Sharif Digital Repository

Bonding gravity with Quantum mechanics has always been a challenging issue. So that, accomplishing a theory of quantum gravity is one of the most important research topics in High-Energy Physics.Information paradox in black holes is among such issues which connect quantum mechanics with gravity. Black holes as a natural solution of Einstein equations have a distinction, with other solutions, since there exists an event horizon that imparts space-time into two causally disconnected regions.According to Hawking’s calculations, black holes would evaporate over time by the thermal radiation. This resulting thermal radiation has less information than the initial collapsed matter in a pure state.... 

The information paradox is one of the most important questions around black hole physics. The problem is raised since the operators which are responsible for the evolutions in quantum mechanics are unitary while the black hole evaporation seems to be a nonunitary evolution (Since a black hole which has been formed from the collapse of matter in a pure state evaporates to a mixed thermal state eventually). This loss of information during the evaporation process is known as the information paradox.Recently many attempts have been made to investigate this problem holographically, actually to see if the information is really lost and if not how one can recover the information.Our main goal is to... 

Not all effective theories in the low energy limit are compatible with quantum gravity. The goal of the swampland program is bringing the necessary criteria to test these effective theories and examine their compatibility with quantum gravity. This set of conjectures determines which theory is effective in the perspective of the self-consistent theory of quantum gravity which is actually string theory. A very important connection (through the swamp program) between high energy physics (UV) And the physics of the low energy limit (IR) can provide very important explanations for our questions. Among them are the cosmological constant problem in general relativity and the hierarchy problem in... 

Not all low-energy effective theories are compatible with quantum gravity. The purpose of swampland program is to provide the necessary characteristics to test these theories and measure their compatibility with quantum gravity. Accordingly, this group of conjectures determine which effective theory is in the landscape of self-consistent quantum gravity which is String Theory. An important connection is provided through the swampland program between the high-energy limit physics (UV) and the low-energy limit physics (IR) that can provide immensely important fundamental explanations for our profound and consistent questions such as the hierarchy problem in elementary particle physics and... 

In recent years, a series of deep connections have been found between the ideas that used to be in the Algebraic Theory of Quantum Fields and the important problems of High Energy and Fundamental Physics. In the 1960s and later, some people who were mostly closer to mathematicians were trying to formulate the basics and principles of Quantum Field Theory in mathematically precise way. Many and various efforts have been made in this direction. One of these important efforts has been the Algebraic Theory of Quantum Fields. The main motivation in the Algebraic Theory of Quantum Fields is to focus on the operators and observables of the theory and study the algebraic structure between them instead... 

According to general theory of relativity, collapse of matter under gravitational force leads to the formation of black holes. Considering the quantum effect shows that black holes have thermal radiation which cause them to evaporate. After a complete evaporation, the state of radiation can not contain all information of initial matter. In other word, this process does not obey unitary evolution of quantum mechanics. This is called the black hole information paradox, which has been one of the most challenging problem of theoretical physics for several recent decades. Recently, a deep connections between asymptotic symmetries, soft graviton theorem and gravitational memory effect has been... 

Entanglement is an immediate consequence of quantum mechanical pos- tulates and is thus an indispensable part of studying quantum systems. A very useful quantity which can appropriately quantify entanglement between the degrees of freedom of a composite quantum system is En- tanglement Entropy (EE).
Over the last few years, this subject has attracted a lot of interest both in QFT and in the context of holography. On the one hand, an intu- itive geometrical Holographic model for entanglement entropy has been proposed in the context of gauge/gravity duality, and on the other, var- ious issues concerning entanglement have been explored, e.g. in quan- tum computation, quantum information... 

Nowadays, the reduction of crude oil quality and the growth of environmental restrictions are the main challenges in oil refineries worldwide. The high demand of lighter refinery products and the shrinking market of the heavy products, highlighted the role of heavy residues conversion technologies.Gasification technology consumes these heavy refinery residues and produces clean syngas. By this way and the integration of gasification with power generation cycles, more value added products such as electrical energy, steam and hydrogen can be provided. For this aim to be achieved, three different scenarios are developed and investigated in this project. The first scenario includes the... 

Air pollution is treating civilians of megacities. One of the most dangerous pollutants is particulate matters with the aerodynamic diameter less than 2.5 microns. For reducing the concentration of these particles in Tehran’s atmosphere, it is necessary to investigate the source’s contribution and emission factors. Receptor models such as Chemical Mass Balance are used for source apportionment analysis. The major input of these models is the source profile. Since vehicles are the only source of pollutant in the urban tunnels, these tunnels are ideal media in order to investigate the vehicle’s source profile and emission factor. This project aims to determine the source profile and the... 

The operating conditions of the battery in renewable energy systems affect its electrochemical behavior and degradation process. Recent research mainly estimates battery lifetime through conventional methods such as counting the number of equivalent battery life cycles or based on simple experimental models that may lead to optimistic predictions in battery service period. In this study, a reduced-order thermoelectrochemical-aging battery model is developed for the application of renewable energy systems and the battery degradation analysis is investigated by this model. The proposed microscopic model evaluates the effect of battery operating conditions such as state of charge, current and... 

The aim of this paper is to perform macro stress test for one of Iran’s private banks using bank’s quarterly data from Q-4 1383 to Q-4 1389. To do this, the relation of bank’s default rate with macroeconomic indicators like house prices and the growth rate of value added of services; as macroeconomic risk factors; was investigated by a linear model. Results show that the bank’s default rate has a negative relation with both risk factors.Stress testing, using monte carlo simulation; shows that reverse shocks to both house prices and the growth rate of value added of services leads to severe increase in bank’s default rate; so that with decrease of both house prices to 4 million rials at... 

In this thesis, the improving effects of TiO2 nanotubes (TiO2NTs) fabricated by anodizing of titanium as suitable substrate for deposition active materiales in supercapacitors were considered. PANI/Pd/TiO2NTs electrodes with highly porous structures and good capacitive characteristics were prepared by electrodeposition of polyaniline on palladium nanoparticles loaded TiO2 nanotubes. The results illustrated that the specific capacitance of these electrodes was around 1060 Fg−1 in 1.0 M H2SO4 electrolyte as measured at a constant current of 2.0 Ag−1, whereas it was 210 Fg−1 for the PANI/TiO2NTs electrode. NiO-ZnO/TiO2NTs electrodes were synthesized by the electrodeposition of... 

Linear structure of polypropylene, which is a direct result of Ziegler-Natta catalysts, led to the melt strength of the polymer is low and it does not show hardness strain. This defect is cause to the use of polypropylene in some processes, such as thermoforming, making foam etc. are limited. A main methods to solve this defect are branching structure of the polymer. There are three general methods for this purpose, which are modified by chemical, electron beam irradiation and polymerization in the presence of metallocene catalyst. The first two methods that past processing, polypropylene branching using linear type is produced, while the third method branching occurs during polymerization....