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    Evaluation of the Effect of Olive Leaf Extract (Olive Leaf) as a Green Inhibitor on Corrosion of Concrete Steel Reinforcements in the Persian Gulf Sea Water Simulator

    , M.Sc. Thesis Sharif University of Technology Behroozi, Mohammad Hossein (Author) ; Afshar, Abdollah (Supervisor)
    Abstract
    In this project, olive leaf extract has been investigated as a green corrosion inhibitor or in other words environmentally friendly for rebars embedded in concrete in the Persian Gulf Sea water simulator. Olive leaves were prepared by ultrasonic method at 50 ° C with the help of ethanol solvent. The water-ethanol solvent was 70:30 and the resulting extract was immediately applied to the concrete mix in specified doses. Portland cement type 2 according to ISIRI-389-96 standard has been used to prepare concrete. The resulting extract powder was added to the samples in four different doses: 2%, 4%, 6%, 8% by weight of cement to prove the inhibitory function as well as the cathodic or inhibitory... 

    Produce of Antibacterial Composite Coating of PTFE+Ag+TiO2 On 316SS and Study Its Properties

    , M.Sc. Thesis Sharif University of Technology Sheikhzadeh, Mohammad Sajjad (Author) ; Afshar, Abdollah (Supervisor)
    Abstract
    This research investigated the corrosion and antibacterial properties of PTFE+TiO2/Ag coating and its adhesion to 316L stainless steel. To increase adhesion, polydopamine coating was created as an intermediate layer by chemical deposition method on stainless steel, then PTFE + TiO2 coating was created on the sample by immersion method, and then silver nanoparticles were applied as the third layer by chemical deposition method. According to the polarization curves, the most corrosion-resistant coatings with corrosion current density of 3.34×10-5 and 3.25×10-4 μA are coatings PTFE+TiO2 and PTFE/PTFE+TiO2/Ag respectively. In terms of antibacterial activity, according to the non-growth halo... 

    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) Afshar, A ; 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... 

    Formation & Properties of Zn–Ca– Mn Tri – Cation’s Phosphate Coating on St37 Steels

    , M.Sc. Thesis Sharif University of Technology Rasouli, Hassanali (Author) ; Afshar, Abdollah (Supervisor) ; Ghorbani, Mohammad (Supervisor)
    Abstract
    Addition of heavy metal cations such as manganese and nickel in low zinc phosphating bath increases the corrosion resistance of coatings and provides more suitable substrates for painting (especially electrophoretic painting). In addition, due to accelerating property and low cost availability of heavy metal cations such as Mn, multi– cationic phosphating is cost effective. In the present study, chemical composition and operating parameters of zinc - calcium - manganese Tri- cationic phosphating solution were optimized. Then the effects of various parameters such as phosphating time, bath temperature and pH on properties of coating were investigated. According to the results, about 1 g/L was... 

    Production of Zn-Tio2 Nanocomposite Coating by Electrochemical Method and Investigation of its Properties

    , M.Sc. Thesis Sharif University of Technology Sajjadnezhad, Mohammad (Author) ; Ghorbani, Mohammad (Supervisor) ; Afshar, Abdollah (Supervisor)
    Abstract
    Pure zinc coating and Zn-TiO2 composite coating were deposited from two methods: Direct and Pulse Current from a sulphate bath. D.C. section, current density and particle concentration in electrolyte were investigated. Moreover in Pulse section, frequency, duty cycle and maximum current density were investigated as parameters. Morphological properties of these coatings were investigated by FE-SEM and corrosion behavior by potentiodynamic polarization in 1M NaCl. In D.C. section, in investigation of the effect of current density, an optimum was observed in case of obtaining the highest amount of deposited particles at 0.1 A/cm2 and amount of 2.93%. This amount is the highest one in D.C.... 

    Praparation of Nanometric Platinum Coatings on Carbon Substrate (Pt/C) for Catalytic Plates of Fuel Cells

    , M.Sc. Thesis Sharif University of Technology Behjat, Saeed (Author) ; Ghorbani , Mohammad (Supervisor) ; Afshar, Abdollah (Supervisor)
    Abstract
    With increasing pollution and decrease in global reservoirs of fossil fuels, a lot of interest has been attracted to fuel cells as efficient and clean energy sources. Polymeric (membrane) fuel cells are special type of fuel cells, which can be built in small dimensions and power. These cells use hydrogen (and oxygen or air) and produce water. In these cells, platinum is used as electrode (and electrocatalyst) both in anode and cathode, due to its low overvoltage for both hydrogen and oxygen. To increase the efficiency of these coatings, it is best to produce platinum particles with maximum area and it automatically leads to nanometric particles. In this thesis, platinum particles are... 

