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Polyester-supported Chitosan-Poly(vinylidene fluoride)-Inorganic-Oxide-Nanoparticles Composites with Improved Flame Retardancy and Thermal Stability

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Chinese Journal of Polymer Science 2020年第1期38卷 84-91,I0007页

作者： Ahmed Abed Nabil Bouazizi Stephane Giraud Ahmida El Achari Christine Campagne Olivier Thoumire Reddad El Moznine Omar Cherkaoui Julien Vieillard abdelkrim azzouz ENSAIT GEMTEX-Laboratoire de Genie et Materiaux TextilesF-59000 LilleFrance Laboratory LPMC Faculty of Science El JadidaChouaib Doukkali UniversityEl JadidaMorocco Laboratory REMTEX ESITHRouted'EI Jadidakm8BP 7731-OulfaCasablancaMorocco Normandie Univ. UNIROUENCNRSPBS(UMR 6270)55 rue Saint Germain27000 EvreuxFrance Normandie Univ. UNI ROUENINSA RouenCNRSCOBRA(UMR 6014)55 rue Saint Germain27000 EvreuxFrance Nanoqam Department of ChemistryUniversity of Quebec at MontrealQCCanada

Polyester(PET) was pre-activated by atmospheric air plasma and coated by various inorganic oxide nanoparticles(MOx) such as titanium dioxide(TiO2), zinc oxide(ZnO), and silicon oxide(SiO2), using poly(vinylidene fluoride)(PVDF) and chitosan(CT) as binders. The resulting PET-PVDF-MOx-CT composites were thermally compressed and then characterized by scanning electron microscopy, Fourier infrared spectroscopy, thermal gravimetric analysis, and flame retardancy(FR) ability tests. PET modifications resulted in more thermally stable and less harmful composites with weaker hazardous gas release. This was explained in terms of structure compaction that blocks pyrolysis gas *** incorporation was found to reduce the material susceptibility to oxidation. This judicious procedure also allowed improving flame retardancy ability, by lengthening the combustion delay and slowing the flame propagation. Chitosan also turned out to contribute to a possible synergy with the other polymers present in the synthesized materials. These results provide valuable data that allow understanding the FR phenomena and envisaging low-cost high FR materials from biodegradable raw materials.

关键词： Polyester nonwovens Composite PVDF Flame retardancy Material oxides Chitosan

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Enhanced Chimp Optimization Algorithm Using Attack Defense Strategy and Golden Update Mechanism for Robust COVID-19 Medical Image Segmentation

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Journal of Bionic Engineering 2024年第4期21卷 2086-2109页

作者： Amir Hamza Morad Grimes abdelkrim Boukabou Samira Dib Non Testing Destructive Laboratory Faculty of TechnologyUniversity of Jijel18000JijelAlgeria Laboratory of Renewable Energy Faculty of TechnologyUniversity of Jijel18000JijelAlgeria

Medical image segmentation is a powerful and evolving technology in medical *** fact,it has been identified as a very effective tool to support and accompany doctors in their fight against the spread of the coronavirus(COVID-19).Various techniques have been utilized for COVID-19 image segmentation,including Multilevel Thresholding(MLT)-based meta-heuristics,which are considered crucial in addressing this ***,despite their importance,meta-heuristics have significant ***,the imbalance between exploration and exploitation,as well as premature convergence,can cause the optimization process to become stuck in local optima,resulting in unsatisfactory segmentation *** this paper,an enhanced War Strategy Chimp Optimization Algorithm(WSChOA)is proposed to address MLT *** strategies are incorporated into the traditional Chimp Optimization *** update mechanism that provides diversity in the ***,the attack and defense strategies are incorporated to improve the search space leading to avoiding local *** experimental results were conducted by comparing WSChoA with recent and well-known algorithms using various evaluation metrics such as Feature Similarity Index(FSIM),Structural Similarity Index(SSIM),Peak signal-to-Noise Ratio(PSNR),Standard deviation(STD),Freidman Test(FT),and Wilcoxon Sign Rank Test(WSRT).The results obtained by WSChoA surpassed those of other optimization techniques in terms of robustness and accuracy,indicating that it is a powerful tool for image segmentation.

