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Simulation of corrosion protection methods in reinforced concrete by artificial neural networks and fuzzy logic
, Article Journal of Electrochemical Science and Engineering ; Volume 12, Issue 3 , 2022 , Pages 511-527 ; 18479286 (ISSN) ; Shokrgozar, A ; Afshar, A ; Afshar, A ; Sharif University of Technology
International Association of Physical Chemists
2022
Abstract
In this study, the effect of protection methods regarding the corrosion decrement of steel in concrete was simulated by artificial neural networks (ANNs) and fuzzy logic (FL) approaches. Hot dip galvanizing as a protective coating, Ferrogard 901 corrosion inhibitor, a pozzolanic component, such as fly ash (FA) and micro-silica (MS), and eventually rebar AISI-304 were employed in concrete. Reinforced concrete samples were held under impressed voltage of 30 V in 3.5 % NaCl electrolyte for 350 hours toward a stainless-steel auxiliary electrode. Corrosion currents have been modelled using feed forward back propagation ANNs and FL methods. The results demonstrate good consistency between...
Simulation of the effects of pozzolanic additives and corrosion inhibitor on the corrosion of reinforced concrete by artificial neural networks
, Article Revista Romana de Materiale/ Romanian Journal of Materials ; Volume 49, Issue 4 , 2019 , Pages 535-543 ; 15833186 (ISSN) ; Nobakhti, A ; Shokrgozar, A ; Afshar, A ; Sharif University of Technology
Fundatia Serban Solacolu
2019
Abstract
In this research, we simulate the corrosive behavior of steel reinforcements on 5 different mixtures to investigate the effect of two powerful protective methods, including pozzolanic additives and corrosion inhibitor on concrete, by artificial neural networks (ANNs). Related to this model, fly ash (FA), micro silica (MS), and slag were used as pozzolanic materials at an optimum 25%, 10%, and 25% of cement weight, respectively. Moreover, Ferrogard 901 as an inhibitor was also utilized. The producer recommends using12 kg/m3 to get the best possible results. The non-linear corrosion of concrete into a marine solution (3.5% NaCl) was simulated by the feed forward back propagation (FFBP)...
Simulation of the effects of pozzolanic additives and corrosion inhibitor on the corrosion of reinforced concrete by artificial neural networks
, Article Revista Romana de Materiale/ Romanian Journal of Materials ; Volume 49, Issue 4 , 2019 , Pages 535-543 ; 15833186 (ISSN) ; Nobakhti, A ; Shokrgozar, A ; Afshar, A ; Sharif University of Technology
Fundatia Serban Solacolu
2019
Abstract
In this research, we simulate the corrosive behavior of steel reinforcements on 5 different mixtures to investigate the effect of two powerful protective methods, including pozzolanic additives and corrosion inhibitor on concrete, by artificial neural networks (ANNs). Related to this model, fly ash (FA), micro silica (MS), and slag were used as pozzolanic materials at an optimum 25%, 10%, and 25% of cement weight, respectively. Moreover, Ferrogard 901 as an inhibitor was also utilized. The producer recommends using12 kg/m3 to get the best possible results. The non-linear corrosion of concrete into a marine solution (3.5% NaCl) was simulated by the feed forward back propagation (FFBP)...
Corrosion resistance evaluation of rebars with various primers and coatings in concrete modified with different additives
, Article Construction and Building Materials ; Volume 262 , 2020 ; Jahandari, S ; Rasekh, H ; Shariati, M ; Afshar, A ; Shokrgozar, A ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Corrosion of steel rebars in concrete can reduce the durability of concrete structures in coastal environments. The corrosion rate of these concrete structures can be reduced by using suitable concrete additives and coating on rebars. This paper investigates the corrosion resistance of steel rebars by the addition of pozzolanic materials including fly ash, silica fume, polypropylene fibers, and industrial 2-dimethylaminoethanol (FerroGard 901) inhibitors to the concrete mixture. Three different types of rebars including mild steel rebar st37, and two stainless steel reinforcements, AISI 304 and AISI 316, were used. Various types of primer and coating including alkyd based primer, hot-dip...
