Sharif Digital Repository

Crumb rubber, produced from shredding of scrap or refused tires, is one of the most commonly used modifiers of asphalt. Asphalt rubber, in addition to mitigating some of the environmental problems of disposing scrap tire, improves the flexural strength of pavement, extends the life of pavement and reduces the maintenance costs. The properties of asphalt rubber are highly dependent on the type and composition of base asphalt, type and amount of crumb rubber, and the production method.The goal of this research is to investigate the performance properties of asphalt rubbers produced from Iranian asphalt and crumb rubber, using an industrially feasible method. The Superpave testing procedure was... 

In this study, thermal and rheological properties of nanofluids of water/carbon nanotubes, water/spherical silica nanoparticles and water/hybrid nanoparticles (hybrid of carbon nanotubes and spherical silica nanoparticles) have been investigated. To do so, carbon nanotubes have been synthesized by CCVD process and spherical silica nanoparticles and hybrid nanoparticles by wet chemical method. After synthesis of nanomaterials, nanofluids have been prepared by using SDBS as a dispersant with the concentration of 1.5 times of concentration of nanomaterials and then thermal conductivity, kinematic viscosity, dynamic viscosity and density of nanofluids have been investigated. As the results show,... 

The transport behavior of water molecules inside a model carbon nanotube is investigated by using nonequilibrium molecular dynamics simulations. The shearing stress between the nanotube wall and the water molecules is identified as a key factor in determining the nanofluidic properties. Due to the effect of nanoscale confinement, the effective shearing stress is not only size sensitive but also strongly dependent on the fluid flow rate. Consequently, the nominal viscosity of the confined water decreases rapidly as the tube radius is reduced or when a faster flow rate is maintained. The effect of ion concentration and temperature rise on fluid flow and shearing stress is also investigated.... 

Modification by crumb rubber is a useful means of improving the resistance of asphalt binders and mixtures against rutting, fatigue cracking, and low temperature cracking. Increase binder viscosity and decrease stability at high temperatures are accompanied by most modifiers, and crumb rubber is no exception. Recent research efforts have shown that development of cross bonds across polymer chains and sulfur can improve the storage stability of modified binders. Also, WMA additives can considerably decrease the binder viscosity. This research showed that addition of small amount of sulfur during the crumb rubber modification can improve the workability and storage stability of this binder.... 

Magnetic resonance imaging is one of non-invasive methods to measure the hemodynamic and morphologic parameters of tissues, especially brain tissues. Hemodynamic parameters monitoring in brain tissue is of significant importance in many majors such as detection of tumor occurrence, brain abnormalities, and track of treatment procedures. Blood is a suspension, comprised of plasma, red blood cells, white blood cells, platelet, etc. Plasma is a Newtonian fluid which is composed of proteins and has a constant viscosity in body temperature. Rheological properties of blood are highly dependent on mechanical and rheological properties of its cells and this dependence is multiplied in narrow vessels... 

For designing a unit operation, knowledge about physical properties is essential. This is attained either by direct measurement, which needs spending time and cost or, using proposed correlations. This project is subjected to theoretical analysis of viscosity as the most important rheological property of dilute suspensions of microgels, or in other words colloidal suspensions of porous spheres. They are applied in drug delivery, enhanced oil recovery, synthesis of catalyst and adsorption of heavy metal ions from aqueous systems for water purification purposes. In dilute suspensions particles are faraway from each other and there is no interaction between them therefore, it is better to... 

In this study, density, viscosity and surface tension of aqueous solution of Sulfolane, ( TEA+TMS+H2O) and (DIPA+TMS+H2O) systems were measured . Density, viscosity and surface tension were measured using pycnometer, Cannon – Fenske viscometer and Capillary rise method, respectively. Surface tension measurements of (DIPA+TMS+water) were carried out by the ring method using a LAUDR TD3 tensiometer,. The experiments were carried out in low concentrations and atmospheric pressure in the temperature range (70 - 30) . The obtained Data was modeled using empirical and thermodynamic models. Density calculation was done using the Setchenov and Redlich – Kister models.and the results indicated that... 

The success of matrix acid production operations and its proper efficiency is one of the main challenges for oil and gas companies. The heterogeneity of the reservoir formation (especially the permeability difference) in the area around the well due to the presence of different reservoir layers results in the non-uniform distribution of acid among them and adds acidizing challenges. In order to improve production conditions, stimulation fluid transfer to the low permeability layer, which is the main target of acidizing. In this study, a new generation of chemical diverter, called Viscoelastic Surfactant, has been used. These materials have two components of elastic and viscous behavior, and... 

In this project, combination of PC-SAFT equation of state and friction theory was used for predicting the viscosity of reservoir fluid. Parameters of PC-SAFT and f-theory are available for pure components, but they are not known for oil cuts that are complex hydrocarbon mixtures. To solve this problem, in the first step, existing optimized parameters for PC-SAFT EOS of hydrocarbon mixtures were used and then, parameters of f-theory for mixtures were optimized. To set the parameters, two approaches were studied. The first approach is to obtain a series of empirical correlations that can estimate the parameters of f-theory (in conjunction with PC-SAFT) for oil cuts in terms of their molecular...