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Effect of driving frequency on electron heating in capacitively coupled RF argon glow discharges at low pressure

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Chinese Physics B 2017年第11期26卷 329-337页

作者： Tagra samir 刘悦赵璐璐周艳文 Key Laboratory of Materials Modification by Laser Ion and Electron Beams Ministry of Education School of PhysicsDalian University of Technology School of Information Science and Engineering Dalian Polytechnic University School of Materials & Metallurgy University of Science & Technology

A one-dimensional（1D） fluid model on capacitively coupled radio frequency（RF） argon glow discharge between parallel-plates electrodes at low pressure is established to test the effect of the driving frequency on electron heating. The model is solved numerically by a finite difference method. The numerical results show that the discharge process may be divided into three stages： the growing rapidly stage, the growing slowly stage, and the steady stage. In the steady stage,the maximal electron density increases as the driving frequency increases. The results show that the discharge region has three parts： the powered electrode sheath region, the bulk plasma region and the grounded electrode sheath region. In the growing rapidly stage（at 18 μs）, the results of the cycle-averaged electric field, electron temperature, electron density, and electric potentials for the driving frequencies of 3.39, 6.78, 13.56, and 27.12 MHz are compared, respectively. Furthermore,the results of cycle-averaged electron pressure cooling, electron ohmic heating, electron heating, and electron energy loss for the driving frequencies of 3.39, 6.78, 13.56, and 27.12 MHz are discussed, respectively. It is also found that the effect of the cycle-averaged electron pressure cooling on the electrons is to ＂cool＂ the electrons; the effect of the electron ohmic heating on the electrons is always to ＂heat＂ the electrons; the effect of the cycle-averaged electron ohmic heating on the electrons is stronger than the effect of the cycle-averaged electron pressure cooling on the electrons in the discharge region except in the regions near the electrodes. Therefore, the effect of the cycle-averaged electron heating on the electrons is to ＂heat＂ the electrons in the discharge region except in the regions near the electrodes. However, in the regions near the electrodes, the effect of the cycle-averaged electron heating on the electron is to ＂cool＂ the electrons. Finally, the space distributions of the electron

关键词： capacitively coupled plasmas electron heating radio frequency(RF) glow discharges driving frequency

Stabilizing soft clay using geo-foam beads and cement bypass dust

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Underground Space 2020年第4期5卷 292-297页

作者： Essam Farouk Badrawi Mahmoud samir El-kady Structural Engineering Department Faculty of EngineeringZagazig UniversityEgypt Civil Engineering Department Jouf UniversitySaudi Arabia

Soft clays are usually classified according to their undrained shear strength,*** of Su less than 12.5 kPa are associated with very soft *** addition to their low shear strength,soft clays exhibit high compressibility upon ***,soft clays are considered to be problematic for foundation ***-foam is an industrial material that is characterized by a very low unit weight(20 kg/m^(3) on average)compared to that of the *** density of expanded polystyrene(EPS)ranges from 1.0%to 2.5%,which results in a compressive strength ranging between 70 kPa and 140 kPa and an elastic modulus ranging between 5 MPa and 12 *** geofoam blocks are used in a wide range of geotechnical applications as a lightweight fill *** main objective of this study was to investigate the geotechnical properties of soft clays containing geo-foam beads and cement bypass dust(CBPD).We also investigated the viability of preparing low-strength excavatable fill *** study the effect of(geofoam beads+CBPD)/soft clay on the fluid-state and hardened properties of new fill,we conducted experiments on two groups of mixtures(A&B).Each mixture contained different ratios of geo-foam beads and CBPD so that we could study the effect of the additive on the flow consistency,dry unit weight,unconfined compressive strength,and shear strength of the *** test results showed that the unconfined compressive strength of the studied mixtures without geo-foam ranged from 271.8 kPa to 1405.14 kPa at CBPD concentrations between 3.88%and 18.63%.The cohesion values for the group containing geo-foam ranged from 50 kPa to 20 kPa at geo-foam percentages between 0.32%and 1.35%.The friction angle of the group containing geo-foam ranged from 10 kPa to 22 kPa at CBPD percentages between 0.32%and 1.35%.Cement bypass dust can be successfully used to process self-compacting,self-leveling,excavatable and flowable fill material.

