Search for: surface-characteristics
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    Ultrasonic-assisted cylindrical grinding of Alumina-zirconia ceramics

    , Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) ; Volume 2 A , Volume 2 A , 2013 ; 9780791856185 (ISBN) Tawakoli, T ; Akbari, J ; Zahedi, A. M ; ASME ; Sharif University of Technology
    American Society of Mechanical Engineers (ASME)  2013
    Due to its vast applications and stochastic nature, grinding has been the subject of investigations and modifications for decades. Applying ultrasonic vibration in grinding has been a successful innovation introducing benefits such as reduced forces and temperature, improved surface quality, and making higher removal rates possible. In this work a set-up is developed for utilizing ultrasonic vibrations in cylindrical grinding. This is done by rotating and simultaneously vibrating the workpiece material. The set-up is used for cylindrical grinding of Alumina-zirconia ceramic as a difficult-to-grind and widely used industrial ceramic. Optimized parameters for efficient grinding and surface... 

    Surface micromorphology and fractal geometry of Co/CP/X (X = Cu, Ti, SM and Ni) nanoflake electrocatalysts

    , Article RSC Advances ; Volume 6, Issue 32 , 2016 , Pages 27228-27234 ; 20462069 (ISSN) Ţəlu, Ş ; Solaymani, S ; Bramowicz, M ; Naseri, N ; Kulesza, S ; Ghaderi, A ; Sharif University of Technology
    Royal Society of Chemistry  2016
    This paper analyses the three-dimensional (3-D) surface texture of Co/CP/X (X = Cu, Ti, SM and Ni, CP: carbonaceous paste) nanoflakes prepared electrochemically using a conventional three electrode system. The surface chemical composition of the samples was investigated by X-ray photoelectron spectroscopy (XPS). Surface images were recorded using scanning electron microscopy (SEM) and analyzed by means of the fractal geometry. Statistical, fractal and functional surface properties of the prepared samples were computed. The statistical functions applied to the SEM data were employed in order to characterise the surfaces topographically (in amplitude, spatial distribution and pattern of... 

    Enhancement of surface adsorption-desorption rates in microarrays invoking surface charge heterogeneity

    , Article Sensors and Actuators, B: Chemical ; Volume 242 , 2017 , Pages 956-964 ; 09254005 (ISSN) Abdollahzadeh, M ; Saidi, M. S ; Sadeghi, A ; Sharif University of Technology
    Elsevier B.V  2017
    This investigation is devoted to the influences of non-uniform wall characteristics on the surface adsorption-desorption rates in an electrokinetic microarray. Utilizing already explored electroosmotic and electrophoretic velocities, the species transport equations are solved by a finite-volume-based numerical approach. Uniform, sinusoidal, and pulse-like distributions of the zeta potential are considered in the analysis. The developed model is validated by comparing the results with those of two analytical solutions that are derived for limiting conditions. The results reveal that, in some cases, the surface charge heterogeneity can reduce the saturation time by more than 60%. The efficacy... 

    Experimental investigation of the effect of copper electrodeposition on the aluminum surface and addition of ethylene glycol on boiling heat transfer coefficient

    , Article Heat and Mass Transfer/Waerme- und Stoffuebertragung ; 2021 ; 09477411 (ISSN) Azadi Milani, P ; Mahdi, M ; Abarghooei, A ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2021
    In this research, the effect of surface characteristics on boiling heat transfer has been investigated experimentally. For this purpose, a device with the ability to automatically record the liquid temperature of the inlet and outlet of the test area, calculate the coefficient of boiling heat transfer, and heat flux has been developed. The automatic temperature stability of the working fluid and the ability to investigate the effect of surfaces with different characteristics (in terms of material and surface structure) on the boiling heat transfer parameters are the most important features of this device. The performance of the experimental setup was evaluated by the modified "Chen" equation... 

    Properties of alumina nanoparticle-filled nitrile-butadiene-rubber/ phenolic-resin blend prepared by melt mixing

    , Article Polymer Composites ; Volume 30, Issue 9 , 2009 , Pages 1290-1298 ; 02728397 (ISSN) Faghihi, M ; Shojaei, A ; Sharif University of Technology
    Effect of alumina nanoparticle (ANP) on the properties of rubber compounds based on nitrile-butadiene-rub- ber (NBR) and NBR/phenolic-resin (PH) blend is examined. To investigate the surface characteristics of the nanoparticles on the performance of nanoalumina- filled compounds, trimethoxyvinylsilane (MVS) is attached chemically on the surface of ANP through an appropriate functionalization process. Various NBR and NBR/Ph compounds filled with ANP and functionalized ANP (f-ANP) are prepared via melt mixing using traditional open two-roll mill. Microscopic analysis carried out by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) reveals good dispersion of... 

