Sharif Digital Repository

There is an increasing need for food by the growth of population. To meet this need, the use of pesticides is increasing. Among pesticides organophosphorous compounds are the ones with the most usage. Liquid and gas chromatography are commonly used to measure orghanpphosphrous pesticides. These methods are relatively time consuming and require a tedious sample preparation.
Herein we report a sensitive colorimetric method for detection and measurement of Azinphos methyl, based on unmodified gold nanoparticles aggregation and changes in plasmonic band. Azinphos methyl, containing different soft acidic groups acts as a bridge, causes aggregation, and changes in plasmonic band. Changes in... 

The world around us changes almost every second, so the economy in this world feels it more by every single minute. When we look at the organizational structures, they experience lots of things for keeping the companies competitive and the human resources have the main role among the other stimulating factors.The human resource management and its improvements have done a lot in this century to organize and manage the human problems in organizations. After that those companies that had more effective strategies become on top of this important management system. By changing fast the work models companies experience more and immediate changes that may not happen even through the years. In this... 

Many problems in the field of 0-1 integer programming are NP-Complete. Execution time for exact solving these problems is very high due to many constraints and decision variables. Hence, scientists use Fast algorithms, for example, the Greedy algorithms, in the approximated solution of these problems.A classic greedy approach may not search the whole solution space for better choices. However, other methods with a greedy approach, such as meta heuristic and hyper heuristic, in addition to local search, consider the more search space. These methods search randomly, so it does not provide a good guarantee for finding the proper solutions. Finding suitable solutions in this category of... 

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... 

Nanotechnology inrecent yearshas attractedthe attention of manyscientists and industrialists. Having atiny structure with extraordinary properties of nanoparticlesin the fields of electrical, mechanical and thermal, leading to their use isgrowing and newer application sarebeing found forth eseparticles. One of them Nanodiamond powderiswidely usedin the industryhas found wideapplication. Among these can be used in electrochemistry, chemical coatings, pastesand suspensions, add thepolymer, ceramic and industrial rubber and adhesives,adsorbentsand catalysts, filters and membranes, and finally cancer treat mentnoted. One of these applicationsisinPolymers and Rubber Industry. According to earlier... 

In this study solid lubricants MoS2 nanoparticles with average size 50 nm and hard ZrO2 nanoparticles with average size 51 nm were used in watts bath and Ni/ZrO2-MoS2 composite coatings were prepared by pulse plating technique. Effect of current density, frequency, duty cycle, surfactant type and concentration of particles in the electrolyte on the amount of particles in the coatings were investigated and optimum conditions were determined to create composite coatings. Scanning Electron Microscopy (SEM) and x-ray diffraction (XRD) analysis were performed to study the morphology, structure, chemical composition of coatings. Corrosion testing of coatings by potentiodynamic polarization in... 

It is assumed in many traffic assignment models that people choose their path based on shortest travel time. Few empirical studies of revealed route characteristics have been reported in the literature. In this study, first, an innovative internet-based survey using Google map has been designed and implemented. The sample includes the people who commute to Sharif University of Technology in the morning peak hours. Next, observed routes in 134 valid questionnaires have been analyzed by using Tehran network database and VBA programming. Besides the length and travel time of each path, other characteristics of the observed route such as the number of right, left, and U-turns, number of... 

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,... 

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... 

This research investigates the impact of public attention, measured using Google Trends data, on stock transactions in the Tehran Stock Exchange, with a distinction between retail and institutional investors. The primary objective of the study was to assess the relationship between public attention and the number, volume, and value of buy and sell transactions for these two groups of investors. Weekly data on Google search trends and trading variables for 486 stock symbols were analyzed. The findings revealed that public attention, particularly among retail investors, has a significant impact on stock transactions. This effect peaks with a one-week lag, supporting the hypothesis, consistent... 

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...