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Micromechanic Failure Analysis of Carbon/Phenolic Composite Conic Structures under Thermal Loading
, M.Sc. Thesis Sharif University of Technology ; Hosseini Kordkheili, Ali (Supervisor)
Abstract
In this study, through explaining a micromechanical model of progressive damage, failure in a composite conical structure under mechanical and thermal loads with 36 layers of carbon/phenolic material have been studied. To this end, first, mechanical behaviors of composite layers in micro and macro scale and their properties via fiber and matrix characterizations are discussed. In the following, selection of a proper RVE along with different types of boundary conditions on RVE are discussed. Then stress reinforcement coefficients in order to convert the mechanical and thermal stresses from macro to micro scale for carbon / phenolic material are extracted through defining appropriate RVE for...
Banks Money Creation and the Transmission Mechanism of Shocks
, M.Sc. Thesis Sharif University of Technology ; Madanizadeh, Ali (Supervisor) ; Mahmoodzadeh, Amineh (Supervisor)
Abstract
Banks are not only money brokers but also money creators. The ability of a bank to create money is due to its unique feature in issuing debts (deposits) that are accepted as a medium of exchange by economic agents. Although this bank function has been discussed under the "liquidity transformation" heading under the micro-banking literature, it has been less discussed in macro literature. In this study, we want to examine the consequences of the bank's liquidity transformation function by developing a New-Keynesian model in which banks can finance the economy by voluntarily expanding their balance sheet. To identify the mechanisms that the money creator bank creates in the model, we have...
Effect of Oleuropein as Green Inhibitor on Corrosion Protection of Painted Steel
, M.Sc. Thesis Sharif University of Technology ; Ghorbani, Mohammad (Supervisor)
Abstract
The corrosion rate of steel (EN 10130 DC-04) in the presence of oleuropein in aqueous corrosive solutions (of different concentrations in 1M and 0.5M hydrochloric acid and also 3.5% sodium chloride) evaluated and results was shown that oleuropein can protect steel surfaces and it acts as good inhibitor. This means that the observations of linear polarization and weight loss experiments showed inhibitor efficiency more than 97% in acidic corrosive medium and above 74% for aqueous solution of 3.5% sodium chloride. Adding oleuropein at different concentrations (i.e. 300 ppm, 700 ppm, and 1000 ppm) to three different types of polymeric paint structures (nitrocellulose alkyd base, acrylic base,...
Hydroxyapaptite Coating on Zirconia Toughened Alumina Nanocomposite by Biomimetic Method
, M.Sc. Thesis Sharif University of Technology ; Nemati, Ali (Supervisor) ; Salahi, Esmaeil (Co-Advisor)
Abstract
Zirconia toughened alumina (ZTA) Nanocomposites were prepared using nano sized Zirconia (ZrO2) powders doped with 3% mol of yttria (Y2O3) nanopowders and the sintering behavior at different temperature (1450 °C, 1550 °C and 1650 °C) were studied. The ZTA composite with different amount of partially stabilized Zirconia (PSZ)(5, 10, 15 and 20% mol) were prepared via axial pressing and then sintered to achieve maximum densification. After that phase changes of the samples were monitored. SEM was used for microstructural study and hardness and fracture toughness were determined by means of Vickers indentation. X-ray diffraction pattern showed that at constant composition, tetragonal zirconia...
Microwave Inspired Easy-to-Design Nano-Couplers for Hybrid Photonic-Plasmonic Waveguide Structures
, M.Sc. Thesis Sharif University of Technology ; Mehrany, Khashayar (Supervisor)
Abstract
Potential of plasmonic waveguide structures to confine light in sub-wavelength scales attracted many attentions in recent years. Among these structures planar metal-insulator-metal waveguide and plasmonic slot waveguide are more promising. That is because of their easy fabrication process along with their various reported applications. However, there are some obstacles in the path of developing plasmonic integrated circuits, among whichhigh propagation loss can be named as the most important. To solve this issue, photonic waveguides can be used as the lossless interconnections between small footprint plasmonic components on optical chips. Therefore, application of plasmonic slot waveguide...
