Sharif Digital Repository

In this study, with respect to previous projects, we focused on size reduction of hollow and endohedral fullerenes research reactors. For this reason, we set up two reactors having 1/2 and 3 liters volumes and then such parameters as pressure, reactor temperature, arc duration time, arc time interval and the working electrical current through the electrodes circuit, in both reactors were optimized. The reactors, 3- and 1/2-liter reactors were of types of horizontal and vertical, respectively. In this project spatial angle between two electrodes were also found as effective variable on fullerenes yield in the 3-liters arc reactor for the first time. We found that upon correction of the... 

The water and energy demand increase as the population grows. Increased usage of energy leads to scarcity of available resources and limited absorption capacity of environment. Development of efficient and environmentally compatible energy conversion technologies are conceived as an important option for resolving pressing challenges. Compatibility with environment requires considerable reduction in the share of fossil fuels and efficient utilization of renewable energy sources. Hence, development of high-efficiency solar energy systems is becoming an important challenge in the energy sector. The present study is involved with development an integrated solar system based on the application of... 

The goal of the present study is to analyze the effect of CaF2 and nano-TiO2 as additives on formulation and properties of common dental glass-ceramics. To achieve the goal, a glass system based on SiO2-Al2O3-Li2O-K2O-P2O5-ZnO-ZrO2 was considered to produce glass-ceramic samples and the additives, nano-TiO2 and CaF2, with the 0.5, 1, and 1.5 %Wt was added to the system. After the melting process, the glass samples poured in the water and ferrite was produced. In the next step, the ferrite was milled and pressed. In the heat treatment step, the samples were treated in the temperature range of 650-850°C in order to gain lithium disilicate glass-ceramics. In the last step, the chemical... 

The increase in the amount of groundwater exploitation and climate changes has made land subsidence into one of the environmental problems and has caused many problems in various infrastructures such as urban areas, residential buildings, and vital arteries such as power transmission lines. Many areas of the country, especially areas with smooth topography such as plains where alluvium accumulates, due to excessive exploitation of groundwater resources and climate changes, are facing a decrease in the level of groundwater, an increase in the thickness of the unsaturated layer, and as a result, progressive subsidence. In particular, the destructive effects of land subsidence on power... 

Zinc-bromine redox flow batteries are promising for large-scale energy storage applications due to their high energy density and open-circuit voltage. Proposed models for predicting these batteries' performance are limited due to challenges such as zinc deposition during the charging step and the utilization of a complexing agent. In this study, a 2D dynamic model was developed to investigate the battery performance. The kinetic equations for half-reactions are considered according to their two-step electron transfer mechanism. The model predictions were validated against experimental data reported in the literature for different current densities. Afterward, effects of various operating... 

The goal of this thesis is to represent some application of algebraic topology specially homology and simplicial structures in data analysis and image processing. First the notion of topological persistence will be introduced and next for computing that several efficient algorithms will be proposed. Also complexity of the algorithms base on the topological spaces and by some algebraic topology tools. And it will be tried to test this theorical algorithms on real data and represent some application of topology in real data analysis. To do that, at the begining the tools of algebraic topology will be reviewed and the notions like singular complexes and singular homology and some related... 

In the first part of this work, citric acid monomer was selected to produce dendrimer through the divergent method using logical conditions (for controlling its functional groups) on the base of poly (ethylene glycol) as the core. Triblock copolymers (ABA-type) of citric acid and poly (ethylene glycol) (PCA-PEG-PCA) as biocompatible compounds were synthesized in four different molecular weights and applied as nanocarriers. The structure definition of the molecules and nanoparticles were carried out using different spectroscopy methods. Diameter of the synthesized copolymers was investigated using dynamic light scattering (DLS) experiments and transmission electron microscopy (TEM) and it was... 

This research focuses on the development and implementation of a wireless power transfer system based on magnetic induction to power wireless neural recording devices in experiments where animals move freely in a cage. The main goal of this research is to reduce the weight of the recording devices by eliminating the battery and using wireless power transfer. By removing the battery and employing magnetic induction, the final weight of the device is minimized, eliminating the need for battery replacement or recharging, and reducing the negative impact of the device's weight on the natural activities of the test animals. Power transfer for wireless neural recording devices is achieved through... 

Since the classical continuum theory fails to deal with the problems associated with defects, stress concentrators, and relevant deformation phenomena in solids, alternative approaches that can detect the atomistic nature of materials' fracture are required. The deficiency of the capture the size effect which yields delusively high values for some components of the stress field right on the edge of the stress concentrators, and its weakness in describing the complex interaction between small inhomogeneities, cracks and the like when they are only a few nanometers apart, are among some of the disadvantages of the classical approach. In recent years, however, atomistic methods are emerging to...