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Search Results: 1 - 10 of 461922 matches for " A. Chaker "
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Neural Adaptive Control by State Space Regulator of Universal Charge for the Compensation of Active and Reactive Power
A. Bouanane,A. Chaker
International Journal of Electrical and Power Engineering , 2012, DOI: 10.3923/ijepe.2012.43.50
Abstract: In the present study, researchers present the effectiveness of the controller trical power flow universal (Unified Power Flow Controller, UPFC) with the choice of a control strategy. To evaluate the performance and robustness of the system, we proposed a hybrid control combining the concept of neural networks with conventional regulators vis-a-vis the changes in characteristics of the transmission line in order to improve the stability of the electrical power network.
Optimal Distribution of the Reactive Power and Voltages Control in Algerian Network Using the Genetic Algorithm Method
S. Chettih,M. Khiat,A. Chaker
Information Technology Journal , 2008,
Abstract: This study presents a Genetic Algorithm (GA) approach for solving the reactive power flow problem including the line flow constraint. Minimizations of real power loss with FACTS and without FACTS devices are the objectives of this reactive power optimization problem. The proposed method has been successfully applied in the case of the western Algerian transmission system. The FACTS placement problem considers the upper and lower bound constraints of the voltage at different load levels by minimizing the system loss. The simulation results are promising and show the effectiveness and robustness of the proposed approach.
Voltage Control and Reactive Power Optimisation using the Meta Heuristics Method: Application in the Western Algerian Transmission System
S. Chettih,M. Khiat,A. Chaker
Journal of Artificial Intelligence , 2011,
Abstract: This study reported on a meta heuristics method for solving the optimal reactive power flow problem we proposed an application of particle Swarm Optimization Method (PSO), compared to the GA method. The methods incorporate natural ideas to give load flow solution. To demonstrate the global reactive power optimisation of those methods it is applied to the Western Algerian Transmission System 68 bus 220/60 kV. To show the contribution of new techniques, the simulation results are compared with work history using a hybrid approach.
Thermal-Hydraulic Simulation of a Radiant Steam Boiler Tube Rupture Transient Using Relap5/Mod3.2
A.L. Deghal Cheridi,A. Chaker,A. Loubar
Journal of Engineering and Applied Sciences , 2012, DOI: 10.3923/jeasci.2012.100.107
Abstract: A steam boiler is a complex system comprised of numerous components. In the operation of industrial steam boiler, it is very important to evaluate different accident scenarios in actual plant conditions. One of the main accidents is steam generator tube rupture. Numerical simulation using best estimate computer codes like Relap5 are useful for understanding thermal-hydraulic behavior of a steam boiler during normal and accidental operating conditions. In this study, the analytical investigation of an industrial steam boiler behavior during feedwater line break accident is discussed. A detailed nodalization of the steam boiler installation is developed based on Relap5/Mod3.2 to be suitable for the analysis of the various accidents. The control and regulation systems are also considered. Water level, pressure, temperature and flow rates profiles are presented in various steam boiler system components. From the result, the thermal-hydraulic code correctly predicts the behavior of the main plant parameters in comparison with the experimental data and how the control system when required can successfully mitigate the accident.
Influence de la phosphatation au zinc sur la résistance a la corrosion d’un acier au carbone en milieu maring
A Ettaqi, A Irhzo, RD Daoudi, B Chaker
Afrique Science: Revue Internationale des Sciences et Technologie , 2005,
Abstract: Zinc phosphatation influence on the resistance to corrosion of a carbonbased steel in marine medium In the frame of the present investigation, we have showed that the profile of the cathodic curves of a non phosphated metal, plead in favour to a kinetic profile essentially monitored by a pure diffusion. The corrosion rate, obtained from the cathodic curves as well as by a colorimetrical dosage of the dissolved iron, increases when the rotation speed of the electrode increases. Which show a diffusional control the phosphatation of the electrode does not seem to modify the cathodic curves profile. However the height of the diffusion palier depends on the thickness of the phosphatation layer. It takes values lower than those of an uncovered steel for a layer thickness of two micrometers the phosphatation layer reinforce notably the resistance to the corrosion of the internal layer which is essentially composed with iron oxides, by decreasing the corrosion rate with the increase of the layer. However, the benefical effect of the phosphatation is maximal for a thickness of three micrometers. This effect occurs also during the anodic behaviour.
