فهرست مطالب

Scientia Iranica - Volume:27 Issue:1, 2019
  • Volume:27 Issue:1, 2019
  • تاریخ انتشار: 1398/09/10
  • تعداد عناوین: 8
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  • R. Gholami *, Reza Ansari Pages 3857-3874
    This paper studies the free vibration charachterstics of post-buckled functionally graded nanocomposite annular plates reinforced by single-walled carbon nanotubes (SWCNTs). The analysis is performed by employing a generalized differenitail quadrature (GDQ)-type numerical technique and psedue arc-length continuation scheme. The SWCNT reinforcement is considered to be either uniformly distributed (UD) or functionally graded (FG) in the thickness direction. The material properties of functionally graded carbon nanotube reinforced composite (FG-CNTRC) plates are estimated using an equivalent continuum model based on the modified rule of mixture. The vibration problem is formulated on the basis of the first-order shear deformation theory for moderately thick laminated plates and von Kármán geometric nonlinearity. By employing Hamilton’s principle and a variational approach, the governing equations and the associated boundary conditions (BCs) are derived which are then discretized via the GDQ method. The postbuckling characteristics of FG-CNTRC annular plates are investigated by plotting the equilibrium postbuckling path as the load-deflection curves. Thereafter, the free vibration behavior of FG-CNTRC annular plates in pre- and post-buckled states is examined. Effects of different parameters including type of BCs, CNT volume fraction, outer radius-to-thickness ratio and inner-to-outer radius ratio are investigated in detail.
    Keywords: Free vibration of postbuckled nanocomposite annular plate, Postbuckling behavior, Carbon nanotube-reinforced composites, Numerical method
  • Shahzada Atif *, Shafqat Hussain, Muhammad Sagheer Pages 3875-3888
    The heat and mass transfer of a magnetohydrodynamic micropolar Carreau nanofluid on a stretching sheet has been analyzed. An internal heating, thermal radiation and viscous dissipation effects are also incorporated. The system of the governing partial differential equations is converted into the ordinary differential equations by invoking the similarity transformation. The resulting ordinary differential equations are then solved by the well known shooting technique. The impact of pertinent physical parameters on the velocity, angular velocity, temperature and concentration profiles are analyzed graphically. The dimensionless velocity is enhanced for the Weissenberg number and the power law index while reverse situation is studied in the thermal and the concentration profile.
    Keywords: magnetohydrodynamics, micropolar Carreau nanofluid, thermal radiation, Joule heating, viscous dissipation
  • Gholamreza Kiani *, Abolfazl Nourizad, Rahimeh Nosrati Pages 3889-3895
    In this paper, leaf-like zinc oxide (ZnO) nanosheets were successfully synthesized by the microwave-assisted method through an easy, low-cost solvothermal process and complied with annealing at 500°C. Characterization of the synthesized material revealed the mesoporous single crystal leaf-like ZnO nanosheets with hexagonal wurtzite structure. Mesoporous and single-crystal structure of gas sensor could provide the high surface area which causes gas molecules to fast diffusing and improve the gas sensitivity. Consequently, the gas-sensing function of the leaf-like ZnO nanosheets was tested for different types of volatile organic compounds (VOC’s). Sensitivity, stability, response and recovery time of leaf-like ZnO nanosheets’ sensor to ethanol vapor was the best at 255°C. According to results, leaf-like ZnO nanosheets is a selective and sensitive sensor for ethanol vapor.
    Keywords: Ethanol sensing, Gas sensor, Leaf-like ZnO, Mesoporous, Nanosheets, microwave
  • Abas Ali Khodadadi, Yadollah Mortazavi, Masoud Vesali Naseh * Pages 3896-3904

    Multi-walled carbon nanotubes (MWCNTs) were functionalized using a dielectric barrier discharge plasma in presence of H2O-saturated air at 70˚C and atmospheric pressure. The functionalized MWCNTs (F-CNTs) were decorated with electrochemically deposited 10 nm NiO nanoparticles, followed by immobilization of glucose oxidase (GOx) and the modified electrode was utilized for electrochemical detection of glucose. TEM, FE-SEM, TPD and XPS techniques were used to characterize the NiO/F-CNTs samples. The maximum amount of oxygenated functional groups such as carbonyl, hydroxyl and carboxylic groups was formed at the plasma exposure time of 4 min. The optimum chronoamperometric deposition time of NiO was 3 min. The presence of GOx on the NiO/F-CNTs electrode displayed a quasi-reversible and surface-controlled redox wave around −0.52 V with a peak to peak separation of 0.05 V. The GOx/NiO/F-CNTs electrode showed a linear performance in the range of 0.2-3.8 mM glucose with detection limit of 93.0 µM and sensitivity of 2.16 µA.mM−1.

