Sharif Digital Repository

One of the main problems associated with the oil production is asphaltene precipitate in the reservoirs. In order to plan for the EOR methods, production scenario, and selection of completion technology, it is necessary to study the initiation of asphaltene precipitation called onset. Since the experimental methods is not only is so expensive and time consuming, the required materials are not available. Consequently, modeling approaches as new methods are proper substitutes for laboratory procedure. These methods need less costs and time and higher accuracy compared to the experimental investigations which are the advantages of these methods. Computational operations for onset determination... 

Today due to increasing demand of using energy and petroleum products, finding optimum ways to produce more oil and gas in a way which petroleum reservoirs faces less pressure drop is very necessary. Therefore, petroleum engineers face multiphase flow proportionally more than other issues. So, they have to comprehend this issue in a complete manner in order to discover the best practical ways for maximum utilization. Researchers in different ways tried to model multiphase flow, but many of provided models are so complicated and sometimes have low accuracy. In this project we tried to present a model that in simplicity has high accuracy and works in a way that apperceiving it, is very... 

This research empirically examines the hydrodynamic performances of squat submarines under the resistance and wave tests, besides the numerical investigation of pressure drag reduction techniques. Submarines are limited for public use due to military classification issues and being expensive. This research introduces a new squat submarine in order to enable underwater exploration. This squat submarine has a 9- person capacity as a manned midget submersible using specific geometries of length-over-depth ratios (L/D) below four. The cause of such selection is to provide better visibility for the passengers to research and explore the sea. However, the geometrical features considerably change... 

Problems with the mitral valve can make the heart less efficient at pumping blood around the body. Severe problems can lead to heart failure if the valve is not surgically repaired or replaced. A simple approximation of the heart geometry is used and the valve dimensions are based on reported measurements. The primary objective for this study is to design and simulate the opening and closing behavior of the mitral valve using 2D fluid-structure interaction (FSI) model using ADINA software in order to evaluate and investigate the hemodynamic performance and problems of mitral valve, in which the blood is described as a viscous incompressible fluid, and the mitral valve is described as an... 

The effect of using backpressure of air injection in a microchannel on internal flow pressure drop were investigated in this study. Multiphase flows are commonly encountered in gas and oil industries. Flow fields in production operations are often complex and include multiphase flows of gas and liquid. Previously, because of their complex nature, these flow patterns have been mostly investigated only experimentally and empirical correlations based on the experimental data. From another point of view, it is almost impossible to experimentally realize all the flow conditions for each of the flow patterns. Nowadays computer facilities provide the tool to construct and use large-scale... 

In recent years, leg pain is a consequence of inappropriate foot movement, which is an important health problem for us today. The health problems of the foot and the waist are due to wearing inappropriate footwear that is not designed for different activities. For example, Walking, long-standing on the feet, cycling and so on. A shoe insufflator is not suitable for walking, cycling, and standing. For designing an appropriate shoe insole for different activities, it is important to have a force determination profile for each person. This means that the insoles design shoes should be personal. A low-cost device has been designed, which can be used to measure the pressure on the sole of the... 

This project studies the effects of different blade and different velocity fields on reducing drag coefficient. A numerical simulation was set up for a circular cylinder to represent the effects of blade on reducing drag. In this study, velocity, density and the cylinder diameter were constant and different viscosities were selected for different regime flows. The computational fluid dynamic programmer FLUENT was used to simulate results for this project. Arrays of cylinders were set up to see the changes in velocity profiles and drag coefficients for a range of Re. In this study, I studied three cases of setting up blade and concentrated on friction drag coefficient and pressure drag... 

Insulin pump treatment is considered the most physiological way to imitate the healthy body's insulin profile in patients with diabetes. They provide a precisely controlled rate of insulin delivery to diabetic patients who would normally need multiple daily injections to regulate blood glucose levels. The firmware allows numerous modifications to the bolus dose and basal rate to enable patients to manage insulin levels in response to events such as eating, sleeping, and exercise.
In this Study, we have first investigated different models of insulin pumps on the market and chose the Spring ZoneTM insulin pump model for our study due to its innovative technology. This pump employs a... 

MPD technique manages drilling pressure to keep bottom hole Pressure balanced in the well. The objective to this studs, is to approximate the well pressure to formation pressure to prevent entry of fluid into the well. MPD is a new method drilling in which, driller controls the annulus pressure in order prevent drilling problems. the circulating fluids system employed by MPD technology is more akin to that of a pressure vessel. In this thesis, using in laboratory-made machine, reacts with sudden changes in pressure at the bottom hole in the shortest possible time. Basically, this system is a system where well bore pressure management is obtained by adjusting the pressures along the well bore... 

In this report the important factors affecting the levitation melting of copper are discussed. Pure copper nanoparticles were synthesized by utilizing an Electromagnetic Levitation Melting Gas Condensation (ELM-GC) method. Pure bulk copper samples were melted and evaporated by electromagnetic levitation technique in an inert gas atmosphere in a silica tube. Copper nanoparticles were formed from ascending vapor by employing high purity argon and helium as carrier gases and cooling agents. The pressure of inert gas was changed in both helium and argon atmospheres to investigate on pressure’s effect. Particle size and morphology of the produced nanoparticles were studied by Field Emission... 

