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Characterization of Tunisian marine sediments in Rades and Gabes harbors

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International Journal of Sediment Research 2014年第3期29卷 391-401页

作者： Imen BEL HADJ ALI Zoubeir LAFHAJ Mounir BOUASSIDA Imen SAID ecole Centrale de Lille Villeneuve d'AscqFrance and Ecole Nationale d'Ingenieurs de TunisTunisia ecole centrale de Lille Villeneuve d'AscqFrance Universite de Tunis El Manar/ecole nationale d'Ingenieurs de Tunis/05-UR-11 06 Universite de Tunis El Manar/ecole nationale d'Ingenieurs de Tunis/05-UR-1106

The objective of this article is to study the geotechnical and environmental characteristics of sediments dredged from two Tunisian harbors:Rades and *** first harbor represents the main facility place in the national transport *** second one is selected as its sediments present a serious ecological constraint caused by the discharge of wastes into the marine *** sediments are either discarded at sea or landfilled despite their harmful effects on the *** article is divided into three main *** first one presents the material that was carried for Rades and Gabes *** conservation conditions and the used experimental tests are *** characterization includes the determination of the grain size distribution,the water content,the Atterberg limits,the methylene blue value,the specific area,the bulk density,the specific unit weight,the organic and carbonate *** characterization is assessed by the determination of metals concentrations in a leaching *** second section deals with the description and analysis of geotechnical properties of Rades and Gabes harbors’ *** results obtained show that Rades harbor sediments are slightly sandy clayey silts whereas Gabes harbor sediments are silty sands characterized by a highly plastic clay *** of the two sediments don’t exhibit a high organic ***,chemical,mineralogical and environmental properties are presented and then *** experimental results obtained show that Rades and Gabes sediments could be used as a sand substitute in the formulation of a new construction *** harbor sediments are more polluted than Rades harbor sediments.

关键词： Sediments Characterization Geotechnical Environmental Valorization

Effect of Titania Additive on Structural and Mechanical Properties of Alumina–Fluorapatite Composites

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Journal of Materials Science & Technology 2012年第12期28卷 1130-1136页

作者： Awatef Guidara Kamel Chaari Jamel Bouaziz Laboratoire de chimie industrielle Ecole Nationale d'Ingnieurs de SfaxBP 1173 3038 Tunisie

Mechanical properties of alumina-fluorapatite composites with different titania additive amounts （0, 0.5, 1, 1.4, 2, 3, 4 and 5 wt%） have been investigated between 1200 and 1600℃. The optimum values of densification and mechanical properties of composites have been reached with 1.4 wt% of titania after the sintering process at 1500℃ for 1 h. Thus, the rupture strength of alumina-26.52 wt% Fap-1.4 wt% TiO2 reaches 75 MPa. At higher temperature and beyond 1.4 wt% TiO2 ,the densification and mechanical properties were hindered by the formation of both intergranular porosity and secondary phase. X-ray diffraction （XRD） analysis of alumina-Fap-TiO2 composites shows the formation of aluminium titanate （Al2O3-TiO2：Al2TiO5 ）. The 27Al magic angle scanning nuclear magnetic resonance analysis of Al2O3-Fap-TiO2 composites reveals the presence of octahedral and pentahedral aluminium and novel environment relative to tetrahedral aluminium sites.

关键词： Sintering Fluorapatite Alumina Titania Composites Biomedical applications

A comparative study of adsorption and regeneration with different agricultural wastes as adsorbents for the removal of methylene blue from aqueous solution

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Chinese Journal of Chemical Engineering 2017年第9期25卷 1282-1287页

作者： Sana Dardouri Jalila Sghaier Unité de Thermique et Thermodynamique des Procédés Industriels Ecole Nationale d'Ingénieurs de Monastir

Removal of dye from the industrial wastewater is one of the most important subjects in water pollution *** adsorption/desorption cycles of a basic dye, methylene blue, on the internal almond shell, sheep manure waste and sawdust were investigated using fixed bed column experiments in order to study the adsorption capacity to remove MB and adsorbent regeneration efficiency. The adsorption breakthrough curves were predicted by the Thomas model, Yoon Nelson model, and Wolborska model and modified dose–response model using non-linear regression analysis. The results showed that the modified dose–response model was more suitable for the description of breakthrough curves for three adsorbents only in the first cycle. Although sheep manure waste presents the highest adsorption capacity, it is hard to regenerate and needs more time regeneration. Conversely, the internal almond shell presents lower adsorption capacity, but they are more readily regenerated.