Flow stress dependence on the grain size in alumina dispersion-strengthened copper with a bimodal grain size distribution
, Article Materials Science and Engineering A ; Volume 518, Issue 1-2 , 2009 , Pages 41-46 ; 09215093 (ISSN) ; Simchi, A ; Sharif University of Technology
2009
Abstract
The grain size dependence of flow stress in Cu-2.7 vol.%Al2O3 (15 nm) composite with a bimodal structure was studied. It is shown that the yield strength obeys the Hall-Petch equation when an appropriate value of average grain size based on the "rule of mixture" is employed. The Hall-Petch constants (σ0ε and kε) are proportional to strain as ε0.5. An equation for flow stress as a function of true strain and average grain size is proposed. The effect of alumina nanoparticles on the yield strength is shown to be related to large amounts of dislocations density. © 2009 Elsevier B.V. All rights reserved
Abnormal grain growth in alumina dispersion-strengthened copper produced by an internal oxidation process
, Article Scripta Materialia ; Volume 58, Issue 11 , 2008 , Pages 966-969 ; 13596462 (ISSN) ; Simchi, A ; Sharif University of Technology
2008
Abstract
Cu-2.7 vol.% Al2O3 (15 nm) composite was synthesized by an internal oxidation and hot extrusion process. The grain growth at elevated temperatures was studied and compared with extruded copper powder. Abnormal grain growth via a mechanism analogous to that of site-saturated phase transformation was observed. The critical grain size for the abnormal growth was determined to be 1.1 ± 0.2 μm. The growth rate decreased with time until the grain size approaching a final value ranging from 7.9 to 13.3 μm depending on the temperature. © 2008 Acta Materialia Inc
Diffuse emissions of particles from iron ore piles by wind erosion
, Article Environmental Engineering Science ; Volume 28, Issue 5 , 2011 , Pages 333-339 ; 10928758 (ISSN) ; Torkian, A ; Sharif University of Technology
2011
Abstract
Industrial air pollution from point and nonpoint sources of steel complexes has drawn increasingly more public attention in the past decades. Previous research efforts have been more concentrated on point sources of particulate emissions from these complexes. However, wind-induced particulate emissions from iron ore storage piles not only result in ambient air pollution but also increase economic adverse effects to the industry by loss of process raw materials. Experiments were conducted to assess the impact of wind speed and humidity on particulate emission rates from iron ore storage piles. A wind-generating system and specific iron ore, experimental piles (L:W:H of 30:11.5:5 cm) were...
Electrodeposition of Ni-Fe alloys in the presence of complexing agents
, Article Russian Journal of Electrochemistry ; Volume 38, Issue 11 , 2002 , Pages 1173-1177 ; 10231935 (ISSN) ; Dolati, A. G ; Afshar, A ; Sharif University of Technology
2002
Abstract
The electrodeposition of binary Ni-Fe alloys is studied in chloride-based solutions with organic additives. Specific codeposition composition of the electrolyte and operating variables are taken for deposition a wide range of Ni-Fe deposits. Results reveal that in solutions containing sodium citrate and glycolic acid, the nickel content always increases with the current density and nickel concentration. Therefore, nickel reduction rate and the Ni/Fe ratio in the deposits increase. The anomalous codeposition of iron is minimized and the quality of the alloy deposits is improved with the combination of sodium citrate and glycolic acid. Scanning electron micrographs show that, with addition of...
Properties, crystallization mechanism and microstructure of lithium disilicate glass-ceramic
, Article Journal of Non-Crystalline Solids ; Volume 356, Issue 4-5 , 2010 , Pages 208-214 ; 00223093 (ISSN) ; Nemati, A ; Shabanian, M ; Afshar, A ; Sharif University of Technology
2010
Abstract
In this study, lithium disilicate glass-ceramic in the TiO2-ZrO2-Li2O-CaO-Al2O3-SiO2 system was investigated for dentistry applications by incorporation of P2O5 and Nb2O5 as nucleation agent. The influence of the particles size (nano and submicron size) and nucleating agents on the crystalline phases, microstructure, crystallization mechanism and mechanical properties were investigated. Our data indicated that in ceramic glass with nano and submicron P2O5, the main crystalline phase was lithium disilicate. The results also showed that change of P2O5 particle's size had significant effect on the crystalline phases and microstructure. By replacement of submicron P2O5 with submicron Nb2O5,...