Anatomical, Clinical and Electrical Observations in Piriformis Syndrome
Roger M Jawish, Hani A Assoum, Chaker F Khamis
Journal of Orthopaedic Surgery and Research , 2010, DOI: 10.1186/1749-799x-5-3
Abstract: Between 3550 patients complaining of sciatica, we concluded 26 cases of piriformis syndrome, 15 females, 11 males, mean age 35.37 year-old. We operated 9 patients, 2 to 19 years after the onset of symptoms, 5 had piriformis steroids injection. A dorsolumbar MRI were performed in all cases and a pelvic MRI in 7 patients. The electro-diagnostic test was performed in 13 cases, between them the H reflex of the peroneal nerve was tested 7 times.After a followup 1 to 11 years, for the 17 non operated patients, 3 patients responded to conservative treatment. 6 of the operated had an excellent result, 2 residual minor pain and one failed. 3 new anatomical observations were described with atypical compression of the sciatic nerve by the piriformis muscle.While the H reflex test of the tibial nerve did not give common satisfaction in the literature for diagnosis, the H reflex of the peroneal nerve should be given more importance, because it demonstrated in our study more specific sign, with six clinical criteria it contributed to improve the method of diagnosis. The cause of this particular syndrome does not only depend on the relation sciatic nerve-piriformis muscle, but the environmental conditions should be considered with the series of the anatomical anomalies to explain the real cause of this pain.Since many years, we had a particular interest for the intractable sciatica with failure of long term treatment of lumbar pain. In such cases, our investigation was focused on a suspected piriformis syndrome missing from many decades specific signs for diagnosis.Yeoman [1] 1928, reported that the sciatica may be caused by a periarthritis involving the anterior sacroiliac ligament, the piriformis muscle and the adjacent branches of the sciatic nerve. Freiberg and Vinke [2] 1934, considered that the inflammation of the sacroiliac joint may primarily cause reaction of the piriformis muscle and its fascia, and secondarly, the irritation of the overlying lumbosacral plexus.Based on
Chemical Composition and Antimicrobial Activity of Essential oil of Genista numidica Spach. and G. saharae Coss et Dur
T. Lograda,A.N. Chaker,P. Chalard,M. Ramdani
Asian Journal of Plant Sciences , 2009,
Abstract: The hydrodistilled oils from the aerial parts of Genista numidica and G. saharae, which are endemic to Algeria, were analyzed by Gas Chromatography-Mass Spectrometry (GC-MS). Sixty nine compounds in the oil of G. numidica representing 87% of the total oil and 58 compounds of G. saharae, representing 91% of the total oil were identified. The analysis showed that the main constituents of the essential oils are rich in fatty acid. The major constituent are lauric acid (9.1-8.4%), myristic acid (13.5-14.5%), palmitic acid (15.3-32.3%) and linoleic acid (0-2.4%). The effects of these oils on the growth of Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853) and Staphylococcus aureus (ATCC 25923) were investigated by the diffusion method. The oils showed no significant antibacterial activities.
Artificial Neural Networks Approach to the Modelling of AC Arcs Maintenance Conditions on Ice-covered Insulators
B. Zegnini,D. Mahi,J. Martinez-Vega,A. Chaker
Journal of Applied Sciences , 2006,
Abstract: This study is about a kind of ANN for applications in multivariate nonlinear regression, in order to further knowledge and understanding of discharge on an iced insulator surface and the development into a flashover AC arcs. The propagation of local arcs is necessary for a flashover to occur on an ice-covered insulator. It was supposed that the local AC arc extended when it satisfied the arc re-ignition conditions. Therefore, the minimum applied voltage for maintaining an arc burning steadily across an air gap under various conditions is a major parameter and it is referred as arc maintenance. Although ANNs have usually achieved good performances in several domains, those performances and the ANN training process are directly influenced by an appropriate choice of the network architecture. In this study an attempt has been made to model Va = f (I, L, x) for estimating the arc re-ignition conditions as estimator function of leakage current, air gap length and insulator length using multi-layer feed-forward neural network with back propagation technique and the Radial Basis Function (RBF) neural network with Orthogonal Least-Squares (OLS) learning method. A number of test results taken from the CIGELE models were simulated and analyzed and a comparison between RBF network and BP network is presented. The RBF ANNs model was found to be reliable in predicting the arc maintenance voltage, under any given set of leakage current, insulator length and air gap length. A satisfactory agreement will be observed between the simulated and experimental results.
