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    An Investigation into the mechanical properties and micro-structure of Aluminum tube after Severe Plastic Deformation and Annealing

    , M.Sc. Thesis Sharif University of Technology Zangiabadi, Amir Ali (Author) ; Kazeminezhad, Mohsen (Supervisor)
    Abstract
    Several SPD methods have been invented for processing rods and sheets, and their physical and mechanical properties have been investigated so far. The materials processed by these methods have not been industrialized thoroughly. Moreover, in previous investigations, few works have been carried out on tubular types of materials. Thus, in this study, aluminum tube goes through a tubular channel in order to achieve different values of strains. This method is named Tube Channel Pressing. The mechanical and microstructural investigations on aluminum tubes which have been processed up to 5 passes shows that ultimate strength increases 1.7 times and sub-grains size reaches to 360 nm. Applying final... 

    Development of a novel severe plastic deformation method for tubular materials: Tube Channel Pressing (TCP)

    , Article Materials Science and Engineering A ; Volume 528, Issue 15 , June , 2011 , Pages 5066-5072 ; 09215093 (ISSN) Zangiabadi, A ; Kazeminezhad, M ; Sharif University of Technology
    2011
    Abstract
    A new severe plastic deformation (SPD) method entitled Tube Channel Pressing (TCP) is proposed. In this study, the ability of TCP on strength improvement and grain refinement is assessed. This method is based on pressing a tube through a tubular channel die with a neck zone. Utilization of a mandrel fitted inside the tube prevents the crumpling of tube and preserves its initial dimension. Due to the symmetric design, after one pass, the die is rotated upside down and the second pass is applied by pressing the tube in inverse direction. Ultimate strength of a commercial purity aluminum tube after 5 successful passes is improved to 2 times of the initial strength. Analytical calculations and... 

    Computation on new deformation routes of tube channel pressing considering back pressure and friction effects

    , Article Computational Materials Science ; Volume 59 , June , 2012 , Pages 174-181 ; 09270256 (ISSN) Zangiabadi, A ; Kazeminezhad, M ; Sharif University of Technology
    2012
    Abstract
    Three deformation routes for recently invented severe plastic deformation (SPD) method named tube channel pressing (TCP) have been introduced in this paper. The effects of routes, back pressure and friction have been investigated on deformation behavior of commercially pure (CP) aluminum tubes. Utilizing finite element analysis provides a broader understanding of these effects through different deformation routes. Due to the large values of strains accumulated in TCP, modified Estrin-Tóth-Molinari-Brechet (METMB) constitutive model has been employed in finite element analysis program to consider a realistic flow stress of the material in TCP. Employing experimental procedures confirms the... 

    An AI Based Cryptocurrency Trading System

    , M.Sc. Thesis Sharif University of Technology Yasrebi, Amir Abbas (Author) ; Khayyat, Amir Ali Akbar (Supervisor)
    Abstract
    Cryptocurrencies are not only regarded as a trustworthy method of financial transaction validated by a decentralized cryptographic system as opposed to a centralized authority, but also as one of the most popular and lucrative forms of trade and investing. Predicting the price of a cryptocurrency is a challenging topic in time-series research. Its intricacy is due to the volatility and large swings of cryptocurrencies' price. The emergence of brand-new cryptocurrencies, which might present a profitable trading opportunity but lack sufficient historical data for technical analysis, prompted us to develop a trading strategy that could be applied universally. The forecast of the next timestep's... 

    Numerical Investigation of Dewetting of Evaporating thin Films over Nanometric Topography

    , M.Sc. Thesis Sharif University of Technology Akbarzadeh, Amir Mahdi (Author) ; Moosavi, Ali (Supervisor)
    Abstract
    Evaporation and condensation of thin films can rupture or stabilize thin film .We show that evaporation hastens dewetting of a thin film. Dewetting over nanometric downward step causes pinning of the contact line near the step. This phenomena is not permanent and after certain time that contact angle reaches to its critical value depinnnig happens. We also study the effect of the step size, contact angle, film thickness, slip and evaporation on the depinning time of the contact line. We show that depinnig time has a reverse relation with the rate of evaporation  

