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    Fabrication, Visualization and Calibration of a Novel TEM Microactuator

    , M.Sc. Thesis Sharif University of Technology Takht Abnousi, Marjan (Author) ; Alasti, Aria (Supervisor)
    Nowadays precise nano positioning plays an important role in micro systems. Precise positioning at nano scale plays a basic role in nano science such as micro -robotics, solid state physics and photonics. Manipulating matter in a molecular scale creates a dramatic change and restruturing in macro scale engineering. During this research a novel TEM micro actuator is designed and fabricated based on calibration criteria. This structure was fabricated with SOI wafer (silicon on insulator) in micro scale level for the first time in Iran. This compliant consists of 12 TEM actuators end in 3DOF (In-plane) motion. The new micro actuator operates based on the thermal expansion due to voltage. Each... 

    Fabrication of A Compliant Based 6-DOF Micro Actuator

    , M.Sc. Thesis Sharif University of Technology Akrami, Mohammad Reza (Author) ; Alasty, Areya (Supervisor)
    Currently, precision positioning plays a pivotal role in technology. The need for accurate positioning in applications such as robotics, optoelectronics and micro and nano technology increases day by day. To begin with, we wanted to make a miniature prototype of a micro actuator but in this regard, we are faced with several problems. Some major problems were the high cost of this prototype plus the fact that we did not have the necessary equipment with acceptable resolution for making such a system, so we decided to decrease the scale and build it in micro scale which is accessible for us. The main idea and design of this micro actuator is by Mrs. Akbari. During this project, the researcher... 

    Fluoride Removal from Sludge's of Evaporation Lagoons of Isfahan’s UCF Plant

    , M.Sc. Thesis Sharif University of Technology Khayambashi, Afshin (Author) ; Samadfam, Mohammad (Supervisor) ; Firouz Zare, Mahmoud (Co-Advisor) ; Ghasemi, Mohamad Reza (Co-Advisor)
    Nuclear energy is one of the most important sources of energy from the economical point of view and also in terms of cleanliness and safety. Hence, strategically, uranium is one of the most basic elements of the earth and nowadays, the importance of this element is more marked due to the nuclear industry developement. Therefore, uranium recovery from the wastes generated during nuclear fuel production in Isfahan’s uranium conversion plant- in which yellow cake is converted to uranium hexafluoride- is quite pivotal. In this experimental research, we have to remove Fluoride from waste after dissolution by several methods like precipitation. After that uranium is extracted from the sludge of... 

    Investigation the Machinability of Al/SiC Composite

    , M.Sc. Thesis Sharif University of Technology Rahiminasab, Jafar (Author) ; Kouchakzade, Mohammad Ali (Supervisor) ; Yoosafi, Reza (Supervisor)
    Metal matrix composites (MMCs) have received considerable attention due to their excellent engineering properties, but their poor machinability has been the main deterrent to their substitution for metal parts. The hardness and abrasive nature of reinforcement phase causes rapid tool wear during machining and, consequently, high machining costs. This paper discusses an experimental investigation on the machinability of Al-SiC particulate metal matrix composite produced by powder metallurgical process with , and %SiC. Continuous dry turning of round composite bars using titanium carbide inserts has been selected as the test method. The influence of machining parameters, e.g. cutting speed,... 

    Efficient Routing Architectures for Reconfigurable Devices

    , Ph.D. Dissertation Sharif University of Technology Seifoori, Zeinab (Author) ; Asadi, Hossein (Supervisor)
    Due to reduced Non-Recurring Engineering (NRE) costs, shorter time to market, design flexibility, and reprogramming capability of Field-Programmable Gate Arrays (FPGAs) as compared to Application-Specific Integrated Circuits (ASICs), FPGAs has been raised as a suitable substrate for implementation of digital systems. However, the high flexibility of reconfigurable devices leads to great power consumption, chip area, and reliability difference between ASICs and FPGAs. In addition, with the advent of multi-tenant FPGAs in cloud computing environments, it has been shown that crosstalk side-channel attack, which can be used by a malicious IP to leak valuable information, has become an urgent... 