    Fabrication of durable superhydrophobic surfaces using PDMS and beeswax for drag reduction of internal turbulent flow

    , Article Applied Surface Science ; Volume 513 , 2020 Pakzad, H ; Liravi, M ; Moosavi, A ; Nouri Borujerdi, A ; Najafkhani, H ; Sharif University of Technology
    Elsevier B.V  2020
    Nowadays, one of the biggest concerns in the world is increasing the CO2 emissions and global warming due to the over-consumption of fossil fuels. In addition, under the intense market competition, the demand for more efficient systems with higher performance and lower energy consumption has escalated. Since the drag force contributes to a considerable percentage of the energy loss and reducing the performance, a large number of studies have been conducted to improve the surface characteristics and, subsequently, declining the drag force. Making the surface superhydrophobic is one of the most effective ways for this purpose. In this work, two different superhydrophobic surfaces using SiO2... 

    Optical properties, microstructure, and multifractal analyses of ZnS thin films obtained by RF magnetron sputtering

    , Article Journal of Materials Science: Materials in Electronics ; Volume 31, Issue 7 , 2020 , Pages 5262-5273 Shakoury, R ; Arman, A ; Ţălu, Ş ; Ghosh, K ; Rezaee, S ; Luna, C ; Mwema, F ; Sherafat, K ; Salehi, M ; Mardani, M ; Sharif University of Technology
    Springer  2020
    The morphology, structure and optical properties of zinc sulfide (ZnS) thin films prepared through radio-frequency (RF) magnetron sputtering have been analyzed using atomic force microscopy (AFM), UV–Vis–NIR spectrophotometry, X-ray diffraction, and multifractal analyses. The X-ray diffraction patterns revealed that all ZnS thin films show a single peak at around 29.6°, which has been ascribed to the (111) planes of sphalerite phase, indicating that the growth direction of the films is the [111] direction. UV–Vis–NIR transmittance spectra were used to determine the refractive index of the samples, their thickness, and their band gap energy, showing the optical and semiconductor properties a... 

    Atomistic insight into the behavior of ions at an oil-bearing hydrated calcite surface: implication to ion-engineered waterflooding

    , Article Energy and Fuels ; Volume 35, Issue 16 , 2021 , Pages 13039-13054 ; 08870624 (ISSN) Badizad, M. H ; Koleini, M. M ; Greenwell, H. C ; Ayatollahi, S ; Ghazanfari, M. H ; Sharif University of Technology
    American Chemical Society  2021
    This research provides an atomistic picture of the role of ions in modulating the microstructural features of an oil-contaminated calcite surface. This is of crucial importance for the rational design of ion-engineered waterflooding, a promising technique for enhancing oil recovery from carbonate reservoirs. Inspired by a conventional lab-scale procedure, an integrated series of molecular dynamics (MD) simulations were carried out to resolve the relative contribution of the major ionic constituent of natural brines (i.e., Na+, Cl-, Mg2+, Ca2+, and SO42-) when soaking an oil-bearing calcite surface in different electrolyte solutions of same salinity, namely, CaCl2, MgCl2, Na2SO4, MgSO4, and... 

    Surface chemistry of atmospheric plasma modified polycarbonate substrates

    , Article Applied Surface Science ; Volume 257, Issue 23 , September , 2011 , Pages 9836-9839 ; 01694332 (ISSN) Yaghoubi, H ; Taghavinia, N ; Sharif University of Technology
    Surface of polycarbonate substrates were activated by atmospheric plasma torch using different gas pressure, distance from the substrates, velocity of the torch and number of treatments. The modifications were analyzed by contact angle measurements, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and UV-vis spectrophotometry. Plasma treatment caused the surface characteristics to become more hydrophilic as measured by the water contact angle, which decreased from 88° to 18°. The decrease in contact angle was mainly due to oxidation of the surface groups, leading to formation of polar groups with hydrophilic property. XPS results showed an increase in the intensity of... 

