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Applied mathematics and mechanics(English Edition) 2024年第2期45卷 373-388页

作者： m.rahman m.TURKYILmAZOGLU Z.mUSHTAQ Department of mathematics Mirpur University of Science and TechnologyMirpur 10250Pakistan Department of mathematics Hacettepe UniversityBeytepeAnkara 06532Turkiye

In this study,we examine the effects of various shapes of nanoparticles in a steady flow of hybrid nanofluids between two stretchable rotating *** steady flow of hybrid nanofluids with transformer oil as the base fluid and Fe_(3)O_(4)+TiO_(2)as the hybrid nanofluid is *** shapes of Fe_(3)O_(4)+TiO_(2)hybrid nanofluids,including sphere,brick,blade,cylinder,and platelet,are *** shape exists in the same volume of a *** leading equations(partial differential equations(PDEs))are transformed to the nonlinear ordinary differential equations(ODEs)with the help of similarity *** system of equations takes the form of ODEs depending on the boundary conditions,whose solutions are computed numerically by the bvp4c mATLAB *** outputs are compared with the previous findings,and an intriguing pattern is discovered,such that the tangential velocity is increased for the rotation parameter,while it is decreased by the stretching values because of the lower *** the reaction rate parameter,the concentration boundary layer becomes shorter,and the activation energy component increases the rate at which mass transfers come to the higher disk but have the opposite effect on the bottom *** ranges of various parameters taken into account are Pr=6.2,Re=2,m=1.0,φ_(1)=φ_(2)=0.03,K=0.5,S=-0.1,Br=0.3,Sc=2.0,α_(1)=0.2,γ=0.1,E_(n)=2.0,and q=1.0,and the rotation factor K is within the range of 0 to 1.

关键词： transformer oil Brinkman number skin friction coefficient double rotating disk Nusselt number Sherwood number

Effects of surface finish and treatment on the fatigue behaviour of vibrating cylinder block using frequency response approach

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第3期7卷 352-360页

作者： rahman m. m. ARIFFIN A. K. Computational and Experimental mechanics Group Department of Mechanical and Materials Engineering Universiti Kebangsaan Malaysia 43600 UKM Bangi Selangor DE Malaysia

This paper presents the effects of surface finish and treatment on the high cycle fatigue behaviour of vibrating cylinder block of a new two-stroke free piston engine at complex variable amplitude loading conditions using frequency response approach. Finite element modelling and frequency response analysis was conducted using finite element analysis software Package ***/*** and fatigue life prediction was carded out using *** software. Based on the finite element results, different frequency response approach was applied to predict the cylinder block fatigue life. Results for different load histories and material combinations are also discussed. Results indicated great effects for all surface finish and treatment. It is concluded that polished and cast surface finish conditions give the highest and lowest cylinder block lives, respectively; and that Nitrided treatment leads to longest cylinder block life. The results were used to draw contour plots of fatigue life and damage in the worst or most damaging case.

关键词： Finite element method Fatigue life Surface finish Surface treatment Frequency response approach

Impacts of Heat Flux Distribution, Sloping magnetic Field and magnetic Nanoparticles on the Natural Convective Flow Contained in a Square Cavity

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Fluid Dynamics & materials Processing 2020年第3期16卷 441-463页

作者： Latifa m.Al-Balushi m.m.rahman Department of mathematics College of ScienceSultan Qaboos UniversityMuscatOman

