Sharif Digital Repository

In this thesis, first of all we introduce the Anderson model, Multifractality, and conformal field theory. Then we try to determine some critical and scaling quantities for the critical wave functions in the 2D systems with spin-orbit interactions We implement a correction-to-scaling analysis by introducing an irrelevant exponent which leads to a proper and sharp evaluation of the critical parameters including correlation exponent, rescaled localization length and the critical disorder. Then, we survey the multifractal properties of this model and obtain some multifractal exponent in the critical point. Finally, we will survey the existence of the conformal invariance symmetry in it. Our... 

Rough surfaces and growth process are the important and significant problems of theoretical and condensed matter physics to model phenomena ranging from the extremely small (biological phenomena) to largest one (Earth’s relief). Although the equations that describe these processes are well defined, but the question of how to characterize these surfaces which display large fluctuations, is open. The existence of (often) scale invariant clusters and very large fluctuations in surface growth process are reminiscent of critical fluctuations in equilibrium systems. Therefore, it is natural to try characterizing the surface by means of critical exponents, i.e., by the scaling dimensions of various... 

Open data intermediaries, as the key species of the ecosystem, and since they are the primary consumers of open government data, are crucial to the ecosystem's growth. Without them, the data would be useless during the dissemination phase. This study aims to define the roles of open data intermediaries and explain how they are compatible with the value creation and sustainability of the open data ecosystem in order to fill a gap in the literature in this area. Two Iranian open data intermediaries, Rasmio company and Vinsabt group, which have been involved in the field of data pertaining to companies, have been studied for this purpose. The data for this study is qualitative and was gathered... 

From a long time ago cancer has been threatening human’s health, and researchers have been grappling with the phenomenon for numerous years. In the annals of this struggle, the number of cancer victims has outnumbered the survivals in a way that,until recently, suffering from cancer was perceived to be equivalent to death. Permanent defeat against cancer stems from the incomplete recognition of the phenomenon. In recent years, with the advent of technologies to extract information from the heart of cells and at the genome and transcriptome levels, man has been able to acquire a deeper understanding of cancer, its behavior and operation. Now that cancer is regarded to be a genetic disease,... 

In this research, a general model is proposed aiming at establishment of optimized application of Methane gas with maximum added value. That is, maximum added value of methane for different applications of methane including consumption as fuel, export and injection-to-wells are calculated and compared. Accordingly, results of this study are used for decision making regarding Iran’s most important gas reservoirs. In this study, maximum present net value of investment concerning comparison of petrochemical industry input and export to a number of selected countries in addition to injection in 20 years is calculated based on a specific discount rate. It is noteworthy that the scope of this... 

Lately, some investigators of polymer engineering group are working to do continuous polymer solution casting process, rather than batch process for flat sheet membrane production. For this, they use a doctor blade system but, they faced some problems during coating process. From experimental observations of the studied system, some inappropriate vorticities were seen. That’s why the system forms a non-uniform film of the solution. Air bubbling occurs at system exit which is undesirable as well. In this study simulation and optimization has been done for forming thin film in doctor blade system. COMSOL Multiphysics 4.3b was used in purpose of simulating which works on numerical finite... 

Behavioral finance researchers have introduced behavioral biases, derived from psychology, to financial models in order to make them more realistic and to increase their explanatory power.One of the best known of these biases, considered in behavioral finance literature, is overconfidence, which means investors overestimate their own knowledge and ability to evaluate securities. Several theoretical models have studied the effects of this bias on financial markets and many empirical models have examined their assumptions, looking for whether investors are overconfident or not. Explained by these models, price overreaction to private information arrival and underreaction to public signal, is... 

Cranioplasty is a surgical procedure for repairing skull defects. This surgery will protect the brain tissue, reduce pain in the lesion site and reduce the psychological burden on the patient. Cranioplasty implants should have distinct characteristics, i.e., high strength for protecting the brain, full coverage of skull defects, resistance to infection, non-expansion with heat, and reasonable price. Titanium implants, bone allografts, hydroxyapatite, and methyl methacrylate are commonly used in this surgery. However, these materials have many disadvantages that limit their use. As a result, biodegradable material and 3D printing technology are the next steps for designing scaffolds according... 

