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hajizadeh--alireza
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Simulation of 2-Phase Fluid Flow on Unstructured Grids Upscaled by Image Segmentation Methods
, M.Sc. Thesis Sharif University of Technology ; Jamshidi, Saeed (Supervisor) ; Hajizadeh, Alireza (Co-Advisor)
Abstract
This paper describes the use of Quad-Tree Decomposition for upscaling of absolute permeability 2D geological models. Quad-Tree Decomposition is a data structure and generates an unstructured upscaled model that preserves the heterogeneity of the original geological model. In other words, in high-variability regions of the geological model, the gridblocks of the upscaled model remain small but in other regions that the permeability variation is low, the gridblocks of the upscaled model are coarsened. Quad-Tree Decomposition is a very simple, efficient and robust method that reduces the total number of gridblocks and results to high saving in time and memory required to flow simulation in the...
Observer-Based Output Feedback Linearization Control with Application to HIV Dynamics
, Article Industrial and Engineering Chemistry Research ; Volume 54, Issue 10 , January , 2015 , Pages 2697-2708 ; 08885885 (ISSN) ; Shahrokhi, M ; Sharif University of Technology
American Chemical Society
2015
Abstract
This paper presents the feedback linearization control of HIV infection. A multi-input multi-output (MIMO) dynamic nonlinear HIV infection model for this purpose has been used. For this purpose, three widely used drugs are considered. A Luenberger-like nonlinear observer (LNO) is designed for estimation of unavailable states. To minimize the side effects of drugs, the concentration of ZDV which has the highest side effect is fixed to a minimum value and the external controllers parameters are obtained by maximizing an objective function. In the control design, limitations on drug consumption and unavailability of all states are taken into account. The closed-loop stability has been...
Dynamic Simulation of HIV Infection and Its Control
,
M.Sc. Thesis
Sharif University of Technology
;
Shahrokhi, Mohammad
(Supervisor)
Abstract
This project presents appropriate strategies for HIV infection treatment. In order to close the presented strategy to real treatment regimen, appropriate parameters are selected for the HIV infection model, real outputs are considered for the system, and three widely used drugs (one PI: ritonavir (RDV), two RTIs: lamivudine (3TC) and zidovudine (ZDV)) are used to design a drug regimen. A Luenberger-like nonlinear observer (LNO) is also designed for estimation of unmeasurable states. In order to minimize the side effects of drug regimen, the concentration of ZDV is fixed at a minimum value at all time because this drug has a greater side effects than other drugs and the parameters of...
Quad-Tree decomposition method for areal upscaling of heterogeneous reservoirs: Application to arbitrary shaped reservoirs
, Article Fuel ; Volume 139 , 2014 , Pages 659-670 ; 00162361 (ISSN) ; Jamshidi, S ; Hajizadeh, A ; Sharif University of Technology
2014
Abstract
In this paper, Quad-Tree decomposition method is applied for areal upscaling of irregular shaped petroleum reservoirs. Quad-Tree decomposition is a recursive data structuring technique which generates an upscaled model with non-uniform (unstructured) gridblocks. This type of coarsening reduces the number of gridblocks, but preserves the main heterogeneity features of the original fine model. Because of the quadruplet nature of the Quad-Tree decomposition, this method cannot be used for upscaling of irregular-shaped models, directly. In this study, by circumscribing a square to the irregular-shaped reservoirs, a temporary model is obtained which can be upscaled by Quad-Tree decomposition....
Evaluation of planing craft maneuverability using mathematical modelling
, Article Brodogradnja ; Volume 67, Issue 1 , 2016 , Pages 85-100 ; 0007215X (ISSN) ; Seif, M.S ; Mehdigholi, H ; Sharif University of Technology
Brodarski Institute
2016
Abstract
Ship transportation is increasing globally as is the risk of collision especially in congested areas. Numerical modeling method is a major simulation method to predict ship maneuverability. Ship maneuvering in calm water is an important topic to avoid collisions and leads to safe navigation. Therefore, reliable ship maneuvering simulations are required for incident analysis and prevention. In recent time within the research community orientated towards ship hydrodynamics an increasing attention has been paid to simultaneous solution of the planing ship maneuvering problem. The maneuverability of planing craft has been the subject of many research projects during the last few decades. To...
