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    Investigating the Effects of Different Parameters on Asphaltene Deposition Using Electrodeposition Technique

    , M.Sc. Thesis Sharif University of Technology Hosseini, Ali (Author) ; Ayatollahi, Shahabeddin (Supervisor) ; Taghikhani, Vahid (Supervisor)
    Abstract
    Additional to Temperature, Pressure and Compositional changes of crude oils, Electro-kinetics and Electrical potential effects are also known as the most influencing parameters on Asphaltene deposition during oil production and processing.Mechanisms of electro-kinetics and asphaltene charge generation are very complex and unclear. In the previous studies on asphaltene precipitation and deposition, mostly electro-kinetics effects are ignored.While, recent studies show the great effects of electrical filed on asphaltene deposition during production and processing phase of crude oils.At reservoir porous medium and crude flow line, an electrical field can be developed along the length of the... 

    Modeling of Reactive Flow in Carbonate Rocks with Continuum Approach from Pore Scale to Core Scale

    , M.Sc. Thesis Sharif University of Technology Zarei Darmian, Jamil (Author) ; Ayatollahi, Shahabeddin (Supervisor)
    Abstract
    Carbonate reservoir acidizing is one of the most important well stimulation operations that has been widely used in recent years. Modeling the operation prior to any laboratory tests has always been one of the motivations of scientists in recent years due to the complexity of modeling to consider both mass transfer and reaction phenomena. There are several models have been proposed to simulate the acid injection process in carbonate rocks in recent years, the most important one is the Two-Scale Continuum Model (TSCM). This model utilizes the combination of Darcy-scale transfer and reaction equations and a series of pore scale relations to investigate acid injection into two-dimensional... 

    Modeling of Asphaltene Deposition in Flow Lines Considering Pressure and Temperature Drop

    , M.Sc. Thesis Sharif University of Technology Eyni, Leila (Author) ; Ayatollahi, Shahabeddin (Supervisor) ; Assareh, Mehdi (Supervisor)
    Abstract
    Crude oil is made up of dozens of chemicals which based on their structural similarity, SARA test separate it into four categories: saturates, aromatics, resins and asphaltene. Asphaltenes are recognized as the largest, heaviest and the most polarizable fraction of the crude oil which are in thermodynamic equilibrium with oil at reservoir conditions. Each of the physical, chemical, electrical or mechanical disruption of this balance during production can result in instability and asphaltene precipitation may occur and eventually led to deposition in the reservoir, wells, pipelines, etc. Due to the fact that most changes in temperature and pressure will generated in the wells, thus... 

    The Effect of Fluid Velocity and Rock on Emulsion and Asphaltene Stability in Engineered Salinity Waterflooding

    , Ph.D. Dissertation Sharif University of Technology Balavi, Ali (Author) ; Ayatollahi, Shahabeddin (Supervisor) ; Mahani, Hassan (Supervisor)
    Abstract
    Water-flooding, has been known as one of the most effective techniques to increase oil recovery efficiency. Many studies especially in the past decade have shown that by controlling the amount and type of ions of the injected water the recovery efficiency is significantly improved. It should be noted that inadequate design of flooding operation can disturbed the prevailing balance between the rock and fluids in the reservoir, hence damage the formation. Several different damages are reported such as the formation of unwanted emulsion, mineral and organic material deposition (such as asphaltene) that would affect the operation and hinder the recovery efficiency. Therefore, it is necessary to... 

    Experimental Investigation of Optimum Acid Injection Rate for Matrix Acidizing in Carbonate Reservoir

    , M.Sc. Thesis Sharif University of Technology Ahmadizadeh, Mansour (Author) ; Ayatollahi, Shahabeddin (Supervisor) ; Ghotbi, Sirous (Supervisor)
    Abstract
    Matrix acidizing as a well stimulation technique is performed to increase the production index by increasing the permeability and removing the formation damage in the near wellbore region. However, several challenges such as corrosion of the tubulars and iron precipitation in the formation are hindering this process. To encounter these challenges, different chemicals, or additives, such as corrosion inhibitors and iron control agents are added to the acid solution. Carbonate acidizing has been carried out using HCl-based stimulation fluids for decades. However, at high temperatures, HCl does not produce satisfactory results because of its fast reaction, acid penetration, and hence surface... 