In the present paper,the effect of the heat flux distribution on the natural convective flow inside a square cavity in the presence of a sloping magnetic field and magnetic nanoparticles is explored *** nondimensional governing equations are solved in the framework of a finite element method implemented using the Galerkin *** role played by numerous model parameters in influencing the emerging thermal and concentration fields is examined;among them are:the location of the heat source and its lengthH,the magnitude of the thermal Rayleigh number,the nanoparticles shape and volume fraction,and the Hartmann *** is found that the nanofluid velocity becomes higher when the thermal source length,the nanoparticles volume fraction and/or the thermal Rayleigh number are increased,while it decreases as the Hartmann number Ha grows and the position of the heat source moves toward the center of the lower wall of the ***,the temperature of the nanofluid grows with the extension of the thermal source and decreases slowly when the heat flux position moves toward the center of the lower *** outcomes of the research also indicate that the average Nusselt number becomes smaller on increasing Hartmann number Ha and heat source length H^(*).The addition of Fe_(3)O_(4) to engine oil leads to a higher rate of heat transfer with respect to the addition of SiO_(2) ***-shaped nanoparticles generate the highest value of the Nusselt number compared to all the other considered shapes.

关键词： Nanofluids magnetic nanoparticles heat source natural convection finite element method square enclosure

Cylindrical and Spherical Electron-Acoustic Shock Waves in Electron-Positron-Ion Plasmas with Nonextensive Electrons and Positrons

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Communications in Theoretical Physics 2015年第2期63卷 243-248页

作者： A.Rafat m.m.rahman m.S.Alam A.A.mamun Department of Physics Jahangirnagar University

Electron-acoustic shock waves （EASWs） in an unmagnetized four-component plasma （containing hot elec- trons and positrons following the q-nonextensiv.e distribution, cold mobile viscous electron fluid, and immobile positive ions） are studied in nonplanar （cylindrical and spherical） geometry. With the help of the reductive perturbation method, the modified Burgers equation is derived. Analytically, the effects of nonplanar geometry, nonextensivity, relative number density and temperature ratios, and cold electron kinematic viscosity on the basic properties （viz. amplitude, width, speed, etc.） of EASWs are discussed. It is exarmined that the EASWs in nonplanar geometry significantly differ from those in planar geometry. The results of this investigation can be helpful in understanding the nonlinear features of EASWs in various astrophysical plasmas.

关键词： electron-acoustic shock waves electron-positron-ion plasmas modified Burgers equation nonpla-nar geometry nonextensivity

Bilirubin sensor based on CuO-CdO composites deposited in a nafion/glassy carbon electrode matrixes

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Progress in Natural Science:materials International 2017年第5期27卷 566-573页

作者： mohammed m.rahman mohammad musarraf Hussain Abdullah m.Asiri Chemistry Department King Abdulaziz UniversityFaculty of Science Center of Excellence for Advanced material Research (CEAmR) King Abdulaziz University

Copper oxide-cadmium oxide nanocomposites(CuO-CdO NCs) were synthesized by solvothermal technique in a basic medium. CuO-CdO NCs were characterized using conventional techniques, such as Fourier Transform Infrared Spectroscopy(FTIR), UV–Visible Spectroscopy(UV/Vis), Field-Emission Scanning Electron microscopy(FESEm), X-ray electron dispersive spectroscopy(XEDS), X-ray photoelectron spectroscopy(XPS), and powder X-ray diffraction(XRD). A selective and enzyme-less Bilirubin(BLR) sensor was developed with a thin-layer of NCs onto a glassy carbon electrode(GCE, surface area = 0.0316 cm~2) using 5% nafion binders at room conditions. Improved electrochemical performances of higher sensitivity, lower detection limit,linear dynamic range(LDR), and long-term stability of preferred BLR were achieved by a reliable currentvoltage(I-V) approach. The calibration curve was found linear(R~2= 0.9347) in a wide range of BLR concentration(10.0 pm ~ 10.0 mm). Based on the signal to noise ratio value of 3, the sensitivity and limit of detection(LOD) of the sensor were calculated as 95.0 pA μm-1cm-2and 1.0 ± 0.1 pm *** synthesized CuO-CdO NCs/GCE is an excellent advancement of developing a selective and sensitive BLR sensor by electrochemical approach and practically implemented in real sample applications.

