Sharif Digital Repository

In the proccess of making key slots in lock parts, broaching is necessary. The only procedure or at least the best procedure for making the slots is broaching. High speed and precision, surface quality and the ability to create complicated surfaces in one step are the advantages that make broaching suitable for this product. The cost of tool maintainance and replacement is very important to make this process efficient economically, therefore, determining the factors affecting tool life are important for industries. The purpose of this study is to increase the life of narrow broaching tools. In other words, in this study, the purpose is to design and manufacture the tool in such a way that... 

Image segmentation has a huge amount of applications in machine vision, target detection, medical image processing, etc. In many medical researches such as Organ and Gland Volume Specification, Analysis of Anatomical Structures and Multimodal Image Registration, Organ
Segmentation is the first step of preprocessing.Since detection of diseases out of medical images depends on organ segmentation results,the segmentation process is done by experts which has a lot of disadvantages such as high time computation, high cost, etc. Hence, designing algorithms that can segment images with high accuracy and need minimum user interaction are desirable. So, in this thesis, a new
knowledge based... 

In this project a new molybdenum (VI) complex with tetradentate Schiff base ligand which was soluble in water was synthesized and characterized. In the first step of ligand synthesis, the reaction was performed between salicylaldehyde and aniline, and then used concentrated sulfuric acid for sulfonation. In the next step 5- sulfosalicylaldehyde sodium salt was formed by removing of aniline with heating and using sodium carbonate. In the presence of ethylendiamine and bis (acetylacetonato) dioxomolybdenum(VI) the final product, cis-dioxo sodium (N,N-bis (5-sulfonatosalicyldene)1,2-diaminoethane) molybdenum (VI) complex was synthesized. The complex was characterized by (CHN) elemental... 

In this dissertation, the application of frequency and space diversities in radar target parameter estimation are investigated. On this basis, multi-frequency signal is used to improve the range resolution, array structure is used to increase the angle estimation accuracy and the merger of the multi-frequency signal and array structure are used to increase the maximum number of targets that can be uniquely identified.Considering the desirable properties of multi-frequency signals such as high bandwidth efficiency, high range resolution achievement without chip length decrease and …, there has been increased interest in the vast area of research on the design of such signals that has... 

Target recognition techniques based on micro Doppler phenomenon are popular because they are applicable even on low resolution radars, in contrast to other techniques such as High Resolution Range Profile (HRRP) which need high resolution in range or angle. Usually, main purpose of such techniques is generating robust features against target initial state, velocity, aspect angle, etc. rather than features which exactly identify a target. Main approaches in the literature are based on time-frequency transforms (TFT) such as spectrogram in order to generate features to classify targets, but in this thesis, we propose a totally different method using Recurrence Plot for generating features... 

In this research with Finite Element Methods in ABAQUS, numerical modeling has done in three-dimensions, which can be used to determine the effect of different factors on the surface settlement. Also, various factors such as geotechnical conditions, tunnel diameter,tunnel depth, the impact of the thickness of the segments and the amount of eccentricity of the structure relative to the longitudinal axis of the tunnel considered in this study. Face Pressure Supports, and Grout Injection Pressures are taken into account, too.Tunnel drilling causes a change in the displacement area and creates a changing zone around the tunnel. In this regard, not only adjacent buildings will be affected by... 

After the fisher hypothesis about the relationship between asset returns and inflation, numerous studies tried to examine the accuracy of the hypothesis. Contradicted results continued to the proxy hypothesis by Fama (1981). In this thesis, after a thorough survey of the literature, both theoretically and empirically, in order to find the inflation hedging ability of the land, gold and stock in Iran, we try to find the hedging ability of the assets in Iran. Considering the seasonal characteristic of the data, we employed HEGY (1990) unit root test. Finally, by using vector error correction models we show that in the long run, stock and land hedge the wealth against inflation. In the short... 

In the last 4 years, while the annual investment return on 5 years bank deposits was 25 percent; the total index of Tehran Stock Exchange on average grew by 155 percent. Why the investors are not so willing to invest in the stock market? This research deals with existence of equity premium puzzle in Tehran Stock Exchange. Therefore, the Total Price Index of exchange market is considered as a risky asset and the return on long-term (5 years) deposit is a proxy for risk free asset. Data is monthly and covers the first month of 1380 (Persian Calendar) to the beginning of the second month of 1391 (equivalent to Aug 2010 to Jan 2013); which is converted to real term using monthly inflation rate.... 

An increasing important issue faced by Iranian labor market at the current decade is the job positions which have been occupying by workers who are not match for them. Over the recent past years the supply of college educated labor has experienced a significant increase, while the demand side of the market has shrunk because of low economic growth. This study intends to examine intensity of the over-education on the individuals’ wage By making two alternative definitions for overeducaion namely; realized match and job analysis. To this end we use households’ income and expenditure survey for 2001, 2005, 2009 and 2012 in rural and urban areas. Theoretical background is based on the Duncan and... 