    Investigation of the Effect of Asphaltene on Interfacial Tension Behavior of CO2/Oil Systems during CO2 Injection into Asphaltenic Oil Reservoirs

    , M.Sc. Thesis Sharif University of Technology Mahdavi, Ehsan (Author) ; Taghikhani, Vahid (Supervisor) ; Ayatollahi, Shahabeddin (Supervisor)
    Abstract
    Interfacial Tension (IFT) behavior of crude oil/CO2 system is recognized as the main factor affecting the efficiency of CO2 flooding during enhanced oil recovery (EOR) process. Adding paraffin group hydrocarbon to asphaltenic crude oils as an asphaltene precipitant component is aimed to mimic asphaltene precipitation process during crude oil production and transportation. Asphaltene precipitation would critically effects the IFT behavior of crude oil/CO2 systems. In the first part of this study, the equilibrium densities of oil samples which contain different heptane ratio were measured at different pressures and the temperature of 323 K. Then, the equilibrium IFT between CO2 and the crude... 

    Mathematical Modeling of Diffusion in Fractured Media for Gas Injection

    , M.Sc. Thesis Sharif University of Technology Saki, Mohammad (Author) ; Masihi, Mohsen (Supervisor) ; Shadizadeh, Reza (Supervisor) ; Ayatollahi, Shahabeddin (Co-Advisor)
    Abstract
    It is common to inject gas in naturally fractured reservoirs to maintain the reservoir pressure. Recovery will be the result of the complex interplay of several mechanisms such as viscous flow, extraction by molecular diffusion, gravity drainage, oil swelling and capillary force. Generally the main mechanism is gravity drainage However in many cases like low permeability of matrix, small matrix block size and high capillary pressure; gravity drainage may be very low or ineffective. Low permeability results inefficient viscous displacement too. Therefore in these cases the main mechanism is diffusion. The parameters influences the diffusion are: The nature of the injected gas, the composition... 

    Preparation of Thermosensitive Polymer Nanoparticles to Apply in Smart Enhanced Oil Recovery Process

    , Ph.D. Dissertation Sharif University of Technology Tamsilian, Yousef (Author) ; Ramazani Saadatabadi, Ahmad (Supervisor) ; Ayatollahi, Shahabeddin (Supervisor) ; Masihi, Mohsen (Co-Advisor)
    Abstract
    With the decline in oil discoveries during the last decades, it is believed that enhanced oil recovery (EOR) technologies will play a key role to meet the energy demand in coming years. Polymer flooding has been commonly used worldwide as one of the EOR processes. Literature reviews show that the active water-soluble polymers have a number of limitations related to their surface absorption, undesirable plugging, polymer concentration limitation,expensive, and low thermal, mechanical, bacterial, and salt tolerance. Up to now, five different polymer categories (i.e. polyacrylamide, hydrolyzed polyacrylamide, acrylamidebased resistant copolymers, associative copolymers, and thermoassociative... 

    Monte Carlo simulation of Feynman-α and Rossi-α techniques for calculation of kinetic parameters of Tehran research reactor

    , Article Annals of Nuclear Energy ; Volume 38, Issue 10 , 2011 , Pages 2140-2145 ; 03064549 (ISSN) Hosseini, S. A ; Vosoughi, N ; Hosseini, M ; Sharif University of Technology
    2011
    Abstract
    Noise analysis techniques including Feynman-α (variance-to-mean) and Rossi-α (correlation) have been simulated by MCNP computer code to calculate the prompt neutron decay constant (α0), effective delayed neutron fraction (βeff) and neutron generation time (Λ) in a subcritical condition for the first operating core configuration of Tehran Research Reactor (TRR). The reactor core is considered to be in zero power (reactor power is less than 1 W) in the entire simulation process. The effect of some key parameters such as detector efficiency, detector position and its dead time on the results of simulation has been discussed as well. The results of proposed method in the current study are... 

    Semisolid Stir Joining of AZ91 Magnesium alloy

    , M.Sc. Thesis Sharif University of Technology Abbas Hosseini Niaraki, Vahid (Author) ; Aashuri, Hosseini (Supervisor)
    Abstract
    AZ91 is the most applicable alloy of magnesium alloys.Semisolid stir welding of AZ91 magnesium alloy was investigated due to its welding problem such oxide formation, hot cracking in weld metal, and high residual stress through solidification with special focus on the effect of the welding temperatures, stirring rates, and tool shape. The interlayer with thickness of 2mm was located between two AZ91 pieces with 7.5mm thickness. Then, they were heated to the desired temperatures (515C, 530C and 540C), the semisolid temperature of both base metal and interlayer. A grooved stirrer with six rotational speeds from 0rpm to 2000rpm was introduced into the stir weld seam and the welded coupons... 

    Instagram and its Relation to Moral Values

    , M.Sc. Thesis Sharif University of Technology Hosseini Renani, Niloofar Sadat (Author) ; Hosseini, Hassan (Supervisor)
    Abstract
    In this thesis, the value-ladenness or value-neutrality of technology, new social media and as a result Instagram is investigated. It is also discussed whether values can be taken into account during the design process of technical artefacts, including new social media and Instagram, and methods are developed for this purpose. Several methods have been developed for this purpose, some of them and their compatibility with modern social media are explained; including the Value-Sensitive-Design method and the disclosive computer ethics design method. The frameworks of ethical philosophy such as virtue ethics are reviewed and the appropriate ethical framework for the analysis of new social media... 

