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    Optimization of Deposition of Micro- and Nano Particles in Filters and Porous Media

    , M.Sc. Thesis Sharif University of Technology Banihashemi Tehrani, Mostafa (Author) ; Moosavi, Ali (Supervisor) ; Sadrhosseini, Hani (Supervisor)
    This study is aimed at simulation of the flow of air and aerosol particles through a single square fibrous filter media made up of micro fiber as well as the importance and effect of different fiber’s cross-sectional shapes and arrangements on particle deposition and filtration efficiency. An understanding of the role of changing the laminar flow regime from laminar vortex shedding "(Re"=100" and Re"=200")" to subcritical flow "(Re"=1000")" developed for the first case. The study deals with parallel and staggered multi-fibrous filter media with circular, elliptical, and equilateral triangular micro fiber’s cross-sectional shape of the transient laminar vortex shedding flow "(Re"=200")" .... 

    Preparation and Study of Microstructural and Mechanical Properties of Ni-Tio2 Based Nanocomposite by Electrochemical Deposition Method

    , M.Sc. Thesis Sharif University of Technology Sariri, Farshid (Author) ; Mohammadi, Mohammad Reza (Supervisor) ; Ekrami, Ali Akbar (Co-Advisor)
    In the present work preparation of Ni-TiO2 films and their microstructural and mechanical properties were studied. For film preparation, DC current mode of electrochemical deposition method was used in Watts Nickel bath with different concentrations of transparent TiO2 sol up to 30 mL/L. It presents a new generation of nano Ni-TiO2 coating as a composite film for corrosion and erosion resistance applications. The best wear volume of 0.0046 mm3 was achieved for 30 mL/L Ni-TiO2 nanocomposite in comparison to 0.0071 mm3 for pure Ni film. Moreover, the coating hardness increased to ~345 HV50 for Ni-TiO2 nanocomposite. Corrosion rate of the coatings improved down to 1.10E-05 mm/year with addition... 

    Nickel Nano Particles Pulse Electrodeposition

    , M.Sc. Thesis Sharif University of Technology Afsari, Maryam (Author) ; Dolati, Abolghasem (Supervisor)
    Syntheses of coats including nickel nano-particles by electrodeposition have been
    investigated for over 10 years. A method of testing according to surface reply was chosen
    to reveal the effect of each pulse parameters (including duty cycle, frequency, average
    current density, off time (toff) and on time (ton)) and the effect of saccharin concentration
    on electroplating cathode efficiency, nanostructure. Pulse electroplating test of nickel was
    composed by 30 tests. Pulse electroplating with relatively high peak current density was
    employed and saccharine was added to increase deposition and rate of nickel nucleation on
    surface. According to the results of cathode... 

    Electrodeposition of Cu/WC Nanocomposite

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

    The Comparison Between TiN and Hard Chromium Coatings

    , M.Sc. Thesis Sharif University of Technology Ghominejad , Hanieh (Author) ; Dolati, Abolghasem (Supervisor)
    This research focuses on finding an appropriate method for increasing wear and corrosion resistance of hard coating TiN PVD and chromium. The substrate was made up of 42CrMo4 (DIN) steel (used for marine industries) and coated by TiN Arc PVD process and hard chromium electro-deposition. The results of these two coatings are compared and the better coating which is TiN Arc PVD is suggested. To find the best method for coating, several test studies are organized such as: the mechanical and tribological properties of TiN PVD and hard chromium coatings for wear and corrosion resistance applications are organized. The potentiodynamic polarization technique was used to measure the corrosion rate... 

    Fabrication of Gas Nanosensor based on 2D Nanostructure Titanium trisulfide/Graphene Heterojunction

    , Ph.D. Dissertation Sharif University of Technology Rafiefard, Nasim (Author) ; Iraji Zad, Azam (Supervisor) ; Sasanpour, Pezhman (Supervisor) ; Esfandiar, Ali (Co-Supervisor)
    Titanium trisulfide (TiS3), a transition metal chalcogenide, bears the potential to replace silicon, when taking the form of nanoflakes, due to its favorable band gap and optical response. In this work, first we investigate the response of TiS3 nanoflakes to gas detection through a careful quantum computational approach and a few succinct measurements. The computations are benchmarked and compared with a relevant experiment at each step, where their results/conclusions are discussed. The most stable surface of TiS3 particles is determined to (001), in agreement with the literature. The adsorption of 5 gas molecules is characterized through formulating and estimating their adsorption... 

