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Immune Based Design of a Load Frequency Controller in Power Systems
R. BELKACEMI,A. FELLIACHI
Journal of Electrical Systems , 2008,
Abstract: An output feedback load frequency controller for a two-area power system is designed in this paper using an approach based on mimicking the human immune system.
Placental-mediated increased cytokine response to lipopolysaccharides: a potential mechanism for enhanced inflammation susceptibility of the preterm fetus
Boles JL, Ross MG, Beloosesky R, Desai M, Belkacemi L
Journal of Inflammation Research , 2012, DOI: http://dx.doi.org/10.2147/JIR.S32108
Abstract: cental-mediated increased cytokine response to lipopolysaccharides: a potential mechanism for enhanced inflammation susceptibility of the preterm fetus Original Research (1603) Total Article Views Authors: Boles JL, Ross MG, Beloosesky R, Desai M, Belkacemi L Published Date July 2012 Volume 2012:5 Pages 67 - 75 DOI: http://dx.doi.org/10.2147/JIR.S32108 Received: 22 March 2012 Accepted: 02 May 2012 Published: 30 July 2012 Julie L Boles,1 Michael G Ross,1 Ron Beloosesky,2 Mina Desai,1 Louiza Belkacemi1 1Department of Obstetrics and Gynecology, Harbor-UCLA Medical Center, Los Angeles Biomedical Research Institute at Harbor-UCLA, David Geffen School of Medicine at UCLA, University of California, Los Angeles, Torrance, CA, USA; 2Department of Obstetrics and Gynecology, Rambam Medical Center, Haifa, Israel Background: Cerebral palsy is a nonprogressive motor impairment syndrome that has no effective cure. The etiology of most cases of cerebral palsy remains unknown; however, recent epidemiologic data have demonstrated an association between fetal neurologic injury and infection/inflammation. Maternal infection/inflammation may be associated with the induction of placental cytokines that could result in increased fetal proinflammatory cytokine exposure, and development of neonatal neurologic injury. Therefore, we sought to explore the mechanism by which maternal infection may produce a placental inflammatory response. We specifically examined rat placental cytokine production and activation of the Toll-like receptor 4 (TLR4) pathway in response to lipopolysaccharide exposure at preterm and near-term gestational ages. Methods: Preterm (e16) or near-term (e20) placental explants from pregnant rats were treated with 0, 1, or 10 μg/mL lipopolysaccharide. Explant integrity was assessed by lactate dehydrogenase assay. Interleukin-6 and tumor necrosis alpha levels were determined using enzyme-linked immunosorbent assay kits. TLR4 and phosphorylated nuclear factor kappa light chain enhancer of activated B cells (NFκB) protein expression levels were determined by Western blot analysis. Results: At both e16 and e20, lactate dehydrogenase levels were unchanged by treatment with lipopolysaccharide. After exposure to lipopolysaccharide, the release of interleukin-6 and tumor necrosis alpha from e16 placental explants increased by 4-fold and 8–9-fold, respectively (P < 0.05 versus vehicle). Conversely, interleukin-6 release from e20 explants was not significantly different compared with vehicle, and tumor necrosis alpha release was only 2-fold higher (P < 0.05 versus vehicle) following exposure to lipopolysaccharide. Phosphorylated NFκB protein expression was significantly increased in the nuclear fraction from placental explants exposed to lipopolysaccharide at both e16 and e20, although TLR4 protein expression was unaffected. Conclusion: Lipopolysaccharide induces higher interleukin-6 and tumor necrosis alpha expression at e16 versus e20, suggesting that preterm pl
Fast Iterative Subspace Algorithms for Airborne STAP Radar
Belkacemi Hocine,Marcos Sylvie
EURASIP Journal on Advances in Signal Processing , 2006,
Abstract: Space-time adaptive processing (STAP) is a crucial technique for the new generation airborne radar for Doppler spread compensation caused by the platform motion. We here propose to apply range cell snapshots-based recursive algorithms in order to reduce the computational complexity of the conventional STAP algorithms and to deal with a possible nonhomogeneity of the data samples. Subspace tracking algorithms as PAST, PASTd, OPAST, and more recently the fast approximate power iteration (FAPI) algorithm, which are time-based recursive algorithms initially introduced in spectral analysis, array processing, are good candidates. In this paper, we more precisely investigate the performance of FAPI for interference suppression in STAP radar. Extensive simulations demonstrate the outperformance of FAPI algorithm over other subspace trackers of similar computational complexity. We demonstrate also its effectiveness using measured data from the multichannel radar measurements (MCARM) program.