    Calculation of fuel burn up and radioactive inventory for HEU fuel element of Tehran Research Reactor

    , Article International Conference on Nuclear Engineering, Proceedings, ICONE, 17 May 2010 through 21 May 2010 ; Volume 2 , 2010 ; 9780791849309 (ISBN) Hosseini, S. A ; Vosoughi, N ; Hosseini, M ; Nuclear Engineering Division ; Sharif University of Technology
    2010
    Abstract
    This paper presents a new approach for fuel burn up evaluation and radioactive inventory calculation used in Tehran Research Reactor. The approach is essentially based upon the utilization of a program written by C# which integrates the cell and core calculation codes, i.e., WIMSD-4 and CITVAP, respectively. Calculation of fuel burn up and radioactive inventories has been done for 26 core configuration of Tehran Research Reactor with HEU fuel element. The present inventory and fuel enrichment of each fuel element have been calculated  

    Preparation and characterization of yttrium iron garnet (YIG) nanocrystalline powders by auto-combustion of nitrate-citrate gel

    , Article Journal of Alloys and Compounds ; Volume 430, Issue 1-2 , 2007 , Pages 339-343 ; 09258388 (ISSN) Hosseini Vajargah, S ; Madaah Hosseini, H. R ; Nemati, Z. A ; Sharif University of Technology
    2007
    Abstract
    The nitrate-citrate gel exhibits auto-catalytic behavior, which can be used to synthesize nanocrystalline YIG powders. In this study, yttrium iron garnet (Y3Fe5O12) nanocrystalline powders were prepared by a sol-gel auto-combustion process. The influence of metal nitrates to citric acid molar ratio (MN/CA) of the precursor solution on the combustion behavior and crystallite size of synthesized powders was investigated by scanning electron microscopy (SEM), thermal analyses (DTA/TGA) and X-ray diffraction (XRD). The results show that with increasing MN/CA value, the combustion rate increases and the single-phase YIG forms at a higher temperature. The crystallite size of the single phase YIG... 

    Experimental and numerical fatigue life study of cracked AL plates reinforced by glass/epoxy composite patches in different stress ratios

    , Article Mechanics Based Design of Structures and Machines ; Volume 49, Issue 6 , 2021 , Pages 894-910 ; 15397734 (ISSN) Hosseini, K ; Safarabadi, M ; Ganjiani, M ; Mohammadi, E ; Hosseini, A ; Sharif University of Technology
    Bellwether Publishing, Ltd  2021
    Abstract
    In this study, the fatigue behavior of composite reinforced cracked aluminum 1050 plates is investigated experimentally and numerically. The tests are conducted in four different stress ratios between 0 and 1. At first step, plates with similar cracks and geometries have been prepared. Then the glass/epoxy patches have been attached to the cracked plates using Araldite 2015 adhesive. Fatigue load has been applied to three cases of samples including non-patch, one-side patch and two-side patch, where in all stress ratios the maximum force is considered constant. A three-dimensional finite element analysis is developed in ABAQUS. A good correlation between finite element results and the... 

    Preparation and characterization of nanocrystalline misch-metal-substituted yttrium iron garnet powder by the sol-gel combustion process

    , Article International Journal of Applied Ceramic Technology ; Volume 5, Issue 5 , 26 August , 2008 , Pages 464-468 ; 1546542X (ISSN) Hosseini Vajargah, S ; Madaah Hosseini, H. R ; Nemati, Z. A ; Sharif University of Technology
    2008
    Abstract
    Nanocrystalline Y3-xMMxFe5O12 powders (MM denotes Misch-metal, x = 0.0, 0.25, 0.5, 0.75, and 1.0) were synthesized by a sol-gel combustion method. Magnetic properties and crystalline structures were investigated using X-ray diffraction (XRD), a vibrating sample magnetometer (VSM), and a scanning electron microscope. The XRD patterns showed that the single-phase garnet of Y3-xMMxFe5O12 was formed at x values ≤ 1.0. The saturation magnetization of powders increased with decreasing MM content and reached the maximum value at Y3 Fe5O12. The crystallite size of powders calcined at 800°C for 3 h was in the range of 38-53 nm. © 2008 American Ceramic Society  

    Synthesis of nanocrystalline yttrium iron garnets by sol-gel combustion process: The influence of pH of precursor solution

