Sharif Digital Repository

An understanding of the effect of degree of cementation on static behavior of cemented soils in becoming increasingly important in design and analysis of geotechnical engineering problems. Naturally cemented coarse-grained soils are widely present in many parts of the world. Misunderstanding of the behavior of such soils could lead to under or overestimate of the soil parameters. Previous studies conducted by Prof. Haeri and his co-workers show that most of the alluvial deposit of Tehran, the capital city of Iran. The amount and characteristics of the cementation of the deposit varies in different parts from highly cemented in the north to non-cemented in the south. This deposit consists of... 

Oil reservoir simulation serves an important role in forecasting oil production. This forecast, in turn, helps to devise a production scheme for hydrocarbon reservoirs which is one of main objectives of reservoir management team. In this research, using the idea of logarithmic distribution of reservoir fluid pressure around a wellbore, a new method for simulation of naturally fractured reservoir is developed. This method is shown to be more fast and accurate than conventional methods in reservoir simulation. In this method Dual-Porosity formulation is used for description of fluid flow in fractured reservoirs. The governing equations then were discretized by Galerkin Finite element method in... 

In this project, investigation of C-N internal rotation in ethyl tetrahydro-1(2H)-pyridine carbdithioate and ethyl 1-pyrrolidine carbodithioate were investigated by dynamic nuclear magnetic resonance spectroscopy. The 1HNMR and 13CNMR spectra were taken at the variable tempratures around the coalescence temprature. Thermodynamic parameters were calculated by analysing the spectra and the outcomes were compared by the theoretical results. For ethyl tetrahydro-1(2H)-pyridine carbdithioate ∆G‡ was 14.3 (kcal/mol) and for ethyl 1-pyrrolidine carbodithioate ∆G‡ was 17.0 (kcal/mol) which were in accordance with the theoretical results. The analysis were done by the Spinworks program which... 

Although CO2 is an environmentally benign solvent, many organic solutes are only sparingly soluble in CO2. We use Monte Carlo simulations in the context of statistical perturbation theory, Widom’s particle insertion and expanded ensemble techniques in order to investigate the molecular properties involved in enhancing the solubility of materials in CO2. Our Monte Carlo simulation of diluted methane and its fluorinated forms showed that substitution of H atom with F atom, results in more favorable solvation, but with further increase of F atom (after CH2F2) due to small size of solute it is impossible for all CO2 molecules in the first solvation shell (FSS) to have a good orientation against... 

Well-Testing is a one of the usual methods in petroleum engineering for evaluating reservoir and well parameters. This method is based on measuring downhole pressure verses time in different production conditions and then drawing these data in different pressure-time graphs and evaluating reservoir characteristics and calculating reservoir parameters. This thesis describes the development of techniques for the automation of the model identification and parameter estimation of a well test interpretation, using Artificial Intelligence. The computer programs which are written in MATLAB software use Neutral Network toolbox to detect a model that is based on the pressure derivative curve, and... 

Permeability is an essential parameter used for reservoir evaluation, simulation and management to optimize oil recovery. The conventional approach to estimate reservoir connectivity, conductivity, sweep efficiency and other critical information for decision-making is to build detailed geological models, which are then upscaled to a coarser grid where flow simulations are run. However, this takes many hours to be carried out even for a single realization practically. In practice, a very small number of realizations are considered and consequently the true uncertainty in the results is very poorly estimated. In this study, a statistical model of isotropic overlying sandbodies is used to... 

VAPEX is a relatively new EOR process for the recovery of heavy oil. In this process solvent is used to form a vapor chamber within a reservoir. Vapor dissolves in the oil and diluted oil drains by gravity to a horizontal production well. The essential features of this recovery mechanism have been discussed in this study. Furthermore, a semi-analytical and a simulation study of VAPEX process have been performed on a specified Iranian heavy oil reservoir (such as Kuh-e-Mond). The aim of this study is to investigate an exponential functionality (correlation) witch incorporates all physical parameters that affect the production rate of VAPEX process in dimensionless form. The adjustable... 

The main power source of many space systems, are solar panels which are mainly affected from irradiance, temperature and particles radiation and an electronic solar panel simulator is a power-supply system that simulates the output of the solar panel. This system by processing of input data such as environment conditions, panel specifications and etc, simulate panel behavior and it can set the IV curve of the panel in different conditions. In this thesis, after introducing electronic solar panel simulators (chapter one), photovoltaic cells (chapter two) and space environment and its effects on space systems (chapter three), modeling solar panel based on the equivalent circuit of a solar... 

Part 1: Techniques of production data analysis for single-phase oil and gas reservoirs have advanced significantly over the past few years. These techniques range from traditional (Arps and Fetkovich) to modern (they account for the variation of operating conditions at the wellbore). Although the production data analysis methods are used generally for single phase reservoirs, the application of these techniques for analysis of production data of a gas condensate reservoir may not yield the reliable answer due to the fact that the flow of fluid in gas condensate reservoirs is not single-phase. This study presents the treatment of the modern methods of production data analysis (single phase... 