Separation and Purification of Conjugated Linoleic Acid Isomers from Vegetable Oils
, M.Sc. Thesis Sharif University of Technology ; Alemzadeh, Iran (Supervisor)
Abstract
Conjugated linoleic acid (CLA), a mixture of positional and geometrical isomers of linoleic acid with conjugated double bonds, has gained considerable attention because of its anticarcinogenic and obesity treatment properties. The most biologically active CLA isomers are 9c, 11t-18:2 and 10t, 12c-18:2. The aim of this study is to separate and purify the two essential isomers via enzymatic method by Candida rugosa lipase and chemical method by urea crystallization and also optimization of reaction conditions in order to better separation. For enzymatic purification, L-menthol and Lauryl alcohol were used separately. Optimization of reaction conditions by enzyme content, time and the ratio of...
Enhanced Superhydrophobic and Photocatalytic Characteristics of Tio2 Hybrid Nanocoating for Self-cleaning Applications
, M.Sc. Thesis Sharif University of Technology ; Mohammadi, Mohammad Reza (Supervisor)
Abstract
Many researches have been made on super hydrophobic and photocatalyst nano coatings in the last decades as a solution to some environmental issues. Among all semiconductors chosen for this property, titanium dioxide is often used because of it's low cost, ease of accessibility and stability in different chemical circumstances to break up organic pollutions. Mixing this property of TiO2 with hydrophobic manner of SiO2 causes a superhydrophobe & photocatalyst nano coating. Doping TiO2 with another semiconductor may also improve photocatalytic behavior of coating by increasing surface area of reaction or decreasing the band-gap.In this research TiO2-SiO2 hybrid nano coating is made via...
A multiple-point statistics algorithm for 3D pore space reconstruction from 2D images
, Article Advances in Water Resources ; Volume 34, Issue 10 , October , 2011 , Pages 1256-1267 ; 03091708 (ISSN) ; Safekordi, A ; Farhadpour, F. A ; Sharif University of Technology
2011
Abstract
Fluid flow behavior in a porous medium is a function of the geometry and topology of its pore space. The construction of a three dimensional pore space model of a porous medium is therefore an important first step in characterizing the medium and predicting its flow properties. A stochastic technique for reconstruction of the 3D pore structure of unstructured random porous media from a 2D thin section training image is presented. The proposed technique relies on successive 2D multiple point statistics simulations coupled to a multi-scale conditioning data extraction procedure. The Single Normal Equation Simulation Algorithm (SNESIM), originally developed as a tool for reproduction of...
Effect of Grain Refining, Cooling Rate and Modification on Shrinkage Porosities in A356 Aluminum Alloy
, M.Sc. Thesis Sharif University of Technology ; Varahram, Naser (Supervisor)
Abstract
In this study, the influence of eutectic modification, grain refining and cooling rate on amount of shrinkage porosity in aluminium A356 alloy were investigated. Modification process for changing the morphology of eutectic silicon from needle like to fibrous like, use in aluminium – silicon alloys. This process often leads to increasing porosity in melt and affect harmfully on mechanical properties. For studying shrinkage porosity, the melt degassed completely to minimizing amount of gas in the melt. For modification, strontium in Al-10Sr master alloy and sodium in NaF salt used and for grain refining Al-10Ti and Al-5Ti-1B master alloys used. To study the effect of cooling rate, three mold...
