An Experimental Investigation of Unsteady Flow Over a Delta Wing in Supersonic Regime

, M.Sc. Thesis Sharif University of Technology Nazifi, Mohammad (Author) ; Soltani, Mohammad Reza (Supervisor)

Abstract

Focusing on unsteady flow field over delta wings due to vacuity of researches in this branch on one hand and requiring of modern aircrafts designers to this science on the other hand, expresses necessity of accomplishing present investigation. Scrutiny of pressure distribution of low aspect ratio wings in unsteady state and determination of aerodynamic characteristics of these wings in variant conditions, can be beneficial to plan aircrafts need to fly with high maneuverability in high speeds. This issue becomes important when in supersonic regime, with respect to emerged shock waves and vortices, develop complicated pressure distributions on the wing surface in unsteady state that affect...

The Effect of Interfaces on Heat Transport Mechanism of Y-Ba-Cu-O Thin Film Superconducting Bolometer

, Ph.D. Dissertation Sharif University of Technology Nazifi Takantapeh, Rana (Author) ; Vesaghi, Mohammad Ali (Supervisor) ; Fardmanesh, Mahdi (Supervisor)

Abstract

In this thesis, we are focusing on the heat transport mechanism in one of the most applicable kinds of superconducting detectors called, YBa2Cu3O7-x (YBCO) transition-edge bolometer. The Time Domain Thermoreflectance (TDTR) method is described as a tool for investigating the thermal boundary conductance and thermal conductivity of the materials, and the measured thermal conductivity of our YBCO films is reported here. Although some recent papers have shown a dependence of the thermal conductivity of the YBCO films to their thickness, our results on many samples with different substrates didn’t show the reported thickness dependency and we have obtained the thermal conductivity of the YBCO...

Critical Current Density Improvement in Type II Superconductors by Modifying the Type, Size and the Patterns of Pinning Centers

, M.Sc. Thesis Sharif University of Technology Nazifi Takantapeh, Rana (Author) ; Vesaghi, Mohammad Ali (Supervisor) ; Fardmanesh, Mehdi (Supervisor)

Abstract

Motion of magnetic flux, as a result of exerting electrical current, causes dissipation and voltage difference in the type II superconducting slab. So fixing these vortices by pinning centers will increase the critical current . Enhancing the critical current by different kinds of pinning centers is interesting for a lot of theoretical and experimental research groups. At first in this project dynamics of vortices in a triangular lattice is investigated by changing the pinning force. For the case of fp=2f0 we have seen two phase transition in velocity-force plot. And also a practical pinning array of parallel lines is presented. The effect of pinning force, pinning potential width and the...

Effect of low-level laser irradiation on the function of glycated catalase

, Article Journal of Lasers in Medical Sciences ; Volume 9, Issue 3 , 2018 , Pages 212-218 ; 20089783 (ISSN) Mirmiranpour, H ; Shams Nosrati, F ; Sobhani, O ; Nazifi Takantape, S ; Amjadi, A ; Sharif University of Technology

Laser Application in Medical Sciences Research Center 2018

Abstract

Introduction: The aim of this work is to evaluate the effect of low-level laser irradiation (LLLI), by lasers with different wavelengths, on glycated catalase enzyme in vitro experimentally. Methods: This is done by measuring the activity and structure properties of glycated catalase enzyme. The structure properties were evaluated with circular dichroism (CD) and fluoroscopy methods. Three continuous wave (CW) lasers in the visible spectrum (λ = 450, 530, 638 nm) and a 100-ns pulsed laser in the infrared spectrum (λ = 905 nm) were chosen for comparison. For the infrared laser, same effects have been investigated for different energy doses. The effect of photon energy (hλ) at different...

Wideband low-profile transmissive linear cross-polarizer for millimeter-wave applications

, Article Optics and Laser Technology ; Volume 163 , 2023 ; 00303992 (ISSN) Hajitabarmarznaki, S ; Ahmadi Boroujeni, M ; Shojaeian, S ; Nazifi, R ; Iman Mirzaei, S ; Fardmanesh, M ; Sharif University of Technology

Elsevier Ltd 2023

Abstract

In this article, we report on the design and fabrication of wideband high-efficiency linear cross-polarizers operating in transmission mode at millimeter waves. The proposed structures include a metasurface-based analyzer layer consisting of modified double asymmetric split-ring resonator elements. The proposed analyzer layer along with an optimized polarizer layer is integrated into an ultra-thin double-layer printed circuit board. A resonant cut-wire-based metasurface and a non-resonant wire-grid structure are designed as the polarizer layer. It is observed that the cross-polarized transmission coefficient and the polarization conversion ratio can noticeably be enhanced in the double-layer...

Millimeter-Wave response of all metal-organic deposited YBCO transition edge bolometer

, Article IEEE Transactions on Applied Superconductivity ; Volume 31, Issue 1 , 2021 ; 10518223 (ISSN) Nazifi, R ; Mohajeri, R ; Alipour, Z ; Mirzaei, S. I ; Ahmadi Boroujeni, M ; Vesaghi, M. A ; Grivel, J. C ; Fardmanesh, M ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2021

Abstract

We report on the response of a monolithic high Tc transition-edge bolometer to about 3 mmWave for the first time. The detector structure consisting of 400-nm YBa2Cu3O7-x(YBCO) film on buffered yttria stabilized zirconia substrate without any coupled antenna, shows bolometric type responsivity to the 3-mmWave radiation at its transition temperature. The YBCO thin film Ce0.9La0.1O2 buffer layer are both fabricated by the metal-organic deposition method. The meander line pattern of the bolometer is designed for obtaining maximum absorption and responsivity possible when the polarized radiation of the source is aligned with the pattern. Meander lines are 50 micrometers wide and 1.5-mm long. We...

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...

Iran’s Air Quality Modeling Using CMAQ-WRF Coupled Model

, M.Sc. Thesis Sharif University of Technology Mohegh, Mohammad Hassan (Author) ; Arhami, Mohammad (Supervisor)

Abstract

Industrialization has brought about air pollution which is one of the most important factors threatening human health. The most efficient method to improve air quality include preventing the emission of pollutants by making laws and regulations. In order to set appropriate regulations, there needs to be a correct understanding of the problem. The purpose of this research is to identify such factors and create a correct understnding of the problem in Iran by constructing a Model of Iranian air qulity. The model used in this research, CMAQ is one of the most comprehensive and state of the art models in transport of pollutnts and chemical reactions in the atmosphere. The inputs into CMAQ...

H.264 Decoder for Portable Application

, M.Sc. Thesis Sharif University of Technology Alizadeh, Mohammad Sadegh (Author) ; Sharifkhani, Mohammad (Supervisor)

Abstract

As mobile multimedia services become popular, it is expected that mobile devices provide more multimedia functions such as real-time video playback, TV watching, and video games. However, real-time video applications running on mobile devices are heavily constrained by their limited computing power, compared to high-end consumer devices. In order to playback a high resolution video on mobile devices, a typical approach would be to fully decode video bitstream into the pixel-domain, and then spatially downscale the decoded frames at a desired resolution. However, due to large computation and memory required for decoding followed by downscaling, this approach is unsuitable for real-time video...