关键词： CuO-CdO nanocomposites Bilirubin biosensor Glassy carbon electrode Sensitivity Real sample analysis Health care field

Roles of Superthermal Electrons and Adiabatic Heavy Ions on Heavy-Ion-Acoustic Solitary and Shock Waves in a multi-Component Plasma

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Communications in Theoretical Physics 2015年第8期64卷 208-214页

作者： m.G.Shah m.m.rahman m.R.Hossen A.A.mamun Department of Physics Jahangirnagar University Department of Natural Sciences Daffodil International University

Heavy-ion-acoustic(HIA) waves in an unmagnetized collisionless plasma system comprising superthermal electrons, Boltzmann distributed light ions, and adiabatic positively charged inertial heavy ions have been investigated both numerically and analytically. The well-known reductive perturbation method has been used to derive the Kortewegde Vries(K-d V) and Burgers(BG) equations. The parametric regimes for the existence of both the positive and negative solitary and shock waves have been obtained. The effects of adiabaticity of heavy ions and superthermality of electrons,which are found to notably modify the fundamental features(viz. polarity, amplitude, phase speed, etc.) of HIA solitary and shock waves, are precisely studied. The results of our theoretical investigation can be applicable to understand the characteristics and basic nonlinear structures of HIA waves both in space and laboratory plasma situations.

关键词： heavy-ion acoustic waves superthermality adiabatic

Electrochemically Assisted Photocatalytic Oxidation of methanol on TiO_2 Nanotube Arrays

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Journal of materials Science & Technology 2010年第6期26卷 535-541页

作者： R.mohammadpour A.Iraji zad N.Taghavinia m.rahman m.m.Ahadian Institute for Nanoscience and Nanotechnology Sharif University of Technology Department of Physics Sharif University of Technology

The influence of an externally applied bias on photocatalytic performance of crystallized TiO2/Ti nanotubular electrode formed by anodization in fluoride-based electrolyte were investigated and compared to the behavior of multiporous TiO2 electrode. The photoelectrocatalytic oxidation behavior of methanol over the nanotubular electrode has been studied by measuring photocurrent response, potentiodynamic polarization spectroscopy and using electrochemical impedance spectroscopy （EIS）. It was found that the photoelectrocatalytic oxida- tion and the charge transfer rate constant of reaction on TiO2/Ti nanotubular electrode can significantly be increased by applying electrochemical bias. moreover, TiO2 electrodes have considerably better performance alytic performance. based on the results, it was found that the nanotubular in comparison with porous samples in photoelectrocatalytic performance.

关键词： TiO2 nanotube Photoelectrocatalyst Electrochemical impedance spectroscopy methanol

Role of ZnO-CeO_2 Nanostructures as a Photo-catalyst and Chemi-sensor

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Journal of materials Science & Technology 2011年第7期27卷 594-600页

作者： m. Faisal Sher Bahadar Khan mohammed m. rahman Aslam Jamal Kalsoom Akhtar m.m. Abdullah Centre for Advanced materials and Nano-Engineering (CAmNE) and Department of Chemistry Faculty of Sciences and Arts Najran UniversityNajran 11001 Kingdom of Saudi Arabia Division of Nano Sciences and Department of Chemistry Ewha Womans UniversitySeoul 120-750 Korea

ZnO-CeO2 nanostructures were synthesized by simple and effcient low temperature method. The structure and morphology of the ZnO-CeO2 nanostructures were characterized by X-ray powder diffraction （XRD） and field emission scanning electron microscopy （FESEm）, which revealed elongated shaped CeO2 nanoparticles with diameters of 40–90 nm distributed on the surface of elongated ZnO nanostructures with diameters of 50–200 nm （edge–centre）. Further the structure of the synthesized ZnO-CeO2 nanostructure was supported by Raman spectra and Fourier transform infrared spectroscopy （FTIR）. UV-vis absorption spectrum was used to confirm the optical properties of the CeO2 doped ZnO nanostructures. Photo-catalytic activity of CeO2 doped ZnO nanostructure was evaluated by degradation of acridine orange and methylene blue which degraded 84.55% and 48.65% in 170 min, respectively. ZnO-CeO2 nanostructures also showed good sensitivity （0.8331 μA·cm-2·（mol/l）-1） in short response time （10 s） by applying to chemical sensing using ethanol as a target compound by I-V technique. These degradation and chemical sensing properties of ZnO-CeO2 nanostructures are of great importance for the application of ZnO-CeO2 system as a photo-catalyst and chemical sensor.