关键词： Fixed bed adsorption Breakthrough curves modeling Adsorbents selection Methylene blue Regeneration

Integration of automatic voltage regulator and power system stabilizer: small-signal stability in DFIG-based wind farms

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Journal of Modern Power Systems and Clean Energy 2019年第5期7卷 1115-1128页

作者： Sirine ESSALLAH Adel BOUALLEGUE Adel KHEDHER Universite de Sousse Ecole Nationale d’Ingenieurs de SousseLATIS-Laboratory of Advanced Technology and Intelligent Systems4023 SousseTunisia

The increasing penetration of wind farms in the energy sector directly affects the dynamic behavior of the power *** increasing use of wind energy in the power system worsens its stability and inherently influences the firmness of a small *** investigate these effects,one of the synchronous generators(SGs)of the grid is considered defective and is replaced by a doubly fed induction generator(DFIG)-based wind farm of the same *** small-signal stability of a power system is usually evaluated via eigenvalue analysis where local-area and inter-area oscillatory modes for the New England test system are *** controls,such as automatic voltage regulator(AVR)and power system stabilizer(PSS),are added to attenuate the generated *** this study,the impact of wind energy on the small-signal stability of the power system is *** combinations of AVR and PSS types are considered to mitigate the undesirable alterations.A comparative study is performed based on numerical simulations to choose the best combination of AVR and PSS *** obtained results prove that the proposed combination yields good results in terms of stability enhancement both under normal operating conditions and in DFIG-based wind farms.

关键词： Power system stability Power transmission system Transient analysis Voltage regulation

Regional gradient observability for semilinear hyperbolic systems： HUM approach

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Control Theory and Technology 2018年第1期16卷 72-80页

作者： Adil KHAZARI Ali BOUTOULOUT Imad EL HARRAKI Sidi Mohamed Ben Abdellah University Ecole Nationale de Commerce et de gestion Fez Morocco TSI Team MACS Laboratory Faculty of Sciences Moulay Ismail University Meknes Morocco ecole nationale superieure des mines de Rabat Rabat Morocco

The paper aims to extend the notion of regional observability of the gradient to the semilinear hyperbolic case, in order to reconstruct the gradient of the initial conditions in a subregion w of the domain evolution Ω. We start with an asymptotically linear system, the approach is based on an extension of the Hilbert uniqueness method （HUM） and Schauder＇s fixed point theorem. The analysis leads to an algorithm which is successfully numerically implemented and illustrated with examples and simulations.

关键词： Distributed systems fixed point regional gradient observability regional reconstruction semilinear hyperbolic systems

Mechanical Characterisation of Interface for Steel/Polymer Composite Using Pull-out Test: Shear-Lag and Frictional Analysis

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Journal of Materials Science & Technology 2006年第4期22卷 552-558页

作者： Mohamed KHARRAT Maher DAMMAK Amine CHARFI Institut Préparatoire aux Etudes d'Ingénieurs de Sfax Tunisia Laboratoire des Systèmes ElectromécaniquesEcole Nationale d'Ingénieurs de SfaxTunisia Laboratoire des Systèmes Electromécaniques Ecole Nationale d'Ingénieurs de SfaxTunisia

