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    Study on Biodiesel Production Using Engineered Lipases

    , M.Sc. Thesis Sharif University of Technology Char Roostaei, Hamzeh (Author) ; Kazemeini, Mohammad (Supervisor)
    Abstract
    Biodiesel has drawn the attention of many researches to itself as a replacing source for crude oil, recently. Transesterification is one of the most popular methods used for biodiesel production. Enzyme transesterification is a more simple method in comparison with acidic or basic transesterification. However, the high price and low yield of enzyme transesterification has caused many obstacles in its application. Enzyme engineering has gained much attention as a way to improve enzyme performance. In this thesis, biodiesel production by a native enzyme named Bacillus thermocatenulatus, and two engineered-enzymes is studied. First, effective parameters and variables in biodiesel production by... 

    Numerical Modeling and Experimental Investigation of the Efficiency of the Laser-assisted Machining for Ceramics

    , Ph.D. Dissertation Sharif University of Technology Roostaei, Hossein (Author) ; Movahhedy, Mohammad Reza (Supervisor) ; Shoja Razavi, Reza (Co-Supervisor)
    Abstract
    Laser-assisted machining is nowadays considered as an alternative to conventional machining processes including ceramics grinding, which has provided the basis for extensive experimental and numerical studies in this field. Since the main difference between laser-assisted machining and conventional machining is in the presence of lasers, the main purpose of this study was to investigate the effects of laser on the laser assisted machining process. In this regard, in the first step the process of laser heating to the ceramic workpiece has been studied experimentally and numerically by finite element method. The material used in this research is a slip cast fused silica ceramic. The... 

    Emergency Medical Service Centers Location

    , M.Sc. Thesis Sharif University of Technology Roostaei, Ali (Author) ; Eshghi, Kourosh (Supervisor)
    Abstract
    The Emergency Medical Services (EMS) have a major role in decreasing the mortality rate and reducing the non-reversible effects of injuries by on time care to patients and transporting them to hospitals if it is needed. Since there is an important goal directly related to the human life, any research or study to improve the performance of EMS is highly recommended. One of the most important parameters in evaluation of EMS is to measure the coverage time of a demand. The locations of EMS play substantial role to decrease the response time. So the locations of EMS stations are very important especially in large and populated cities. Mainly, there are three problems that EMS managers should... 

    Emergence of Hopf bifurcation in an extended SIR dynamic

    , Article PLoS ONE ; Volume 17, Issue 10 October , 2022 ; 19326203 (ISSN) Roostaei, A ; Barzegar, H ; Ghanbarnejad, F ; Sharif University of Technology
    Public Library of Science  2022
    Abstract
    In this paper, the original SIR model is improved by considering a new compartment, representing the hospitalization of critical cases. A system of differential equations with four blocks is developed to analyze the treatment of severe cases in an Intensive Care Unit (ICU). The outgoing rate of the infected individuals who survive is divided into nI and bI/1+b where the second term represents the transition rate of critical cases that are hospitalized in ICU. The findings demonstrate the existence of forward, backward and Hopf bifurcations in various ranges of parameters. © 2022 Roostaei et al. This is an open access article distributed under the terms of the Creative Commons Attribution... 

    Investigation of the Effect of Slip Length on the Electrokinetic Behavior of Conical-Shaped Nanochannels

    , M.Sc. Thesis Sharif University of Technology Roostaei, Mahmoud (Author) ; Mohammadi, Ali Asghar (Supervisor)
    Abstract
    Conical nanochannels have desirable electrokinetic properties due to asymmetry,including ionic current rectification and ion selectivity. The present study numerically addressed the effect of slip length on the ionic current rectification and ion selectivity in conical-shaped electrolyte-loaded nanochannels with and without a coated polyelectrolyte layer. The electrolyte was considered a salted incompressible Newtonian fluid. The polyelectrolyte layer was also modeled as a rigid and charged porous solid saturated with a salted Newtonian fluid. The electrolyte-polyelectrolyte layer interface was modeled as a surface, considering ion partitioning with distinct physical properties across the... 