Determination of ship maneuvering hydrodynamic coefficients using system identification technique based on free-running model test
, Article Scientia Iranica ; Volume 23, Issue 5 , 2016 , Pages 2154-2165 ; 10263098 (ISSN) ; Seif, M. S ; Mehdigholi, H ; Sharif University of Technology
Sharif University of Technology
2016
Abstract
In the recent years, different mathematical models have been suggested for maneuvering of displacement vessels that are capable of estimation of vessel maneuvers with acceptable precision. These mathematical models are based on determined hydrodynamic coefficients and their accuracy depends on the known coefficients used to solve the mathematical model. System identification methods are developed to calculate these coefficients utilizing input and output data obtained from different sources. In this research, a 4.36-m model of KRISO Container Ship (KCS) displacement vessel has been manufactured by fiberglass, and the maneuver turning tests have been carried by self-propulsion method. A...
Evaluation of planing craft maneuverability using mathematical modeling under the action of the rudder
, Article Scientia Iranica ; Volume 24, Issue 1 , 2017 , Pages 293-301 ; 10263098 (ISSN) ; Seif, M. S ; Mehdigholi, H ; Sharif University of Technology
Sharif University of Technology
2017
Abstract
In the recent years, different mathematical models have been suggested for maneuvering of displacement vessels, which are capable to estimate maneuvering of the vessel with acceptable precision. But, simulation of planing craft maneuverability through a mathematical model has not been developed yet. In this paper, a mathematical model is developed for maneuvering of the planing craft by including the rudder forces and moments. Different maneuvers, such as straight-line stability, course keeping, and turning circle, are executed through the mathematical model. Simulation results are validated with the published experimental results and it is shown that they are in good agreement. Finally, the...
Capital Structure Impact on the Performance of Listed Companies in the Tehran Stock Exchange
, M.Sc. Thesis Sharif University of Technology ; Hajizadeh, Iman (Supervisor)
Abstract
This thesis analyses the relationship between performance and capital structure of listed companies in the Tehran stock exchange. For examining this relationship, we use trade-off theory. This theory states that using debt comes with some benefits and costs for the company. If this theory holds true, we expect that in a low debt capital structure, as a result of benefits of using debt surpasses the costs of it, the relationship between debt and performance should be positive and in a high debt capital structure, as a result of costs of using debt surpasses the benefits of it, using more debt should have negative relationship with performance. For examining this relationship, we first gather...
Forward Temporal Planning Using Time Abstraction
, M.Sc. Thesis Sharif University of Technology ; GhassemSani, Gholamreza (Supervisor)
Abstract
Successful performance of forward heuristic planners in classical planning, has motivated the use of forward heuristic search in many temporal planners. Most of forward temporal planners are decision epoch planners that use an explicit representation of time and schedule actions while searching. However, decision epoch planners aren’t complete and cannot solve certain temporal problems with required concurrency. In this dissertation, we present ATFP, a forward temporal planner that does not use an explicit representation of time. In ATFP, duration of actions are temporarily ignored, and a causally valid order of beginnings and endings of actions is searched using classical forward heuristic...
Study ofthe NJL-Model Phase Diagram at Finite Temperature and Chemical Potential
,
M.Sc. Thesis
Sharif University of Technology
;
Rouhani, Shahin
(Supervisor)
;
Sadooghi, Neda
(Supervisor)
Abstract
We calculate NJL-Model free energy throughthe finite- temperature methods.Then according to the energy-gap equation, we determine symmetric and anti-symmetric phases under Chiral Transformation, in different regions of the phase diagram,with chemical potential() and temperature(T)as control parameter. We conclude with comparing the result of the finite temperature expansion to nonzero chemical potential to the result of,T=0 and finite ,andT=μregime.
How News Affect the Value of Bitcoin
, M.Sc. Thesis Sharif University of Technology ; Talebian, Masoud (Supervisor) ; Hajizadeh, Iman (Co-Supervisor)
Abstract
This research investigates the impact of Bitcoin and cryptocurrency news along with macroeconomic and financial indicators, on Bitcoin price fluctuations for two years (May 2016-2018). The reason for this examination is due to high variations of Bitcoin price in the late 2017 and beginning of 2018, while academic research focusing on Bitcoin price are mostly conducted before 2017. Findings show that the number of news with positive and negative contexts, and news related to cryptocurrency technology have a direct relationship with Bitcoin price change. The other result shows that among news concentrated on Bitcoin, the most effective is regarding adverse incidents, famous people concerns and...
