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    Numerical Solution of Stochastic Differential Equations with Different Methods

    , M.Sc. Thesis Sharif University of Technology Qeysari, Mahmood (Author) ; Zohuri Zangeneh, Bijan (Supervisor) ; Razvan, Mohammad Reza (Supervisor)

    Numerical Simulation of Cavitation in Rigid Body Motion in Unsteady State

    , M.Sc. Thesis Sharif University of Technology Asnaghi, Abolfazl (Author) ; Seif, Mohammad Saeed (Supervisor)
    Abstract
    In this thesis, cavitating flow over 2D/3D geometries of cavitators and projectile bodies in stationary and moving conditions are simulated using the "Volume of Fluid" (VOF) technique. The main application of VOF model is for simulating free surface flows. In this work, another capability is added to the VOF algorithm to solve for gas phase and by applying analytical-numerical mass transfer models, cavitation phenomenon is simulated. The developed algorithm precisely simulates the geometrical parameters of supercavities such as dimension and shape in a wide range of cavitation numbers. In addition, the flow parameters of supercavity such as drag coefficient, pressure coefficient inside the... 

    A Mathematical Model to Prediction of the Formation of Microporsities in Aluminium Alloy Cast Parts

    , M.Sc. Thesis Sharif University of Technology Bahmani, Ahmad (Author) ; Varahram, Naser (Supervisor) ; Davami, Parviz (Supervisor)
    Abstract
    Today, application of aluminium alloys in industries is developing. And this is because of some specification of these alloys like high proportion of the Strength per weight. One of the most useful alloys of this alloy group is A356 alloy that contain 7 % Silicon and 0.4 Percent of magnesium, this alloy because of cast ability, heat treat ability specification is use developing in air and automotive industries. But usage of this alloys combined with some difficulties like low fluidity and formation of shrinkage and gas porosities in this alloys. In present work with programmer software Visual Fortran, based on Finite difference method, a simulation model has been developed, can solve heat... 

    Investigation of Fouling In Clarification of Non-Alcoholic Beer with Crossflow Microfiltration Membranes

    , M.Sc. Thesis Sharif University of Technology Hajipour Shirazifard, Mastaneh (Author) ; Soltanieh, Mohammad (Supervisor)
    Abstract
    In the present work, numerical simulation of cross-flow microfiltration of non-alcoholic beer in a tubular membrane has been studied. Finite element analysis was used as a powerful tool for simulation. The feed stream, which flows mainly tangentially to the porous membrane surface, is modeled by the Navier-Stokes equations. Porous wall conditions are described by the Darcy equation that relates the pressure gradient within a flow stream to the flow rate through the permeable wall. A pilot-scale cross-flow membrane filter was developed to verify the model results. Ceramic tubular membranes were used in this study. The cross-flow velocity of the feed solution was controlled at the laminar... 

    Evaluating the Effects of Operating Conditions on Particle Size and Molecular Weight Distributions in Emulsion Polymerization of Styrene

    , M.Sc. Thesis Sharif University of Technology Vafa, Ehsan (Author) ; Shahrokhi, Mohammad (Supervisor)
    Abstract
    In this work, a comprehensive dynamic model has been used for styrene emulsion polymerization in a semi-batch reactor to predict the evolution of product particle size and molecular weight distributions under non-isothermal condition. Method of moments has been applied for solving the population balance equations and the results are compared with the results obtained from finite-volume method as a precise technique. A sensitivity analysis respect to perturbation in initial values of various reagents, species and the reactor temperature has been performed to identify suitable manipulated variables for closed-loop control of the reactor. The detailed model is used to generate optimal feed... 

