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    Fabrication and Investigation of Supercapacitors Based on Graphene Nanocomposites

    , Ph.D. Dissertation Sharif University of Technology Jokar, Effat (Author) ; Iraji Zad, Azam (Supervisor) ; Shahrokhian, Saeed (Supervisor)
    Abstract
    Development of renewable energy production from sun and wind and the development of hybrid electric vehicles seem to be integral components in modern societies in order to overcome the environmental pollution and reduce the use of fossil fuel sources. In such devices energy storage plays an important role and supercapacitor is one the important energy storage devices. Structure of supercapacitor electrodes has considerable effect on supercapacitor performance. Graphene as a 2D carbon structure can improve electrochemical properties of electrodes. Here three different hybrid structure of graphene have been realized. The high capacitance and cyclic stability of graphene nanosheets decorated... 

    Synthesis and Stability Evaluation of Single Enzyme Nanoparticles for Enzymatic Based Processes

    , Ph.D. Dissertation Sharif University of Technology Khosravi, Arezoo (Author) ; Vossoughi, Manoochehr (Supervisor) ; Shahrokhian, Saeed (Co-Advisor) ; Alemzadeh, Iran (Co-Advisor)
    Abstract
    Enzymes, the nanometric biocatalysts that play a key role in biochemical reactions of living cells and bio-organisms, offer various applications including biosensing, bioremediation and chemical synthesis. A simple bio-conjugation procedure to surround a single horseradish peroxidase (HRP) enzyme molecule with dendritic polyester macromolecules (Polyester-32-hydroxyl-1-carboxyl bis-MPA Dendron, Generation 5) was proposed in this project. The characterization of resultant nanoparticles entitled HRP dendrozyme, was performed by TEM, DLS, GPC and FTIR spectroscopy. The results showed that HRP nanoparticles were spherical in shape and have an average size of 14 nm in diameter. Furthermore,... 

    Investigating Electrochemical Behavior of Biosensor Based on Vertically Aligned Carbon Nanotubes

    , Ph.D. Dissertation Sharif University of Technology Gholizadeh, Azam (Author) ; Shahrokhian, Saeed (Supervisor) ; Iraji Zad, Azam (Co-Advisor) ; Mohajerzadeh, Shamsoddin (Co-Advisor) ; Vossoughi, Manoochehr (Co-Advisor)
    Abstract
    In this research we focus on fabrication, characterization and performance of biosensors based on vertically aligned carbon nanotubes. Carbon nanotubes have been used as high density carbon nanotubes and nanoelectrode array. Carbon nanotubes have been grown using plasma enhanced chemical vapor deposition method. Characterization and performance of biosensors have been studied by cyclic voltammetry and electrochemical impedance spectroscopy methods.
    The mediator-less glutamate biosensor is prepared based on covalently attached glutamate dehydrogenase on vertically aligned carbon nanotubes. The biosensor has a low detection limit of 57 nM, two linear range of 0.1-20 µM with sensitivity of... 

    Design of Plasmonic Systems for Nanobiophotonic Applications

    , Ph.D. Dissertation Sharif University of Technology Shahmansouri, Afsaneh (Author) ; Rashidian, Bizhan (Supervisor) ; Vosoughi, Manouchehr (Supervisor) ; Shahrokhian, Saeed (Co-Advisor)
    Abstract
    In this thesis periodic plasmonic nanostructures are studied for detection of biological specious. The behavior of metal nanostructure arrays under normal incidence has been widely reported. However, simulation of periodic dispersive structures under oblique incidence requires newer formulations. Formulations, and algorithms based on modified split-field finite-difference time-domain (SF-FDTD) method are introduced, permitting analysis of metallic nanostructures arrays under oblique incidence. These novel algorithms are practically implemented on a parallel processing system based on graphics processing unit (GPU). Test and verification of these formulations are done by analyzing referenced... 

    Growth of Polymer/TiO2 Nanostructures by Layer-by-Layer Self Assembly Method as Electrodes of Photoelectrochemical Cells

    , Ph.D. Dissertation Sharif University of Technology Rahman, Masoud (Author) ; Taghavinia, Nima (Supervisor) ; Shahrokhian, Saeed (Co-Advisor)
    Abstract
    Dye sensitized solar cells (DSCs) are among the 3rd generation solar cells which their mechanism of light absorption is similar to chlorophyll in green leafs and is based on photo-excitation of dyes. The electron-hole pairs of photo-excited dye separate at the interface of mesoporous semiconductor-dye-electrolyte. One of the approaches to increase the light path length and therefore the light harvesting efficiency in DSC is the addition of light scatterers inside the mesoporous semiconductor (photoanode).In this research, nanoparticulated hollow TiO2 fibers are introduced as novel light scatterers in DSCs with simultaneous light scattering, light trapping and high surface area. Light... 