In all five continents, existence of collapsible soils such as Loess has been reported. These kinds of soils have mutual properties such as open structure, high void ratio and low dry density. Collapsible soils are always at risk of experiencing significant reduction in volume due to increasing water content or degree of saturation. Hence, this kind of soil can lead to serious problems including reduce of load bearing capacity, excessive deformation and failure of foundations.Collapsible soils exist in several regions of Iran. Consequently, researching their properties is a key point of geotechnical studies in our country. Hence, in past 10 years, several studies have been conducted by... 

In today’s world, social networks have become one of the primary sources for the creation and propagation of news. Social news aggregators are one of the main actors in this area in which users create news items and use positive or negative votes to indicate their preference
toward a news item. This approach suffers from several problems raging from being prone to the dominance of a united adversary to difficulty in decerning between correct and fake new news and lack of incentive for honest behaviors. In this paper, we propose a graphbased news aggregator in which instead of voting on new items, users submit their votes on the relations between news items. This method of voting... 

Equal Channel Angular Pressing (ECAP) is one of the most applicable severe plastic deformation procedures (SPD) which results in improvement of strength and ductility through grain refinement. WE43 magnesium alloy belongs to a group of alloys for medical industry because of its good biocompatibility. In this study, equal channel angular pressing was performed at different temperatures, strain rates and number of passes on strip-shape samples to achieve proper mechanical properties. Tensile properties, hardness and microstructural evolutions were evaluated and the results were analyzed according to the EDS test. Results shows that at 380 ℃ and 440 ℃ grain refinement was accomplished by... 

Due to special physical and mechanical properties of intermetallic compounds,somehow in between of the metallic and ceramic extremes, their applications are increased in different industries. Among these materials, titanium aluminides due to their low density, high specific strength and excellent corrosion and oxidation resistance has got more attention. Because of similar high temperature properties and lower density, these compounds are suitable alternatives for nickel base superalloys. Accumulative Roll Bonding (ARB) of pure metallic sheets and the following heat treatment in production of intermetallic compounds can be considered as a manufacturing process. The goal of this study is... 

In the first part, preparation of different kinds of polypyrrole/carbon composites and their application for drug analysis are described. In the first work, A very sensitive electrochemical sensor constructed from a glassy carbon electrode modified with a layer-by-layer MWCNT/doped overoxidized polypyrrole (oppy/MWCNT /GCE) was used for the determination of acetaminophen (AC) in the presence of codeine and ascorbic acid (AA). In comparison to the bare glassy carbon electrode, a considerable shift in the peak potential together with an increase in the peak current was observed for AC on the surface of oppy/MWCNT/GCE, which can be related to the enlarged microscopic surface area of the... 

In this investigation, silica-based iron-metal catalyst was synthesized by the Atomic layer deposited (ALD) method with iron-acetylate (Fe(acac)3) as a precursor in different loading dosages. The synthesized catalyst were characterized by nitrogen absorption and excretion (BET), by Field Emission Scanning Electron Microscope (FESEM), X-ray diffraction (XRD), and Temperature-Programmed Reduction (TPR), Fourier-transform infrared spectroscopy (FTIR), Atomic Emission Spectroscopy (ICP) etc.
The temperature range of 180 to 200 °C was determined for the self-limited chemisorption of Fe(acac)3 on the silica surface as the first and the most important step in a single atomic cycle. Also the... 

Austenitic stainless steels have extensive and special mechanical properties because of austenite to α΄-martensite transformation due to plastic work. Obtaining a process path that provides maximum strength and flexibility and minimum α΄-martensite content (α΄-martensite increases corrosion current) in these steels is important in the industry. Applying the aging process after applying plastic strain (single-stage aging) results in an increase in strength of up to 200 MPa and an increase in hardness of up to 60 Vickers. However, single-stage aging does not cause significant changes in the amount of α΄-martensite in steel and in the temperature range of 400 to 500 ° C, it causes a slight... 

In this research, it has been trying to implement Virtual Structure method for formation flight of multiple spacecraft. In this method, a virtual solid frame with virtual center of mass is considered and agents are arranged in a formation with respect to the virtual center. In this work, a formation keeping control system is implemented in which a feedback from formation to virtual structure and vice versa is considered. The method is implemented firstly in a nongradient field and then developed into a circular orbit in order to investigate the in-orbital effects. An algorithm for collision avoidance, based on relative distances and relative velocities, was also developed. The algorithm was...