A simple route to synthesize zirconia antistatic thin films on glass substrates and their application to polymer-based composites
, Article Materials Chemistry and Physics ; Volume 244 , 1 April , 2020 ; Dolati, A ; Afshar, A ; Palardy, G ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
In this study, zirconia antistatic coatings were synthesized by a simple dip coating sol-gel route on glass substrates, then applied to polymer-based composites to potentially improve their dust or water repellent capabilities. The coating solution contained a precursor (ZrCl4), solvent (isopropanol) and coupling agent. FTIR spectra confirmed ZrO2 and ZrO compounds in both solution and antistatic coating. FE-SEM images indicated ZrO2 fibers’ thickness was controlled by changing ZrCl4 concentration (150 g–15 g ZrCl4/l) or relative humidity (20%–60%) during coating drying. Fibers grew thicker when decreasing the former or increasing the latter. The surface electrical resistivity for all...
Microstructure-corrosion resistance relationship of Direct and Pulse Current electrodeposited Zn-TiO2 nanocomposite coatings
, Article Ceramics International ; Vol. 41, issue. 1 , 2014 , pp. 217-224 ; ISSN: 02728842 ; Ghorbani, M ; Afshar, A ; Sharif University of Technology
2014
Abstract
Zinc-TiO2 nano-composite coatings were synthesized by Direct Current (DC) and Pulse Current (PC) electrodeposition techniques. The effects of the plating parameters on the microstructure, codeposition percentage of TiO2 and corrosion behavior were investigated. The coatings morphology presents hexagonal grains perpendicularly oriented to the surface. Under DC conditions, TiO2 content of the coatings decreased with increasing TiO2 concentration of the electrolyte. Increasing applied current and TiO2 concentration in the bath leads to a fine microstructure with corrosion currents as low as 2.7 μA/cm2. Under PC conditions, incorporation rate of nanoparticles tends to increase with increasing...
Joint process and quality control of a continuously stirred tank reactor with non-Gaussian process noise
, Article IET Control Theory and Applications ; Volume 6, Issue 5 , 2012 , Pages 651-661 ; 17518644 (ISSN) ; Nobakhti, A ; Wang, H ; Sharif University of Technology
2012
Abstract
This study proposes a multi-objective control algorithm for simultaneous process and quality control in non-Gaussian stochastic batch processes. The objective is to control a non-Gaussian process so that each batch is delivered within a pre-specified time. During each batch, the process is controlled by a fixed-parameter PI controller. Between any two adjacent batches the controller parameters are updated by a differential evolution algorithm so that the integral squared of tracking error, entropy of tracking error, integral of absolute processing time error and entropy of processing time error are minimised. the proposed algorithm is applied to a batch continuously stirred tank reactor...
Effect of pulse current parameters on the mechanical and corrosion properties of anodized nanoporous aluminum coatings
, Article Materials Chemistry and Physics ; Volume 183 , 2016 , Pages 490-498 ; 02540584 (ISSN) ; Ahmadi, Sh ; Afshar, A ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
In this study, the effects of pulse current parameters on corrosion resistance and mechanical properties of anodized coatings were evaluated. Hardness measurements, polarization and electrochemical impedance spectroscopy tests were employed to investigate the mechanical properties and corrosion behavior of these coatings. Also, field emission scanning electron microscopy (FE-SEM) was used to analyze the surface morphology and microstructure of the coatings. It was found that the properties of anodized coatings were dependent on various parameters, among which, time, temperature and pulse current parameters (current density limit, frequency and duty cycle) were optimized. Analysis of Variance...
Direct solution of the parametric stochastic distribution control problem
, Article Proceedings of the IEEE Conference on Decision and Control, 15 December 2009 through 18 December 2009, Shanghai ; 2009 , Pages 2616-2621 ; 01912216 (ISSN) ; 9781424438716 (ISBN) ; Nobakhti, A ; Wang, H ; Sharif University of Technology
2009
Abstract
The Stochastic Distribution Control (SDC) problem is a generalised form of the minimum variance control problem where non-Gaussian noise distributions are encountered. The problem has been previously solved using two alternative approaches. When it is assumed that the output Probability Distribution Function (PDF) is measurable, then a parameterized controller is obtained. If on the other hand this assumption is removed (which corresponds to most practical cases), then the controller found is no longer parameterisable (i.e. it is a control action sequence). Both these approaches have thus far been solved using local Newtonian methods. In this paper a third alternative is presented which...