    Design and Implementation of Near Field Excitation System for Spectroscopy of Biological Species

    , Ph.D. Dissertation Sharif University of Technology Sasanpour, Pezhman (Author) ; Rashidian, Bizhan (Supervisor) ; Vossoughi, Manouchehr (Supervisor) ; Shahrokhian, Saeed (Co-Advisor)
    Abstract
    The main goal of this project is analysis, design and implementation of scanning near field optical system for detection of biological species. The activities fall in two main category. Theoretical and experimental. In theoretical part, after studying different models describing near field interaction, we have developed software for computationally analysis of nonlinear interaction of light with nanostructures, considering third order nonlinear susceptibility and dispersion behavior of permittivity for metallic nanostructures. The software implements three dimensional finite difference time domain (FDTD) method for analysis of interaction of electromagnetic wave with matter. In developed... 

    Simulation of a PEM (Positron Emission Mammography) System by GATE

    , M.Sc. Thesis Sharif University of Technology Reshtebar, Niloofar (Author) ; Sohrabpour, Mostafa (Supervisor) ; Setayeshi, Saeed (Co-Advisor)
    Abstract
    Breast cancer is the second leading cause of cancer death among women. Mammography is considered the “gold standard” in the evaluation of the breast lesions from an imaging perspective. But this modality has limitations. Completed studies are used to overcome these limitations. The Positron Emission Mammography (PEM) is the one of these complementary methods. PEM imaging is a molecular imaging modality for the diagnosis of breast cancer. In this thesis, a commercial PEM system as Naviscan PEM has been simulated using the GATE program. This system consists of two parallel planes of detectors, each detector consists of 12 blocks with 6 × 2 array and each block consists of 169 crystals with 13... 

    Modeling of Two Phase Flow in Porous Media with Heat Generation

    , Ph.D. Dissertation Sharif University of Technology Taherzadeh Fard, Morteza (Author) ; Saidi, Mohammad Saeed (Supervisor) ; Ghofrani, Mohammad Bagher (Co-Advisor)
    Abstract
    The main purpose of this work is investigation of coolability of a boiling debris bed. The main governing equations are derived using volume averaging technique. From this technique some specific interfacial areas between phases are appeared and proper relations for modeling these areas are proposed. Using these specific areas, a modification for the Tung/Dhir model in the annular flow regime is proposed. The proposed modification is validated and the agreements with experimental data are good. Finally, governing equations and relations are implemented in the THERMOUS program to model two-phase flow in the debris bed in the axisymmetric cylindrical coordinate. Two typical configurations... 

    Exact Simulation of Varian Clinac 2100C/D with Use of Phase Space file and Representation of Appropriate Source Model for Clinical Applications

    , Ph.D. Dissertation Sharif University of Technology Ezzati, Ahadollah (Author) ; Sohrabpour, Mostafa (Supervisor) ; Rabi Mahdavi, Saeed (Co-Advisor)
    Abstract
    MC Simulation is considered to be one of the most accurate methods for transport of radiation in various media. Computational speed is the limiting factor to apply the MC method in clinical settings. One of the methods to increase the speed in MC simulations is the use of phase space file (PSF). PSF is generated by transporting the particles through the linear accelerator head. The characteristics of these particles crossing a reference plane are stored in the PSF file. The PSF can be used in subsequent simulations as a radiation source. The use of PSF is effective but has a drawback of having latent variance. Latent variance is a problem inherent in using phase space files. Latent variance... 

    Experimental Investigation of Fretting Fatigue of Titanium Specimens Made by Additive Manufacturing Method

    , M.Sc. Thesis Sharif University of Technology Sajjad Houshmand (Author) ; Adibnazari, Saeed (Supervisor)
    Abstract
    Additive manufacturing (AM) has gained significant attention in recent years as a novel approach to fabricate three-dimensional parts. Its advantages, including high speed, low-cost production for small-scale batches, and greater design freedom, have made it a competitive alternative to traditional manufacturing methods. However, the application of AM for components subjected to fretting fatigue requires careful evaluation. Fretting fatigue is a major cause of failure in turbines, particularly at the contact interface between turbine blade roots and disk. In this study, the influence of AM and post-processing treatments on the fretting fatigue life of Ti-6Al-4V alloy was investigated. Five... 