Investigating the Effectiveness of Wells and Their Anti-Collision Analysis in a Percolation Reservoir Model
, M.Sc. Thesis Sharif University of Technology ; Masihi, Mohsen (Supervisor) ; Jamshidi, Saeed (Co-Supervisor)
Abstract
In drilling the percolation structure reservoirs (such as offshore Channelized reservoirs), one of the most important factors in the effectiveness of wells is drilling permeable areas (Channels), while Channel constraints make it possible for two wells to collide. On the other hand, if the desired reservoir is an offshore reservoir, these restrictions have been increased because usually several wells are drilled near together from one platform. Therefore, proper well collision analysis method is also important in these situations. In this project, anti-collision analysis is performed using the MWD device error model between two or more wells in a static reservoir model with channel...
Risk Assessment and Allocation of Public-Private Partnership in the Tehran Municipality
, M.Sc. Thesis Sharif University of Technology ; Sepehri, Mehran (Supervisor) ; Hajizadeh, Iman (Supervisor)
Abstract
Over the past two decades, in developed countries, public-private partnerships have been used as a mechanism to provide the required infrastructure by using private sector capacity. Risk management is the most critical factor in achieving optimal "value for money" in this type of project. In Iran, this is still far from its maturity and the growing trend of adopting this method and the vacuum of its academic literature in the country, necessitate such research. This study has been written to solve this problem due to the lack of risk management framework in the contracts of Tehran Municipality's Partnerships Organization. This dissertation covers three stages of risk management, which...
Aerodynamics Design of Aviation High-speed Radial Turbine with a Feasibility on Cooling
, M.Sc. Thesis Sharif University of Technology ; Ghorbanian, Kaveh (Supervisor)
Abstract
Radial turbines with small dimensions and in small power capacities are of great interest. In general, turbine performance improvement and higher output power may be achieved through increasing the inlet mass flow rates however at the expense of more weight and larger dimensions. On the other hand, increasing the inlet total temperature to the turbine will result in higher power potentials. Nevertheless, the turbine needs to be cooled in case that the intended inlet temperature goes beyond the turbine material limitation. In this thesis, radial turbine equations are reviewed and the logic of a 1D algorithm is developed where parameters like the total temperature, total pressure, and mass...
Experimental Study on Ship Added Resistance in Wave
, M.Sc. Thesis Sharif University of Technology ; Seif, Mohammad Saeed (Supervisor) ; Mehdigholi, Hamid (Supervisor)
Abstract
In the ship designing, it is preferable to access to a good performance in waves and low efficiency loss. Accordingly, modeling and estimation of added resistance would be an important issue. Added resistance in wave is an important part of ship's performance due to many technical and economic effects on the ship's performance. With understanding and awareness of the added resistance that comes from ship accident to the waves, we can reduce this parameter by changing in specifications and hull form of ships. Designers are also interested in optimizing the ship from this aspect. In previous works, added resistance in waves was obtained from experimental, numerical and analytical methods. In...
Experimental Study the Effect of Control Surface on High speed Vessels Maneuvering in Calm Water
, Ph.D. Dissertation Sharif University of Technology ; Seif, Mohammad Saeed (Supervisor) ; Mehdigholi, Hamid (Supervisor)
Abstract
Design optimization of ships by taking maneuverability in account has great influence on the performance of the vessels. Thus providing a method to predict the behavior of vessel in the design process is very important. Ship maneuverability is remarkable from different aspects of view. Especially in high speed vessels of various applications and missions’ good maneuverability would be a positive rating for it. For example, military vessels in specific situations need to change the speed and direction and this is a crucial capability of them. Also in accordance to the rules of IMO all of the vessels should perform maneuvering trials and fulfil the minimum requirements. Accordingly, this issue...