关键词： Geo-foam beads Cement bypass dust Flowable fill Shear strength

An attractive analytical technique for coupled system of fractional partial differential equations in shallow water waves with conformable derivative

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Communications in Theoretical Physics 2020年第8期72卷 1-17页

作者： Mohammed Al-Smadi Omar Abu Arqub samir Hadid Department of Applied Science Ajloun CollegeAl-Balqa Applied UniversityAjloun 26816Jordan Department of Mathematics Faculty of ScienceAl-Balqa Applied UniversitySalt 19117Jordan Department of Mathematics and Sciences College of Humanities and SciencesAjman UniversityAjmanUnited Arab Emirates

Mathematical simulation of nonlinear physical and abstract systems is a very vital process for predicting the solution behavior of fractional partial differential equations(FPDEs)corresponding to different applications in science and engineering. In this paper, an attractive reliable analytical technique, the conformable residual power series, is implemented for constructing approximate series solutions for a class of nonlinear coupled FPDEs arising in fluid mechanics and fluid flow, which are often designed to demonstrate the behavior of weakly nonlinear and long waves and describe the interaction of shallow water waves. In the proposed technique the n-truncated representation is substituted into the original system and it is assumed the(n-1) conformable derivative of the residuum is zero. This allows us to estimate coefficients of truncation and successively add the subordinate terms in the multiple fractional power series with a rapidly convergent form. The influence, capacity, and feasibility of the presented approach are verified by testing some real-world applications. Finally, highlights and some closing comments are attached.

关键词： nonlinear coupled system fractional partial differential equations residual power series method conformable fractional derivative

Direct fractional order MRAC adaptive control design for a class of fractional order commensurate linear systems

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Journal of Control and Decision 2021年第3期8卷 363-371页

作者： Hanane Balaska samir Ladaci Abdelbaki Djouambi Department of Electrical Engineering LGEA LaboratoryUniversity of Oum El BouaghiOum El BouaghiAlgeria Department of E.E.A. National Polytechnic School of ConstantineConstantineAlgeria SP-LAB Signal Processing Laboratory UMC1 UniversityConstantineAlgeria

In this paper,we introduce a direct fractional order adaptive control design based on model reference adaptive control(MRAC)structure for a class of commensurate fractional order linear systems with an arbitrary relative degree,and whose parameters are *** generalising the application of standard direct MRAC strategy to plants described by fractional order models,we develop a fractional adaptive control scheme(FOMRAC)based on the output *** also define an adaptation control law ensuring the stability of the closed-loop system and the good tracking of the reference *** asymptotic stability of the fractional order control system is proven using an extension of the Lyapunov *** results show the effectiveness of the proposed control method even for plants with model parametric variations and additive noises.

关键词： Fractional order linear commensurate system direct model reference adaptive control fractional adaptive control direct FOMRAC Lyapunov stability

Application of polymeric flocculant for enhancing settling of the pond ash particles and water drainage from hydraulically stowed pond ash

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International Journal of Mining Science and Technology 2013年第1期23卷 21-26页

作者： Mishra Devi Prasad Das samir Kumar Department of Mining Engineering Indian School of Mines Dhanbad 826004 India National Institute of Technology Jalandhar Jalandhar 144011 India

Delayed settling of the ash particles and poor drainage of water from the pond ash are the major problems faced during the hydraulic stowing of pond ash. In this study the effect of polymeric flocculant on settling of the ash particles and drainage of water during pond ash stowing are investigated. In addition, the parameters, viz. drainage and absorption of water during pond ash stowing are quantified by stowing a mine goaf model with pond ash slurries of five different concentrations added with and without flocculant. The study revealed that addition of only 5 10 6 of Sodium Carboxymethyl Cellulose (Na-CMC) flocculant with the pond ash slurries during stowing offers best result in terms of quicker settling of the ash particles and enhanced water drainage from the hydraulically stowed pond ash. Besides, it resulted in drainage of more than 85% of the total water used in the initial 45 min of stowing. The improvement in drainage is caused due to coagulation and flocculation of the pond ash particles because of charge neutralization and particle-particle bridging. This study may provide a basis for estimating the drainage and absorption of water during the real pond ash stowing operation in underground mines.

关键词： Fly ash Pond ash Stowing Settling Water drainage Polymeric flocculant

Selective and complementary use of Optical Coherence Tomography and Fluorescein Angiography in retinal practice

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Eye and Vision 2016年第1期3卷 202-210页

作者： samir S.Shoughy Igor Kozak The Eye Center and The Eye Foundation for Research in Ophthalmology PO Box 55307Riyadh 11534Saudi Arabia King Khaled Eye Specialist Hospital RiyadhSaudi Arabia

The current field of posterior pole and retinal imaging of the human eye has expanded into detailed analyses of the macula,retinal periphery,individual retinal layers,vitreoretinal interface,imaging of the choroid and the optic nerve *** challenge in retinal imaging is the enduring pursuit of deeper penetration into tissues,increased resolution to the cellular level,and interpretation of *** much deeper can we go and with what resolution and reproducibility?These are fundamental questions for experts in search of novel imaging *** discoveries may resolve existing controversies,but inevitably stimulate new *** technologies in retinal imaging include adaptive optics retinal imaging and optical coherence tomography-based retinal *** this review,the focus of our discussion will be the discrepancy between the findings(interpretation)of one imaging technology that do not agree or are not even found with a complementary *** a clearly seen abnormality is present with one technology but absent in another,what are the possible explanations?Following is a summary of key concepts of retinal and optic nerve imaging modalities and current controversies regarding their interpretation and/or limitations.

