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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

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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

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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

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

Deposition behavior and tribological properties of diamond-like carbon coatings on stainless steels via chemical vapor deposition

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International Journal of minerals,metallurgy and materials 2018年第11期25卷 1335-1343页

作者： Labani mustafi m.m.rahman mohammad Nur E Alam Al Nasim mohammad Asaduzzaman Chowdhury m.H.monir School of materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China School of Engineering RMIT UniversityMelbourneVictoria 3001Australia Dhaka University of Engineering and Technology Gazipur 1707Bangladesh

A systematic investigation was carried out to observe the deposition rate of a diamond-like carbon(DLC) coating on two stainless steel substrates by chemical vapor deposition(CVD). The objective of this research is to study the deposition behavior of the DLC coating and its tribological properties in different combinations of methane(CH_4) and nitrogen, which were used as precursor gases. The results reveal that the deposition rate increases with increasing CH_4 content up to 50 vol%. The hardness of the DLC-deposited layer also increases while the friction coefficient decreases with increasing CH_4 gas content up to 50% in the precursor gas mixture.

关键词： diamond-like carbon chemical vapor deposition methane and nitrogen gas mixtures deposition rate hardness friction coefficient

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Statistical model for Impact and Energy Absorption of 3D Printed Coconut Wood-PLA

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Energy Engineering 2021年第5期118卷 1305-1315页

作者： J.Kananathan m.Samykano K.Kadirgama D.Ramasamy m.m.rahman Green Kingdom Solutions Sdn.Bhd. Taman Salak SelatanKuala Lumpur57100Malaysia College of Engineering Universiti Malaysia PahangGambangPahang26300Malaysia Faculty of mechanical&Automotive Engineering Technology Universiti Malaysia PahangPekanPahang26600Malaysia

Fused deposition modeling(FDm)-3D printing has been the favored technology to build functional components in various *** present study investigates infill percentage and infill pattern effects on the printed parts’impact properties through the 3D printing technique using coconut wood-filled PLA *** models are also proposed in the present study with the aim for future property *** to the ASTm standard,fifteen specimens with different parameter combinations were printed using a low-cost FDm 3D printer to evaluate their impact *** analysis was performed using mINITAB to validate the experimental data and model *** experimental outcomes reveal the honeycomb pattern with 75%infill density achieves the highest energy absorption(0.837 J)and impact energy(5.1894 kJ/m^(2)).The p-value from statistical analysis clearly shows that all the impact properties are less than the alpha value of 0.05,suggesting all the properties are vital to determine the impact *** validation process affirms that the generated mathematical model for the energy absorbed and the impact energy is reliable at an acceptable level to predict their respective *** errors between the experimental value and the predicted value are 3.98%for the energy absorbed and 4.06%for impact *** findings are expected to provide insights on the impact behavior of the coconut wood-filled PLA composites prepared by FDm-3D printing and a mathematical model to predict the impact properties.

关键词： Impact energy energy absorption response surface methodology coconut wood ANOVA

APPLICABILITY OF THE BEND DEVELOPmENT THEORY IN NATURAL ALLUVIAL RIVERS

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International Journal of Sediment Research 2002年第3期17卷 211-219页

作者： m.m.rahman m.A.HAQUE m.m.HOQUE Assistant Professor Associate Professor Bangladesh Bangladesh University of Engineering and Technology(BUET) Dhaka-1000 Institute of WAter and Flood management(IWFm) the same as above.

The theoretical conditions for the bend development or attenuation have been reviewed and tested for a study reach of the meghna river. The field observations in the natural alluvial meander do not support the theories developed for bend development. The limitations of the theory to apply in the natural meandering river are discussed.

关键词： Theoretical conditions Bend development or attenuation The meghna River Natural meandering river

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新加坡的银行监管机制

经营与管理 2004年第9期 51-53页

作者：吴海兵 m.m.rahman 孟加拉福建厦门

我国银行监管如何有效发挥监管效能,防范金融风险,提高银行业的国际竞争力,是当前我国银行监管当局的首要课题。新加坡在金融自由化的过程中,金融管理局(mAS)形成了一套高效的银行监管制度。在我国银行业加速开放的今天,研究新加坡的银... 详细信息

我国银行监管如何有效发挥监管效能,防范金融风险,提高银行业的国际竞争力,是当前我国银行监管当局的首要课题。新加坡在金融自由化的过程中,金融管理局(mAS)形成了一套高效的银行监管制度。在我国银行业加速开放的今天,研究新加坡的银行监管经验无疑可为我国目前的银行监管体制改革提供一些借鉴和参考。

关键词：新加坡银行监管机制金融风险金融自由化 mAS 金融管理局风险分析

Development of IDF Curve for Dhaka City Based on Scaling Theory under Future Precipitation Variability Due to Climate Change

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Development of IDF Curve for Dhaka City Based on Scaling The...