Sharif Digital Repository

In this thesis the dynamic behavior of the thick-walled shell with variable thickness is investigated. Such structures are used in a variety of industries including aerospace, oil, gas and petro-chemistry. In this study, the dynamic behavior of a rotating truncated conical thick-shell with various geometries is investigated. For this purpose, modal analysis is performed using the refined finite element method. Then,the natural frequencies and corresponding mode shapes are calculated for several different geometries. Also, the relationship between geometrical variables such as thickness, the ratio of length to radius, ratio of cross-sectional radius and so on, with the natural frequency of... 

The high consumption of worldwide fossil energy and its detrimental effects on the environment and climate have prompted a transition toward renewable energy sources. The availability of renewable energy sources depends on weather and seasonal changes; therefore, an imbalance between supply and demand would be unavoidable. Hydrogen storage as an energy carrier, can fulfill this energy mismatch. Storing hydrogen in underground formations, such as aquifers, has been the subject of extensive research recently. In these storage reservoirs, hydrogen contacts the resident brine which will be lost through the dissolution-diffusion mechanism. Therefore, successful design of these storages requires... 

During all operations in oil and gas reservoirs, it is possible to cause formation damage. These damages can greatly reduce the rate of production. One of the major damages that can seriously affect the performance of a reservoir is the damage caused by drilling fluid. The main purpose of this thesis is to study the main mechanisms of formation damage caused by water-based drilling fluid using a glass micromodel for the first time. An accurate understanding of the mechanisms of formation damage can provide a good understanding of the selection of the type and concentration of materials used, as well as appropriate methods to control and eliminate damages. for controlling the drilling fluid... 

Various methods have been developed to improve the production capacity of hydrocarbon wells, one of the most successful method is hydraulic fracture. This method, despite improving well production and increasing production levels in a reservoir, causes secondary damages such as water blockage, which is a result of the leakage of fracturing fluid into the fracture matrix and the deformation of the reservoir. This damage can reduce the production rate of a well. Studies prior to this study have mainly examined the damages caused by the leakage of fracturing fluids on a core scale. In most of these studies, damages has been studied only by measuring the pressure and changes in the permeability... 

Formation damage is one of the most important challneges in hydrocarbon production; drilling mud invasion is one of its common types. This damage is caused by the penetration of the drilling fluid into the porous media, which its filtrate and solid pareticles block the pores and cause permeability reduction. The main purpose of this thesis is to investigate the pore-scale mechanisms of the formation damage induced by invert-emulsion drilling fluid and to investigate the effect of adding nanoparticles to the drilling fluid on the severity of the damage using microfluidic technique. According to the latest published articles, there has not been any research conducted at the pore-scale with... 

Considering the world's diminishing oil reserves, as well as the growing demand for oil and energy consumption, Enhanced Oil Recovery (EOR) techniques are becoming increasingly important in the attempt to improve oil production. Engineering salinity waterflooding has gained widespread attention and popularity in the last two decades due to its environmental friendliness, lack of expensive additives, low operating costs, and ease of use as an oil extraction process. The goal of this study is to use an innovative method to develop a mechanistic approach model that simulates and forecasts the mechanism and performance of the engineered water flooding process. Wettability alteration, the most... 

Various studies have confirmed that water salinity and its composition significantly affect the efficiency of the waterflooding process. Field-scale operation of low-salinity water injection has been proven to be a cost-effective enhanced oil recovery (EOR) method which is also compatible with the environmental regulations. Although this method has satisfactory results, it faces some challenges, such as in-situ mixing of the injection low-salinity water with the saline water in the host reservoir. The salinity of the injected water increases, as it contacts the high-salinity reservoir brine in the pores. This phenomenon significantly impairs the efficiency of this technique, and increases... 

The airport terminal is difficult to plan and design due to the different components and the intricate complexity of its parts. At the airport terminal, we face a queue system which simulation is always a good way to analyze. In addition, computer simulation using modern softwares with the capability to model different types of systems, including the airport terminal, while being less realistic than analytical models, is less costly than operational Exercise.In this study, a supportive approach for better and specific management of Iranian airport terminal buildings with discrete-event simulation is proposed, considering the need for managing the airport terminals building in the country and... 

In this project the energy of rotational barrier of C-N bond in 2-cyanoethyl piperidine-1-carbodithioate has been studied by using Dynamic Nuclear Magnetic Resonance spectroscopy. Spectra were taken at various temperatures in two different solvent; acetone and chloroform. For simulation of line-shape broadening SpinWorks software was used. This with two interfaces made possible simulation with two band-shape simulator programs; DNMR and MEXICO. The rate constants obtained from simulations were used for calculation of thermodynamic activation parameters (ΔG#. ΔH#. ΔS# and Ea#). The computational calculations were done by using Gaussian03 in several level and basis sets that are in good... 

The focus of this project was on gaining the knowledge of design characteristics and manufacturing of a hydraulic servo valve. Hence, in the first stage, the model of the valve was considered. After investigating the important parameters which influence the performance of the valve, the effect of each parameter on the valve's efficiency was examined. One of the most important characteristics of the valve is the amount of lapping between the spool and sleeve. Numerical analysis was done and all the characteristic curves were elicited. Equations governing the dynamics of the plant including a servo valve, servo actuator and dynamic model of the turbine and waterway were presented. Then the... 

A mathematical model was developed to assess thermomechanical behavior of work rolls during warm rolling processes of AA2017. A combined finite element analysis-slab method was first developed to determine thermal and mechanical responses of the strip being rolled under steady-state conditions; Then, the calculated roll pressure and temperature field were utilized as the governing boundary conditions for the thermomechanical problem of the work roll. Finally, the thermomechanical stresses within the work rolls were predicted by a thermoelastic finite element approach. The results indicate that, in warm strip rolling, thermal and mechanical stresses developed in the work rolls are comparable....