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rotating-disks
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Electrochemical Deposition of Composite Coatings of Nickel - Silicon Carbide Under Pulsed Current Using a Rotating Disk Electrode
, M.Sc. Thesis Sharif University of Technology ; 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...
Solution of Coupled Thermoelasticity Problem in Rotating Disks with Constant and Variable Thickness
, Ph.D. Dissertation Sharif University of Technology ; 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...
CFD Simulation of Rotating Disk Apparatus for Obtaining Reaction Rate of HCl and Carbonate Minerals
, M.Sc. Thesis Sharif University of Technology ; Shad, Saeed (Supervisor) ; Bazargan, Mohammad (Supervisor)
Abstract
Today, acidizing is one of the most important methods for stimulation and increasing the productivity of oil and gas wells. In Iran and other oil-rich countries, a large amount of money is invested every year in acidizing operations. Due to complex nature of acidizing of an oil formation, it’s very difficult to design an optimized and successful operation. Therefore, many research projects have been performed for understanding the physics of the dissolution of reservoir rock by acid and the behavior of wormholes and secondary reactions. The most important prerequisite of these researches is the perfect knowledge of acid and mineral reaction kinetics. One of the most common experiments to...
Analysis of Micro Rotating Disk with Angular Acceleration Based on the Non-Classical Continuum Mechanics
, M.Sc. Thesis Sharif University of Technology ; Asghari, Mohsen (Supervisor)
Abstract
Incapability of the classical continuum mechanics theory to justify the experimental observations of the mechanical response of the small-scale structures and parts motivated the researchers to pursue the introduction and utilization of the non-classical continuum theories for analysis and design of such structures and parts. In this paper, utilizing the modified couple stress theory and the strain gradient theory as well-known and powerful non-classical continuum theories, the mechanical response, including the displacement and stress fields, for micro-rotating disks with angular acceleration is investigated. The governing differential equations of motion and the corresponding boundary...
CFD Simulation of Rotating Disk Apparatus for Determining Reaction Equation Parameters of VES and Carbonate Minerals
, M.Sc. Thesis Sharif University of Technology ; Bazargan, Mohammad (Supervisor) ; Jamshidi, Saeed (Supervisor)
Abstract
Acidizing operation is performed in oil and gas reservoirs with the aim of overcoming formation damages, increasing permeability and reducing skin factor. In carbonate reservoir, the hydrochloric acid increases the permeability of the areas around the well to a more than its initial value by dissolving part of the formation minerals. Considering that most of Iran's oil and gas reservoirs are in the category of carbonate reservoirs, it is important to study the reaction kinetics of carbonate minerals and acids used in acidizing operation. The complex and multifactorial nature of the acidizing operation in the reservoirs has made it very difficult to design a successful and optimal operation....
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 ; 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...
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 ; 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...
Analysis of micro-rotating disks based on the strain gradient elasticity
, Article Acta Mechanica ; Vol. 225, issue. 7 , 2014 , pp. 1955-1965 ; ISSN: 00015970 ; 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 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) ; 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...
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) ; 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...
In-plane and transverse eigenmodes of high-speed rotating composite disks
, Article Journal of Applied Mechanics, Transactions ASME ; Volume 80, Issue 1 , 2013 ; 00218936 (ISSN) ; Abbas Jalali, M ; Sharif University of Technology
2013
Abstract
We apply Hamilton's principle and model the coupled in-plane and transverse vibrations of high-speed spinning disks, which are fiber-reinforced circumferentially. We search for eigenmodes in the linear regime using a collocation scheme, and compare the mode shapes of composite and isotropic disks. As the azimuthal wavenumber varies, the radial nodes of in-plane waves are remarkably displaced in isotropic disks while they resist such displacements in composite disks. The reverse of this phenomenon happens for transversal waves and the radial nodes move toward the outer disk edge as the azimuthal wavenumber is increased in composite disks. This result is in accordance with the predictions of...
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) ; 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...
Thermo-mechanical analysis of rotating disks with non-uniform thickness and material properties
, Article International Journal of Pressure Vessels and Piping ; Volume 98 , October , 2012 , Pages 95-101 ; 03080161 (ISSN) ; Hojjati, M. H ; Mahdavi, E ; Alashti, R. A ; Farrahi, G ; Sharif University of Technology
Elsevier
2012
Abstract
Theoretical and numerical analyses of rotating disks with non-uniform thickness and material properties subjected to thermo-mechanical loadings have been carried out by variable material properties (VMP), Runge-Kutta's (RK) and finite element (FE) methods. The material is assumed to be elastic-linear hardening. A power form function is used to describe the temperature gradient with the higher temperature at outer surface. Von-Mises theory has been used as failure criterion. The effects of geometry, material and thermal loading parameters as well as boundary conditions on radial, hoop and equivalent stress distributions which have not been studied in much detail in previous works have been...
