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    On the existence of chaotic circumferential waves in spinning disks

    , Article Chaos ; Volume 17, Issue 2 , 2007 ; 10541500 (ISSN) Angoshtari, A ; Jalali, M. A ; Sharif University of Technology
    American Institute of Physics Inc  2007
    Abstract
    We use a third-order perturbation theory and Melnikov's method to prove the existence of chaos in spinning circular disks subject to a lateral point load. We show that the emergence of transverse homoclinic and heteroclinic points lead, respectively, to a random reversal in the traveling direction of circumferential waves and a random phase shift of magnitude π for both forward and backward wave components. These long-term phenomena occur in imperfect low-speed disks sufficiently far from fundamental resonances. © 2007 American Institute of Physics  

    Effects of geometric factors and material properties on stress behavior in rotating disk

    , Article Indian Journal of Science and Technology ; Vol. 7, issue. 1 , Jan , 2014 , p. 1-6 Monfared, V ; Hassan, M ; Daneshmand, S ; Taheran, F ; Ghaffarivardavagh, R ; Sharif University of Technology
    Abstract
    In this study, effects of geometric factors and material properties are investigated on stress behavior of circular rotating disk with constant rotation in various industrial mechanisms using equilibrium equations, geometric relations and stress functions. In this way, research on a thin uniform and homogeneous circular disk under constant rotation is considered. The rotating motion produces centrifugal acceleration on each element of the rotating disk, and this rotating motion becomes the source of external loading for the mentioned problem. Additional exterior loadings are not assumed in this problem. It is comfortable to handle the centrifugal force loading by relating it to a body force... 

    Electrochemical Deposition of Composite Coatings of Nickel - Silicon Carbide Under Pulsed Current Using a Rotating Disk Electrode

    , M.Sc. Thesis Sharif University of Technology Zarghami, Vahid (Author) ; Ghorbani, Mohammad (Supervisor)
    Abstract
    Ni-SiC composite coatings are widely used in industry (equipment high wear resistance coatings, corrosion resistant coatings, ship and boiler coatings, . . . ). Its unique properties in high wear resistance, corrosion resistance and tribological properties, researchers tend to investigate this coating. This study covers Ni-SiC composite coating under pulsed current using a rotating disk electrode to achieve optimal conditions in synthsis process, increaseing hardness and resistance to corrosion in coatings.waats' bath established for electrodeposition in this research. Bath parameters, current parameters and hydrodynamic of solution is examined. Changing of current type from direct current... 

    Study of the effect of fluid flow on corrosion rate for simple carbon steel in aqueous solution using rotating disk electrode

    , Article 18th International Congress of Chemical and Process Engineering, CHISA 2008, Prague, 24 August 2008 through 28 August 2008 ; 2008 Bastani, D ; Mohagheghi, A ; Sharif University of Technology
    2008
    Abstract
    The influence of fluid flow on the corrosion of simple carbon steel ST37 (AISI 1020) in aqueous solution of Bandar-Abbas gas well was studied at 25°C under air-saturated condition. The mechanism and kinetic of corrosion in different hydrodynamic conditions were determined using a rotating disk electrode. Increasing the velocity of rotating disk ≤ 1000 rpm caused an augmentation in corrosion rate from 9.89 to 18.95 mill in./yr. Increasing the velocity beyond 1000 rpm changed the corrosion mechanism so that the activation polarization will control the corrosion process, and the variation in corrosion rates was due to various corrosion mechanisms rather than mass transfer of reactant component.... 

    Thermoelastic creep analysis of a functionally graded various thickness rotating disk with temperature-dependent material properties

    , Article International Journal of Pressure Vessels and Piping ; Volume 111-112 , 2013 , Pages 63-74 ; 03080161 (ISSN) Hosseini Kordkheili, S. A ; Livani, M ; Sharif University of Technology
    2013
    Abstract
    A semi-analytical solution for rotating axisymmetric disks made of functionally graded materials was previously proposed by Hosseini Kordkheili and Naghdabadi [1]. In the present work the solution is employed to study thermoelastic creep behavior of the functionally graded rotating disks with variable thickness in to the time domain. The rate type governing differential equations for the considered structure are derived and analytically solved in terms of rate of strain as a reduced to a set of linear algebraic equations. The advantage of this method is to avoid simplifications and restrictions which are normally associated with other creep solution techniques in the literature. The thermal... 

