Sharif Digital Repository

Microbial enhanced oil recovery (MEOR) is receiving renewed interest worldwide in recent years as a viable method while not damaging the reservoir is proven to be remarkably effective, however to some extent costly. This method is based on microorganisms' activities to reduce residual oil of reservoirs, which is dependent on behavior of inherent microorganisms or injection of bioproduct of external microorganisms. In this work, five bacterial species were taken from MIS crude oil that is one of the aging Persian fractured reservoirs. These microorganisms are substantially strong in increasing oil recovery especially by reducing IFT and other MEOR mechanisms such as change of wettability of... 

This paper investigates the static and dynamic characteristics of composite thin-walled beams that are constructed from a single-cell box. The structural model considered herein incorporates a number of nonclassical effects, such as material anisotropy, transverse shear, warping inhibition, nonuniform torsional model and rotary inertia. The governing equations were derived using extended Hamilton's principle and solved using extended Galerkin's method. The effects of fiber orientation on static deflection and natural frequencies are considered and a number of important conclusions are outlined. © 2007 Elsevier Ltd. All rights reserved  

A smeared crack approach has been proposed to model the static and dynamic behavior of mass concrete in three-dimensional space. The proposed model simulates the tensile fracture on the mass concrete and contains pre-softening behavior, softening initiation, fracture energy conservation and strain rate effects under dynamic loads. It was found that the proposed model gives excellent results and crack profiles comparing with the available data under static loads. Morrow Point dam was analyzed including dam-reservoir interaction effects to consider its nonlinear seismic behavior. It was found that the resulted crack profiles are in good agreement with the contour of maximum principal stresses... 

This paper deals with investigation of fluid flow on static and dynamic behaviors of carbon nanotubes under electrostatic actuation. The effects of various fluid parameters including fluid viscosity, velocity, pressure and mass ratio on the deflection and pull-in behaviors of the cantilever and doubly clamped carbon nanotubes are studied. Furthermore, the effects of temperature variation on the static and dynamic pull-in voltages of the doubly clamped carbon nanotubes are reported. The results reveal that altering the fluid parameters significantly changes the mechanical and pull-in behaviors. Hence, the proposed system can be applied properly as a nano fluidic sensor to sense the various... 

This paper summarizes a research project in the field of design and manufacturing of a water brake dynamometer for power testing facilities. In the current study, the design process of a water brake with drilled rotor disks is presented. This process is examined against the development of a water brake for a 4MW gas turbine power measurement at 15,000 RPM speed. The proposed algorithm is based on vital assumptions such as; applying product designing issues and limited modular analysis that urges the disciplinary attitude and leads to the possibility of rapid development, easy maintenance and ease of access. The final scheme is divided into six disciplines with functional classification.... 

This is an experimental study on the boundary layer over an airfoil under steady and unsteady conditions. It specifically deals with the effect of plunging oscillation on the laminar/turbulent characteristics of the boundary layer. The wind tunnel measurements involved surface-mounted hot-film sensors and boundary-layer rake. The experiments were conducted at Reynolds numbers of 0.42×10 6 to 0.84 × 10 6 and the reduced frequency was varied from 0.01 to 0.11. The results of the quasi-wall-shear stress as well as the boundary layer velocity profiles provided important information about the state of the boundary layer over the suction surface of the airfoil in both static and dynamic cases. For... 

Accurate prediction of static and dynamic response of nano structures is one of the important interests of scientists in the last decade. Nano bearing as an important part of nano machines has been extensively implemented in recognizing and disassembling cancerous cells and building molecular support structures for strengthening bones. For this reason, Molecular Dynamic Method and some experimental methods are implemented in this area. As nano ball bearing is one of the most important components of nano machines, a large number of studies are concentrated to analyze it statically and dynamically. In this paper, a Fullerene is simulated by a spherical super element whose stress, deformation... 

With respect to the influence of nanoparticles on mass transfer characteristics, limited number of studies available in the literature, deal primarily with gas-liquid systems. In this work, mass transfer performance and hydrodynamic characteristics including static and dynamic dispersed phase hold-ups of nanofluids have been investigated for pulsed liquid-liquid extraction column (PLLEC). The nanofluids used were prepared by dispersing SiO2 nanoparticles of 0.01, 0.05 and 0.1 volume percent with two different hydrophobicities in kerosene as base fluid using ultrasonication. UV-vis spectrophotometer was also used for evaluation of the nanofluids stability. The results were compared with... 