    A Power-efficient Architecture for SRAM-based FPGAs Using Reconfigurable Hard Logic Design in Dark Silicon Era

    , M.Sc. Thesis Sharif University of Technology Ebrahimi, Zahra (Author) ; Asadi, Hossein (Supervisor)
    Significant increase of static power with downscaling of transistor feature size and threshold voltage has lead to the end of Dennard scaling. This obstacle has put a Power Wall to further integration of CMOS technology in Field Programmable Gate Arrays (FPGAs). An efficient solution to cope with this obstacle is to apply power gating to the inactive fractions of a single die, referred to as Dark Silicon. Previous studies employing power gating on SRAM-based FPGAs have primarily focused on using large-input Look-up Tables (LUTs) which suffer from poor logic utilization, and subsequently, limiting the benefits of power gating techniques. This thesis proposes a heterogeneous Power-Efficient... 

    Mapping and Scheduling Applications onto Multi-Core Chip-Multiprocessors in Dark-Silicon Era

    , M.Sc. Thesis Sharif University of Technology Hoveida, Mohaddeseh (Author) ; Sarbazi Azad, Hamid (Supervisor)
    Growing transistor counts, limited power budgets, and the breakdown of voltage scaling are currently conspiring to create a utilization wall that limits the fraction of a chip that can run at full speed at one time. This concept is the basis of the Dark Silicon definition. To address this issue, it is needed a structure to guaranty Limited power budget and obtain sufficient flexibility and performance for different applications with variety communication needs. Regarding to this structure, our aim is to present a platform for Networks-on-Chip that uses clustering and resource sharing among cores. Moreover, as task mapping on processing elements in NOCs is one of the most effective way to... 

    Processor Allocation for Future Multi-Core Chip-Multiprocessor

    , M.Sc. Thesis Sharif University of Technology Agha Ali Akbari, Fatemeh (Author) ; Sarbazi Azad, Hamid (Supervisor)
    Since 2005, processor designers have increased core counts to exploit Moore’s Law scaling, rather than focusing on single-core performance. For decades, this approach provides desired performance for parallel and multithreaded workloads. On the other hand, rising of utilization wall limits the number of transistors that can be powered on in chip and result in a large region to be dark. So, same as before trend for performance scaling in future multi processor, an appropriate architecture is essential. There are some structures for this era which used specialization approach to cope with the limited power budget. Therefore, in this thesis, we propose a general-purpose platform that provides... 

    Surface and Interface Effects on the Elastic Fields of an Edge Dislocation Inside a Silicon Nanotube with Thin Siox Coating

    , M.Sc. Thesis Sharif University of Technology Azizi, Pegah (Author) ; Mohammadi Shodja, Hossein (Supervisor)
    The exact analytical elastic fields within a double-walled silicon nano-tube with a thin layer of SiOx coating associated with surface/ interface effects as well as the classical theory of elasticity due to the presence of an edge dislocation with an arbitrary Burger’s vector and position inside of the silicon is determined via complex potential function method. Stress contours within surface elasticity and classical theory are given, and both theory results are compared. Then, the effects of surface Lamé Constants, magnitude and direction of Burger’s vector, shear modulus, nano-tube size, and position of the edge dislocation on the distribution of stress components are illustrated, and the... 

    First Principles Studies of Mechanical, Physical, and Electronic Properties of a-Si - also, Diffusion of a Self-interstitial Atom in an Ultra-thin fcc Film Via Lattice Statics

    , Ph.D. Dissertation Sharif University of Technology Tabatabaei, Maryam (Author) ; Mohammadi Shodja, Hossein (Supervisor)
    By employing first principles density functional theory-based (DFT) molecular dynamics (MD), the influences of dangling and floating bonds as well as distorted tetrahedral bonds are studied on the mechanical, physical, and electronic properties of amorphous Si (a-Si). For further examination of the effects of these geometrical defects, two distinct amorphous samples, namely as-quenched and annealed are generated and examined. To verify the validity of the representative cells, the obtained radial distribution function, pair correlation function, and cohesive energy are compared with those corresponding results presented in the literature. Moreover, the surface energy is calculated at final... 

