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Journal of Rare Earths 2014年第1期32卷 37-42页

作者： m.m.S.Sanad m.m.Rashad E.A.Abdel-Aal m.F.El-Shahat K.Powers Central metallurgical R & D Institute Particle Engineering Research Center University of Florida Faculty of Science Ain Shams University

Dielectric ceramics of m（x）Al6（1-x）Si2O13 doped mullite were synthesized via co-precipitation technique. The X-ray diffrac-tion profiles revealed that these nanoparticles were crystallized well and the volume of mullite unit cell was increased as a function of the ionic radius of dopant ion. TEm images showed regular orthorhombic crystal morphology for the pure mullite sample. meanwhile, the doped samples exhibited slightly distorted crystal morphology of larger particle sizes. DSC thermograms evinced that the exo-thermic peak temperature of mullite was shifted to the lower value with m3＋ion insertion. The photoluminescence spectra were stud-ied for mullite samples, and it was found that the intensity of the emission spectra was affected by the m3＋ion type. It was found that, Y3＋doped mullite achieved the minimum dielectric loss value of 0.01 in the radio wave frequency region （1 mHz）. meanwhile, Gd3＋doped mullite achieved the minimum dielectric loss value of 0.09 in the microwave frequency region （1 GHz）.

关键词： rare earths doped mullite photoluminescence crystallization temperature dielectric ceramics

The performance of a dissipative electrooptomechanical system using the Caldirola–Kanai Hamiltonian approach

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Communications in Theoretical Physics 2023年第7期75卷 123-131页

作者： m m Atabaki m K Tavassoly A Behjat m Hassani Nadiki K Javidan Optics and Laser Group Faculty of PhysicsYazd UniversityYazdIran Department of Physics School of SciencesFerdowsi University of MashhadMashhad 91775-1436Iran

By combining all optical,electronic,and mechanical capabilities,electro-optomechanical systems,along with the use of mechanical displacement,the conversion of low-frequency electrical signals into much higher-frequency optical signals is *** process provides several capabilities that have very important applications in various fields,including classical,as well as quantum *** this regard,the inevitable effect of dissipation on the performance indicators of such systems is one of the important issues affecting its *** approach for investigating the effect of dissipation is based on a time-dependent Hamiltonian has been known as the Caldirola-Kanai(CK)Hamiltonian,wherein the exponentially increasing mass,i.e.m(t)=m0(eγt)enters the mechanical oscillator *** this approach shows that,the performance of the system under the influence of dissipation with CK Hamiltonian formalism,in which the dissipation terms are embedded in the Hamiltonian,are more logical,analytical,and reliable than considering the effect of dissipation with the phenomenological method(including the dissipation effects in the equations of motion by hand),which has been recently used in Bagci et al.(Nature,507,81,2014).In our method,it is also possible to monitor the performance of the system via the adjustment of dissipation components,i.e.,resistance R and reactance L(and CK damping parameterγ)in the electrical(mechanical membrane)part of the system.

关键词： dissipative system electro-optomechanical system Caldirola-Kanai Hamiltonian

Gas pressure effect on plasma transport in a magnetic-filtered radio-frequency plasma source

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Plasma Science and Technology 2020年第6期22卷 103-109页

作者： N OUDINI m m ALIm R TADJINE A BENDIB Laboratoire des Plasmas de Décharges Centre de Développement des Technologies AvancéesCitédu 20 Aout BP 17 Baba Hassen16081 AlgiersAlgeria Laboratoire d’Electronique Quantique Facultéde PhysiqueUSTHBEl Alia BP 32Bab Ezzouar 16111AlgiersAlgeria

Volume negative ion production relies on a magnetic filter(mF),where the plasma downstream of the mF is characterized by a strip-like pattern that consists of a bright and dense plasma *** this work,we study,in a radio-frequency plasma source,the effects of operating pressure on this *** investigation,conducted using a Langmuir probe,shows that the plasma uniformity might be controlled through the gas ***,the operating pressure determines on which hemi-cylinder(side of magnetic field lines)the strip *** side inversion of the high-density plasma hemi-cylinder is due to an inversion of an ambipolar electric field that changes the E?×?B drift direction.

关键词： magnetic filter radio-frequency plasma source Langmuir probe E×B drift ambipolar electric field

Computational analysis for fractional characterization of coupled convection-diffusion equations arising in mHD fows

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Applied mathematics and mechanics(English Edition) 2023年第4期44卷 669-692页

作者： m.HAmID m.USmAN Zhenfu TIAN School of mathematics and Statistics Nanjing University of Information Science and TechnologyNanjing 210044China Department of Aeronautics and Astronautics Fudan UniversityShanghai 200433China School of mathematical Sciences Jiangsu UniversityZhenjiang 212013Jiangsu ProvinceChina

The work is devoted to the fractional characterization of time-dependent coupled convection-diffusion systems arising in magnetohydrodynamics(mHD)*** time derivative is expressed by means of Caputo’s fractional derivative concept,while the model is solved via the full-spectral method(FSm)and the semi-spectral scheme(SSS).The FSm is based on the operational matrices of derivatives constructed by using higher-order orthogonal polynomials and collocation *** SSS is developed by discretizing the time variable,and the space domain is collocated by using equal points.A detailed comparative analysis is made through graphs for various parameters and tables with existing *** contour graphs are made to show the behaviors of the velocity and magnetic *** proposed methods are reasonably efficient in examining the behavior of convection-diffusion equations arising in mHD flows,and the concept may be extended for variable order models arising in mHD flows.

