) systems that employ multiuser detection (MUO) and space diversity. The relative performance gain between Reed-Solomon (RS) code and convolutional code (CC) is well known in [1] for the single user, additive white Gaussian noise (AWGN) channel. In this case, RS codes outperform CC's at high signal-to-noise ratios. We find that this is not the case for the multiuser interference channel mentioned above. For useful error rates, we find that soft-decision CC's to be uniformly better than RS codes when used with DS-COMA modulation in multiuser space-time channels. In our development, we use the Gaussian approximation on the interference to determine performance error bounds for systems with low number of users. Then, we check their accuracy in error rate estimation via system's simulation. These performance bounds will in turn allow us to consider a large number of users where we can estimate the gain in user-capacity due to channel coding. Lastly, the use of turbo codes is considered where it is shown that they offer a coding gain of 2.5 dB relative to soft-decision CC.
Boundary layers for the 3D primitive equations in a cube: The supercritical modes
Hamouda, M.,Jung, C.Y.,Temam, R. Pergamon Press 2016 Nonlinear analysis Vol.132 No.-
<P>In this article we study the boundary layers for the viscous Linearized Primitive Equations (LPEs) when the viscosity is small. The LPEs are considered here in a cube. Besides the usual boundary layers that we analyze here too, corner layers due to the interaction between the different boundary layers are also studied. (C) 2015 Elsevier Ltd. All rights reserved.</P>
Mousa, Hamouda M.,Tiwari, Arjun Prasad,Kim, Jinwoo,Adhikari, Surya Prasad,Park, Chan Hee,Kim, Cheol Sang Elsevier 2016 Materials letters Vol.164 No.-
<P><B>Abstract</B></P> <P>Third-generation biomaterials aim to stimulate specific cellular responses at the molecular level, these materials characterized with a resorbable and bioactivity that help body heal once they have been implanted. Here, a biomimetic method was used to generate hydroxyapatite (HA) nanoplates on the surface of AZ31B Mg alloy via anodization in simulated body fluid (SBF), followed by a hydrothermal (HT) process. The resulting nanoplates were characterized using FE-SEM, XRD, and FT-IR, surface hydrophobicity, in addition, corrosion was assessed electrochemically. The excellent bioactivity of the treated samples compared with naked ones were confirmed <I>in vitro</I> with MC3T3-E1 osteoblastic cells with significant growth and proliferation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Anodization/HT process was performed on the AZ31B Mg alloy. </LI> <LI> HA nanoplates like shape structure was generated after HT process. </LI> <LI> An improved bioactivity and corrosion resistance of the alloy was resulted. </LI> <LI> The generated nanoplates was found to mimic that in natural bone. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Intuitionistic fuzzy topological spaces: Categorical concepts
Essam Hamouda 원광대학교 기초자연과학연구소 2017 ANNALS OF FUZZY MATHEMATICS AND INFORMATICS Vol.13 No.2
Coker has introduced the concept of intuitionistic fuzzy topological spaces $(X,T)$ where $X$ is an ordinary set and $T$ is a family of intuitionistic fuzzy sets in $X$ satisfying some axioms. In this paper I introduce the fuzzy version of some universal constructions, namely, fuzzy products, fuzzy equalizers and fuzzy pullbacks for intuitionistic fuzzy topological spaces. Some results concerning all such universal objects are discussed. Finally, functors preserving equalizers and pullbacks are investigated.