Efficient 3D-TLM Modeling and Simulation for the Thermal Management of Microwave AlGaN/GaN HEMT Used in High Power Amplifiers SSPA
Karim Belkacemi,Rachida Hocine
- , 2018, DOI: https://doi.org/10.3390/jlpea8030023
Abstract: Abstract A three-dimensional thermal simulation investigation for the thermal management of GaN-on-SiC monolithic microwave integrated circuits (MMICs) of consisting multi-fingers (HEMTs) is presented. The purpose of this work is to demonstrate the utility and efficiency of the three-dimensional Transmission Line Matrix method (3D-TLM) in a thermal analysis of high power AlGaN/GaN heterostructures single gate and multi-fingers HEMT SSPA (solid state power amplifiers). The self-heating effects induce thermal cross-talk between individual fingers in multi-finger AlGaN/GaN that affect device performance and reliability. Gate-finger temperature differences only arise after a transient state, due to the beginning of thermal crosstalk which is attributed to the finite rate of heat diffusion between gate fingers. The TLM method accounts for the real geometrical structure and the non-linear thermal conductivities of GaN and SiC in order to improve the realistic calculations accuracy heat dissipation and thermal behavior of the device. In addition, two types of heat sources located on the top of GaN layer are considered in thermal simulations: Nano-scale hotspot as a pulsed wave heat source under gate and micro-scale hotspot as a continuous wave heat source, between gate and drain. Heat diffusion however, occurs not only between individual gate fingers (inter-finger) in a multi-finger HEMT, but also within each gate finger (intra-finger). To compare results, a Micro-Raman Spectroscopy experience is conducted to obtain a detailed and accurate temperature distribution. Good agreement between the microscopic spectral measurement and TLM simulation results is observed by accepting an error less than 2.2% relative to a maximum temperature. Results show that the 3D-TLM method is suitable for understanding heat management in particular for microwave devices AlGaN/GaN HEMTs SSPA amplifier. TLM method helps to select and locates the expected hot spots and to highlight the need of thermal study pre-design in order to minimize the system-level thermal dissipation and lead therefore to higher reliability. View Full-Tex
A Genetic Algorithm for Solving the Optimal Power Flow Problem
Tarek BOUKTIR,Linda SLIMANI,M. BELKACEMI
Leonardo Journal of Sciences , 2004,
Abstract: This paper presents solution of optimal power flow problem of large distribution systems via a simple genetic algorithm. The objective is to minimize the fuel cost and keep the power outputs of generators, bus voltages, shunt capacitors/reactors and transformers tap-setting in their secure limits. CPU times can be reduced by decomposing the optimization constraints to active constraints manipulated directly by the genetic algorithm, and passive constraints maintained in their soft limits using a conventional constraint load flow. The IEEE 30-bus system has been studied to show the effectiveness of the algorithm.
High-Resolution Source Localization Algorithm Based on the Conjugate Gradient
Hichem Semira,Hocine Belkacemi,Sylvie Marcos
EURASIP Journal on Advances in Signal Processing , 2007, DOI: 10.1155/2007/73871
Abstract: This paper proposes a new algorithm for the direction of arrival (DOA) estimation of P radiating sources. Unlike the classical subspace-based methods, it does not resort to the eigendecomposition of the covariance matrix of the received data. Indeed, the proposed algorithm involves the building of the signal subspace from the residual vectors of the conjugate gradient (CG) method. This approach is based on the same recently developed procedure which uses a noneigenvector basis derived from the auxiliary vectors (AV). The AV basis calculation algorithm is replaced by the residual vectors of the CG algorithm. Then, successive orthogonal gradient vectors are derived to form a basis of the signal subspace. A comprehensive performance comparison of the proposed algorithm with the well-known MUSIC and ESPRIT algorithms and the auxiliary vectors (AV)-based algorithm was conducted. It shows clearly the high performance of the proposed CG-based method in terms of the resolution capability of closely spaced uncorrelated and correlated sources with a small number of snapshots and at low signal-to-noise ratio (SNR).