    Effects of a multi-component virtual reality program on motor skills and functional postural control in children with hemiplegic cerebral palsy

    , Article Heliyon ; Volume 9, Issue 9 , 2023 ; 24058440 (ISSN) Roostaei, M ; Babaee, M ; Alavian, S ; Jafari, N ; Rayegani, M ; Behzadipour, S ; Sharif University of Technology
    Elsevier Ltd  2023
    Abstract
    Background: Pediatric neurorehabilitation has recently employed virtual reality (VR) technologies as a platform to design and implement novel modalities. Aims: To evaluate the feasibility of a multi-component VR-based program on motor skills and functional postural control for children with hemiplegic cerebral palsy (HCP). Methods: A single-case-experimental design was conducted on eight children with HCP (12.33 ± 4.71 years and GMFCS= II, I). The VR-based program consisted of 3 sessions per week for four weeks. Timed Up and Go (TUG) test, Functional Reach Test (FRT), Pediatric Balance Scale (PBS), Activities Scale for Kids (ASK), ABILHAND-Kids, and Box and Block Test (BBT) were used to... 

    Forecasting Electricity Consumption in a Metropolis Using Machine Learning Algorithms

    , M.Sc. Thesis Sharif University of Technology Roostaei, Mohammad (Author) ; Taghizadeh Manzari, Mehrdad (Supervisor) ; Aryanpour, Masoud (Supervisor)
    Abstract
    In smart grids, energy data such as electricity and gas consumption are recorded via smart sensors installed in buildings. Analyzing energy consumption patterns and classifying users based on their consumption behavior can assist policymakers in supply management and urban-scale energy control. This study proposes an unsupervised approach to classify energy consumers according to their monthly consumption patterns. The primary objective of the clustering is to group households with similar usage behaviors, facilitating a more effective analysis of electricity consumption at an urban scale. The K-means clustering algorithm is employed to classify households into K clusters based on their... 

    Analysis of Heat Transfer in Laser Assisted Machining of Slip Cast Fused Silica Ceramics

    , Article 7th CIRP Conference on High Performance Cutting, HPC 2016, 31 May 2016 through 2 June 2016 ; Volume 46 , 2016 , Pages 571-574 ; 22128271 (ISSN) Roostaei, H ; Movahhedy, M. R ; Ihlefeldt S ; Wertheim R ; Hochmuth C ; Putz M ; Sharif University of Technology
    Elsevier  2016
    Abstract
    Machining of ceramics often involves many challenges due to their high hardness, brittleness, and low thermal properties. Laser assisted machining (LAM) is a promising technology for improving the machinability of hard-to-cut materials. In this work, laser assisted machining of slip cast fused silica (SCFS) ceramics is investigated by presenting a numerical thermal analysis of laser effects on material behaviour. A transient three-dimensional heat transfer analysis for laser assisted turning of SCFS is performed using finite element method. Temperature distributions in SCFS cylindrical specimens are obtained. Experimental results are provided to validate the numerical results  

    Construction of an Experimental Device for Foaming Agent and an Experimental Study of the Properties of Foaming Agent

    , M.Sc. Thesis Sharif University of Technology Mohammad Karami (Author) ; Bazargan, Mohammad (Supervisor)
    Abstract
    The primary purpose of acidizing operations in the oil and gas industry is to enhance hydrocarbon production. Acidizing has been a common and conventional method for years, especially when production engineers face issues like declining reservoir pressure leading to reduced production rates. Initially, the treatment solution is referred to as matrix acidizing. In acidizing operations, different additives are combined with the acid to control its behavior in the reservoir. These additives may include iron control agents, corrosion inhibitors, friction reducers, and more. Incompatibility among these additives, the acid, and reservoir fluids can lead to severe damage to the reservoir.... 

    Numerical Analysis of An Annular Gas Turbine Combustor

    , M.Sc. Thesis Sharif University of Technology Gandomi, Mohammad Hossein (Author) ; Farshchi, Mohammad (Supervisor)
    Abstract
    The goal of this research is the simulation of the annular combustion chamber of the turbine engine utilized by liquid fuel. The achievement to this goal will lead to create numerical tools for parametric study, analysis and combustion chamber designing.For this reason simple geometry has been considered. This simplicity of geometry causes to facilitate in parametric study and decrease in saving time for modeling and meshing. This combustion chamber is a simplified model of engine CF6. In recent study, the k – ε realizable model has been used for turbulence modeling. For non-adiabatic condition, chemical reaction is dissolved by utilizing probability density function along with laminar... 