    Design and Implementation of Tunable Microwave Gain Equalizer

    , M.Sc. Thesis Sharif University of Technology Ahmadi, Amir Hossein (Author) ; Banai, Ali (Supervisor)
    Abstract
    Modern broadband microwave and millimeter-wave systems often struggle with excessive pass band ripple and negative gain slopes due to the loss of transmission lines such as coaxial cables, or ripples in the gain characteristic of broadband amplifiers. The common solution for this problem is using a gain equalizer to compensate for the intrinsic pass band variation with some extra loss in the band of interest in return.Designed equalizers often have a constant slope in their bandwidth. However, having ripples in pass band or in other words slope changing in some parts of the band is one of the issues that designers should deal with. In this thesis, after reviewing the previous works on the... 

    Design and Fabrication of a 1GHz Low phase Noise SAW Oscillator

    , M.Sc. Thesis Sharif University of Technology Mehri, Amir Ehsan (Author) ; Banai, Ali (Supervisor)
    Abstract
    For decades Crystal Oscillators (XO) have been the unequaled references for stable and low noise frequency sources. This leadership is due to their high Q-factor. The resonant frequency of such crystal resonator is inversely proportional to the thickness of the quartz disk (the resonant cavity) and is today limited , by physical manufacturing constraints , to about 150 MHz . in order to avoid such limitation , the solution is to start with an oscillator at higher fundamental frequency. SAW technology on quartz offers this opportunity . with SAW the resonant cavity size is not linked to the thickness of the substrate and resonant frequencies up to the GHz range are achievable. In this thesis... 

    Effect of Subsequent Drying and Wetting on Small Strain Shear Modulus of Unsaturated Silty Soils Using Bender Element

    , M.Sc. Thesis Sharif University of Technology Hashemi, Amir Hossein (Author) ; Khosravi, Ali (Supervisor)
    Abstract
    Evaluation of the seismic-induced settlement of an unsaturated soil layer depends on several variables, among which the small strain shear modulus, Gmax, and soil’s state of stress have been demonstrated to be of particular significance. Recent interpretation of trends in Gmax revealed considerable effects of the degree of saturation and hydraulic hysteresis on the shear stiffness of soils in unsaturated states. Accordingly, the soil layer is expected to experience different settlement behaviors depending on the soil saturation and seasonal weathering conditions. In this study, a semi-empirical formulation was adapted to extend an existing Gmax model to infer hysteretic effects along... 

    On Efficiency and Bandwidth Enhancement of Integrated Class-J Power Amplifiers

    , Ph.D. Dissertation Sharif University of Technology Alizadeh, Amir Reza (Author) ; Medi, Ali (Supervisor)
    Abstract
    Power amplifiers (PAs) are one of the key components in radio-frequency (RF) and microwave systems. In these systems, PAs must be highly efficient to simplify the thermal management and to enhance dc power requirements. Future systems, including WiMax, 4G, 5G, and beyond, will likely require larger bandwidths due to their wider spectral allocations caused by the extended bandwidth of baseband signals. Therefore, highly-efficient and broadband PAs are needed to be employed in these systems. To realize high-efficiencies over wide frequency ranges, class-J mode of operation was introduced by Cripps in 2009. Class-J mode of operation is capable of maintaining a high efficiency (78% in theory)... 

    Design and Implementation of a Voltage Controlled Oscillator For 77GHz Automotive Radar

    , M.Sc. Thesis Sharif University of Technology Kiavar, Amir Arsalan (Author) ; Medi, Ali (Supervisor)
    Abstract
    Wideband mm-wave radars are gaining popularity in automotive applications due to their superiority in harsh weather conditions, high distance resolution, precise velocity measurement, and superior spatial resolution. The primary purpose of this thesis is to design and implement a voltage-controlled oscillator for 77GHz automotive radar applications.Phase noise -as one of the most crucial specifications in VCO design- Phase noise improvement techniques as well as harmonic engineering methods are delineated. Also, an Ocean-based code for ISF simulation is introduced and developed to obviate the need for additional signal processing software so that simulation speed increases... 

