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... 

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... 

Heat transfer to combustion chamber walls is an unwanted phenomenon. Reduction of this heat transfer by using bidirectional swirl flow, as proved in past studies, can result in time and cost saving methods in design and fabrication of combustion chambers. Bidirectional Swirl flow, existing in vortex engine, maintains the chamber wall cool. This characteristic of such flow field, among with many other advantages for it, makes researchers more interested in studying the propulsion of it as well as its other applications. Bidirectional swirl flow in liquid fuel ramjet engines has the proven advantage of keeping the combustion chamber walls cool and in solid fuel ramjet engines in increasing the... 

Determining the best location for new wells is a complex problem that depends on reservoir and fluid properties, well and surface equipment specifications, and economic criteria. Various approaches have been proposed for this problem. Among those, direct optimization using the simulator as the evaluation function, although accurate, is in most cases infeasible due to the number of simulations required. This study proposes a hybrid optimization technique (HGA) based on the genetic algorithm (GA) with helper functions based on the polytope algorithm and the neural network. Hybridization of the GA with these helper methods introduces hill-climbing into the stochastic search and also makes use... 

Initial static shear stress caused by slopes or nearby structures' foundations can affect the behavior of the soil which is concerned many investigators during previous three decade. In this investigation, the effect of initial static shear stress on the liquefaction resistance of Babolsar sand has been probed using cyclic simple shear tests. Three different initial relative densities (Dr0=20%, 40% and 60%) and three different initial normal stresses (σv0= 50, 150 and 250 kPa) were considered in tests and four various initial static shear ratios (α) ranging between 0.0 and 0.3 were applied which leads to more than 190 distinct experiments. All tests were conducted under constant volume and... 

In this research, the effects of Rayleigh waves on the response of typical three-dimensional concrete faced rock-fill dams (CFRDs), considering dam-foundation interaction and spatial variability of earthquake ground motion are investigated. The time history of Loma Prieta earthquake (Gilroy 1 station) is used as input excitation. The dam is considered to be located in a prismatic canyon with trapezoidal cross-section. A substructuring method, in which the unbounded soil is modeled by the scaled boundary finite-element method (SBFEM), is used to obtain scattered motion and interaction forces along the canyon. Non-linear model is used for rock fill... 

Networked computers are expanding more and more around the world, and digital social networks becoming of great importance for many people's work and leisure. Emails, Weblogs and Instant Messengers are popular instances of social networks. In this thesis, the main target is to have an advertisement according to user favorites and interests by mining his/her interactions in digital social networks. Briefly, in our method social network users are categorized based on the topics exchanges between them in the network, these topics discovered by mining of flowing data in that environment, considering that these topics shows the user willing, finally relevant advertisements will be represented to... 

In the modern world of software engineering, software evaluation has earned a special position. The presence of consultation companies in evaluating the software will confirm this specialty. Web technology, as a new trend in computer science, has attracted the attention of many researchers and practitioners. As known nowadays, most of the software solutions are Web-based. Such software is technically called Web application. The methods of evaluating Web application include the use of traditional metrics in software engineering. The intelligence of the Web in computer science has been the core of much research.
This study is intended to use intelligence, as one of the new features of the... 

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... 

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. ...