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mohammadi--mohsen
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Effects of Static Shear Stress on Liquefaction Strength of Babolsar Sand Investigated under Cyclic Simple Shear and Static Triaxial Tests
, M.Sc. Thesis Sharif University of Technology ; Haeri, Mohsen (Supervisor)
Abstract
Soil liquefaction is a phenomenon in which soil loses much of its strength or stiffness for a generally short time but nevertheless long enough for liquefaction to be the cause of many losses. Thus, many researchers have worked on the factors which affect this phenomenon. Effects of initial static shear stress on liquefaction strength of loose and medium dense Babolsar sand specimens were investigated in this study. Babolsar sand is fine to medium uniform sand classified as SP in USCS. Tests were performed with cyclic simple shear and static triaxial devices. All tests were performed under consolidated undrained conditions. Cyclic simple shear tests were performed under constant vertical...
Analysis of Conductivity between Two Points (Wells) in 2D Conventional Reservoir Models with Percolation Structure
, M.Sc. Thesis Sharif University of Technology ; Massihi, Mohsen (Supervisor)
Abstract
The nature of fluid flow in hydrocarbon reservoirs is very complex because of the complicated sedimentary processes. Proper modeling of distribution of these heterogeneities is crucial, affecting all aspect of fluid flow. The conventional approach to investigating the impact of geological uncertainties on the prediction of reservoir performance is to build a detailed geological model using geophysical, geological and petrophysical data, upscale it and finally perform flow simulation. Because of uncertainties in the data, it is necessary to construct a number of possible geological models and then run flow simulations many times to get a reliable model. This approach is computationally very...
Agile Flight Vehicle Roll Autopilot Design for Reducing Channels Coupling Effects
, M.Sc. Thesis Sharif University of Technology ; Fathi, Mohsen (Supervisor)
Abstract
In this project roll channel autopilot of an agile flight vehicle has been studied. In skid-to-turn tactical flight vehicles according to the type of control strategy, for achievment of acceleration commands, the roll angular velocity should be kept near zero. In usual autopilot design, effects of channels on each others is ignored. But three channels of agile flight vehicles have some mutual effects, that consists of kinematic, inertial and aerodynamic couplings. In the case of roll channel dynamics, aerodynamic couplings are dominant and apears because of two factors: roll induced moment and roll cross coupling moment.
After study and aerodynamic modeling of mentioned factors, based...
After study and aerodynamic modeling of mentioned factors, based...
Investigating the Permeability and Mechanical Properties of Horizontal Joints in Roller Compacted Concrete Dams
, M.Sc. Thesis Sharif University of Technology ; Ghaemian, Mohsen (Supervisor) ; Toufigh, Vahab (Supervisor)
Abstract
Roller compacted concrete is a dry concrete with zero slump which is constructed in layers. Roller compacted concrete dams are generally weak in interlayers. The bonding strength and permeability of the interlayer affect the performance of the dam’s structure and its safety. In this study, the mechanical characteristics and the permeability of the interface layer of RCC are investigated by considering three key parameters, including water-to-cement ratio (w/c) of concrete, w/c ratio of bedding mortar and time interval between pouring each layer. More than 300 RCC specimens are prepared. To evaluate the properties of the interface between the mortar and the first layer surface, various tests...
Robust Adaptive Controller Design For Attitude of Flexible Launch Vehicle With Navigation System Uncertainty
, M.Sc. Thesis Sharif University of Technology ; Fathi, Mohsen (Supervisor) ; Khoshnod, Abdollmajid (Supervisor)
Abstract
In this thesis first a flrxible launch vehicle is modeled and simulated by taking the moment vibrations into consideration, then navigation system and it’s uncertainties which depicts more realistic performance are added up and the guidance is designed based on pitch-programming. Adaptive robust controller is designed and implemented with the approach of sliding mode such that making the system able to keep it’s despite of navigation uncertainties and flexibilities, also controlling the attitude in the framework of adaptivity and robustness
Determination of the Plastic Zone at the Tip of a Crack in Pressure-Sensitive Materials Using RKPM
, M.Sc. Thesis Sharif University of Technology ; Mohammadi Shoja, Hossein (Supervisor) ; Jahanshahi, Mohsen (Supervisor)
Abstract
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...