    Growth of Two-Dimensional Molybdenum Disulfide Structures for Gas Sensing Application

    , Ph.D. Dissertation Sharif University of Technology Barzegar, Maryam (Author) ; Irajizad, Azam (Supervisor) ; Asgari, Reza (Supervisor)
    Molybdenum disulfide (MoS2) nanoflakes, a two-dimensional crystal with tunable bandgap depends on number of layers, is a promising candidate for future nanoelectronic devices. In the present research, flower shaped MoS2 nanoflakes have been synthesized via hydrothermal method. As part of the research, the growth of triangular MoS2 monolayer up to 10 micrometers has optimized by carring out several chemical vapor deposition experiments with varying deposition parameters. The prepared samples were characterized using optical, scanning electron, and atomic force microscopes, x-ray diffraction analysis, and Raman spectroscopy. Based on the experimental results, the growth mechanism has been... 

    Fabrication of Hybrid Supercapacitors Based on Graphene-Conducting Polymers and Some Metallic Oxides and Sulfides and Investigation of Their Electrochemical Behavior

    , Ph.D. Dissertation Sharif University of Technology Asen, Parvin (Author) ; Shahrokhian, Saeed (Supervisor) ; IrajiZad, Azam (Co-Supervisor)
    In this research, metal oxides and hydroxides with carbon materials and conductive polymers (CPs), as well as transition metal oxysulfide nanostructures (TMOS), hybrid of Tin oxide and sulfie and polyphasphate-reduced graphene oxide (PPO-RGO) have been used as an active electrode materials for supercapacitors. In the first section of thesis, Tiron and graphene oxide (GO) were used as an anionic dopants to increase the capacity and stability of polypyrrole (PPy). In order to increase the capacity of Tiron/PPy/GO nanocomposite, vanadium oxide (V2O5) was used. The Tiron/PPy/GO/V2O5 nanocomposite was deposited on a stainless steel (SS) as a substrate via one-step electrochemical deposition... 

    Using of SnS2 Nanostructured Layer as an Electron Transport Layer in the Perovskite Solar Cells

    , Ph.D. Dissertation Sharif University of Technology Haghighi, Maryam (Author) ; Mahdavi, Mohammad (Supervisor) ; Taghavinia, Nima (Supervisor) ; Mohammadpour, Raheleh (Co-Supervisor)
    In this research, we focus on study and investigation of the role of Tin(IV) Sulfide (SnS2) nanostructured layer as electron transport layer in perovskite and chalcogenide thin film solar cells. For this purpose, SnS2 powder was prepared through hydro/solvo-thermal method, utilizing different ratios of water and ethanol as solvent and various sulfur sources (thioacetamide and thiourea). Afterwards, different solvents were investigated to achieve a stable ink (about one month) with uniform dispersion. After determining the appropriate ink and powder, thin films of SnS2 were prepared employing spin coating, spray pirolysis and laser pulsed deposition (PLD) methods and characterized. With each... 

    Fabrication and Optimization of Organic Inorganic Perovskite Solar Cells Using Vapor Phase Deposition

    , Ph.D. Dissertation Sharif University of Technology Sedighi, Rahime (Author) ; Taghavinia, Nima (Supervisor) ; Tajabadi, Fariba (Supervisor)
    In this research, we focus on study and fabrication of organic inorganic solar cells. We use and optimize various methods such as one-step spin-coating, two-step sequential deposition and vapor-assisted solution process (VASP), to prepare high quality perovskite films. One-step deposition is simplest method for deposition of perovskite films. Although perovskite deposition by this method is very simple, the control of uniformity and surface film morphology is difficult. Chlorine inclusion, optimization of annealing conditions, and a sequential solution-based deposition method have been demonstrated to increase film coverage and uniformity. Hence, we use sequential deposition method for... 

