Search for: surface-roughness
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    Electrophoretic deposition of titanium dioxide nano-powders films in isopropanol as a solvent

    , Article International Journal of Modern Physics B ; Volume 22, Issue 18-19 , 2008 , Pages 2989-2994 ; 02179792 (ISSN) Ghorbani, M ; Roushan Afshar, M ; Sharif University of Technology
    World Scientific Publishing Co. Pte Ltd  2008
    In this study, titanium dioxide nano powders were electrophoretically deposited on the stainless steel in Isopropanol and Triethanolamine as a solvent and dispersant, respectively. The effects of deposition parameters including deposition voltage (5 to 20 V) and deposition time (5 to 60 s) on the microstructure and surface topography were examined by scanning electron microscope (SEM) and scanning probe microscope (SPM), respectively. In addition, the effects of these deposition parameters on packing density were investigated. This research revealed that substrate surface is fully covered with increasing deposition voltage and deposition time. Therefore packing density of deposited films is... 

    Height fluctuations and intermittency of V2O5 films by atomic force microscopy

    , Article Journal of Physics Condensed Matter ; Volume 15, Issue 12 , 2003 , Pages 1889-1898 ; 09538984 (ISSN) Iraji Zad, A ; Kavei, G ; Rahimi Tabar, M. R ; Vaez Allaei, S. M ; Sharif University of Technology
    The spatial scaling law and intermittency of the V2O5 surface roughness has been investigated by atomic force microscopy. The intermittency of the height fluctuations has been checked by two different methods, first, by measuring the scaling exponent of the qth moment of height-difference fluctuations i.e. Cq = <|h(x1) - h(x2)|q>, and second, by defining the generating function Z(q, N) and generalized multi-fractal dimension Dq. These methods predict that there is no intermittency in the height fluctuations. The observed roughness and dynamical exponents can be explained by numerical simulation on the basis of the forced Kuramoto-Sivashinsky equation  

    Etched glass surfaces, atomic force microscopy and stochastic analysis

    , Article Physica A: Statistical Mechanics and its Applications ; Volume 375, Issue 1 , 2007 , Pages 239-246 ; 03784371 (ISSN) Jafari, G. R ; Reza Rahimi Tabar, M ; Iraji zad, A ; Kavei, G ; Sharif University of Technology
    The effect of etching time scale of glass surface on its statistical properties has been studied using atomic force microscopy technique. We have characterized the complexity of the height fluctuation of an etched surface by the stochastic parameters such as intermittency exponents, roughness, roughness exponents, drift and diffusion coefficients and found their widths in terms of the etching time. © 2006 Elsevier B.V. All rights reserved  

    An effective image based surface roughness estimation approach using neural network

    , Article 2006 World Automation Congress, WAC'06, Budapest, 24 June 2006 through 26 June 2006 ; 2006 ; 1889335339 (ISBN); 9781889335339 (ISBN) Akbari, A. A ; Milani Fard, A ; Goodarzvand Chegini, A ; Sharif University of Technology
    IEEE Computer Society  2006
    The accurate measurement of surface roughness is essential in ensuring the desired quality of machined parts. The most common method of measuring the surface roughness of machined parts is using a surface profile-meter with a contact stylus, which can provide direct measurements of surface profiles. This method has its own disadvantageous such as workpiece surface damage due to mechanical contact between the stylus and the surface, In this paper we proposed a eontactless method using image processing and artificial neural network as a pattern classifier. Having trained the network for any specific workpiece with 10 sample patterns, the system would learn how to approximate the actual surface... 

    Structural Disorders of Graphene and Its Effects on Electronic Properties

    , M.Sc. Thesis Sharif University of Technology Abedpour, Nima (Author) ; Rahimi Tabar, Mohammad Reza (Supervisor)
    In this thesis we would like to investigate structural disorder of Graphene and its effect on electronic properties. Graphene is a one-layer crystal of Carbon atoms which was the first two dimensional crystal observed experimentally. Low energy current carriers on Graphene behave like mass-less Dirac fermions and this interesting electronic property attracts much attention on studying Graphene. Structural disorder of Graphene highly affects its electronic properties. We study thermal fluctuations of Graphene sheet, disorder super lattice, and static ripples, as structural disorders of Graphene. Disorders due to thermal fluctuations of graphene induce a disordered gauge field on the graphene... 