关键词： ZnO-CeO2 nanostructures Structural properties Optical properties Photocatalytic activity Ethanol sensing

Numerical Simulations of Hydromagnetic mixed Convection Flow of Nanofluids inside a Triangular Cavity on the Basis of a Two-Component Nonhomogeneous mathematical model

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Fluid Dynamics & materials Processing 2021年第1期17卷 1-20页

作者： Khadija A.Al-Hassani m.S.Alam m.m.rahman Department of mathematics College of ScienceSultan Qaboos UniversityMuscatOman Department of mathematics Jagannath UniversityDhakaBangladesh

Nanofluids have enjoyed a widespread use in many technological applications due to their peculiar *** simulations are presented about the unsteady behavior of mixed convection of Fe_(3)O_(4)-water,Fe_(3)O_(4)-kerosene,Fe_(3)O_(4)-ethylene glycol,and Fe_(3)O_(4)-engine oil nanofluids inside a lid-driven triangular *** particular,a two-component non-homogeneous nanofluid model is *** bottom wall of the enclosure is insulated,whereas the inclined wall is kept a constant(cold)temperature and various temperature laws are assumed for the vertical wall,namely:θ=1(Case 1),θ=Yð1YÞ(Case 2),andθ=sinð2-YÞ(Case 3).A tilted magnetic field of uniform strength is also present in the fluid *** a numerical point of view,the problem is addressed using the Galerkin weighted residual finite element *** role played by different parameters is assessed,discussed critically and interpreted from a physical *** find that a higher aspect ratio can produce an increase in the average Nusselt ***,the Fe_(3)O_(4)-EO and Fe_(3)O_(4)-H2O nanofluids provide the highest and smallest rate of heat transfer,respectively,for all the considered(three variants of)thermal boundary conditions.

关键词： Nanofluid mixed convection lid-driven triangular cavity finite element method

Natural convective heat transfer in a square enclosure utilizing magnetic nanoparticles

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Propulsion and Power Research 2019年第3期8卷 194-209页

作者： Latifa m.Al-Balushi m.J.Uddin m.m.rahman Department of mathematics College of ScienceSultan Qaboos UniversityP.O.Box 36Al-KhodP.C.123MuscatSultanate of Oman Department of General Educational Development Daffodil International University102 ShukrabadDhanmondiDhaka 1207Bangladesh

In the present paper,unsteady natural convective heat transfer flow inside a square enclosure filled with nanofluids containing magnetic nanoparticles using nonhomogeneous dynamic model is investigated *** horizontal top wall of the enclosure is considered a colder wall and the bottom wall is maintained at uniform temperature whereas two other vertical walls of the cavity are thermally *** Galerkin weighted residual finite element method has been used to solve the governing non-dimensional partial differential *** numerical simulations,four types of nanoparticles such as magnetite(Fe_(3)O_(4)),cobalt ferrite(CoFe_(2)O_(4)),mn-Zn ferrite(mn-ZnFe_(2)O_(4)),and silicon dioxide(SiO2),and three types of base fluids such as water(H_(2)O),engine oil(EO)and kerosene(Ke)have been *** with previously published work are performed and excellent agreement is *** effects of various model parameters such as thermal Rayleigh number,nanoparticles volume fraction and nanoparticles shape factor are *** results show that the average Nusselt number increases as the thermal Rayleigh number and nanoparticles volume fraction *** results indicate that the average Nusselt numbers are higher for the blade shape of nanoparticles.

关键词： Nanofluids Nanoparticles Heat transfer Natural convection Square enclosure Finite element method