    Analytical solution of generalized coupled thermoelasticity problem in a rotating disk subjected to thermal and mechanical shock loads

    , Article Journal of Thermal Stresses ; Volume 39, Issue 12 , 2016 , Pages 1588-1609 ; 01495739 (ISSN) Entezari, A ; Kouchakzadeh, M. A ; Sharif University of Technology
    Taylor and Francis Ltd  2016
    Abstract
    In this article, a fully analytical solution of the generalized coupled thermoelasticity problem in a rotating disk subjected to thermal and mechanical shock loads, based on Lord–Shulman model, is presented. The general forms of axisymmetric thermal and mechanical boundary conditions as arbitrary time-dependent heat transfer and traction, respectively, are considered at the inner and outer radii of the disk. The governing equations are solved analytically using the principle of superposition and the Fourier–Bessel transform. The general closed form solutions are presented for temperature and displacement fields. To validate the solutions, the results of this study are compared with the... 

    Alteration of corrosion and nanomechanical properties of pulse electrodeposited Ni/SiC nanocomposite coatings

    , Article Journal of Alloys and Compounds ; Vol. 598 , 2014 , Pages 236-242 ; ISSN: 09258388 Zarghami, V ; Ghorbani, M ; Sharif University of Technology
    Abstract
    Nickel/silicon carbide composite electrodeposits were prepared on a rotating disk electrode (RDE), under pulse current condition. The effect of pulse parameters, current density, SiC content in the electrolyte on the codeposition of SiC were studied. Afterwards, the effect of codeposited SiC amount was investigated on electrochemical behavior and nanomechanical properties of coatings. The coatings were analyzed with Scanning Electron Microscopy (SEM), linear polarization, nanoindentation and Atomic Force Microscopy (AFM). The Ni-SiC electrocomposites, prepared at optimum conditions, exhibited improved nanomechanical properties in comparison to pure nickel electrodeposits. With increasing... 

    Solution of Coupled Thermoelasticity Problem in Rotating Disks with Constant and Variable Thickness

    , Ph.D. Dissertation Sharif University of Technology Entezari, Ayoob (Author) ; Kouchakzadeh, Mohammad Ali (Supervisor)
    Abstract
    The main purpose of this dissertation is to study thermoelastic behaviors in rotating disks subjected to thermal shock loads based on the generalized and classic theories of coupled thermoelasticity. To this end, this research has been carried out in two stages. In the first stage, thermoelasticity problems in an axisymmetric rotating disk with constant thickness made of a homogeneous isotropic material are analytically solved. In this stage, based on the classical and generalized coupled theories, and dynamic and quasi-static uncoupled theories, an analytical method based on the Fourier-Bessel transform is employed to obtain the thermoelastic solutions. Then, closed-form formulations are... 

    Analysis of micro-rotating disks based on the strain gradient elasticity

    , Article Acta Mechanica ; Vol. 225, issue. 7 , 2014 , pp. 1955-1965 ; ISSN: 00015970 Danesh, V ; Asghari, M ; Sharif University of Technology
    Abstract
    In this paper, the mechanical behavior of micro-rotating disks is investigated utilizing the strain gradient theory. The governing equation and boundary conditions are derived utilizing the variational method. The analytical solution for the derived equation is also presented. As a case study, some numerical results are presented to emphasize the importance of utilization of non-classical theories such as the strain gradient elasticity instead of the classical continuum theory in dealing with micro-rotating disks  

    Thermoelastic analysis of a functionally graded rotating disk

    , Article Composite Structures ; Volume 79, Issue 4 , 2007 , Pages 508-516 ; 02638223 (ISSN) Hosseini Kordkheili, A ; Naghdabadi, R ; Sharif University of Technology
    2007
    Abstract
    A semi-analytical thermoelasticity solution for hollow and solid rotating axisymmetric disks made of functionally graded materials is presented. The radial domain is divided into some virtual sub-domains in which the power-law distribution is used for the thermomechanical properties of the constituent components. Imposing the necessary continuity conditions between adjacent sub-domains, together with the global boundary conditions, a set of linear algebraic equations are obtained. Solution of the linear algebraic equations yields the thermoelastic responses for each sub-domain as exponential functions of the radial coordinate. Some results for the stress, strain and displacement components... 