H Robust Control for a Plasma CF4/O2 System
K. Chaker
International Journal of Soft Computing , 2012,
Abstract: This study describes a multivariable H robust control approach, for an ill conditioned, difficult to control system, given by a plasma chemical reactor CF4/O2. The control of such a system resulted, in the past, in a slow, oscillatory coupled response. The goals of applying H robust control, is the achievement of a decent smooth response with minimum oscillations and overshoot. In the pursuit of this goal, we proceed to the quantification of uncertainties affecting the plasma process. Then, the robustness conditions in closed loop, to be achieved, are clearly stated. Only then, the H algorithm is applied, after the construction of the augmented system resulting from the standard process form. The results obtained showed, clearly, the advantages of the H robust control approach, within the robustness a-priori set conditions.
Altered Responses to Cold Environment in Urocortin 1 and Corticotropin-Releasing Factor Deficient Mice
Bayan Chaker,Tareq A. Samra,Nabanita S. Datta,Abdul B. Abou-Samra
Physiology Journal , 2013, DOI: 10.1155/2013/185767
Abstract: We examined core body temperature (CBT) of urocortin 1 (UCN1) and corticotropin releasing factor (CRF) knockout (KO) mice exposed to 4°C for 2？h. UCN1KO mice showed higher average CBT during cold exposure as compared to WT. The CBT of male and female WT mice dropped significantly to and ？C at 4°C, respectively. In contrast, the CBT of male and female UCN1KO mice dropped only slightly after 2？h at 4°C to and ？C, respectively. WT female and male UCN1KO mice showed significant acclimatization to cold; however, female UCN1KO mice did not show such a significant acclimatization. CRFKO mice showed a dramatic decline in CBT from at 22°C to at 4°C for 2？h. The CRF/UCN1 double KO (dKO) mice dropped their CBT to after 2？h exposure to 4°C. Dexamethasone treatment prevented the decline in CBT of the CRFKO and the dKO mice. Taken together, the data suggest a novel role for UCN1 in thermoregulation. The role of CRF is likely secondary to adrenal glucocorticoids, which have an important regulatory role on carbohydrate, fat, and protein metabolism. 1. Introduction Corticotropin releasing factor (CRF) [1] plays an essential role in the physiological regulation of the hypothalamic-pituitary-adrenal (HPA) as CRF knockout (KO) mice have low concentrations of corticosterone and decreased response to stress [2]. CRF is also found in several regions of the central nervous system (CNS) where it functions as a neurotransmitter and regulates several aspects of behavior particularly in response to stressful stimuli [3]. The urocortins, UCN1 [4], UCN2 [5], and UCN3 [6], are a family of peptides, which were discovered by their sequence homology to CRF, sauvagine [7], and urotensin 1 [8]. These peptides bind and activate the CRF receptors, CRFR1 [9] and CRFR2 [10], with different affinities and potencies. CRF binds to CRFR1 with a higher affinity than to CRFR2, whereas UCN1, sauvagine, and urotensin 1 interact with both receptors with a relatively similar affinity [10]. In contrast, UCN2 and UCN3 have higher affinity for CRFR2 than for CRFR1 [5, 6]. Therefore, the actions of UCN1 can be mediated by both CRF receptors [11]. In this regard, it has been shown that UCN1 mRNA levels are upregulated in the Edinger-Westphal (EW) nucleus of mice following stress exposure [12]. UCN1-deficient mice were shown to have a normal corticosterone response to acute immobilization stress [13, 14]; however, they showed anxiety-like behavior and impaired inner ear physiology [13]. UCN1KO mice were also shown to have decreased corticosterone response to cold and impaired adaptation to repeated
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