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Transient flow of magnetized Maxwell nanofluid: Buongiorno model perspective of Cattaneo-Christov theory

Applied Mathematics and Mechanics(English Edition) 2020年第4期41卷 655-666页

作者： M.KHAN A.ahmed J.ahmed Department of Mathematics Quaid-i-Azam UniversityIslamabad 44000Pakistan Department of Basic Sciences University of Engineering and TechnologyTaxila 47050Pakistan

The present research article is devoted to studying the characteristics of Cattaneo-Christov heat and mass fluxes in the Maxwell nanofluid flow caused by a stretching sheet with the magnetic field *** Maxwell nanofluid is investigated with the impact of the Lorentz force to examine the consequence of a magnetic field on the flow characteristics and the transport of *** heat and mass transport mechanisms in the current physical model are analyzed with the modified versions of Fourier’s and Fick’s laws,***,the well-known Buongiorno model for the nanofluids is first introduced together with the Cattaneo-Christov heat and mass fluxes during the transient motion of the Maxwell *** governing partial differential equations(PDEs)for the flow and energy transport phenomena are obtained by using the Maxwell model and the Cattaneo-Christov theory in addition to the laws of *** transformations are used to convert the PDEs into a system of nonlinear ordinary differential equations(ODEs).The homotopic solution methodology is applied to the nonlinear differential system for an analytic *** results for the time relaxation parameter in the flow,thermal energy,and mass transport equations are discussed *** is noted that higher values of the thermal and solutal relaxation time parameters in the Cattaneo-Christov heat and mass fluxes decline the thermal and concentration fields of the ***,larger values of the thermophoretic force enhance the heat and mass transport in the ***,the Brownian motion of the nanoparticles declines the concentration field and increases the temperature *** validation of the results is assured with the help of numerical tabular data for the surface velocity gradient.

关键词： transient flow Cattaneo-Christov theory Maxwell nanofluid Buongiorno model homotopy analysis method (HAM) solution

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Thermal analysis in swirl motion of Maxwell nanofluid over a rotating circular cylinder

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Applied Mathematics and Mechanics(English Edition) 2020年第9期41卷 1417-1430页

作者： A.ahmed M.KHAN J.ahmed Department of Mathematics Quaid-i-Azam UniversityIslamabad 44000Pakistan Department of Basic Sciences University of Engineering and TechnologyTaxila 47050Pakistan

In this paper,the mechanism of thermal energy transport in swirling flow of the Maxwell nanofluid induced by a stretchable rotating cylinder is *** rotation of the cylinder is kept constant in order to avoid the induced axially secondary ***,the novel features of heat generation/absorption,thermal radiation,and Joule heating are studied to control the rate of heat *** effects of Brownian and thermophoretic forces exerted by the Maxwell nanofluid to the transport of thermal energy are investigated by utilizing an effective model for the nanofluid proposed by *** whole physical problem of fluid flow and thermal energy transport is modelled in the form of partial differential equations(PDEs)and transformed into nonlinear ordinary differential equations(ODEs)with the help of the suitable flow *** acquired results through the technique bvp4c are reported graphically with physical *** analysis reveals that there is higher transport of heat energy in the Maxwell nanoliquid for a constant wall temperature(CWT)as compared with the prescribed surface temperature(PST).Both thermophoretic and Brownian forces enhance the thermal energy transport in the flowing Maxwell ***,the temperature distribution increases with increasing values of the radiation parameter and the Eckert *** is also noted that an increase in Reynolds number reduces the penetration depth,and as a result the flow and transport of energy occur only near the surface of the cylinder.

关键词： Maxwell nanofluid rotating cylinder heat source/sink Joule heating convective condition numerical solution

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Aharonov-Bohm effect for bound states on spin-0 massive charged particles in a Gödel-type space-time with Coulomb potential

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Communications in Theoretical Physics 2020年第7期72卷 36-41页

作者： Faizuddin ahmed Ajmal College of Arts and Science Dhubri-783324AssamIndia

In this paper,we investigate the relativistic quantum dynamics of spin-0 massive charged particles in a G?del-type space-time with electromagnetic *** derive the radial wave equation of the Klein-Gordon equation with an internal magnetic flux field and Coulombtype potential in the Som-Raychaudhuri space-time with cosmic *** solve this equation and analyze the analog effect in relation to the Aharonov-Bohm effect for bound states.