    A misbehavior‐tolerant multipath routing protocol for wireless Ad hoc networks [electronic resource]

    , Article International Journal of Research in Wireless Systems (IJRWS) ; Vol. 2, Issue 9, pp. , Sep. 2013 Sedghi, H. (Haniyeh) ; Pakravan, Mohammad Reza ; Aref, Mohammad Reza ; Sharif University of Technology
    Abstract
    Secure routing is a major key to service maintenance in ad hoc networks. Ad hoc nature exposes the network to several types of node misbehavior or attacks. As a result of the resource limitations in such networks nodes may have a tendency to behave selfishly. Selfish behavior can have drastic impacts on network performance. We have proposed a Misbehavior-Tolerant Multipath Routing protocol (MTMR) which detects and punishes all types of misbehavior such as selfish behavior, wormhole, sinkhole and grey-hole attacks. The protocol utilizes a proactive approach to enforce cooperation. In addition, it uses a novel data redirection method to mitigate the impact of node misbehavior on network... 

    Theoretical and Experimental Study to Conversion of AUC to UO2 by Microwave Heating

    , Ph.D. Dissertation Sharif University of Technology Labbaf, Mohammad Hossein (Author) ; Otukesh, Mohammad (Supervisor) ; Ghannadi Maragheh, Mohammad (Co-Advisor) ; Ghasemi, Mohammad Reza (Co-Advisor)

    SAR Imaging Using the TomoSAR Technique to Resolve Multiple Scatterers

    , M.Sc. Thesis Sharif University of Technology Omati, Mohammad Mahdi (Author) ; Bastani, Mohammad Hassan (Supervisor) ; Karbasi, Mohammad (Co-Supervisor)
    Abstract
    During the last few years, the study of urban environment structures is considered as a research field of interest in remote sensing. In satellite observations of the earth's surface, continuous imaging in terms of time and space has caused the remote sensing technique to be proposed as a useful and efficient tool for the analysis of urban areas. Obtaining quantitative spatial information from the urban environment in fields such as determining the height of buildings plays an essential role in urban planning, monitoring damage to buildings, establishing communication bases and digital cities. During the last two decades, the use of Tomosar approach in order to reconstruct the structures of... 

    Estimating Possible Effects of Subsidies in Competition and Development of Fixed Broadband Internet

    , M.Sc. Thesis Sharif University of Technology Mohammadi, Mohammad Ali (Author) ; Vesal, Mohammad (Supervisor) ; Rahmati, Mohammad Hossein (Supervisor)
    Abstract
    In this work, the dynamic competition between firms providing internet services is studied. The framework is Markov equilibrium whereby structural parameters are obtained using two-step estimations, allowing for analyzing the situation in case of subsidies for service upgrade. The results show that such subsidy has little effect on the number of firms while increasing the number of fast firms  

    Estimating Price Elasticity of Natural Gas Demand in Iran's Residential Sector: A Regression Discontinuity Approach

    , M.Sc. Thesis Sharif University of Technology Makhsousi, Mohammad Hossein (Author) ; Rahmati, Mohammad Hossein (Supervisor) ; Vesal, Mohammad (Supervisor)
    Abstract
    Estimating the price elasticity of gas demand involves complexities depending on the gas market structure and pricing mechanisms in different countries. Distinguishing between supply and demand shocks and block pricing are among the main challenges that can cause endogeneity in elasticity estimates. Iran's domestic gas network, one of the largest and most extensive household gas markets, is divided into five climatic zones based on weather conditions. The pricing steps for these five climates during the five cold months are such that a customer in a warmer climate pays higher prices. Conversely, the pricing steps for the seven warm months are the same for all climates. This policy creates a... 