In this project, 13 C nuclear magnetic shielding constants and also hindered internal rotation about C-N bond in compound 4 -(phenylacetyle) morpholine are investigated The Factorial Design method was used to obtain the best solution for chemical shift computations and comparison made out in two levels (HF and B 3 LYP). Consequently the (B 3 LYP) method own better data. 13 C NMR Spectra were taken at variable temperature ,and then with simulation of bandshape broadening pattern at coalescence region ,rate constants of exchange were obtained for all temperatures. For simulation of line-shape broadening Spinworks software was used, that with two interfaces made possible simulation with two... 

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... 

Spinal Column is one of the most important parts of musculoskeletal system. Injuries in this region are so rampant and causing vast expense. Risk factors related to spine injuries included personal related ones such as, age, sex, muscles’ strength and career related ones such as body positions at work place and loads. Since in vivo measurements have many restrictions, developing biomechanical models that simulate the response of a person to given loads and conditions has important role in preventing injuries and improving working conditions. Inputs to current models of the spine are considered to have mean value, therefore muscles’ forces and other outputs of these models have single value... 

Members of Centaurea species are common traditional medicines throughout the world. For this reason medicinal plants are the targets of intense Phytochemical studies. In this research we have investigated Centautea Golestanica which are members of this genus and endemic of Iran. In this research, One Flavonoid, two Sesquiterpenelactones and two triterpenoides were elucidated by advanced spectroscopic techniques such as IR, MS, 1H NMR, 13C NMR and 2D NMR. In continuation of this research, we have reported new and efficient methods for the synthesis of hitherto unknown indole-annulated pentacyclic indolylhydroisoquino lines and naphthooxazocines via tandem dinucleophilic addition of... 

Pile foundations suffered severe damages during the past earthquakes in all around the world. These damages were more severe in laterally spreading grounds and they mostly have been observed in gently sloping grounds and coastal areas. In these cases, Pile foundations not only are subjected to structures inertial loads and kinematic loads of liquefied soil but also lateral spreading intensifies damages. Thus, in the recent decade, several researches have been conducted to investigate the behavior of pile foundations in liquefiable and laterally spreading grounds, however, some uncertainties still remain in modeling of soil-pile interaction. In this study, the effects of liquefaction- induced... 

Nowadays, modeling the behavior of materials during forming processes is so important. The role of most of them is to investigate and predict the evolutions of microstructure and mechanical properties of materials during plastic deformation. Previous researches have demonstrated that the best parameter to investigate these evolutions is the dislocation density of materials. In this study, first, the dislocation-based models, which investigate the material parameters evolutions during plastic deformation, were investigated and it was revealed that among all presented models, only the two internal variables models can investigate the behavior of materials during severe plastic deformation. ... 

Thermodynamic modeling is a useful method for predicting of asphaltene precipitation due to various reasons, such as CO2 injection, mixing of different oils in oil storage and pressure changes. However, the application of solid model and thermodynamic micellization model, for prediction of asphaltene precipitation under gas injection condition, hasnot been improved. In this work, two computer codes which are based on two different asphaltene precipitation thermodynamic models, 1-Thermodynamic Micellization Model and 2- Solid Model, have been developed, and, used for predicting of asphaltene precipitation data reported in the literature as well as the experimental data obtained from high... 

It is widely accepted that under reservoir conditions there exists some degree of block-to-block interaction that may lead to capillary continuity. The formation of liquid bridges causing capillary continuity between blocks will significantly affect the ultimate oil recovery. However, accurate modeling of the growth and detachment of traveling liquid bridges which causes capillary continuity between blocks remains a controversial topic. In this work the generalized continuity and momentum equations along with fracture capillary pressure are combined to develop a mechanistic model for formation of traveling liquid bridges between blocks. Firoozabadi and Ishimoto (1994) model is considered for... 

Increasing the global demand for energy and decreasing the production rate of oil reservoirs have forced the oil companies to focus on enhanced oil recovery (EOR) extensively. This paper summarizes the design, reservoir simulation, and results of different gas injection scenarios in one of the Iranian complex oil reservoirs. This complex reservoir is located in the south west of Iran and is made up of sandstone, limestone, and dolomite layers. It is an under saturated reservoir with no gas cap but with a strong aquifer. Oil production has started in 1977, but due to strong aquifer the production is still in the plateau period. In this study, by simulation, it is estimated that natural... 

Loads from laterally spreading ground have been a major cause of damages to pile foundations in past earthquakes. Analysis of case histories have shown that damages are particularly intense when a nonliquefiable surface crust layer spreads laterally over underling liquefied layers. In this research the effect of lateral spreading due to liquefaction on single piles embede in a gently sloping ground has been investigated. Finite element method using OpenSees is used to model the pile and embedded soil. The soil profile for all models consisted of a nonliquefiable crust layer overlying loose sand with Dr = 30-35% overlying dense sand with Dr = 70-80%. The effect of geometric properties such as... 

Iranian Power industry has undergone fundamental changes since deregulation started in 2003. Currently, bulk trade of electricity in the industry is mainly conducted through a day ahead wholesale market, representing over 98 percent of the exchange of electricity within the grid. Although the current market regime is under operation for over 4 years, several political, cultural and operational obstacles have hindered effective evolution of the restructuring process. Low political support from privatization of the industry assets backed by lack of confidence and trust in market economies in general, and low economic incentive of the market players has slowed down formation of an effective...