    An Analytical and Experimental Investigation of the Vibration Characteristics of a Sandwich Cylindrical Shell with Electrorheological Fluid

    , Ph.D. Dissertation Sharif University of Technology Shah Ali, Pooriya (Author) ; Haddadpour, Hassan (Supervisor) ; Shakhesi, Saeed (Co-Supervisor) ; Mohammad Navazi, Hossein (Co-Supervisor)
    Abstract
    In this thesis, we investigate the theoretical and experimental vibrations of a cylindrical shell with an electrorheological core. Magnetorheological and electrorheological fluids are the most suitable materials used in smart structures and have various applications in the automotive, aerospace, civil engineering, medical engineering and robotics industries. We use starch particles and silicone oil to make electrorheological fluid. Then we make a sandwich beam with an ER core and extract the modal parameters of the structure using the modal test. Using the ASTM standard, we estimate the shear modulus of the fabricated ER fluid. In the following, based on the equations developed for the... 

    Investigation and Detection of Cracks for Health Monitoring of Concrete Structures Using Computer Vision

    , M.Sc. Thesis Sharif University of Technology Shojaei, Masoud (Author) ; Adibnazari, Saeed (Supervisor)
    Abstract
    Structural Health Monitoring (SHM) of civil infrastructures is of paramount importance in ensuring the safety and reliability of these structures. SHM involves the use of sensors and data analysis techniques to continuously monitor the structural condition of infrastructure, detect damage or degradation, and provide insights for maintenance and repair. Concrete cracks are one of the most common and critical types of damage in civil infrastructure, which can compromise the structural integrity and safety of the infrastructure if left undetected and untreated. Therefore, the development of effective and efficient crack detection techniques using computer vision and machine learning can... 

    Fretting Fatigue Crack Initiation Life Prediction Model in a Dovetail Joint of a Compressor

    , Ph.D. Dissertation Sharif University of Technology Badrikouhi, Ehsan (Author) ; Adibnazari, Saeed (Supervisor)
    Abstract
    Fretting fatigue is one of the main factors leading to failure in structures that have components temporarily connected to each other. The occurrence of fretting at the connection region of a structure under cyclic loading is inevitable, and only various methods can delay its occurrence or minimize the damage resulting from it. Fretting is dependent on various factors, and this has made previous studies unable to lead to a unified approach for predicting the fretting fatigue crack initiation life. In this thesis, after reviewing previous studies, a proving ring is designed for fretting fatigue testing. In the next step, fretting fatigue tests using the bridge-type method are performed on... 

    Bayesian Modeling of Road Surface Roughness Characteristics for Fatigue Damage Assessment

    , M.Sc. Thesis Sharif University of Technology Mobassrfar, Yasin (Author) ; Adibnazari, Saeed (Supervisor) ; Shariyat, Mohammad (Supervisor)
    Abstract
    Road roughness-induced vibrations are the main source of fatigue damage accumulation in vehicles. Hence, road surface profile modeling and simulation are of high importance when it comes to vehicle fatigue damage assessment. This research focuses on uncovering the statistical distributions that describe the characteristics of road loads that affect fatigue damage accumulation. Particle filtering is deployed to estimate the log-volatility of the road surface profile by assuming a random walk behavior for the hidden log-volatility. The skew-normal distribution with three parameters is fitted to the estimated log-volatility. The inferred parameters are used for synthesizing artificial road... 

    Detection and Evaluation of Damage in Concrete Structures Using Data-Driven Methods

    , M.Sc. Thesis Sharif University of Technology Ataei, Saeed (Author) ; Adibnazari, Saeed (Supervisor)
    Abstract
    Infrastructure maintenance is one of the important tasks that require the detection and classification of the condition of their components. One of the main challenges in identifying damage in concrete structures is the speed and accuracy of object detection methods. In this research, vision-based deep learning methods have been implemented to detect and analyze damages in concrete structures. To better evaluate this method, the dataset used in this research is a combination of the three datasets used in researches, which includes 400 pictures of cracks and spalls. This dataset is first augmented using different techniques, then with YOLOv7 instance segmentation and Mask R-CNN algorithms,... 