关键词： Göodel-type metrics relativistic wave equations bound states electromagnetic potential energy spectrum wave-functions

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SOME PROPERTIES OF m-ISOMETRIES AND m-INVERTIBLE OPERATORS ON BANACH SPACES

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Acta Mathematica Scientia 2012年第2期32卷 520-530页

作者： Ould ahmed Mahmoud Sid ahmed Department of Mathematics College of ScienceAljouf UniversityAljouf 2014Saudi Arabia

This article has two purposes： the first is to give some structure results for the class of m-isometries, and the second purpose is to extend the notions of left and right inverses to m-left and m-right inverses resp... 详细信息

关键词： m-isometry m-left inverse m-right inverse approximate spectrum pointspectrum

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Dry face milling of titanium alloys

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Journal of University of Science and Technology Beijing 2004年第6期11卷 545-548页

作者： ahmed Hassan Manufacturing and Automation Department

In machining titanium alloys, cutting tools generally wear out very rapidlybecause of the high cutting temperature resulted from the low thermal conductivity and density ofthe work material. In order to increase the tool life, it is necessary to suppress the cutting heatas much as possible by applying an abundant amount of coolant, but this will entail serioustechno-environmental and biological problems. To study the performance and avoid these limitations,a PVD-coated insert was used to the dry face mill of (alpha + beta) titanium alloys. As a result itwas found that the inserts exhibit an excellent cutting performance at low cutting speeds and feedrates, and there is no significant difference in the dominant insert failure mode between the wetand dry cutting in discontinuous cutting.

关键词： carbide tool face milling titanium alloy

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Numerical investigation of tunneling induced surface movement:A case study of MRT line 1,Dhaka

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Underground Space 2023年第5期12卷 116-136页

作者： Khondaker Sakil ahmed Johana Sharmin Mehedi ahmed Ansary Department of Civil Engineering Military Institute of Science and TechnologyDhaka 1216 Bangladesh Department of Civil Engineering Bangladesh University of Engineering and TechnologyDhaka 1216Bangladesh

The proposed underground tunnel for Mass Rapid Transit Line 1,Dhaka brings immense attention to the engineers and experts not only because of its construction challenges through a densely-built city,but also for the potential tunneling-induced ground *** very preliminary study investigates the ground surface movement due to the progression of the tunnel boring machine(TBM)using numerical analysis.A series of finite element(FE)models have been developed using PLAXIS 3D,in which Mohr–Coulomb(MC),modified Cam-Clay(MCC),and hardening soil(HS)have been *** in-field data of Mashhad Metro Line-2 have been compared to verify PLAXIS 3D’s efficacy in tunnel ***,the outcomes of the FE analyses are compared with the existing empirical *** PLAXIS 3D analysis considering the MCC soil model exhibits strong agreement with the real monitored data,with a variance of only 3.85%.After simulating different stages of the tunnel construction,results are reported in terms of the distance of the inflexion point from the center,the settlement trough pattern,the maximum transverse settlements,and the vertical *** are also compared with the established empirical *** order to comprehend the surface settlement with various tunnel depths and diameters,a parameter dependency study has been carried *** analysis findings showed that increasing the TBM’s depth and radius causes the inflexion point’s distance from the center of the tunnel to increase by 4%and decrease by 5%,*** is also observed that as tunnel depth increases,the overall settlement of the tunnel lowers by 11%for every additional 5 meters of *** MCC model,out of the three,exhibits the most accurate value of the settlement compared to that obtained from the empirical solutions,and also the best-fit form to the Gaussian curve.

