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Modeling Multiphase Fluid Flow Using SPH
, M.Sc. Thesis Sharif University of Technology ; Taghizadeh Manzari, Mehrdad (Supervisor)
Abstract
Smoothed Particle Hydrodynamics (SPH) is a Lagrangian method for simulation of fluid flow. Movable particles are used to interpolate fluid properties instead of fixed Eulerian grids in this method. By essence, the aforesaid particles are movable points which carry the fluid properties such as temperature, enthalpy, density, etc. these variables can also be the stress, strain or the rheological properties of the fluid. Thus, this method needs no grids and the fluid properties are calculated using an interpolation mechanism which classifies this method as meshless. A computational code is designed using SPH for the simulation of multiphase flows. Usage of the Lagrangian formulation has made it...
Investigation of Flow Rate and Cooling Water Temperature Effects on the Process Parameters in Centrifuge Machine
, M.Sc. Thesis Sharif University of Technology ; Otukesh, Mohammad (Supervisor) ; Safdari, Jaber (Supervisor)
Abstract
Centrifuge is a method in which great gravitational-like forces are used. Gravitational forces which cause molecules to move and are relevant to molecular weight; can cause isotope separation. The separation of light isotope from heavy one is done with a centrifugal field which produces a pressure gradient for the gas mixture. Pressure gradient is different for each of the isotopes due to the dependence of pressure gradient to the mass of the materials. But the separation in this way is very limited. The capacity of separation can be brought up by producing an additional axial flow in the rotor. This rotational flow can be produced with internal or external incitement. Rotational flow with...
A Study of Practical Methods for Petroleum Hydrocarbons Removal from Polluted Groundwaters in a Refinery
, M.Sc. Thesis Sharif University of Technology ; Kariminia, Hamid Reza (Supervisor)
Abstract
Petroleum based products are the major sources of energy for industry and daily life, With the development of social economy, the demands of the oil have increased dramatically. Petroleum hydrocarbons can cause environmental pollution during various stages of production, transportation, refining and use. Releases of petroleum products(e.g., gasoline, diesel, fuel oil) from aboveground and underground storage tanks or transport pipelines are the major causes of the environment pollution.The major constituents of petroleum hydrocarbons are biodegradable. Many soil microorganisms transform oil hydrocarbons into nontoxic compounds or mineralize them to inorganic compounds. In situ...
Adsorption of pollutant cations from their aqueous solutions on graphitic carbon nitride explored by density functional theory
, Article Journal of Molecular Liquids ; Volume 260 , 15 June , 2018 , Pages 423-435 ; 01677322 (ISSN) ; Shamkhali, A. N ; Tafazzoli, M ; Parsafar, G ; Sharif University of Technology
Elsevier B.V
2018
Abstract
In this study, adsorption of important pollutant cations on the surface of graphitic carbon nitride (g-C3N4) was investigated by density functional theory. The calculations indicated that N6 cavity surrounded by triazine units is the most probable adsorption site on this surface. The structural optimizations also predicted a planar surface for Cr3+, and Ni2+/g-C3N4 systems while the structure of the surface for other systems indicated a considerable distortion with strong dependency on the cation size. Also, g-C3N4 surface exhibited the high adsorption energies for Cr3+, As3+, and Sb3+ ions in the gas phase. However, formation energies of the metal-aquo complexes of these cations indicated...
Teichmüller Spaces and Grothendieck’s Dessins
, M.Sc. Thesis Sharif University of Technology ; Safdari, Mohammad (Supervisor) ; Kamalinejad, Ali (Supervisor)
Abstract
The main goal of this thesis is to study the Teichmüller space and its geometric properties. The Teichmüller space of a surface can be studied from complex geometric or hyperbolic geometric points of view, and in this thesis we refer to both of these viewpoints where needed. Another goal of this thesis is to review a method of compactification of the Teichmüller space. Therefore, we introduce the compactification method proposed by Thurston. To this end, we first briefly review hyperbolic geometry. Then we extend some tools, and use some techniques in hyperbolic geometry, to describe Thurston’s construction and pave the way for it. In the second phase of this study, we introduce...