    Effect of the shear loading direction on shear behavior of rock and finding new empirical method for determining JRC by fractal dimension

    , Article Annual Conference of the Canadian Society for Civil Engineering 2007: Where the Road Ends, Ingenuity Begins, Yellowknife, NT, 6 June 2007 through 9 June 2007 ; Volume 1 , 2007 , Pages 259-267 Khosravi, A ; Sadaghiani, M. H ; Askari, M ; Khosravi, M ; Sharif University of Technology
    Effect of different conditions on shear behaviour of rock has been investigated by various researchers. As known, in larger scale the continuity of the rock material is interrupted by separated planes such as bedding planes, faults, shear zones, closure and the behaviour converts to be inelastic and anisotropic. Generally, discontinuities appear repeatedly in more than one preferential direction, creating a three dimensional structure, reducing its stiffness and shear strength as mechanical effects and increasing its transport velocity associated with discontinuity flow as hydraulic effects. They also make rock behavior more complex and different compared to the behavior of soil. According... 

    Investigation of Moving Oscillator’s Critical Speed on Single-Span Bridge with Roadway Roughness by FEM

    , M.Sc. Thesis Sharif University of Technology Rezaei Haftadori, Mahmoud (Author) ; Vafai, Abolhassan (Supervisor) ; Mofid, Masoud (Co-Advisor)
    In this research the critical speed of a moving oscillator on a single-span bridge with different support (boundary) conditions and by considering the presence of road surface roughness surface with finite element perspective is studied. Due to the fact that passing a moving load on top of the beam causes increased maximum stress and deformations in beam compared to static situation, therefore in reputable codes for bridge design such as AASHTO a dynamic amplification factor is used for designing bridge components. Moving oscillator is a more precise model compared to moving mass for modeling vehicles and the suspension system is modeled as a spring and damper and the moving mass is... 

    Ultrasonic assisted deep drilling of Inconel 738LC superalloy

    , Article Procedia CIRP, Leuven ; Volume 6 , April , 2013 , Pages 571-576 ; 22128271 (ISSN) Baghlani, V ; Mehbudi, P ; Akbari, J ; Sohrabi, M ; Sharif University of Technology
    Superalloys have a poor machinability and are often drilled using Electro Discharge Machining (EDM) methods. However EDM is a time-consuming process and has low surface integrity. Ultrasonic Assisted Drilling (UAD) technology is a modern method of drilling such materials. Although this method has very high capabilities, it has not been introduced widely to industry. In this study a special horn is designed and used to apply both rotation and vibration to drill bits. It can transfer power with high efficiency and has the capability to change tools easily. The setup is used to conduct deep drilling tests on Inconel 738LC with depth-to-diameter ratio of 10. The effect of ultrasonic vibration... 

    Spin relaxation in graphene nanoribbons in the presence of substrate surface roughness

    , Article Journal of Applied Physics ; Volume 120, Issue 5 , 2016 ; 00218979 (ISSN) Chaghazardi, Z ; Babaee Touski, Sh ; Pourfath, M ; Faez, R ; Sharif University of Technology
    American Institute of Physics Inc 
    In this work, spin transport in corrugated armchair graphene nanoribbons (AGNRs) is studied. We survey combined effects of spin-orbit interaction and surface roughness, employing the non-equilibrium Green's function formalism and multi-orbitals tight-binding model. Rough substrate surfaces have been statistically generated and the hopping parameters are modulated based on the bending and distance of corrugated carbon atoms. The effects of surface roughness parameters, such as roughness amplitude and correlation length, on spin transport in AGNRs are studied. The increase of surface roughness amplitude results in the coupling of σ and π bands in neighboring atoms, leading to larger spin... 

    The use of optical coherence tomography to analyze the efficacy of skin care products

    , Article Photonics in Dermatology and Plastic Surgery 2018, 27 January 2018 through 28 January 2018 ; Volume 10467 , 2018 ; 16057422 (ISSN); 9781510614192 (ISBN) Irani, S ; Turani, Z ; Fotouhi, A ; Daveluy, S ; Mehregan, D ; Chen, W ; Gelovani, J ; Nasiriavanaki, M ; The Society of Photo-Optical Instrumentation Engineers (SPIE) ; Sharif University of Technology
    SPIE  2018
    Background: Optical coherence tomography (OCT) is an imaging method that provides real time in situ visualization of human tissue at sub-micrometer resolution. Prior research shows OCT is suitable for imaging the epidermis. Method: In this study, we utilized OCT images to noninvasively measure the quantitative effect of a specialized antiaging product compared with a petrolatum control in a split-face trial. The images acquired with OCT were analyzed to determine the average surface roughness, Ra, and surface roughness depth, Rz, of the imaged skin. These values were measured over the duration of a 28-day trial. Results: The petrolatum treated skin showed a 2.1% and 2.9% decrease in Ra and... 

