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Communications and Network 2014年第3期6卷 155-164页

作者： mohammed m. Olama seddik m. djouadi Charalambos D. Charalambous Computational Sciences and Engineering Division Oak Ridge National Laboratory Oak Ridge USA Department of Electrical and Computer Engineering University of Cyprus Nicosia Cyprus Department of Electrical Engineering and Computer Science University of Tennessee Knoxville USA

Wireless networks are characterized by nodes mobility, which makes the propagation environment time-varying and subject to fading. As a consequence, the statistical characteristics of the received signal vary continuously, giving rise to a Doppler power spectral density (DPSD) that varies from one observation instant to the next. This paper is concerned with dynamical modeling of time-varying wireless fading channels, their estimation and parameter identification, and optimal power control from received signal measurement data. The wireless channel is characterized using a stochastic state-space form and derived by approximating the time-varying DPSD of the channel. The expected maximization and Kalman filter are employed to recursively identify and estimate the channel parameters and states, respectively, from online received signal strength measured data. moreover, we investigate a centralized optimal power control algorithm based on predictable strategies and employing the estimated channel parameters and states. The proposed models together with the estimation and power control algorithms are tested using experimental measurement data and the results are presented.

关键词： Wireless Networks Time-Varying Wireless Fading Channel Impulse Response Doppler Power Spectral Density Stochastic State-Space model Stochastic modeling Optimal Power Control Expectation maximization Kalman Filter

Cooling enhancement of planar-balanced magnetron cathode

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Nuclear Science and Techniques 2017年第8期28卷 69-74页

作者： m'hamed Salhi seddik El Hak Abaidia Brahim mohamedi Sofiane Laouar Centre de Recherche Nucleaire de Birine B.P. 18017200 Ain-Oussera Algeria Unite de Recherche mPE Faculte des Sciences de l'Ingenieur Universite M'hamed Bougarra de Boumerdes 35000 Boumerdes Algeria

In physical vapor deposition on a magnetron cathode, temperature of sensitive components must be kept under threshold limit, so as to ensure the cathode reliability,the process reproducibility, and the best quality of thin *** can be achieved by an adequate design to enhance the dissipation of heat generated at the cathode. In this paper,temperature distribution and streamlines velocity of the cathode coolant inside a cathode magnetron are analyzed by using CFD solver ANSYS FLUENT in the single-phase method in combination with k–e standards turbulent *** results show that the design is appropriate under the calculation parameters, and for high heat densities some improvements are necessary to enhance heat dissipation and keep temperature under the threshold limit.

关键词：阴极冷却强化磁控平衡平面物理气相沉积 FLUENT 温度分布

Coverless Image Steganography Based on Jigsaw Puzzle Image Generation

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Computers, materials & Continua 2021年第5期67卷 2077-2091页

作者： Al Hussien seddik Saad m.S.mohamed E.H.Hafez Department of Computer Science Faculty of ScienceMinia UniversityMinya61519Egypt Department of mathematics College of ScienceTaif UniversityTaif21944Saudi Arabia Department of mathematics Faculty of ScienceAl-Azher UniversityNasr City11884Egypt Department of mathematics Faculty of ScienceHelwan UniversityCairoEgypt

Current image steganography methods are working by assigning an image as a cover file then embed the payload within it by modifying its pixels,creating the stego ***,the left traces that are caused by these modifications will make steganalysis algorithms easily detect the hidden payload.A coverless data hiding concept is proposed to solve this *** does not mean that cover is not required,or the payload can be transmitted without a ***,the payload is embedded by cover generation or a secret message mapping between the cover file and the *** this paper,a new coverless image steganography method has been proposed based on the jigsaw puzzle image generation driven by a secret ***,the image is divided into equal rows then further divided into equal columns,creating blocks(i.e.,sub-images).Then,according to secret message bits and a proposed mapping function,each block will have tabs/blanks to get the shape of a puzzle piece creating a fully shaped jigsaw puzzle *** that,the generated jigsaw puzzle image is sent to the *** results and analysis show a good performance in the hiding capacity,security,and robustness compared with existing coverless image steganography methods.