Development of bioreactors for comparative study of natural attenuation, biostimulation, and bioaugmentation of petroleum-hydrocarbon contaminated soil
, Article Journal of Hazardous Materials ; Volume 342 , 2018 , Pages 270-278 ; 03043894 (ISSN) ; Kariminia, H. R ; Rahmati, M ; Fazlollahi, F ; Polasko, A ; Mahendra, S ; Wilding, W. V ; Fletcher, T. H ; Sharif University of Technology
Elsevier B.V
2018
Abstract
Bioremediation of soil and groundwater sites contaminated by petroleum hydrocarbons is known as a technically viable, cost-effective, and environmentally sustainable technology. The purpose of this study is to investigate laboratory-scale bioremediation of petroleum-hydrocarbon contaminated soil through development of eight bioreactors, two bioreactors for each bioremediation mode. The modes were: (1) natural attenuation (NA); (2) biostimulation (BS) with oxygen and nutrients; (3) bioaugmentation (BA) with hydrocarbon degrading isolates; (4) a combination of biostimulation and bioaugmentation (BS-BA). Total petroleum hydrocarbons (TPH) mass balance over the bioreactors showed about 2% of...
Uranium Bioleaching from a Low Grade Ore
,
Ph.D. Dissertation
Sharif University of Technology
;
Roosta Azad, Reza
(Supervisor)
;
Safdari, Jaber
(Supervisor)
Abstract
In this work, bioleaching was used to extract valuable uranium from a low grade ore. Bioleaching experiments were carried out in batch cultures using a native strain of Acidithiobacillus ferrooxidans. Experiments were conducted to investigate the effects of rotation speed, initial redox potential, initially added Fe concentration, particle size, pH, temperature, pulp density, and culture type. In the shake flask systems, over 99% of the uranium was bioleached in 48 hours at some conditions. Uninoculated flasks gave only around 25% leaching. At each study, uranium and iron concentrations, solution oxidation– reduction potential and pH were measured. The results showed that 150 rpm, d80=100 ...
Theoritical Investigation of Metallic Cations and Gas Adsorption on Surface of Carbon Nanostructures
, Ph.D. Dissertation Sharif University of Technology ; Tafazoli, Mohsen (Supervisor) ; Shamkhali, Amir Nasser (Supervisor)
Abstract
Carbon nanostructures are of great importance in scientific and industrial research. Two case of the important two-dimensional carbon nanostructures are graphitic carbon nitride (g-C3N4) and graphene. In the first part of this work, adsorption of important heavy metal cations including Hg+2, Ag+, Cr+3, Pb+2, Cu+2, Ni+2, Cd+2, Tl+, Sb+3, Zn+2 and As+3 on the surface of (g-C3N4) was investigated by density functional theory (DFT). The main purpose of this theoretical study is to evaluate the ability of g-C3N4 to adsorb pollutant cations. The most prominent result of this work was the ability of g-C3N4 for effective adsorption of As+3 and Sb+3 ions from aqeous solutions. Also, another...
Mechanistically Investigation of Residual Oil Saturation in Heterogeneous Glass Micromodel during Low Salinity Water Injection
, M.Sc. Thesis Sharif University of Technology ; Ayatollahi, Shahaboddin (Supervisor) ; Masihi, Mohsen (Supervisor)
Abstract
Oil and gas reservoirs in various parts of the world have declined over time, despite a high percentage of oil. Due to the increasing need for hydrocarbon resources, the need for more cost-efficient harvesting methods and less environmental damage is felt. Injection of saline water is one of the most cost-effective ways of harvesting due to the need for no expensive additives. On the other hand, microscopic glass modeling can be used to better understand and understand the performance of saline water at the microscopic scale. In this study we have been able to visualize the effective factors in infusion of saline water. Improved interfacial tensile and particle migration in kaolin-coated...
Classification of Partial Hyperbolic Diffeomorphisms on 3-manifolds
, M.Sc. Thesis Sharif University of Technology ; Safdari, Mohammad (Supervisor) ; Nassiri, Meysam (Supervisor)
Abstract
In this dissertation, we will study partially hyperbolic diffeomorphisms. First, we are going to introduce partially hyperbolic diffeomorphisms and construct some examples. One of the important questions in the study of partially hyperbolic diffeomorphisms is their classification problem, which provides a deeper understanding of manifolds and also of partially hyperbolic diffeomorphisms themselves. We will go through this problem by examining Hammerlindl, Potrie’s [1]’s work. They have proved that a partially hyperbolic diffeomorphism on a 3-manifold with a virtually solvable fundamental group, that has no periodic torus tangent to contraction-center or expansion-center, is dynamically...