Formal Analysis of Ad Hoc Network Protocols Using Process Algebra
, Ph.D. Dissertation Sharif University of Technology ; Movaghar Rahimabadi, Ali (Supervisor)
Abstract
Wireless Ad hoc Networks (MANET) are decentrilized networks, without any static infrastructure.In these networks, nodes communicate directly or indirectly via other nodes. They could move arbitrary, which makes the underlying topology dynamic. Therefore, MANET protocols not only should operate correctly, but they should be able to tolerate faults that
may arise due to unreliable wireless communication and unexpected changes in the underlying topology, while the quality of service metrics in benchmarks are satisfied. Therefore a unified framework for verification and evaluation of MANET protocols would alleviate the design process of such protocols.In this thesis, we provide a formal...
may arise due to unreliable wireless communication and unexpected changes in the underlying topology, while the quality of service metrics in benchmarks are satisfied. Therefore a unified framework for verification and evaluation of MANET protocols would alleviate the design process of such protocols.In this thesis, we provide a formal...
To Investigate Existence of Equity Premium Puzzel in Tehran Stock Exchange By Stochastic Dominance Method
, M.Sc. Thesis Sharif University of Technology ; Keshavarz Haddad, Gholamreza (Supervisor)
Abstract
In the last 4 years, while the annual investment return on 5 years bank deposits was 25 percent; the total index of Tehran Stock Exchange on average grew by 155 percent. Why the investors are not so willing to invest in the stock market? This research deals with existence of equity premium puzzle in Tehran Stock Exchange. Therefore, the Total Price Index of exchange market is considered as a risky asset and the return on long-term (5 years) deposit is a proxy for risk free asset. Data is monthly and covers the first month of 1380 (Persian Calendar) to the beginning of the second month of 1391 (equivalent to Aug 2010 to Jan 2013); which is converted to real term using monthly inflation rate....
Hyperbolic Branching Brownian Motion
, M.Sc. Thesis Sharif University of Technology ; Esfahani Zade, Mostafa (Supervisor)
Abstract
Hyperbolic branching Brownian motion is a branching diffusion process in which individual particles follow independent Brownian paths in the hyperbolic plane H2, and undergo binary fission(s) at rate λ > 0. It is shown that there is a phase transition in λ : For λ ≤ 1/8 the number
of particles in any compact region of H2 is eventually 0, w.p.1, but for λ > 1/8 the number of particles in any open set grows to ∞ w.p.1. In the subcritical case (λ ≤ 1/8) the set Λ of all limit points in ∂H2 (the boundary circle at ∞) of particle trails is a Cantor set, while in the supercritical case (λ > 1/8) the set Λ has full Lebesgue measure. For λ ≤ 1/8 it is shown that w.p.1 the Hausdorff dimension of Λ...
of particles in any compact region of H2 is eventually 0, w.p.1, but for λ > 1/8 the number of particles in any open set grows to ∞ w.p.1. In the subcritical case (λ ≤ 1/8) the set Λ of all limit points in ∂H2 (the boundary circle at ∞) of particle trails is a Cantor set, while in the supercritical case (λ > 1/8) the set Λ has full Lebesgue measure. For λ ≤ 1/8 it is shown that w.p.1 the Hausdorff dimension of Λ...
Enⅽrypteⅾ Traffiⅽ Anaⅼysis through Expⅼainabⅼe Ⅿaⅽhine Ⅼearning
, M.Sc. Thesis Sharif University of Technology ; Jalili, Rasool (Supervisor)
Abstract
Impressive progress in hardwares and developing encryption algorithms in last two decades are caused increase in using encryption protocols in network communications. In last decade, users use privacy preserving networks like Jap and Tor to protect their privacy. These networks protect users' data from eavesdroppers by using three-layer encryption and intermediate nodes between user and target website. Recent researches show that Deep Neural Networks can predict websites viewed by users with high accuracy. In other words, privacy preserving networks suffer from information leakage. In this research, we introduced some of the most powerful methods in encrypted traffic classification and then...
