Sharif Digital Repository

One of the most simple questions of particle physics, which is still unanswered, is whether neutrino and antineutrino are the same particles or not. The answer to this question has many implications for the physics beyond the Standard Model, supersymmetric theories and unified theories.
In this thesis we first introduce Majorana fermion, the best candidate for which is neutrino. Then its implications for going beyond the standard Model have been discussed. At present time, the most important experiment which can prove this guess is neutrinoless double beta decay which has been studied in details in this thesis. The study of the theoretical and experimental aspects of neutrinoless double... 

In this study formation of a single bubble on fluidized bed distributor is investigated. Digital image processing and pressure sensors are used to analyze bubble characteristics. Effects of density and the size of particles on bubble diameter, formation time, separation and passing velocity was studied in different flow rates of nozzle. Bubble diameter when is separated from nozzle was greater for lower density particles which have the same size. The ratio of diameter formation was approximately equal to inverse of densities ratio. Bubble formation time is decreased by increasing the flow rate of nozzle and the formation time is approached to a specified value. In addition, it was observed... 

The Reliability of substation structures with consideration of earthquake uncertainties is one of the most important subjects in structural analysis in recent years. In this project we first introduce IEEE-693-2005, which is the most effective and comprehensive seismic design code for electronic substations. Also in second chapter the rudimentary aspects of Reliability Theory and methods for evaluating the reliability of substation structures is introduced. Then with modeling the most common and most important electronic substation devices in Iran, with consideration of all seismic parameters and their uncertainties, the reliability of these structures evaluated. In this project for... 

This research deals with the problem of scheduling independent preemptive jobs on identical parallel machines, to minimize the total completion time (makespan). The transportation of an interrupted job from a machine to another machine requires considering a constant transportation delay i.e., Pm|prmp(delay)| Cmax. This delay is called transportation delay. We propose a Mixed Integer Linear Programming formulation for the research problem in case of two machines i.e., P2|prmp(delay)| Cmax. Since the research problem is shown to be NP-hard, a particle swarm optimization (PSO) algorithm is applied to solve the problem approximately. Based on the frequency of using local search procedure, three... 

Recently various speaker adaptation methods in HMM-based speech synthesis are proposed. The importance of adaptation techniques is that we can design a system in which speech is generated with high quality and target speaker characteristics through limited adaptation data sets.
In this research, we focus on adaptation based on clustering and develop a new and novel method using eigenvoices in order to adapt a new speaker. We employ this approach for the first time in HSMM-based speech synthesis systems and its goal is to reduce the parameters and adaptation data of the system. In our proposed method, first some speaker dependent models are trained. For each model we combine the... 

Today, computer simulations are employed prevalently by researchers to understand biological processes. The tendency to use computational methods has been increased recently due to the high costs and errors of experimental methods. Integrins are membrane proteins that mechanically attach cells to the extra cellular matrix (ECM) and derive some behaviors such as cell migration. Moreover, integrins have biochemical functions. They transduce environment signals and trigger chemical pathways. As a result, integrins regulate cell shape, motility, etc. The investigation of integrin behavior in a real environment is very difficult due to the presence of many other proteins that interfere with the... 

The purpose of this study is to investigate the effect of Google search volume of trading tickers listed on the Tehran Stock Exchange, on volatility, abnormal returns, and trading volume. For this purpose, data related to the search volume as well as trading data for 22 trading tickers in the list of the 50 largest stock market companies from 2016 to 2020, has been extracted. After collecting data, the required calculations to estimate volatility and abnormal returns, as well as standardizing search volume and trading volume, are performed. Then the desired variables for all 22 selected tickers are placed in a data panel. Then, using the two main research models, descriptive and predictive... 

Asset pricing models are one of the most important tools in investment management and portfolio allocation. Multi-factor asset pricing models try to explain the relationship between risk and expected return through a limited number of macroeconomic, fundamental or statistical factors. Usually, these models are suggested based on the US market and its intrinsic qualities. Although, there are some similarities between the Iranian and the US market, these economies are structurally different and therefore, proposing a proper multi-factor model based on the Iranian market’s fundamental characteristics will greatly improve the understanding of risk-return relationship in this market. In this... 

In this research, we propose a dynamic econometric microstructure model of trading, and we investigate how the dynamics of trades and trade composition interact with the evolution of market liquidity. We estimate a bivariate generalized autoregressive intensity process for the arrival rates of informed and uninformed trades for fifty actively traded stocks in Tehran Stock Exchange over one year of transaction data. Our results show that both informed and uninformed trades are highly persistent, but that the uninformed arrival forecasts respond negatively to past forecasts of the informed intensity. Our estimation generates daily conditional arrival rates of informed and uninformed trades,...