A Detailed Study on Extraction of Uranium from Mother Leach Liquor (of Uranium Mills) by TOA Extractant and Development of a Thermodynamical Model for it
, M.Sc. Thesis Sharif University of Technology ; Samadfam, Mohammad (Supervisor) ; Safdari, Jaber (Supervisor) ; Mallah, Hassan (Co-Advisor)
Abstract
In many uranium mines such as gachin-bandarabbas, sulfuric acid is used for leaching operation on ore after crushing operation. This leach liquor, containing uranium, is extracted by specific solvent, including extractant like TOA. However, this operation, named Amex, have been used for many years, there is a vacancy for a detailed thermodynamical studying on uranium extraction from leach liquor.To have a thermodynamical model, we need information about the equilibrium concentration of all the components that may have effect on uranium extraction and also concentration of solvent, pH, phase ratio and activity coefficient alteration. This model must have the ability to predict the equilibrium...
Study potential of indigenous pseudomonas aeruginosa and bacillus subtilis in bioremediation of diesel-contaminated water
, Article Water, Air, and Soil Pollution ; Volume 228, Issue 1 , 2017 ; 00496979 (ISSN) ; Kariminia, H. R ; Ghobadi Nejad, Z ; Fletcher, T. H ; Sharif University of Technology
2017
Abstract
Petroleum products which are used in a wide variety of industries as energy sources and raw materials have become a major concern in pollution of terrestrial and marine environments. The purpose of this study was to assess the potential of indigenous microbial isolates for degradation of diesel fuel. Two most proficient bacterial strains among five isolated strains from polluted soil of an industrial refinery were studied. The isolates then were identified as Pseudomonas aeruginosa and Bacillus subtilis using biochemical tests and 16S rRNA gene sequence analyses. P. aeruginosa showed higher biodegradation efficiency than B. subtilis in shaking flask containing diesel-contaminated water. P....
Municipal wastewater treatment by semi-continuous and membrane algal-bacterial photo-bioreactors
, Article Journal of Water Process Engineering ; Volume 36 , 2020 ; Babaei, A ; Mehrnia, M. R ; Shayegan, J ; Safdari, M. S ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Conventional wastewater treatment systems demand a high cost mechanical aeration. Using algal-bacterial systems helps to reach a cost-efficient treatment method by eliminating mechanical aeration, since algae produce the oxygen needed for treatment process. In this study, two groups of experiments were performed for domestic wastewater treatment processes. For the first group, semi-continuous microalgae-bacterial photo-bioreactors were cultivated. Chlorella Vulgaris and activated sludge (AS) were used as microalgae and bacterial inoculums, respectively. The effect of different algae and AS ratios on the chemical oxygen demand (COD), N-NH4 + and P-PO4 3− removal was studied. The removal...
Study of Effects of Operational Parameters on Flooding in Pertraction of Dysprosium in a Vertical Pulsed Packed Column
, M.Sc. Thesis Sharif University of Technology ; Bastani, Dariush (Supervisor) ; Safdari, Jaber (Supervisor) ; Raji, Maliheh (Co-Supervisor)
Abstract
Pulsed packed columns are among the most important devices used in liquid-liquid extraction, with wide application in petroleum and petrochemical industries, metal salt extraction, pharmaceutical industries, metallurgy, and other areas. Liquid-membrane technology is an alternative separation technique to the liquid-liquid extraction for the extraction and recovery of metal ions from aqueous solutions. There are three main types of liquid membranes: emulsion liquid membrane (ELM), Bulk Liquid Membrane (BLM), and Supported Liquid Membrane (SLM). Liquid emulsion membrane is one of the pertraction methods with phase dispersion. It is a three-phase dispersion system, consisting: external phase,...
, M.Sc. Thesis Sharif University of Technology ; Samadfam, Mohammad (Supervisor) ; Mallah, Mohammad Hassan (Supervisor) ; Safdari, Jaber (Supervisor)
Abstract
In many uranium mines such as gachin-bandarabbas, use sulfuric acid for leaching operation on ore. This leach liquor, containing uranium, is extracted by organic solvent, such as D2EHPA (dapex process ).althogh this process have being used for many years, there is a vacancy for detailed thermodynamical studying on uranium extraction of uranium from leach liquor. To have a thermodynamical model, we need information on equilibrium concentration of all component that may have effect on uranium extraction in addition we need concentration of solvent , pH, phase ratio and activity coefficient.such a model must have the ability to predict the equilibrium concentration in alloperation condition....