    Investigation of Nucleation and Growth of Metallic Nanoparticlaes from the Gas Phase by Molecular Dynamic Simulation

    , M.Sc. Thesis Sharif University of Technology Naghibi Nezhad, Mohsen (Author) ; Askari, Masoud (Supervisor) ; Simchi, Abdolreza (Supervisor)
    Abstract
    Formation of nanoparticles by the gas phase condensation process is one of the most promising methods for the nanoparticles synthesis. Finding the correlations between adjustable parameters of the process and nanoparticles properties depends on how parameters affect the mechanism of nucleation and growth. The use of classical nucleation theory at nanoscale leads to unacceptable results; hence, approaches such as molecular dynamic simulation (MD) have been proposed to investigate the mechanism of nucleation and growth at atomic scale. In the present work, the formation of iron clusters from a supersaturated gas phase was investigated via molecular dynamics simulation. For thermalization of... 

    Modeling of Walking in a Gait Trainer, to Modify and Optimize Its Mechanism

    , M.Sc. Thesis Sharif University of Technology Salehy Aminy, Mohammad (Author) ; Farahmand, Farzam (Supervisor) ; Narimani, Roya (Supervisor)
    Abstract
    Several diseases and injuries may cause disability in locomotion (especially walking). Spinal cord injuries, brain stroke and disease like Parkinson are the most major causes. In the past, some efforts has been made to reduce the effect of organ’s disabilities, but today, there is the chance of healing the spinal cord injury By using new (Schwann Cell) method. Due to long time stillness and severe muscles weakness; condensed physiotherapy exercise is essential to recover locomotion abilities, particularly in walking. In this way, if the practices matches with the normal walking (especially weight bearing); it has more physiological and psychological effect. In order to achieve this goal, a... 

    Simulation of Hydrodesulfurization Plant

    , M.Sc. Thesis Sharif University of Technology Sadat Feizabadi Sani, Mansooreh (Author) ; Fahadi, Fathollah (Supervisor)
    Abstract
    Sulfur components are one of the most important impurities in various petroleum fractions that cause many problems in refining and consumption. In this thesis, hydrodesulfurization process, which has an economical and environmental especial position in petroleum and other related industries, has been discussed. In hydrodesulfurization process, under specific operation condition, sulfur components are converted catalytically to the H2S in a fixed bed reactor. In this study dibenzothiophene, which is one of the most strength and complex sulfur components, is considered as the base component. A Langmuir-Hinshelwood kinetic equation is used to describe the reaction by using the commercial... 

    History Matching using Streamline Simulation

    , M.Sc. Thesis Sharif University of Technology Shojaei, Hasan (Author) ; Pishvaie, Mahmoud Reza (Supervisor) ; Badakhshan, Amir (Supervisor) ; Kamali, Mohammad Reza (Supervisor)
    Abstract
    Management decisions, Enhanced Oil Recovery, and reservoir development plans in petroleum industries are based on predictions by reservoir simulation. Due to uncertainties in model parameters or engineering assumptions, the simulation results are not accurate, while they are correct. One remedy is to match simulation results with engineering measurements, typically pressure and flow rate, by adjusting model parameters. In Reservoir Engineering literature, this is called History Matching and is an optimization problem. Common methods of history matching are based on finite difference simulation, and therefore have a very low speed. In addition, these methods usually ignore Geostatistical... 

    Semi-Analytical Modeling And Simulation Of Heavy Oil Recovery Through VAPEX Process

    , M.Sc. Thesis Sharif University of Technology Rasti, Fariba (Author) ; Masihi, Mohsen (Supervisor) ; Kharrat, Riyaz (Supervisor)
    Abstract
    VAPEX is a relatively new EOR process for the recovery of heavy oil. In this process solvent is used to form a vapor chamber within a reservoir. Vapor dissolves in the oil and diluted oil drains by gravity to a horizontal production well. The essential features of this recovery mechanism have been discussed in this study. Furthermore, a semi-analytical and a simulation study of VAPEX process have been performed on a specified Iranian heavy oil reservoir (such as Kuh-e-Mond). The aim of this study is to investigate an exponential functionality (correlation) witch incorporates all physical parameters that affect the production rate of VAPEX process in dimensionless form. The adjustable... 