关键词： Coverless information hiding Jigsaw puzzle image image steganography data hiding

Structural and morphological characterizations of ZnO nanopowder synthesized by hydrothermal route using inorganic reactants

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Journal of Semiconductors 2014年第12期35卷 8-12页

作者： D.djouadi m.meddouri A.Chelouche L.Hammiche A.Aksas Laboratoire de Génie de l'Environnement(LGE) Université de Béjaia Algérie

Zinc oxide nanoscale powder has been synthesized by a hydrothermal route using zinc sulfate and sodium hydroxide. The as-prepared powder was annealed at 600 ℃ for 2 h and then characterized by X-ray diffraction（XRD）, scanning electron microscopy and infra-red Fourier transformed spectroscopy. XRD measurements have shown a Zn O hexagonal wurtzite polycrystalline structure with good crystallinity and the formation of a new sodium pyrosulfate phase in the as-prepared powder. The annealing improves the crystalline quality of the powder and transforms the sodium pyrosulfate phase to a sodium sulfate one. The thermal treatment does not affect the lattice parameters and the Zn–O bond length but improves the random orientation of the Zn O crystallites *** O crystallites have an interconnected-nano-needles morphology forming irregular shaped aggregates. The size of the crystallites is about 20 nm. EDX analysis has shown the presence of C and S in addition to Zn and O. FTIR spectra confirm the formation of Zn O and sodium sulfate. The synthesized Zn O powder has a very high crystalline quality and the used method is a very advantageous one for the fabrication of nanosized metal oxides from inorganic reactants for photo-catalysis applications.

关键词： Zn O hydrothermal method zinc sulfate nanoneedles DRX SEm FTIR

Electrodes based on nano-tree-like vanadium nitride and carbon nanotubes for micro-supercapacitors

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Journal of materials Science & Technology 2018年第6期34卷 976-982页

作者： Nadir Ouldhamadouche Amine Achour Raul Lucio-Porto mohammad Islam Shahram Solayman Ali Arman Azin Ahmadpourian Hamed Achour Laurent Le Bri-zoual mohamed Abdou djouadi Thierry Brousse Laboratoire de Génie Physique Université lbn Khaldoun BP P 78 Zaaroura 14000 Tiaret Algeria National Institute of Scientific Research 1650 Bd. Lionel-Boulet Varennes QCJ3X1P7 Canada Universidad Autónoma de Nuevo León Facultad de lngeniería Mecdnica y Eléctrica San Nicolas de los Garza 66450 Nuevo León Mexico Universidad Autónoma de Nuevo León Centro de lnnovación Investigación y Desarrollo en lngeniería y Tecnología Apodaca 66600 Nuevo León Mexico Deanship of Scientific Research Advanced Manufacturing Institute King Saud University P.O. Box 800 Riyadh 11421 Saucli Arabia Department of Physics Science and Research Branch Islamic Azad University Tehran Iran Vacuum Technology Group ACECR Sharif Branch Tehrun Iran Young Researchers and Elite Club Arak Branch Islamic Azad University Arak Iran Institute of Condensed matter Physics Ecole Polytechnique Fédérale de Lausanne (EPFL) CH-1015 Lausanne Switzerland University of Rennes 1 Institut d'Electronique et de Télécommunications IETR - UMR CNRS 6164 Campus de Beaulieu -Bat 11D 263 Av General Leclerc 35042 Rennes cedex France Institut des materiauxJean Rouxel (ImN) Universite de Nantes CNRS 2 rue de la Houssiniere BP32229 44322 Nantes Cedex 3 France Reseau sur le Stockage Electrochimique de l'Energie (RS2E) FR CNRS 3459 France

Vanadium nitride （VN） was deposited by DC-sputtering on a vertically aligned carbon nanotube （CNTs） template for the purpose of nano-structuration. This led to the fabrication of hierarchically composite electrodes consisting of porous and nanostructured VN grown on vertically aligned CNTs in a nano-treelike configuration for micro-supercapacitor application. The electrodes show excellent performance with an areal capacitance as high as 37.5 mF cm^-2 at a scan rate of 2 mV s^-1 in a 0.5 m K2504 mild electrolyte solution. Furthermore, the capacitance decay was only 15% after 20,000 consecutive cycles. moreover, the capacitance was found to increase with VN deposit thickness. The X-ray photoelectron spectroscopy analyses of the electrodes before and after cycling suggest that the oxide layers that form at the VN surface is the responsible for the redox energy storage in this material. Such electrodes can compete with other transition metal nitride based electrodes for micro-supercapacitors.