    Analyzing Narrative Policy Framework of Innovation Policy in Development of Iran’s Innovation Ecosystem

    , M.Sc. Thesis Sharif University of Technology Vaezi, Amir Mohammad (Author) ; Maleki, Ali (Supervisor)
    Abstract
    The development of innovation ecosystems has become a global trend. These ecosystems have proven their importance to governments by having a significant impact on the creation of technology companies and the economic growth of the country. In Iran, too, for many years, efforts have been made under various headings to develop the innovation ecosystems. In this dissertation, based on the narrative policy framework, the existing policy narratives of innovation ecosystems development policy in iran between 2013-20 years in the case of startup ecosystem have been analyzed. After analyzing these data, it was found that the three main narratives of catch-up, wealth creation and infiltration, have... 

    Drug-Target Interaction Prediction with Deep Learning and Recommender Systems

    , M.Sc. Thesis Sharif University of Technology Nosrati, Amir Hossein (Author) ; Ghafourian Ghahramani, Amir Ali (Supervisor) ; Kavousi, Kaveh (Supervisor)
    Abstract
    A drug can be defined as a substance made to prevent disease, cure a specific symptom, relieve pain, and reduce anomalies in the body. The process of drug designing is so laborious, complex, costly, and time-consuming that chance of failure during the lab experiment stages is high. These challenges have persuaded researchers to find new usage for existing drugs, referred to as drug repurposing, with the main advantage of reducing cost, risk, and time. To this aim, computational methods have been applied to discover hidden pharmaceutical capabilities of drugs in terms of predicting whether a particular drug can interact with a particular protein.Graph Neural Networks (GNNs) have recently... 

    Fabrication of Oleophobic Coating

    , M.Sc. Thesis Sharif University of Technology Rahimi, Amir Mohammad (Author) ; Mousavi, Ali (Supervisor) ; Nouri Borujerdi, Ali (Supervisor)
    Abstract
    Wettability is the cause of many interactions today and is definitely effective in almost all processes where liquid and solid phases are in contact. Wetting controls by surface engineering can accelerate the process in the industry or improve the quality of daily life. Therefore, the fabrication of complex surfaces with a specific purpose and different wettability has attracted the attention of researchers. In this thesis, silica nanoparticles were synthesized to create roughness and reduce contact between surfaces and liquids at first. Then, using chemical compounds to reduce the surface energy, a transparent (94.20%) superhydrophobic and oleophobic coating was created on the glass. The... 

    The Effect of Ownership Structure and Board Composition as Corporate Governance Mechanisms on Coroporate Value

    , M.Sc. Thesis Sharif University of Technology Sadighian, Amir Hossein (Author) ; Mashayekhi, Ali Naghi (Supervisor)
    Abstract
    In this research we examine the effects of internal corporate governance mechanisms on shareholder value of 247 firms that were accepted in Tehran Stock Exchange. The main focus is on ownership structure and board composition. Owners with different identities affect shareholder value both directly and to some extent indirectly (through affecting board composition). We measured firm value using 2 different measures: relative growth of share price and market to book value of the firm. Controlling for industry effects, considering different levels of competitiveness, we find that private owners affect firm value more positively than governments and so do institutional investors more than... 

    Entropy Analysis and its Application in Interconnection

    , M.Sc. Thesis Sharif University of Technology Soltanian, Abbas (Author) ; Baniasadi, Amir Ali (Supervisor)
    Abstract
    Reducing interconnection costs on chip and power consumption are important issues in designing processors. In a processor, a significant amount of total chip power is consumed in the interconnection. The goal of this research is to find a way to reduce power consumption in the interconnection. In this project we propose a new data sending method in which an LZW-like compression algorithm is exploited to compress data before sending it over the interconnection. Then, the codes of the compressed data are sent through the interconnection in order to reduce the number of dynamic cycles. The simulation results show that using this method can reduce 52% of dynamic power consumption  

    Design and Implementation of a 1-2 GHz Ultra Low Phase Noise Phase Locked Loop using SPD