In this study, we intend to investigate the effect of pollution levels on the valuation of residential units in Tehran. The method used in this research is Hadanik pricing method. Data required for the project, in relation to the intrinsic characteristics of housing including number of bedrooms, building life, area and… air pollution index by regional stations on a daily basis and housing environmental characteristics including per capita green space, day and night pollution index, density The population of the area and… are collected. According to the results, they have the greatest impact on determining the value of the building area and building life, and after controlling for other... 

Urban mobility platforms introduced as an innovation in matching suppliers and demanders to each other in the transportation market in recent years. In this research, we applying synthetic control method to analyze the impact of this kind of platforms on labor market variables like work hours, income and number of employed persons in affected activity group. We use the ISIC correspondence tables for versions 3.1 and 4 and also Iran labor force survey and household survey to making activity control groups. The results show that work hours for main work in the related group were reduced. As well as the number of employees in the group increased 100 thousand people and the number of earners... 

In economies with high inflation rates, investors are concerned about their purchasing power and assets’ value. Traders are interested to choose optimal portfolios in terms of risk and return. In recent years, the Iranian stock market and real estate experienced a quiet long period of boom with high rates of return. In this study, we estimate and analyze the equi-correlation between the returns in the markets. For this purpose, we use the monthly data of real estate prices in Tehran and the Tehran Stock Exchange Index for a twenty-four-year period, applying the DCC technique. Our results reveal that the long-term correlation between these two markets is not strong, leading us to suggest them... 

Proton precession magnetometers are one of the most sensitive scalar magnetic sensors. Their function is based on Zeeman effect and also nuclear magnetic resonance phenomena. In this project we have designed and implemented needed coils, swithching and signal detection circuits. Because of extremely high sensitivity of this sensor to induced noises and also gradient of earth’s magnetic fileld, detection of precession signal needs design of low noise electronic circuits with special EMC considerations. The implemented system in this project contains different blocks, such as switching circuit and its related control unit, amplifier, filter and frequency meter. Using this system, the obtained... 

Effective field theory is a practical method for model building and explaining experimental/observational data. These theories are constructed based on knowing low energy degrees of freedom and symmetries (accidental or fundamental). By construction, these theories are applicable up to a cut-off scale and their predictions beyond that are not reliable. For applications to higher energies a UV completion is needed through which modifications are applied or new heavy degrees of freedom are introduced. In order to complete a theory in a Wilsonian approach, scattering amplitudes must satisfy some constraints. These constraints are derived from basic assumptions like Lorentz invariance,... 

Numerous structures which are involved in seismic soil-pile-structure interaction have been destroyed. Considering complexities which exist in soil-pile interaction problems and lack of precise methods without imperfect bases, it is necessary to use numerical methods for analyzing soil-pile interaction problems. In this research, three-dimensional modeling and studying the effect of changing soil and pile parameters on the behavior of pile under earthquake loading is performed using finite difference software, FLAC3D. The soil in this model has a softening behavior. Real earthquake spectrum has been applied into the model as the acceleration time history at the bedrock level. The results of... 

Based on modern finance theory, valuation should not depend on nominal stock prices. However, evidence shows that the nominal price of stocks does matter in the U.S. stock market. In this paper, we examine the effect of nominal share prices on stock returns, using data between 2009 and 2017 form the Tehran Stock Exchange. Our results indicate that there is no significant relationship between nominal price and return on the Tehran Stock Exchange. By controlling for different important variables, the return differential between high price and low price stocks is insignificant and the results are robust to various specifications and tests. Furthermore, by using event study under the market... 

Suction caisson is a relatively new technology which was introduced about 30 years ago for the first time and after several investigations, was found its position in the oil industry and construction of anchorages, during previous decade. So nowadays, it is the most effective and economical choice as the mooring of offshore structures in comparison with the other foundations. Suction caisson is a hollow cylinder with an open bottom and a closed top. After placement on the seafloor, the caisson first penetrates into the soil by its self weight and then inserts into the ground by pumping water out of it. Although many researchers have attempted to understand the behavior of suction caissons... 

Modern communication and space systems such as satellite communication devices, radars, SAR and radio astronomy interferometers are realized with large antenna arrays since this kind of radiating systems are able to generate radiation patterns with high directivity and resolution. In such a framework, conventional arrays with uniform inter-element spacing could be not satisfactory in terms of costs and dimensions. An interesting alternative is to reduce the array elements obtaining the so called ‘ thinned arrays’. Large thinned arrays have been exploited because of their advantages in terms of weight,consumption, hardware complexity, and cost over the... 

Multi-period Value-at-Risk (VaR) forecasting is important for risk management. Financial institutions especially commercial banks according to Basel Committee regulations for capital adequacy in “Internal Approach”, should forecast their VaR for multi-period horizons (longer than one day). The most conventional approach for forecasting multi-period VaR is scaling one-day forecasted VaR that is called “square root of time rule”; therefore most works in this area have been focused on forecasting one-day VaR. In this study, we review performance of a wide range of different methods in forecasting multi-period VaR. The results of our study show that historical simulation performs weakly in...