关键词： Retina Imaging Optical coherence tomography Fluorescein angiography

Development of Magnetite/Graphene Oxide Hydrogels from Agricultural Wastes for Water Treatment

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Journal of Renewable Materials 2022年第7期10卷 1889-1909页

作者： Hebat-Allah STohamy Mohamed El-Sakhawy samir Kamel Cellulose and Paper Department National Research CentreCairo12622Egypt

A novel magnetic hydrogel loaded with graphene oxide(GO)was developed in this ***,GO was prepared from bagasse through a single step via oxidation in the presence of ferrocene under muffled atmospheric conditions,followed by the loading of different amounts of magnetite onto GO via co-precipitation reaction of iron onto GO ***,the 2-acrylamido-2-methyl-1-propane sulfonic acid was grafted onto carboxymethyl cellulose in the presence of magnetite GO and N,N′-methylenebisacrylamide as crosslinker yielded *** structure,morphological,and thermal behavior of the prepared hydrogels were *** addition,the adsorption performance of Ni(Ⅱ)ions from aqueous media by the prepared hydrogels was investigated as a function of temperature,time,and concentration of adsorbate in a batch *** results demonstrated a remarkable enhancement in the adsorption process of Ni(Ⅱ)(Removal efficiency=98.82%).All isotherms were found to fit the Langmuir model *** adsorption properties of both magnetic GO and magnetic hydrogel showed promising properties as green and cheap adsorbents.

关键词： Magnetite graphene oxide hydrogel Ni(Ⅱ)adsorption kinetic models thermodynamics

Alcohol,inflammation,and gut-liver-brain interactions in tissue damage and disease development

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World Journal of Gastroenterology 2010年第11期16卷 1304-1313页

作者： H Joe Wang samir Zakhari M Katherine Jung Division of Metabolism and Health Effects National Institute on Alcohol Abuse and Alcoholism National Institutes of Health

Chronic inflammation is often associated with alcoholrelated medical conditions. The key inducer of such inflammation, and also the best understood, is gut microflora-derived lipopolysaccharide (LPS). Alcohol can significantly increase the translocation of LPS from the gut. In healthy individuals, the adverse effects of LPS are kept in check by the actions and interactions of multiple organs. The liver plays a central role in detoxifying LPS and producing a balanced cytokine milieu. The central nervous system contributes to anti-inflammatory regulation through neuroimmunoendocrine actions. Chronic alcohol use impairs not only gut and liver functions, but also multi-organ interactions, leading to persistent systemic inflammation and ultimately, to organ damage. The study of these interactions may provide potential new targets for therapeutic intervention.

关键词： Chronic alcohol use Chronic inflammation Li- popolysaccharides Pro-inflammatory and anti-inflammatory cytokines Kupffer cells Monocytes Tumor necrosis factor α Interleukin-10 Neuroendocrine Hypothalamo-pituitary-adrenal axis Glucocorticoid

Comments on process of duplex coatings on aluminum alloys

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Journal of Central South University of Technology 2004年第3期11卷 239-245页

作者： samir H.A. 钱翰城夏伯才吴仕明 School of Mechanical Engineering Chongqing University Chongqing 400044 China

Despite the great achievements made in improvement of wear resistance properties of aluminum alloys, their applications in heavy surface load-bearing are limited. Single coating is insufficient to produce the desired combination of surface properties. These problems can be solved through the duplex coatings. The aim of the present study is to overview the research advances on processes of duplex coatings on (aluminum) alloys combined with micro plasma oxidation process and with other modern processes such as physical vapour deposition and plasma assisted chemical vapour deposition and also to evaluate the performance of micro plasma oxidation coatings in improving the load-bearing, friction and wear resistance properties of aluminum alloys in comparison with other coatings. Wherein, a more detailed presentation of the processes and their performances and disadvantages are given as well.

关键词： aluminum alloy duplex coating micro plasma oxidation physical vapour deposition plasma assisted chemical vapour deposition tribological property