关键词： Image processing Segmentation Optimization Chimp Golden update mechanism Attack-defense strategy COVID-19

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Overall Assessment of Heat Transfer for a Rarefied Flow in a Microchannel with Obstacles Using Lattice Boltzmann Method

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工程与科学中的计算机建模(英文) 2024年第1期138卷 273-299页

作者： Siham Hammid Khatir Naima Omolayo M.Ikumapayi Cheikh Kezrane abdelkrim Liazid Jihad Asad Mokdad Hayawi Rahman Farhan Lafta Rashid Naseer Ali Hussien Younes Menni Laboratory of Development in Mechanics and Materials(LDMM) Zian Achour UniversityDjelfaPB 3117Algeria Department of Technology University Center Salhi Ahmed Naama(Ctr.Univ.Naama)P.O.Box 66Naama45000Algeria Department of Mechanical and Mechatronics Engineering Afe Babalola University Ado Ekiti360101Nigeria Departement of Physics Faculty of ScienceAbou Bekr Belkaid UniversityTlemcen13000Algeria Department of Physics Faculty of Applied SciencesPalestine Technical University-KadoorieTulkarmPalestine Aeronautical Technical Engineering Al-Farahidi UniversityBaghdad10011Iraq Mechanical Engineering Department University of KerbalaKarbala56001Iraq Information and Communication Technology Research Group Scientific Research CenterAl-Ayen UniversityThi-QarIraq National University of Science and Technology Dhi QarIraq

The objective of this investigation is to assess the effect of obstacles on numerical heat transfer and fluid flow momentum in a rectangular microchannel(MC).Two distinct configurations were studied:one without obstacles and the other with alternating obstacles placed on the upper and lower *** research utilized the thermal lattice Boltzmann method(LBM),which solves the energy and momentum equations of fluids with the BGK approximation,implemented in a Python coding *** jump and slip velocity conditions were utilized in the simulation for the MC and extended to all obstacle *** study aims to analyze the rarefaction effect,with Knudsen numbers(Kn)of 0.012,0.02,and *** outcomes indicate that rarefaction has a significant impact on the velocity and temperature *** presence of nine obstacles led to slower fluid movement inside the microchannel MC,resulting in faster cooling at the *** MCs with obstacles,the rarefaction effect plays a crucial role in decreasing the Nusselt number(Nu)and skin friction coefficient(Cf).Furthermore,the study demonstrated that the obstacles played a crucial role in boosting fluid flow and heat transfer in the *** findings suggest that the examined configurations could have potential applications as cooling technologies in micro-electro-mechanical systems and microdevice applications.

关键词： Microfluid rarefied flow LBM microchannel Knudsen number numerical simulation

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A 3D Numerical Study of LO_2/GH_2 Supercritical Combustion in the ONERA-Mascotte Test-rig Configuration

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Journal of Thermal Science 2016年第1期25卷 97-108页

作者： abdelkrim Benmansour abdelkrim Liazid Pierre-Olivier Logerais Jean-Félix Durastanti Laboratory LTE ENP-OranBP 1523 El Mnaouer 31000Oran Algeria Universite de Paris-Est CERTESIUT de Senartrue Georges Charpak77567 LieusaintFrance

Cryogenic propellants LOx/H2 are used at very high pressure in rocket engine combustion. The description of the combustion process in such application is very complex due essentially to the supercritical regime. Ideal gas law becomes invalid. In order to try to capture the average characteristics of this combustion process, numerical computations are performed using a model based on a one-phase multi-component approach. Such work requires fluid properties and a correct definition of the mixture behavior generally described by cubic equations of state with appropriated thermodynamic relations validated against the NIST data. In this study we consider an alternative way to get the effect of real gas by testing the volume-weighted-mixing-law with association of the component transport properties using directly the NIST library data fitting including the supercritical regime range. The numerical simulations are carried out using 3D RANS approach associated with two tested turbulence models, the standard k-Epsilon model and the realizable k-Epsilon one. The combustion model is also associated with two chemical reaction mechanisms. The first one is a one-step generic chemical reaction and the second one is a two-step chemical reaction. The obtained results like temperature profiles, recirculation zones, visible flame lengths and distributions of OH species are discussed.

