Sharif Digital Repository

Concrete gravity dams are structures of much importance which their failure due to earthquakes results in a catastrophe. Therefore, precise stability analysis of these types of dams against sliding and overturning is essential. The common method of safety assessment of gravity dams is based on limit equilibrium method assuming that dam slides and overturns as a rigid structure. Although providing high safety factors is somehow acceptable to meet the safety requirements of dams, it should be considered that the whole system of dam body and foundation is flexible in reality and its performance should be studied in this case for stability analysis. In this investigation, first, stability... 

The aim ofthis work is constructing a dye laser pumped in visible spectrum by a second harmonic of aNd:YAG laser.For this purpose, 12mJ of its energy focused by a cylendrical lens into a dye cell. Instead of usual telescope, making aberration in two dimensions, we have used multi prism beam expander to eliminate aberration and also expand beam beyond 10 times. The more magnification resulted in narrowing laser linewidth and it was about 2 nm for two prism beam expander and 0.5 nm for four prism beam expander.
Beam expander configurations were designed in zero dispersioncondition.Therefore,scanning laser spectrum becomes possible. The wavelength was scanned between 565 nm to595 nm, and... 

Today in many industrial sectors, technology has made significant progress. Investing in advanced manufacturing technologies, especially computer integrated manufacturing systems is essential in order to survive in a competitive environment, improve performance, response to demand fluctuations and increase customer satisfaction. With available technologies and systems in computer integrated manufacturing (CIM) and its related technologies, the application of CIM in manufacturing enterprises is a reality and can meet the need of complicated manufacturing environment. Implementation of these systems brings many tangible and intangible benefits. But, according to several factors that must be... 

The purpose of this project is investigating the effect of cross flow and electric field on a liquid simple-jet experimentally. In this research the effect of parameters such as liquid to air momentum ratio, electric field on jet trajectory, penetration and the lenght of breakup point with respect to the jet outlet were studied. The air was produced by a blower in a duct with square test section of 8 cm sides. The air velocity varied from 1 m/s to 11 m/s. Liquid ethanol was injected into the duct with a needle with outer diameter of 0/62 mm and inner diameter of 0.4 mm and 28 mm length. The velocity of jet was 0/62 m/s while the change of liquid to air momentum ratio was from 3 to 260 The... 

This paper examines the effects of institutional price pressure caused by severe inflows and outflows of capital by studying mutual funds transactions in the Iranian stock market between 2010 and 2017. According to the findings, mutual funds that experience severe outflows tend to reduce or eliminate existing positions in their portfolios, which creates a severe price pressure in the securities held by distressed funds. This price pressure caused by a severe outflow of capital leads to decrease stock prices below their intrinsic value. So investors who buy shares that sold by mutual funds earn abnormal returns for providing liquidity. On the other hand, funds with severe capital inflows tend... 

In just a decade, perovskite solar cells have emerged as the next generation of photovoltaic technologies due to their high efficiency, low manufacturing cost, and easy fabrication methods compared to silicon solar cells. To date, highly efficient perovskite cells (with an efficiency of approximately 25.5%) have been fabricated on small substrates by a spin-coating process. In the spin coating process, perovskite precursor is spread on the substrate through shear force. However, the reproducibility of the cells coated with this method varies between research laboratories. Furthermore, since the solution is wasted during the deposition of the perovskite precursor on large substrates, a... 

One of the most common problems encountered in multivariable systems is the interactions between the system inputs and outputs. Interaction causes difficulties in control of these systems. Hence reduction of interaction in multivariable systems is an important design objective. One way to do this is to employ a pre-compensator in the open loop systems. Several approaches with different design methods and optimization criterions have been proposed thus far. In this study the problem of interaction reduction for a square stable system is considered and a pre-compensator matrix is designed which reduces interactions in the interacting multivariable system.In this case the purpose is to use... 

Water flooding is known as a common method to maintain reservoir pressure/enhance oil recovery. The major problem in this process induced from inorganic deposits that caused formation damage around wellbore region. It is due to incompatible nature of injected and formation water which results in permeability reduction and well productivity decrease. Solving this problem is an important issue in the petroleum industry. BaSO4, CaSO4 and SrSO4 are inorganic sediments formed in this process. The physical model of water transport in reservoir and scaling damage due to sediments contains at least two dominant parameters; the kinetics coefficient that specifies the velocity of chemical reaction,...