    Modeling and Simulation of Hydro-Power Station and Determination and Evaluation of Governor Design Specifications

    , M.Sc. Thesis Sharif University of Technology Amir Nazmi Afshar, Peyman (Author) ; Durali, Mohammad (Supervisor)
    Abstract
    The main objective of this project is to take the first steps in designing power plants governor in Iran. In this work, we obtain a realistic model of a hydro-power plant including hydraulic characteristics from the dam to the outlet tail water, mechanically including: the turbine, the gates and all mechanical and dynamic parts, and electrically including generators, transformers and the consumption network. The model is used to simulate different working modes of turbine operation. The Bond Graph method is used for deriving the system equations and MATLAB software for simulations. A conceptual design of the governor is done and the governor model is combined with the turbine model. Using... 

    Fabrication of Ni -P -MoS2 Composite Coating by Electroless Deposition and Evaluation of Its Tribological Properties

    , M.Sc. Thesis Sharif University of Technology Majidian, Maryam (Author) ; Ghorbani, Mohammad (Supervisor) ; Afshar, Abdollah (Supervisor)
    Abstract
    Adding solid lubricant particles such as PTFE, Graphite and MoS2, has major influence on electroless composite nickel coatings in order to make low friction surfaces. Among these lubricants, MoS2 has attracted great attention due to its highest stability under wearing condition. In this work Ni-P-MoS2 composite coatings using MoS2 nano-particles have been made and in the next step, we evaluated tribological properties of these coatings. For exploring these coatings different experiments were utilized, like Scanning Electron Microscope study (SEM), chemical composition analysis exploiting AAS and XRF method, and thickness measurements. Two kinds of surfactants, CTAB and PVP, have been applied... 

    Trafic Prediction in MANET by Computational Intelligence Techniques

    , M.Sc. Thesis Sharif University of Technology Torkamanian Afshar, Mahsa (Author) ; Manzuri, Mohammad Taghi (Supervisor)
    Abstract
    Mobile Ad-Hoc Networks (MANETs) have been studied as one of the most important technologies in the mid to late 1990s. There are several research works on types of network traffic modeling and prediction. Therefore, a very important issue is to make prediction on traffic-flows that each node handles. Because of this, prediction permits us to improve and increase the performance of the network. This project is a contributing effort to improve the traffic packets prediction by Neural Networks in MANET. The main goal of this thesis is about the recovery of data after crisis in phenomenal roads and highways. Our goal is recognizing phenomenal crisis-points in roads. In this thesis packets are... 

    Fabrication and Characterization of Carbon-based Perovskite Solar Cells

    , Ph.D. Dissertation Sharif University of Technology Ramin Afshar, Camellia (Author) ; Mohammadi, Mohammad Reza (Supervisor)
    Abstract
    Hole-transporter-free perovskite solar cells with structure of TiO2/ZrO2/C triple-layer scaffold filled with perovskite are great alternative to the conventional ones due to the possibility of making full printable low-cost and stable devices. In the present work, the impacts of the structures of the quadruple layer scaffold in the form of TiO2/ZrO2/NiO/C and triple layer scaffold in the form of TiO2/ZrO2/C on their photovoltaic performance are studied. In addition, the effects of thickness and deposition method of each layer were investigated as well as the effect of compounding of the carbon counter electrode. All devices were constructed by a simple printable method. Electrochemical... 

    Effect of TiO2 Coating on Efficiency of Black Electroless Ni-P Solar Absorber

    , M.Sc. Thesis Sharif University of Technology Razmjoo Khollari, Mohammad Amin (Author) ; Ghorbani, Mohammad (Supervisor) ; Afshar, Abdollah (Supervisor)
    Abstract
    In this thesis Blackening of electroless nickel-phosphorous coating and the effect of TiO2 anti-reflection coating on optical properties of coating was investigated. In the first step, electroless nickel coatings with different amounts of phosphorous on 1050 aluminium substrate deposited. In second step, blackening of coatings by chemical and electroche-mical methods have studied and in final step, effect of TiO2 antireflection coatings with different amount of Pluronic F127 on the optimum black surface and properties of coating investigated. Chemical blackening performed in nitric acid and effect of acid concenteration, Blackening time and temperature studied. optimized condition was... 