    Monolithic Solar Cells with Dye or Perovskite Light Absorbent

    , Ph.D. Dissertation Sharif University of Technology Behrouznejad, Fatemeh (Author) ; Taghavinia, Nima (Supervisor)
    According to Iran's proper location to take advantage of solar energy and the ability of nanostructured solar cells fabrication in the country, in this study, the manufacturing problems and complexities of nanostructured solar cells such as dye solar cells and perovskite-based solar cells are investigated. The chromium metal as an alternative to the transparent conductive substrates in order to reduce the manufacturing cost of dye solar cells (DSCs) and reducing series resistance is introduced in this study. In case of utilizing chromium as a substrate for photoanode, the thickness of CrxOy layer is controlled by depositing TiO2 compact layer and the efficiency of DSC is increased from 2.6%... 

    Synthesis and Evaluation of Carbon based Catalyst for HDS Process of Refinery Products

    , Ph.D. Dissertation Sharif University of Technology Hajjar, Zeinab (Author) ; Kazemini, Mohammad (Supervisor) ; Rashidi, Alimorad (Supervisor) ; Bazmi, Mansour (Co-Advisor)
    One of the most important world issues is environmental constraints regarding the pollutants released by transportation fuels and refinery products, sulfur reduction being one of the most significant objectives. Deep hydrodesulfurization processes result in great sulfur reduction in refinery streams. However, such harsh process conditions increase undesired side reactions and facilitate coke formation as well as affecting the surfaces. More effective alternatives for hard process conditions are highly active and selective hydrodesulfurization catalysts, which enable the process to be performed at milder pressure and reaction conditions. Catalyst bases play a very important role in hydrogen... 

    Fabrication and Electrical Characterization of Graphene and Graphene-MOx Hybrid Nanostructures for Gas Sensing Applications

    , Ph.D. Dissertation Sharif University of Technology Esfandiar, Ali (Author) ; Iraji Zad, Azam (Supervisor) ; Akhavan, Omid (Co-Advisor) ; Gholami, Mohammad Reza (Co-Advisor)
    In this project, two types of graphene obtained from chemical and chemical vapor deposition (CVD) methods were studied for gas/vapor sensing applications . In chemical method, oxidation and exfoliation of graphite was performed in liquid phase. AFM, XPS, Raman spectroscopy and Uv-visible spectroscopy were indicated that single layers synthesis of graphene oxide (GO) sheets was formed successfully. Reduction of the GO to reduced graphene oxide (RGO) was chemically done by hydrazine as a conventional reducing agent and melatonin as a green alternative. Photocatalytic reduction and hybridization of GO with TiO2 was also studied. TEM, SEM and AFM analyses confirmed nucleation and growth of TiO2... 

    Investigating Electrochemical Behavior of Biosensor Based on Vertically Aligned Carbon Nanotubes

    , Ph.D. Dissertation Sharif University of Technology Gholizadeh, Azam (Author) ; Shahrokhian, Saeed (Supervisor) ; Iraji Zad, Azam (Co-Advisor) ; Mohajerzadeh, Shamsoddin (Co-Advisor) ; Vossoughi, Manoochehr (Co-Advisor)
    In this research we focus on fabrication, characterization and performance of biosensors based on vertically aligned carbon nanotubes. Carbon nanotubes have been used as high density carbon nanotubes and nanoelectrode array. Carbon nanotubes have been grown using plasma enhanced chemical vapor deposition method. Characterization and performance of biosensors have been studied by cyclic voltammetry and electrochemical impedance spectroscopy methods.
    The mediator-less glutamate biosensor is prepared based on covalently attached glutamate dehydrogenase on vertically aligned carbon nanotubes. The biosensor has a low detection limit of 57 nM, two linear range of 0.1-20 µM with sensitivity of... 

    Synthesis of Graphene by New Methods, and its Application for Adsorption of Cobalt

    , M.Sc. Thesis Sharif University of Technology Faham Mofrad, Ali (Author) ; Outokesh, Mohammad (Supervisor) ; Shafiekhani, Azizollah (Supervisor)
    In this study graphene and graphene adsorbent for the Co2+ ion were created from sodium phenoxide and calcium phenoxide, respectively, using the chemical vapor deposition method, and their chemical, physical, and morphological properties were investigated using FT-IR, UV, XRD, Raman, TEM, FE-SEM, and XPS. The results suggest that the optimum reaction condition for synthesizing mono-layer and multi-layer graphene is the 750 °C temperature for 30 min. The Co2+ adsorbing properties of the synthesized graphene adsorbent from calcium phenoxide was investigated. The investigation of solvation properties suggests insolubility above 650 °C and the kinetic data suggest the rapidness of the Co2+... 