关键词： higher-dimensional Chelyshkov polynomial(CP) time-dependent magneto-hydrodynamics(mHD)flow fractional convection-diffusion model convergence stability and error bound finite difference and higher-order scheme

Transient swelling-induced finite bending of hydrogel-based bilayers:analytical and FEm approaches

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Applied mathematics and mechanics(English Edition) 2023年第2期44卷 273-288页

作者： A.AmIRI m.BANIASSADI m.BAGHANI School of mechanical Engineering College of EngineeringUniversity of TehranTehran ***Iran

Hydrogels with their time-dependent intrinsic behaviors have recently been used widely in soft structures as sensors/*** of the most interesting structures is the bilayer made up of hydrogels which may undergo swelling-induced *** this work,by proposing a semi-analytical method,the transient bending of hydrogel-based bilayers is *** nonlinear solid mechanics,a robust semi-analytical solution is developed which captures the transient finite bending of hydrogel-based ***,the multiphysics model of the hydrogels is implemented in the finite element method(FEm) framework to verify the developed semi-analytical procedure *** effects of different material properties are investigated to illustrate the nonlinear behavior of these *** von-mises stress contour extracted from FEm shows that the critical area of these soft structures is at the interface of the layers which experiences the maximum stress,and this area is most likely to rupture in large deformations.

关键词： hydrogel transient swelling bilayer multiphysics finite bending

Analysis of the Biotribological Behavior for the Stainless Steel/Polyethylene Contact Using a Knee Prosthesis Simulator

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Journal of Bionic Engineering 2012年第1期9卷 59-65页

作者： m. Boujelbene S. Dhouibi m. Kharrat m. Dammak Laboratoire des Systkmes Electromeeaniques Ecole Nationale d＇Ingenieurs de Sfax Route de Soukra km 35 B.P. 1173 3038 Sfax Tunisia Institut Superieur de Gestion Industrielle de Sfax Route de Mharza Km 15 B.P. 954 3018 Sfax Tunisia Faeulte des Sciences de Gafsa Campus Universitaire Sidi Ahmed Zarrouk 2112 Gafsa Tunisia Institut Preparatoire aux Etudes d＇Ingenieurs de Sfax Route de Menzel Chaker Km 05 B.P. 1172 3018 Sfax Tunisia

In this work, a friction and wear simulator was used to reproduce the Anterior-Posterior （AP） sliding and the Flex- ion-Extension （FE） rotation generated in the knee joint during human gait cycle. We chose to simplify the contact geometry between the Total Knee Arthroplasty （TKA） femoral component and tibial insert. A 304L stainless steel cylinder which replaces the femoral component was loaded onto a flat High Density Polyethylene （HDPE） block which replaces the tibial insert. The tribological behavior of the considered contact was analyzed by tracking the number of cycles, the friction coefficient, the roughness of the wear track on HDPE, the HDPE weight loss and the damage mechanisms. The friction coefficient shows a gradual increase with the number of cycles for both AP and FE kinematics. The evolution of friction coefficient with the number of cycles is not affected by the value of the imposed normal load in the case of AP sliding. For the FE rotation, decreased friction coefficient is obtained when the imposed normal load increases. For both considered AP and FE kinematics, the roughness of the wear track on the HDPE is not affected by the imposed normal load. It shows a progressive decrease when the number of cycles increases. The wear of HDPE obeys the Archard law and the wear coefficient increases with the normal force. For a given value of normal load, the obtained wear coefficient for the AP sliding is larger than that obtained for FE rotation. A predominant adhesive wear mechanism was identified for both AP and FE kinematics. Under the same normal load, damage development in terms of plastic deformation, micro-cracking and debonding is more pronounced for the AP sliding if compared with the FE rotation. For a given kinematics, the damage severity increases with the normal load. This finding is in good agreement with the predicted values of the wear coefficient according to the Archard law.

关键词： knee prosthesis polyethylene friction wear gait cycle

Anomalous reactivity of thermo-bioconvective nanofluid towards oxytactic microorganisms

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Applied mathematics and mechanics(English Edition) 2020年第5期41卷 711-724页

作者： S.I.ABDELSALAm m.m.BHATTI Basic Science Department Faculty of EngineeringThe British University in EgyptAl-Shorouk CityCairo 11837Egypt Instituto de matemáticas-Juriquilla Universidad Nacional Autónoma de MéxicoBlvd.Juriquilla 3001Quer´etaro 76230M´exico College of mathematics and Systems Science Shandong University of Science and TechnologyQingdao 266590Shandong ProvinceChina

The peristaltic flow of a non-Newtonian nanofluid with swimming oxytactic microorganisms through a space between two infinite coaxial conduits is investigated. A variable magnetic field is applied on the flow. The bioconvection flow and heat transfer in the porous annulus are formulated, and appropriate transformations are used, leading to the non-dimensionalized ruling partial differential equation model. The model is then solved by using the homotopy perturbation scheme. The effects of the germane parameters on the velocity profile, temperature distribution, concentration distribution, motile microorganism profile, oxytactic profile, pressure rise, and outer and inner tube friction forces for the blood clot and endoscopic effects are analyzed and presented *** is noticed that the pressure rise and friction forces attain smaller values for the endoscopic model than for the blood clot model. The present analysis is believed to aid applications constituting hemodynamic structures playing indispensable roles inside the human body since some blood clotting disorders, e.g., haemophilia, occur when some blood constituents on the artery wall get confined away from the wall joining the circulation system.