    , Article Materials Science and Engineering B: Solid-State Materials for Advanced Technology ; Volume 129, Issue 1-3 , 2006 , Pages 211-215 ; 09215107 (ISSN) Hosseini Vajargah, S ; Madaah Hosseini, H. R ; Nemati, Z. A ; Sharif University of Technology
    2006
    Abstract
    The nitrate-citrate gels exhibit auto-catalytic behavior, which can be used to synthesize the nanocrystalline YIG powders. In this study yttrium iron garnet (Y3Fe5O12) nanocrystalline powders were prepared by a sol-gel auto-combustion process. The influence of pH value of the precursor solution on the combustion behavior and the garnet phase formation of synthesized powders were investigated by scanning electron microscopy (SEM), thermal analysis (DTA/TGA), infrared (IR) spectroscopy and X-ray diffraction technique (XRD). The results show that with increasing pH value, the combustion rate increases. The as-burnt powder prepared with pH 1 yielded a single phase YIG after calcination at 800... 

    L-lysine biodetector based on a TOCNFs-coated Quartz Crystal Microbalance (QCM)

    , Article European Polymer Journal ; Volume 186 , 2023 ; 00143057 (ISSN) Hosseini, M. S ; Iraji zad, A ; Vossoughi, M ; Hosseini, M ; Sharif University of Technology
    Elsevier Ltd  2023
    Abstract
    Developing a simple, cost effective and accurate detection method for L-lysine (Lys), L-leucine (Leu) and glycine (Gly) as the important analytes in clinical diagnostics, biological processes and food industries is of great significance. Herein, we prepared spin-coated TEMPO-oxidized cellulose nanofibrils (TOCNFs) on Quartz Crystal Microbalance (QCM) chip to achieve QCM biodetectors. The coated QCMs were carefully characterized before and after interaction with amino acids (AA) using water contact angle (WCA), Fourier transform infrared spectrophotometry-attenuated total reflectance (FTIR-ATR), Raman spectroscopy, and scanning electron microscopy (SEM). In addition, to study the response of... 

    Lattice Boltzmann simulation of TiO2-water nanofluid in a curved boundary domain at high Rayleigh numbers

    , Article Computers and Fluids ; Volume 168 , 30 May , 2018 , Pages 159-169 ; 00457930 (ISSN) Hosseini Abadshapoori, M ; Saidi, M. H
    Elsevier Ltd  2018
    Abstract
    In this paper, a two-component Lattice Boltzmann Method (LBM) has been utilized to simulate the natural convection of TiO2-water nanofluid in a curved geometry. The main purpose of this research is to study the effect of nanoparticle size and also boundary conditions on the thermal characteristics of the nanofluid. Furthermore, the effect of Rayleigh number (Ra) and volume fraction of nanoparticles (ϕ) on the average Nusselt number (Nuave) have been investigated. Two different thermal boundary conditions, namely adiabatic and constant temperature, have been considered in the current work for the curved boundaries. The Rayleigh number varies from 103 to 109. Four different sizes, namely 10,... 

    High accurate three-dimensional neutron noise simulator based on GFEM with unstructured hexahedral elements

    , Article Nuclear Engineering and Technology ; Volume 51, Issue 6 , 2019 , Pages 1479-1486 ; 17385733 (ISSN) Hosseini, S.A ; Sharif University of Technology
    Korean Nuclear Society  2019
    Abstract
    The purpose of the present study is to develop the 3D static and noise simulator based on Galerkin Finite Element Method (GFEM) using the unstructured hexahedral elements. The 3D, 2G neutron diffusion and noise equations are discretized using the unstructured hexahedral by considering the linear approximation of the shape function in each element. The validation of the static calculation is performed via comparison between calculated results and reported data for the VVER-1000 benchmark problem. A sensitivity analysis of the calculation to the element type (unstructured hexahedral or tetrahedron elements) is done. Finally, the neutron noise calculation is performed for the neutron noise... 

    Neutron spectrum unfolding using artificial neural network and modified least square method

    , Article Radiation Physics and Chemistry ; Volume 126 , 2016 , Pages 75-84 ; 0969806X (ISSN) Hosseini, S. A ; Sharif University of Technology
    Elsevier Ltd  2016
    Abstract
    In the present paper, neutron spectrum is reconstructed using the Artificial Neural Network (ANN) and Modified Least Square (MLSQR) methods. The detector's response (pulse height distribution) as a required data for unfolding of energy spectrum is calculated using the developed MCNPX-ESUT computational code (MCNPX-Energy engineering of Sharif University of Technology). Unlike the usual methods that apply inversion procedures to unfold the energy spectrum from the Fredholm integral equation, the MLSQR method uses the direct procedure. Since liquid organic scintillators like NE-213 are well suited and routinely used for spectrometry of neutron sources, the neutron pulse height distribution is...