关键词： Rocket engine non-premixed combustion supercritical regime H2-O2 flame transport properties

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A QUASILINEAR SINGULAR ELLIPTIC SYSTEM WITHOUT COOPERATIVE STRUCTURE

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Acta Mathematica Scientia 2014年第3期34卷 905-916页

作者： Dumitru MOTREANU abdelkrim MOUSSAOUI Dpartement de Math'ematiques Universit'e de Perpignan66860 PerpignanFrance Biology Department A. Mira Bejaia UniversityTarga Ouzemour 06000 BejaiaAlgeria

In this article, we investigate the existence of positive solutions of a singular quasilinear elliptic system for which the cooperative structure is not required. The approach is based on the Schauder fixed point theo... 详细信息

关键词： Singular system p-Laplacian, Schauder's fixed point theorem bounded solution Moser iteration

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Adaptive Fault Tolerant Control of Multi-time-scale Singularly Perturbed Systems

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International Journal of Automation and computing 2018年第6期15卷 736-746页

作者： Adel Tellili Nouceyba abdelkrim Amina Challouf Mohamed Naceur abdelkrim Research Unit MACS University of Gabes Gabes Tunisia Higher Institute of Industrial Systems at Gabes University of Gabes Gabes Tunisia Higher Institute of Technological Studies at Djerba Djerba Tunisia National School of Engineers of Gabes University of Gabes Gabes Tunisia

This paper studies the fault tolerant control, adaptive approach, for linear time-invariant two-time-scale and three-time-scale singularly perturbed systems in presence of actuator faults and external disturbances. First, the full order system will be controlled using v-dependent control law. The corresponding Lyapunov equation is ill-conditioned due to the presence of slow and fast phenomena. Secondly, a time-scale decomposition of the Lyapunov equation is carried out using singular perturbation method to avoid the numerical stiffness. A composite control law based on local controllers of the slow and fast subsystems is also used to make the control law ε-independent. The designed fault tolerant control guarantees the robust stability of the global closed-loop singularly perturbed system despite loss of effectiveness of actuators. The stability is proved based on the Lyapunov stability theory in the case where the singular perturbation parameter is sufficiently small. A numerical example is provided to illustrate the proposed method.

关键词： Singularly perturbed systems time scale decomposition adaptive fault tolerant control actuator fault Lyapunov equations

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A formal model for plastic human computer interfaces

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Frontiers of Computer Science 2018年第2期12卷 351-375页

作者： abdelkrim CHEBIEB Yamine AIT AMEUR Computer Science School for Engineers (ESI) Algiers 16270 Algeria IRIT-INPT-ENSEEIHT Toulouse 31071 France

The considerable and significant progress achieved in the design and development of new interaction devices between man and machine has enabled the emergence of various powerful and efficient input and/or output devices. Each of these new devices brings specific interaction modes. With the emergence of these devices, new interaction techniques and modes arise and new interaction capabilities are offered. New user interfaces need to be designed or former ones need to evolve. The design of so called plastic user interfaces contributes to handling such evolutions. The key requirement for the design of such a user interface is that the new obtained user interface shall be adapted to the application and have, at least, the same behavior as the previous （adapted） one. This paper proposes to address the problem of user interface evolution due to the introduction of new interaction devices and/or new interaction modes. More, precisely, we are interested by the study of the design process of a user interface resulting from the evolution of a former user interface due to the introduction of new devices and/or new interaction capabilities. We consider that interface behaviors are described by labelled transition systems and comparison between user interfaces is handled by an extended definition of the bi-simulation relationship to compare user interface behaviors when interaction modes are replaced by new ones.