    Comparison and assessment of spatial downscaling methods for enhancing the accuracy of satellite-based precipitation over Lake Urmia Basin

    , Article Journal of Hydrology ; Volume 596 , 2021 ; 00221694 (ISSN) Karbalaye Ghorbanpour, A ; Hessels, T ; Moghim, S ; Afshar, A ; Sharif University of Technology
    Elsevier B.V  2021
    Estimating precipitation at high spatial-temporal resolution is vital in manifold hydrological, meteorological and water management applications, especially over areas with un-gauged networks and regions where water resources are on the wane. This study aims to evaluate five downscaling methods to determine the accuracy and efficiency of which on generating high-resolution precipitation data at annual and monthly scales. To establish precipitation-Land surface characteristics relationship, environmental factors, including Normalized Difference Vegetation Index (NDVI), Land Surface Temperature (LST) and Digital Elevation Model (DEM), were considered as proxies in the spatial downscaling... 

    Direct production of carbon nanotubes decorated with Cu2O by thermal chemical vapor deposition on Ni catalyst electroplated on a copper substrate

    , Article Journal of Nanoparticle Research ; Volume 13, Issue 10 , October , 2011 , Pages 4681-4689 ; 13880764 (ISSN) Nayeb Sadeghi, S ; Shafiekhani, A ; Vesaghi, M. A ; Sharif University of Technology
    Carbon nanotubes (CNTs) decorated with Cu2O particles were grown on a Ni catalyst layer deposited on a Cu substrate by thermal chemical vapor deposition from liquid petroleum gas. Ni catalyst nanoparticles with different sizes were produced in an electroplating system at 45 °C using the corrosive effect of H2SO4 which was added to solution. These nanoparticles provide the nucleation sites for CNT growth avoiding the need for a buffer layer. The surface morphology of the Ni catalyst films and CNT growth over this catalyst was studied by scanning electron microscopy (SEM). High temperature surface segregation of the Cu substrate into the Ni catalyst layer and its exposition to O2 at... 

    Sol-gel-based silver nanoparticles-doped silica - Polydiphenylamine nanocomposite for micro-solid-phase extraction

    , Article Analytica Chimica Acta ; Volume 886 , July , 2015 , Pages 56-65 ; 00032670 (ISSN) Bagheri, H ; Banihashemi, S ; Sharif University of Technology
    Elsevier  2015
    A nanocomposite of silica-polydiphenylamine doped with silver nanoparticles (Ag-SiO2-PDPA) was successfully synthesized by the sol-gel process. For its preparation, PDPA was mixed with butanethiol capped Ag nanoparticles (NPs) and added to the silica sol solution. The Ag NPs were stabilized as a result of their adsorption on the SiO2 spheres. The surface characteristic of nanocomposite was investigated using scanning electron microscopy (SEM). In this work the Ag-SiO2-PDPA nanocomposite was employed as an efficient sorbent for micro-solid-phase extraction (μ-SPE) of some selected pesticides. An amount of 15 mg of the prepared sorbent was used to extract and... 

    Observer design for topography estimation in atomic force microscopy using neural and fuzzy networks

    , Article Ultramicroscopy ; Volume 214 , 2020 Rafiee Javazm, M ; Nejat Pishkenari, H ; Sharif University of Technology
    Elsevier B.V  2020
    In this study, a novel artificial intelligence-based approach is presented to directly estimate the surface topography. To this aim, performance of different artificial intelligence-based techniques, including the multi-layer perceptron neural, radial basis function neural, and adaptive neural fuzzy inference system networks, in estimation of the sample topography is investigated. The results demonstrate that among the designed observers, the multi-layer perceptron method can estimate surface characteristics with higher accuracy than the other methods. In the classical imaging techniques, the scanning speed of atomic force microscope is restricted due to the time required by the oscillating... 

    Reinforced polydiphenylamine nanocomposite for microextraction in packed syringe of various pesticides

    , Article Journal of Chromatography A ; Volume 1222 , January , 2012 , Pages 13-21 ; 00219673 (ISSN) Bagheri, H ; Ayazi, Z ; Es'haghi, A ; Aghakhani, A ; Sharif University of Technology
    Reinforced polydiphenylamine (PDPA) nanocomposite was synthesized by oxidation of diphenylamine in 4molL-1 sulfuric acid solution containing a fixed amount of carbon nanotubes (CNTs) in the presence of cetyltrimethylammonium bromide (CTAB). The surface characteristic of PDPA and PDPA/CNT nanocomposites was investigated using scanning electron microscopy (SEM). The prepared PDPA/CNT nanocomposite was used as an extraction medium for microextraction in packed syringe (MEPS) of selected pesticides from aquatic environment. The effect of CNT doping level and the presence of surfactant on the extraction capability of nanocomposite was investigated and it was revealed that when 4% (w/w) of CNT in...