Sharif Digital Repository

In this study, for the first time, a comprehensive and online framework for active control of beams subjected to the moving mass is presented. In active control problems, comprehensive knowledge of system states is required to determine the control force, but it is not possible to measure all system states in practice with a limited number of sensors. In this regard, Kalman filters are introduced to control systems to help improve the performance of control systems as observers of system states. However, in the case of beams subjected to the moving mass, due to the moving nature of the passing mass, in addition to system states, it is also important to identify the input load. In previous... 

In this research, metal oxides and hydroxides with carbon materials and conductive polymers (CPs), as well as transition metal oxysulfide nanostructures (TMOS), hybrid of Tin oxide and sulfie and polyphasphate-reduced graphene oxide (PPO-RGO) have been used as an active electrode materials for supercapacitors. In the first section of thesis, Tiron and graphene oxide (GO) were used as an anionic dopants to increase the capacity and stability of polypyrrole (PPy). In order to increase the capacity of Tiron/PPy/GO nanocomposite, vanadium oxide (V2O5) was used. The Tiron/PPy/GO/V2O5 nanocomposite was deposited on a stainless steel (SS) as a substrate via one-step electrochemical deposition... 

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... 

In this thesis, composites of carbon nanotubes and carbon nanohorns with some transition element compounds such as cobalt sulfide, cobalt-based metal-organic framework, copper oxide, manganese dioxide, and gold nanoparticles were used to prepare modified electrodes for electrochemical sensors for measuring small amounts of pharmaceutical compounds such as Rifaximin, Molnopiravir, Atazanavir, Valacyclovir, and Moxifloxacin. In the first work, a combination of MWCNTs/MnO2 decorated with gold nanoparticles by electrochemical deposition method was used for the detection of Rifaximin (RFX). This sensor had a linear range of 0.75 to 200 μM with a detection limit of 0.25 μM and a sensitivity of... 

In the first part of this research, for the first time, we introduced a flexible high performance graphene-based supercapacitor using silver fiber fabric as the current collector. The silver fiber fabric offers remarkable advantages such as light weight, mechanical flexibility and ease of integration with electronic textiles, which well-suited for wearable energy storage devices. A new hybrid material of graphene-silver fiber fabric (rGO/SFF) was prepared through a facile electrophoretic deposition of graphene and being used as a binder-free flexible supercapacitor electrode. In order to obtain the optimum condition, the effect of deposition time was investigated and a duration time of 10... 

Oxygen gas has many applications and is used in respiration, welding, methanol production, steel industry, rocket fuel and most importantly fuel cells. Today, due to the environmental pollution caused by fossil fuels, the use of clean energy production methods such as fuel cells has received much attention. In hydrogen fuel cells, electrical energy is generated using oxygen and hydrogen gases through an electrochemical process. One of the common methods of producing these gases is electrolysis of water in which the kinetics of anodic reaction (oxygen evolution) have led to many researches in the field of improving metal and non - metal electrocatalysts, especially based on carbon... 

Recently, computer scientists and economists have defined many joint problems and cooperate widely in various areas. Importance of this interconnection is clear for everybody, now. New works have been conducted, nowadays, to use the daily - increasing web-based social networks in viral marketing for improving companies profits. The main problem which is proved to be NP-Complete in this context is about discovering k most influential nodes in a network. In this dissertation, we generalize the problem to a group-based version and we we use group-based advertising to achieve our main goal. A new algorithm called Group-Based Diffusion technique is proposed in this thesis for solving this problem... 

Origin-destination (OD) matrix is one of the most important sources of information used in planning and management of transportation networks. Estimation of a precise OD matrix is a fundamental component for enabling the administrative authorities to optimize the use of their transportation network. Traditionally, urban planners use direct approaches including household questionnaires to estimate OD matrices. These methods are time-consuming and costly. Strategies that are more recent like Bluetooth, Wi-Fi, and RFID scanners and detectors include deficient precision and the additional cost of accessories. Exploiting GPS technology in spite of its high locating accuracy, due to user... 

Visual odometry(VO) is the process of estimating the egomotion of an agent(e.g., vehicle, human, and robot) using the input of a single or multiple cameras attached to it. Application domains include robotics, wearable computing, augmented reality, and automotive. The term was chosen for its similarity to wheel odometry, which incrementally estimates the motion of a vehicle by integrating the number of turns of its wheels over time. Likewise, VO operates by incrementally estimating the pose of the vehicle through examination of the changes that movements induces on the images of its onboard cameras. For the VO to work effectively, there should be sufficient illumination in the environment... 

In neural systems of living organism, moreover than differences in anatomic structure of cells, there is also differences in physiological functions of analogous cells.Specification and categorization of neurons based on physiological functions is one of objectives of neuroscience. Study of cognitive behaviors and systematic study of neural system, modeling and practical applications in neural prosthesis design are some of applications of categorizing neural cells. Neural signals can be studied by Spike rate of a single neuron activity or Local Field Potential (LFP) of a finite number of neurons. In previous studies neurons of first visual cortex are divided into two groups of simple and... 

Recent years have witnessed an increasing interest in graphene and graphene-based materials due to their extraordinary electrical properties, large specific surface area, fascinating mechanical properties, good chemical stability and remarkable electrochemical activity. The combination of these properties make graphene an attractive candidate for a wide range of applications including energy conversion and storage devices (batteries and supercapacitors), electronic devices (transistors and memory devices) and solar cells. On the other hand, graphene has a potential application in constructing different kind of sensors such as biosensors and electrochemical sensors due to its planar... 

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... 

The interesting properties of metallic nanowires provide many applications in electronic sensors. In this project, we have synthesized Pd nanowires using electrodeposition method. These nanowires are useful for hydrogen sensors by measuring field ionization current in gas. In this project, Pd nanowires were synthesized by electrochemical deposition method in PCT template with 100 nm pore size. The used solution was contained 2mM PdCl2 + 0.1M HCl. The best reduction potential was determined about -0.2V and the best time for synthesizing nanowires was 7 minutes. Chronoampermetric diagrams showed four steps, capacitive current, growth in the holes, reaching to the surface of PCT and the growth... 

Recently, the applications of two dimension materials have been increased in nanotechnology. Among this group of material the Transition metal dichalcogenide due to their energy gap and their particular optical features has attracted much attention. For instance MoS2 is a most famous material in this familyand as a semiconductor has an indirect energy gap about 1.3 eV in the bulk status and 1.9 eV in monolayer. In this project, we investigated the Nano-sheet optical properties of MoS2 by using of tunneling spectroscopy. In this procedure a thin probe is close to the surface until a quantum tunneling occurs between the probe and the sample. By measure the tunneling current we can achieve much... 

Duringfalling a viscous liquid freely on a surface, the viscous thread bends due to a phenomenon called buckling. The gravity force in this process could be replaced by an electric force in electrospinning process. In the present thesis, we have designed a number of setups in order to investigate the buckling phenomenon in two categories of helical and non-helical buckling by using direct electrospinning process. By making the collector moving, the electrospun fibers show several shapes including coiling, meander, figure of 8 shape, etc. There are three effective forces acting in this process which are viscous force, electric force and inertia. Also there are three distinct regimes defined...