    Multi-sclae Modeling for Determination of Thermal Properties of Silicon Nanostructures Via Molecular Dynamics (MD) and Finite Element Method (FEM)

    , Ph.D. Dissertation Sharif University of Technology DorMohammadi, Hossein (Author) ; Khoei, Amir Reza (Supervisor)
    The band gap offset is an effect of coordination numbers (CNs) of atoms reduction at the edge of transversal cross-section Si nanowires (SiNWs) which would be of increasingly important for greater shell-core ratio sections. In this paper, a hierarchical multi-scale modeling has been developed to simulate edge effect on the band gap shift of SiNWs due to geometry effect induced strain in the self-equilibrium state. Classical Molecular Dynamics (MD) approach and Finite Element Method (FEM) are used in the micro (atomic) and macro scale levels, respectively. Using the Cauchy-Born (CB) hypothesis as a correlator of continuum and atomic properties, the atomic positions are related to the... 

    Chemomechanical Modeling of Silicon Electrode in Lithium-Ion Battery by Considering the Effects of Large Plastic Deformation and Strain Rate

    , Ph.D. Dissertation Sharif University of Technology Bagheri, Afsar (Author) ; Naghdabadi, Reza (Supervisor) ; Argavani Hadi, Jamal (Supervisor)
    In Li-ion batteries, large volume changes of electrodes with high capacity, such as silicon electrodes during charging and discharging processes (insertion/extraction of lithium into/from the electrode), lead to restrictions on the use of this type of electrode. Given the very high capacity of silicon, predicting and modeling the behavior of silicon electrodes during electrochemical cycles is important and is also addressed in this thesis. First, using the theory of linear elasticity, relations are proposed that couple the diffusion of particles with small elastic deformation. The effect of hydrostatic stress on diffusion and stresses is investigated in lithiation processes. Then, the... 

    Improvement of Polymer Composites Thermal Conductivity by Nanoparticles

    , M.Sc. Thesis Sharif University of Technology Kazemi Ranjbar, Sina (Author) ; Nouri Broujerdi, Ali (Supervisor)
    The new generation of electronic devices including 5G internet, wearable electronics, LED optoelectronics or cloud computing devices have higher power density as their computing power increases and their sizes reduce. The increase in power density leads to higher heat generation and consequently higher operating temperature which reduces their lifetime and reliability. In recent years development of novel solutions for electronic cooling has been persued. Thermal interface material that inserted between heat source and heat sink is the main component in electronic cooling. These materials consists of a polymeric base that filled with highly thermally conductive solid particles. By emergence... 

    Analysis of Ratcheting in Elastic-plastic Behavior of Li-ion Battery Electrodes

    , M.Sc. Thesis Sharif University of Technology Hashemi, Mohammad Ali (Author) ; Naghdabadi, Reza (Supervisor)
    Among the various materials, silicon anodes have the highest lithium absorption in lithium-ion batteries. But this high lithium absorption capacity can cause 300 percent volume expansion and large stresses. Experimental observations show that charge and discharge cycles may cause plastic deformation in some parts of the electrode particle. On the other hand, there is a possibility of a ratcheting phenomenon due to changing in elastic properties of the electrode material during the charging and discharging processes. However, this phenomenon has not been reported for silicon spherical electrode particles yet.This study aims to model the elastic-plastic behavior of silicon spherical electrode... 

    Investigation of Thermal Stress Effect on The Performance of Thin Film Solar Cells Using Finite Element Method

    , M.Sc. Thesis Sharif University of Technology Namvar, Arman (Author) ; Naghdabadi, Reza (Supervisor) ; Sohrabpour, Saeed (Supervisor)
    Thin film solar cells have low efficiency compared to crystalline silicon solar cells; however, they are low-cost and flexible. In manufacturing these solar cells, thin films are deposited at high temperatures (higher than 200℃) on a thick metal, plastic, or glass substrate using sputtering and plasma enhanced chemical vapor deposition (PECVD) methods. Since the thin films and substrate have different thermal expansion coefficients, cooling the system from deposition temperature to room temperature induces thermal residual stresses in both the films and substrate. In addition, these stresses, especially those induced in the amorphous silicon layer can change the carrier mobility and band gap... 