关键词： formal modeling and verification ontology based modeling plastic user interfaces adaptive systems

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EXISTENCE AND BOUNDEDNESS OF SOLUTIONS FOR SYSTEMS OF QUASILINEAR ELLIPTIC EQUATIONS

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Acta Mathematica Scientia 2021年第2期41卷 397-412页

作者： abdelkrim MOUSSA OUI Jean VELIN Applied Mathematics Laboratory Faculty of Exact SciencesA.Mira Bejaia UniversityAlgeria Département de Mathématiques et Informatique Laboratoire LAMIAUniversitédes AntillesCampus de Fouillole 97159 Pointe-à-PitreGuadeloupe(FWI)

This article sets forth results on the existence and boundedness of solutions for quasilinear elliptic systems involving p-Laplacian and q-Laplacian *** approach combines Schaefer's fixed point as well as Moser's iter... 详细信息

关键词： p-Laplacian Schaefer's fixed point Besov and Sobolev spaces boundedness regularity

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A renewal theory based performance and configuration framework of the IEEE 802.11ah RAW mechanism

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Digital Communications and Networks 2023年第1期9卷 236-251页

作者： Hamid Taramit Luis Orozco-Barbosa abdelkrim Haqiq Hassan First University of Settat Faculty of Sciences and TechniquesComputerNetworksMobility and Modeling Laboratory:IR2M26000 SettatMorocco Albacete Research Institute of Informatics Universidad de Castilla-La Mancha02006 AlbaceteSpain

IEEE 802.11ah is a new Wi-Fi standard for sub-1Ghz communications,aiming to address the challenges of the Internet of Things(IoT).Significant changes in the legacy 802.11 standards have been proposed to improve the network performance in high contention scenarios,the most important of which is the Restricted Access Window(RAW)*** mechanism promises to increase the throughput and energy efficiency by dividing stations into different *** this scheme,only the stations belonging to the same group may access the channel,which reduces the collision probability in dense ***,the standard does not define the RAW grouping *** this paper,we develop a new mathematical model based on the renewal theory,which allows for tracking the number of transmissions within the limited RAW slot contention period defined by the *** then analyze and evaluate the performance of RAW *** also introduce a grouping scheme to organize the stations and channel access time into different groups within the ***,we propose an algorithm to derive the RAW configuration parameters of a throughput maximizing grouping *** additionally explore the impact of channel errors on the contention within the time-limited RAW slot and the overall RAW optimal *** presented analytical framework can be applied to many other Wi-Fi standards that integrate periodic channel *** simulations using the MATLAB software validate the analytical model and prove the effectiveness of the proposed RAW configuration scheme.

关键词： IEEE 802.11ah Performance evaluation Renewal theory RAW mechanism Internet of things

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A Real Time Self-Tuning Motion Controller for Mobile Robot Systems

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IEEE/CAA Journal of Automatica Sinica 2019年第1期6卷 84-96页

作者： Mohamed Boukens abdelkrim Boukabou Mohammed Chadli the Department of Electronics University of Laghouat IEEE the Department of Electronics University of MSB Jijel University of Picardie Jules Verne

This paper proposes an intelligent controller for motion control of robotic systems to obtain high precision tracking without the need for a real-time trial and error *** addition, a new self-tuning algorithm has been developed based on both the ant colony algorithm and a fuzzy system for real-time tuning of controller parameters. Simulations and experiments using a real robot have been addressed to demonstrate the success of the proposed controller and validate the theoretical analysis. Obtained results confirm that the proposed controller ensures robust performance in the presence of disturbances and parametric uncertainties without the need for adjustment of control law parameters by a trial and error method.

关键词： Learning and adaptive systems motion control metaheuristic robust control real-time tuning self-tuning wheeled mobile robot

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