Sharif Digital Repository

With new progresses in technology, a growing need to power energy has emerged. In Iran most of power plants are far from cities and therefore expansion of power network will cause long transmission lines with high capacities which connect power plants to cities. There are three solutions for these kinds of lines: 1) two-circuit transmission lines 2) higher voltages 3) new forms of transmission lines (HVDC and compact). In this thesis some of these suggestions have been analyzed to find the best solution for a 560 Km transmission line in Iran.
Designing transmission lines has a lot of steps which all are related to each other. In this project a comprehensive algorithm has been utilized to... 

In this thesis, the separation process for used and relatively new catalysts of residue fluid catalytic cracking unit by applying an electric field was evaluated. The main purpose of this dissertation is to simulate and design a separation system for separating used and relatively new catalysts of the FCC process in the electrostatic fields. In this regard, various separators were studied, and most of them were simulated under different circumstances. Finally, after examining and analyzing the particle behavior in each of the scenarios, the proposed system was introduced as more effective and efficient than the other separators in order to achieve the ideal separation of the used and... 

In recent decades, metal nanoparticles have been used in medicine for example in cancer treatment. There have always been debates on the nanoparticles specifications such as particle size, amount of surface charge and the particle material. Meanwhile, the study on selecting appropriate properties of nanoparticles for this purpose is very essential and expensive in medical science. In order to access the best efficiency and the least mortality of the patients in treatments, simulation studies can support the medical scientists. In this thesis, the goal is to study transferring nanoparticles as a drug or included drugs through created hypothetical micro-channels in cancerous cells membrane.... 

The electric field induced response of a charged droplet in an uncharged gel is calculated theoretically. For modeling, the gel is considered as a soft porous solid that is saturated with a Newtonian electrolyte and modeled as a continuum that contains 3 phases: a porous, soft and compressible solid, an incompressible Newtonian fluid and the ions inside fluid. Droplet is modeled as a charged incompressible Newtonian fluid immiscible with the gel. The droplet-gel interface is considered as a surface with electrostatic potential ζ . After obtaining governing equations, they solved by using perturbation methodology and linear superposition. Boundary conditions, especially at the droplet-gel... 

The nuclear pore complex mediates all transport between the cell cytoplasm and the nucleus. Being inspired by this biological system, in this project we intended to design an artificial gate by using polyelectrolyte brushes in a cylindrical nanochannel, which will be opened by applying a tangent electrical field and will close by eliminating the field. Grafted polyelecrolyte brushes have the potential to be useful for the design of advanced gating systems for many applications like functional and conrolleble MEMS devices. In order to design the desired gating system we have employed the ESPResSo software to conduct a coarse-grained molecular dynamics simulation in NVT ensemble to simulate... 

By direct and alternating electric field applied to thin film of liquid suspended in the air we can spin out and control it. Rotation pattern depends on the geometry of the electrodes and the applied magnetic field. This is called a rotating liquid film (Liquid Film Motor). To determine the cause of rotation, different models have been proposed. In this project we have tried to check the accuracy of any of the models. Using particle velocimetry using the photo, we calculate the velocity pattern. Then, using the Navier-Stokes equation calculate the acceleration and viscosity from the velocity. Then, for a special arrangement using a finite diffrent method, electric potential and the electric... 

Membrane filtration systems are one of the most widely used and effective methods for desalination of saline water in the seas and oceans and treatment of industrial and domestic effluents in order to provide the fresh water resources needed for human survival on the earth and also meet the needs of various industries. The low efficacy of the traditional technologies necessitates the introduction of novel desalination methods. For this purpose, carbon-based membranes have been proposed as high-performance membranes because of their high mechanical strength, ultrafast permeation, and controllable pore size. In this study, by conducting molecular dynamics simulations, the effects of electric... 

Over the past few decades, brachytherapy has been used as one of the leading methods in the treatment of a wide range of cancers, including breast cancer. Due to the high dose gradient of brachytherapy radiation sources, this method is used to treat such tumors that are grown at the vicinity of sensitive points or tissues of the body. Therefore, as irradiation get started by implanting radiation sources in the desired position, at the same time healthy tissue are also receiving the same dose as tumor tissues do Reducing healthy tissue dose along with increasing the dose of tumor tissue is one of the challenging topics that researchers are always looking for a solution. In the left breast... 

Electric field sensors are one of the common types of sensors that are widely used today to record changes in the electric field in underwater environments, also record pH changes in different materials. This type of sensor is inspired by the shark mucous membrane. In this study, silver / silver chloride silver (Ag / AgCl) was used for three methods of silver filtration directly in electrolyte containing chloride ion, Electrophoretic electrode method and electrode making method using silver oxide adhesive. Part of the electrodes manufacturing method involves converting part of silver into silver chloride. The made electrode has a length of 7 cm and a diameter of 0.5 mm, with its core made of... 

Drop formation is an interesting field of research due to its wide-range of applications, such as drug delivery, biomedical studies, pharmaceutical industry, Lab-On-Chip (LOC) devices, etc. In recent years, researchers have used numerical studies to better understand how the process of forming and carefully examining the factors that affect quality improvement. One of the most effective methods in controlling the size and the process of drop formation is use of external force in microfluidic devices. Among the external force in this study, an electric field with oscillating current was used. Rapid methods for creating, deforming, and breaking up of drops in microfluidic applications are... 