    Keywords: Plasma, Functional, carbon nanotubes, Nickel, Biosensor
  • Muhammad Iqbal, Abuzar Ghaffari *, Irfan Mustafa Pages 3905-3916
    A study based on the theoretical investigation of Thermophoresis and Brownian motion effects on radiative heat transfer in the neighborhood of stagnation point. Thermophoresis and Brownian motion play an important role in thermal and mass concentration analyses. These analyses help to comprehend the core ideas to carry out in the discipline of science and technology. An electrically conducting nanofluid is considered which is described by the Buongiorno transport model. The power-law form of the stretching wall velocity allows the similarity solution, the transformed system of the ordinary differential equations is computed numerically with the efficient rapid convergent spectral scheme. The obtained results for velocity, temperature, concentration, shear strain, mass and heat transfer rates are presented graphically for various values of the pertinent parameters. The outcomes divulge that with the increase of power-law exponent, mass and heat transfer rates enhance. The information for the volume and high-temperature transfer rate is provided in the form of Tables. The obtained results are matched with the existing results and are shown to be a good agreement.
    Keywords: Buongiorno nanofluid model, Hiemenz flow, non-linear stretching, spectral method
  • Kashif Ali Abro, Ahmet Yildirim * Pages 3917-3927
    Nanofluids and enhancement of the heat transfer in real systems have proved to be a widely a research area of nanotechnology, specially, improvement in thermal conductivity, thermophoresis phenomenon, dispersion of nanoparticles volume fraction and few others. Based on the touch of nanotechnology, this research article investigates heat transfer of an unsteady flow of micropolar nanofluids on an infinite oscillating plate. Ethylene glycol is considered as a conventional base fluid as well as copper and silver are nanoparticles. Two kinds of nanoparticles (copper and silver) are suspended in ethylene glycol. The governing partial differential equations are fractionalized in terms Caputo-Fabrizio fractional derivative and solved by analytical approach. The general solutions have been established for temperature distribution, microrotation and velocity field by employing integral transforms (Laplace transform) and expressed in terms generalized Fox-H function. The general solutions and their limiting cases rectify the initial and boundary conditions. Finally, the impacts of nanoparticles, Caputo-Fabrizio fractional operator, dimensionless numbers, material parameters and rheological parameters have been underlined by graphical illustrations on flow.
    Keywords: Micropolar nanofluids, Caputo-Fabrizio Fractional Derivative, generalized Fox-H function, Nanoparticles, and Rheological parameters
  • Sumaira Jabeen *, Tasawar Hayat, A Alsaedi, M. Sh. Alhodaly Pages 3928-3937
    Mixed convection flow of tangent hyperbolic liquid over stretching sheet is explored. Joule heating, double stratification, non-linear thermal radiation, Brownian motion and thermophoresis are present. Phenomenon of mass transfer is examined by activation energy along with binary chemical. Computations of convergent solutions are carried out for the nonlinear mathematical system. Graphical representation is employed for outcome of sundry variables on velocity profile, temperature field and concentration of nanoparticles. Moreover, Nusselt number, coefficient of drag force and mass transfer rate are examined. It is observed that velocity decays for larger Weissenberg number. Concentration of fluid enhances for higher activation energy parameter.
    Keywords: Tangent hyperbolic nanofluid, Double stratification, Joule heating, mixed convection, non-linear thermal radiation, Activation energy
  • Masoud Karimipour *, Nafiseh Moradi, Mehdi Molaei, Marzieh Dargahzadeh Pages 3938-3945
    The application of Iron (III) oxide nanoparticles in biology and medicine is much more than the other magnetic nanoparticles. Biocompatibility with human body, stability and ease of production caused the wide range of its development. Single-phase iron (III) oxide nanoparticles were synthesis by use of factory waste soil instead of feedstock with low temperature wet chemical cleaving oxygen method. With respect to the precursor material that is factory waste soil (feedstock), it is cost-effective economically and also is innovative. In this synthesis method, single-phase iron(III) oxide were obtained by acid digestion of waste soil. The nanoparticles were analyzed by: Fourier Transform Infrared spectroscopy (FTIR), X-Ray Diffraction (XRD) that the crystallite size of nanoparticles calculated by XRD peaks and Debye-Scherrer formula and obtained 11 nm. Transmission Electron Microscope (TEM) images showed the spherical shape of nanoparticles with average size of 10 nm. Vibrating sample magnetometery (VSM) analysis was applied to determine the magnetic saturation and the size of nanoparticles was estimated 9 nm from this analysis. Fourier Transform Infrared spectroscopy gently shows the atomic bond between iron and oxygen (Fe-O) in nanoparticles. The results of X-ray Diffraction show that the sample was synthesized are cubic Spinel single-phase.
    Keywords: Superparamagnetic nanoparticles, Cleaving oxygen method, Iron (III) oxide, soil