关键词： Vanadium nitride CNTs micro-supercapacitors Surface chemistry

mICROmEGAS Signal: Numerical Simulation Based on Neon-Isobutane and Neon-DmE

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modern Instrumentation 2015年第1期4卷 1-9页

作者： Hamid mounir seddik Bri Spectrometry Laboratory of materials and Archaeomaterials (LASmAR) Faculty of Science University Moulay Ismail Meknes Morocco Electrical Engineering Departments High School of Technology ESTM University My Ismail Meknes Morocco

Recent years, we have seen the development of many fields of gas detectors. The mICROmEGAS (micro-mesh Gas Structure) appeared as the very promising detector. It is a major family of position detectors in High Energy Physics. This work is done in normal (NTP) based gas mixtures: neon are noble gas and isobutane and DmE (dimethyl-ether) as moderators gas (quenchers), using 55Fe as a radiation source (X-ray 5.9 keV). To address the modeling of mICROmEGAS detector, a descriptive model of different physical and geometrical phenomena mICROmEGAS was established by developing a simulation program to spreading the detector response. After, an analytical calculation of the potential and the electric field distributions has been presented briefly, to better estimate electrical and geometric configuration. Finally, simulation results of electrical signals based on gas mixtures (Neon-isobutane, Neon-DmE) produced by mICROmEGAS were presented and analyzed in order to improve the mICROmEGAS performance (spatial (12 μm) and temporal (0.7 ns) resolutions).

关键词： mICROmAEGAS Gas mixture X-Ray Source Avalanche Phenomenon mATLAB Programing Signal

First-Order Studies of Nanometric Biferroic

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World Journal of Condensed matter Physics 2012年第2期2卷 66-74页

作者： m. A. Ahmed U. seddik N. G. Imam materials Science Lab.(1) Physics Department Faculty of Science Cairo University Giza Egypt Physics Department Nuclear Research Center Atomic Energy Authority Cairo Egypt

magnetoelectric biferroic nanocomposite with composition 0.5Ni0.5Zn0.5Fe2O4 + 0.5BaTiO3 was synthesized by ceramic technique. The structural and electrical characterizations of the investigated nanocomposite are discussed and reported. The formation of nanosized composite with two separate phases was confirmed by X-ray diffraction, scanning electron microscopy (SEm) and Fourier transform infrared spectroscopy (FT-IR). The variation of dielectric constant (ε'), dielectric loss factor (ε') and the ac conductivity (σac) of 0.5Ni0.5Zn0.5Fe2O4 + 0.5BaTiO3 was investigated as a function of both frequency and temperature. Thermal hysteresis (first-order transition) was obtained during heating (300 - 830 K) and cooling runs (830 - 300 K). The exact transition temperature and the amount area of the thermal hysteresis depend on applied ac electric field. The delay (lagging) time between heating and cooling processes was esti-mated from the hysteresis loop area versus frequency. The conduction mechanism in the investigated samples was explained according to different models. This study enhances the use of this prepared system in memory applications.

关键词： Biferroic Nanocomposite Nickel-Zinc Ferrite Barium Titanate Dielectric Hysteresis First-Order Transition

Optimal m-BCJR Turbo Decoding: The Z-mAP Algorithm

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Wireless Engineering and Technology 2011年第4期2卷 230-234页

作者： Aissa Ouardi Ali Djebbari Boubakar seddik Bouazza 不详

In this paper, we propose a novel idea for improvement performances of the leader m-BCJR algorithm functioning in low complexity. The basic idea consists to localize error instant possibility, and then increase the complexity around this moment. We also propose an easy and important idea for early localisation of erroneous moments. We call this new algorithm Z-mAP. The simulations show that the improvement of performances is significant. The performances of Z-mAP turbo decoding are so close to full mAP-BCJR performances. Furthermore, the complexity is the same that of the m-BCJR. So, Z-mAP is an optimal version of m-BCJR algorithm.

关键词： mAP-BCJR Algorithm m-BCJR Turbo Decoding Complexity Reduction Error Localisation Criterion

Non Linear magnetic Hysteresis modelling by Finite Volume method for Jiles-Atherton model Optimizing by a Genetic Algorithm

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Journal of Electromagnetic Analysis and Applications 2011年第6期3卷 191-198页

作者： seddik Azzaoui Kamel Srairi mohamed El Hachemi Benbouzid 不详

This paper describes a generalization methodology for nonlinear magnetic field calculation applied on two-dimensional (2-D) finite Volume geometry by incorporating a Jiles-Atherton scalar hysteresis model. The scheme is based upon the definition of modified governing equation derived from maxwell’s equations considered the magnetization m. This paper shows how to extract optimal parameters for the Jiles-Atherton model of hysteresis by a real coded genetic algorithm approach. The parameters identification is performed by minimizing the mean squared error between experimental and simulated magnetic field curves. The calculated results are validated by experiences performed in an SST’s frame.

关键词： magnetic Hysteresis Jiles-Atherton model Genetic Algorithm Optimization Parameters Identification Finite Volume method (FVm)