关键词： Surface settlement TBM Finite element analysis MC model MCC model

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A Comparative Study on the Corrosion Performance of Ni_(47)Ti_(49)Co_4 and Ni_(51)Ti_(49) Shape Memory Alloys in Simulated Saliva Solution for Dental Applications

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Acta Metallurgica Sinica(English Letters) 2016年第11期29卷 1001-1010页

作者： Rasha A.ahmed Chemistry Department Faculty of Science Taif University Forensic Chemistry Laboratories Medico Legal DepartmentMinistry of Justice

In this study, the corrosion behavior of Ni47Ti49Co4 shape memory alloy（SMA） was investigated in simulated saliva solution with the binary alloy Ni（51）Ti49 as a reference. The surface morphology and the chemical composition of the oxide films were characterized by scanning electron microscopy and X-ray photoelectron spectroscopy before and after immersion in the test solutions, respectively. The results showed that the ternary alloy was less affected by the test solution,owning to the formation of passive layer composed mainly of the oxides of titanium and cobalt in several oxidation *** voltammetry, electrochemical impedance spectroscopy and potentiodynamic polarization measurements affirmed that the passive oxide film significantly improved the corrosion resistance of Ni47Ti49Co4 SMAs as demonstrated by the smaller corrosion current density, larger resistance and smaller capacitance. Consequently, alloying with cobalt, which has paramount importance in enhancing the passive layer, expands the use of Ni47Ti49Co4 SMAs in dental work as new nitinol alloys with high corrosion resistances.

关键词： Ni47Ti49Co4 Shape memory alloy (SMA) Corrosion Artificial saliva X-ray photoelectronspectroscopy (XPS)

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Influence of temperature on the properties of one-dimensional piezoelectric phononic crystals

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Chinese Physics B 2018年第9期27卷 342-345页

作者： ahmed Nagaty ahmed Mehaney Arafa H Aly Physics Department Faculty of Sciences Beni-Suef University

The current study investigates the influence of temperature on a one-dimensional piezoelectric phononic crystal using tunable resonant frequencies. Analytical and numerical examples are introduced to emphasize the influence of temperature on the piezoelectric phononic crystals. It was observed that the transmission spectrum of a one-dimensional phononic crystal containing a piezoelectric material（0.7 PMN-0.3 PT） can be changed drastically by an increase in *** resonant peak can be shifted toward high or low frequencies by an increase or decrease in temperature, ***, we deduced that temperature can exhibit a large tuning in the phononic band gaps and in the local resonant frequencies depending on the presence of a piezoelectric material. Such result can enhance the harvesting energy from piezoelectric materials, especially those that are confined in a phononic crystal.

关键词： phononic crystals resonant modes piezoelectric material thermal properties and temperature

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A Type D Non-Vacuum Spacetime with Causality Violating Curves, and Its Physical Interpretation

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Communications in Theoretical Physics 2017年第12期67卷 735-740页

作者： Faizuddin ahmed Ajmal College of Arts and Science

We present a topologically trivial, non-vacuum solution of the Einstein's field equations in four dimensions,which is regular everywhere. The metric admits circular closed timelike curves, which appear beyond the null curve, and these timelike curves are linearly stable under linear perturbations. Additionally, the spacetime admits null geodesics curve, which are not closed, and the metric is of type D in the Petrov classification scheme. The stress-energy tensor anisotropic fluid satisfy the different energy conditions and a generalization of Equation-of-State parameter of perfect fluid p = ωρ. The metric admits a twisting, shearfree, nonexapnding timelike geodesic congruence. Finally, the physical interpretation of this solution, based on the study of the equation of the geodesics deviation, will be presented.

关键词： exact solution anisotropic fluid closed timelike curves wave propagation and interactions

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Carbon nanotube-based nanoelectromechanical resonatoras mass biosensor

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Chinese Physics B 2020年第7期29卷 583-587页

作者： ahmed MElseddawy Adel HPhillips ahmed S Bayoumi Faculty of Graduate Studies University of WindsorWindsorOntarioCanada Faculty of Engineering Ain-Shams UniversityCairoEgypt Faculty of Engineering Kafr-Elsheikh UnversityKafr-ElsheikhEgypt

The use of single walled carbon nanotube-based nanoelectromechanical system(NEMS)resonator to sense the biomolecules'mass is investigated under the influence of an external ac-field.A single walled carbon nanotube(SWCNT)cantilever has been proposed and studied if the mass is attached at the tip or various intermediate *** shift of the resonant frequency and the quality factor have been investigated and show high sensitivity to the attached mass of biomolecule and its *** proposed SWCNT-based NEMS resonator is a good candidate for sensing and tracing biomolecules'mass as concentration of acetone in human exhale,resulting in a painless,correct,and simple diabetics'diagnosis.

关键词： single walled carbon nanotube nanoelectromechanical system resonator ac-field biomolecule

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