Sharif Digital Repository

Studying the dynamics of vesicles in simple shear flow is the first step to decipher the dynamics of cells in flows or the motion of vesicle-based nanoparticles in vessels for drug delivery. The deformation of vesicle in shear flow changes the permeability of its membrane and may lead to its rupture, both of which correlate with the transportation of vesicle cargos to their environment, especially important in drug delivery. The deformation of vesicles in shear flow not only depends on the physical properties of the whole system, such as temperature, but also on the mechanical properties of three media: vesicle membrane plus vesicle’s inner and outer fluid. The effect of the mechanical... 

In this study, polyoxometalate (POM) intercalated in the layered double hydroxide (LDH) was synthesized by a selective ion-exchange method. For this purpose, the nanocluster [VW12O40]3- was immobilized on the Mg2+/A13+/Cl–LDH support. The heterogeneous catalyst was characterized by FT-IR, XRD, SEM and analysis of ICP. The LDH-POM was applied as a catalyst in efficient oxidation of sulfides to sulfoxides using UHP as oxidant and CH3OH/ CH¬2¬Cl¬2 ¬as a solvent at room temperature, as well as epoxidation of olefins using TBHP as an oxidants and C¬2H4Cl2 as a solvent in 84°C. This catalyst showed excellent catalytic activities for a substrate/catalyst ratio (200:1). For example, this catalytic... 

Distinguishing the structure of DNA is of outmost importance in the medicine and agriculture industry nowadays. Various methods have been suggested so far; however, high costs, incorrect results, and time-taking process are among main defects of them. Scientists try to find new ways for recognizing DNA structure and system in order to overcome such problems. One of these new methods is absorbing and passing DNA through Nano-pores in an electrolyte solution under the influence of an electrical field. The basis of this method is the ionized currents which occur due to the passing of DNA through Nano-pores. Because each DNA base pairs can form a barrier corresponding to a unique measured value,... 

In this thesis, the star formation history and evolution of IC 1613 dwarf galaxy and NGC 5128 giant elliptical galaxy has been studied. About IC 1613, our result shows that the star formation history of the galaxy is roughly constant in 5 Gyr ago and this support that the galaxy had been isolated at least in 5 Gyr ago. About NGC 5128, we can see that the star formation rate has suddenly increased in 700 Myr and 3.5 Gyr ago. This results in very good agreement with literature support that the galaxy has experienced some mergers with smaller gas rich galaxies  

This paper studies and compares the effect of "Dutch disease" in Iranian economy in two periods of rising oil price (1973-1978) and (2004-2010). The study presents a DSGE model to analysis the behavior of economic variable in both periods and to address this question that whether or not policy maker has learning behavior. The model consists of households, final goods producers who divided in tradable goods and non-tradable goods sector and the government. I use calibration methods to estimate models parameters.Comparison of simulated results and the actual macroeconomic variables in Iran during 1338-1390 indicates that, first of all Dutch disease effect occur in both periods of oil shock so... 

One of the major reasons causing cracks in external surfaces of concrete arch dams are thermal loads. Therofore, in order to avoid instabilities due to function of thermal loads in association with hydrostatic and hydrodynamic pressures, a precise evaluation of temperature distribution through dam body is indispensable. In this study, effects of thermal loads mostly on upstream surface of Karun-3 concrete arch dam in Iran were examined using a 3-D finite element method considering water level fluctuations. Also the influence of operatvie boundry conditions in our problem which are water temperature, air temperature and solar radiation was precisely taken into account. Moreover, nonlinear... 

The classical economic batch quantity (EBQ) model assumes that all produced items have a perfect quality. But in real-life production systems, generation of defective items is inevitable. A portion of these defective items is considered to be scrap , while the other is assumed to be reworkable and reworking them can reduce costs and increase productivity. In this thesis we have studied the economic batch quantity for a single stage production system with rework and scrapping . We want to satisfy the customer demand and minimize total costs of the system like set up costs , production costs , rework costs , holding costs , shortage costs and scrapping costs . In the first chapter of this... 

The behavior of pile foundations under earthquake loading is an important issue that affects the performance of structures. Design procedures have been developed for evaluating pile behavior under earthquake loading; however, the application of these procedures to cases involving liquefiable ground is uncertain. The performance of piles in liquefied soil layers is much more complex than that of non-liquefying soil layers because not only the superstructure and the surrounding soil exert different dynamic loads on pile, but also the stiffness and shear strength of surrounding soil diminishes over time due to both non-linear behavior of soil and pore water pressure generation. In this... 

In this thesis, based on the taking-off and landing of aircraft with GE 21-J85 turbine, the low cycle fatigue (LCF) test for superalloy used in first stage blades is considered. The LCF tests were performed on both coated and uncoated Rene 80 which are used in GE 21-J85 turbine at R = (min/max) = 0, strain rate of 2 10-3 s-1 and 760oC, 871oC and 982oC. To produce specimens, an investment casting method was used so that adequate amount of polycrystalline round bars could be obtained. The specimens were all homogenized and solution treated. After the inspection, some specimens were coated with pack cementation method in CODEP-B powder in H2 atmosphere. The coated and uncoated specimens all... 

In this thesis, two-level optimal control of uncertain and non-uncertain large-scale systems is presented. In the proposed two-level approach, using a decomposition/coordination framework, the large-scale system is first decomposed into several interactive subsystems, at the first-level, where a smaller optimization problem is solved at each subsystem. At the second-level, a substitution type prediction method, as a coordination strategy, is used to predict the interaction between subsystems. The coordinator mainly evaluates the next update for the coordination parameters and continues to exchange information with the first-level, so that the overall optimum solution is obtained. It is shown... 

In this study a layer with compressive residual stress was created by severe shot peening and hence surface grains was changed to nanostructure. Fatigue life will be increased as a result of compressive residual stress. Surface roughness increase, is one of the disadvantages of severe shot-peening process. Re-shot-peening with the smaller shots and lower intensity is proposed for reducing surface roughness. Numerical simulation as a powerful method, used to investigate the effects of shot-peening parameters on the residual stress distribution, surface roughness and grain size. Obtained results indicate that more energy in process can improve residual stress distribution and grain size unlike... 

A special steel beam-to-column connection, named Khor-jini, is commonly used for steel framing system in Iran. In this system, two continuous beams are passed next to the columns and are connected to the column side using seated brackets.This type of connection has been common in Iran from the late past. Unfortunately, the seismic behavior of Khorjini frames had not been sufficiently studied prior to Manjil Earthquake of 1990. Due to very large damages which occurred in steel structures especially in connections during the said earthquake, the seismic behavior of this type of connection was studied and some of its weak points were recognized.In this study non-linear... 

Due to the growing need for plasmonic wavs in microwave and terahertz spectra, a periodic arrangement of one-dimensional cut-through slits is investigated and an equivalent model based on the effective medium theory is derived. In contrast to the all previous attempts that were successful in mimicking only the zeroth-order diffracted waves, the proposed effective medium is capable of mimicking all diffraction orders. The parameters of the equivalent model are established by comparing the scattered waves of the semi-homogeneous medium and those of the main structure obtained by invoking the rigorous mode matching approach based on the single mode approximation inside the slits. This medium is...