Design and Optimization of Looped Thermo-acoustic Engine
,
M.Sc. Thesis
Sharif University of Technology
;
Soltani, Mohammad Reza
(Supervisor)
;
Karimi, Mohsen
($item.subfieldsMap.e)
Abstract
Thermo-acoustic sience is the conversion of heat to power through the sound wave. Thermoacoustic engines for different reasons like easy making, not having moving parts and so high reliablibility of system is in attention for researchers. Also looped-tube thermoacoustic engines are very new in the world and sience and thechnology of them belong to a few companies and for different reasons are replacing different kinds of thermoacoustic engines.They have higher efficiency than other types. They can be made in large scales. They have a larger thermal range. In this research, the numerical study of one, two and four stage looped-tube thermoacoustic engines has investigated with the help of...
Scale-up of Saturation Function in Composite Cores
, M.Sc. Thesis Sharif University of Technology ; Ghazanfari, Mohammad Hossein (Supervisor) ; Masihi, Mohsen (Co-Advisor)
Abstract
Water injection is one of the main methods of enhanced oil recovery that its success depends on exact study of main effective parameters. Saturation functions including relative permeability function and capillary pressure function are one of the effective parameters on the success of water injection projects. In many reservoirs there is wide heterogeneity and various layering that have different absolute permeability. These features result in uncertainty to measurement of curves of saturation function. Experimental studies on this field are carried out on the composite cores that show heterogeneity and layering media of reservoir. By Scaling up the saturation functions from single cores to...
Screening of the EOR Scenarios for Shaly Heavy Oil Reservoirs Using Five-Spot Glass Micromodel: an Experimental Study
, M.Sc. Thesis Sharif University of Technology ; Masihi, Mohsen (Supervisor) ; Ghazanfari, Mohammad Hossein (Supervisor) ; Kharrat, Riyaz (Supervisor)
Abstract
Most of the heavy oil reservoirs contain discontinuous shaly structures which affect fluid flow through porous media as well as oil recovery efficiency during EOR processes. However, selecting the best EOR technique which maximizes the oil recovery remains a topic of debate in the literature. In addition the effect of shale geometrical characteristics including: spacing from wells, discontinuity, orientation, number of shale streaks, shale's spacing and length on oil recovery factor are not well understood. In this work experiments have been performed on one-quarter five-spot glass micromodels. These models have been developed by a new method using laser technology. Generally, this research...
Human serum protein adsorption onto synthesis nano-hydroxyapatite
, Article Protein Journal ; Volume 31, Issue 2 , February , 2012 , Pages 150-157 ; 15723887 (ISSN) ; Massah Bidgoli, M ; Behrashi, M ; Mohsen Nia, A ; Sharif University of Technology
2012
Abstract
Adsorption of human serum proteins (Albumin and total protein) onto high purity synthesis nano-hydroxyapatite (HA), Ca 10(PO 4) 6(OH) 2, has been studied in a wide temperature range by UV-visible spectrophotometer. Adsorption isotherm is basically important to describe how solutes interact with adsorbent, andiscriticalinoptimizing the use of adsorbent. Inthe present study, the experimental results werefitted tothe Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (DR) models to obtain the characteristic parameters of each model and square of the correlation coefficients (R 2). According to the results, the DR isotherm model had the best agreement with the experimental data. The effect of...
Sole versus dual-sourcing under order dependent lead-times and prices [electronic resource]
, Article Computers And Operations Research, Published in: Elsevier Journals ; Volume 36, Issue 12, December 2009, Pages 3272–3280 ; Eshghi, Kourosh ; Sharif University of Technology
Abstract
In this paper, we consider a dual-sourcing model with constant demand and stochastic lead times. Two suppliers may be different in terms of purchasing prices and lead-time parameters. The ordering takes place when the inventory level depletes to a reorder level, and the order is split among two suppliers. Unlike previous works in the order splitting literature, the supply lead time between vendor and buyer as well as unit purchasing prices is considered to be order quantity dependent. The proposed model finds out the optimal reorder point, order quantity and splitting proportion, using a solution procedure. Numerical results show that neglecting the relationship between ordering batch size...