    Fatigue Life Investigation of Titanium Specimens Fabricated by 3D Printers

    , M.Sc. Thesis Sharif University of Technology Dehghan Manshadi, Amir (Author) ; Adibnazari, Saeed (Supervisor)
    Abstract
    In various industries such as aerospace, biomedicine and automobile manufacturing, they seek to manufacture light parts with complex geometry and acceptable mechanical properties. Additive manufacturing processes have gained a special place in the field of rapid prototyping, reverse engineering, mold production, etc. brought It is very important to know the mechanical properties, especially the fatigue behavior of the parts obtained by this method. In this research, the stress-fatigue life graph of parts made of Ti-6Al-4V (grade 5), which is one of the most widely used alloys in aerial structures, was extracted by selective laser melting. For this purpose, several standard fatigue test... 

    Durability Investigation and Fatigue Life Prediction Modelling for Pre-orroded AZ31 Alloy

    , Ph.D. Dissertation Sharif University of Technology Shams Arjmand, Madjid (Author) ; Adib Nazari, Saeed (Supervisor)
    Abstract
    This research explored the corrosion effect of NaCl solution on the surface quality of AZ31 magnesium alloy. Cubic-shaped specimens were immersed in standard 3.5% NaCl solution for 1, 2, 3, and 4 hours. The size of corrosion pits, fatigue crack propagation area, and surface topology were characterized. Fatigue tests were carried out on pre-corroded AZ31 specimens under different stress amplitudes. The correlation between the corrosion time and the virtual crack size was obtained. The virtual crack size is a new parameter that can relate the corrosion to the fatigue life. A new model was proposed to map the surface topology on the virtual crack size of pre-corroded AZ31 magnesium alloy. The... 

    Surface Treatment Effects on Fretting Fatigue Map of a Titanium Alloy

    , M.Sc. Thesis Sharif University of Technology Shariati Nejad, Ali (Author) ; Adib Nazari, Saeed (Supervisor)
    Abstract
    In contacts, the presence of both variable loading and low-amplitude movements causes a kind of fatigue in these components called FRETTING FATIGUE. fretting fatigue has reduced the life of parts. Due to the high cost of replacing some parts in case of failure, it is necessary to take effective measures to delay this exhaustion. One of the effective solutions that can be applied is the use of coating and surface treatments in the contact areas. In this research, first, the fretting fatigue maps of Ti-6Al-4V alloy have been calculated and drawn according to the recommendations of the ASTM standard by using finite element methods. In the next step, by using experimental experiments, the damage... 

    Experimental Investigation, Failure Analysis and Life Extension of Engine Cylinder Liners

    , M.Sc. Thesis Sharif University of Technology Saeedi, Meysam (Author) ; Adib Nazari, Saeed (Supervisor) ; Karimzadeh, Ardavan (Supervisor)
    Abstract
    A Cylinder Liner is one of the most important functional parts that gives a wear protective surface of cylinder block for piston and piston rings. Liners are used in automotive, ships, power aircrafts, and power generation units and the most load carrying part in internal combustion engine. Liners are subjected to various stresses during the engine working status. The stresses which act on cylinder liner are stress due to action of gas pressure and heat. Result of that stresses, wear developed inside of liner and internal or external cracking of cylinder liner takes place. In this paper, complete thermo-mechanical analysis of cylinder liner and failure mechanisms detected in alloyed cast... 

    Investigation and Analysis of the Coating Effect on the Contact Pressure and Slip Amplitude in Fretting Fatigue of a Compressor Blade Root

    , M.Sc. Thesis Sharif University of Technology Amini Chehragh, Hassan (Author) ; Adib Nazari, Saeed (Supervisor)
    Abstract
    In many industrial devices and machines, variable loading is applied to the parts, which will lead to fatigue in these parts. Most of these components are in contact with other components, and when the device is operating, low-amplitude movements occur at the contact point. Variable loading conditions and low-amplitude movements at the point of contact can cause failure on parts called FRETTING FATIGUE. This type of failure occurs in many aerospace components, such as where the compressor blade roots connect to the disc. In recent years, many failures due to fretting fatigue has been reported, which has made the need to take solution to prevent this type of failure more and more obvious. One...