    Modifications in Commercial Diesel Engines to Perform Under Difficult Respiration Conditions

    , M.Sc. Thesis Sharif University of Technology Moussavi Torshizi, Abolfazl (Author) ; Durali, Mohammad (Supervisor)
    Abstract
    In this project we are about to adopt a method for implementing commercial diesel engines (truck and bus engines) in applications with difficult respiration condition like what happens in a submarine. To this end, working conditions of such engines are introduced and standard constraints are explained. Then the structure of already manufactured submarine engines is presented. At this point an engine from known manufacturers was selected for calculations to be performed on it. Since test and measurement equipments were not yet ready, simulation using computer software (GT-POWER v6.1) was selected as the solving method. First, the engine was modeled in its nominal working conditions. After... 

    Auto thermal reforming of natural gas
    Surveying Feed Specification on the Effluent Quality as the Feedstock of a Methanol Unit and its Optimization

    , M.Sc. Thesis Sharif University of Technology abtahi, mohammad hossein (Author) ; farhadi, Fatollah (Supervisor)
    Abstract
    Synthesis gas is a gaseous mixture which mainly consists of carbon monoxide and hydrogen. Different methods are used to produce synthesis gas but the most important method is auto thermal reforming. This method is based upon catalytic reactions. Steam, oxygen and natural gas are the influents to the reactor and synthesis gas will be the effluent. Ni catalysts on alpha-alumina as the support media are usually used in this process. These catalysts are highly heat resistant and insure great qualifications for reactions. This thesis tries to find best solutions of synthesis gas production suitable for feeding to a methanol production unit. There are four main reactions. Three of which are highly... 

    Fractional Brownian Motion and Stochastic Differential Equations Driven by Fractional Noise

    , Ph.D. Dissertation Sharif University of Technology Naghshineh Arjmand, Omid (Author) ; Zohori Zangeneh, Bijan (Supervisor)
    Abstract
    This thesis has been prepared in six chapters. In the first chapter, the necessary analytical preliminaries are revised. The second chapter is specified on the introducing of the fractional Brownian motion and the description of some of its properties. The subject of the third chapter is simulation. The practical utilization of stochastic models usually needs simulation; therefore the fractional Brownian motion and the processes derived from it are not exempted either. The fifth chapter is consisted of two major parts; the first part is the simulation of fractional Brownian motion, in which no new work has been done, and only one of the available methods has been explained. The second part... 

    The Simulation and Active Control of a Centrifugal Compressor to Improve Compressor Performance & Reduce Energy Consumption

    , M.Sc. Thesis Sharif University of Technology Jokar, Ali (Author) ; Ghofrani, Mohammad Bagher (Supervisor) ; Zomordian, Rozbeh (Supervisor)
    Abstract
    In this thesis, we consider the simulation and active control of a centrifugal compressor in during surge occurrence. Surge, as an aerodynamic instability in compressors, causes to severe decrease of efficiency and loss of energy and with stabilizing the compressor in this condition, efficiency and system reliability increase. Nowadays, anti surge systems are used for surge avoidance in different industrials. They recycle the compressed gas from compressor down-stream to up-stream in instability condition and cause to exit the operation point from unstable zone. In this thesis, at first compression system is modeled based on Greitzer model and governing equation of compressor shaft in surge... 

    Simultaneous Fires Simulation in Two or Three Adjacent Tanks Using Computational Fluid Dynamic (CFD) Technique

    , M.Sc. Thesis Sharif University of Technology Bab, Vahid (Author) ; Rashtchian, Davood (Supervisor)
    Abstract
    In this thesis, behavior of multiple pool fires was investigated in the numerical method. Fire modeling is a complex process. The complexity intensify when simultaneous fires occurred, pool fire is the most likely among all kind of fires in city and industrial units. FDS software, a common CFD model for fire simulation, was used to simulate multiple pool fires. Using of CFD models is one of the most advanced techniques to fire simulation and FDS software have been used by engineers and researchers due to using of this technique. In the beginning, review of the existing investigations which FDS performance was examined of fire simulation is presented. Besides of the data gathering, in this... 