    Mixing in a novel double coaxial spinning disks reactor

    , Article Chemical Engineering and Processing - Process Intensification ; Volume 159 , 2021 ; 02552701 (ISSN) Mirzaei, M ; Molaei Dehkordi, A ; Bagheri Farahani, H ; Sharif University of Technology
    Elsevier B.V  2021
    Abstract
    High mixing efficiency that is of great importance in various industrial processes is a significant feature of spinning disk reactors. This work was focused on the characterization of mixing in a new reactor called Double Spinning Disk Reactor (DSDR) by adopting a competitive parallel reaction system known as iodide–iodate test reaction. The proposed DSDR consists of two coaxial rotating disks that the feeds are introduced into the gap between them. The mixing improves with an increase in the rotational speed of the disk, the radial distance of the feed introduced through the lower disk, and its number of feed points, while an increase in each of the feed flow rate and the distance between... 

    Integration of CFD and Nelder-Mead algorithm for optimization of MOCVD process in an atmospheric pressure vertical rotating disk reactor

    , Article International Communications in Heat and Mass Transfer ; Volume 43 , April , 2013 , Pages 138-145 ; 07351933 (ISSN) Abedi, S ; Farhadi, F ; Boozarjomehry, R. B ; Sharif University of Technology
    2013
    Abstract
    In this work, optimization of metalorganic chemical vapor deposition process for uniform layer thickness with especial attention to reactor geometric parameters as decision variables is presented. A numerical solution to a steady thermal flow associated with multi-species and chemical reactions in atmospheric pressure axisymmetrical rotating disk reactor by the CFD technique is obtained. Such a simulation is conducted on the assumption that the low Mach number flow is laminar. Then the validation of the numerical results with the benchmark solutions is conducted. Finally, integrating the CFD simulator with an optimization program, based on the Nelder-Mead algorithm, as a new approach is... 

    Kinetic studies of glucose electrocatalytic oxidation on GC/Ni electrode

    , Article International Journal of Chemical Kinetics ; Volume 44, Issue 11 , 2012 , Pages 712-721 ; 05388066 (ISSN) Danaee, I ; Jafarian, M ; Forouzandeh, F ; Gobal, F ; Sharif University of Technology
    2012
    Abstract
    Nickel-modified glassy carbon electrode (GC/Ni) prepared by galvanostatic deposition was used for the electrocatalytic oxidation of glucose in alkaline solutions where different electrochemical methods were employed. In cyclic voltammetry studies, in the presence of glucose an increase in the peak current of the oxidation of nickel hydroxide is followed by a decrease in the corresponding cathodic current. This suggests that the oxidation of glucose is being catalyzed through mediated electron transfer across the nickel hydroxide layer comprising nickel ions of various valence states. Under the chronoamperometric regime, the reaction followed a Cottrellian behavior and the diffusion... 

    Electrochemical oxidation of saccharose on copper (hydr)oxide-modified electrode in alkaline media

    , Article Cuihua Xuebao/Chinese Journal of Catalysis ; Volume 31, Issue 11 , 2010 , Pages 1351-1357 ; 02539837 (ISSN) Jafarian, M ; Rashvand Avei, M ; Danaee, I ; Gobal, F ; Mahjani, M. G ; Sharif University of Technology
    2010
    Abstract
    A stable copper (hydr)oxide-modified electrode was prepared in 0.5 mol/L NaOH solution by cyclic voltammetry in the range of -250 to 1000 mV. It can be used for electrochemical studies in the range of -250 to 1000 mV without interfering peaks because there is no oxidation of copper. During an anodic potential sweep, the electro-oxidation of saccharose on Cu occurred by the formation of CuIII and this reaction also occurred in the early stages of the reversed cycle until it is stopped by the negative potentials. A mechanism based on the electro-chemical generation of CuIII active sites and their subsequent consumption by saccharose was proposed, and the rate law and kinetic parameters were... 

    A preliminary study of the electro-catalytic reduction of oxygen on Cu-Pd alloys in alkaline solution

    , Article Journal of Electroanalytical Chemistry ; Volume 647, Issue 1 , 2010 , Pages 66-73 ; 15726657 (ISSN) Gobal, F ; Arab, R ; Sharif University of Technology
    2010
    Abstract
    Copper-palladium alloys of different compositions are electrodeposited on nickel from aqueous solutions. These alloys are characterized by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The catalytic activity of these alloys toward oxygen reduction reaction (ORR) in alkaline solution is investigated using rotating disk electrode (RDE). The number of electrons transferred per O2 molecule (n) obtained at different potentials is close to 2 at low overpotential indicating HO2- formation and gradually increases to 4 at higher overpotentials indicating full reduction to OH-. It is shown that Cu-Pd alloys are better electrocatalysts than Pd with Pd-Cu-1 having 24.5%... 