In this thesis its considered the characterization of an ultrasound wave in a medium with some obstacles. Derivation of speed of molecules and pressure of the wave is carried out in the Cartesian coordinates system. Simulation is carried out to prove the dependency of wave speed to set up parameters such as the target point (x,y,z) at which the speed value is obtained, the location of the obstacles, the amplitude of original wave emitting from the source, and the propagation speed in different layers of the medium. From the numerical results, it is apparent that the amplitude of the speed wave gets degraded as the wave travels through the medium which is a function of reflection and... 

Lakes, marshes, and wetlands shrinkage and drying up due to natural and human driving forces is today one of the most important concerns in the world. Mahaarloo Salt Lake in southern part of Iran is (18 km far from south eastern of Shiraz ) drying-up and is faced with ecologic and environmental degradation. It recharges from western north by upstream basin of Shiraz and 3 rivers named Khoshk, Chenaarrahdaar, Soltaanabad and also from eastern south by Nazarabad river located in Sarvestan basin (Regional water org. of Fars 1382). In recent years, the shrinkage of Mahaarloo has been exacerbated by mismanagement of water resources, inappropriate land use, ignoring allocation of environmental... 

This project presents an outline of the crack tip stress fields in the presence of a plastic enclave around a growing fatigue crack using RKPM and Drucker-Prager criterion for pressure sensitive materials such as concrete and rock. Two distinguished features of RKPM are the arbitrarily high order smoothness and the interpolation property of the shape function which has kronecker delta property at the associated nodes. This method has proved to handle extreme material deformation and moving discontinuities. For the frictional materials such as rock in geotechnical engineering, a non-associated or associated Drucker- Prager plasticity model is appropriate for modeling its constitutive... 

The constitutive modeling of material is clearly a keystone of successful quantitative solution possibilities. No finite element code will provide results of better quality than that of the constitutive equation implemented in it. In this study, a nonassociated three-invariant cap plasticity model is presented for material under compressive stress. Generalized single-cap plasticity is developed which is based on the hardening-softening material functions. The hardening functions are consisted of isotropic and kinematic parts. Using the definition of yield surface, material functions and nonlinear elastic behavior, as function of hardening-softening parameters, the constitutive elasto-plastic... 

Acceptance of new technologies in an industrial field generally takes a long time, and needs accelerators and facilitators to be thoroughly and truly understood, accepted, and then implemented. One of the most useful accelerators is Feasibility Study, which help the specialists to be confident that the whole technical and economic aspects of the issue are considered in an overall view and the technology is totally feasible and beneficial.Managed Pressure Drilling which was introduced as a new technology to drilling industry internationally in 2003 and developed rapidly till now, is one of the most useful technologies in the oil and gas wells drilling industry, and helps the Operator... 

Purpose of this thesis is to discover the governing equation of Flying Wing aircrafts. In Flying Wing aircrafts crew, payload, fuel, and equipment are typically housed inside the main wing structure. A clean flying wing is sometimes presented as theoretically the most aerodynamically efficient (lowest drag) design configuration for a fixed wing aircraft. We assume Flying wing as plate. Achieve structural formulation needs to use modal deflections and put them in Lagrangian equations. In the right had side, pressure on flying wing can be found. To obtain air pressure on flying wing in this thesis, applying Quasi steady aerodynamic and Howe distribution is necessary. Applying this method on ... 

In a nuclear power plant, transients are initiated for various reasons such as equipment failure or external disturbances. A transient should be identified as quickly as possible so that countermeasures can be taken to reduce its negative consequences. Due to the large number of parameters that can be monitored in nuclear power plants, the time limit for interpreting the information, and the stressful conditions of the incident, it will be very difficult to detect transients by the plant operators. Therefore, the development of operator support tools to identify transients is of great importance in the safe operation of nuclear power plants. Various studies have shown that data-driven... 

Selection of appropriate thermohydraulic tool for analyzing nuclear reactors is a trade of between accuracy and calculation run-time. Nuclear reactors analyses perform on two levels including system and sub-channel. In this regard or the system codes' one-dimensional approach is selected or the CFD codes for considering the three-dimensional and non-equilibrium phenomenon are employed. In this research a T-H tool for prediction of light-water cooled reactors core is developed. Although this code requires lower CPU and run-time in comparison with CFD codes, in contrast with system codes can report non-equilibrium and three-dimensional phenomenon. This code has a modular implementation based... 

In nuclear power plants (NPPs), the integrity of the Reactor Pressure Vessel (RPV) is one of the most essential issues in assessing the life of the NPPs. The RPV in a nuclear power plant cannot be replaced during plant life. Hence, maintaining the integrity of the RPV nuclear power plant is of great importance. In this study, the RPV integrity of Boshehr Nuclear Power Plant (BNPP) gainst crack formation and growth in the case of LBLOCA is evaluated and studied by the finite element method (FEM) in ABAQUS using the J-Integral method and also the weight function, which is a function of crack shape. According to the results, stress values increased significantly during the LBLOCA incident. The... 

According to Iran’s energy policies, the natural gas transmission pipeline has expanded significantly over the last decade. Moreover, improving energy efficiency is known as a key strategy in energy policies and programs. Therefore, the need for expansion and development of the rational use of energy has received more and more attention. The use of technologies aimed at energy recovery will be an effective step in this regard. Pressure regulators are most commonly used to reduce this pressure in Iran as one of the significant sources of exergy destruction in Iranian gas transmission system. The turbo-expander system is a kind of technology applied in gas pressure reduction stations to...