Prior to the design and fabrication of MEMS/NEMS devices, analysis of static and dynamic behaviors of these systems is necessary. In the present study, the nonlinear dynamic behavior of micro- and nano-mechanical resonators is investigated and classified based on the resonator’s physical parameters for first time. The Galerkin method is used to convert the distributed-parameter model to a nonlinear ordinary differential equation where mid-plane stretching, axial stress, DC electrostatic and AC harmonic voltages are taken into account. To obtain the analytical frequency response of the micro resonator near its primary resonance, the second order multiple scales method is applied to the... 

In this paper, the development of a neutron noise simulator for hexagonal-structured reactor cores using both the forward and the adjoint methods is reported. The spatial discretisation of both 2-D 2-group static and dynamic equations is based on a developed box-scheme finite difference method for hexagonal mesh boxes. Using the power iteration method for the static calculations, the 2-group neutron flux and its adjoint with the corresponding eigenvalues are obtained by the developed static simulator. The results are then benchmarked against the well-known CITATION computer code. The dynamic calculations are performed in the frequency domain which leads to discarding of the time... 

Desktop and miniaturized machine tools are a new trend in small scale and customized manufacturing. The performance of these machines in terms of their energy consumption, machining fluid consumption and their precision have been investigated in the literature, but the effect of miniaturization on static deflection, stability against chatter and the resulting surface error has not been studied. In this paper, the performance of the desktop milling machine tool in terms of their static and dynamic form errors is studied. The performance of a miniature milling machine used for end milling of a typical workpiece is compared with a similar machine of conventional size through dimensional... 

In this paper, we study the power allocation problem in multi-cell OFDMA networks, where given the tradeoff between user satisfaction and profit of the service provider, maximizing the revenue of the service provider is also taken into account. Consequently, two Stackelberg games are proposed for allocating proper powers to central and cell-edge users. In our algorithm, assuming the fact that users agree to pay more for better QoS level, the service provider imposes optimum prices for unit-power transmitted to users as they request different levels of QoS. In addition, in order to improve system performance at cell-edge locations, users are divided into two groups based on their distance to... 

Prior to the design and fabrication of MEMS/NEMS devices, analysis of static and dynamic behaviors of these systems is necessary. In the present study, the nonlinear dynamic behavior of micro- and nano-mechanical resonators is investigated and classified based on the resonator’s physical parameters for first time. The Galerkin method is used to convert the distributed-parameter model to a nonlinear ordinary differential equation where mid-plane stretching, axial stress, DC electrostatic and AC harmonic voltages are taken into account. To obtain the analytical frequency response of the micro resonator near its primary resonance, the second order multiple scales method is applied to the... 

An advanced optimization system for Vehicle Routing and Scheduling Problems (VRSP), which is one of the Supply Chain Planning modules, is introduced. An object oriented system, Computer Aided Routing and Scheduling (CARS) can handle complicated distribution models using advanced heuristic optimization algorithms. To classify various types of routing and scheduling problems in a structured manner, a classification scheme is introduced based on the main objects of VRSP. Also, the modeling and solution approach in the CARS optimization engine has been elaborated. Main static and dynamic objects of the system as well as their relationships and interactions have been explained. The user interface... 

In this paper, we propose a new 4-legged 6-DOF redundantly actuated UPS parallel mechanism. Kinematics, singularity and dynamics analyses of the proposed mechanism are addressed. Inverse kinematics has a closed-form solution, whereas the forward kinematics has a semi-closed form solution. Also, the Jacobian matrix has been determined using the concept of reciprocal screws. Using the principle of virtual work and minimum norm method, a general formulation for the inverse dynamics of redundantly actuated parallel manipulator is presented. Moreover, the proposed redundant mechanism has been compared with a similar but nonredundant mechanism in three aspects: reachable points, and actuation... 

Smart water injection is determined as an effective EOR process to change the wettability and interfacial tension for better micro/macro sweep efficiencies. This water contains reactive ions such as Mg ∧(2+), Ca ∧(2+) and SO-4 ∧(2-) which can act as potential determining ions and change the surface charge of calcite rocks. One of the major concerns in the execution of an effective waterflood, especially in tight carbonate reservoirs, is the incompatibility between the formation brine and the injecting water. This research work aims to investigate the most important challenge of waterflooding process related to the possible formation damage because of inorganic scale deposition during...