    Investigation And Fabrication Super Hydrophobic Coating On Building Facades

    , M.Sc. Thesis Sharif University of Technology Bayat Mazlaghani, Mohammad (Author) ; Afshar, Abdullah (Supervisor)
    According to the creation of high-rise buildings and structures due to the increase in urbanization and population concentration in cities and attention to the beauty of these structures and the impact of this beauty on the morale of urban people, owners or municipalities costs a lot of money for cleaning the building facade every year. On the other hand, removing contaminants from high-rise buildings facades is difficult and lifethreatening. Today, with the advancement of science and the use of self-cleaning super hydrophobic coatings, many of these costs, as well as threats to life, can be prevented. On the other hand, protection of ancient structures as a cultural capital of a country,... 

    Evaluation of Microstructure and Wear Behaviour of Nicrbsi Composite Coating Deposited by Atmospheric Plasma Spray and Plasma Transferred Arc on Steel Substrate

    , M.Sc. Thesis Sharif University of Technology Rashid, Majid (Author) ; Movahedi, Mojtaba (Supervisor) ; Kokabi, Amir Hossein (Supervisor)
    Nowadays, in many industrial applications, protecting surfaces has become necessary. This research attempted to create a coating resistant to the wear of NiCrBSi with the help of the atmospheric plasma spray and the process of plasma Transferred Arc on the substrate of the simple carbon steel. Also, in order to study the effect of compositing on hardness and abrasive properties of the APS coatings, NiCrBSi powder was strengthened with 25 weight percent of Titanium Carbide particles so that the NiCrBSi-25TiC composite coating could also be created. According to the nature of the APS process, the substructure of this coating always has some porosity and layered structure, and the connection of... 

    Using FSP Method to Create Composite and Surface Foam with Distribution Gradient of Particles and Porosity as FGM and Study of Physical and Mechanical Properties

    , M.Sc. Thesis Sharif University of Technology Karimi, Mahdi (Author) ; Akbarzadeh, Abbas (Supervisor)
    Nowadays, the tendency to use Al/SiC composites with FGM structure has increased in the automotive and aerospace industries, because in this type of composite, the properties can be gradually changed in the direction of thickness. For example, one composite surface is used as a wear-resistant or high-temperature-resistant coating, and the other surface can be welded, has high thermal conductivity, or has a good toughness. In recent years, methods have been used to make surface composites, most of which are in the molten state and at high temperatures. In this case, the reactions between the compounds can not be easily controlled and the possibility of the formation of undesirable or... 

    Enhanced Superhydrophobic and Photocatalytic Characteristics of Tio2 Hybrid Nanocoating for Self-cleaning Applications

    , M.Sc. Thesis Sharif University of Technology Hajizadeh, Arman (Author) ; Mohammadi, Mohammad Reza (Supervisor)
    Many researches have been made on super hydrophobic and photocatalyst nano coatings in the last decades as a solution to some environmental issues. Among all semiconductors chosen for this property, titanium dioxide is often used because of it's low cost, ease of accessibility and stability in different chemical circumstances to break up organic pollutions. Mixing this property of TiO2 with hydrophobic manner of SiO2 causes a superhydrophobe & photocatalyst nano coating. Doping TiO2 with another semiconductor may also improve photocatalytic behavior of coating by increasing surface area of reaction or decreasing the band-gap.In this research TiO2-SiO2 hybrid nano coating is made via... 

    Preparation of Cu-MoSi2 Nanocomposite by Mechanical Alloying and Investigation of Properties

    , M.Sc. Thesis Sharif University of Technology Khavas, Elham (Author) ; Pourazarang, Kazem (Supervisor) ; Abachi, Parvin (Supervisor)
    In this study, to synthesize molybdenum disilicide nano powder, mixed powder of Mo and Si were ball milled for 15, 30, 45 and 55 hours. By the results of the analyses, milled powders for time intervals of 55 hours were heat treated to release the stresses. This process was carried out in an argon vacuum tube furnace at 1000˚C for 1 hour. XRD analysis was carried for sample. Finally, MoSi2 powder with 86.62 nm crystallite size was used as reinforcement. Cu-MoSi2 composite powder with 2, 3, 5wt% were produced. Cu-MoSi2 with 2wt% reinforcement was milled for 60 hours. Powder composite was compacted by Spark Plasma Sintering . Microstructure of composite was investigated by scanning electron...