    Feasibility Study of Deposition by SUT-PF

    , M.Sc. Thesis Sharif University of Technology Safarzadehamiri, Ali (Author) ; Vosoughi, Naser (Supervisor)
    Sharif University of Technology Plasma Focus (SUT-PF) is a Mather Type DPF device which has a 39 μF capacitor bank with 14 KV charging ability at its ultimate limit corresponding to 7 KJ stored energy. In the first step of this experiment, a test has been done at three distances 5, 7, 10 cm from anode tip with the different number of shots 20, 30, and 40 at 0 constant angles.In the following, a test is done at 5 and 10 degrees with 40 shots, and PF chamber has been filled up with nitrogen gas. Various tests have carried out for survey of this experiment, the result of which are as follow:The X-ray diffraction (XRD) analysis are used in order to reveal if the Nickel or Nickel nitride have... 

    Electrodeposition of Ni-SiC Nanocomposite Coatings

    , Ph.D. Dissertation Sharif University of Technology Sohrabi Jahromi, Abouzar (Author) ; Dolati, Abolghasem (Supervisor) ; Ghorbani, Mohammad (Co-Advisor)
    In this project Ni-SiC nanocomposite coatings were electrodeposited using Watts nickel bath with addition of SiC particles to the bath. Optimization of Ni-SiC electrodeposition parameters was done using Response Surface Methodology (RSM). At specific conditions, 67 Vol% of 10nm SiC is incorporated in nickel electrodeposits which is unique and not yet reported. Study nanomechanical properties of these coatings using Nanoindentation method, it was realized that the dislocation density is increased as force increasing which is in agreement with increasing intensity of (220) and (200) reflections and intensity attenuation of (111) reflection. Nanoscratch tests show that these... 

    Experimental and Numerical Investigation on Mechanical Properties of Continuous Fiber Reinforced Parts Fabricated with FDM Additive Manufacturing Method

    , M.Sc. Thesis Sharif University of Technology Arjmandi, Mohammad (Author) ; Yousefi, Reza (Supervisor) ; Kouchakzadeh, Mohammad Ali (Supervisor)
    With advancement of science of aircraft design and limitations of traditional manufacturing methods, using new ones in order to improve efficiency is needed. Among those methods to improve structure efficiency are weight reduction or increase in strength. Increasing strength-to-weight ratio and reduction of weight could be achieved by using composite materials and topology optimization respectively. Manufacturing such parts with efficient design using traditional methods is hard or impossible. Additive manufacturing as a new technology which is being developed every day, can be a big help to aerospace industry. Considering the importance of strength-to-weight ratio in aerospace industry and... 

    Computational Simulation of the Effect of Breathing Particle Mass and Breathing Frequency on a Human Respiratory System

    , M.Sc. Thesis Sharif University of Technology Goodarzi Ardakani, Vahid (Author) ; Tayyebi Rahni, Mohammad (Supervisor)
    Our surrounding environment is full of particles with different sizes. These suspended particles enter our body through respiration process, which of course has some negative effects. Therefore, it is very important to comprehend the mechanisms and the effective parameters on these particles motion and their deposition inside the human airway. This work numerically investigates the effects of particles mass and breathing frequency on the deposition of particles in human respiratory system. To this end, a realistic 3-D model of human respiratory system geometry, including nostrils, vestibule, nasal cavity, human sinuses, nasopharynx, oropharynx, larynx, trachea, and main bronchus has been... 

    Financial Contagion ,Interbank Market, and Central Bank Policy

    , M.Sc. Thesis Sharif University of Technology Rashidi Ravari, Pooya (Author) ; Madanizadeh, Ali (Supervisor) ; Mahmoodzadeh, Amineh (Supervisor)
    Financial distress can propagate through different channels such as bank run, deposit interbank market,networks and asset prices. In this paper, with the assumption of deposit insurance, no linkages between banks, no deposit interbank market and fixed asset prices, we show that asset-side shocks might propagate through both loan interbank market and deposit market. However, when there is aggregate liquidity surplus in the banking system, loan interbank market results in the first best allocation. In contrast, aggregate liquidity shortage does not result in optimum allocation. In the presence of deposit and loan interbank market, not only shocks propagate but also they are magnified with the...