Fibre-matrix interface is known to have contribution to the mechanical performance of fibre-reinforced composite by its potential for load transfer between the fibre and the matrix. Such load transfer is of great importance in dentistry when a post is used for fixing a ceramic crown on the tooth. In this study, a pull-out test was carried out to analyse the interfacial properties of a steel fibre embedded in a polyester and epoxy matrices. It was found that the fibre-matrix interface is debonded on the whole embedded length when the fibre stress reached the debonding stress. Then, the fibre stress fell down to the initial extraction stress required to pulling out the debonded fibre from the matrix. Both debonding stress and initial extraction stress initiated a linear increase with the implantation length after the debonding stress reached horizontal asymptotes. To analyse the fibre-matrix load transfer before debonding, an analytical shear-lag model was adopted to in this test conditions. Fitting the experimental results with the analytical model provided the interfacial shear strength. By considering the Coulomb friction at the fibre-matrix interface during the fibre extraction process, an analytical model which considers Poisson＇s effects on both fibre and matrix, was developed. In this model, knowledge of the initial extraction stress of the fibre provides the residual normal stress at the fibre-matrix interface.

关键词： Fibre Matrix Interface Pull-out Shear-lag debonding Friction

Tribological Investigation of HDPE-cuttlebone and HDPE-red Coral Composites

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Journal of Bionic Engineering 2019年第6期16卷 1068-1079页

作者： Amira Salem Walid Bensalah Salah Mezlini Universite de Monastir Ecole Nationale d'Ingenieurs de Monastir(ENIM)Laboratoire de Genie Mecanique(LGM)LR99ES325019MonastirTunisia

In this paper,the tribological properties of cuttlebone(CB)-reinforced high density polyethylene(HDPE)and Red Coral(RC)-reinfbrced HDPE composites were *** composite specimens were prepared with a hot compression molding machine using different weight proportions of fillers blended with *** tribological behavior of the composite disks was studied using pin-on-disk tribometer under dry condition against stainless steel M30NW *** coefficient of friction as well as wear rate were examined to study the effects of the two fillers on the tribological perfonnance of both *** wear tests,different composites were examined using a Scanning Electron Microscope(SEM).It was fbund that the use of cuttlebone(CB)and Red Coral(RC)as reinforcement improved the tribological properties of HDPE.

关键词： cuttlebone-reinforced HDPE red coral-reinforced HDPE wear rate friction coefficient wear mechanism

Improving contrast and sectioning power in confocal imaging by third harmonic generation in SiOx nanocrystallites

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Chinese Optics Letters 2007年第8期5卷 477-479页

作者： Gilbert Boyer Karsten Plamann Laboratoire d'Optique Appliqude Ecole Polytechnique-Ecole Nationale Supérieure de Techniques A vancdes-CNRS UMR 7639 Centre de l'Yvette chemin de la Hunière 91761 Palaiseau cedex France

We present a new optical microscope in which the light transmitted by a sample-scanned transmission confocal microscope is frequency-tripled by SiOx nanocrystallites in lieu of being transmitted by a confocal pinhole. This imaging technique offers an increased contrast and a high scattered light rejection. It is demonstrated that the contrast close to the Sparrow resolution limit is enhanced and the sectioning power are increased with respect to the linear confocal detection mode. An experimental implementation is presented and compared with the conventional linear confocal mode.

关键词： mode Improving contrast and sectioning power in confocal imaging by third harmonic generation in SiO_x nanocrystallites THG

Active Queue Management Exploiting the Rate Information in TCP-IP Networks

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IEEE/CAA Journal of Automatica Sinica 2018年第1期5卷 223-231页

作者： Abderrahmane Boudi Malik Loudini Laboratoire de la Communication dans les Systemes Informatiques Ecole nationale Superieure d'Informatique ESI Algiers 16309 Algeria IEEE

In this paper, we propose a new mechanism called explicit rate notification(ERN) to be used in end-to-end communications. The ERN scheme encodes in the header of transmission control protocol(TCP) packets information about the sending rate and the round trip time(RTT) of the flows. This new available information to the intermediate nodes(routers) is used to improve fairness, increase utilization, decrease the number of drops, and minimize queueing delays. Thus, it induces a better management of the queue. A comparison of our scheme with preexistent schemes, like the explicit congestion notification scheme, shows the effectiveness of the proposed mechanism.

关键词： Active queue management congestion control fairness transmission control protocol(TCP)