    Hydrophilicity and AFM Based Surface Statistical Analysis of SiO2/TiO2/Glass Bilayer

    , M.Sc. Thesis Sharif University of Technology Daryaei, Ebrahim (Author) ; Moshfegh, Alireza (Supervisor) ; Jafari, Golamreza (Supervisor)
    Titanium dioxide (TiO2) is important because of wide applications such as self cleaning surfaces and using in photoelectrochemical cells .Recent researches have shown that addition of silicon dioxide into TiO2 increases hydrophilicity of SiO2-TiO2 and improves surface properties. Until now a little research has been done on the double layer TiO2/SiO2 system; therefore, this system is suitable for studying. In general this thesis consists of theoretical and experimental parts .In the experimental part, multilayer systems of SiO2/TiO2/Glass have been selected (thickness of SiO2 is 20 nm) and surface morphology and hydrophilicity have been investigated by Atomic Force Microscopy (AFM) and... 

    Finite Element Simulation of Nanoindentation and Nanoscratch Tests on Nanocoatings

    , M.Sc. Thesis Sharif University of Technology Nazemian, Mohsen (Author) ; Farrahi, Gholamhossein (Supervisor) ; Fallah Rajabzadeh, Famida (Co-Advisor)
    Coatings are used in order to prevent wear, corrosion, thermal gradient reduction, surface strength improving and many other applications in industries. One of the common applications of coatings, is to prevent wear and surface abrasion. Hardness and friction coefficients are two parameters that determine the wear properties of a coating. Determining these parameters in very thin films is only possible by nanoindentation and nanoscratch tests. Surface hardness, young modulus and fracture toughness can be obtained using nanoindentation and friction coefficient is calculated from nanoscratch.
    Finite element method is widely used for simulating the nanoindentation and nanoscratch... 

    Self-encapsulation of single-texture CoSi2 nanolayer by TaSi2

    , Article Thin Solid Films ; Volume 516, Issue 18 , 31 July , 2008 , Pages 6008-6012 ; 00406090 (ISSN) Akhavan, O ; Azimirad, R ; Moshfegh, A. Z ; Sharif University of Technology
    In this work, we have studied single-texture formation of CoSi2 layer in heat-treated Co/Ta0.7W0.3/Si(100) structure. Moreover, self-encapsulation process of the CoSi2 layer and surface roughness of the encapsulated layer, as a contact layer, has been examined. A direct current magnetron co-sputtering technique was employed to deposit a 10 nm Ta0.7W0.3 alloy intermediate layer. After growth of the layer on the Si substrate, a 25 nm Co layer was deposited using thermal evaporation method. Post-annealing process of the films was treated in an N2(80%) + H2(20%) ambient in a temperature range from 400 to 1000 °C for 60 min. X-ray diffraction analysis showed that a single-texture CoSi2 layer with... 

    Effect of reduced frequency and surface roughness on an airfoil in plunging motion

    , Article 45th AIAA Aerospace Sciences Meeting 2007, Reno, NV, 8 January 2007 through 11 January 2007 ; Volume 2 , 2007 , Pages 860-869 ; 1563478900 (ISBN); 9781563478901 (ISBN) Soltani, M. R ; Rasi Marzabadi, F ; Sharif University of Technology
    An extensive experimental investigation to study the effect of the reduced frequency and surface grit roughness on an airfoil oscillating in plunging motion has been conducted. The application of surface grit roughness simulates surface irregularities that occur on the wind turbine blades. Data were taken at a Reynolds number of 0.42*10* and at a range of reduced frequencies, k=0.03-0.1. Tests were conducted at plunging amplitudes of ±10cm and ±15cm and at mean angles of attack of 0°, 10° and 18°. It was found that the width of the hysteresis loop, position of the figure-8 shape, slope of the lift coefficient curve and maximum lift force have been influenced by both oscillation frequency and... 

    Effect of surface contamination on the performance of a section of a wind turbine blade

    , Article 45th AIAA Aerospace Sciences Meeting 2007, Reno, NV, 8 January 2007 through 11 January 2007 ; Volume 19 , 2007 , Pages 13026-13036 ; 1563478900 (ISBN); 9781563478901 (ISBN) Soltani, M. R ; Birjandi, A. H ; Sharif University of Technology
    A series of low speed wind tunnel tests on a section of a 660 Kw wind turbine blade which is under constructer were conducted to examine the effects of distributed surface contamination on its performance characteristics. At first model was tested in the clean condition and after that it was tested with tree different types of roughness. The data shows that this particular airfoil is very sensitive to the applied surface roughness. For the contaminated model the roughness, 0.5mm height was distributed over the entire upper surface of the airfoil such that the distribution pattern was denser in the vicinity of the leading edge and thinner in the trailing edge area. Statistical data show that... 