    Electrodeposition of Cu/WC Nanocomposite

    , M.Sc. Thesis Sharif University of Technology Barmaki, Mohammad Reza (Author) ; Dolati, Abolghasem (Supervisor) ; Afshar, Abdollah (Supervisor)

    The Effect of Olive Leaf Green Inhibitor on the Corrosion Resistance of Steel Reinforcement in Geopolymer Concrete Pore Solution

    , M.Sc. Thesis Sharif University of Technology Khalili, Mohammad Reza (Author) ; Afshar, Abdollah (Supervisor) ; Hosseini, Payam (Co-Supervisor)
    Abstract
    In this research project, the aim was to investigate the potential of olive leaf extract as an eco-friendly inhibitor for enhancing the corrosion resistance of reinforcing steel in simulated geopolymer concrete pore solution (GCP) containing chloride ions. The inhibitory effects of olive leaf extract were evaluated using various electrochemical techniques as well as scanning electron microscopy. The main phenolic compounds present in olive leaf extract were identified using high performance liquid chromatography (HPLC). Moreover, the elements and chemical bonds present in the surface passive film of the steel bar immersed in the olive leaf inhibiting system were characterized using... 

    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) Afshar, A ; 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) Afshar, A ; 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)... 

    A CDN Architecture to be used in SDN

    , M.Sc. Thesis Sharif University of Technology Afshar Safavi, Roohollah (Author) ; Hemmatyar, Ali Mohammad Afshin (Supervisor)
    Abstract
    In recent years, the usage of Internet bandwidth has been increased by emerging applications such as Video on Demand (VoD).As the popularity of VoD increases among the Internet users, some new problems like bandwidth limitations and congestion embark. For solving mentioned problems, Content Delivery Networks (CDN) has been introduced. Using CDN approaches either in ISP or organization is also known as Telco CDN. Generally implementing CDN approaches to process all requests either in ISP or organization can cause bottleneck. On the other hand, Software Defined Networks (SDN) could bring us new tools and opportunities which enables us to implement novel methods to confront these problems.... 

    Fabrication and Characterization of Dye-Sensitized Solar Cells based on the hybrids of Multi Wall Carbon Nanotube and Nanostructured TiO2

    , Ph.D. Dissertation Sharif University of Technology Mokarami Ghartavol, Hajar (Author) ; Afshar, Abdollah (Supervisor) ; Mohammadi, Mohammad Reza (Supervisor)
    Abstract
    This study presents a facile sol-gel template-assisted route to prepare CNT-TiO2 hybrid structures (CTH) for dye-sensitized solar cell (DSSC) applications. Non-covalent functionalized multi-walled carbon nanotubes (CNTs) with average diameter of 80 nm are used as the template for TiO2 deposition. The X-ray diffraction reveals that the hybrid structures are composed of primary anatase TiO2 nanoparticles with the average crystallite size of 12 nm, after heat treatment at 450°C in air atmosphere. TEM and FESEM images show that the shell thickness of the coated TiO2 on CNTs’ outmost walls varies between 60 to 120 nm, when the ratio of CNTs:TiO2 is 10wt. %. Photovoltaic measurements demonstrate... 

    Evaluation of Explainability Methods for Breast Cancer Histopathological Image Classification

    , M.Sc. Thesis Sharif University of Technology Afshar Mazandaran, Pardis (Author) ; Fatemizadeh, Emadeddin (Supervisor) ; Rohban, Mohammad Hossein (Supervisor)
    Abstract
    The analysis of histopathological images is essential for the accurate diagnosis of cancer and the development of treatment plans. With significant advancements in deep learning and the adoption of advanced models such as convolutional neural networks, the accuracy and efficiency of image analysis have greatly improved. However, these models are often referred to as "black boxes," and one of their major challenges is the lack of transparency in their decision-making processes. This opacity reduces trust in their results, particularly in sensitive medical fields. To address this issue, the field of Explainable Artificial Intelligence (XAI) has emerged, aiming to provide clear and... 

    Corrosion resistance evaluation of rebars with various primers and coatings in concrete modified with different additives

    , Article Construction and Building Materials ; Volume 262 , 2020 Afshar, A ; 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) Afshar, A ; 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