Sharif Digital Repository

US 2008 financial crisis, spread across the international stock markets in the second half of the year 2008. The crisis decreased the returns and increased the volatilities of almost all of the stock indices, however, its effects on Iran’s stock markets were unexplored. Financial limitations create an exclusive situation in Iran’s stock market. Using weekly data on the stock indices from July 2006 through August 2009, this study aims to exam in the contagion effects of the global financial crisis through the main indices such as S&P500 and FTSE100 on Tehran Stock Exchange indices: industrial and financial intermediary indices and The First and the Second indices of Tehran’s Stock Exchange.... 

Recent advances in storage and processing have provided the ability of automatic gathering of information which in turn leads to fast and contineous flow of data. The data which are produced and stored in this way are named data streams. It has many applications such as processing financial transactions, the recorded data of various sensors or the collected data by web sevices. Data streams are produced with high speed, large size and much dynamism and have some unique properties which make them applicable in precise modeling of many real data mining applications. The main challenge of data streams is the occurrence of concept drift which can be in four types: sudden, gradual, incremental or... 

This research aims to introduce a new integrated fault tolerant attitude control system of satellites based on the neural networks. First, a linear controller and an optimal controller are designed assuming that no fault occurs in the reaction wheels of the satellite. It is obvious that these controllers are not able to respond properly when a fault occurs. Therefore, artificial neural networks are employed in the fault tolerant controller design. Neural networks are well-known for their adaptiveness and the ability to learn the dynamics of a system. Therefore, they can be used to predict the faulty conditions. In this research two approaches are examined to deal with the faulty conditions.... 

People use social networks to share millions of stories every day, but these stories rarely become viral. Can we estimate the probability that a story becomes a u/rof cascade? If so, can we find a set of users that are more likely to trigger viral cascades? There are many factors influenced the message virality. In this thesis, we investigate the effect of graph structure, diffusion pattern as well as the message text on virality measure. Finally, the authors solve both source localization and inferring COVID-19 network via propsed methods.First, the authors investigate probability estimation and maximization of cascade virality. In this section, we develop an efficient viral cascade... 

The harmful environmental effects of gases resulting from the combustion of sulfur compounds in fuel, poisoning of catalysts, corrosion of equipment, as well as the intensification of environmental considerations and new standards adopted for the maximum amount of sulfur, have made the desulfurization of fuels important; Meanwhile, the desulfurization method using hydrogen has a high potential to remove sulfur compounds. For example, diesel fuel contains a variety of impurities such as sulfur, nitrogen (basic and Non-basic), and aromatic compounds, the sulfur in diesel fuel causes many problems related to environmental pollution and corrosion of engine components. Also, due to the high... 

First, we review in an appropriate way the researches regarding building blocks of a wireless network (Shannon channel, multiple access channel, broadcast channel, interference channel, relay channel) and then: • We consider two cases for a relay and describe the essential role of the relay with three Markovity conditions; define Almost General Relay Channel with Decode-And-Forward (AGRCDAF) strategy and determine its capacity. Then, we prove that our capacity theorem not only includes all known capacity theorems as its special cases but also potentially is applicable to other relay channels and is validated by its consistency with previous results related to special cases of broadcast and... 

Due to the development of heat pipes in different industries and special characteristics of heat pipes, in this study, it has been tried using computational fluid dynamics (CFD) method to simulate a heat pipe heat exchanger that can be a replacement for the normal radiator. The experimental model of this heat exchanger has been tested at past studies and the numerical simulation of the heat exchanger will analyze at present study. The use of heat pipe in the car radiator has many advantages such as reducing fluid pressure drop through the heat exchanger, high reliability due to the particular structure of the heat exchanger (individual performance of each heat pipe) and improving heat... 

In this project the main aim is to model the interaction between the cytoskeleton and cell membrane. In order to model the membrane and cytoskeleton it is used a discrete model, which contains several beads. For modeling the interaction between the beads it is used different kinds of energies. It is used four potentials in a 2D model for modeling the interaction between the membrane beads and it is used SSLJ potential in order to model the interaction between the cytoskeleton and cell membrane. Furthermore, this potential is used to model the interaction between the cytoskeleton filaments. Due to this potential, the cytoskeleton filaments can cross each other in the 2D model. For modeling... 

Land subsidence is a gradual settling or sudden sinking of the land surface from changes that take place underground. There are different causes of land subsidence; most notably, groundwater overdraft and severe weather conditions. Subsidence of the land surface due to ground water overdraft is caused by an increase in the intergranular pressure in unconsolidated aquifers, which results in a loss of buoyancy of solid particles in the zone dewatered by the falling water table and accordingly compaction of the aquifer. In this study, an experimental approach was developed to examine applicability of Microbially induced carbonate precipitation (MICP) for land subsidence control under...