Investigation of electrohydrodynamic behavior of fluids under electric fields is a challenging and impressive matter in condensed matter physics. In this thesis, inspired from previous works on liquid film motor, a new phenomenon has been observed and its properties has been investigated.Here by making a new device named “Liquid Film Electric Generator” we produced potential difference on the rotating suspended liquid film under electric field. The power conducted by electrodes has been generated on the surfaces of the film. By this method, under electric field of 1000 V/cm, micro-watt electric power can be achieved on a liquid film of diameter of about 1 cm.We explained this phenomenon on... 

Wide utilization of nanomanipulation as a promising approach in microorganisms, nanoelectromechanical systems (NEMS) and assembly of nanostructures remarks the importance of nanostructures’ motion in electric fields. Despite of many reports on manipulation and assembly of nanowires (NWs) in non-uniform and alternating electric fields by dielectrophoresis, and also rotation of NWs in rotating electric fields, there is still a lack of knowledge on rotational and translational dynamics of metallic and dielectric NWs in uniform static electric fields. In this dissertation, we study the dynamics of silver (Ag) and titanium dioxide (TiO2) NWs, with diameters and lengths in the range of 40 to 100... 

Cancer is the second leading cause of death in the world, with a high annual cost of treatment. As the cancer progresses, the cancer cells in the bloodstream metastasize to other parts of the body, causing the disease to spread throughout the patient's body and disrupt organ functions. sepration of cancer cells in the bloodstream inhibits the growth of cancer. Cancer cells differ from healthy cells in some features, such as size, electrical charge and polarization. These features can be used to seprate cancer cells from healthy cells.In this study, cell surface electrical charge was used as a biomarker to seprate cancer cells. By passing blood flow through a chanal and applying an electrical... 

Studying the behavior of electromechanical systems containing nanostructures, because of their widespread applications in the nanoscience and technology is of great interest. For this purpose, this work is devoted to analytical and exact determination of the electroelastic fields associated with periodic and arbitrary distributions of electromechanical nano inclusions and nano inhomogeneities of various shapes within electroelastic mediums of general anisotropy. Since classical continuum Theories are inadequate in accounting for size affects in nanostructures, a first strain gradient - first electric field gradient theory is applied. The present work considers Piezoelectric and Flexoelectric... 

Due to the large application of electro-sprays in various industries, the study of the stability of electro-hydrodynamic flows is important. This thesis examines the stability of cylindrical liquid jets in the presence of an axial electric field. The definition of this jet is a simplified model of electrospray, electrospinning. In this model, the stability of a free incompressible cylindrical flow with surface tensile strength, conductivity, polarization, viscosity, and dielectric constant is determined, irrespective of the solubility of the jet and the surrounding fluid (air), in the presence of uniform axial electric field has taken. This will be done by adding the forces generated by the... 

The aim of this study is to find a formulation to investigate the catalytic effect of the electric field on the kinetic pathway of a chemical reaction. The catalytic effects of the electric field can be explained by the effect of the external electric field on the stability of the transition state relative to the reactants.The effect of the external electric field on the reaction rate for redox reactions have been proven, but this effect seemed unlikely for non redox reactions. Recently, the role of the electric field in the rate of such chemical reactions, as well as its catalytic activity,has been demonstrated experimentally and computationally. In previous studies, reactive components... 

Transferred Electron Device is a semiconductor device being capable of generating oscillation in microwave frequencies. Applying a bias voltage to the device and putting it in a resonant circuit, a periodic waveform in the output current is observed. The cause of the generation of oscillation in the device is related to the characteristics of velocity-field in the device. In some part of the characteristics, it is observed that increasing the field inside the device causes the velocity of electrons to be reduced. This causes the generation of the negative conductance and the oscillation of the output current under some conditions. The purpose of this thesis is to represent an equivalent... 

Unique properties of Gold at nanoscale have made it one of the most popular substances used in nanotechnology. The interaction of Gold and Thiolates is one of the most favorite fields of research. Extensive studies about this interaction have revealed the importance and usage of this system in future technology. Due to difficulties of experimentationat nanoscale, computer simulations arevery important. Although interatomic potentials lead to higher computational speeds, they have deficiencies in precise simulation of some phenomena. Ab-initio methods, such as density functional theory, provide powerful tools to increase the accuracy. In this research, the interaction of gold and thiolates... 

The use of superhydrophobic surfaces is one the most promising methods for reducing the friction and increasing the flow rate in fluid transfer systems. Since in such systems the surface structure plays a key role, in the first part of this study, the performance of the hierarchical nanostructures is explored. These nanostructures are inspired by the superhydrophobic surface of the lotus leaf. The flow is considered between two walls with hierarchical nanostructures and simulate the system via the molecular dynamics (MD) method. The size of the nanostructures and the distance between them have been studied to find whether a design with maximum flow rate exists. The nanostructures have two... 

Nickel aluminides are intermetalics with complex structures that have high metlting points. However, brittlement at room temperature and low high_temperature strength (above 700 ̊C) can be mentioned as their short comings. Nowadays, many efforts have been proceeded to produce theirs composites, so that one can benefit from ceramics and intermettalics properties simultaneously. In this project, the main was aim to produce NiAl matrix nanocomposite reinforced with Alumina Al2O3. The composite is processed using milling and mechanical alloying. This is a good way to produce intermetallics and their composites with high melting points without any need to supply high temperature during...