Corrosion resistance and photocatalytic activity evaluation of electrophoretically deposited TiO 2 -rGO nanocomposite on 316L stainless steel substrate
, Article Ceramics International ; Volume 45, Issue 11 , 2019 , Pages 13747-13760 ; 02728842 (ISSN) ; Parvizy, S ; Afshar, A ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
TiO 2 -rGO nanocomposite coatings were obtained by electrophoretic deposition (EPD) technique of TiO 2 nanoparticles and graphene oxide (GO) on stainless steel substrate. First, GO particles were synthesized using a modified Hummers' method. GO was reduced electrochemically to form a coating in the presence of nano-sized TiO 2 particles. The influences of different parameters such as GO concentration, coupling co-electro-deposition parameters (electrophoretic duration and voltage) on thickness, surface morphology and, corrosion behavior of the as-synthesized TiO 2 -rGO nanocomposite coatings were systematically surveyed. The morphology and microstructure were investigated by field emission...
Electrophoretic deposition of nano-zirconia coating on AZ91D magnesium alloy for bio-corrosion control purposes
, Article Surface and Coatings Technology ; Volume 311 , 2017 , Pages 182-190 ; 02578972 (ISSN) ; Mohammadi, I ; Afshar, A ; Sharif University of Technology
Elsevier B.V
2017
Abstract
Magnesium alloys are considered as potential biodegradable biomaterials in hard tissue implants. However, the fast degradation rate of these alloys in the biological environment causes failure of the implant just prior to the desirable time. In the present work, in order to decrease and curb the bio-corrosion rate of AZ91D Magnesium alloy, zirconia, which is classified as a biocompatible ceramic, was coated on the alloy surface through electrophoretic deposition (EPD) technique. The effects of alterations in the EPD parameters such as current density, duration time and ZrO2 particles concentration on coating properties including thickness, morphology and adhesion were then characterized....
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) ; Mazaheri, M ; Afshar, A ; Sharif University of Technology
2005
Abstract
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...
Three dimensional bigravity
, Article Physical Review D - Particles, Fields, Gravitation and Cosmology ; Volume 81, Issue 4 , 2010 ; 15507998 (ISSN) ; Alishahiha, M ; Naseh, A ; Sharif University of Technology
2010
Abstract
In this paper, we explore some features of f-g theory in three dimensions. We show that the theory has both anti-de Sitter and de Sitter solutions, the wave solutions in both cases are also obtained. In particular, at a critical value of the coupling constant, we see that the model admits log gravity solutions, reminiscent of topologically massive gravity and new massive gravity. We have also studied a class of exact static spherically symmetric black hole solutions in the model
Characterization of sol-gel derived silver/fluor-hydroxyapatite composite coatings on titanium substrate
, Article Surface and Coatings Technology ; Volume 352 , 2018 , Pages 522-528 ; 02578972 (ISSN) ; Abbasi Khazaei, B ; Afshar, A ; Sharif University of Technology
Elsevier B.V
2018
Abstract
A composite coating containing silver, fluoride and hydroxyapatite (Ag-FHA) was developed on titanium substrate by sol-gel method. Triethylphosphite, hydrated calcium nitrate, ammonium fluoride and silver nitrate were used respectively, as P, Ca, F and Ag precursors with a Ca:P ratio 1.67 and concentration of silver was 0.3 wt%. Coatings were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and atomic absorption spectrometry (AAS). Potentiodynamic polarization measurements in simulated body fluid proved corrosion protection caused by both Ag-FHA coatings. Antibacterial activity of coatings against...
Electrochemical characterization of the Ni-Fe alloy electrodeposition from chloride-citrate-glycolic acid solutions
, Article Materials Chemistry and Physics ; Volume 77, Issue 2 , 2003 , Pages 352-358 ; 02540584 (ISSN) ; Dolati, A. G ; Ghorbani, M ; Sharif University of Technology
2003
Abstract
Cyclic voltammetry and transient time (τ) measurements have been used to characterize the system, while potentiostatic I-t transients have been recorded to obtain the nucleation and growth mechanism. The electrodeposition of nickel, iron and nickel-iron alloys on the platinum was studied by electrochemical techniques in the presence of complexing compounds. The cyclic voltammetry results clearly show that the electrodeposition of nickel, iron and nickel-iron alloys is a diffusion-controlled process with a typical nucleation mechanism. The redox potentials of the Ni and Fe are shifted to more cathodic potentials in the complexing electrolytes. In addition, the current transients reveal that...