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    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)
    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... 

    Dynamic Modeling and Experimental Study of Asphaltene Deposition in Wellbore Considering Mechanism of Precipitation, Aggregation and Deposition

    , Ph.D. Dissertation Sharif University of Technology Salehzadeh, Marziyeh (Author) ; Ghotbi, Cyrus (Supervisor) ; Dabir, Bahram (Co-Supervisor) ; Taghikhani, Vahid (Co-Supervisor)
    Efforts to identify, predict, and resolve problems linked to asphaltenes and flow assurance have resulted in the development of numerous laboratory and modelling techniques. However, there has been little research on the molecular structure of asphaltenes and how it relates to solubility, stability, aggregation, and deposition behavior. Not only was a thorough structural analysis of asphaltene extracted from three samples of light, medium, and heavy oil performed in this study, but medium oil asphaltene was also fractionated into three sub-fractions based on solubility, with minimum, medium, and maximum solubility, and each subfraction was subjected to a structural analysis. All asphaltene... 

    Design and Optimization of RSFQ Based Digital SQUID for High Sensitive Measurement of Widely Varying Magnetic Fields

    , Ph.D. Dissertation Sharif University of Technology Foroughi, Farshad (Author) ; Fardmanesh, Mehdi (Supervisor)
    Analog SQUIDs have limited slew rate and dynamic range and these problems make it hard to operate SQUID systems in unshielded applications like Bio-magnetic imaging and NDE. Recently by combining analog SQUIDs and RSFQ Logic, new class of magnetic sensors are introduced. These sensors have an acceptable sensitivity and very high dynamic range. On the other hand these sensors, Which are called Digital SQUIDs, can be directly connected to digital signal processing stages. In This work, for first time, a digital SQUID completely based on i-directional RSFQ was designed and optimized. using Bi-directional RSFQ, one can significantly simplify the digital SQUID circuit design and therefore... 

    Synthesis and Characterization of Cu2ZnSnS4 (CZTS)Thin Films Prepared by Pulsed Laser Deposition Technique

    , M.Sc. Thesis Sharif University of Technology Dabbagh, Mohammad Mahdi (Author) ; Mahdavi, Mohammad (Supervisor)
    The Cu2ZnSnS4 (CZTS) quaternary compound, with suitable optical and electrical properties, is one of the most interesting materials for absorber layer of thin film solar cell. Since all constituents of CZTS, are abundant in earth’s crust and non-toxic, it is a proper replacement for the materials like CdTe and CuInSe2. The CZTS pellet was synthesized by the solid-state reaction and deposited on soda lime glass substrates by pulsed laser deposition (PLD) method. PLD technique has the advantages of offering stoichiometric preservation during the materials transformation from target to substrate and good crystallinity due to the highly energetic species. CZTS has was deposited in order to... 

    Deposition and Analysis of Indium-Tin-Oxide NanoStructures Using Sputtering

    , M.Sc. Thesis Sharif University of Technology Bagheri, Behrang (Author) ; Rashidian, Bijan (Supervisor)
    Transparent conductive materials have been widely used in semiconductor technology. Among them all, Indium tin oxide (ITO) has been utilized as electrodes in liquid crystal displays, solar cells, heat reflecting films and gas sensors.In general, the desired properties of transparent conductive oxides are high conductance and transmission. However, due to the complexity of ITO molecular structure, the film properties strongly depend on the depositon parameters.In first part of this thesis, physical properties and electrical characteristic of ITO films, different deposition techniques, and effects of deposition parameters (substrate temperature, pressure, power, etc. ) on film properties are... 

    Fabrication and Investigation of Printing Mechanism in order to Deposit Semiconductor thin Films for Photovoltaic Devices

    , M.Sc. Thesis Sharif University of Technology Akbari, Hamid Reza (Author) ; Taghavinia, Nima (Supervisor)
    Finding a reliable and reproducible method to deposit thin films of semiconductors is a huge leap forward in order to fabricate nano-structured solar cells. As the third and forth generation of solar cells are based on semiconductors which are soluble in solvents and can be deposited with solution-based methods, finding a proper printing mechanics can lead to cheap solar panels. In this thesis we have designed and fabricated an apparatus to deposit lead iodide films. These thin films can be used to fabricate perovskite solar cells which are based on methylammonium lead iodide perovskite. We have also investigated different inks consisting of different additives and solvents best suited for... 

    Development of Printing Methods for Fabrication of Perovskite Solar Cells

    , M.Sc. Thesis Sharif University of Technology Shabanzade, Mostafa (Author) ; Taghavinia, Nima (Supervisor)
    The highest efficiency of Perovskite solar cells that is attained up to now, is around 24%. This champion solar cell is prepared under vacuum. This method suffers from low rapidity, small deposition area and high cost which are not compatible with commercialization. Printing method has a special position in mass production of electronic equipment, such as solar cells. This method has the potential of high rapid, low cast and repeatable deposition. In this thesis, I introduce a novel deposition method, named Capillary Adhesion Coating, which is based on capillary concept. The novel deposition method coats infinite perfect thinfilms with high rapidity and low cost. After the introducing of... 

    Investigation of Application of Nano-Photocatalytic Degradation for Industrial Wastewater Treatmen

    , M.Sc. Thesis Sharif University of Technology Falahati, Mohammad (Author) ; Roosta Azad, Reza (Supervisor) ; Vossoughi, Manouchehr (Supervisor)
    The main objective of this project is the deposition of photo-catalysts on cement and concrete blocks with an emphasis on commercialization. We started with an extensive study of common methods introduced in previous literature, and conclude with a number of suggestions for industrialization. First, slurry and sol-gel deposition of the photo-catalysts on blocks of type 2 commercial cement which is one of the most used materials in construction of buildings and waste-water treatment plants has been examined to reach a method of sample formation. Due to the simplicity of common methods and low quality of formed samples (less than 5 percent aging efficiency), the obtained experience was used to... 

    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... 

    Investigating the Effect of Asphaltene Flocculation Size on Deposition

    , M.Sc. Thesis Sharif University of Technology Razghandi, Milad (Author) ; Ghotbi, Siros (Supervisor) ; Ayatollahi, Shahabodin (Supervisor) ; Dabir, Bahram (Co-Advisor)
    Asphaltene precipitation and deposition are sources of a number of problems for petroleum industry. Thus, solving the problem of precipitation and deposition is very important. In order to measure deposition level, study of other asphaltene flocculation is vital; since there is a time interval between precipitation and deposition. Use of chemical inhibitors is one of the best methods for prevention of asphaltene precipitation that could postpone precipitation point and prevent formation of huge flocculations. In this study, effects of asphaltene flocculation size on deposition with or without using inhibitors were investigated. In this regard, QCM was used for measuring the amount of... 

    Experimental Investigation of Asphaltene Precipitation and Deposition in Enhanced Oil Recovery by Low Salinity Waterflooding

    , M.Sc. Thesis Sharif University of Technology Hosseini, Ali (Author) ; Ayatollahi, Shahabadin (Supervisor) ; Fatemi, Mobin (Supervisor)
    Asphaltenes are a polydisperse mixture of the heaviest and most polarizable fractions of the crude oil. They are defined according to their solubility properties as being soluble in aromatic solvents but insoluble in light paraffin solvents. Asphaltenes are usually responsible for many problems like wettability changes of the reservoir rock, pore clogging in the reservoir porous matrix and fouling in wellbore tubing and production surface facilities. Most of the studies in the literature, addressing the asphaltene precipitation and deposition (APD), are investigating natural depletion or gas injection process such as CO2 flooding. These studies show that asphaltene deposition and...