High-Resolution Source Localization Algorithm Based on the Conjugate Gradient
Semira Hichem,Belkacemi Hocine,Marcos Sylvie
EURASIP Journal on Advances in Signal Processing , 2007,
Abstract: This paper proposes a new algorithm for the direction of arrival (DOA) estimation of P radiating sources. Unlike the classical subspace-based methods, it does not resort to the eigendecomposition of the covariance matrix of the received data. Indeed, the proposed algorithm involves the building of the signal subspace from the residual vectors of the conjugate gradient (CG) method. This approach is based on the same recently developed procedure which uses a noneigenvector basis derived from the auxiliary vectors (AV). The AV basis calculation algorithm is replaced by the residual vectors of the CG algorithm. Then, successive orthogonal gradient vectors are derived to form a basis of the signal subspace. A comprehensive performance comparison of the proposed algorithm with the well-known MUSIC and ESPRIT algorithms and the auxiliary vectors (AV)-based algorithm was conducted. It shows clearly the high performance of the proposed CG-based method in terms of the resolution capability of closely spaced uncorrelated and correlated sources with a small number of snapshots and at low signal-to-noise ratio (SNR).
Synthesis of Gold Catalysts Supported on Mesoporous Silica Materials: Recent Developments
Luis-Felipe Gutiérrez,Safia Hamoudi,Khaled Belkacemi
Catalysts , 2011, DOI: 10.3390/catal1010097
Abstract: Mesoporous silica materials (MSM) with ordered and controllable porous structure, high surface area, pore volume and thermal stability are very suitable catalyst supports, because they provide high dispersion of metal nanoparticles and facilitate the access of the substrates to the active sites. Since the conventional wet-impregnation and deposition-precipitation methods are not appropriate for the incorporation of gold nanoparticles (AuNPs) into MSM, considerable efforts have been made to develop suitable methods to synthesize Au/MSM catalysts, because the incorporation of AuNPs into the channel system can prevent their agglomeration and leaching. In this review, we summarize the main methods to synthesize active gold catalysts supported on MSM. Examples and details of the preparative methods, as well as selected applications are provided. We expect this article to be interesting to researchers due to the wide variety of chemical reactions that can be catalyzed by gold supported catalysts.
New Control Approach for Permanent Magnet Synchronous Motor
A. Loukdache,J. Alami,M. El Belkacemi,A. El Imrani
International Journal of Electrical and Power Engineering , 2012,
Abstract: Permanent magnet synchronous motors are often used in electrical drives because of their simple structures, ease of maintenance and high efficiency. However, these motors have a nonlinear characteristic arisen from motor dynamics and load characteristics. To overcome this problem, a new speed controller based on genetic algorithms for the drive system is proposed in this study. To illustrate the performance of the proposed controller, a conventional proportional integral controller is used as well to the speed control of permanent magnet synchronous motors. Simulations are realized by both control strategies and simulation results are presented and compared with the conventional control.
Drug-eluting Balloons in Coronary Artery Disease: Past, Present and Future
Anouar Belkacemi,Pieter Stella,Michiel Voskuil,Kevin Onsea
European Journal of Cardiovascular Medicine , 2012,
Abstract: Percutaneous treatment of complex coronary lesions like small vessel disease, diabetics and long diffuse disease, remain hampered by suboptimal results, even with the use of drug-eluting stents (DES). The paclitaxel drug-eluting balloon (DEB) is an interesting emerging device to optimise the clinical outcomes in these specific lesions. In order to inhibit coronary restenosis, and revascular- isation, the DEB may become a viable alternative treatment option by means of a high concentration,local release of an anti-restenotic drug, paclitaxel, into the coronary vessel without using a metalscaffold or durable polymers.Several studies have already shown promising and consistent results in the treatment of in-stent restenosis. Even when compared to certain DES, the DEB has demonstrated its added value. Inspired by these results, an increasing number of studies have been started in different coronary lesion subsets, exploring the value of the DEB in a broader range of lesions.It will be interesting to see whether the DEB will find more indications beyond in-stent resteno- sis treatment. Moreover, as several DEB produced by different manufacturers, are present on the market, specific investigations are needed to address whether these devices offer the same added value, or show relevant differences.As accounted for DES development in the past, now the puzzle pieces have to be put together for DEB.
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