Bioleaching of Vanadium from Multimetal Ore of Saghand Mine
, M.Sc. Thesis Sharif University of Technology ; Roosta Azad, Reza (Supervisor) ; Safdari, Jaber (Supervisor) ; Firouzzare, Mohammad Ali (Co-Advisor)
Abstract
In this work bioleaching of vanadium has been done from Saghand Ore (Anomaly II). Leaching of vanadium was done in several stages. First, Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxxidans were used for dissolution of pure vanadium pentoxide and it was observed that these bacteria are able to dissolve and reduce vanadium with high efficiency. After that these bacteria were employed to leaching of vanadium from ore; however there were no results by those experiments and no vanadium dissolved in liquor although bacterial activity was visible. In the second stage, oxalic acid 0.1 M as an organic acid and three inorganic acids, namely sulfuric, hydrochloridric and nitric acids, in...
Effect of heating profile on desorption curve in temperature programmed desorption analysis: Case study of acid sites distribution of SAPO-34
, Article Journal of Porous Materials ; Volume 16, Issue 5 , 2009 , Pages 599-603 ; 13802224 (ISSN) ; Farhadi, F ; Khorasheh, F ; Yan, Z. F ; Sharif University of Technology
2009
Abstract
Comparison of the traditional linear heating method of TPD with an original stepwise heating scheme was reported for the first time. Stepwise heating TPD was carried out by keeping the temperature constant as soon as ammonia desorption signal rises until the signal returns to the baseline. More ammonia desorption peaks on a SAPO-34 catalyst were identified using TPD with stepwise heating. The effect of temperature ramp on desorption peak broadening in TPD curve was also addressed. The more distinct ammonia desorption peaks in stepwise TPD indicates that ammonia adsorbs in about five or six different ways on SAPO-34, and attribution of different adsorptions may be explained considering some...
Theoretical and experimental study of cascade solar stills
, Article Solar Energy ; Volume 90 , April , 2013 , Pages 205-211 ; 0038092X (ISSN) ; Sharak, A. Z ; Moghadam, H ; Tabrizi, F. F ; Sharif University of Technology
2013
Abstract
Most part of Iran is dominated by arid and semi-arid areas due to low annual rainfall. The need for production of fresh water from brackish water is considerably high, especially in dry regions. In this study 1 month daily-based experimental data from a solar still site has been reported. The technical and operational problems of this site which finally contributed to the total cease of the site are described. Then a detailed analysis is investigated on progress of a prototype which constructed in order to solve the site's problems. The results of 1 month of experimental data of the final design showed that the last prototype could be used to solve the current problems of the site. The...
Application of a continuous kinetic model for the hydrocracking of vacuum gas oil
, Article Petroleum Science and Technology ; Vol. 32, Issue. 18 , 2014 , Pages 2245-2252 ; ISSN: 10916466 ; Khorasheh, F ; Farhadi, F ; Sharif University of Technology
2014
Abstract
Hydrocracking is one of the most versatile petroleum refining processes for production of valuable products including gasoline, gas oil, and jet fuel. In this paper, a five-parameter continuous lumping model was used for kinetic modeling of hydrocracking of vacuum gas oil (VGO). The model parameters were estimated from industrial data obtained from a fixed bed reactor operating at an average temperature of 400°C and residence time of 0.3 h. Product distributions were obtained in terms of the weight fraction of various boiling point cuts. The model parameters were estimated using the Nelder-Mead optimization procedure and were correlated with temperature. Comparison of experimental and...
An improved methodology for design of custom-made hip prostheses to be fabricated using additive manufacturing technologies
, Article Rapid Prototyping Journal ; Volume 18, Issue 5 , 2012 , Pages 389-400 ; 13552546 (ISSN) ; Abbaszadeh, F ; Farahmand, F ; Sharif University of Technology
Emerald
2012
Abstract
Purpose - The purpose of this paper is to present an improved methodology for design of custom-made hip prostheses, through integration of advanced image processing, computer aided design (CAD) and additive manufacturing (AM) technologies. Design/methodology/approach - The proposed methodology for design of custom-made hip prostheses is based on an independent design criterion for each of the intra-medullary and extra-medullary portions of the prosthesis. The intra-medullar part of the prosthesis is designed using a more accurate and detailed description of the 3D geometry of the femoral intra-medullary cavity, including the septum calcar ridge, so that an improved fill and fit performance...