    Estimate the Effect of Religiosity on Voter Turnout

    , M.Sc. Thesis Sharif University of Technology Jarrahi, Mohammad Mahdi (Author) ; Rahmati, Mohammad Hossein (Supervisor) ; Vesal, Mohammad (Supervisor)
    Abstract
    The correlation between religious adherence and voter turnout is widely studied. However, whether the relation is causal is an open question. We use Household Expenditures and Income Survey (HEIS) data in Iran, which encompasses nine distinct religious expenditures. These expenditures have low correlation with each other and represent different aspects of religious adherence. We use Imamzadeh (some historical holy shrines) as Instruments to estimate the causal effect of religious expenditures on voter turnout. The results reveal that religious expenditures influence both presidential and parliamentary voter turnout, with a notably stronger impact on presidential elections  

    Joint Optimization of Computation Offloading and Resource Allocation in Mobile Edge Computing Networks

    , M.Sc. Thesis Sharif University of Technology Shokouhi, Mohammad Hossein (Author) ; Pakravan, Mohammad Reza (Supervisor) ; Hadi, Mohammad (Co-Supervisor)
    Abstract
    Mobile edge computing (MEC) is a promising technology that aims to resolve cloud computing’s issues by deploying computation resources at the edge of mobile network and in the proximity of users. The advantages of MEC include reduced latency, energy consumption, and load on access and mobile core networks, to name but a few. Despite all the aforementioned advantages, the mobility of mobile network users causes the traditional MEC architecture to suffer from several issues, such as decreased efficiency and frequent service interruption. One of the methods to manage users’ mobility is virtual machine (VM) migration, where the VM containing the user’s task is migrated to somewhere closer to... 

    Non-Scratch, Antibacterial And Self-cleaning SiO2/TiO2 Nano Composite Coating on Surgical Tools By Sol-Gel

    , M.Sc. Thesis Sharif University of Technology Ahmadi, Mohammad Hossein (Author) ; Ghorbani, Mohammad (Supervisor)
    Abstract
    In this study TiO2/SiO2 thin films were prepared by sol-gel method from Tetra isopropylortho Titanate(TIPT) as the principle of TiO2 material with Tera ethoxysilane(TEOS) as the principle of SiO2 material to achieve high scratch-resistant , antibacterial and self-cleaning surface area under the effect of various percentage of SiO2 . Film deposition was carried out using a dip-coating technique and heat-treatment was used at 700ºC to achieve crystalline of films with excellent adherence the of substrate.
    The surface morphology of the films has been observed by Scanning Electron Microscope (SEM) and the tribological properties of the surface were investigated by Atomic Force Microscope... 

    Simulation and Control of an Aromatic Extractive Distillation Column

    , M.Sc. Thesis Sharif University of Technology Karima, Mohammad Mahdi (Author) ; Shahrokhi, Mohammad (Supervisor)
    Abstract
    In this study steady state and dynamic simulation of an NFM extractive distillation unit for seperation of aromatics and non-aromatic components has been carried out. Column output composition obtained with experimental binary coefficients is compared with those obtainded by UNIFAC equation. The results indicate that using UNIFAC for all binrary coefficients results in an unacceptable error in concentration of benzene. If the experimental binary coefficents of benzene with NFM are used and the rest are calculated by UNIFAC equation, the simulation results will be very close to those obtained via experimental binary coefficients. Also it is shown that considering a constant efficiency for all... 

    Investigation the Effects of Parking Pricing and Improving Public Transportation Policies on Private Car Use Reduction in Central Business District

    , M.Sc. Thesis Sharif University of Technology Salavati, Mohammad Ali (Author) ; Kermanshah, Mohammad (Supervisor)
    Abstract
    Nowadays, with population growth and vehicle traffic increase, only providing transportation supply couldn’t answer the transportation demand. One of the most important solutions to reduce traffic is transportation demand management (TDM). In this research, the effects of parking pricing and improving public transportation services on private car demand reduction in city center are examined. The data are collected from private cars users in the city center of Isfahan through interviews. By stated preference method, the impacts of parking price and public transit travel time and other related factors were investigated. For this purpose, binary logit, multinomial logit and nested logit models...