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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

Electrical Conductivity and Sensitive Characteristics of Ag-Added BaTiO_3-CuO mixed Oxide for CO_2 Gas Sensing

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Journal of materials Science & Technology 2011年第1期27卷 35-40页

作者： A.m.El-Sayed F.m.Ismail S.m.Yakout Inorganic Chemistry Department National Research CentreTahrir StreetDokki P.C.12622 CairoEgypt

Carbon dioxide gas sensors based on BaTiO3-CuO composite with different concentrations of Ag addition（1,1.5 and 2 wt%） have been prepared by stander ceramic method and sintered at 500 and 700℃ for 5 *** conductivity and gas sensing properties of the prepared samples were *** conductivity measurement was used to characterize the obtained sintered sensor *** was found that electrical conductivity and the sensitivity to CO2 were improved with Ag addition and *** correlation between Ag content at different sintering temperature and sensing characteristics towards CO2 is discussed.

关键词： BaTiO3-CuO composite Ag addition Electrical conductivity CO2 sensitive properties

Small dissymmetry, yet large effects on the transport propertiesof electrolytes based on imide salts: Consequences on performancein Li-ion batteries

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Journal of Energy Chemistry 2022年第2期31卷 352-366页

作者： Joseph Chidiac Laure Timperman mérièm Anouti Laboratoire PCm2E Universitéde ToursParc de Grandmont37200 ToursFrance

To gain better insight into the influence of the anion size and symmetry on the transport properties and thermal stability of an electrolyte based on lithium(fluorosulfonyl)(trifluoromethanesulfonyl)-imide(FTFSI)salt,we performed the physical and electrochemical characterization of an electrolyte based on FTFSI incorporated in standard binary(3 EC/7 EmC)and ternary(EC/PC/3 DmC)alkylcarbonate *** applying the Jones-Dole-Kaminsky(JDK),Eyring and Arrhenius empirical models to the electrolyte viscosity we show that the activation enthalpy and entropy energy barriers(ΔH≠,ΔS≠)for viscous flow are between 12 and 15 kJ·mol^(-1).They are strongly dependent on the solvent nature and are significantly lower than their symmetric anions LiFSI and LiTFSI(19-20 kJ·mol^(-1))in the binary ***,the hydrodynamic radius,rs,calculated by JDK,and the ionicity behavior illustrated by the Walden role,showed that the FTFSI anion is outside the solvation sphere(rs>0.6 nm)which is smaller in the case of an EC/EmC solvent *** the 3 EC/7 EmC solvent mixture,LiFTFSI is less conductive than in the ternary mixture i.e.,σ_(max)=8.9 mS cm^(-1) at C_(max)=1.1 mol L^(-1) for 3 EC/7 EmC and,σ_(max)=10.5 mS cm^(-1) at max=0.7 mol L^(-1) for EC/PC/3 DmC,due to a strong solvation and a greater association of FTFSI ions in the binary solvent *** thermal stability of FTFSI based electrolytes was determined by the shift of the evaporation temperature of the volatile solvents(DmC,EmC)in the presence of salt,towards the higher *** feature is visible on the thermograms obtained by DSC both with the liquid electrolyte and with charged LmO cathodes in presence of *** consequences of these properties on the electrochemical behavior of a graphite(Gr)half-cell,a lithium metal(Li)anode and a manganese lithium oxide(LmO)cathode demonstrated on the one hand the formation of a thick solid electrolyte interphase(SEI)on graphite that consumed a significant amou

关键词： LiFTFSI Electrolyte Viscosity Interface Li-ion battery