Semi-exact solution for thermo-mechanical analysis of functionally graded elastic-strain hardening rotating disks
, Article Communications in Nonlinear Science and Numerical Simulation ; Volume 17, Issue 9 , 2012 , Pages 3747-3762 ; 10075704 (ISSN) ; Hojjati, M. H ; Farrahi, G. H ; Alashti, R. A ; Sharif University of Technology
Abstract
In this paper, distributions of stress and strain components of rotating disks with non-uniform thickness and material properties subjected to thermo-elasto-plastic loading are obtained by semi-exact method of Liao's homotopy analysis method (HAM) and finite element method (FEM). The materials are assumed to be elastic-linear strain hardening and isotropic. The analysis of rotating disk is based on Von Mises' yield criterion. A two dimensional plane stress analysis is used. The distribution of temperature is assumed to have power forms with the hotter point located at the outer surface of the disk. A mathematical technique of transformation has been proposed to solve the homotopy equations...
Semi-exact elastic solutions for thermo-mechanical analysis of functionally graded rotating disks
, Article Composite Structures ; Volume 93, Issue 12 , 2011 , Pages 3239-3251 ; 02638223 (ISSN) ; Hojjati, M. H ; Farrahi, G ; Alashti, R. A ; Sharif University of Technology
Abstract
In this paper, distributions of stress and strain components of rotating disks with non-uniform thickness and material properties subjected to thermo-elastic loading under different boundary conditions are obtained by semi-exact methods of Liao's homotopy analysis method (HAM), Adomian's decomposition method and He's variational iteration method (VIM). The materials are assumed to be perfectly elastic and isotropic. A two dimensional plane stress analysis is used. The distribution of temperature over the disk radius is assumed to have power forms with the higher temperature at the outer surface. The results of the three methods are compared with those obtained by Runge-Kutta's numerical...
Geometrical optimization of half toroidal continuously variable transmission using particle swarm optimization
, Article Scientia Iranica ; Volume 18, Issue 5 , 2011 , Pages 1126-1132 ; 10263098 (ISSN) ; Saadat Foumani, M ; Boroushaki, M ; Ekhtiari, M ; Dehghani, M ; Sharif University of Technology
Abstract
The objective of this research is geometrical optimization of half toroidal Continuously Variable Transmission (CVT) in order to achieve high power transmission efficiency. The dynamic analysis of CVT is implemented and contact between the disk and the roller is modeled viaelastohydrodynamic (EHL) lubrication principles. Computer model is created using geometrical, thermal and kinetic parameters to determine the efficiency of CVT. Results are compared by other models to confirm the model validity. Geometrical parameters are obtained by means of Particle Swarm Optimization (PSO) algorithm, while the optimization objective is to maximize the power transmission efficiency. Optimization was...
Temperature and thickness effects on thermal and mechanical stresses of rotating FG-disks
, Article Journal of Mechanical Science and Technology ; Volume 25, Issue 3 , 2011 , Pages 827-836 ; 1738494X (ISSN) ; Azadi, M ; Sharif University of Technology
Abstract
In the present paper, radial and hoop thermal and mechanical stress analysis of a rotating disk made of functionally graded material (FGM) with variable thickness is carried out by using finite element method (FEM). To model the disk by FEM, one-dimensional two-degree elements with three nodes are used. It is assumed that the material properties, such as elastic modulus, Poisson's ratio and thermal expansion coefficient, are considered to vary using a power law function in the radial direction. The geometrical and boundary conditions are in the shape of two models including thermal stress (model-A) and mechanical stress (model-B). In model-A there exists no pressure in both external and...
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 , March , 2016 , Pages 564–574 ; 09218831 (ISSN) ; Tamim, H ; Sharif University of Technology
Elsevier
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,...
Preparation of new titanium nitride-carbon nanocomposites in supercritical benzene and their oxygen reduction activity in alkaline medium
, Article Electrochimica Acta ; Volume 164 , May , 2015 , Pages 114-124 ; 00134686 (ISSN) ; Ghorbani, M ; Dolati, A ; Yashiro, H ; Outokesh, M ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
Titanium nitride-carbon nanocomposites are synthesized by the reaction of TiCl4 and NaN3 in supercritical benzene medium that also serves as a carbon source. The as-prepared precursors (SI, SII) are subjected to several heat treatments (SIII-SV). The synthesized nanoparticles are characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The samples are tested as electrocatalyst for oxygen reduction reaction in an alkaline electrolyte. It is shown that the electrocatalytic properties of the synthesized nanoparticles are...
Synthesis-structure-performance correlation for poly-aniline-Me-C non-precious metal cathode based on mesoporous carbon catalysts for oxygen reduction reaction in low temperature fuel cells
, Article Renewable Energy ; Volume 77 , 2015 , Pages 558-570 ; 09601481 (ISSN) ; Samiee, L ; Fattahi, M ; Seifkordi, A. A ; Shoghi, F ; Maghsodi, A ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
In this work, attempt is made to development of active non-precious metal catalysts (NPMCs) for the oxygen reduction reaction in polymer electrolyte fuel cells (PEFCs) based on the heat treatment of poly-aniline/transition metal/carbon precursors. All the materials have been characterized by X-ray diffraction (XRD) small and wide angle, N2 adsorption-desorption isotherms, high-resolution transmission electron microscopy (TEM), Scanning electron microscope (SEM) and X-ray photo-electron spectroscopy (XPS). Moreover for electrochemical evaluation of samples, Rotating Disk electrode (RDE) technique and Fuel Cell test were employed. The results showed that onset potential for the optimized...