Analytical Nonlinear Solution of a Structurally Integrated Piezoelectric Trapizoidal Tapered Beam for Energy Harvesting
, M.Sc. Thesis Sharif University of Technology ; Hosseini Kordkheili, Ali (Supervisor)
Abstract
Tapering the beam along its length may lead to an increase in the voltage density of piezoelectric energy harvester. In this study, the energy harvester voltage with linear variable cross section is studied by developing an analytical method in both linear and nonlinear states. In linear mode, the results are compared with the experimental results. For the development of linear and nonlinear analytic relations, the Euler–Bernoulli beam and linear voltage variations in the thickness direction are used, and for the separation of variables, the mass normalized mode shapes has been used. The results of the linear analytical method are compared with the results of past research and experimental...
A FEM-BEM Model for Investigation of Fuel SlushingEffect on the Supersonic Wing Aeroelasticity
, M.Sc. Thesis Sharif University of Technology ; Haddadpour, Hassan (Supervisor)
Abstract
In the present work the stability analysis for the coupled aeroelasticity and fuel sloshing in supersonic wings is represented. The wing and store structure is modeled using the finite element method. The supersonic wing aerodynamic is modeled by the linear piston theory and store aerodynamic is modeled by the semi-stable slender body piston theory. Fuel sloshing in the store with desired geometry is modeled by the boundary element method. The coupled structure, aerodynamic and sloshing governing equations are drawn by using the Galerkin method and reduce order modeling teqnique for them and an effective numerical model was developed that is capable to analyze the stability for...
Gravity in Noncommutative Geometry
, M.Sc. Thesis Sharif University of Technology ; Esfahani Zadeh, Mostafa (Supervisor)
Abstract
In this thesis, the aim is to stating some of the noncommutative geometry(NCG) applications in formulating and describing the gravity. So, in the first chapter, we will work on some of metric aspects of NCG. In this chapter, we will review elements of the spin geometry, specifically we will define the Dirac operator which is the most important object in this thesis. Then, we will try to find counterparts of some of Riemannian geometric notions like integral and distance in the NCG framework. We will define some notions such as noncommutative infinitesimals, Dixmier trace, Wodzicki residue, noncommutative integral and spectral triples. Then, in the second chapter, we will work on some of the...
Modification of carbohydrate polymers via grafting in air. 1. Ceric-Induced synthesis of starch-g-polyacrylonitrile in presence and absence of oxygen [electronic resource]
, Article Starch - Starke ; Volume 54, Issue 3-4, pages 140–147, April 2002 ; Zohurian Mehr, Mohammad J
Abstract
Monomer grafting, a unique technique for polysaccharide modification, is always performed under inert (e.g., N2) atmosphere. This work is the first report related to evaluating the possibility and efficiency of the grafting of acrylonitrile (AN) onto starch in presence of oxygen. Thus, corn starch (in both granular and gelatinized states) as well as soluble starch were grafted by AN using a ceric-carbohydrate redox initiating system. Graft copolymerizations were performed under nitrogen, air, and oxygen atmospheres at similar conditions. Grafting occurrence was verified using chemical and spectral proofs. The polymerization mechanism and kinetics were investigated by recording the...
Modification of carbohydrate polymers via grafting in Air. 2. Ceric-Initiated graft copolymerization of acrylonitrile onto natural and modified polysaccharides [electronic resource]
, Article Starch - Stärke ; Volume 54, Issue 10, pages 482–488, October 2002 ; Zohuriaan-Mehr, Mohammad J
Abstract
Acrylonitrile (AN) was grafted onto various natural and modified polysaccharides (i.e., gum arabic, gum tragacanth, xanthan gum, sodium alginate, chitosan, sodium carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose) by using ceric-carbohydrate redox initiating system. After overcoming practical problems, mainly from the high viscosity of the aqueous solutions of the different substrates, the graft copolymerization reactions were run either in air or in N2 atmosphere under similar conditions. Grafting was confirmed using chemical and spectral (FTIR) proofs. The reactions were kinetically investigated using semi-empirical expressions and time-temperature profiles. An anomalous...