Sol-gel nanostructured titanium dioxide: Controlling the crystal structure, crystallite size, phase transformation, packing and ordering
, Article Microporous and Mesoporous Materials ; Volume 112, Issue 1-3 , 2008 , Pages 392-402 ; 13871811 (ISSN) ; Fray, D. J ; Mohammadi, A ; Sharif University of Technology
2008
Abstract
The anatase phase of titania was stabilised with physically modifying particulate sol-gel process. Two major parameters, peptisation temperature and drying temperature, were identified which were responsible for retarding the anatase to rutile phase transformation, crystal growth and packing of primary particles. The critical nucleus size of transformation was controlled by natural (at 25 °C) and artificial (at 50 and 70 °C) peptisation techniques. Moreover, sintering of primary particles was controlled by cool (at 0 and 5 °C) and normal (at 25 °C) drying techniques. Fourier transform infrared spectroscopy (FT-IR) analysis confirmed that a full conversion of titanium isopropoxide is obtained...
3D distributed modeling of trolling-mode AFM during 2D manipulation of a spherical cell
, Article Journal of Nanoparticle Research ; Volume 23, Issue 4 , 2021 ; 13880764 (ISSN) ; Nejat Pishkenari, H ; Mohammadi Moghaddam, M ; Sharif University of Technology
Springer Science and Business Media B.V
2021
Abstract
In this study, a general 3D distributed modeling of Trolling-Mode AFM (TR-AFM) as a nanorobot is presented to analyze the 2D manipulation process of a spherical cell. To this aim, the analysis is categorized into 3 sections. In the first section, 6 deformations of TR-AFM are taken into account, and the standard model of the system is obtained. Moreover, the system is simulated in ANSYS Workbench. The results of modal and transient analyses of the system from both analytical and software methods reveal high agreement, which confirms the accuracy of the presented analytical model. In the second section, by utilizing the 3D derived model, displacement of a spherical yeast single cell (W303)...
Effect of Initial Static Shear Stress on Liquefaction Resistance of Babolsar Sand Using Cyclic Simple Shear Tests
, M.Sc. Thesis Sharif University of Technology ; Haeri, Mohsen (Supervisor)
Abstract
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...
Three Dimensional Dynamic Analysis of Concrete Faced Rock-Fill Dams to Rayleigh Waves Considering Dam-Foundation Interaction and Spatial Variability of Earthquake Ground Motion
, M.Sc. Thesis Sharif University of Technology ; Haeri, Mohsen (Supervisor)
Abstract
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...
, M.Sc. Thesis Sharif University of Technology ; Haeri, Mohsen (Supervisor)
Abstract
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...
Effective Permeability of Isotropic Overlapping Sandbodies in 2D Using Percolation Theory
, M.Sc. Thesis Sharif University of Technology ; Masihi, Mohsen (Supervisor)
Abstract
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...
Dynamic NMR Study of Ethyle-4-Morpholine-Carbotiate
, M.Sc. Thesis Sharif University of Technology ; Tafazzoli, Mohsen (Supervisor)
Abstract
In this project rotational barrier around the C-N bond in 4-ethyle-morpholine- carboxylate has been studied using DNMR spectroscopy. 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 bandshape simulator programs, DNMR and MEXICO. The rate constants obtained from simulations, were used for calculation of thermodynamic activation parameters (∆G#, ∆H#, ∆S# and Ea). ∆G# 298 value of 13.66 Kcal/mol for 4-ethyle-morpholine- carboxylate...
Thermal Behavior of Concrete Arch Dams Including Water Level Fluctuations
, M.Sc. Thesis Sharif University of Technology ; Ghaemian, Mohsen (Supervisor)
Abstract
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...