    Feasibility and Performance Analysis of a Thermoacoustic Heat Pump

    , M.Sc. Thesis Sharif University of Technology Askari, Rasoul (Author) ; Ghorbanian, Kaveh (Supervisor)
    Abstract
    Thermoacoustics deals with the conversion of heat energy into sound energy and vice versa. This new and emerging technology has a strong potential towards the development of sustainable and renewable energy systems by utilizing waste heat or solar energy. Although thermoacoustic devices are simple to fabricate; however, the design process is very challenging. The thermoacoustic phenomenon is discovered over a century ago; nevertheless, the rapid advancement in this field occurred during the past three decades when the theoretical understanding of the phenomenon is developed along with the prototype devices. There are several advantages of heat engines and refrigerators based on... 

    Experimental and Simulation Study of Asphaltene Deposition in Porous Media

    , M.Sc. Thesis Sharif University of Technology Khalili, Mohammad (Author) ; Ghotbi, sirous (Supervisor) ; Kharrat, Reyaz (Supervisor)
    Abstract
    Asphaltene deposition on reservoir rocks occurs during natural depletion as well as miscible injection processes. It causes reduction of effective pore space and consequent impairment of the ability of oil to flow through reservoir. Therefore, deposition of asphaltene causes significant formation damage and wellbore plugging, requiring expensive and difficult cleanup procedures. Thus it is necessary to be able to consider the onset, amount of deposition and also consequent damage of permeability and porosity reduction due to various factors. The objective of current work is to conduct experimental and simulation study of asphaltene deposition dynamics in one of the Iranian reservoirs. In... 

    Performance Evaluation of Recovery Based Routing Algorithms in Irregular Mesh NoCs

    , M.Sc. Thesis Sharif University of Technology Hosseingholi, Mahdieh (Author) ; Sarbazi Azad, Hamid (Supervisor)
    Abstract
    Heterogeneity is one of the challenges in the current NoC (Network-on-Chip) domain which oblige designers to consider less regular topologies to provide the best cost-performance trade-off while minimizing resource and power consumption and providing the maximum flexibility. Irregular mesh is a topology which combines the benefits of regularity and advantage of irregularity. Another important issue in any NoC is the selection of routing algorithm which provides the best performance. Routing algorithms especially those coupled with wormhole switching should deal with deadlock occurrences. Deadlock detection and recovery-based routing schemes for this type of switching gained attraction since... 

    Design and Simulation (& Manufacturing) of A Micro-Gyroscope

    , M.Sc. Thesis Sharif University of Technology Soltani, Arman (Author) ; Akbari, Javad (Supervisor)
    Abstract
    Nowadays, microgyroscopes are among the most important products of MEMS. The production of small, precise and inexpensive gyroscopes has become possible as the result of recent developments in fabrication technology. In this thesis it is intended to introduce a new method for manufacturing more precise microgyroscopes regarding manufacture facilities. Using this new method, sensitivity and resistance of microgyroscopes are increased against noises which are primarily caused by vibration and rotation about undesirable axes. The rotational movement imposed on the gyro is detected through fluid flow within its torus channel. This transformation facilitates the measurement of the initial motion.... 

    Performance Evaluation of Deadlock Avoidance Based Routing Algorithms in Irregular Mesh NoCs

    , M.Sc. Thesis Sharif University of Technology Mahdavinia, Parisa (Author) ; Sarbazi Azad, Hamid (Supervisor)
    Abstract
    It is now possible to integrate hundreds of modules (e.g. processors, memories) in a single silicon die. Handling the communication requirements between such modules by interconnecting them using shared buses is not possible from the performance point of view. One of the solutions is to use a network-on-chip (NoC) based communication infrastructure. NoCs were shown to be effective for solving the global interconnection problem among modules. These architectures emphasize the separation between computing and communication, and guarantee a good degree of design reuse and scalability. Mesh topology is favored by many researchers as the topology of NoCs because of its layout efficiency....