关键词： oxytactic swimming microorganism swimming variable magnetic field blood clotting endoscopy non-Newtonian fluid

Hydration Characteristics and Immobilization of Cr(Ⅵ) in Slag Cement-CKD Pastes under Hydrothermal Treatment

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Journal of Wuhan University of Technology(materials Science) 2015年第5期30卷 1013-1019页

作者： m R Shatat Gomaa A m Ali m A Tantawy Chemistry Department Faculty of Science Al-Azhar University Faculty of Industrial Science and Technology University Malaysia Pahang (UMP) Chemistry Department Faculty of Science Minia University

The effect of hydrothermal curing regimes on the hydration characteristics of slag cement containing different ratios of cement kiln dust has been studied. The samples for this study were combination of slag cement and cement kiln dust(5%-25%) without and with immobilization of 5% Cr(VI) by mass. Pastes were hydrothermally treated at 180 ℃ for different periods(2-24 h) in well closed stainless steel capsule. The hydration characteristics of these pastes were studied by measuring the compressive strength, bulk density, total porosity and combined water content. The findings were further supported by XRD and SEm analysis. The results indicated that the hydration characteristics of slag cement paste containing cement kiln dust 10% by mass were enhanced, especially at later ages(24 h) of hydration. That is due to the hydrothermal curing regimes of immobilized pastes accelerating hydration reactions and precipitation of Ca Cr O4, indicating that Cr(VI) can be solidified in the cement paste. This precipitation leads to pore formation in hydrated slag cement pastes.

关键词： hydrothermal immobilization slag cement CKD pastes

Bias Effects on the Reynolds Stress Using the multi-Purpose Probe in IR-T1 Tokamak

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Chinese Physics Letters 2016年第1期33卷 88-91页

作者： m.Lafouti m.Ghoranneviss Department of Physics Damavand BranchIslamic Azad University Plasma Physics Research Center Science and Research BranchIslamic Azad University

The effect of the positive bias on Reynolds stress （RS） and its effect on the radial turbulent transport at the edge plasma （r/a =0.9） and scrape-off layer （SOL） region of plasma in tokamak are investigated. The radial and poloidal electric fields （Sr, Ep） and ion saturation current （Is） are measured by multi-purpose probe （mPP）. This probe is fabricated and constructed for the first time in the IR-T1 tokamak. The most advantage of this probe is that the variations of Er and Ep can be measured in different radii at the single shot. Thus the information of different radii can be compared with high precision. The bias voltage is fixed at Vbias = 200 V and it has been applied with the limiter bias that is fixed in r/a = 0.9. moreover, the phase difference between radial and poloidal electric fields, and temporal evolution of the RS .spectrum detected by mPP are calculated. RS magnitude on the edge （r/a = 0.9） is more than its value in the SOL （r/a = 1.02）. With the applied bias 200 V, ItS and the magnitude of the phase difference between Er and Ep are increased, while the radial turbulent transport is decreased simultaneously. Thus it can be concluded that RS affects radial turbulence. Temporal evolution of the RS spectrum shows that the frequency of RS is increased and reaches its highest value at r/a=0.9 in the presence of bias.

关键词： of is RS been in Bias Effects on the Reynolds Stress Using the multi-Purpose Probe in IR-T1 Tokamak on IR

Reducing damage extent of epoxy coating on magnesium substrate by Zr-enhanced PEO coating as an effective pretreatment

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Journal of magnesium and Alloys 2023年第2期11卷 641-656页

作者： Z.Jamshidipour m.Toorani m.Aliofkhazraei m.mahdavian Department of materials Engineering Tarbiat Modares UniversityTehranIran Department of Surface Coatings and Corrosion Institute for Color Science and Technology(ICST)TehranIran

This research was undertaken to study the effect of Zr-enhanced plasma electrolytic oxidation(PEO) as a pretreatment on the corrosion performance of epoxy coating applied on magnesium in 3.5 wt.% Na Cl solution. The parameters of delamination index along with coating damage index were extracted through electrochemical impedance spectroscopy(EIS) tests to determine how Zr may affect the corrosion protection of duplex PEO/epoxy coated samples. Pull-off adhesion tests were also accomplished to form a better understanding of Zr-enhanced PEO coating’ function. According to the obtained results, the presence of Zr can reduce the damage to the coating system by almost twice.

关键词： magnesium EIS Pretreatment PEO Epoxy Zirconyl nitrate