Modeling of in Plane Behavior of Retrofitted Adobe Walls with Finite Element Method under Cyclic Loading
, M.Sc. Thesis Sharif University of Technology ; Bakhshi, Ali (Supervisor) ; Ghannad, Mohammad Ali (Co-Advisor)
Abstract
Statistical studies indicate the fact that in Iran, like many other developing countries, a significant percentage of buildings are made of traditional materials and most of them are adobe buildings especially in rural areas. Furthermore, geological data indicates that Iran is located in alps-Himalayas seismic zone and exposed by destructive earthquakes and adobe buildings suffer the most damages comparing with other type of the structures. According to these explanations, this research deals with adobe buildings behavior and provides solutions for reinforcing them and improving the seismic response of these buildings. These studies include numerical modeling with finite elements methods by...
Silica chloride/wet SiO2 as a novel heterogeneous system for the deprotection of acetals under mild conditions [electronic resource]
, Article Phosphorus, Sulfur, and Silicon and the Related Elements ; Volume 178:2667-2670, Issue 12, 2003 ; Pourjavadi, Ali ; Zolfigol, Mohammad Ali ; Bamoniri, Abdolhamid
Abstract
A combination of silica chloride and wet SiO2 was used as an effective deacetalizating agent for the conversion of acetals to their corresponding carbonyl derivatives under mild and heterogeneous condition
Effect of the ozonation pretreatment on biogas production from waste activated sludge of tehran wastewater treatment plant
, Article Biomass and Bioenergy ; Volume 152 , 2021 ; 09619534 (ISSN) ; Ghasemi, S ; Khosravi, A ; Vossoughi, M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
In this study, the ozonation impact on anaerobic digestion of wasted thickened activated sludge of Tehran wastewater treatment plant has been investigated. Regarding that, the thickened activated sludge, a final solid waste of treatment plants, was subjected to ozonation pretreatment to evaluate its characteristics. Three major sludge characteristics were considered for investigating ozonation effects on anaerobic digestion. A comparison of two different ozone doses, i.e., 0.05 and 0.1 gO3 g−1TS was performed for short-term (10 days) and long-term (30 days) sludge retention times. Furthermore, biogas production, sludge composition, dewaterability, and energy balancing, were studied during...
Distributed Fault-tolerant Computation for Massive Data
, M.Sc. Thesis Sharif University of Technology ; Maddah-Ali, Mohammad Ali (Supervisor)
Abstract
In this thesis we consider the problem of distributed computation by many processors.We mainly concentrate on matrix multiplication problem in this thesis because of its importance. A distributed system consists of N worker processors and one master processor. The master processor should distribute the computation between workers and after computation in each of them, collect the results. In this thesis, we are going to mitigate the effect of straggler processors by using coding methods. Straggler processors can cause delays in the computation time.In this thesis, we firstly introduce a method to multiply any number of matrices in each other. The proposed method occurred in one shot without...
Incomplete Reduction of Iron Ore in a Fluidized Bed Reactor
, M.Sc. Thesis Sharif University of Technology ; Halali, Mohammad (Supervisor)
Abstract
The main goal of current investigation was partial reduction of Fe2O3 available in Hematite-rich ore to Magnetite by Fludization Bed method. The reductive gas, CO, was produced by incomplete combustion of Acetylene and Airmixed in inappropriate ratio. X-Ray Diffraction and X-Ray Florescence analyses were implemented in order to conducting qualitative analysis of present phases before and after reduction of the ore. Quantitative analysis of the same phases was also conducted by Titration. The latter analysis revealed the precise magnitude of available iron in each of the oxide containing phases. The chemical composition of the reactor gas was also determined before and after reduction...
Sequential Competitive Facility Location In Continuous Geometric Space
, M.Sc. Thesis Sharif University of Technology ; Abam, Mohammad Ali (Supervisor)
Abstract
Abstract The problem of competetive facility location can be defined as follows: There are a number of customers in the form of points in space, and two players arrange a number of facilities in the form of points in space, given some limitations, respectively. Each customer’s connection to each facility has a cost for the customer and an advantage for the facility, and each customer wants to be connected to at most one of the facilities which has the lowest cost for him. The goal is to find the strategy of placing the facilities and determining the cost which the facility receives from the customer, in such a way that the player’s profit is maximised.In this thesis, we first sought to...