    Heat transfer and pressure drop characteristics of nanofluid in unsteady squeezing flow between rotating porous disks considering the effects of thermophoresis and Brownian motion

    , Article Advanced Powder Technology ; Volume 27, Issue 2 , Volume 27, Issue 2 , 2016 , Pages 564-574 ; 09218831 (ISSN) Saidi, M. H ; Tamim, H ; Sharif University of Technology
    Elsevier B.V  2016
    Abstract
    In this study, the unsteady three dimensional nanofluid flow, heat and mass transfer in a rotating system in the presence of an externally applied uniform vertical magnetic field is investigated. This study has different applications in rotating magneto-hydrodynamic (MHD) energy generators for new space systems and also thermal conversion mechanisms for nuclear propulsion space vehicles. The important effects of Brownian motion and thermophoresis have been included in the model of nanofluid. The governing equations are non-dimensionalized using geometrical and physical flow field-dependent parameters. The velocity profiles in radial, tangential and axial directions, pressure gradient,... 

    Elasticity formulation for motion equations of couple stress based micro-rotating disks with varying speeds

    , Article Mechanics Based Design of Structures and Machines ; 2019 ; 15397734 (ISSN) Bagheri, E ; Asghari, M ; Sharif University of Technology
    Taylor and Francis Inc  2019
    Abstract
    The elasticity formulation for equations of motion of micro-rotating disks in the presence of angular acceleration as well as the corresponding boundary conditions are developed based on the non-classical continuum theory of couple stress. The system of the boundary value problem is derived on the basis of the variational method. Analytical elasticity solutions to the system of equations are then provided. Based on the elasticity solution, the mechanical responses, including the displacement and stress fields, for varying-speed micro-rotating disks are studied. In a numerical case study, the effect of the couple stresses on the distribution of stress and displacement components are... 

    Elasticity formulation for motion equations of couple stress based micro-rotating disks with varying speeds

    , Article Mechanics Based Design of Structures and Machines ; 2019 ; 15397734 (ISSN) Bagheri, E ; Asghari, M ; Sharif University of Technology
    Taylor and Francis Inc  2019
    Abstract
    The elasticity formulation for equations of motion of micro-rotating disks in the presence of angular acceleration as well as the corresponding boundary conditions are developed based on the non-classical continuum theory of couple stress. The system of the boundary value problem is derived on the basis of the variational method. Analytical elasticity solutions to the system of equations are then provided. Based on the elasticity solution, the mechanical responses, including the displacement and stress fields, for varying-speed micro-rotating disks are studied. In a numerical case study, the effect of the couple stresses on the distribution of stress and displacement components are... 

    Effects of couple stresses on the in-plane vibration of micro-rotating disks

    , Article JVC/Journal of Vibration and Control ; Volume 26, Issue 13-14 , 2020 , Pages 1246-1259 Bagheri, E ; Jahangiri, M ; Asghari, M ; Sharif University of Technology
    SAGE Publications Inc  2020
    Abstract
    Micro-rotating disks are extensively used in micro-electromechanical systems such as micro-gyroscopes and micro-rotors. Because of the sensitivity of these elements, enough knowledge about the mechanical behavior of these structures is an essential matter for designers and fabricators. The small-scale effects on the in-plane free vibration of such micro-disks present an important aspect of the mechanical behavior of these elements. The small-scale effects on the in-plane free vibration of these micro-disks are investigated in this study using the modified couple stress theory. By using the Hamilton principle, the partial differential equations governing the coupled radial and tangential... 

    Investigation of a Novel Microfluidic Device for Label-Free Ferrohydrodynamic Cell Separation on a Rotating Disk

    , Article IEEE Transactions on Biomedical Engineering ; Volume 67, Issue 2 , 2020 , Pages 372-378 Shamloo, A ; Besanjideh, M ; Sharif University of Technology
    IEEE Computer Society  2020
    Abstract
    Negative magnetophoresis is a novel and attractive method for continuous microparticle sorting inside a magnetic medium. In this method, diamagnetic particles are sorted based on their sizes using magnetic buoyancy force and without any labeling process. Although this method provides some attractive features, such as low-cost fabrication and ease of operation, there are some obstacles that adversely affect its performance, especially for biological applications. Most types of magnetic media, such as ferrofluids, are not biocompatible, and the time-consuming process of sample preparation can be threatening to the viability of the cells within the sample. Furthermore, in this method, both the...