    , M.Sc. Thesis Sharif University of Technology Abedanzadeh, Amir Hossein (Author) ; Banaei, Ali (Supervisor)
    Abstract
    In this thesis first of all we investigate phase noise and it's generation factors. Then we design and implement an ultra low phase noise oscillator. To do this, an ultra low phase noise oscillator which is tunable in 1-2GHz with 100MHz steps will be designed. The outline of the circuit is as follows: at the first we design a VCO which is ultra low phase noise and mechanically tunable in 1-2GHz by means of rotation of a handle. Then a phase locked loop will be built with the help of an ultra low phase noise OCXO at 100MHz and one SPD1 which generates harmonics of OCXO's output frequency. For the next, design and implementation of a 1.6GHz oscillator with fixed output frequency has been done.... 

    Friction Stir Welding of Commercially Purity Titanium and its Effect on Microstructure and Mechanical Properties using Different FSW Tools

    , M.Sc. Thesis Sharif University of Technology Nasiri, Ali Mohamad (Author) ; Kokabi, Amir Hossein (Supervisor)
    Abstract
    The objective of this investigation was obtaining sound Friction Stir Welded (FSWed) Commercially Purity Titanium using suitable Tool’s Materials (for Shoulder and Pin) in order to be able to work in high temperature (>1000 ˚C) with great mechanical properties and minimum wear during process. Consequently, different materials and designs for Tool, such as High Speed Steel tool, Tungsten based tool, Tungsten Carbide (WC-Co) based tool and diverse tool geometry and designs like simple design, threaded design, fixed pin and inserted pin (adjustable pin) was used. The results demonstrated that using simple cylindrical WC-Co for pin and Tungsten for shoulder resulted in joints with the best... 

    Semi-Active Intelligent Control for an Offshore Steel Jacket Platform with Magnetorheological Damper Wave-Induced Forces

    , M.Sc. Thesis Sharif University of Technology Sarrafan, Atabak (Author) ; Khayyat, Amir Ali Akbar (Supervisor)
    Abstract
    Due to the inherent non-linear nature of the MR damper, an intelligent non-linear neuro-fuzzy control strategy is designed for control of wave-induced vibration of an offshore steel jacket platform equipped with MR dampers. In the proposed control system, a dynamic-feedback neural network is employed to model non-linear dynamic system and the fuzzy logic controller is used to determine the control forces of MR dampers. Required voltages and actual forces of MR dampers are obtained by use of two feedforward neural networks, in which the first neural network and second one act as the inverse and forward dynamics model of the MR dampers, respectively. The most important characteristic of the... 

    Design and Implementaion of a Web Application Honeypot

    , M.Sc. Thesis Sharif University of Technology Ali Akbarian, Amir Hossein (Author) ; Kharrazi, Mehdi (Supervisor)
    Abstract
    With the rapid growth of Internet popularity, web applications are growing in usage and complexity, and therefore, are attractive targets for attackers. Increasing number of services and amount of information stored in the Internet, stimulates attackers to focus on these kind of applications. On the other hand, security specialists are deploying different solutions to mitigate such threats. One of these solutions are Honeypot systems. In contrast with other security solutions, honeypots are not designed to defend against attackers directly. Honeypots, rather, are planned to gather data about what attackers do. This information can help security administrators to learn and understand... 

    The Effect of Partial Foundation Uplift on Seismic Performance of Structures

    , Ph.D. Dissertation Sharif University of Technology Jafarieh, Amir Hossein (Author) ; Ghannad, Mohammad Ali (Supervisor)
    Abstract
    It is well-known that the behavior of soil-structure systems can be well described using a limited number of non-dimensional parameters. This is the outcome of researches based on the premise that the foundation is bonded to the ground. Here, it is shown the concept can be extended to systems with foundation uplift. A set of non-dimensional parameters are introduced which controls the main features of uplifting systems. The super-structure is modeled as an equivalent single-degree of freedom system with elastic behavior mounted on a rigid foundation resting on distributed tensionless Winkler springs and dampers. The effect of foundation uplift on response of soil-structure systems are...