    Analytical solution of turbulent problems using governing equation of cosserat continuum model

    , Article 2006 ASME International Mechanical Engineering Congress and Exposition, IMECE2006, Chicago, IL, 5 November 2006 through 10 November 2006 ; 2006 ; 08888116 (ISSN); 0791837904 (ISBN); 9780791837900 (ISBN) Ghasvari Jahromi, H ; Atefi, Gh ; Moosaie, A ; Hormozi, S ; Sharif University of Technology
    American Society of Mechanical Engineers (ASME)  2006
    In present paper the theory of the micropolar fluid based on a Cosserat continuum model has been applied for analysis of Couette flow and turbulent flow through rough pipes. The obtained results for the velocity field have been compared with known results from experiments done by Reichardt at Max Plank institute for fluids in Gottingen [1,2] and analytical solution of the problem from Gradient theory by alizadeh[3] for couette problem and with known results from experiments done by Nikuradse (1932).the boundary condition used here was the no slip one and Trostel's slip boundary condition[4].a good agreement between experimental results and the results of the problem for Reynolds near 18000... 

    Comparison of the unsteady loads of an airfoil in the pitching and plunging motions

    , Article 2006 ASME Joint U.S.- European Fluids Engineering Division Summer Meeting, FEDSM2006, Miami, FL, 17 July 2006 through 20 July 2006 ; Volume 2 FORUMS , 2006 , Pages 977-985 ; 0791847500 (ISBN); 9780791847503 (ISBN) Soltani, M ; Seddighi, M ; Rasi, F ; Sharif University of Technology
    American Society of Mechanical Engineers  2006
    A series of experiments were conducted on an oscillating airfoil in subsonic flow. The model was oscillated in two types of motions, pitch and plunge, at different velocities, and reduced frequencies. In addition, steady data were acquired and examined to furnish a baseline for analysis and comparison. The imposed variables of the experiment were reduced frequency, mean incident angle, amplitude of motion, and free stream velocity as well as the surface grit roughness. The unsteady aerodynamic loads were calculated using surface pressure measurements, 64 ports, along the chord for both upper and lower surfaces of the model. Particular emphases were placed on the effects of different type of... 

    Increasing the interfacial adhesion in poly(methyl methacrylate)/carbon fibre composites by laser surface treatment

    , Article Polymers and Polymer Composites ; Volume 14, Issue 6 , 2006 , Pages 585-589 ; 09673911 (ISSN) Nematollahzadeh, A ; Mousavi, S. A. S ; Tilaki, R. M ; Frounchi, M ; Sharif University of Technology
    Rapra Technology Ltd  2006
    The impact strength of poly(methyl methacrylate)/caibon (long) fibre composites for denture prosthesis applications was improved by fibre surface treatment. The carbon fibre surfaces were modified by Nd:YAG laser irradiation at 1064 nm wavelength. Laser light intensity was adjusted at 100 mj per pulse that only changed the fibre surface roughness and did not lead to fibre rupture, as verified by scanning electron microscopy. Increased surface roughness of the fibres improved the adhesion of poly(methyl methacrylate) to the fibre surface. Adhesion between the fibres and poly(methyl methacrylate) was evaluated by a tear-off method and by scanning electron microscopy. The results also suggest... 

    Contamination effects on the performance of a wind turbine blade section

    , Article 9th AIAA/ASME Joint Thermophysics and Heat Transfer Conference Proceedings, San Francisco, CA, 5 June 2006 through 8 June 2006 ; Volume 4 , 2006 , Pages 2801-2805 ; 1563478153 (ISBN); 9781563478154 (ISBN) Soltani, M. R ; Birjandi, A. H ; Sharif University of Technology
    A series of low speed wind tunnel tests on a section of a 660 Kw wind turbine blade were conducted to examine the effects of distributed surface contamination on its performance. The airfoil was a section of a wind turbine blade under construction. The performance of the section was measured in the following conditions: 1. Clean airfoil 2. Two types of zigzag roughness 3. Strip tape 4. Distributed contamination roughness Our preliminary data shows that the airfoil is very sensitive to the applied surface roughness. For the contamination model the roughness, 0.5mm height, is distributed over the entire upper surface of the airfoil. By putting the contamination roughness on the airfoil the... 

    Wear and friction characteristics of electrodeposited graphite-bronze composite coatings

    , Article Surface and Coatings Technology ; Volume 190, Issue 1 , 2005 , Pages 32-38 ; 02578972 (ISSN) Ghorbani, M ; Mazaheri, M ; Afshar, A ; Sharif University of Technology
    The wear and friction properties of G-Cu (Sn) composite coatings containing different amounts of graphite particles were examined. The presence of graphite particles improved antifriction properties of composite coatings. The effects of graphite percent in composite coating, tin content of matrix, load, speed and distance on the coefficient of friction and wear resistance of bronze-graphite composite coatings were studied. The results of the present studies revealed that hardness, wear resistance, coefficient of friction are dependent on volume percentage of graphite in composite coating. It was shown that the composite coating containing approximately 5.4 (vol.%) graphite and matrix with...